Aquatic ecosystem

[17] In addition to environmental functions, aquatic ecosystems are also used for human recreation, and are very important to the tourism industry, especially in coastal regions.

[20] There are a growing number of cases where predation by coastal herbivores including snails, geese and mammals appears to be a dominant biotic factor.

Algae use solar energy to generate biomass from carbon dioxide and are possibly the most important autotrophic organisms in aquatic environments.

These two sources combine to produce the extraordinary production of estuaries and wetlands, as this autotrophic biomass is converted into fish, birds, amphibians and other aquatic species.

For example, there are giant tube worms (Riftia pachyptila) 1.5 m in length and clams (Calyptogena magnifica) 30 cm long.

Some of the important abiotic environmental factors of aquatic ecosystems include substrate type, water depth, nutrient levels, temperature, salinity, and flow.

[29] Similar over-abundance of algae in coastal environments such as the Gulf of Mexico produces, upon decay, a hypoxic region of water known as a dead zone.

The degree of salinity in an estuary or delta is an important control upon the type of wetland (fresh, intermediate, or brackish), and the associated animal species.

Chemical alterations include changes in the loading rates of biostimulatory nutrients, oxygen-consuming materials, and toxins.

[16] Climate change driven by anthropogenic activities can harm aquatic ecosystems by disrupting current distribution patterns of plants and animals.

It has negatively impacted deep sea biodiversity, coastal fish diversity, crustaceans, coral reefs, and other biotic components of these ecosystems.

The environmental history of the Great Lakes of North America illustrates this problem, particularly how multiple stresses, such as water pollution, over-harvesting and invasive species can combine.

[33] Lake Pontchartrain along the Gulf of Mexico illustrates the negative effects of different stresses including levee construction, logging of swamps, invasive species and salt water intrusion.