Marine ecosystems are distributed on-shore and off-shore. The on-shore ecosystems are very typical ecosystems subjected to the everlasting action of oceanic waves and tides. The life of on-shore ecosystems are always under the dynamic impact of various factors including human interventions.

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ON-SHORE ECOSYSTEMS
By
Prof. A. Balasubramanian,
Centre for Advanced Studies in Earth Science,
University of Mysore,
Mysore-6

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Introduction:
Marine ecosystems are distributed on-shore and
off-shore.
The on-shore ecosystems are very typical
ecosystems subjected to the everlasting action of
oceanic waves and tides.
The life of on-shore ecosystems are always under
the dynamic impact of various factors including
human interventions.
Many animal groups thrive on the sandy beaches
and most of them are very small and even less
than 1 millimeter.

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More or less all sand beaches have certain
common characteristics.
All are composed of bottom material that has been
affected and worn by wave action.
The waves constantly change the appearance of
the beaches are fragile ecosystems which need
much attention and in depth study.
In this episode we are going to see the on-shore
ecosystems.

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The following are the modules covered in this
session.
1. Fore-shore ecosystems
2. Sandy foreshores or beaches
3. Shingle or muddy foreshores.
4. Salt marshes and rocky foreshores
5. Environmental concerns of on-shore
ecosystem

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1. FORE-SHORE ECOSYSTEMS
The shoreline is a unique boundary linking the
earth’s environmental domains like atmosphere,
hydrosphere, lithosphere and biosphere. It is one
of the man’s oldest frontiers and most informative
paleo-oceanographical tablets. Though the
continental shelves and near shore waters
comprise only about 5 % of the area of the globe,
about two thirds of the world’s population live
near the coast.

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Foreshores are the land bordering the seas and
oceans.
The geomorphologies of foreshores vary from
place to place and based on the slope of
continental margins.
These are at the forefront of the continents facing
the action of waves and tides directly.
They are the zones of land-sea interactions.

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The abiotic factors controlling the fauna and flora
are:
1. Geomorphic factors-width, length, slope,
thickness and geology of coastline
2. Hydrographic factors-water and its salinity
3. Light
4. Temperature, air, wing and humidity
5. Tides, waves and mean sea level

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The notable fore-shore ecosystems are
a)Sandy foreshore
b)Shingle foreshores
c)Lagoons
d)Muddy foreshores
e)Salt-marshes and
f) Rocky foreshores
Foreshores are aesthetically pleasing
environments.
They are called as on-shore ecosystems.

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The following are the problems of shore life.
1. Water loss: Inhabitants of sea-shore are mostly
aquatic. When they are left uncovered by
water, they die from dehydration.
2. Wave action: This has a destructive impact
over life forms. It creates difficulties for
settlement and attachment.
3. Temperature and its fluctuation: It is due to
high or low tides, sunshine, shallow pools;
severe frosts, etc.

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4. Fluctuations in salinity, oxygen, carbon-di-
oxide and pH levels.
5. Light penetration and illumination.
6. Predation, immersion and pollution.
The following are the characteristic features of the
shore life.
1. Littoral forms shelter under rock pools,
boulders and crevices.
2. Shore animals have a flattened shape for
hiding in narrow spaces.

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3. Organisms, subjected to the dehydration
problems (due to their exposure to air) have
protective covers which may be. (Thick
cuticle).
4. Surface-dwelling animals have strong shells
with orifices.
5. Shore animals lose waters by excretion. They
excrete ammonia as their chief mitrogenous
waste product. This is toxic and has to be
eliminated by dilution.

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6. Shore dwelling animals perform aquatic
respiration, in the littoral fringe and aerial
respiration on exposure to air.
7. Benthic organisms start their life as floating or
swimming forms shore creatures have the risk
of losing pelagic eggs and larvae stages due to
drifting currents. Some eliminate the pelagic
stage and emerge to an adult form.
8. Physiological and behavioural adaptations are
properly done by these organisms, even to
withstand the twelve hour tidal cycles.

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9. A zonation exists in the population of plants
and animals in the fore shore in these costal
ecosystems.
Some of the creatures that use tixotropi when they
dig are worms, gastropods and mussels.
They flush water onto the sand and make many
small penetrating movements whilst they push
down into the sediment.

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Those organisms and creatures that are most
noticeable when one visits the beach are those
most importance the vegetation in sand dunes,
birds, mammals and insects and also the remains
of the organisms that have been washed up and
left on the beach.
The notable ones are seaweed, shellfish, mussels
and jellyfish.
Many of the permanent inhabitants are not noticed
directly, because they are either dug down into the
sediment or are very small.

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2. SANDY FORESHORE
A beach is the land bordering the sea and is
defined as an accumulation of sediment laid by
the waves and tides.
It usually consists of sand or gravel. Beaches are
fragile ribbons of sand that are frequently broken
by action of nature and man.
Shore processes begin thye mixing, sorting and
transportation of sediments and of runoff from
land.

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Waves, winds and currents mold the shorelines of
the world.
Beaches are composed of whatever classic
material is locally available in great abundance.
An active beach, the area of loose sediment
subject to transport by wind, waves, and currents,
is divided into three regions:
The backshore,
The foreshore and
The offshore.

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A beach is characterized by a coastal upland,
which can be a dune, a cliff, a soil embankment, a
fossil berm, or an ecosystem structure such as a
seawall or a revetment.
The gemorphic features of the beach include
berms, scarps, on-shore and offshore sand bars.
These are dynamic ecosystems with sedimentary
basements. The sediments may contain shells of
recent to sub-recent life, Fossils, skeletal remains
from coral reefs, Sand / silt transported by waves
and materials from the River input.

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A beach is formed on a gentle slope of a coast due
to the action of waves and tides which have
created, supplied and deposited the sediments. If it
is made of dominantly sand size particles then it is
termed as a sandy beach or foreshore.
The term sandy is applied to grains with diameter
ranging from 0.05 to 2.0 mm. Sandy features are
flatter than others. The nature of sands on any
beach depends on the type of rocks present or
below.

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Sands are admixed withy the shells, plates and
shells, and spines of organisms living on
foreshores.
The main constituent of these sands may be quartz
or silica. A sandy beach will never be static but
always be a dynamic ecosystem.
The major factor is wave action. Large algae or
rooted vegetation cannot thrive on shores due to
the lack of stable solid surface.
The life forms of this area are diatoms,
dinoflagellates and flagellates.

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The micro fauna includes nematodes, copepods
and coelenterates. The burrowing macro fauna
includes bivalve mollusks, polychaetes and
amphipods. In marine waters, one can see starfish
which are immensely strong. They eat shellfish,
such as oysters.
Ecological features
1. Each tide brings fresh food to the system.
2. The ecosystems contain permeable sand which
acts as a high energy window, concentrating
organic matter in the beach
3. Tides provide the supply of oxygen

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4. Basic producers are the algae and diatoms of
the littoral zone. Others are consumers.
Predators are the seabirds and ones organisms.
In sands mostly lichens, herbs and bushes grow.
Sand is a very poor source of nourishment, but
seaweed and other organisms that are washed up
into the beach can supply a certain amount of
nourishment. Certain specie are totally dependent
on this source, and survive only on or banks of
washed up seaweed.

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Vegetation that grows amongst the dunes and
these banks of seaweed must tolerate high salt
concentrations, most terrestrial plants do not.
Algae can be found on submerged rocks as long
as they are not chafed away or covered by sand.
Where the sediment is protected enough from the
waves, soft bottoms are seldom devoid of
vegetation.
There, they can attach themselves to the bottom
without being washed away. Sand beach flora
below the water line consists of small single-
celled algae.

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Diatoms that creep on the grains of sand are so
small that several hundred can be placed on a
single grain of sand. Their movements often
follow variations in the light, creeping down
amongst the grains during the night, and sitting on
top of the sand during the day.
3. SHINGLE AND MUDDY FORESHORES
This is a foreshore environment where in the
sediments are larger in diameter than sand and
have negligible capillary forces.

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The size of grains may be more than 2 mm.
Single size fractions include
Boulders (> 200mm),
Cobbles ~ (60-200mm),
Coarse gravel (20-60 rrfm)
Pebbles (6-20mm) and
Granules (2-6mm).

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Shingle structures in coast include fringing
beaches, spits, bars or barriers, cuspate forelands
or opposition beaches and offshore barrier islands.
The environmental factors responsible in its
formation are adequate supple of material,
waves,winds and tidal currents.
On the basis of the presence or absence of
vegetation, there will be
a “no vegetation” zone,
a zone of summer annual species and lastly
a zone of short-lived perennial species.

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LAGOONS
Lagoons are shallow bodies of brackish or salt
(sea) water partially separated from the
neighboring sea by barriers of sand or shingle.
The sea water can flow only through narrow
openings left by the barriers.
They become the coastal ponds or lakes, if they
are completely detached from the sea.

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The following are characteristic features of this
ecosystem.
1. Found in low-lying coasts.
2. Aligned parallel to the coast line.
3. Orignate by a marine transgression into the
previously existing freshwater lakes, or by the
invasion of land below sea level after storms.
4. Physical conditions are subjected to the short
term and long term fluctuations and also to the
mixing of sea water and freshwater.

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5. Some fauna and flora are permanent in
lagoons.
6. There will be much variations in the
population of species presence lagoons
7. Productivity of the entire ecosystems depends
on the phytoplankton and benthic plants.
Production is consumed after decay-by the
microbial organisms.
8. Water temperature is express to be similar to
mean air temperature.
9. Salinity of water also9 varies with reference to
space and time.

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The flora includes flagellates, certain bacteria and
fungi
MUDDY FORSHORES
These are the feeding grounds for many wading
birds, wildfowl.
Mud is characterized by its fine textures,
deposited under turbulence of sea water. Mud has
an adhesive quality.

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The intertidal invertebrates are dependent on the
organic matter of the mud. The macro-
invertebrates present in such zones are:
a)Burrowing animals-completely concealed
under low water (ragworm, polychaete worms)
b)Animals which are exposed on the mud likely
to go inside-type (gastropods, winkles)
c)Animals thriving on the mud-surface (mostly
animals-Crustaceans. Mollusks and barnacles)
Birds, ducks, geese and brent goose are the others,
thriving over these mud lands.

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Sand dollars are easy to find at low tide. They are
round little sea creatures that live half-buried in
wet sand.
A sand dollar feeds by sucking sand into its body
through little slots or holes. It digests microscopic
organisms that live in the sand.
A living sand dollar is brown or gray and looks
like a furry cookie. The fur is actually made up of
thousands of little spines that it uses to move
about.

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Horseshoe crabs are shaped like a horse’s hoof
and can grow up to 2 feet in length.
They have six pairs of legs and are closely related
to spiders. The creature’s tail is actually a sharp,
jointed spine.
A careless step on a horseshoe spine can take you
on a painful trip back to reality.
If an object looks like a plastic bag full of dirty
water, and it’s lying above the waterline it just
might be a jellyfish.

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Jellyfish thrive in warm water, and can be hard to
see while swimming in our area’s less-than-clear
waters.
The turtles are the reptile of these coastal belts.
4. SALT-MARSHES AND ROCKY
FORESHORES
Marsh is a low lying tract of soft, wet grass land
that provides an important ecosystem for a variety
of plants and animals.

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Salt marshes are the zones lying near to shores
periodically flooded by saltwater. They are also
called as tidal marshes, in which the water level
fluctuates tidally or non-tidally.
Due to the recurring failure of monsoon, salt
marshes extend further land wards.
The soil includes heavy to sandy clay, silty sand
or silty peat.
Lives in this area are subjected to tidal changes
and salinity variations. The herbivores feed on
standing marsh plants and transform energy
seasonally.

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Micro-organisms (animals) feed on algae and
plant detritus.
The producers are phanerogams and algae.
The consumers include mammals, parasitic fungi,
bacteria, birds, arthropods and mollusks. The
predators are the birds and arthropods.
Birds and human are the top predators
(carnivores) in tidal marshes. Plants are
submerged in water and exposed to sun due to the
tidal cycle.

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The zonations of life in tidal marshes involve
algae-eelgrass-seapoa-saltwater cord grass-
marshy-hay cord grass-black grass-tussock
forming grasses.
The last unit is followed by the coastland normal
vegetation.
ROCKY FORESHORES
This is quite opposite to that of a sandy shore, in
which the substratum is a hard base. The shore
zone is the sedimentary and solid surface
associated directly with the interaction of waves
and wave induced currents on the land.

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Topographically they are platform like, cliffs and
islets.
The surface may be smooth or rugged animal life
is rich on these shores. Algae and phytoplankton
are the producers.
Limpets, fleas and snails are the consumers
feeding on algae. The prevailing physical factors
are high temperature, light intensity, salinity
changes, evaporation of water,
Dilution due to rain, etc

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Shore forms have a sedentary mode of life, as
they attach to the rocks.
They are also capable of tolerating the wave
stress. Fishes, gastropods, and crustaceans live in
the rock cracks. Boring mollusks, craps and
echinoderms are also common.
The organisms have the characteristic feature of
thermal adaptations. The lives in rocky shore are
subjected to varying conditions and the zonation
in life includes;
a) Supra littoral zone-lichens, algae, etc

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b) Littoral zone-(covered and uncovered by
tides) barnacles, sea weeds, red algae,
oyster, blue mussel, etc.
c) Infra-littoral zone-open sea-nerritic and
benthic life.
5. ENVIRONMENTAL CONCERNS
Coastal ecosystems are subjected to various
natural and man-made influences.

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Human dependence on the reefs for food,
materials and income (tourism and export), had
led to increases in the level of unsustainable
exploitation (over-fishing) of the coastal
resources.
As the waves approach the shore and pass into the
shallow waters, several changes of great
importance occur.
Coastlines are subjected to the influence of the
following:
a)Erosion – by sea waves.

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b)Accretion- organisms (plants) promote
accretion
c)Longshore movement of materials from one
place to other.
d)Human activities-construction of Barrages,
airports, fences, ditches, ete, and discharge of
pollutants.
Urbanization, commercial and subsistence
activities are putting increasing pressure on
coastal resources.

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Most stocks of commercial invertebrates
including green snails and pearls are over
harvested
Turtles are hunted despite a ban on harvesting
of turtles
Mangrove forests are destroyed by
overexploitation
Mollusks, sponges, sea urchins, giant clams,
crayfish and sharks are some of the other many
marine animals harvested for various reasons.

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Soil erosion and mining of heavy minerals like
garnet sands lead to huge discharge plumes of
sediment into lagoons, destroying critical marine
habitats.
Urbanization is a major threat to marine
ecosystems causing extensive eutrophication in
near shore areas.
Most of the municipal sewage is sent directly into
marine near shore waters.

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The sewage contaminants enhance the growth of
algae, which may form a dense covering over near
shore areas causing suffocation or underlying
sediments and inhabiting organisms.
Some of the untreated human sewage contains
enteric bacteria, pathogens and viruses, and eggs
of intestinal parasites which can be extremely
hazardous to the communities using the near shore
marine environments.

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The major pressures of these ecosystems are:
Storms;
Disruption of sand transport
Pollution;
Trampling;
Recreation/tourism;
Litter;
Beach cleaning;
Mining;
Groundwater over exploitation

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Collection of invertebrates for different reasons
and also collection of materials for food bait and
food; and
Fishing
The mostly recommended management measures
are
Restricted beach access;
Elimination of off-road vehicles;
Strict control of exploitation of beach animals for
food or bait; and special attention to the need for
protection of threatened and endangered species
such as sea turtles and some seabirds.

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Over the long term, beach nourishment should be
encouraged as a counter to erosion. Beach
regulations prohibit any visitor from harming,
bothering, or removing any sea life from such
places.
The fish, birds, crabs, starfish, sand dollars, and
sea turtles are all part of a complex system that
should be enjoyed, but not disturbed.
Let us protect these ecosystems which are fragile
and vulnerable to our intervention.