Why Are Coastal Wetlands
Important to Fish?
Wetlands are among the most important environments on earth. They render many services to nature and humans, making them very valuable from both an ecological and socio-economical point of view.
Ecological importance: Wetlands provide habitat, food, and protection to many different species of animals including fish, birds, mammals, reptiles, and invertebrates, including endangered and commercially important species of fish, shrimp, crabs, and shellfish. Wetlands can also function as natural “filters” by removing excess sediments, nutrients, and contaminants that come from the associated watershed (area of land that drains to a particular body of water such as a river, lake or wetland). By doing this, wetlands provide cleaner water to their inhabitants and to plants and animals of adjacent environments.
Socio-economic importance: The socio-economic value of wetlands comes from direct and indirect use of their resources. Forested wetlands, for example, provide firewood, building materials, and wood for charcoal production. Humans have also used wetlands as a source of medicinal plants and food. An indirect, but well-recognized value of wetlands is their role as nurseries for important commercial and recreational fish species. Wetlands also are valuable for their role in storm protection, shoreline stabilization, flood attenuation, water quality improvement, and tourism.
Salt marshes: the "farms" of the coast : Salt marshes, some of the most common coastal wetlands, are very productive natural systems. The mixing of nutrients from land and sea that occurs in salt marshes produces more organic matter per acre than the richest Midwestern farmland. A small percentage of salt marsh grasses are eaten directly by fish and invertebrates, but most is decomposed by fungi and bacteria, producing an organic soup (called detritus) that feeds organisms such as amphipods, shrimp, crabs, snails, shellfish and finfish. These organisms in turn support a broad food chain that includes a variety of shellfish and finfish populations.
Salt marshes are important to numerous species that are in the salt marsh permanently or temporarily. Salt marsh plant stems create a very dense canopy with a diverse community of organisms growing on them. These organisms (known as "epiphytes") are a source of food for herbivores and a source of organic matter for a complex, mobile, detrital food web. Rising and falling tides move both the organic soup and small feeding organisms between the salt marsh and adjacent coastal waters. The abundance of small habitats within a salt marsh allows for numerous organisms to hide from predators, feed without expending much energy, grow faster, and raise young.
In addition to the transient organisms, salt marshes shelter species that may spend their entire life in the salt marsh. Although many species leave salt marshes with the ebbing tide, killifish take refuge in small salt marsh ponds, fiddler crabs hide in burrows, and mussels close their shells and await the next flood tide. These and other salt marsh residents are very important in cycling material within the salt marsh and as food sources for transient shellfish and fish.
Salt marshes and estuaries provide essential habitat for over 75 percent of the fish caught commercially and 80-90 percent of the fish caught recreationally. Popular species such as spotted seatrout, scup, butterfish, mullet, spot, pigfish, gag grouper, Pacific herring, white grunt, summer flounder, menhaden, pink shrimp, spiny lobster, Atlantic croaker, and blue crab all use salt marshes as juveniles or adults for feeding and refuge, moving into the salt marsh on the flooding tide and out on the ebb tide. Bluefish and striped bass, important recreational species, depend on salt marshes for the small fish that are their food. One of the most important commercial species, hard clam, depends on salt marshes for the detrital food chain that supports its growth. Menhaden, the second highest commercial species landed by weight in the Unites States in 2003, has a particularly strong tie to salt marshes and their detrital food chain. All of these species, and many others too numerous to list here, depend on healthy abundant salt marshes to support their populations.
