Animals of Estuaries
The animals of estuaries and related wetlands such as marshes and swamps are tremendously important not only as denizens of their environment but also for their role in marine communities and in human economies. The best known estuarine animals are detritus feeders such as oysters, clams, lobsters and crabs. Several insect larvae, annelid worms and mollusks enter the estuary from fresh water, most near shore marine zooplankton can also be found partway into the estuary along with 4everal types of larger animals. Most important of all this is that estuaries are the nursery ground for a vast number of marine animals ranging from shrimps and crabs to fishes. . The presence of high nutrient level in the estuaries results in a very high level of production within the detritus food chain. Nutrient matter is broken down by bacteria at a very high rate and recycled into soluble form. Plants adapted to the difficult conditions of salinity found in the estuary can maintain a high level of productivity The amount of nutrient rich organic detritus also allow a high level of productivity for detritus eating animals. The estuarine ecosystem is complex and significant. It is also vulnerable since estuaries have served as conduits for shipping and as sites for cities throughout human history.
Estuaries are inhabited by animals that are adapted to a changeable environment, to be sure, but their strategic location has led to a substantially greater degree of human alterations than in any other ecosystem. Many people look upon estuaries as area whose greatest value is to be filled and built upon, or to serve as dumping grounds for garbage, sewage and industrial wastes. This is not true and their tremendous productivity can be made to serve as a food source for people - indeed, it is already a very important food source in the far East -and almost all the major marine fisheries of the world are totally dependent on the estuaries for their continuance, because the-adult fishes often resort to estuaries for laying eggs, i.e., spawning.