Marshes

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Salt marsh replanted after a break in an oil pipeline

Slide 9

Animals of the Salt Marsh Community

Geukensia demissa – dominant mussel

lives in sediment

physiological variation with tidal cycles

Crassostrea virginica – oyster

dense beds in well-flushed tidal channels

Littorina irrorata – salt marsh snails; pulmonates

Thais haemostoma – oyster drill

Uca pugnax, other Uca spp. – fiddler crabs

Sesarma cinereum - marsh crabs

(These examples are particularly for south Louisiana and coastal Georgia; other species will occur elsewhere, filling slightly modified niches depending upon range, region, and local conditions.)

Slide 10

An herbivore in the salt marsh community

Slide 11

Salt Marsh Communities:

Highly productive

Very stressful

Trap sediment

Stabilize and extend coastlines, especially those with fluvial input

Food webs detritus-based; herbivory may be more important than previously thought; “trophic relays” convey biomass to adjacent ecosystems

Low diversity, high productivity

Slide 12

Wetlands Loss: Salt Marshes

Coastal erosion and wetland loss due to channelization and levees along the Mississippi, dams on its tributaries, land settling from groundwater pumping and use, and channels cut through the marsh for offshore drilling platforms.

Estimates of Louisiana coastal wetland loss for 1978-90 indicate a loss of about 35 square miles a year of freshwater and non-freshwater marshes and forested and scrub-shrub wetlands. From 1978-90, that equalled a 12-year loss of about 420 square miles, an area twice the size of the populated greater New Orleans area.

http://www.lacoast.gov/news/press/1997-10-27.htm

http://www.tulane.edu/~bfleury/envirobio/saltmarsh.html

http://www.bonitanews.com/03/10/naples/e1631a.htm

Slide 13

Example of salt marsh decline in south Louisiana, http://www.brownmarsh.net

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Mangrove Ecosystems

Our example (south Florida): subtropical latitude, so

“Warm” Atlantic and warmer Gulf and Gulf stream waters, limited seasonality (moving toward rainy/dry seasons)

Tidal cycle: low amplitude

Wave energy low

Freshwater input important – can be sheetlike (Everglades) rather than distinctly riverine; alluvial sediment input. High tannins from leaf input.

Geology: long-term alluvial and peat accumulation

Hydrology: more inundated than salt marshes; nearshore currents & transport important