What's in a Wetland -- Overview

Wetlands are extremely varied ecosystems comprised of flat or depressed areas along the edges of lakes and oceans. Wetlands occur when the top levels of soil are frequently exposed to large amounts of water. According to the EPA, wetlands “is the collective term for marshes, swamps, bogs, and similar areas found in generally flat vegetated areas, in depressions in the landscape, and between dry land and water along the edges of streams, rivers, lakes, and coastlines” (EPA). 

Because of their extreme diversity and variation, wetlands can be found in almost any climate and location. In fact, there are wetlands on every continent except Antarctica. Some examples of wetlands around the world are (WWF):

The Pantal Wetlands in Brazil, Bolivia, and Paraguay

Pantal Wetlands

 Wasur National Park, Indonesia

Wasur National Park

 Okavango Wetlands in Botswana

Okavango Wetlands

The above photos make apparent the immense variation in the appearances and locations of wetlands. The wetlands above come from three different continents, and rang from having small shrubs and moss to tall trees and reeds.

There are also wetlands found throughout the United States. Our wetlands are generally divided into two types: inland wetlands and coastal wetlands. Inland wetlands are found in the interior of North America in depressions and flat land along the edge of rivers and lakes. In contrast, coastal wetlands are found off the shorelines of the Pacific, Atlantic, and Gulf coasts (EPA)

The variation in wetland ecosystems give rise to a large biodiversity. In many wetlands, the climate alternates between wet and dry. During some of the year the ground is almost completely covered in shallow water, while at other times it is very dry. Additionally, especially in coastal wetlands, the mixture of freshwater and saltwater create an environment of varying salinity. The plants and animals of wetlands have adapted well to these varying conditions, the wetlands themselves create both aquatic and terrestrial habitats. Some examples of these habitats are saltmarshes, which host vegetation such as pickleweed and eel grass. Mudflats are the chosen habitat of mollusks and some marine worms. Fish nurseries commonly occur in the deep water tidal channels in coastal wetlands. In addition to these permanent wetland residents, migratory birds visit wetlands during spring and fall to feed and rest. Wetlands in the Central California Coast are particularly important for these birds, as it is part of one of the four most important bird migration routes in North America. (SLO-Coast)

Study Area Map - Elkhorn Slough

Elkhorn Slough - Aerial View

Elkhorn Slough Study Map - MTYCounty.com

An Estuarine salt marsh -- The Elkhorn Slough

A slough is a type of coastal wetland, with soft, muddy, and swamp-like ground. Sloughs are typically found in river deltas close to the ocean. They contain both fresh and salt water, creating this unique estuarine ecosystem.


The Elkhorn Slough  is a meandering waterway located on the Monterey Bay near the town of Moss Landing on the central coast of California. It is used for recreation, kayaking, fishing, and agriculture. The immense biodiversity makes the Elkhorn perfect for recreational use.There are 5 miles of trails in the slough, and staff give guided tours. People can also go kayaking or boating, both of which offer an opportunity to view sea otters. The slough is especially known as a great place for birdwatching because there are more than 300 species of birds living in the slough at any given time. Hunting and fishing are not allowed in the National Reserve, but other parts of the slough maintained by private organizations allow people to fish and hunt. The Moss Landing harbor is also a great place for people to eat, shop, and enjoy tours at the Visitors' Center.

The Elkhorn's Ecosystem

Aquatic Habitats: Salt marshes Include upper regions of tidal water near the coast. Fresh water flowing into the slough creates some brackish marsh areas, and the main marsh is covered with plant life. Fresh water areas include wet meadows, riparian corridors and freshwater marshes. These are home to many plants and reptiles such as the Santa Cruz Long-toed Salamander. Much of the fresh water around the edges of the slough have been lost due to agriculture. The Harbor of the slough leads directly to the Monterey Bay. The harbor is home to many fish and animals such as otters, sea lions and topsmelt.

Terrestrial Habitats: Coastal prairie and coastal scrub areas include many plants, mammals, reptiles, and insects. The coastal prairie is actually home to several endangered wildflowers. 99% of california grasslands have been lost in the last 200 years making them one of the most endangered ecosystems in the U.S. Species include Coyote Brush, California Poppy, and the white-tailed kite. The maritime chaparral includes endemic manzanitas, bobcats, and mountain lions. The Coast Live Oak Woodlands holds over 200 animal species including mammals birds and reptiles. Oaks are most common, but in the watershed there are also eucalyptus, conifers and riparian woodlands.

The Slough's Flora & Fauna: There are more than 340 bird species, several of which are rare or endangered, such as the Brown Pelican and the Peregrine Falcon. In the water there are both marine and estuarine fish. Some come to feed, mate and spawn before heading back to the ocean. These fish include the Bat Ray and the Leopard Shark.Some of the mammals in the slough include Sea Lions, Sea Otters, Harbor Seals, and even Bobcats and Mountain Lions. The slough contains over 400 plant species. Over 100 of these species are non-native plants from asia and europe. Native plants include the California Poppy, Santa Cruz Tarplant and Pickle Weed.

Past, Present, and Future

Historical Look: The slough's health has always been tied to sea levels. During the last ice age, sea level was about 120 m below current levels, and there was little wildlife presence. About 18,000 years ago, glaciers began to melt and sea levels rose to roughly where they are today. At first Elkhorn Slough had high-energy tidal activity as water rushed into the inlet, but about 8,000 years ago the tidal force decreased and sediment began to accumulate. As more sediment filled the area mudflats (areas of mud deposited by tides or rivers) and salt marshes (coastal grassland regularly filled with ocean water) formed.

Present Day -- Human Impacts:
Global Warming -- The Elkhorn Slough has been in danger for several years because of the effects of global warming. It is especially susceptible to rises in tide; because it sits at sea level, even moderate rises in tide can overwhelm the ecosystem and be disastrous for local species. 
Land Development -- Development of the land around the slough has led to tidal restriction which causes tidal erosion and marsh loss. The Moss Landing Harbor, built in 1947, had a terrible impact on the slough. The vegetation that was cleared to build the harbor left marshland farther inland more susceptible to erosion; this has resulted in significant marsh die-back in the last 60 years. Finally, as part of the development of the land, a local power plant was constructed near the slough. The plant is not only aesthetically unappealing, but it also limits the available land for plants animals of the slough, and it adversely affecting the water quality.

Agriculture -- Cattle farms pollute the soil with waste and grazing causes soil erosion stripping the land of nutrients. The Invasive non-native plants and animals mentioned above are disrupting the native species and competing for a limited amount of resources. Non-point source pollution from surrounding agriculture such as nutrient and pesticide rich runoff is impacting water quality and natural life both in the slough and in surrounding areas.

The Slough's Future -- Conservation Efforts: The Elkhorn Slough Tidal Wetlands Project is a program to implement strategies for conservation and restoration of the estuarine habitats in the watershed. The Parsons Slough Project aims to reduce to reduce the tidal prism in Elkhorn to minimize tidal marsh loss and habitat degradation. 
The National Estuarine research reserves host workshops, classes and field trips to educate the public about the importance of the ecosystem and our impacts

Currently over 8,000 acres of the slough, approx 18%, is under conservation protection by federal and state government. As hundreds of acres of agriculture are returned to maritime chaparral, and more land becomes protected under the federal government this ecosystem should be able to return very to it’s natural conditions.

Works Cited

"Recreation at Elkhorn Slough." Recreation at Elkhorn Slough. Elkhorn Slough Foundation. Web. 11 Dec. 2014. <http://www.elkhornslough.org/recreation/index.htm>.

"Elkhorn Slough Research : Elkhorn Slough Salt Marsh Restoration." Elkhorn Slough Research : Elkhorn Slough Salt Marsh Restoration. Elkhorn Slough Foundation. Web. 11 Dec. 2014. <http://www.elkhornslough.org/research/conserv_marsh.htm>.

"Statement of Agreement on Tidal Marsh Dieback." Elkhornslough.org. 15 Sept. 2012. Web. 11 Dec. 2014. <http://www.elkhornslough.org/research/PDF/Callaway_2012_Marsh_Dieback_Statement.pd>.f

"Major Wetlands of the World." WWF. World Wildlife Foundation. Web. 11 Dec. 2014. <http://wwf.panda.org/about_our_earth/about_freshwater/intro/majorwetlands/>.

Georgi, Carol, and Karl Kempton. "Wetlands of the California Central Coast Habitats worth Protecting with National Marine Sanctuary Designation." Slo Coast Journal. Web. 11 Dec. 2014. <http://www.slocoastjournal.com/docs/archives/2012/march/pages/marine_sanctuary.html>.

"America's Wetlands." US EPA. United States Environmental Protection Agency. Web. 11 Dec. 2014. <http://www.epa.gov/owow/wetlands/vital/wetlands.pdf>.