habitat destruction

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habitat destruction
2011-10-05 17:02:41
habitat destruction

habitat destruction
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  1. Habitat destruction
    • More of a problem in quiet sandy or muddy areas
    • Human activities cause alterations of an area and badly affect the Fauna
    • Cumulative effect:
    • Multiple activities contribute to problems, especially if in small area
    • 1 person builds here-not much of a problem, but then another builds 1mi away and another etc
    • White point sewer outfall-drains LA toliets-nutrient rich
  2. There is lack of knowledge of BENEFITS of marshes, bays, sand flats etc to human beings
    • Human uses: fisheries (crabs, shrimps, fishes, fur) and nursery areas; Wildlife watching
    • Sea grass and marshes are good for juveniles
    • Storm protection
    • If more marshland, Louisiana wouldn't have been as affected and levis might not have broken
    • Marsh hay
    • Feeding area for many animals ie sea turtles (at one point)
  3. WHY does habitat destruction occur
    • Add to property taxes
    • Marshes don't pay taxes, condominiums do
    • LACK of appreciation of Value
    • Think of it as mosquito breeding ground
    • People use it as dump site
    • No beautiful coral reefs etc
    • Most there is burrowed down and small
  4. WHAT CAN HAPPEN to cause habitat destruction
    • Filling and construction
    • Diking
    • Building breakwaters and marinas
  5. Problems caused by filling/ contruction
    • Concrete, dirt and fill just dumped on top of mud or sand
    • Compaction-pressure pushed on sand /mud causes:
    • Subsidence=sinking
    • Can cause cracking in building, major dips in highways
    • Serious developer uses pilings
    • Pilling-supports heavily anchored and go way down into sand
    • Less subsidence
    • Totally destroys the marsh
    • Dike-building large barrier of earth to prevent waterflow
    • Prevents hurricane surge
    • Can get 8ft surge during hurricane
    • Vs typical 2ft tide
    • Building a dike: pile up dirt but make triangle so wave goes up and then slides back down
    • New Orleans-were cheap so they just put dirt around concrete column
    • Storm washed base away=> collapse
    • Older ones are often more stable and strong-built to last
  7. Problems with dikes
    • Water doesn't flow past dike=> marsh area closer inland can dry or have HYPERSALINE water=> lots die and can't live there
    • Creating channels for boats
    • Can disrupt natural flow in marsh
    • Natural channel meanders
    • Have areas where sediment accumulates and doesn't accumulate
    • Artificial channels are straight
    • Can cause erosion of marsh
    • Can cave in
    • Boat wakes-water kicked up behind it
    • The waves can cause additional erosion=>cave in
  8. Building marinas and breakwaters
    • Deflect flow of water
    • LA vs longbeach
    • Areas that were once deep become shallow
    • Deep dredged channels
    • Often stratified
    • Diffusion lacking, no gas exchange=>stratification
    • Build up at bottom, become stagnant
    • Fall storms=> mixes water=overturn
    • OVERTURN-acidic mess from bottom brought to surface by fall storm
  9. Marina problems
    • no water flow become very anaerobic=>No fish
    • Human activity can cause siltation=>bury local species , prevent feeding and /or respiration
    • If mud goes over sand=> no more gas exchange=>revent algae etc in water from being washed over shrimp clams etc to eat
    • Not dumping anything on top of it, just create tons of silt
  10. RESTORATION of habitats
    • Can it be done-Maybe
    • Mitigation-developer does something to provide equal habitat to that lost or damaged by activities
    • Replanting sea grasses, spartina, mangroves
    • Works sometimes ,but other not
    • Sediment may have been changed due to human activity
    • Doesn't have to work, just have to show effort
    • Takes years after restoring to establish
    • Often enough, damage is enough that need major hurricane or earthquake to bring it back to where it was