Here are some good websites for what the climate change could possibly do to currents and coastal zones.  I'm still writing up the summary and will post it when I'm done.

 How the currents will change:

 http://www.whoi.edu/page.do?pid=12455&tid=282&cid=9986

Affect on the Gulf coast: 

 http://www.usgcrp.gov/usgcrp/nacc/gulfcoastworkshop.htm#chapter5\\

Summary:

1. most of the climate change scenarios predict increased variability in temperature at the regional level.
2. Warming projections are based on annualized temperature changes
3. Increased variability in precipitation -->potential to greatly impact coastal fisheries by
   • affecting freshwater inflow to estuaries--> affecting flushing rates (the location of the freshwater- saltwater interface
   • the quality of coastal estuarine nursery areas for fish and shellfish.
4. Inland: increased variability in precipitation has the potential to negatively impact riverine fish  resources.
5. Gulf Coast
   • small rates of sea-level rise take on a special significance in coastal Louisiana
   •  Fishermen of the Terrebonne Fishermen's Organization expressed concern about coastal erosion  and the loss of coastal marsh habitat.
   • subsidence of delta deposits of the Mississippi River and human alteration of coastal marsh.
   •  fishermen, who depend on the marsh for their livelihood, are concerned that sea level changes  will exacerbate the current problems of coastal erosion.
   • past 20 years (research): many of the estuary dependent species (including the important coastal  fishery species) tend to use only the edges of marsh surrounding the estuary (only the first 50-150  ft).
   • Computer simulations suggest that changes in fishery production in Louisiana can be correlated  with changes in the amount of marsh edge.
     •  any change in fishery-dependent habitat, from regional climate or sea level change, that  affects the quantity or quality of marsh edge has the potential to greatly impact fishery  production.

1. • Coastal marsh is disappearing at an alarming rate in Louisiana (25-35 square miles per year).
   • believed that global climate changes will have little impact on offshore fisheries (e.g., epipelagic  species such as tuna and mackerel, and bottom-oriented species such as snapper) because of their  mobility and the less seasonal nature of offshore habitats.

--> the larval stages of many of these species develop in nearshore areas and are dependent  on Gulf currents for dispersal.

1. • aquatic organisms have particular ranges of physiological tolerance to factors such as  temperature, salinity, pH, and dissolved oxygen.
     • species are found only in habitats that meet all of their requirements for survival, growth,  and reproduction.

1. • A change to warmer water temperature in the Gulf of Mexico--> potential to shift the zone of  inhabitance of tropically adapted species northward
   • zone of inhabitance of more temperately adapted species will be restricted because northward  movement in the Northern Gulf of Mexico is limited by the coastline.
   • The ability of species to migrate north or south is dependent on the range of stream sizes the  species normally inhabits, and the presence of barriers to dispersal such as dams or natural  physiographic features.
   • Other stresses include:
     • Habitat loss due to factors such as subsidence, saltwater intrusion, and coastal  development;
     • Habitat fragmentation that results in barriers to dispersal and genetic migration;
     • Modification of freshwater inputs due to effects of dams and/or levees on timing of release  of water, sediment, and nutrients to coastal habitats;
     • Pollution; and
     • Overexploitation of fishery resources.
       

Climate change or variability stresses in the following ways:

1. • results in redistribution of coastal marsh --> exacerbate habitat loss and fragmentation because of  the increasingly disturbed nature of the coastal zone
   • increase in severe weather-->potential to increase freshwater input (with positive or negative  impacts depending on timing and location), and damage barrier islands with negative impacts on  marsh and therefore coastal fisheries
   • Temperature variability--> potential to either negatively or positively impact remaining fish stocks,  depending on the timing (season, habitat, and life history stage affected).
     
     
     
     
     
     

 
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