Water Platter and Koi – Ecosystems
An ecosystem is defined by all living and non-living objects in an area. Each ecosystem is as diverse as all the items found within it from forest to ocean and mountain to desert, and particularly fresh water lakes and ponds, like the one featured here.
“Freshwater ecosystems are aquatic systems which contain drinkable water or water of almost no salt content. Freshwater resources include lakes and ponds, rivers and streams, reservoirs, wetlands, and groundwater. The United States derives many benefits from these freshwater resources. They provide the majority of our nation's drinking water resources, water resources for agriculture, industry, sanitation, as well as food, including fish and shellfish. They also provide recreational opportunities and a means of transportation. In addition, freshwater ecosystems are home to numerous organisms (e.g., fish, amphibians, aquatic plants, and invertebrates). It has been estimated that 40% of all known fish species on Earth come from freshwater ecosystems (NatureServe– Rivers of Life: Critical Watersheds for Protecting Freshwater Biodiversity). Unfortunately, rivers and streams are also among the most endangered habitats.
The rates of extinction of freshwater species and the number of endangered freshwater species are alarming. For example, the Nature Conservancy coupled with the Natural Heritage Network report that since the first European settlement, 21 out of 822 [American native] fish species have become extinct.
Species of concern include:
· two-thirds of the nation’s freshwater mussels are at risk of extinction; almost 1 in 10 may already have vanished forever.
· half of all crayfish species are in jeopardy
· over 40% of stoneflies are at risk
· freshwater fishes and amphibians are doing little better, with about 40% of the species in these groups also at risk
· dragonfly and damselfy species have about 18% at risk.
The World Resources Institute on Biodiversity has also reported that almost 50% of freshwater snails in the Southeastern United States are now endangered or extinct due to channelization and impoundment of rivers.
Some major groups of organisms known to inhabit freshwater ecosystems include vertebrates (e.g., fish, amphibians, reptiles, birds, and mammals), invertebrates (e.g., protozoan, myxozoans, rotifers, worms, mollusks), plants, algae, fungi, and bacteria. Infectious agents such as viruses may also be present. As in marine environments, phytoplankton and zooplankton form the base of the food chain. Periphyton, macrophytes (aquatic plants), and insects are also found in freshwater environments, along with various bird species like osprey, ducks, and raptors.
Despite all of their value and importance, many freshwater ecosystems are being severely damaged by human activities. The major threats to freshwater biodiversity include runoff from agricultural and urban areas, the invasion of exotic species, and the creation of dams and water diversion. Overexploitation and pollution also threaten groundwater supplies. These kinds of threats and others have already significantly impacted the biodiversity within these ecosystems.”
For more information, visit the Environmental Protection Agency website: www.epa.gov.