Estuarine ecosystem. Pptx environmental microbiology

Estuarine ecosystem

1. ESTUARINE ECOSYSTEM S. BOOMIKA (BP231517). II M. Sc MICROBIOLOGY TIRUPATTUR.

2. INTRODUCTION The intertidal place zone terrestrial and the marine habitat meets, as estuary is a place where fresh water and salt water meet. It is a transition zone between the two aquatic eco system . Estuaries have main and remain close association with human, because many of the major cities of the world are establish on estuaries. In contrast to other ecotomes are transitional areas, estuaries have few species of permanent organisms.

3. DEFINITION OF ESTUARIES Several morphological features of coastlines, such as lagoons, sloughs, fjords and other shallow embayment’s are often considered estuaries. Estuary is a partially enclosed costal embayment where freshwater and sea water meet and mix. This definition implies the free communication of the sea with the fresh water source, at least during a part of a year.

4. Types of estuary Depending on form, Coastal Plain Estuaries: the sea level rising and filling an existing river valley. Tectonic Estuaries: the folding or faulting of land surfaces. These estuaries are found along major fault lines, like the San Francisco Bay areas in California Bar-built Estuaries: a shallow lagoon or bay is protected from the ocean by a sand bar or barrier is island. Fjords or U-shaped Estuaries: glacial action. Fjords are found in areas with long histories of glacier activity, like northern Europe, Alaska, and Canada .

5. ESTUARIES CLASSIFICATION classified in the way salinity gradients are formed. In most estuaries, there is gradient in salinity from full seawater at the meet of freshwater at the upper reaches. POSITIVE ESTUSRY SALT WEDGE ESTUARY: Estuaries where is substainal freshwater outflows and reduced evaporation [typical temperature zone estuaries], the freshwater moves out over the top of the salt water, mixing with it near the surface and reducing the salinity, leaving the deeper waters more saline. In such a situation, a cross section of the estuary shows isohalines [lines of equal salinity], which extend upstream at bottom. These estuaries are also called river dominated or stratified.

6. ESTUARIES CLASSIFICATION NEGATIVE OR EVAPORITE ESTUARY : In desert climate, where the amount of freshwater input to the estuary is small and the rate of evaporation high, a negative (or) evaporate estuary results. In a negative estuary, the incoming salt water enters at the surface and is some what diluted by mixing with the small amount of freshwater. The high evaporation rate, however, cause this surface water to become hyper saline. Hyper saline water is denser than seawater, sinks to the bottom and moves out of the estuary as a bottom current. A saline profile of such as estuary is the reverse of the positive estuary, with highest values at the bottom and lowest at the top.

7. ESTUARIES CLASSIFICATION SEASONAL (OR) INTERMITTENT ESTUARY : These estuaries are formed areas where there is a marked wet and dry season (Mediterranean climate) In the rainy season, they have freshwater input and are open to the ocean. In the dry season, they have no freshwater input, may become dry or stagnant, and are often cut off from the ocean by seasonal sandbars. Salinity in these estuaries varies not spatially but temporally.

8. ADAPTATION OF ESTUARINE ORGANISMS MORPHOLOGICAL ADAPTATION Few morphological adaptations among estuarine organisms can be attributed simply to living under conditions of fluctuating temperature and salinity. Most are adaptation to a given habitat, such as burrowing into mud. Mud dwelling or species in an estuary often have a lowest reproductive rate and lowered fertility. There are also certain morphological adaptation among vascular plants living in estuaries and salt marches.

9. All have a special tissue, the aerenchyma that supplies oxygen to the roots embedded in anoxic mud. Other have extensive stores of carbohydrate signet roots to provide a sugar to cope with salinity fluctuation. Many also have high lignin content ,which may be an adaptation to the plant to cope with high internal salinity. Abundant stomata and thin cuticle are suggestive of high transpiration rates.

10. CONTINUES … PHYSIOLOGICAL ADAPTATION : The adaptation required for estuarine life are those that maintain the ionic balance of body fluids is fluctuating external salinity. Osmosis is the physical process in which water passes through a semipermeable membrane that separate two fluids of different salt concentration, moves from the areas of lower to higher salt concentration. The ability to control the concentration of salts or water in internal fluids is called Osmoregulation. Their ability to penetrate estuaries is limited to their tolerance for changes in their internal fluids. Osmoregulators are organisms that have physiological mechanisms to control the salt content of their internal fluids.

11. ADVANTAGES OF ESTUARY Estuaries are essential habitats for fish, insects and other wildlife. Provides goods and services that are economically and ecologically indispensable. commercial fishing and recreational opportunities Filtration process creates cleaner and clearer water, which benefits both people and marine life.

12. DISADVANTAGES OF ESTUARY Estuary has too many nutrients, too much algae will grow, creating algae blooms. Algae blooms block sunlight and can suffocate fish and plants by using up valuable oxygen from the water. Large- Scale conversion by draining, filling, damming, or dredging. These activities result in the immediate destruction and loss of estuarine habitat. Evaporation exceeds freshwater. The back of the estuary becomes a source of dense water saltier than seawater.