PresentationPDF Available

Aquatic Ecosystems-Marine Types

Authors:

Abstract

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.
1
AQUATIC ECOSYSTEMS-MARINE TYPES
BY
PROF.A.BALASUBRAMANIAN
UNIVERSITY OF MYSORE
18-10-2011
Introduction:
Life on earth is supported by the surrounding ecological conditions and the natural resources.
Continents and oceans are the two major divisions, comprising of all the life and also the ecosystems
throughout the world. About 75 % of the earth’ surface is covered with oceanic waters which has a very
rich wealth of marine life. The ocean is a major source of food, energy, and mineral resources. Oceans
also control the global climate. If we say that land is dominated by plant biomass, then we have to say
that animal biomass dominates the oceanic waters. Water-based living environments are called as
aquatic ecosystems.
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.
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.
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 of water
2
6. Density of water
7. Light penetration in water
8. Availability of Nutrients
9. Water turbulence and
10. Hydrostatic pressure.
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.
All environmental parameters show predominant vertical gradients.
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.
They are:
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.
3
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.
The Divisions of Marine environment included in the study of open sea are:
a) pelagic environment,
b) epipelagic environment,
c) mesopelagic zone,
d) bathypelagic zone,
e) abyssopelagic zone, and
f) benthic environment- sea bottom.
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.
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.
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.
Based on the intensity of light the water body of marine ecosystems can be differentiated into three zones.
They are
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.
4
Marine Ecology involves the understanding of all these aspects.
3. 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.
They also provide sheltered harbours for ships and their traffic. Estuarine waters are used for cooling of
water in power generation plants.
An estuary is a semi-enclosed coastal body of water that has a free connection with the open sea at one
side and a river on the other side.
The circulation of water in any estuary depends on the amount of freshwater outflow, the strength of the
tidal current and the amount of vertical mixing.
Estuarine waters are therefore salty or brackish in quality. Structurally, they are deep funnel shaped
mouths. They are complex ecosystem comprising of three zones as, polyhaline zone(low salt),
mesohaline zone (medium salt) and oligohaline zone(fully saline).
The marine side is called as lower estuary. It has a free connection to the sea with salinities exactly equal
to that of the oceanic waters. It is called as Polyhaline zone. The total dissolved salts of this zone may
range from 30 to 35 ppt.
The middle estuary which is subject to mixing of salt and freshwater is called as the mesohaline zone. The
salinities of this zone may be around 15 ppt in the waters.
The upper or fluvial estuary which is characterized by the flow of freshwater is known as oligohaline
zone. The level of salinity in such zone may be around 0 to 5 ppt.
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.
Plants use these nutrients, along with the sun's radiant energy, carbon dioxide and water to manufacture
food. As long as the nutrient-rich freshwater flows towards the estuaries , the estuaries will remain
productive.
Estuaries may be small or large depending upon their dimension, size, shape and the quantity of river
staying inside and flowing inside.
The sediments carried by the streams are also dropped into the quiet water mass of estuaries. Continuous
sedimentation may shorten the dimension of estuaries especially in the upper reaches.
5
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.
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.
SAV seagrasses are common in estuaries.
The emergent plants include Spartina, Juncus, Batis, Sallornia.
2. 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
The Fishes include the migratory fish which enter via the inlet are anadromous fish, striped bass and
salmon, spotted seatrout, and red drum.
Juvenile fishes predominate in estuaries at nursery level.
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.
4. ON-SHORE ECOSYSTEMS
Marine Ecosystems are distributed as on-sore and off-shore ecosystems. The on-shore ecosystems are
very typical ecosystems subjected to the everlasting action of waves and tidal influences.
6
The life of on-shore ecosystems are always under the dynamic impact of various factors including human
interventions. They are called as Foreshores.
Foreshores are the lands bordering the seas and oceans. The geomorphology of foreshores may vary from
place to place and based on the slope of continental margins. Foreshores are at the forefronts of the
continents, facing the action of waves and tides directly. They are the zones of land-sea interactions.
The abiotic factors controlling the fauna and flora of foreshores are:
1. Geomorphic factors- Width, length, Slope, thickness and Geology of the coastline.
2. Hydrographic factors- Water and its salinity.
3. Light
4. Temperature, Air, Wind and humidity.
5. Tides, Waves and mean sea level.
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.
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.
3. Organisms, subjected to the dehydration problems (due to their exposure to air) have protective
covers.(thick cuticle).
4. Surface-dwelling animals have strong shells with orifices.
5. Shore animals lose waters by excretion. They excrete ammonia as their chief nitrogenous waste
product. This is toxic and has to be eliminated by dilution.
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.
9. A zonation exists in the population of plants and animals.
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.
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.
7
A beach is characterised by a coastal upland, which can be a dune, a cliff, a soil embankment, a fossil
berm, or an engineering structure such as a seawall or a revetment. The geomorphic features of the beach
include berms, scarps, and offshore sand bars. Beaches are dynamic ecosystems.
Beach sediments may contain shells of recent to subrecent life fossils, skeletal remains from coral reefs,
sand / silt transported by waves and materials from the river input.
A sand beach will never be static but always be a dynamic ecosystem. The major factor is wave action.
Large algae or rooted vegetation can not thrive on shores due to the lack of stable solid surface.
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.
Muddy foreshores are the coastal mud-lands or mudflats, containing mostly mud organisms.
They are the feeding grounds for many wading birds, wildfowl. Mud is characterized by its fine texture,
deposited under turbulence of sea water. Mud has an adhesive quality.
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.
Life in this areas are subjected to tidal changes and salinity variations. The herbivores feed on standing
marsh plants and transform energy seasonally.
5. CORAL REEFS
Coral reefs are major geological structures built by biological activity.
`Corals' can be seen along some of the beaches, looking as a piece of rock-like material. The corals are
the skeletons of many tiny sea animals living side by side. Each one of these animals is known as a coral "
polyp".
A coral polyp is a soft, almost transparent animal which builds its own skeleton outside its body. Since it
has no backbone, it is an invertebrate.
Corals which produce a hard skeleton are called stony corals.
They have special cells on the outskirts of their bodies which produce a limestone substance. This makes
them hard, like a rock .The polyps sit in the cup like portions of the skeletons.
Corals belong to a large group of invertebrates which includes jelly fish, sea anemones and hydroids.
The types of corals are
A . STONY CORALS :
1. Stony corals
8
2. Finger corals
3. Fungus coral
4. Brain coral
5. Tube coral
6. Rose coral
7. Staghorn coral
8. Lettuce-leaf coral
B. SOFT CORALS :
1. Sea fan
2. Bushy soft coral
3. Sea feather
4. Black coral.
The live hard corals can be divided into four major forms:
a. Branching
b. massive
c. Tabulate / flat
d. Others.
The coral growth needs a clean and warm waters. The best temperature for coral growth is 18°C.
In general, reefs form where the following set of conditions are met:
Warm water, not cooling below 18°C during the year.
Wave-swept, high energy coast.
Hard substrate.
Normal marine salinity water.
Absence of abundant clastic detritus.
Shallow water (0 - 30 meters depth - photic zone)
The ecosystem characteristics are varied from that of the others.
1. Corals reefs are made up of much more than corals and their skeletal remains. The other organisms
living in reefs, deposit calcium carbonate (limestone) materials.
2. Reefs provide the home, (food and shelter) for a wider variety of plants and animals. The spaces, sinks
and cracks in the hard coral mass, make suitable shelter and feeding grounds for the marine worms,
urchins, sponges, sea fans, molluscs, crabs, shrimps, sea anemones and fish.
3. The energy which cycles through the reef, keeps all plants and animals alive: The energy comes from
the sun.
The reef environment supports the planktons. Plants are abundant: in reefs. They provide the basic food
for the entire ecosystems.
There are many reef animals which eat the plants and are eaten by other animals. They are small, like
crustaceans and worms.
There are many larger animals like sponges. There are zooplanktons living at the base.
Coral reefs can be classified based on their Morphology, evolution, size, depth of surrounding water, and
relationship to nearby land. Morphology is the major criteria considered.
9
The major types of coral reefs are as follows
1. Shore Reefs - or - Fringing Reefs
2. Barrier Reefs
3. Atolls - as
a. Deep sea atolls
b. Shelf atolls.
MINOR TYPES :
The minor reefs which could be seen are
1. Table reefs
2. The Faro
3. Micro atolls.
4. Knolls
5. Patch reefs and many more.
Importance of Corals:
1. Coral seas are typical ecosystems, most of them are shallow marine and a few are deep
marine
2. Coral ecosystems encompass a good platform for varieties of natural resources
3. Coral seas are good spots for ecotourism
4. Coral life are unique and exhibit a natural museum of wonderful marine life, which include
typical and beautiful plants and animals
5. Corals are also used as ornamental stones when they are naturally detached from the
basement
6. Coral ecosystems are good zones for improving marine habitat.
7. Study of coral ecosystems provide enormous data for biosphere- geosphere interaction
modeling
8. Corals are storehouses of organic calcium carbonate. These are good compounds for
pharmaceutical industries
9. Coral lagoons in some parts of the globe are considered to be good fishing zones. Eg. The
atolls of the Republic of Maldives are good examples.
10. It takes several decades to grow a few corals. The existing corals are to be protected and
the species are to be saved.
Ecology deals with organisms, populations, communities, ecosystems and the biosphere.
Marine ecology deals with the study of the environment and life in marine waters. It involves the study of
marine organisms and their habitat.
Their global distribution are studied in different branches of geography.
... People are integral parts of ecosystems and human wellbeing depends on 'ecosystem services', which are the benefits that people obtain from ecosystems (UNEP-WCMC, 2011). Balasubramanian (2011) recorded that the ocean is a major source of food, energy, mineral resources, and also controls the global climate. It is essential for all aspects of human well-being and livelihood. ...
... The finely balanced, highly complex, and largest of all the ecosystems, the ocean, is dominated by animal biomass (Balasubramanian., 2011) which covers twothirds of the Earth's surface. The upwelling regions, covering less than 1% of the world's ocean, are globally important marine biodiversity hotspots (Grecian et al., 2016). ...
Article
Full-text available
Environmental pollution and climate change are causing major changes in the marine environment. Coastal zones around the world are experiencing changes such as nutrient influx, resulting in altered plankton communities. The aim of this study was to determine the response of zooplankton to the changes in the environmental variables in the coastal zone of the Arabian Sea, Southwest Coast of India, over 10 years. Zooplankton abundance, chlorophyll-a concentrations, and water quality variables (rainfall, nitrates, phosphates, pH, water temperature, and salinity) were quantified from January 2010 to December 2019. Water temperature, pH, salinity, and phosphates increased steadily across the sites during the study period whereas chlorophyll-a and nitrates decreased. Rainfall abundance was not exhibiting any patterns or trends. The effects of the sampled environmental variables on zooplankton abundance were tested using generalized linear mixed models. Salinity and phosphates negatively affected the zooplankton abundance whereas water temperature, pH, and chlorophyll-a concentration had a positive effect. Coastal zones in southwest India are experiencing declining phytoplankton abundance due to a number of environmental factors. Reduced phytoplankton combined with altered environmental variables are having declining effects on zooplankton. This decline in zooplankton population has far reaching effects on biota in higher trophic levels including economically important organisms such as fishes.
... Aquatic ecosystems are living environments that are based on water. Freshwater ecosystems and marine ecosystems are the two types of aquatic ecosystems (Balasubramanian A 2011). A marine environment is defined as any ecosystem that exists in or near salt water, which implies it can be found anywhere on the planet, from a sandy beach to the deepest depths of the ocean. ...
... The finely balanced, highly complex, and largest of all the ecosystems, the ocean, is dominated by animal biomass (Balasubramanian., 2011) which covers twothirds of the Earth's surface. The upwelling regions, covering less than 1% of the world's ocean, are globally important marine biodiversity hotspots (Grecian et al., 2016). ...
Article
Full-text available
Environmental pollution and climate change are causing major changes in the marine environment. Coastal zones around the world are experiencing changes such as nutrient influx, resulting in altered plankton communities. The aim of this study was to determine the response of zooplankton to the changes in the environmental variables in the coastal zone of the Arabian Sea, Southwest Coast of India over 10 years. Zooplankton abundance, chlorophyll-a concentrations, and water quality variables (rainfall, nitrates, phosphates, pH, water temperature and salinity) were quantified from January 2010 to December 2019. Water temperature, pH, salinity and phosphates increased steadily across the sites during the study period whereas chlorophyll-a and nitrates decreased. Rainfall abundance was not exhibiting any patterns or trends. The effects of the sampled environmental variables on zooplankton abundance were tested using Generalized Linear Mixed Models. Salinity and phosphates negatively affected the zooplankton abundance whereas, water temperature, pH and chlorophyll-a concentration had a positive effect. Coastal zones in southwest India are experiencing declining phytoplankton abundance due to a number of environmental factors. Reduced phytoplankton combined with altered environmental variables are having declining effects on zooplankton. This decline in zooplankton population have a far reaching effects on biota in higher trophic levels including economically important organisms such as fishes
... The estuaries act as dynamic environment for feeding, breeding and nursery ground for most of the aquatic communities (Behera et al. 2013). Estuaries represent important ecosystems in coastal zones that are affected by various biotic and abiotic factors and have both ecological and economic importance (Balasubramanian 2011, Whitfield & Elliot 2011. At the same time, the estuaries are among the most modified and threatened environments (Blaber et al. 2000). ...
Article
Full-text available
The Göksu River estuary at the Mediterranean coast is among the major estuarine systems in Turkey. The aims of the present study were to analyse the distribution and qualitative and quantitative composition of the ichthyofauna in the Göksu River estuarine zone. Fish were sampled by different nets at four sites from November 2014 till June 2017. A total of 47 fish species were identified in the coastal marine zone and 32 species belonging to 16 families in the river estuary. Chelon auratus, Chelon saliens and Mugil cephalus were the dominant species and comprised over 75% of the total catch number. Marine fish dominated by species richness and abundance. Five alien species (Carassius gibelio, Gambusia holbrooki, Chelon carinatus, Oreochromis niloticus and Sillago suezensis) were caught in the estuary. Of them, Gambusia holbrooki had the highest abundance (77.6%). The indexes of species richness, diversity and evenness exhibited a strong spatial and temporal variation throughout the study period.
Chapter
This reference highlights the significance of marine ecosystems, encompassing seaweed beds, seagrasses, coral reefs, mangroves, estuaries, and protected areas, as a remarkable gateway to overcoming healthcare challenges and unlocking a rich trove of bioactive compounds for drug discovery. One of the key highlights of this book is its exploration of the development of marine bio-drugs, a field that demands collaboration among scientists from both academic and industrial fronts. The editors also include a prospective review on marine environments, emphasizing the necessity for big data, collective knowledge sharing, financial support, and streamlined administrative processes, all of which contribute to enhancing innovation in the drug discovery process. Another feature includes reference lists that allow researchers to explore topics of interest in depth. With twelve comprehensive chapters, this book extensively covers marine ecosystem biodiversity, productivity, protected areas, and the intricate interplay of biotic and abiotic factors that shape these ecosystems. Readers will learn about important bioactive compounds within marine organisms and how to use this knowledge to outline a strategy for bio-drug discovery. The book caters to a diverse audience of researchers, students, ecologists, microbiologists, pharmacologists, and biotechnologists who are engaged in studying the dynamic components of marine environments. By providing the latest insights and strategies in the realm of bio-drug discovery from marine resources, this book serves as an invaluable resource for scholars and professionals seeking to tap into the potential of these unique ecosystems.
ResearchGate has not been able to resolve any references for this publication.