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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
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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)
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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
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WHAT CAN HAPPEN to cause habitat destruction
- Filling and construction
- Diking
- Building breakwaters and marinas
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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
- 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
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DIKING
- 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
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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
- DREDING AND DITCHING
- 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
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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
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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
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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
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