Coastal Ecosystems: Coastal Ecosystems: Salt Marshes and MangrovesSalt Marshes and Mangroves

Marine BiologyMarine Biology

Dr. Ouida MeierDr. Ouida Meier

Factors Driving Coastal Factors Driving Coastal EcosystemsEcosystems

LatitudeLatitude– temperaturetemperature– light, seasonalitylight, seasonality

Tidal cycles Tidal cycles – amplitude amplitude – frequencyfrequency

Wave energyWave energyDegree of riverine inputDegree of riverine input– freshwater inputfreshwater input– alluvial sediments and depositionalluvial sediments and deposition– turbidityturbidity

Factors Driving Coastal Factors Driving Coastal EcosystemsEcosystems

Geological characteristics Geological characteristics – rockrock– sandsand– sedimentsediment

Hydrological characteristics Hydrological characteristics – nearshore currentsnearshore currents– transporttransport

Continental proximity Continental proximity – nutrient inputnutrient input– anthropogenic impactsanthropogenic impacts

(cont.)

Recap: Rocky IntertidalRecap: Rocky Intertidal

Our example (Pacific Northwest): high latitude, soOur example (Pacific Northwest): high latitude, soCold Pacific waters, strong seasonalityCold Pacific waters, strong seasonalityTidal cycle: high amplitude, semi-diurnalTidal cycle: high amplitude, semi-diurnalWave energy highWave energy highFreshwater input – riverine characteristics modified Freshwater input – riverine characteristics modified by bay / estuaryby bay / estuaryGeology: rocky cliffs, interspersed w/sandy beachGeology: rocky cliffs, interspersed w/sandy beachHydrology: strong nearshore currents & transportHydrology: strong nearshore currents & transportContinental edge, input via interaction with Continental edge, input via interaction with terrestrial systemsterrestrial systems

Salt Marsh EcosystemsSalt Marsh Ecosystems

Our example (southeastern U.S.: Gulf and Atlantic Our example (southeastern U.S.: Gulf and Atlantic coasts): moderate latitude, socoasts): moderate latitude, so““Warm” Atlantic and warmer Gulf and Gulf stream Warm” Atlantic and warmer Gulf and Gulf stream waters, moderated seasonalitywaters, moderated seasonalityTidal cycle: low amplitudeTidal cycle: low amplitudeWave energy lowWave energy lowFreshwater input often critical – deltaic riverine input Freshwater input often critical – deltaic riverine input can result in extensive marsh systems, abundant can result in extensive marsh systems, abundant alluvial sediment input. Salt accumulation a challenge.alluvial sediment input. Salt accumulation a challenge.Geology: long-term alluvial sediment accumulationGeology: long-term alluvial sediment accumulationHydrology: nearshore currents & transport importantHydrology: nearshore currents & transport importantContinental edge, nutrient input via runoff, riversContinental edge, nutrient input via runoff, rivers

Salt marsh and tidal channels in coastal Georgia

Plants of the Salt Marsh Plants of the Salt Marsh CommunityCommunity

Spartina alternifloraSpartina alterniflora – marsh cordgrass – marsh cordgrass– height depends on riverine or tidal flushingheight depends on riverine or tidal flushing– export of dried mats during winter stormsexport of dried mats during winter storms– exclude salt from rootsexclude salt from roots

Salicornia – Salicornia – a succulenta succulent– Salt pansSalt pans

Fresher water and soils / higher ground: other Fresher water and soils / higher ground: other grasses (grasses (Spartina patensSpartina patens), rushes (), rushes (Juncus Juncus romerianusromerianus), sedges), sedgesZonation based on topography, inundation of Zonation based on topography, inundation of freshwater, fresh/salt fluctuation, tidal flushing, freshwater, fresh/salt fluctuation, tidal flushing, relative stresses, anoxia of soils, latitudinal gradient relative stresses, anoxia of soils, latitudinal gradient ((e.ge.g., east coast U.S.).., east coast U.S.).

Salt marsh replanted after a break in an oil pipeline

Animals of the Salt Marsh CommunityAnimals of the Salt Marsh Community

Geukensia demissa – Geukensia demissa – dominant musseldominant mussel– lives in sedimentlives in sediment– physiological variation with tidal cyclesphysiological variation with tidal cycles

Crassostrea virginicaCrassostrea virginica – oyster – oyster– dense beds in well-flushed tidal channelsdense beds in well-flushed tidal channels

Littorina irrorataLittorina irrorata – salt marsh snails; pulmonates – salt marsh snails; pulmonatesThais haemostomaThais haemostoma – oyster drill – oyster drillUca pugnaxUca pugnax, other , other UcaUca spp. – fiddler crabs spp. – fiddler crabsSesarma cinereumSesarma cinereum - marsh crabs - marsh crabs

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

An herbivore in the salt marsh community

Salt Marsh Communities:Salt Marsh Communities:

Highly productiveHighly productive

Very stressfulVery stressful

Trap sedimentTrap sediment

Stabilize and extend coastlines, especially those Stabilize and extend coastlines, especially those with fluvial inputwith fluvial input

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

Low diversity, high productivityLow diversity, high productivity

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

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

http://www.lacoast.gov/news/press/1997-10-27.htmhttp://www.lacoast.gov/news/press/1997-10-27.htmhttp://www.tulane.edu/~bfleury/envirobio/saltmarsh.htmlhttp://www.tulane.edu/~bfleury/envirobio/saltmarsh.htmlhttp://www.bonitanews.com/03/10/naples/e1631a.htmhttp://www.bonitanews.com/03/10/naples/e1631a.htm

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

Mangrove EcosystemsMangrove EcosystemsOur example (south Florida): subtropical latitude, soOur example (south Florida): subtropical latitude, so““Warm” Atlantic and warmer Gulf and Gulf stream Warm” Atlantic and warmer Gulf and Gulf stream waters, limited seasonality (moving toward rainy/dry waters, limited seasonality (moving toward rainy/dry seasons)seasons)Tidal cycle: low amplitudeTidal cycle: low amplitudeWave energy lowWave energy lowFreshwater input important – can be sheetlike Freshwater input important – can be sheetlike (Everglades) rather than distinctly riverine; alluvial (Everglades) rather than distinctly riverine; alluvial sediment input. High tannins from leaf input.sediment input. High tannins from leaf input.Geology: long-term alluvial and peat accumulationGeology: long-term alluvial and peat accumulationHydrology: more inundated than salt marshes; Hydrology: more inundated than salt marshes; nearshore currents & transport importantnearshore currents & transport importantContinental edge, nutrient input via runoff, riversContinental edge, nutrient input via runoff, rivers

Red mangroves, low tide, south Florida

Plants of the Mangrove CommunityPlants of the Mangrove Community

Rhizophora mangleRhizophora mangle – red mangrove – red mangrove– prop roots; extrudes saltprop roots; extrudes salt

Avicennia germinansAvicennia germinans – black mangrove – black mangrove– pneumatophores; extends to coastal Louisiana pneumatophores; extends to coastal Louisiana

where it, unusually, coexists w/ where it, unusually, coexists w/ SpartinaSpartina

Laguncularia racemosaLaguncularia racemosa – white mangrove – white mangrove

These have viviparous propagulesThese have viviparous propagulesMuch higher diversity in the Indo-PacificMuch 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 CommunityAnimals of the Mangrove Community

Prop roots of red mangroves provide substrate for Prop roots of red mangroves provide substrate for benthic organisms (algae, sponges, hydroids, benthic organisms (algae, sponges, hydroids, tunicates, bryozoans)tunicates, bryozoans)Mangrove swamps provide critical protected Mangrove swamps provide critical protected nursery areas for fishes, crustaceans, and nursery areas for fishes, crustaceans, and shellfish. shellfish. Dense mangrove branches serve as rookeries for Dense mangrove branches serve as rookeries for many coastal species of birdsmany coastal species of birdsOrganisms reared in mangrove swamps become Organisms reared in mangrove swamps become food for fish (snook, snapper, tarpon, jack, food for fish (snook, snapper, tarpon, jack, sheepshead, red drum) oysters, and shrimp. sheepshead, red drum) oysters, and shrimp.

Prop root communities

Wetlands Loss: Mangrove SwampsWetlands Loss: Mangrove Swamps

Many acres of mangroves in south Florida Many acres of mangroves in south Florida have been lost to development and to have been lost to development and to anthropogenic changes in hydrology.anthropogenic changes in hydrology.Globally, many areas of mangroves are Globally, many areas of mangroves are being cut for wood or converted to being cut for wood or converted to aquaculture or mariculture ponds (aquaculture or mariculture ponds (e.ge.g., ., fish, shrimp, prawns for seafood fish, shrimp, prawns for seafood restaurants).restaurants).Concomitant declines in offshore fisheries Concomitant declines in offshore fisheries can be expected and have been seen.can be expected and have been seen.

Mangrove swamp in Mexico

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