SlideShare a Scribd company logo
1 of 113
Download to read offline
Limnology and Wetland Management
NaRM3017
By: Tesfahun Tesema
August,2023
18-Apr-24 1
1. Introduction
1.1. Definitions and Concepts of Limnology
• Limnology – is the study of inland water; it includes some
waters more saline than the ocean, ponds, streams,
rivers, to lakes and reservoirs – large and small.
• It encompasses everything from the geologic origins of
lakes to the development of a lake in prehistoric times
(Paleolimnology) to the structure of food webs.
• As do oceanographers, limnologists generally specialize in
physical, chemical or biological limnology.
18-Apr-24 2
1.1. Definitions and Concepts of Limnology Cont,,,
• The history of limnology has steadily evolved over the
last 120 years, both conceptually and technically.
• Beginning with Forel’s classic work on Lac Léman,
published in three vol. (1892, 1895 and 1904), and
Forbes’ classic work on lakes as microcosms (1887),
scientific interest in limnology – which encompasses the
physics, chemistry and biology of lakes and other inland
water bodies – has continued to grow.
18-Apr-24
3
1.1. Definitions and Concepts of Limnology Cont,,,
• Initially regarded as the science of lakes, limnology now
encompasses freshwater and saline lakes in the inland of
continents, and all physical, chemical and biological
interactions in these ecosystems.
• Chemical processes and mechanisms occurring in inland
waters are highly dependent on the geochemistry of soils
in drainage basins.
18-Apr-24
4
1.1. Definitions and Concepts of Limnology Cont,,,
• Aquatic systems interact with their drainage basin in
various sub-systems and components.
• That concept and comprehensive studies on drainage
basins in relation to lakes, rivers, reservoirs and wetlands
are more recent
• Baldi (1949), defined limnology as the scientific study of
the interrelated processes and methods by which matter
and energy are transformed in a lake.
18-Apr-24
5
1.2. Importance of limnology as a science
The most important progress in limnology as a science
over the last ten years has been the growing
understanding of the dynamic ecology of aquatic systems
and applications in solving problems of protection,
conservation and restoration of lakes.
Another important dev’t in it has been the ability to
predict the trends and characteristics of lakes and
reservoirs over time, especially in terms of controlling
influences such as eutrophication and fish stock.
18-Apr-24
6
1.3. Contributions of limnology to theoretical
ecology
Throughout its history as a science, limnology has contributed
significantly to the development of theoretical ecology.
Contributions include:
Community succession and factors that control it (studies
of phytoplankton succession, development of the benthic
community in different types on substrata, periphyton
succession, and succession of fish communities);
Evolution of communities (studies on eutrophication in
lakes, restoration of eutrophic lakes and reservoirs);
18-Apr-24
7
1.3. Contributions of limnology to theoretical
ecology
Community diversity and spatial heterogeneity (studies of
periphyton and phytoplankton in different ecosystems,
aquatic insects, comparative studies on lakes, reservoirs
and floodplains. Theory and studies of ecotones);
Primary production and energy flow (studies on the primary
productivity of phytoplankton, aquatic macrophytes and
periphyton, feeding habits of zooplankton and fishes.
Physiological responses of phytoplankton to light intensity
and concentration of nutrients);
18-Apr-24
8
1.3. Contributions of limnology to theoretical
ecology
Distribution of organisms and factors that control dispersal
and colonization mechanisms (studies on the vertical
migration of zooplankton, vertical distribution of
phytoplankton, colonization in reservoirs and temporary
waters, distribution of aquatic organisms in lakes, rivers and
reservoirs);
Evolution of ecosystems (studies on eutrophication,
reservoirs, monitoring reservoirs and alterations resulting
from human activities).
18-Apr-24
9
1.4. Branches of Limnology
18-Apr-24 10
1.4. Branches of Limnology
Limnology is the study of the structural and functional
interrelationships of organisms of inland waters as they are
affected by their dynamic physical, chemical, and biotic
environments.
Physical limnology
deals with the physical properties of the water in lakes and
rivers. This includes changes in light levels, water
temperatures, and water currents.
Geology of basin (origin, morphology, leaching minerals)
18-Apr-24
11
1.4. Branches of Limnology
Biological Limnology
It is designed to provide an in depth understanding of the
principles and paradigms of aquatic ecosystems and their
watersheds.
Base is photosynthesis - primary productivity
Regulated by, and may regulate, physical and chemical
factors
18-Apr-24
12
1.4. Branches of Limnology
Chemical limnology
It focuses on the cycling of various chemical substances in
lakes and rivers.
Several factors affect the chemistry of lakes and rivers
including the chemical composition of the soil in the
watershed, the atmosphere (mass of air surrounding Earth)
and the composition of the riverbed or lake bottom.
18-Apr-24
13
1.4.1. Physical Limnology
Properties of Water
Water is an extremely unusual substance.
It exists in three states: solid, liquid and gas.
The transition from one phase to another depends on a
rearrangement of the molecules and the configuration of
its aggregates.
18-Apr-24
14
1.4.1. Physical Limnology Cont…
Properties of Water
The physical properties of water, especially its temperature-
related anomalies in density, play a key role in the
circulation and stratification processes in lakes and
reservoirs, and in the vertical organization of the system in
temperate lakes in winter, when surfaces freeze.
Those properties of water, particularly its anomalies in
density, surface tension and thermal features, are
important to aquatic organisms inhabiting the liquid
medium. 18-Apr-24
15
1.4.1. Physical Limnology Cont…
Properties of Water
The essential life processes of all organisms depend on
water.
Water is the universal solvent carrying the dissolved gases,
elements, substances, and organic compounds that form
the basis of all plant and animal life on the planet.
Hydrogen in water functions as a source of electrons in
photosynthesis. Water’s unique properties are related to its
atomic structure, intermolecular hydrogen bonds and the
molecular associations in the solid, liquid and gas phases.
18-Apr-24
16
1.4.1. Physical Limnology Cont…
Properties of Water
Oxygen is highly electronegative; in water, the oxygen
atom binds with two hydrogen atoms that retain a +ve
charge.
Because water is a strong dipole with two hydrogen atoms
(positive) and one oxygen atom (negative), in addition to
the distance (as charge x distance), there are significant
effects on water’s physical properties.
Without this strong dipolar feature, water would not be
liquid.
18-Apr-24
17
1.4.1. Physical Limnology Cont…
Importance of water’s physical and chemical properties for
aquatic organisms
oThe entire life cycle and behaviour of aquatic organisms are
influenced by the physical and chemical properties of
water, especially its density, anomalies of density, thermal
properties and capacity as a universal solvent.
oThe surface tension of water, which also has great
biological significance, varies with temperature and the
concentration of dissolved solids.
18-Apr-24
18
1.4.1. Physical Limnology Cont…
Importance of water’s physical and chemical properties for
aquatic organisms
oWater’s surface tension enables a set of organisms – neuston
or pleuston – to utilize the interface between the water and
the atmosphere for support as well as for movement.
oAnother biologically important property of water is its
dynamic viscosity, which is the force required to move 1 kg a
distance of 1 meter in 1 second through a mass of water.
oIt depends on the temp. of the water and its salt content.
18-Apr-24
19
1.4.1. Physical Limnology Cont…
No Property Comparison with
other substances
Importance to aquatic
systems
1 Density Under standard pressure
maximum density is at
3.94 0C, not 0 0C; expands
upon freezing
Allows lake stratification, and
surface freezing rather than
bottom freezing
2 Melting
and boiling
points
Both properties unusual;
very high
Allows water to exist as a liquid
3 Viscosity Moderate Influences the case of water
mixing, provides resistance to the
movement of organisms, and
helps determine the
sedimentation rate of particles
4 Specific
Heat
capacity
Highest of any liquid,
other than ammonia
Moderates ( Buffers) temperature
extremes 18-Apr-24
20
1.4.1. Physical Limnology Cont…
No Property Comparison with
other substances
Importance to aquatic systems
5 Heat of
Vaporizati
on
One of the highest
known
Important to heat transfer in inland water and
atmosphere
6 Surface
tension
Very high Increases the difficulty of surface waves breaking
and thereby slowing the rate of heating and
cooling in lakes, allows certain insects to walk on
water surfaces
7 Absorptio
n of
radiation
Large in infrared
region, but moderate
in the photosynthetic
/ visible region
Allows greater heat absorption in the surface
water, but reduced surface absorption at shorter
wavelengths, allowing a greater penetration of
photosynthetically available radiation
8 Solvent
Propertie
s
Dipolar nature makes
it excellent solvent
for salts and other
polar molecules
Important in dissolution and transport of
dissolved substances from catchments and
atmosphere to aquatic systems
18-Apr-24
21
1.4.1. Physical Limnology Cont…
I. Water and Heat
Most important physical property of water is it’s Heat Capacity.
Specific heat is the amount of heat needed to raise or lower
the temperature of 1g of substance by 1 degree Celsius
It’s unusual thermal characteristics –
Prevent wide temperature variations from day to night and
from summer to winter
Permit vast amounts of heat to flow from equatorial to polar
areas and Power earth’s great storms, winds
18-Apr-24
22
1.4.1. Physical Limnology Cont…
• The specific heat of water is higher than nearly all other
liquids.
• It takes 4.187 J (one calorie ) to heat 1 g (1cm 3) of pure
water by 1 °C (at 15 °C ).
• The high specific heat of water, as well as a high latent
heat of evaporation, is a function of the relatively large
amounts of heat energy required to disrupt the hydrogen
bonding of liquid water molecules.
18-Apr-24
23
1.4.1. Physical Limnology Cont…
• These heat-requiring and heat-retaining properties of water
provide a much more stable environment than is found in
terrestrial situations.
• Fluctuations in water temperature occur very gradually.
• Daily and seasonal extremes in temperature are small in
comparison to those of aerial habitats.
• The high specific heat of water can also have profound
effects on climatic conditions of adjacent air and land
masses.
18-Apr-24
24
1.4.1. Physical Limnology Cont…
• The specific heat (thermal capacity) of ice below 0°C is
about half (0.5/g/°C) that of water and decreases
progressively at temperatures below 0°C.
• The amount of heat required, however, to change ice to
liquid water is large (latent heat of melting =79.72 cal/g) and
is very much larger for disruption of hydrogen bonding in
evaporation of water (latent heat of evaporation — 540
cal/g) or for direct sublimation of ice to water vapor (latent
heat of sublimation = 679 cal/g).
18-Apr-24
25
1.4.1. Physical Limnology Cont…
• Conversely but similarly, a large amount of heat must be lost
for the fusion of molecules of 0°C water to ice (latent heat of
fusion = 79.72 cal/g).
• Because of these properties, large energy inputs are required
to melt ice in the spring, and large energy losses are required
in order to form ice cover in the winter.
18-Apr-24
26
1.4.1. Physical Limnology Cont…
Inland Water Bodies
• The inland waters which include both fresh water masses and
estuarine waters of varying salt content are clearly
distinguishable from the salt waters of the oceans.
• The inland water masses are discrete and being isolated
within the specific land area, acquire the characteristic
chemical composition of the land, by exchange between soil
and water.
18-Apr-24
27
1.4.1. Physical Limnology Cont…
• The oceanic water on the other hand is open and mixing
together by wind action and currents and therefore more
homogeneous in chemical composition.
• However, the land water exchange is limited to coastal areas.
• The estuarine waters are mixtures of sea and freshwater, but
with the higher content of salts in the sea water (150 – 200
times that of freshwater), are dominated by the sea water
effects.
18-Apr-24
28
1.4.1. Physical Limnology Cont…
• According to Hutchinson (1959), limnology is the large
variety, individual and groups of inland water bodies, the
diversity being caused by the diversity of their origin as well as
by the diversity of their chemistry and biology.
Types of inland water
• Frey (1960) has classified inland waters in three different ways
viz, depending on whether the water is stationary or flowing,
depending on whether the water mass is natural or artificial
and permanent / temporary.
18-Apr-24
29
1.4.1. Physical Limnology Cont…
a. Flowing waters (Lotic waters)
• These include creeks, streams and rivers mentioned in that
sequence because of their sequence of succession also in the
same order, through the natural processes of lengthening
and widening of running waters.
• In these, there is continuous current of water in one direction.
• The organisms inhabiting these waters have complexity of
adaptation towards the increase in water current speed.
18-Apr-24
30
1.4.1. Physical Limnology Cont…
b. Standing waters (Lentic waters)
• Here, water current is not a major ecological factor; unlike in
the lotic series lakes, ponds and swamps form the lentic
series.
• It includes all forms of inland waters – lakes, ponds, swamps
and their various intergrades in which the water does not flow
continuously in definite directions.
• Essentially, the water remains standing, though a certain
amount of water mov’t may occur, such as wave action,
internal currents or flow of water in the vicinity of inlets and
18-Apr-24
31
1.4.1. Physical Limnology Cont…
Inland waters and the water cycle
• Most of inland water bodies are freshwater and they account
only for a small fraction (~0,0.2%) of the whole hydrosphere.
• Some more freshwater (~1%) is groundwater and the ~2% of
the hydrosphere is confined as ice in polar caps and in
glaciers.
• Most of the water on Earth (~97%) is made up by seawater.
• In spite of the uncertainty of these estimates, without doubt
the usable freshwater allowing for the existence of life on the
continents is a very small fraction of the hydrosphere.
18-Apr-24
32
1.4.1. Physical Limnology Cont…
Inland waters and the water cycle
• The mechanism supplying new freshwater to continents as
the water flows away from them is the water cycle
• The sun provides the energy that keeps the water cycle
moving through the evaporation of oceanic and inland
surface waters and the evapotranspiration of terrestrial
vegetables.
• Water vapor then progressively condensate in the
atmosphere, eventually returning to the ground as rain or
snow.
18-Apr-24
33
1.4.1. Physical Limnology Cont…
18-Apr-24
34
1.4.1. Physical Limnology Cont…
Lakes
• Lakes are depressions surrounded by land and hold standing
fresh or saline water all year round.
• Lakes are also described as water bodies that are larger than
ponds, have wave action on the shoreline, or where wind-
induced turbulence plays a major role in mixing the water
column.
• Lakes are bodies of water enclosed by land.
• Lakes are created by natural or human–initiated processes.
18-Apr-24
35
1.4.1. Physical Limnology Cont…
Origin of Lakes
• Lakes’ origins and morphometry play an important role in
their physical, chemical and biological processes, since,
along with regional climatic processes, these factors
contribute to the functioning of the lakes.
• The study of geomorphology contributes significantly to
understanding the origin of lakes and the dynamics of the
formative processes of lake ecosystems.
• Morphology, the study of lake shapes, is related to the
origins of each system. 18-Apr-24
36
1.4.1. Physical Limnology Cont…
• Morphometry deals with the quantification of these forms
and elements.
• Lake morphology and morphometry basically depend on the
processes from which lakes originated.
• All inland water systems originated from a variety of natural
processes and diverse formative mechanisms that vary from
region to region and from one geologic era to another.
• Because most lakes in an area have the same origin, we
refer to “lake districts”
18-Apr-24
37
1.4.1. Physical Limnology Cont…
Formation of Lakes:- Tectonic/Rift-Valley
• The lake is formed by movements of the Earth’s crust, such
as faults that result in depressions. They are often formed in
rift valleys (graben).
• Well-known examples are Lake Baikal (Siberia), Lake
Tanganyika (Africa) and Lake Victoria (Africa), which was
facilitated by the obstruction of the Kagera and Katonga
Rivers, creating a 68,422-sq.km basin.
• List Rift-Valley Lakes of Ethiopia.
18-Apr-24
38
1.4.1. Physical Limnology Cont…
• Tectonic movements can occur through the emergence or
subsiding (lifting or sinking) of areas with shifts in sea level.
• The formation of lakes then begins with isolation from the
ocean.
Volcanic Lakes
• The formation of depressions, or hollows that do not drain
naturally, produces a series of volcanic lakes.
• Volcanoes are common in areas where tectonic mov’ts
occur.
• Identify lakes of Ethiopia, that are volcanic in origin.
18-Apr-24
39
1.4.1. Physical Limnology Cont…
• Lava discharged by active volcanoes can obstruct a river and
form lakes.
• Examples include some usually small lakes in Africa, Asia,
Japan and New Zealand.
Glaciation
• Many present-day lakes were formed by glacial action.
• These movements, which can be catastrophic, cause
deposits or corrosion of masses of ice and their depositions,
with subsequent thawing.
18-Apr-24
40
1.4.1. Physical Limnology Cont…
Solution lakes
• Many lakes are formed when deposits of soluble rock are
gradually dissolved by percolating water.
• For example, solution lakes are formed by the dissolution of
CaCO3 from slightly acidic water containing CO2.
Lakes formed by fluvial activity
• Rivers, as they flow, have an obstructive capacity (due to
deposition of sediments) and an erosive capacity (due to
transport of sediment).
18-Apr-24
41
1.4.1. Physical Limnology Cont…
• Many lateral lakes are formed by the activity of rivers
depositing sediments that obstruct tributaries.
Lakes formed by wind action
• Depressions formed by wind action, or blocked by
accumulation of dunes, can also lead to the formation of
lakes.
• Such lakes are ephemeral, since hollows thus formed retain
water only during rainy periods, and become increasingly
saline due to evaporation in the dry season, and, finally, they
dry up. 18-Apr-24
42
1.4.1. Physical Limnology Cont…
Lakes formed by organic deposits
• The growth of plants and associated detritus can cause
obstructions in small rivers and depressions.
Landslides
• Large-scale movements of rock or soil, resulting from
abnormal weather events such as excessive rainfall or the
action of earthquakes, can produce lakes by blocking
valleys. Such lakes are usually temporary, due to rapid
erosion that occurs in the unconsolidated dam.
18-Apr-24
43
1.4.1. Physical Limnology Cont…
Coastal lagoons
• Deposition of material on the coast, produced in regions
where there are bays or inlets, can lead to the creation of
coastal lakes.
Lakes of meteoric origin
• On rare occasions a meteorite striking the Earth’s surface
can lead to a depression that later accumulates water,
forming a lake.
18-Apr-24
44
1.4.1. Physical Limnology Cont…
Multi-origin lakes
• Several of the processes described – such as glaciation,
heavy precipitation, and tectonic movement – can interact
and lead to the formation of a lake or a complex of lakes.
• To understand the origins and formation of lakes, it is first
necessary to determine their bathymetry and varying
depths.
18-Apr-24
45
1.4.1. Physical Limnology Cont…
Lake Classification According to their Richness
• Oligotrophic lakes are nutrient-poor lakes of glacial origins
with underlying rocks made up mainly of granite.
• Mesotrophic lakes have balanced nutrient status but their
depths usually allow thermal stratification most times of the
year causing differences in abundance of nutrients,
phytoplankton and zooplankton e.g. Rift valley Lakes.
• Eutrophic lakes are nutrient-enriched e.g. depression lakes.
They usually have intensive agricultural activities around
them.
18-Apr-24
46
1.4.1. Physical Limnology Cont…
Classification of Lakes According to Mixing or Stratification
Features
• According to their mixing features lakes can be classified as:
• Holomictic lakes are those completely mix because they
reach uniform temperature and density from top to bottom.
• Full circulation or mixing can occur once or twice a year.
• Monomictic lakes mix from top to the bottom during one
mixing period each year. There are two types of monomictic
lakes namely cold and warm.
18-Apr-24
47
1.4.1. Physical Limnology Cont…
• Dimictic lakes mix from top to bottom during two mixing
periods in the year-spring and autumn.
• Polymictic lakes are also holomictic lakes that mix several
times a year.
• They are too shallow to develop thermal stratification and
their waters mix from top to bottom throughout the year.
• Oligomictic lakes have irregular mixing, which may not occur
every year.
18-Apr-24
48
1.4.1. Physical Limnology Cont…
• Amictic lakes are lakes that never circulate or mix. Amictic
lakes are usually ice covered throughout the year.
• Water temperature in the lake increase with depth (inverse
cold water stratification).?????????????????
• Meromictic lakes are those in which bottom water never
mixes with surface water.
• In these lakes, dissolved substances accumulate at the
bottom, increasing the water density above the value
attributable to temperature alone.
18-Apr-24
49
1.4.1. Physical Limnology Cont…
Zonation in Lakes
• According to light and temperature distribution in a lake,
there are zones with different characteristics in lakes. These
are commonly used in limnological context.
18-Apr-24
50
1.4.1. Physical Limnology Cont…
18-Apr-24
51
1.4.1. Physical Limnology Cont…
The zones of a Lake are:
• Littoral Zone: Is the portion of the lake horizontally
extending from the shore to the point impending the
bottom area where submerged macrophytes and benthic
algae can live.
• This is the part of the lake bottom reached by solar
radiation, included in the photic zone.
• Pelagic Zone: Is the portion of the lake above the depths
not reached by solar radiation.
18-Apr-24
52
1.4.1. Physical Limnology Cont…
• Photic or Euphotic Zone: Is the layer of water vertically
extending from the surface to the depth reached by 1% of
surface solar radiation.
• Aphotic Zone: Is the part of the water column not reached
by solar radiation.
• Epilimnion/Hypolimnion: water layers overlying or underlying
the thermocline.
• Thermocline or Metalimnion: Is the layer of water where the
temperature changes of 1°C per meter.
18-Apr-24
53
1.4.1. Physical Limnology Cont…
• Benthic Zone: is the portion of the lake located at the water
sediment interface.
• In the aphotic zone it is often called profound benthic zone.
18-Apr-24
54
Morphology of Lake Basins
• The shape and size of a lake basin affect nearly all
physical, chemical, and biological parameters of lakes.
• The forms of lake basins are extremely varied and reflect
their modes of origin, how water movements have
subsequently modified the basin, and the extent of
loading of materials from the surrounding drainage basin.
• The morphometry of a lake is best described by a
bathymetric map, which is required for the
determination of all major morphometric parameters.
Morphology and Morphometry of Lakes
• Such a map is prepared by a survey of the shoreline by
standard surveying methods, often in combination with
aerial photography.
• From the map of the shore line a detailed bathymetric map
of depth contours must be constructed from a series of
accurate depth soundings along intersecting transects
(Wetzel, 2001) Morphometric parameters.
• Area (km2) A
• Volume V
• Maximum length Lmax
• Maximum width Lamax
Surface area: grid method
You’ll need:
• Bathymetric map
• Grid paper
Method:
• Count up the number of squares
that fall within the shoreline of
the lake
• Use the map scale to determine
area represented by each square
scale
Area = # squares counted
X area of one square
Atop
Abottom
z
z
z
Calculating Lake Volume
Atop = the area at the top
of the layer
Abottom = the area at the
bottom of the layer
z = the distance between
contour lines
V = the volume of one
layer
 
3
bottom
top A
A
A
A
z
V
bottom
top 



Chapter One Cont…
Maximum length (Lmax) and maximum width
(Lamax)
• The maximum length of a lake is determined based on
maps or aerial photographs or satellite images.
• It is the distance between the two furthest points of the
lake in a straight line.
• The maximum effective length has an important
hydrographic and limnological application, because it
corresponds to the maximum distance between two
uninterrupted points on the lake or reservoir.
Average depth (Z)
• The average depth is determined by dividing the lake’s
volume (V) by its area (A).
• It is an important parameter because the lake’s biological
productivity is generally related to its average depth.
Relative Depth (Zr)
• It is given as a percentage and is defined by the ratio of the
lake’s maximum depth (Zmax) and average diameter.
• The greater the depth, the more probable it is that the lake
presents more stable thermal stratification.
Perimeter (m)
• The perimeter corresponds to measurements of the lake’s
contour, and can be obtained using maps or aerial photographs
and measuring, by various techniques, the values of the
perimeter in meters.
Shoreline development index (DL)
• The shoreline development index is a measure of the degree of
irregularity of the shoreline.
• It is the r/nship b/n the length of the shoreline and the length
of a circumference of a circle with an area equal to that of the
lake.
Chapter One Cont…
• It measures the degree of deviation of the lake or reservoir
from a circular pattern.
• The shoreline development index (DL) is given by:
Chapter One Cont…
Volume development index (Dv)
• This indicator is used to express the type of lake basin
and is defined as the ratio of the lake’s volume to the
volume of a cone with a base area equal to the lake’s area
and a height equal to the lake’s maximum depth.
• The Dv is generally about three times the ratio Z:Zmax.
Average slope (α)
• The average slope (α) is determined by the formula:
• Identifying a lake’s bathymetric profile is also an important factor
because of the relationship between irregularities and depressions and
circulation.
• These depressions can alter thermal and chemical conditions during the
period of stratification.
Chapter One Cont…
• Knowledge of the shape of the lake is essential, because there
is a relationship between the shape and circulation of waters
and mechanisms in the functioning of lakes.
• Significant morphological modifications can occur when a
lake is subject to many impacts, especially from human
activities.
• E.g, deforestation in water basins can significantly alter a
lake’s morphometry and morphology, due to suspended
sediment.
Morphology And Flow In River Ecosystems
• The continual downgradient movement of water,
dissolved substances, and suspended particles in streams
and rivers is derived primarily from the land area
draining into a given stream channel.
• The hydrological, chemical, and biological characteristics
of a stream or river reflect the climate, geology, and
vegetational cover of the drainage basin
River morphology
• Meteoric water flowing down slopes ends up merging to
form small streams which then channel into a river.
• Because of the kinetic energy of the moving water, the river
develops various landforms through channel processes.
• The area supplying water into a river is the drainage basin
(db).
• The boundary b/n drainage basins is a water divide (wd).
• A river system is composed of the main stream (ms) and
many tributaries (t).
• The main fluvial processes are erosion, transportation and
sedimentation.
• In the upper area of a drainage basin, where current velocity
is higher, erosion predominates and valleys composed of
channels and slopes are formed.
• The materials swept downstream are the sediment load,
produced mainly by weathering of the rocks composing
slopes.
• Sediment load is deposited to form an alluvial plain.
• The channel patterns forming in alluvial plains can be
braided, meandering and straight.
• The channel patterns and
forms bring about the
river morphology,
decided by many inter-
related factors such as
discharge, water velocity,
slope, depth and width of
the channel, and riverbed
geology.
Energy penetration in lakes
• the spectrum of the solar radiation reaching lakes surface
and the effect of different wavelengths on organic matter
and living organisms.
• The radiation of higher energies changes the atomic or
molecular structure of matter.
• With decreasing energy content, i.e. in the range of visible
light, the radiation energy is used for photosynthesis, the
biochemical reactions leading to organic matter production
by autotrophic organisms.
• Thus the radiation
in the visible range
400-700 nm is called
Photosynthetically
Active Radiation
(PAR).
• The long wavelength
radiation interacts with
water molecules,
transferring them its
energy and determining
the water heating.
Figure 13. Spectrum and activity of solar radiation reaching the biosphere.
• The amount of solar radiation reaching the surface of lakes varies
depending on the transparency of the atmosphere, latitude and
altitude of the lake.
• When it reaches the lake surface, the radiation is partly reflected,
returning to the atmosphere, and partly refracted, penetrating in
the water.
• The percentage of incident radiation reflected depends on the sun
position according to day time and season, i.e. the incidence
angle.
• The percentage of radiation reflected is minimum when the sun is
at zenith and maximum when the sun is near the horizon
Lake water transparency
• Particles and solutes present in a lake determine its
transparency, which is assessed with the Secchi disk, a
simple instrument firstly used in 1865 by abbot A. Secchi.
• It is a white disk, usually metallic, 20-30 cm in diameter,
tied to a rope.
• The Secchi disk is lowered in water and the depths of its
disappearance and reappearance are measured (Figure 15).
• The average between the two measures is the transparency
of a lake, defined as Secchi disk disappearance depth.
Figure 15. Secchi disk in a transparent (left) and in a turbid lake (right).
The arrows indicate the water level.
Thermal energy and lakes circulation
• The hydrodynamic of a lake is complex because of the
complex interactions between water and the forces moving
it.
• Considering the heat content, affecting the density of lake
waters and therefore their buoyancy, it is transferred:
• - by radiation, when the energy transfer occurs via
electromagnetic waves, without matter transfer
• - by conduction, when heat is transferred through thermal
energy exchange from one molecule to the next one, without
mass movement.
• This is possible when there is a temperature gradient between
water masses
• - by convection, when the heat transfer takes place through
displacement of warm water from one site to another of the
water body.
• This is the prevailing course of heat transfer in fluids.
• Solar radiation warms up the upper water layers and the heat
transfer in deep layers mainly depends on convection and on the
wind.
• The heat transfer in the lake determines its temperature at any
season as a result of the lake heat balance, i.e. the difference
between the input and loss of heat.
• In the temperate zone, a hypothetical lake 20 meters
deep will progressively lose heat during winter, reaching
by the end of the season a temperature close to 4° C at
any depth.
• The wind activity can easily mix surface and bottom
waters that have now the same density.
• The spring circulation thus established transfers the
surface water, in contact with the atmosphere and thus
well oxygenated, towards the lake bottom, charging of
oxygen the whole water column
Figure. Temperature profile and section of a lake during the circulation, in
spring and autumn, and stratification, in summer and winter.
Light In Lakes
• Perhaps the most fundamental set of properties of lakes
relates to the interactions of light, temperature and
wind mixing.
• The absorption and attenuation of light by the water
column are major factors controlling temperature and
potential photosynthesis.
• Photosynthesis provides the food that supports much of
the food web. It also provides much of the dissolved
oxygen in the water.
• Solar radiation is the major source of heat to the water
column and is a major factor determining wind patterns
in the lake basin and water movements.
• Light intensity at the lake surface varies seasonally and
with cloud cover and decreases with depth down the
water column.
• The deeper into the water column that light can
penetrate, the deeper photosynthesis can occur.
• Photosynthetic organisms include phytoplankton, algae
attached to surfaces (periphyton), and macrophytes.
• The rate at which light decreases with depth depends
upon the amount of light-absorbing dissolved substances
(mostly organic carbon compounds washed in from
decomposing vegetation in the watershed) and the
amount of absorption and scattering caused by suspended
materials (soil particles from the watershed, algae and
detritus).
• The percentage of the surface light absorbed or scattered
in a 1 meter long vertical column of water, is called the
vertical extinction coefficient.
TEMPERATURE
• Temperature is defined as the degree of hotness or coldness. It
affects other parameters:
It affect states of water (solid, liquid and gas).
Water has large capacity to hold heat, specific heat capacity of
water equal to unity (i.e. one). Water temp increase, density
decreases until 4oC, any further increase in temperature make
density remain constant.
it also affect dissolved gas, at high temperature low gas
dissolved amount of soluble salt in water increases as temp
increases. Affect biology of aquatic organisms.
TURBIDITY
• Turbidity can be defined as the amount of suspended solids
in water.
• In turbid water, the soil absorbs/ reflects light rays
reducing the amount available for primary production.
• At optimum light intensity, higher photosynthesis thus
dissolved oxygen released into the atmosphere and carbon
dioxide is removed.
• At higher light penetration more nutrients NO3-, PO4-, etc
are utilized thus pH becomes greater as all the acidic CO2
are used up.
AMOUNT OF SUSPENDED SOLIDS IN WATER (TSS)
• When light penetrated water, any suspended solid
absorb/reflect light rays reducing amount of light going
beyond them.
• Thus, the more dissolved solid, the more turbid water
and the less light penetrate it.
• To use this we filter to remove all suspended solids
(both living and non living, organic and inorganic) using
a very fine filter paper with micropore or milipore
(40nm) called micropore membrane filter paper.
WATER COLOUR
• True water colour caused by amount of substance in
solution/ colloidal suspension in it and colour result from
unabsorbed light ray.
• Remember from the incident light.
WATER DEPTH
• Depth shows relative distance between the beds of water
to the overlain shallow water.
• It is related to light penetration, thermal stratification,
volume and photosynthesis and distribution of organism in
the water body.
• It is difficult to define "shallow" or "deeper“ of a water
body because in some purpose 100m is shallow while 30m is
deep in some other areas. The actual variables are:
• 1) The extent to which benthos is illuminated by light.
• 2) The degree at which benthos is separated from the
surface water.
• In shallow water, wind and current induce mixing and
efficiency of energy transfer and nutrient cycling is
therefore enhanced in shallow water, benthos can feed
directly on planktons.
• Critical depth is the point in water which photosynthesis is
the same as respiration.
• The shallower the water, the greater the diurnal swing in
temperature and because a large proportion of the whole
water is within the reach of light radiation.
1.5. Biological
Limnology
BIOTIC ELEMENTS OF AQUATIC
ECOSYSTEMS
• In summary, life forms belong to both plant and
Animal kingdoms. Can be schemed as:
1. PLANTS
• Phytoplankton
• Bryophytes
• Bryophytes
2. ANIMALS
• Zooplankton
• Coelterates e.g. Hydra
• Annelida (but no polychaetes, Nereis occur)
• Arachnid
• Mollusks and Insect
The small front legs help
to gather food and bring it
to the mouth.
The front legs are short
and hard to see if you are
looking down on this
insect, unlike the front
legs of our next guest!
WATER BOATMAN
These insects scavenge
dead plant and animal
material found and along
the bottom of the wetland.
BACKSWIMMER
These predators lie on their
backs just under the water
surface and use their long
front legs to grab insects
that land on the water.
The front legs of the
backswimmer are much
more visible than those of
the water boatman,
allowing easier
identification when both are
viewed from the top.
PREDACEOUS DIVING BEETLE
Diving beetles are predatory
insects that breathe using
tubes that come out of their
rear-ends! Air is obtained
from the surface and stored in
a space underneath their hard
wing-covers created by
thousands of very tiny hairs.
Adult
Larva
Just like butterflies, these
beetles have complete
metamorphosis. Eggs are laid
close to the surface on plants
and larvae that are ferocious
predators hatch and eat things
like mosquito larvae under the
water.
DRAGONFLY NYMPH
Dragonflies have incomplete
metamorphosis. Young dragonflies
live in the water and are called
nymphs. They will shed their skins
many times until they finally come
out of the water to become adults.
Dragonflies are great predators,
and have a mouthpart called a
labium that extends out and grabs
their prey with sharp hooks.
The type of dragonflies we find in the
water here belong to the skimmer or
libellulidae family. They look like
this and can be found crawling along
the muddy bottom of wetlands all
over Ontario.
This is good because both dragonfly
nymphs and adults hunt insects like
mosquitoes!
DRAGONFLY ADULTS
The adult dragonflies we see most
often here are the Common
Whitetail and the Twelve-spot
Skimmer. Both of the pictures
represent male dragonflies. The
females of both of these
dragonflies have duller colouration.
Common Whitetail
Twelve-spot Skimmer
MAYFLY NYMPH
If mayfly nymphs are
present in the aquatic
ecosystem it indicates that
the health of the ecosystem
is good.
Mayfly nymphs require
clean water that is well
oxygenated, and excess
nutrient levels cannot be
tolerated.
Mayflies will soon disappear
from ecosystems that are
negatively affected by
human activity. Scientists
find these types of
organisms to be good
indicator species of
Nymph
Adult
AMPHIBIAN GROWTH AND
ECOSYSTEM HEALTH
Tadpoles develop
from eggs laid in the Spring.
Most of the dots you see in this egg cluster
will become tadpoles in a healthy
ecosystem.
Tadpoles, like other
amphibians, are
sensitive to changes in
water quality. Some
species remain in this
vulnerable stage for 2
or 3 years.
When a tadpole’s legs appear it is called a
froglet. Occasionally froglets are found with
mutations caused by contaminants.
If the contamination is sufficient, adult frogs
will not be observed or will be less
numerous, since the egg, tadpole or froglet
stage has been harmed by pollutants or
toxins.
PAINTED TURTLE
Painted turtles basking in the
sun.
Turtles are not as sensitive as frogs are
to changes in abiotic factors that cause
negative ecological impacts. This is due
to the fact that reptile skin doesn’t
allow water to enter it as does
amphibian skin. Therefore amphibians
are better indicators of chemical
changes affecting aquatic ecosystem
health.
OUR MARSH BIRDS
Red-Winged
Blackbird
Mallard Duck
Ducks rely on native plants and
organisms as well. Ducks act to
recycle nutrients, spread seeds,
control insects, and provide food for
many species. Invasive species and
pollution affect our ducks as well
however, and some duck species are
decreasing in number as a result.
Great Blue Heron
Since the great blue heron is a
predator, it accumulates many of the
toxins present in the environment.
Because it preys mainly on aquatic
organisms, its fatty tissues can tell us
what contaminants may be a problem
in our aquatic ecosystem.
These birds need native wetland
plants to build their nests and
wetland insects to feed their young.
Unfortunately, invasive plant species
are taking over our wetlands,
harming many native species.
• Note that protochordates and echinoderms do not
occur in FW. Cirripedia in crustacean class does
not occur in FW. However, other many vertebrates
e.g. fish, amphibians, reptiles (snakes) and birds
which depend on water and mammals do occur in
FW.
• It has been noted that many fauna and floral
varieties occur more in marine than in FW.
• These aquatic organisms are divided into different
groups based on their micro-habitats. These
include:
• (a) Neustron – organisms resting on water
surfaces e.g. Gerris
• (b) Plankton – Live suspended in the water.
Sometimes called drifters or floaters because they
cannot control their movement but influenced by
water current e.g. the phytoplankton (plant-origin)
and zooplankton (animal-origin). Each member of
plankton is called plankter.
• (c) Nekton – organism which can control their
movement and swim in the water. They are macro-
organisms e.g Crustaceans, molluscs, fishes.
• Plankton and Nekton are grouped together as
pelagic or limnetic organisms because they live
within the water column i.e. below the surface of
water and above the bottom.
• (d) Benthos – organisms which live in or on the
bottom of the water.
• Apart from all these, some organisms live attached
to plants e.g. Hydra. This is called periphyton.
Some are attached to rocks inside the water called
Aufwuch.
Phytoplankton are divided into 5 groups as:
• i. Diatomaceae
• ii. Myxophyceae
• iii. Dinophyceae
• iv. Euglenoceae
• v. Chlorophyceae
Zooplankton are divided into
• i. Rotifera
• ii. Cladocera
• iii. Copepoda
• iv. Coelenterata
• v. Protozoa
Features of biological success of planktonic
organisms
• i. Members have very high surface area to volume
ratio. This leads to an increase in frictional force
which decreases the rate of sinking of the organism.
• ii. Cyclomorphosis is a process whereby planktonic
organisms exhibit changes in length of their
appendages (spines) with the density of water e.g..
• Ceratium shortens its spine during winter when
density is high as it needs less energy to keep afloat.
afloat. During summer when density is low, Ceratium
• v. Planktonic organisms exhibit patchiness
whereby they are not evenly distributed to reduce
pressure from predators.
• vi. Plankton shows seasonality in abundance. This
depends on change in water current, water level,
transparency and amount of nutrients available
i.e. conductivity.
• vii. Most of the animal plankton are transparent
which provide protection from the predators.
• viii. Planktonic organisms show diurnal ventral
migration.
• Nekton – are fishes and crustaceans mainly. So
also molluscs.
• Benthos – Occur at the bottom of water, include
bacteria and fungi, protozoan, leeches,
oligochaetes, planarians, ostracods, crabs and
prawns, coleopterans. They are many snails.
• Periphyton include Hydra which attach to plants,
water mites and rotifers.
• Neustron – stay at surface of the water. These are
mainly arthropods – Gyrinus, Gerris (Pond skater),
adult mosquito (temporarily).
PLANTS
• a. Floating plants – float freely on water e.g. Pistia,
Lemna Salvinia
• b. Submerged Vegetation – Plants completely
under water e.g. Ceratophyllu, Utricularia
• c. Rooted vegetation – Have roots at the bottom
but leaves appear on the surface of water e.g.
grasses and sedges
YELLOW POND OR BULLHEAD LILY
Leaves float on
the surface of
the water,
absorbing
sunlight and
shading the
water.
This reduces
warming and
algal growth.
The leaves also
provide great
cover for
wetland
organisms!
MARSH PLANTS ARE AMAZING!
Plants like cattail prevent
flooding by acting like sponges
to store excess water.
Cattail also let water out of their
tissues during droughts when
the water levels are low.
Marsh plants hold the soil in
place to prevent erosion.
Marsh plants act as filters to
soak up and store lots of the
chemicals we dump into the
water.
Native wetland plants also
provide habitat for huge
numbers of wildlife!
UNDERWATER VEGETATION
Many plants inhabit the
subsurface waters of aquatic
ecosystems.
Elodea is one example of an
underwater plant that produces
large amounts of dissolved
oxygen for aquatic life forms.
This plant acts to clean the water
and remove large amounts of
carbon dioxide.
Submerged plants also produce
food and shelter for many types
of wildlife.

More Related Content

Similar to Limnology and Wetland Management 2023 NaRM.pptx

Thesis de asis zubiaga_phytoplankton
Thesis de asis zubiaga_phytoplanktonThesis de asis zubiaga_phytoplankton
Thesis de asis zubiaga_phytoplanktonJahzeel Zubiaga
 
Environmental studies-AQUATIC ECOSYSTEM,THEIR TYPES AND THEIR IMPORTANCE.
Environmental studies-AQUATIC ECOSYSTEM,THEIR TYPES AND THEIR IMPORTANCE.Environmental studies-AQUATIC ECOSYSTEM,THEIR TYPES AND THEIR IMPORTANCE.
Environmental studies-AQUATIC ECOSYSTEM,THEIR TYPES AND THEIR IMPORTANCE.pkeditz
 
Paleoecology_Paleolimnology _ Encyclopedia.com.pdf
Paleoecology_Paleolimnology _ Encyclopedia.com.pdfPaleoecology_Paleolimnology _ Encyclopedia.com.pdf
Paleoecology_Paleolimnology _ Encyclopedia.com.pdfArvindKumar904250
 
Remote Sensing Techniques for Oceanography Satelitte and In Situ Observations
Remote Sensing Techniques for Oceanography Satelitte and In Situ ObservationsRemote Sensing Techniques for Oceanography Satelitte and In Situ Observations
Remote Sensing Techniques for Oceanography Satelitte and In Situ ObservationsA.Tuğsan İşiaçık Çolak
 
Elements of sea water (aem 215)
Elements of sea water (aem 215)Elements of sea water (aem 215)
Elements of sea water (aem 215)soumya sardar
 
earths hydrosphere and water pollution
earths hydrosphere and water pollutionearths hydrosphere and water pollution
earths hydrosphere and water pollutioncharmainebaduria
 
Plankton diversity and aquatic ecology of a freshwater lake (L3) at Bharti Is...
Plankton diversity and aquatic ecology of a freshwater lake (L3) at Bharti Is...Plankton diversity and aquatic ecology of a freshwater lake (L3) at Bharti Is...
Plankton diversity and aquatic ecology of a freshwater lake (L3) at Bharti Is...GJESM Publication
 
Marine and coastal ecosystems – overview.pptx
Marine and coastal ecosystems – overview.pptxMarine and coastal ecosystems – overview.pptx
Marine and coastal ecosystems – overview.pptxlavkushmaurya0017
 
FISHERY RESOURCES MAEGEMENT
FISHERY RESOURCES MAEGEMENTFISHERY RESOURCES MAEGEMENT
FISHERY RESOURCES MAEGEMENTbadlongn
 
Humanajd!!!!!
Humanajd!!!!!Humanajd!!!!!
Humanajd!!!!!badlongn
 
Factors influencing distribution of nutrition elements in sea
Factors influencing distribution of nutrition elements in seaFactors influencing distribution of nutrition elements in sea
Factors influencing distribution of nutrition elements in seaNazmul Ahmed Oli
 

Similar to Limnology and Wetland Management 2023 NaRM.pptx (20)

Thesis de asis zubiaga_phytoplankton
Thesis de asis zubiaga_phytoplanktonThesis de asis zubiaga_phytoplankton
Thesis de asis zubiaga_phytoplankton
 
Limnology
LimnologyLimnology
Limnology
 
Environmental studies-AQUATIC ECOSYSTEM,THEIR TYPES AND THEIR IMPORTANCE.
Environmental studies-AQUATIC ECOSYSTEM,THEIR TYPES AND THEIR IMPORTANCE.Environmental studies-AQUATIC ECOSYSTEM,THEIR TYPES AND THEIR IMPORTANCE.
Environmental studies-AQUATIC ECOSYSTEM,THEIR TYPES AND THEIR IMPORTANCE.
 
Paleoecology_Paleolimnology _ Encyclopedia.com.pdf
Paleoecology_Paleolimnology _ Encyclopedia.com.pdfPaleoecology_Paleolimnology _ Encyclopedia.com.pdf
Paleoecology_Paleolimnology _ Encyclopedia.com.pdf
 
Ecology 3
Ecology 3Ecology 3
Ecology 3
 
Junk&wantzen 1989 update_new flood pulse
Junk&wantzen 1989 update_new flood pulseJunk&wantzen 1989 update_new flood pulse
Junk&wantzen 1989 update_new flood pulse
 
Limnology 2nd sem (full sylabus)
Limnology 2nd sem (full sylabus)Limnology 2nd sem (full sylabus)
Limnology 2nd sem (full sylabus)
 
Remote Sensing Techniques for Oceanography Satelitte and In Situ Observations
Remote Sensing Techniques for Oceanography Satelitte and In Situ ObservationsRemote Sensing Techniques for Oceanography Satelitte and In Situ Observations
Remote Sensing Techniques for Oceanography Satelitte and In Situ Observations
 
Aquatic ecosystem
Aquatic ecosystemAquatic ecosystem
Aquatic ecosystem
 
Elements of sea water (aem 215)
Elements of sea water (aem 215)Elements of sea water (aem 215)
Elements of sea water (aem 215)
 
earths hydrosphere and water pollution
earths hydrosphere and water pollutionearths hydrosphere and water pollution
earths hydrosphere and water pollution
 
Classification of lakes
Classification of lakes Classification of lakes
Classification of lakes
 
Plankton diversity and aquatic ecology of a freshwater lake (L3) at Bharti Is...
Plankton diversity and aquatic ecology of a freshwater lake (L3) at Bharti Is...Plankton diversity and aquatic ecology of a freshwater lake (L3) at Bharti Is...
Plankton diversity and aquatic ecology of a freshwater lake (L3) at Bharti Is...
 
Aquatic ecosystems
Aquatic ecosystemsAquatic ecosystems
Aquatic ecosystems
 
Marine and coastal ecosystems – overview.pptx
Marine and coastal ecosystems – overview.pptxMarine and coastal ecosystems – overview.pptx
Marine and coastal ecosystems – overview.pptx
 
FISHERY RESOURCES MAEGEMENT
FISHERY RESOURCES MAEGEMENTFISHERY RESOURCES MAEGEMENT
FISHERY RESOURCES MAEGEMENT
 
Humanajd!!!!!
Humanajd!!!!!Humanajd!!!!!
Humanajd!!!!!
 
Plankton in the Sea.ppt
Plankton in the Sea.pptPlankton in the Sea.ppt
Plankton in the Sea.ppt
 
Factors influencing distribution of nutrition elements in sea
Factors influencing distribution of nutrition elements in seaFactors influencing distribution of nutrition elements in sea
Factors influencing distribution of nutrition elements in sea
 
Presentation
PresentationPresentation
Presentation
 

Recently uploaded

In vitro evaluation of antibacterial activity of chloroform extract Andrograp...
In vitro evaluation of antibacterial activity of chloroform extract Andrograp...In vitro evaluation of antibacterial activity of chloroform extract Andrograp...
In vitro evaluation of antibacterial activity of chloroform extract Andrograp...Open Access Research Paper
 
TEST BANK For Geosystems An Introduction to Physical Geography, 5th Canadian ...
TEST BANK For Geosystems An Introduction to Physical Geography, 5th Canadian ...TEST BANK For Geosystems An Introduction to Physical Geography, 5th Canadian ...
TEST BANK For Geosystems An Introduction to Physical Geography, 5th Canadian ...marcuskenyatta275
 
2024-05-16 Composting at Home 101 without link to voucher
2024-05-16 Composting at Home 101 without link to voucher2024-05-16 Composting at Home 101 without link to voucher
2024-05-16 Composting at Home 101 without link to voucherEllen Book
 
LaPlace Transforms 2 with use of Matlab.pptx
LaPlace Transforms 2 with use of Matlab.pptxLaPlace Transforms 2 with use of Matlab.pptx
LaPlace Transforms 2 with use of Matlab.pptxjoshuaclack73
 
一比一原版(Monash毕业证)莫纳什大学毕业证成绩单
一比一原版(Monash毕业证)莫纳什大学毕业证成绩单一比一原版(Monash毕业证)莫纳什大学毕业证成绩单
一比一原版(Monash毕业证)莫纳什大学毕业证成绩单qogbuux
 
LaPlace Transform Questions.pptjjjjjjjjjx
LaPlace Transform Questions.pptjjjjjjjjjxLaPlace Transform Questions.pptjjjjjjjjjx
LaPlace Transform Questions.pptjjjjjjjjjxjoshuaclack73
 
The Key to Sustainable Energy Optimization: A Data-Driven Approach for Manufa...
The Key to Sustainable Energy Optimization: A Data-Driven Approach for Manufa...The Key to Sustainable Energy Optimization: A Data-Driven Approach for Manufa...
The Key to Sustainable Energy Optimization: A Data-Driven Approach for Manufa...Aggregage
 
poplar trees field in kurdistan region of iraq.pptx
poplar trees field in kurdistan region of iraq.pptxpoplar trees field in kurdistan region of iraq.pptx
poplar trees field in kurdistan region of iraq.pptxjihad19
 
ecosystem class 12 ppt investigatory project
ecosystem class 12 ppt investigatory projectecosystem class 12 ppt investigatory project
ecosystem class 12 ppt investigatory projectMayank524181
 
WhatsUpp In... Alpine Region concerning Hydrogen Valleys - 16 mai 2024
WhatsUpp In... Alpine Region concerning Hydrogen Valleys - 16 mai 2024WhatsUpp In... Alpine Region concerning Hydrogen Valleys - 16 mai 2024
WhatsUpp In... Alpine Region concerning Hydrogen Valleys - 16 mai 2024Cluster H2O
 
Climate change Presentation for students who need it
Climate change Presentation for students who need itClimate change Presentation for students who need it
Climate change Presentation for students who need itmaythadar1312
 
NO1 Best Amil Baba In Pakistan Authentic Amil In pakistan Best Amil In Pakist...
NO1 Best Amil Baba In Pakistan Authentic Amil In pakistan Best Amil In Pakist...NO1 Best Amil Baba In Pakistan Authentic Amil In pakistan Best Amil In Pakist...
NO1 Best Amil Baba In Pakistan Authentic Amil In pakistan Best Amil In Pakist...Amil baba
 
New Metrics for Sustainable Prosperity: Options for GDP+3
New Metrics for Sustainable Prosperity: Options for GDP+3New Metrics for Sustainable Prosperity: Options for GDP+3
New Metrics for Sustainable Prosperity: Options for GDP+3susannedejong
 
Laplace Transforms.pptxhhhhhhhhhhhhhhhhh
Laplace Transforms.pptxhhhhhhhhhhhhhhhhhLaplace Transforms.pptxhhhhhhhhhhhhhhhhh
Laplace Transforms.pptxhhhhhhhhhhhhhhhhhjoshuaclack73
 
New Metrics for Sustainable Prosperity: Options for GDP+3 (preliminary study)
New Metrics for Sustainable Prosperity: Options for GDP+3 (preliminary study)New Metrics for Sustainable Prosperity: Options for GDP+3 (preliminary study)
New Metrics for Sustainable Prosperity: Options for GDP+3 (preliminary study)susannedejong
 
Plastic angel or demon/recycling process
Plastic angel or demon/recycling processPlastic angel or demon/recycling process
Plastic angel or demon/recycling processMustafa Alp
 
Learn Creative Upcycling Ideas for Old T-Shirts: Transform Your Wardrobe Now
Learn Creative Upcycling Ideas for Old T-Shirts: Transform Your Wardrobe NowLearn Creative Upcycling Ideas for Old T-Shirts: Transform Your Wardrobe Now
Learn Creative Upcycling Ideas for Old T-Shirts: Transform Your Wardrobe NowSwag Cycle
 
Lecture 6- Bacteria- Pathathogenesis.ppt
Lecture 6- Bacteria- Pathathogenesis.pptLecture 6- Bacteria- Pathathogenesis.ppt
Lecture 6- Bacteria- Pathathogenesis.pptDiptiPriya6
 
Multiple choice Qs - Construction safety
Multiple choice Qs - Construction safetyMultiple choice Qs - Construction safety
Multiple choice Qs - Construction safetyAnilDamahe1
 
LANDFILL AND ITS EFFECT(Managing waste).pptx
LANDFILL AND ITS EFFECT(Managing waste).pptxLANDFILL AND ITS EFFECT(Managing waste).pptx
LANDFILL AND ITS EFFECT(Managing waste).pptxKrish DS
 

Recently uploaded (20)

In vitro evaluation of antibacterial activity of chloroform extract Andrograp...
In vitro evaluation of antibacterial activity of chloroform extract Andrograp...In vitro evaluation of antibacterial activity of chloroform extract Andrograp...
In vitro evaluation of antibacterial activity of chloroform extract Andrograp...
 
TEST BANK For Geosystems An Introduction to Physical Geography, 5th Canadian ...
TEST BANK For Geosystems An Introduction to Physical Geography, 5th Canadian ...TEST BANK For Geosystems An Introduction to Physical Geography, 5th Canadian ...
TEST BANK For Geosystems An Introduction to Physical Geography, 5th Canadian ...
 
2024-05-16 Composting at Home 101 without link to voucher
2024-05-16 Composting at Home 101 without link to voucher2024-05-16 Composting at Home 101 without link to voucher
2024-05-16 Composting at Home 101 without link to voucher
 
LaPlace Transforms 2 with use of Matlab.pptx
LaPlace Transforms 2 with use of Matlab.pptxLaPlace Transforms 2 with use of Matlab.pptx
LaPlace Transforms 2 with use of Matlab.pptx
 
一比一原版(Monash毕业证)莫纳什大学毕业证成绩单
一比一原版(Monash毕业证)莫纳什大学毕业证成绩单一比一原版(Monash毕业证)莫纳什大学毕业证成绩单
一比一原版(Monash毕业证)莫纳什大学毕业证成绩单
 
LaPlace Transform Questions.pptjjjjjjjjjx
LaPlace Transform Questions.pptjjjjjjjjjxLaPlace Transform Questions.pptjjjjjjjjjx
LaPlace Transform Questions.pptjjjjjjjjjx
 
The Key to Sustainable Energy Optimization: A Data-Driven Approach for Manufa...
The Key to Sustainable Energy Optimization: A Data-Driven Approach for Manufa...The Key to Sustainable Energy Optimization: A Data-Driven Approach for Manufa...
The Key to Sustainable Energy Optimization: A Data-Driven Approach for Manufa...
 
poplar trees field in kurdistan region of iraq.pptx
poplar trees field in kurdistan region of iraq.pptxpoplar trees field in kurdistan region of iraq.pptx
poplar trees field in kurdistan region of iraq.pptx
 
ecosystem class 12 ppt investigatory project
ecosystem class 12 ppt investigatory projectecosystem class 12 ppt investigatory project
ecosystem class 12 ppt investigatory project
 
WhatsUpp In... Alpine Region concerning Hydrogen Valleys - 16 mai 2024
WhatsUpp In... Alpine Region concerning Hydrogen Valleys - 16 mai 2024WhatsUpp In... Alpine Region concerning Hydrogen Valleys - 16 mai 2024
WhatsUpp In... Alpine Region concerning Hydrogen Valleys - 16 mai 2024
 
Climate change Presentation for students who need it
Climate change Presentation for students who need itClimate change Presentation for students who need it
Climate change Presentation for students who need it
 
NO1 Best Amil Baba In Pakistan Authentic Amil In pakistan Best Amil In Pakist...
NO1 Best Amil Baba In Pakistan Authentic Amil In pakistan Best Amil In Pakist...NO1 Best Amil Baba In Pakistan Authentic Amil In pakistan Best Amil In Pakist...
NO1 Best Amil Baba In Pakistan Authentic Amil In pakistan Best Amil In Pakist...
 
New Metrics for Sustainable Prosperity: Options for GDP+3
New Metrics for Sustainable Prosperity: Options for GDP+3New Metrics for Sustainable Prosperity: Options for GDP+3
New Metrics for Sustainable Prosperity: Options for GDP+3
 
Laplace Transforms.pptxhhhhhhhhhhhhhhhhh
Laplace Transforms.pptxhhhhhhhhhhhhhhhhhLaplace Transforms.pptxhhhhhhhhhhhhhhhhh
Laplace Transforms.pptxhhhhhhhhhhhhhhhhh
 
New Metrics for Sustainable Prosperity: Options for GDP+3 (preliminary study)
New Metrics for Sustainable Prosperity: Options for GDP+3 (preliminary study)New Metrics for Sustainable Prosperity: Options for GDP+3 (preliminary study)
New Metrics for Sustainable Prosperity: Options for GDP+3 (preliminary study)
 
Plastic angel or demon/recycling process
Plastic angel or demon/recycling processPlastic angel or demon/recycling process
Plastic angel or demon/recycling process
 
Learn Creative Upcycling Ideas for Old T-Shirts: Transform Your Wardrobe Now
Learn Creative Upcycling Ideas for Old T-Shirts: Transform Your Wardrobe NowLearn Creative Upcycling Ideas for Old T-Shirts: Transform Your Wardrobe Now
Learn Creative Upcycling Ideas for Old T-Shirts: Transform Your Wardrobe Now
 
Lecture 6- Bacteria- Pathathogenesis.ppt
Lecture 6- Bacteria- Pathathogenesis.pptLecture 6- Bacteria- Pathathogenesis.ppt
Lecture 6- Bacteria- Pathathogenesis.ppt
 
Multiple choice Qs - Construction safety
Multiple choice Qs - Construction safetyMultiple choice Qs - Construction safety
Multiple choice Qs - Construction safety
 
LANDFILL AND ITS EFFECT(Managing waste).pptx
LANDFILL AND ITS EFFECT(Managing waste).pptxLANDFILL AND ITS EFFECT(Managing waste).pptx
LANDFILL AND ITS EFFECT(Managing waste).pptx
 

Limnology and Wetland Management 2023 NaRM.pptx

  • 1. Limnology and Wetland Management NaRM3017 By: Tesfahun Tesema August,2023 18-Apr-24 1
  • 2. 1. Introduction 1.1. Definitions and Concepts of Limnology • Limnology – is the study of inland water; it includes some waters more saline than the ocean, ponds, streams, rivers, to lakes and reservoirs – large and small. • It encompasses everything from the geologic origins of lakes to the development of a lake in prehistoric times (Paleolimnology) to the structure of food webs. • As do oceanographers, limnologists generally specialize in physical, chemical or biological limnology. 18-Apr-24 2
  • 3. 1.1. Definitions and Concepts of Limnology Cont,,, • The history of limnology has steadily evolved over the last 120 years, both conceptually and technically. • Beginning with Forel’s classic work on Lac Léman, published in three vol. (1892, 1895 and 1904), and Forbes’ classic work on lakes as microcosms (1887), scientific interest in limnology – which encompasses the physics, chemistry and biology of lakes and other inland water bodies – has continued to grow. 18-Apr-24 3
  • 4. 1.1. Definitions and Concepts of Limnology Cont,,, • Initially regarded as the science of lakes, limnology now encompasses freshwater and saline lakes in the inland of continents, and all physical, chemical and biological interactions in these ecosystems. • Chemical processes and mechanisms occurring in inland waters are highly dependent on the geochemistry of soils in drainage basins. 18-Apr-24 4
  • 5. 1.1. Definitions and Concepts of Limnology Cont,,, • Aquatic systems interact with their drainage basin in various sub-systems and components. • That concept and comprehensive studies on drainage basins in relation to lakes, rivers, reservoirs and wetlands are more recent • Baldi (1949), defined limnology as the scientific study of the interrelated processes and methods by which matter and energy are transformed in a lake. 18-Apr-24 5
  • 6. 1.2. Importance of limnology as a science The most important progress in limnology as a science over the last ten years has been the growing understanding of the dynamic ecology of aquatic systems and applications in solving problems of protection, conservation and restoration of lakes. Another important dev’t in it has been the ability to predict the trends and characteristics of lakes and reservoirs over time, especially in terms of controlling influences such as eutrophication and fish stock. 18-Apr-24 6
  • 7. 1.3. Contributions of limnology to theoretical ecology Throughout its history as a science, limnology has contributed significantly to the development of theoretical ecology. Contributions include: Community succession and factors that control it (studies of phytoplankton succession, development of the benthic community in different types on substrata, periphyton succession, and succession of fish communities); Evolution of communities (studies on eutrophication in lakes, restoration of eutrophic lakes and reservoirs); 18-Apr-24 7
  • 8. 1.3. Contributions of limnology to theoretical ecology Community diversity and spatial heterogeneity (studies of periphyton and phytoplankton in different ecosystems, aquatic insects, comparative studies on lakes, reservoirs and floodplains. Theory and studies of ecotones); Primary production and energy flow (studies on the primary productivity of phytoplankton, aquatic macrophytes and periphyton, feeding habits of zooplankton and fishes. Physiological responses of phytoplankton to light intensity and concentration of nutrients); 18-Apr-24 8
  • 9. 1.3. Contributions of limnology to theoretical ecology Distribution of organisms and factors that control dispersal and colonization mechanisms (studies on the vertical migration of zooplankton, vertical distribution of phytoplankton, colonization in reservoirs and temporary waters, distribution of aquatic organisms in lakes, rivers and reservoirs); Evolution of ecosystems (studies on eutrophication, reservoirs, monitoring reservoirs and alterations resulting from human activities). 18-Apr-24 9
  • 10. 1.4. Branches of Limnology 18-Apr-24 10
  • 11. 1.4. Branches of Limnology Limnology is the study of the structural and functional interrelationships of organisms of inland waters as they are affected by their dynamic physical, chemical, and biotic environments. Physical limnology deals with the physical properties of the water in lakes and rivers. This includes changes in light levels, water temperatures, and water currents. Geology of basin (origin, morphology, leaching minerals) 18-Apr-24 11
  • 12. 1.4. Branches of Limnology Biological Limnology It is designed to provide an in depth understanding of the principles and paradigms of aquatic ecosystems and their watersheds. Base is photosynthesis - primary productivity Regulated by, and may regulate, physical and chemical factors 18-Apr-24 12
  • 13. 1.4. Branches of Limnology Chemical limnology It focuses on the cycling of various chemical substances in lakes and rivers. Several factors affect the chemistry of lakes and rivers including the chemical composition of the soil in the watershed, the atmosphere (mass of air surrounding Earth) and the composition of the riverbed or lake bottom. 18-Apr-24 13
  • 14. 1.4.1. Physical Limnology Properties of Water Water is an extremely unusual substance. It exists in three states: solid, liquid and gas. The transition from one phase to another depends on a rearrangement of the molecules and the configuration of its aggregates. 18-Apr-24 14
  • 15. 1.4.1. Physical Limnology Cont… Properties of Water The physical properties of water, especially its temperature- related anomalies in density, play a key role in the circulation and stratification processes in lakes and reservoirs, and in the vertical organization of the system in temperate lakes in winter, when surfaces freeze. Those properties of water, particularly its anomalies in density, surface tension and thermal features, are important to aquatic organisms inhabiting the liquid medium. 18-Apr-24 15
  • 16. 1.4.1. Physical Limnology Cont… Properties of Water The essential life processes of all organisms depend on water. Water is the universal solvent carrying the dissolved gases, elements, substances, and organic compounds that form the basis of all plant and animal life on the planet. Hydrogen in water functions as a source of electrons in photosynthesis. Water’s unique properties are related to its atomic structure, intermolecular hydrogen bonds and the molecular associations in the solid, liquid and gas phases. 18-Apr-24 16
  • 17. 1.4.1. Physical Limnology Cont… Properties of Water Oxygen is highly electronegative; in water, the oxygen atom binds with two hydrogen atoms that retain a +ve charge. Because water is a strong dipole with two hydrogen atoms (positive) and one oxygen atom (negative), in addition to the distance (as charge x distance), there are significant effects on water’s physical properties. Without this strong dipolar feature, water would not be liquid. 18-Apr-24 17
  • 18. 1.4.1. Physical Limnology Cont… Importance of water’s physical and chemical properties for aquatic organisms oThe entire life cycle and behaviour of aquatic organisms are influenced by the physical and chemical properties of water, especially its density, anomalies of density, thermal properties and capacity as a universal solvent. oThe surface tension of water, which also has great biological significance, varies with temperature and the concentration of dissolved solids. 18-Apr-24 18
  • 19. 1.4.1. Physical Limnology Cont… Importance of water’s physical and chemical properties for aquatic organisms oWater’s surface tension enables a set of organisms – neuston or pleuston – to utilize the interface between the water and the atmosphere for support as well as for movement. oAnother biologically important property of water is its dynamic viscosity, which is the force required to move 1 kg a distance of 1 meter in 1 second through a mass of water. oIt depends on the temp. of the water and its salt content. 18-Apr-24 19
  • 20. 1.4.1. Physical Limnology Cont… No Property Comparison with other substances Importance to aquatic systems 1 Density Under standard pressure maximum density is at 3.94 0C, not 0 0C; expands upon freezing Allows lake stratification, and surface freezing rather than bottom freezing 2 Melting and boiling points Both properties unusual; very high Allows water to exist as a liquid 3 Viscosity Moderate Influences the case of water mixing, provides resistance to the movement of organisms, and helps determine the sedimentation rate of particles 4 Specific Heat capacity Highest of any liquid, other than ammonia Moderates ( Buffers) temperature extremes 18-Apr-24 20
  • 21. 1.4.1. Physical Limnology Cont… No Property Comparison with other substances Importance to aquatic systems 5 Heat of Vaporizati on One of the highest known Important to heat transfer in inland water and atmosphere 6 Surface tension Very high Increases the difficulty of surface waves breaking and thereby slowing the rate of heating and cooling in lakes, allows certain insects to walk on water surfaces 7 Absorptio n of radiation Large in infrared region, but moderate in the photosynthetic / visible region Allows greater heat absorption in the surface water, but reduced surface absorption at shorter wavelengths, allowing a greater penetration of photosynthetically available radiation 8 Solvent Propertie s Dipolar nature makes it excellent solvent for salts and other polar molecules Important in dissolution and transport of dissolved substances from catchments and atmosphere to aquatic systems 18-Apr-24 21
  • 22. 1.4.1. Physical Limnology Cont… I. Water and Heat Most important physical property of water is it’s Heat Capacity. Specific heat is the amount of heat needed to raise or lower the temperature of 1g of substance by 1 degree Celsius It’s unusual thermal characteristics – Prevent wide temperature variations from day to night and from summer to winter Permit vast amounts of heat to flow from equatorial to polar areas and Power earth’s great storms, winds 18-Apr-24 22
  • 23. 1.4.1. Physical Limnology Cont… • The specific heat of water is higher than nearly all other liquids. • It takes 4.187 J (one calorie ) to heat 1 g (1cm 3) of pure water by 1 °C (at 15 °C ). • The high specific heat of water, as well as a high latent heat of evaporation, is a function of the relatively large amounts of heat energy required to disrupt the hydrogen bonding of liquid water molecules. 18-Apr-24 23
  • 24. 1.4.1. Physical Limnology Cont… • These heat-requiring and heat-retaining properties of water provide a much more stable environment than is found in terrestrial situations. • Fluctuations in water temperature occur very gradually. • Daily and seasonal extremes in temperature are small in comparison to those of aerial habitats. • The high specific heat of water can also have profound effects on climatic conditions of adjacent air and land masses. 18-Apr-24 24
  • 25. 1.4.1. Physical Limnology Cont… • The specific heat (thermal capacity) of ice below 0°C is about half (0.5/g/°C) that of water and decreases progressively at temperatures below 0°C. • The amount of heat required, however, to change ice to liquid water is large (latent heat of melting =79.72 cal/g) and is very much larger for disruption of hydrogen bonding in evaporation of water (latent heat of evaporation — 540 cal/g) or for direct sublimation of ice to water vapor (latent heat of sublimation = 679 cal/g). 18-Apr-24 25
  • 26. 1.4.1. Physical Limnology Cont… • Conversely but similarly, a large amount of heat must be lost for the fusion of molecules of 0°C water to ice (latent heat of fusion = 79.72 cal/g). • Because of these properties, large energy inputs are required to melt ice in the spring, and large energy losses are required in order to form ice cover in the winter. 18-Apr-24 26
  • 27. 1.4.1. Physical Limnology Cont… Inland Water Bodies • The inland waters which include both fresh water masses and estuarine waters of varying salt content are clearly distinguishable from the salt waters of the oceans. • The inland water masses are discrete and being isolated within the specific land area, acquire the characteristic chemical composition of the land, by exchange between soil and water. 18-Apr-24 27
  • 28. 1.4.1. Physical Limnology Cont… • The oceanic water on the other hand is open and mixing together by wind action and currents and therefore more homogeneous in chemical composition. • However, the land water exchange is limited to coastal areas. • The estuarine waters are mixtures of sea and freshwater, but with the higher content of salts in the sea water (150 – 200 times that of freshwater), are dominated by the sea water effects. 18-Apr-24 28
  • 29. 1.4.1. Physical Limnology Cont… • According to Hutchinson (1959), limnology is the large variety, individual and groups of inland water bodies, the diversity being caused by the diversity of their origin as well as by the diversity of their chemistry and biology. Types of inland water • Frey (1960) has classified inland waters in three different ways viz, depending on whether the water is stationary or flowing, depending on whether the water mass is natural or artificial and permanent / temporary. 18-Apr-24 29
  • 30. 1.4.1. Physical Limnology Cont… a. Flowing waters (Lotic waters) • These include creeks, streams and rivers mentioned in that sequence because of their sequence of succession also in the same order, through the natural processes of lengthening and widening of running waters. • In these, there is continuous current of water in one direction. • The organisms inhabiting these waters have complexity of adaptation towards the increase in water current speed. 18-Apr-24 30
  • 31. 1.4.1. Physical Limnology Cont… b. Standing waters (Lentic waters) • Here, water current is not a major ecological factor; unlike in the lotic series lakes, ponds and swamps form the lentic series. • It includes all forms of inland waters – lakes, ponds, swamps and their various intergrades in which the water does not flow continuously in definite directions. • Essentially, the water remains standing, though a certain amount of water mov’t may occur, such as wave action, internal currents or flow of water in the vicinity of inlets and 18-Apr-24 31
  • 32. 1.4.1. Physical Limnology Cont… Inland waters and the water cycle • Most of inland water bodies are freshwater and they account only for a small fraction (~0,0.2%) of the whole hydrosphere. • Some more freshwater (~1%) is groundwater and the ~2% of the hydrosphere is confined as ice in polar caps and in glaciers. • Most of the water on Earth (~97%) is made up by seawater. • In spite of the uncertainty of these estimates, without doubt the usable freshwater allowing for the existence of life on the continents is a very small fraction of the hydrosphere. 18-Apr-24 32
  • 33. 1.4.1. Physical Limnology Cont… Inland waters and the water cycle • The mechanism supplying new freshwater to continents as the water flows away from them is the water cycle • The sun provides the energy that keeps the water cycle moving through the evaporation of oceanic and inland surface waters and the evapotranspiration of terrestrial vegetables. • Water vapor then progressively condensate in the atmosphere, eventually returning to the ground as rain or snow. 18-Apr-24 33
  • 34. 1.4.1. Physical Limnology Cont… 18-Apr-24 34
  • 35. 1.4.1. Physical Limnology Cont… Lakes • Lakes are depressions surrounded by land and hold standing fresh or saline water all year round. • Lakes are also described as water bodies that are larger than ponds, have wave action on the shoreline, or where wind- induced turbulence plays a major role in mixing the water column. • Lakes are bodies of water enclosed by land. • Lakes are created by natural or human–initiated processes. 18-Apr-24 35
  • 36. 1.4.1. Physical Limnology Cont… Origin of Lakes • Lakes’ origins and morphometry play an important role in their physical, chemical and biological processes, since, along with regional climatic processes, these factors contribute to the functioning of the lakes. • The study of geomorphology contributes significantly to understanding the origin of lakes and the dynamics of the formative processes of lake ecosystems. • Morphology, the study of lake shapes, is related to the origins of each system. 18-Apr-24 36
  • 37. 1.4.1. Physical Limnology Cont… • Morphometry deals with the quantification of these forms and elements. • Lake morphology and morphometry basically depend on the processes from which lakes originated. • All inland water systems originated from a variety of natural processes and diverse formative mechanisms that vary from region to region and from one geologic era to another. • Because most lakes in an area have the same origin, we refer to “lake districts” 18-Apr-24 37
  • 38. 1.4.1. Physical Limnology Cont… Formation of Lakes:- Tectonic/Rift-Valley • The lake is formed by movements of the Earth’s crust, such as faults that result in depressions. They are often formed in rift valleys (graben). • Well-known examples are Lake Baikal (Siberia), Lake Tanganyika (Africa) and Lake Victoria (Africa), which was facilitated by the obstruction of the Kagera and Katonga Rivers, creating a 68,422-sq.km basin. • List Rift-Valley Lakes of Ethiopia. 18-Apr-24 38
  • 39. 1.4.1. Physical Limnology Cont… • Tectonic movements can occur through the emergence or subsiding (lifting or sinking) of areas with shifts in sea level. • The formation of lakes then begins with isolation from the ocean. Volcanic Lakes • The formation of depressions, or hollows that do not drain naturally, produces a series of volcanic lakes. • Volcanoes are common in areas where tectonic mov’ts occur. • Identify lakes of Ethiopia, that are volcanic in origin. 18-Apr-24 39
  • 40. 1.4.1. Physical Limnology Cont… • Lava discharged by active volcanoes can obstruct a river and form lakes. • Examples include some usually small lakes in Africa, Asia, Japan and New Zealand. Glaciation • Many present-day lakes were formed by glacial action. • These movements, which can be catastrophic, cause deposits or corrosion of masses of ice and their depositions, with subsequent thawing. 18-Apr-24 40
  • 41. 1.4.1. Physical Limnology Cont… Solution lakes • Many lakes are formed when deposits of soluble rock are gradually dissolved by percolating water. • For example, solution lakes are formed by the dissolution of CaCO3 from slightly acidic water containing CO2. Lakes formed by fluvial activity • Rivers, as they flow, have an obstructive capacity (due to deposition of sediments) and an erosive capacity (due to transport of sediment). 18-Apr-24 41
  • 42. 1.4.1. Physical Limnology Cont… • Many lateral lakes are formed by the activity of rivers depositing sediments that obstruct tributaries. Lakes formed by wind action • Depressions formed by wind action, or blocked by accumulation of dunes, can also lead to the formation of lakes. • Such lakes are ephemeral, since hollows thus formed retain water only during rainy periods, and become increasingly saline due to evaporation in the dry season, and, finally, they dry up. 18-Apr-24 42
  • 43. 1.4.1. Physical Limnology Cont… Lakes formed by organic deposits • The growth of plants and associated detritus can cause obstructions in small rivers and depressions. Landslides • Large-scale movements of rock or soil, resulting from abnormal weather events such as excessive rainfall or the action of earthquakes, can produce lakes by blocking valleys. Such lakes are usually temporary, due to rapid erosion that occurs in the unconsolidated dam. 18-Apr-24 43
  • 44. 1.4.1. Physical Limnology Cont… Coastal lagoons • Deposition of material on the coast, produced in regions where there are bays or inlets, can lead to the creation of coastal lakes. Lakes of meteoric origin • On rare occasions a meteorite striking the Earth’s surface can lead to a depression that later accumulates water, forming a lake. 18-Apr-24 44
  • 45. 1.4.1. Physical Limnology Cont… Multi-origin lakes • Several of the processes described – such as glaciation, heavy precipitation, and tectonic movement – can interact and lead to the formation of a lake or a complex of lakes. • To understand the origins and formation of lakes, it is first necessary to determine their bathymetry and varying depths. 18-Apr-24 45
  • 46. 1.4.1. Physical Limnology Cont… Lake Classification According to their Richness • Oligotrophic lakes are nutrient-poor lakes of glacial origins with underlying rocks made up mainly of granite. • Mesotrophic lakes have balanced nutrient status but their depths usually allow thermal stratification most times of the year causing differences in abundance of nutrients, phytoplankton and zooplankton e.g. Rift valley Lakes. • Eutrophic lakes are nutrient-enriched e.g. depression lakes. They usually have intensive agricultural activities around them. 18-Apr-24 46
  • 47. 1.4.1. Physical Limnology Cont… Classification of Lakes According to Mixing or Stratification Features • According to their mixing features lakes can be classified as: • Holomictic lakes are those completely mix because they reach uniform temperature and density from top to bottom. • Full circulation or mixing can occur once or twice a year. • Monomictic lakes mix from top to the bottom during one mixing period each year. There are two types of monomictic lakes namely cold and warm. 18-Apr-24 47
  • 48. 1.4.1. Physical Limnology Cont… • Dimictic lakes mix from top to bottom during two mixing periods in the year-spring and autumn. • Polymictic lakes are also holomictic lakes that mix several times a year. • They are too shallow to develop thermal stratification and their waters mix from top to bottom throughout the year. • Oligomictic lakes have irregular mixing, which may not occur every year. 18-Apr-24 48
  • 49. 1.4.1. Physical Limnology Cont… • Amictic lakes are lakes that never circulate or mix. Amictic lakes are usually ice covered throughout the year. • Water temperature in the lake increase with depth (inverse cold water stratification).????????????????? • Meromictic lakes are those in which bottom water never mixes with surface water. • In these lakes, dissolved substances accumulate at the bottom, increasing the water density above the value attributable to temperature alone. 18-Apr-24 49
  • 50. 1.4.1. Physical Limnology Cont… Zonation in Lakes • According to light and temperature distribution in a lake, there are zones with different characteristics in lakes. These are commonly used in limnological context. 18-Apr-24 50
  • 51. 1.4.1. Physical Limnology Cont… 18-Apr-24 51
  • 52. 1.4.1. Physical Limnology Cont… The zones of a Lake are: • Littoral Zone: Is the portion of the lake horizontally extending from the shore to the point impending the bottom area where submerged macrophytes and benthic algae can live. • This is the part of the lake bottom reached by solar radiation, included in the photic zone. • Pelagic Zone: Is the portion of the lake above the depths not reached by solar radiation. 18-Apr-24 52
  • 53. 1.4.1. Physical Limnology Cont… • Photic or Euphotic Zone: Is the layer of water vertically extending from the surface to the depth reached by 1% of surface solar radiation. • Aphotic Zone: Is the part of the water column not reached by solar radiation. • Epilimnion/Hypolimnion: water layers overlying or underlying the thermocline. • Thermocline or Metalimnion: Is the layer of water where the temperature changes of 1°C per meter. 18-Apr-24 53
  • 54. 1.4.1. Physical Limnology Cont… • Benthic Zone: is the portion of the lake located at the water sediment interface. • In the aphotic zone it is often called profound benthic zone. 18-Apr-24 54
  • 55. Morphology of Lake Basins • The shape and size of a lake basin affect nearly all physical, chemical, and biological parameters of lakes. • The forms of lake basins are extremely varied and reflect their modes of origin, how water movements have subsequently modified the basin, and the extent of loading of materials from the surrounding drainage basin. • The morphometry of a lake is best described by a bathymetric map, which is required for the determination of all major morphometric parameters.
  • 56. Morphology and Morphometry of Lakes • Such a map is prepared by a survey of the shoreline by standard surveying methods, often in combination with aerial photography. • From the map of the shore line a detailed bathymetric map of depth contours must be constructed from a series of accurate depth soundings along intersecting transects (Wetzel, 2001) Morphometric parameters. • Area (km2) A • Volume V • Maximum length Lmax • Maximum width Lamax
  • 57. Surface area: grid method You’ll need: • Bathymetric map • Grid paper Method: • Count up the number of squares that fall within the shoreline of the lake • Use the map scale to determine area represented by each square scale Area = # squares counted X area of one square
  • 58. Atop Abottom z z z Calculating Lake Volume Atop = the area at the top of the layer Abottom = the area at the bottom of the layer z = the distance between contour lines V = the volume of one layer   3 bottom top A A A A z V bottom top    
  • 59. Chapter One Cont… Maximum length (Lmax) and maximum width (Lamax) • The maximum length of a lake is determined based on maps or aerial photographs or satellite images. • It is the distance between the two furthest points of the lake in a straight line. • The maximum effective length has an important hydrographic and limnological application, because it corresponds to the maximum distance between two uninterrupted points on the lake or reservoir.
  • 60. Average depth (Z) • The average depth is determined by dividing the lake’s volume (V) by its area (A). • It is an important parameter because the lake’s biological productivity is generally related to its average depth. Relative Depth (Zr) • It is given as a percentage and is defined by the ratio of the lake’s maximum depth (Zmax) and average diameter. • The greater the depth, the more probable it is that the lake presents more stable thermal stratification.
  • 61. Perimeter (m) • The perimeter corresponds to measurements of the lake’s contour, and can be obtained using maps or aerial photographs and measuring, by various techniques, the values of the perimeter in meters. Shoreline development index (DL) • The shoreline development index is a measure of the degree of irregularity of the shoreline. • It is the r/nship b/n the length of the shoreline and the length of a circumference of a circle with an area equal to that of the lake.
  • 62. Chapter One Cont… • It measures the degree of deviation of the lake or reservoir from a circular pattern. • The shoreline development index (DL) is given by:
  • 63. Chapter One Cont… Volume development index (Dv) • This indicator is used to express the type of lake basin and is defined as the ratio of the lake’s volume to the volume of a cone with a base area equal to the lake’s area and a height equal to the lake’s maximum depth. • The Dv is generally about three times the ratio Z:Zmax.
  • 64. Average slope (α) • The average slope (α) is determined by the formula: • Identifying a lake’s bathymetric profile is also an important factor because of the relationship between irregularities and depressions and circulation. • These depressions can alter thermal and chemical conditions during the period of stratification.
  • 65. Chapter One Cont… • Knowledge of the shape of the lake is essential, because there is a relationship between the shape and circulation of waters and mechanisms in the functioning of lakes. • Significant morphological modifications can occur when a lake is subject to many impacts, especially from human activities. • E.g, deforestation in water basins can significantly alter a lake’s morphometry and morphology, due to suspended sediment.
  • 66. Morphology And Flow In River Ecosystems • The continual downgradient movement of water, dissolved substances, and suspended particles in streams and rivers is derived primarily from the land area draining into a given stream channel. • The hydrological, chemical, and biological characteristics of a stream or river reflect the climate, geology, and vegetational cover of the drainage basin
  • 67. River morphology • Meteoric water flowing down slopes ends up merging to form small streams which then channel into a river. • Because of the kinetic energy of the moving water, the river develops various landforms through channel processes. • The area supplying water into a river is the drainage basin (db). • The boundary b/n drainage basins is a water divide (wd). • A river system is composed of the main stream (ms) and many tributaries (t).
  • 68. • The main fluvial processes are erosion, transportation and sedimentation. • In the upper area of a drainage basin, where current velocity is higher, erosion predominates and valleys composed of channels and slopes are formed. • The materials swept downstream are the sediment load, produced mainly by weathering of the rocks composing slopes. • Sediment load is deposited to form an alluvial plain. • The channel patterns forming in alluvial plains can be braided, meandering and straight.
  • 69. • The channel patterns and forms bring about the river morphology, decided by many inter- related factors such as discharge, water velocity, slope, depth and width of the channel, and riverbed geology.
  • 70. Energy penetration in lakes • the spectrum of the solar radiation reaching lakes surface and the effect of different wavelengths on organic matter and living organisms. • The radiation of higher energies changes the atomic or molecular structure of matter. • With decreasing energy content, i.e. in the range of visible light, the radiation energy is used for photosynthesis, the biochemical reactions leading to organic matter production by autotrophic organisms.
  • 71. • Thus the radiation in the visible range 400-700 nm is called Photosynthetically Active Radiation (PAR). • The long wavelength radiation interacts with water molecules, transferring them its energy and determining the water heating. Figure 13. Spectrum and activity of solar radiation reaching the biosphere.
  • 72. • The amount of solar radiation reaching the surface of lakes varies depending on the transparency of the atmosphere, latitude and altitude of the lake. • When it reaches the lake surface, the radiation is partly reflected, returning to the atmosphere, and partly refracted, penetrating in the water. • The percentage of incident radiation reflected depends on the sun position according to day time and season, i.e. the incidence angle. • The percentage of radiation reflected is minimum when the sun is at zenith and maximum when the sun is near the horizon
  • 73. Lake water transparency • Particles and solutes present in a lake determine its transparency, which is assessed with the Secchi disk, a simple instrument firstly used in 1865 by abbot A. Secchi. • It is a white disk, usually metallic, 20-30 cm in diameter, tied to a rope. • The Secchi disk is lowered in water and the depths of its disappearance and reappearance are measured (Figure 15). • The average between the two measures is the transparency of a lake, defined as Secchi disk disappearance depth.
  • 74. Figure 15. Secchi disk in a transparent (left) and in a turbid lake (right). The arrows indicate the water level.
  • 75. Thermal energy and lakes circulation • The hydrodynamic of a lake is complex because of the complex interactions between water and the forces moving it. • Considering the heat content, affecting the density of lake waters and therefore their buoyancy, it is transferred: • - by radiation, when the energy transfer occurs via electromagnetic waves, without matter transfer • - by conduction, when heat is transferred through thermal energy exchange from one molecule to the next one, without mass movement.
  • 76. • This is possible when there is a temperature gradient between water masses • - by convection, when the heat transfer takes place through displacement of warm water from one site to another of the water body. • This is the prevailing course of heat transfer in fluids. • Solar radiation warms up the upper water layers and the heat transfer in deep layers mainly depends on convection and on the wind. • The heat transfer in the lake determines its temperature at any season as a result of the lake heat balance, i.e. the difference between the input and loss of heat.
  • 77. • In the temperate zone, a hypothetical lake 20 meters deep will progressively lose heat during winter, reaching by the end of the season a temperature close to 4° C at any depth. • The wind activity can easily mix surface and bottom waters that have now the same density. • The spring circulation thus established transfers the surface water, in contact with the atmosphere and thus well oxygenated, towards the lake bottom, charging of oxygen the whole water column
  • 78. Figure. Temperature profile and section of a lake during the circulation, in spring and autumn, and stratification, in summer and winter.
  • 79. Light In Lakes • Perhaps the most fundamental set of properties of lakes relates to the interactions of light, temperature and wind mixing. • The absorption and attenuation of light by the water column are major factors controlling temperature and potential photosynthesis. • Photosynthesis provides the food that supports much of the food web. It also provides much of the dissolved oxygen in the water.
  • 80. • Solar radiation is the major source of heat to the water column and is a major factor determining wind patterns in the lake basin and water movements. • Light intensity at the lake surface varies seasonally and with cloud cover and decreases with depth down the water column. • The deeper into the water column that light can penetrate, the deeper photosynthesis can occur. • Photosynthetic organisms include phytoplankton, algae attached to surfaces (periphyton), and macrophytes.
  • 81. • The rate at which light decreases with depth depends upon the amount of light-absorbing dissolved substances (mostly organic carbon compounds washed in from decomposing vegetation in the watershed) and the amount of absorption and scattering caused by suspended materials (soil particles from the watershed, algae and detritus). • The percentage of the surface light absorbed or scattered in a 1 meter long vertical column of water, is called the vertical extinction coefficient.
  • 82. TEMPERATURE • Temperature is defined as the degree of hotness or coldness. It affects other parameters: It affect states of water (solid, liquid and gas). Water has large capacity to hold heat, specific heat capacity of water equal to unity (i.e. one). Water temp increase, density decreases until 4oC, any further increase in temperature make density remain constant. it also affect dissolved gas, at high temperature low gas dissolved amount of soluble salt in water increases as temp increases. Affect biology of aquatic organisms.
  • 83. TURBIDITY • Turbidity can be defined as the amount of suspended solids in water. • In turbid water, the soil absorbs/ reflects light rays reducing the amount available for primary production. • At optimum light intensity, higher photosynthesis thus dissolved oxygen released into the atmosphere and carbon dioxide is removed. • At higher light penetration more nutrients NO3-, PO4-, etc are utilized thus pH becomes greater as all the acidic CO2 are used up.
  • 84. AMOUNT OF SUSPENDED SOLIDS IN WATER (TSS) • When light penetrated water, any suspended solid absorb/reflect light rays reducing amount of light going beyond them. • Thus, the more dissolved solid, the more turbid water and the less light penetrate it. • To use this we filter to remove all suspended solids (both living and non living, organic and inorganic) using a very fine filter paper with micropore or milipore (40nm) called micropore membrane filter paper.
  • 85. WATER COLOUR • True water colour caused by amount of substance in solution/ colloidal suspension in it and colour result from unabsorbed light ray. • Remember from the incident light. WATER DEPTH • Depth shows relative distance between the beds of water to the overlain shallow water. • It is related to light penetration, thermal stratification, volume and photosynthesis and distribution of organism in the water body.
  • 86. • It is difficult to define "shallow" or "deeper“ of a water body because in some purpose 100m is shallow while 30m is deep in some other areas. The actual variables are: • 1) The extent to which benthos is illuminated by light. • 2) The degree at which benthos is separated from the surface water. • In shallow water, wind and current induce mixing and efficiency of energy transfer and nutrient cycling is therefore enhanced in shallow water, benthos can feed directly on planktons.
  • 87. • Critical depth is the point in water which photosynthesis is the same as respiration. • The shallower the water, the greater the diurnal swing in temperature and because a large proportion of the whole water is within the reach of light radiation.
  • 89. BIOTIC ELEMENTS OF AQUATIC ECOSYSTEMS
  • 90. • In summary, life forms belong to both plant and Animal kingdoms. Can be schemed as: 1. PLANTS • Phytoplankton • Bryophytes • Bryophytes
  • 91. 2. ANIMALS • Zooplankton • Coelterates e.g. Hydra • Annelida (but no polychaetes, Nereis occur) • Arachnid • Mollusks and Insect
  • 92. The small front legs help to gather food and bring it to the mouth. The front legs are short and hard to see if you are looking down on this insect, unlike the front legs of our next guest! WATER BOATMAN These insects scavenge dead plant and animal material found and along the bottom of the wetland.
  • 93. BACKSWIMMER These predators lie on their backs just under the water surface and use their long front legs to grab insects that land on the water. The front legs of the backswimmer are much more visible than those of the water boatman, allowing easier identification when both are viewed from the top.
  • 94. PREDACEOUS DIVING BEETLE Diving beetles are predatory insects that breathe using tubes that come out of their rear-ends! Air is obtained from the surface and stored in a space underneath their hard wing-covers created by thousands of very tiny hairs. Adult Larva Just like butterflies, these beetles have complete metamorphosis. Eggs are laid close to the surface on plants and larvae that are ferocious predators hatch and eat things like mosquito larvae under the water.
  • 95. DRAGONFLY NYMPH Dragonflies have incomplete metamorphosis. Young dragonflies live in the water and are called nymphs. They will shed their skins many times until they finally come out of the water to become adults. Dragonflies are great predators, and have a mouthpart called a labium that extends out and grabs their prey with sharp hooks. The type of dragonflies we find in the water here belong to the skimmer or libellulidae family. They look like this and can be found crawling along the muddy bottom of wetlands all over Ontario. This is good because both dragonfly nymphs and adults hunt insects like mosquitoes!
  • 96. DRAGONFLY ADULTS The adult dragonflies we see most often here are the Common Whitetail and the Twelve-spot Skimmer. Both of the pictures represent male dragonflies. The females of both of these dragonflies have duller colouration. Common Whitetail Twelve-spot Skimmer
  • 97. MAYFLY NYMPH If mayfly nymphs are present in the aquatic ecosystem it indicates that the health of the ecosystem is good. Mayfly nymphs require clean water that is well oxygenated, and excess nutrient levels cannot be tolerated. Mayflies will soon disappear from ecosystems that are negatively affected by human activity. Scientists find these types of organisms to be good indicator species of Nymph Adult
  • 98. AMPHIBIAN GROWTH AND ECOSYSTEM HEALTH Tadpoles develop from eggs laid in the Spring. Most of the dots you see in this egg cluster will become tadpoles in a healthy ecosystem. Tadpoles, like other amphibians, are sensitive to changes in water quality. Some species remain in this vulnerable stage for 2 or 3 years. When a tadpole’s legs appear it is called a froglet. Occasionally froglets are found with mutations caused by contaminants. If the contamination is sufficient, adult frogs will not be observed or will be less numerous, since the egg, tadpole or froglet stage has been harmed by pollutants or toxins.
  • 99. PAINTED TURTLE Painted turtles basking in the sun. Turtles are not as sensitive as frogs are to changes in abiotic factors that cause negative ecological impacts. This is due to the fact that reptile skin doesn’t allow water to enter it as does amphibian skin. Therefore amphibians are better indicators of chemical changes affecting aquatic ecosystem health.
  • 100. OUR MARSH BIRDS Red-Winged Blackbird Mallard Duck Ducks rely on native plants and organisms as well. Ducks act to recycle nutrients, spread seeds, control insects, and provide food for many species. Invasive species and pollution affect our ducks as well however, and some duck species are decreasing in number as a result. Great Blue Heron Since the great blue heron is a predator, it accumulates many of the toxins present in the environment. Because it preys mainly on aquatic organisms, its fatty tissues can tell us what contaminants may be a problem in our aquatic ecosystem. These birds need native wetland plants to build their nests and wetland insects to feed their young. Unfortunately, invasive plant species are taking over our wetlands, harming many native species.
  • 101. • Note that protochordates and echinoderms do not occur in FW. Cirripedia in crustacean class does not occur in FW. However, other many vertebrates e.g. fish, amphibians, reptiles (snakes) and birds which depend on water and mammals do occur in FW. • It has been noted that many fauna and floral varieties occur more in marine than in FW. • These aquatic organisms are divided into different groups based on their micro-habitats. These include:
  • 102. • (a) Neustron – organisms resting on water surfaces e.g. Gerris • (b) Plankton – Live suspended in the water. Sometimes called drifters or floaters because they cannot control their movement but influenced by water current e.g. the phytoplankton (plant-origin) and zooplankton (animal-origin). Each member of plankton is called plankter. • (c) Nekton – organism which can control their movement and swim in the water. They are macro- organisms e.g Crustaceans, molluscs, fishes.
  • 103. • Plankton and Nekton are grouped together as pelagic or limnetic organisms because they live within the water column i.e. below the surface of water and above the bottom. • (d) Benthos – organisms which live in or on the bottom of the water. • Apart from all these, some organisms live attached to plants e.g. Hydra. This is called periphyton. Some are attached to rocks inside the water called Aufwuch.
  • 104. Phytoplankton are divided into 5 groups as: • i. Diatomaceae • ii. Myxophyceae • iii. Dinophyceae • iv. Euglenoceae • v. Chlorophyceae
  • 105. Zooplankton are divided into • i. Rotifera • ii. Cladocera • iii. Copepoda • iv. Coelenterata • v. Protozoa
  • 106. Features of biological success of planktonic organisms • i. Members have very high surface area to volume ratio. This leads to an increase in frictional force which decreases the rate of sinking of the organism. • ii. Cyclomorphosis is a process whereby planktonic organisms exhibit changes in length of their appendages (spines) with the density of water e.g..
  • 107. • Ceratium shortens its spine during winter when density is high as it needs less energy to keep afloat. afloat. During summer when density is low, Ceratium
  • 108. • v. Planktonic organisms exhibit patchiness whereby they are not evenly distributed to reduce pressure from predators. • vi. Plankton shows seasonality in abundance. This depends on change in water current, water level, transparency and amount of nutrients available i.e. conductivity. • vii. Most of the animal plankton are transparent which provide protection from the predators. • viii. Planktonic organisms show diurnal ventral migration.
  • 109. • Nekton – are fishes and crustaceans mainly. So also molluscs. • Benthos – Occur at the bottom of water, include bacteria and fungi, protozoan, leeches, oligochaetes, planarians, ostracods, crabs and prawns, coleopterans. They are many snails. • Periphyton include Hydra which attach to plants, water mites and rotifers. • Neustron – stay at surface of the water. These are mainly arthropods – Gyrinus, Gerris (Pond skater), adult mosquito (temporarily).
  • 110. PLANTS • a. Floating plants – float freely on water e.g. Pistia, Lemna Salvinia • b. Submerged Vegetation – Plants completely under water e.g. Ceratophyllu, Utricularia • c. Rooted vegetation – Have roots at the bottom but leaves appear on the surface of water e.g. grasses and sedges
  • 111. YELLOW POND OR BULLHEAD LILY Leaves float on the surface of the water, absorbing sunlight and shading the water. This reduces warming and algal growth. The leaves also provide great cover for wetland organisms!
  • 112. MARSH PLANTS ARE AMAZING! Plants like cattail prevent flooding by acting like sponges to store excess water. Cattail also let water out of their tissues during droughts when the water levels are low. Marsh plants hold the soil in place to prevent erosion. Marsh plants act as filters to soak up and store lots of the chemicals we dump into the water. Native wetland plants also provide habitat for huge numbers of wildlife!
  • 113. UNDERWATER VEGETATION Many plants inhabit the subsurface waters of aquatic ecosystems. Elodea is one example of an underwater plant that produces large amounts of dissolved oxygen for aquatic life forms. This plant acts to clean the water and remove large amounts of carbon dioxide. Submerged plants also produce food and shelter for many types of wildlife.