User:Patronus19/Tidal marsh

Intro, 3rd paragraph:
The state of tidal marshes can be dependent on both natural and anthropogenic processes. In recent periods, human practices, small and large scale, have caused changes in ecosystems that have had a significant impact on the preservation of tidal marsh ecosystems. Some smaller scale changes include headward (i.e. upstream) erosion and coastal development. Large system changes include pollution and sea level rise (from climate change). These changes are all putting pressure on tidal marshes.

Types
Tidal marshes can be found in two main places: coasts and estuaries. Coastal tidal marshes lie along coasts and estuarine tidal marshes lie inland within the tidal zone. Coastal tidal marshes are found within coastal watersheds and encompass a variety of types including fresh and salt marshes, bottomland hardwood swamps, mangrove swamps, and palustrine wetlands. Estuarine tidal marshes are found in estuaries, areas where freshwater streams flow into brackish areas.

They can be categorized based on salinity level, elevation, and sea level 1,7 in original article. Tidal marshes are commonly zoned into lower marshes (also called intertidal marshes) and upper/ high marshes, based on their elevation above sea level. A middle marsh zone also exists for freshwater tidal marshes. Location determines the controlling processes, age, disturbance regime, and future persistence of tidal marshes. Tidal marshes are differentiated into freshwater, brackish, and salt according to the salinity of their water 1 in original article.

Freshwater
Freshwater tidal marshes live more inland than saltwater marshes, but their proximity to the coast still allows for daily fluctuations from tides. The inland location allows for a majority of the water content to be from freshwater stream discharge, meaning the salt content is low.

Tidal freshwater marshes are further divided into deltaic and fringing types (4 in original article).

Extensive research has been conducted on deltaic tidal freshwater marshes in the Chesapeake Bay 5 in original article, which were formed as a result of historic deforestation and intensive agriculture6 in original article.

Freshwater tidal marshes are highly productive and are home to a variety of organisms. There is a variety of vegetation that can reside in freshwater marshes. There is also a vast amount of insects which attract birds, such as wrens and warrens. Aquatic birds, such as ducks and herons, also live in these marshes. Freshwater tidal marshes also serve as spawning grounds for anadromous fish, such as shad and herring. These fish spend most of their lives in saltwater areas, but return back to freshwater during reproduction.

Tidal freshwater marshes are also highly productive, generate a large amount of good quality biomass. They also serve as good waste treatment areas, based on denitrification potential.

Saltwater
Saltwater tidal marshes live on coastlines in areas that are not completely exposed to the open ocean. The volume of water is dependent on the tides. Plant variation throughout marshes can be due to differences in tide exposure and frequency.

Some different types include bottomland hardwood swamps, mangrove swamps, and palustrine wetlands9 in original.

Saltwater tidal marshes are correlated with higher decomposition rates and lower denitrification rates.

Island and Barrier Island
Tidal Marshes also form between a main shoreline and barrier islands. These elongated shifting landforms evolve parallel and in close proximity to the shoreline of a tidal marsh10 in original. Many become fully submerged at high tide, and become directly attached to the mainland when at low tide. Barrier island formation includes mechanisms such as offshore bar theory, spit accretion theory, and climate change11,12 in original.