B.Sc First year Syllabus

1. Marine
Ecosystem
DR. ASMITA DASPUTE.
ASSISTANT PROFESSOR.
SBES COLLEGE OF SCIENCE, AURANGABAD. (MS)

3. Introduction
 Aquatic Ecosystems are classified into two types as freshwater ecosystems and marine ecosystems. The
habitats of the open seas and adjacent coastal zones are classified under marine ecosystems. In addition to
these, marine ecosystems also include the salt marshes and wetlands located along the shores and river
mouths. Within the coastal zone, several unique habitats like estuaries, tidal inlets, and foreshore ecosystems
are also included. Such zones including estuaries contain the habitat of both freshwater and salt water. The
subject of Physical geography includes the study of all these ecosystems.
 The following aspects are to be studied under marine ecosystems:
 1. Characteristics of Marine Ecosystems
 2. Oceans
 3. Estuaries
 4. On-shore ecosystems.
 5. Coral reefs.

4. 1. CHARACTERISTICS OF MARINE ECOSYSTEMS
 Marine ecosystem is characterized by the many biotic and abiotic
components.
 Biotic components are:
 Organisms and their species
 Predators, Parasites, Competitors and
 Mates.

5. The Abiotic Components (Physical and Chemical) are:
 Temperature , Concentration of Nutrients
 Sunlight, Turbulence, Salinity and density.
 The following are the properties affecting the life in the seas and oceans:
 1. Quality of sea water
 2. Skeleton shape and size of organisms
 3. Buoyancy
 4. Gravity
 5. Temperature
 6. Density of water
 7. Light penetration in water
 8. Availability of Nutrients
 9. Water turbulence and
 10. Hydrostatic pressure of water

6. Fa
 Marine environments have altogether different kinds of Physical conditions for life to survive.
 Majority of marine plants are floating species and microscopic.
 Many marine animals are invertebrates. They do not have massive skeletons.
 For floating and swimming, marine life require little energy. Water which is a fundamental constituent of
all living organisms, is available in plenty within these marine environments. Temperature is yet another
parameter which do not vary as drastically as seen on land or in the air. However, there are certain
properties which are less favourable for life in the seas and oceans. Plant growth in the sea is limited by
light.
 It is a fact that 50% of the total solar radiation which penetrates into the sea surface, gets disappeared
rapidly within a few meters of depth.
 Much of the marine environment is in perpetual darkness. Under such circumstances, many of the marine
life depends on the availability of essential nutrients only.
 It is also to be noted that the zone just below the sea surface, experiences the maximum environmental
fluctuation.
 This is the zone where there is more air-water interactions, much variations in temperature, salinity and
turbulence of water. Winds plays a major role on the surface of the sea.

7. 2. OCEANS
 The World Oceans are the huge volumes of sea water belonging to the
hydrosphere.
 Oceans cover more than 70 per cent of the earth's surface. About 97 per cent of
all the water available on the earth are in the oceans.
 Oceans contain both valuable and much needed natural resources.
 They are the sources of food, energy, and minerals.
 Oceans also serve as waterways for ships to transport people and carry cargo
between continents. The primary role of oceans and seas lie in maintaining the
global climate by regulating the air temperature and by supplying the moisture
for rainfall. Without oceans, life would not have originated in our planet.
 When compared to land based terrestrial ecosystems, the marine ecosystems have
certain unique features.

8. OCEANS
 1. the oceanic environment is very wide, covering 75% of the earth’s surface.
 2. The oceanic systems are very deep in which life extends to all depths.
 3. The water masses of sea and oceans are continuous.
 4. The water is in continuous movement in both vertical and horizontal dimensions.
 5. The water is salty with an average salt content of 35 g/litre.
 6. The concentration of dissolved nutrients is low.
 Creatures living on land need to deal with gravity, dehydration, great temperature
variations, and many other factors which are normally not encountered in oceans.

9.  The distribution of marine life includes the study of planktons, Phytoplanktons,
 Zooplanktons, Nektons and the Benthos.
 The Temperature fluctuation is minimum in oceanic waters.
 Arctic waters are colder.
 Tropical waters are warmer.
 The variation is seasonal and diurnal.
 Ocean animals show a varied response to the temperatures.

10. Zonation of Ocean

13. There are two kinds of animals.
 1. Stenothermal animals – the ones which live within 20°C
 2. Eurythermal animals – the animals which can withstand the wide range of temperature variations.

14. OCEANS
 The cold water forms also show an increase their in sizes.
 The surface temperature of the oceanic waters vary from about -2 °C near the North and South poles to
about 30 °C near the equator.
 In the polar regions, the surface sea water freezes. The western tropical Pacific has the warmest surface
water. Ocean currents affect the surface temperature.
 Ocean temperature also varies with depth. In general, the temperature falls as the depth increases.
 Light is very essential for the marine life. For photosynthesis, heating, radiations and vision are related
to this factor.
 It determines the plant and animal life and depends on the angle of incidence.
 Perpendicular rays go deeper into the oceans.

15. Based on the intensity of light the water body of marine
ecosystems can be differentiated into three zones.
 Euphotic zone -extends upto 100 m depth, illuminated zone production zone , rich
with phytoplankton, primary consumers and secondary consumers.
 Disphotic zone - lies between 100 and 200 m depth, weakly lighted, secondary
consumers live with a few primary consumers, Rare plant life.
 Aphotic zone - above 200m depth , No light, no producers, no photosynthesis,
secondary consumers, feed on other animals also.
 Euphotic Zone is the uppermost layer of the world's oceans.

18. FOOD WEB

20. ESTUARY ECOSYSTEM

21. ESTUARIES
 Estuaries are the coastal areas where the saline waters of the ocean meet with the fresh water of the rivers.
 Estuarine habitats are usually very productive because of the accumulation of nutrients from a large
catchment of a river.
 Estuaries offer good fishing grounds as the water column is shallow and easily approachable.
 These are the breeding habitat for a variety of Shrimp and Prawn species, oysters and fishes.
 Estuarine waters are therefore salty or brackish in quality.
 They are complex ecosystem comprising of three zones as,
 1. polyhaline zone(low salt),
 2. mesohaline zone (medium salt) and
 3. oligohaline zone(fully saline).

22. ESTUARIES
 Ecologically, an estuary is an area of dynamic biogeochemical activity.
 Estuaries are critical for the survival of many species of birds, mammals, fish
and other wildlife.
 Rivers and streams drain into the estuaries. They bring-in enormous amounts of
nutrients from uplands
 Estuaries may be small or large depending upon their dimension, size, shape
and the quantity of river staying inside and flowing inside.
 Estuary is also considered as a Maritime Nursery. It is a place where young
fishes and a few other organisms are protected from predators and competitors
which may not be able to enter into the low salinity waters.

24. The Biota of Estuaries are classified as
 a) Producers
 b) Zooplanktons
 c) Benthic invertebrates
 d) Fishes
 e) Birds and wildlife.
 1. The Producers include
 Phytoplankton - diatoms, dinoflagellates, green algae.
 Macroalgae - red algae, green algae, brown algae.
 Microalgae - benthic diatoms.

25. Zooplankton -
 Zooplankton - grazing herbivores & carnivores. They include Copepods, larval fish, fish eggs,
chaetognaths.
 Larval invertebrates - oysters, clams, corals, etc.
 jellyfish (small & large)
 ctenophores - very abundant in plankton of estuaries.
 The benthic invertebrates include:
 clams, oysters, mussels, snails (mollusks)
 polychaete worms
 amphipods
 decapods - crabs, shrimp, lobsters

26. Zooplankton -
 The Fishes include the migratory fish which enter via the inlet are anadromous fish, striped
bass and salmon, spotted seatrout, and red drum.
 Estuaries are important feeding areas for many migrating birds. The estuarine shores show
plovers, skimmers, gulls, oyster catchers, terns, pelicans, ducks, and ospreys.
 Reptiles include sea turtles, which consume fish, inverts, and seagrasses.
 Mammals include otters, raccoons, nutria, dolphins and sometimes whales

27. Food Chain

28. Food Web

29. Thank you