g17 - Latitude Factors Driving Coastal Ecosystems...

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Unformatted text preview: Latitude Factors Driving Coastal Ecosystems Ecosystems – temperature – light, seasonality Tidal cycles Tidal – amplitude amplitude – frequency Wave energy Degree of riverine input – – – freshwater input alluvial sediments and deposition turbidity Geological characteristics Geological – rock – sand – sediment Factors Driving Coastal Ecosystems Ecosystems (cont.) Hydrological characteristics Hydrological – nearshore currents – transport Continental proximity Continental – nutrient input – anthropogenic impacts Recap: Rocky Intertidal Recap: Our example (Pacific Northwest): high latitude, so Cold Pacific waters, strong seasonality Tidal cycle: high amplitude, semi-diurnal Wave energy high Freshwater input – riverine characteristics modified Freshwater by bay / estuary by Geology: rocky cliffs, interspersed w/sandy beach Hydrology: strong nearshore currents & transport Continental edge, input via interaction with Continental terrestrial systems terrestrial Salt Marsh Ecosystems Salt Our example (southeastern U.S.: Gulf and Atlantic Our coasts): moderate latitude, so coasts): “Warm” Atlantic and warmer Gulf and Gulf stream Warm” waters, moderated seasonality waters, Tidal cycle: low amplitude Wave energy low Freshwater input often critical – deltaic riverine input Freshwater can result in extensive marsh systems, abundant alluvial sediment input. Salt accumulation a challenge. alluvial Geology: long-term alluvial sediment accumulation Hydrology: nearshore currents & transport important Continental edge, nutrient input via runoff, rivers Salt marsh and tidal channels in coastal Georgia Plants of the Salt Marsh Community Community Spartina alterniflora – marsh cordgrass – height depends on riverine or tidal flushing – export of dried mats during winter storms – exclude salt from roots – Salt pans Salicornia – a succulent Salicornia succulent Fresher water and soils / higher ground: other Fresher grasses (Spartina patens), rushes (Juncus grasses Juncus romerianus), sedges romerianus Zonation based on topography, inundation of Zonation freshwater, fresh/salt fluctuation, tidal flushing, relative stresses, anoxia of soils, latitudinal gradient (e.g., east coast U.S.). Salt marsh replanted after a break in an oil pipeline Animals of the Salt Marsh Community Animals Geukensia demissa – dominant mussel Geukensia dominant – 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 other Uca Sesarma cinereum - marsh crabs (These examples are particularly for south Louisiana and coastal Georgia; other species (These will occur elsewhere, filling slightly modified niches depending upon range, region, and local conditions.) and An herbivore in the salt marsh community Salt Marsh Communities: Salt Highly productive Very stressful Trap sediment Stabilize and extend coastlines, especially those Stabilize with fluvial input with Food webs detritus-based; herbivory may be Food more important than previously thought; “trophic relays” convey biomass to adjacent ecosystems Low diversity, high productivity Low Wetlands Loss: Salt Marshes Wetlands Coastal erosion and wetland loss due to channelization Coastal 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. platforms. Estimates of Louisiana coastal wetland loss for 1978-90 Estimates 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 12scrub-shrub year loss of about 420 square miles, an area twice the size year of the populated greater New Orleans area. of 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 Example of salt marsh decline in south Louisiana, http://www.brownmarsh.net Mangrove Ecosystems Mangrove Our example (south Florida): subtropical latitude, so “Warm” Atlantic and warmer Gulf and Gulf stream Warm” waters, limited seasonality (moving toward rainy/dry seasons) seasons) Tidal cycle: low amplitude Wave energy low Freshwater input important – can be sheetlike Freshwater (Everglades) rather than distinctly riverine; alluvial sediment input. High tannins from leaf input. sediment Geology: long-term alluvial and peat accumulation Hydrology: more inundated than salt marshes; Hydrology: nearshore currents & transport important nearshore Continental edge, nutrient input via runoff, rivers Red mangroves, low tide, south Florida Plants of the Mangrove Community Plants Rhizophora mangle – red mangrove – prop roots; extrudes salt Avicennia germinans – black mangrove – pneumatophores; extends to coastal Louisiana pneumatophores; where it, unusually, coexists w/ Spartina Spartina Laguncularia racemosa – white mangrove These have viviparous propagules Much higher diversity in the Indo-Pacific Zonation and Distribution of mangroves is affected by flooding, salinity, temperature fluctuations (air/soil/water), and soil. Animals of the Mangrove Community Animals Prop roots of red mangroves provide substrate for Prop benthic organisms (algae, sponges, hydroids, tunicates, bryozoans) tunicates, Mangrove swamps provide critical protected Mangrove nursery areas for fishes, crustaceans, and shellfish. Dense mangrove branches serve as rookeries for many coastal species of birds many Organisms reared in mangrove swamps become Organisms food for fish (snook, snapper, tarpon, jack, sheepshead, red drum) oysters, and shrimp. Prop root communities Wetlands Loss: Mangrove Swamps Wetlands Many acres of mangroves in south Florida Many have been lost to development and to anthropogenic changes in hydrology. anthropogenic Globally, many areas of mangroves are Globally, being cut for wood or converted to aquaculture or mariculture ponds (e.g., aquaculture ., fish, shrimp, prawns for seafood restaurants). restaurants). Concomitant declines in offshore fisheries Concomitant can be expected and have been seen. can Mangrove swamp in Mexico ...
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This note was uploaded on 02/12/2011 for the course GEO 2200 taught by Professor Wolf during the Spring '08 term at University of Florida.

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