Estuaries ecosystem

Estuaries Ecosystem : Where River Meets Ocean

Everything about estuary ecosystem has been elaborated including Introduction, Types, Physical and Chemical Characteristics , Biota, Marsh Lands, Mangrove Forests, Food Web, Threats, Conservation, Restoration etc....

1. MAHATMA GANDHI CENTRAL UNIVERSITY MOTIHARI BIHAR ESTUARIES ECOSYSTEM Presented By: Raviranjan Kumar Gupta M.Sc Zoology MGCU2019ZOOL4012 Mahatma Gandhi Central University, Motihari Bihar Special Thanks: Dr. Kundan Kishor Rajak Mahatma Gandhi Central University, Motihari Bihar

2. CONTENTS Introduction Types Of Estuaries Physio-Chemical Characteristics Biota Of Estuarine Ecosystem Salt Marshes Mangrove Forests Food Web In Estuarine Ecosystem Productivity Of Estuary Importance Of Estuaries Threats To Estuarine Ecosystem Conservation And Restoration Of Marsh Lands References

3. INTRODUCTION An Estuary is a semi-enclosed areas where freshwater from rivers meet ocean water , the two being mixed by the action of tides. Estuaries are highly productive ecosystem and characteristically are more productive than the adjacent sea or river . The degree of mixing of salt and freshwater depends on the morphology of the estuary basin , the rate and volume of freshwater and the amount of tidal flow. The Yaquina Estuary (Courtesy: The Wetlands Conservancy)

4. In Estuaries, the salty ocean mixes with a freshwater river , resulting in brackish water. Brackish water is somewhat salty but not as salty as the ocean . Brackish water has higher dissolve salts than of fresh water. i.e , 0.5-35 % . An estuary may also be called a bay , lagoon , sound or slough . Estuary possess unique ecological features and biotic communities. Estuaries are most productive system of world. e.g , The Coast Of Kerala Continue……… Diagram Showing Mixing Of Freshwater and Saltwater and Formation Of Brackish Water

5. Coastal plain estuaries are created when sea level rise and fill in an existing river valley . The Chesapeake Bay , on the East Coast of the United States , is a coastal plain estuary. The Chesapeake Bay was formed at the end of the last ice age . Massive glaciers retreated, leaving a carved-out landscape behind. The Atlantic Ocean rushed to fill in the wide coastal plain around the Susquehanna River , creating a large estuary known as a Ria:A drowned river mouth . There are four types of estuaries based on how they created TYPES OF ESTUARIES 1.COASTAL PLAIN ESTUARIES The Chesapeake Bay

6. Tectonic Estuaries are caused by the folding or faulting of land surfaces . These estuaries are found along major fault lines, like the San Francisco Bay area in California . California’s San Francisco Bay is a tectonic estuary. 2 .TECTONIC ESTUARIES San Francisco Bay San Francisco Bay turns brown after nonstop storms: Deposition Of Clay sized particles from 2 central rivers

7. Bar-Built Estuaries form when a shallow lagoon or bay is protected from the ocean by a sand bar or barrier island. Eastern Seaboard and The Gulf Coast Of North America are examples of Bar-Built Estuaries. 3.BAR-BUILT ESTUARIES Bar-Built Estuaries

8. Fjords are U-shaped valleys formed by glacial action . Fjords are found in areas with long histories of glacier activity like Northern Europe, Alaska and Canada . Puget Sound is a series of Fjords estuaries in the U.S. state of Washington . 4. FJORDS Puget Sound Series Of Estuaries

9. Estuaries having large variation in several parameters and create stressful environment for organisms. This is the reason that large organisms are less in number in this area than smaller organisms. Estuaries are dominated by soft muddy ( combination of silt and clay) substrate and is rich in organic matter. When the strong current prevails, the substrate will be sand . I f current is calm , the substrate is only fine slit , will settle out. PHYSIO-CHEMICAL PROPERTIES CHARACTERISTICS Different zone has different climatic conditions, making stressful for organisms

10. The Water temperature in estuaries, except fjords , varies markedly because of their shallow depths and large surface area. It heats up and cools down more rapidly under atmospheric conditions & the reason for this is freshwater input. The surface water have the greatest temperature range & the deeper water have lower temperature range. Temperature CHARACTERISTICS Temperature Variation over the year Months Temperature Cooler Water Sinks At Bottom And Warmer Water At Surface

11. All the variations i.e , the salinity, the texture of substrate, temperature, organic matter content and available oxygen are controlled by wave action and currents . The wave action in estuary is small . As a result, there is deposition of fine sediments and development of rooted plants. Wave Action And Its Effect CHARACTERISTICS Deposition of fine sediments as tidal sand banks and development of rooted plants

12. When dense , salty seawater flows into an estuary , it has an estuarine current . High tides can create estuarine currents . Saltwater is heavier than freshwater, so estuarine currents sink and move near the bottom of the estuary. When less-dense freshwater from a river flows into the estuary , it has an anti-estuarine current . Anti-estuarine currents are strongest near the surface of the water . Heated by the sun , anti-estuarine currents are much warmer than estuarine currents . Estuarine Current CHARACTERISTICS

13. Current in estuaries are caused primarily by tidal action and river flow . Velocities up to several knots can occur. The highest velocities occur in middle whereas in the bottom and side bank the velocity is lowest. The erosion & deposition in the estuaries are due to currents which is a natural cycle. However, In estuaries deposition exceeds erosion so there is a net accumulation of silt. During dry part of the year, water movement is severely reduced leading to stagnation, reduced oxygen content, formation of algal blooms and incidence of fish kills. Current Velocities And Its Effects CHARACTERISTICS Lowest velocity at bank and bottom Highest velocity at middle

14. The water of estuaries is turbid because of the great number of particulates in suspension in the water. The turbidity is minimum near the mouth and increase with distance inland. The major ecological effect of turbidity is a marked decrease in the penetration of light . Thus, in turn decreases photosynthesis by phytoplankton and benthic plants, thereby reducing productivity. Turbidity CHARACTERISTICS Ecological Effect Of Turbidity

15. Oxygen is also the most important factors in the estuary system. Since the solubility of oxygen in water decreases with increase in temperature and salinity , so the amount of oxygen varies with these parameters. Oxygen is severely depleted in the substrate. The high organic content and bacterial population of the sediments exert a large oxygen demand on the water. Estuarine sediments are ,therefore, anoxic below the first few centimeters, unless they have large no of burrowing animals such as ghost shrimp Callianasa and hemichordate worm Balanoglossus which by their activities oxygenate lower sediment layers. Oxygen CHARACTERISTICS Dissolve Oxygen Pattern

16. In Estuaries, water level and salinity rise and fall with the tides. These features also rise and fall with the seasons . During the rainy season , rivers may flood the estuary with freshwater and lowers the salinity. During the dry season , the outflow from rivers may slow to a trickle, the estuary shrinks and becomes much more saline . During the storm seasons , storm surges and other ocean waves may flood the estuary with salt water . Most estuaries, however, are protected from the ocean’s full force , ocean waves and wind by Geographical features such as reefs , islands , mud and sand . Salinity CHARACTERISTICS Profile of an idealized estuary Types of species living in an idealized estuary in relation to salinity

17. Salinity also varies with depth in the estuary. The salty seawater is more dense and stays on the bottom . It flows in along the bottom in what is frequently known as a salt wedge . Meanwhile, the fresher, less dense water from the river flows out on the surface. It moves up the estuary on the rising tide , then recedes as the tide falls . This means that organisms that stay in one place are faced with dramatic fluctuations in salinity . They are submerged under the salt wedge at high tide and under low-salinity water at low tide. If the area has a diurnal tide , the organisms are subjected to two shifts in salinity every day: one as the tide moves upstream and a second as it retreats. In an estuary with semidiurnal tides, salinity changes four times a day. Salinity And Its Effects CHARACTERISTICS At high tide the crab is covered by water with a salinity of 35‰. At low tide it is covered by water with a low salinity, between 5‰ and 15‰.

18. The biota of estuaries is, in turns regulated by degree of mixing . Estuarine diversification is lower than river or marine because of tremendous variation in physical environment. Major species are restricted to the estuarine situation , such as Oyester & Crabs and those that come from sea, such as Shrimp . Very few species are derived from freshwater and only those that are capable of osmoregulation in the saltier environment . Estuaries are nursery ground for vast number of marine animals shrimps and crabs to fishes. Biota of Estuarine Ecosystem BIOTA OF ESTUATINE ECOSYSTEM

19. Although not always evident, primary producers do flourish on mudflats ( The bottoms of estuaries that become exposed at low tide often form mudflats ) A few seaweeds—like the green algae Enteromorpha sea lettuce, and some red algae—grow on bits of shell. Bacteria and archaea are extremely abundant on mudflats. They decompose the huge amounts of organic matter brought in by rivers and tides. When the oxygen is used up by decay, some bacteria produce hydrogen sulfide. This in turn is used by sulfur bacteria, chemosynthetic bacteria that derive energy by breaking down sulfur compounds like hydrogen sulfide. Diatoms and bacteria, including photosynthetic bacteria, actually account for most of the primary production on mudflats Primary Producers BIOTA OF ESTUATINE ECOSYSTEM Enteromorpha Red Algae

20. The dominant animals on mudflats burrow in the sediment and are known as infauna . Burrowers, like the fat innkeeper ( Urechis caupo ), polychaete ( Hesperonoe adventor ), a crab ( Scleroplax granulata ), a fish ( Clevelandia ios ) and other guests. Mudflat inhabitants that feed on detritus are:- Deposit Feeders- Animals feeding on organic matter that settles in the sediment. Suspension Feeders- Animals , including filter feeders, that feed on particles suspended in the water column . Many deposit feeders and some other members of the infauna are known as bioturbators because they move and mix sediment when burying or digging . Bioturbation helps in the oxygenation of sediment, a most important role in the case of the typically anoxic sediments of estuaries . Infauna BIOTA OF ESTUATINE ECOSYSTEM Infauna

21. The Protozoans , nematodes, and many other minute animals that compose the meiofauna also thrive on detritus. The meiofauna are also known as interstitial animals . The larger burrowing animals, or infauna , include many polychaetes . Most are deposit feeders . Other polychaetes are suspension feeders that filter water or extrude tentacles to collect the detritus that falls from the water column. Meiofauna BIOTA OF ESTUATINE ECOSYSTEM a&b. Nematoda c. Tardigrada d . Kinorhyncha

22. Very few mudflat animals can be classified as epifauna , those that either live on the sediment surface or are attached to a surface as sessile forms . Crabs , Mercenaria mercenaria , Mya arenaria , Macoma , ghost, mud snail ( Upogebia ) shrimps and Uca are some examples for epifauna . Some of these are of considerable commercial importance. Epifauna BIOTA OF ESTUATINE ECOSYSTEM Epifauna

23. M ost important predators in the mudflat community are fishes and birds. Fishes invade mudflats at high tide, whereas birds congregate at low tide to feed. The most significant predators on mudflats are wading shorebirds. These include the willet, godwits, dowitchers , and many species of plovers and sandpipers such a curlews and phalaropes. They feed on polychaetes , ghost shrimps and other small crustaceans, clams, and mud snails . Predators BIOTA OF ESTUATINE ECOSYSTEM Differences in the bill length of wading shorebirds

24. Estuaries in temperate and subarctic regions worldwide are usually bordered by extensive grassy areas that extend inland from the mudflats. These intertidal areas are partially flooded at high tide and are known as salt marshes , or sometimes tidal marshes . Sometimes they are grouped with coastal environments flooded at high tide and with freshwater marshes and collectively called wetlands. Salt Marshes plants are Spartina alterniflora , Spartina foliosa , Spartina patens. It is characterized by a large variety of plants resistant to salt spray, like salt grasses and several species of pickleweed . SALT MARSHES

25. SALT MARSHES Bacteria The muddy salt-marsh substrate is home to decay bacteria , diatoms , and thick mats of filamentous green algae and cyanobacteria. Bacteria play a crucial role by decomposing the large amounts of dead plant material produced in the salt marsh. These bacteria and the partially broken-down organic matter are a major source of the detritus that feeds many of the inhabitants of the estuary. Some bacteria are nitrogen fixers that enrich the sediment . filamentous green algae Diatoms Bacteria

26. SALT MARSHES Salt Marsh Animals The Some burrowing animals of mudflats also inhabit salt marshes. N ematodes , small crustaceans , larvae of land insects, and other small invertebrates live among the algal mats and decaying marsh plants . Crabs are conspicuous inhabitants of salt marshes . Other marsh crabs are scavengers that eat dead organic matter. Some of these species live in burrows. Marsh plants provide shelter and food to many marine and land animals. Abludomelita obtusata Crabs Lobster Krill Shrimp

27. MANGROVE FORESTS Mangroves are a group of  trees and shrubs  that live in the  coastal intertidal zone . All of these trees grow in areas with low-oxygen soil , where slow-moving waters allow fine sediments to accumulate . Mangrove forests only grow at tropical and subtropical latitudes near the equator because they cannot withstand freezing temperatures. Mangrove forests provide food , fuel , timber and medicines either directly or indirectly. Mangrove forests stabilize the coastline, reducing erosion from storm surges, currents, waves, and tides. The intricate root system of mangroves also makes these forests attractive to fish and other organisms seeking food and shelter from predators . Some common species are red mangrove ( Rhizophora mangle ), black mangrove( Avicennia germinans ) and the white mangrove( Laguncularia racemosa ).

28. MANGROVE COMMUNITIES Distribution of mangrove species in West Coast estuaries C omplex food web of Mangrove communities

29. FOOD WEB IN ESTUARINE ECOSYSTEM Generalized food webs in estuarine ecosystems. Salt marshes (left) occur in temperate regions, mangroves (right) in the tropics.

30. The high productivity results from estuaries being nutrients traps for both physical ( Based on the degree of mixing ) and biological ( Rapid recycling ) reasons. Also estuarine producers , which include seaweeds and marsh grasses as well as benthic algae and phytoplankton , are capable of nearly year-round photosynthesis . The higher the fluctuation of water level , the higher the productivity , the tides serving to remove waste and to transport food and nutrients . Estimates of primary production range from 130 to nearly 6,000 grams dry weight/m 2 /year for cordgrasses in salt marshes on the Atlantic coast of the United States. Why High Productive ?

31. The Estuaries are tremendously productive and are home to large numbers of organisms, many of which are of commercial importance . Estuaries also provide vital breeding and feeding grounds for many animals. Estuaries are important stopover and wintering areas for many species of migratory birds. The open spaces offer them safety from natural enemies, and food is plentiful . The worldwide economic value of marine wetlands as sources of food and as nurseries of many food species, in recreation and tourism, as sources of wood and other materials, in protection against storms and erosion , as well as in the maintenance of biodiversity and water quality , is enormous. Estuarine environments are of great cultural and economic importance to the general community . As transition zones between land and water , estuaries are invaluable laboratories for scientists and students studying the complexity of biology, geology, chemistry, physics, history and social issues. Tourism , fisheries, and other commercial activities thrive on the wealth of natural resources estuaries supply. In New South Wales , commercial fishing around estuaries is worth over $80 million per year, with recreational fishing estimated to be worth $500 million per year. The building industry sources sand and gravel from estuary areas worth over $100 million per year. The protected coastal waters of estuaries also support important public infrastructure, serving as harbours and ports vital for shipping, transportation and industry . Importance Of Estuaries

32. The human intrusion in marine wetlands, particularly in highly productive salt marshes and mangrove forests, have been disastrous . Countless have been obliterated , and many surviving ones are in danger of disappearing . All around the globe estuaries are being dredged to make marinas , artificial harbors , and sea-ports . Others are filled to create everything from industrial parks and urban development to garbage dumps . The dredging of navigation channels increases the exposure of estuaries to wave action, which often results in the destruction of salt marshes . Another problem in some estuaries is the reduction or elimination of normal freshwater input when rivers are dammed or diverted . Sediment input from rivers is decreased so that erosion of sediments by tides is not re- plenished . The opposite can also be a problem. Deforestation and agriculture brings about an increase in sediment , which in estuaries like Chesapeake Bay, decreases water quality and increases pollution . HUMAN INTRUSION AND THREATS TO ESTUARIES

33. The destruction of salt marshes by human activities is a major worldwide problem . The restoration of disturbed salt marshes to their natural condition is being carried out as part of efforts to protect and preserve coastal wetlands. Some biologists encourage the natural regeneration of disturbed salt marshes, but others prefer to accelerate recovery by replanting dominant species , particularly cordgrass ( Spartina ). For example, the University of Southern Mississippi operates a nursery that grows salt marsh plants that are transplanted in damaged marshes . The success of replanting depends on factors such as wave action and tides , water chemistry (salinity, dissolved nutrients), and the substrate (slope, sediment size, oxygen content ). Recovery can take many years , and the length of the recovery period depends on the degree of disturbance , environmental factors , and the relative maturity of marshes . The more mature marshes take the longest to recover. CONSERVATION AND RESTORATION OF MARSH LANDS

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