What are the Main Types of Coastal Ecosystems?

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What are the Main Types of Coastal Ecosystems?

• Estuaries and Coastal Wetlands
• Estuaries are isolated from the open sea, diluted
  by rivers (brackish water)
• Typically with low diversity but high
  productivity (abundance of certain species)
• Organisms adapted for changing salinities
  (osmoregulators, osmoconformers)
• Ecosystems include mudflats, seagrass meadows,
  salt marshes, oyster reefs, and mangroves
• Rocky Intertidal Zones
• Zonation based on exposure/desiccation,
  predation, and competition
• Splash Zone small barnacles, periwinkles, rock
  lice never submerged
• High-tide Zone larger barnacles tide pools
  (instant physical changes when tide rises,
  exposed for long periods on lowest tides of year)
• Mid-tide Zone mussels, gooseneck barnacles,
  snails and hermit crabs
• Low-tide Zone sea stars and urchins, red
  coralline algae, kelps, sea anemones
• Organisms adapted for high wave stress (spines,
  cement, suction, and burrowing) and fluctuating
  salinities (re. rain and evaporation)
• Mudflats and Beaches
• Mudflats with fine grain sizes (low wave action)
  ? more detritus, less oxygen content cohesion
  allows burrowing (ex. worms, clams) probing
  birds
• Wave-exposed beaches with larger grains ? less
  detritus and burrowing (low species diversity
  sand crabs, razor clams common)

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Figures 13-5 and 13-10
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Figures 14-12 and 14-13
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Figure 14-21b and 14-22
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Figures 14-23 and 14-24
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Where are the Worlds Coral Reefs?

• Origin and Types of Coral Reefs
• Built by Scleractinian Corals contain
  zooxanthellae dino- flagellates increased
  metabolism allows deposition of calcium
  carbonate calyx around polyp (rocky skeletons)
• Evolution of Coral Atolls (ex. Rangiroa, Bikini)
  fringing reef forms around sinking island ?
  barrier reef with channel ? atoll with lagoon
  (island consists of coral rock and sand)
• Table Reefs found in shallow areas of open ocean
• Physical Factors Limiting Reef Growth
• Zooxanthellae need clear, warm water ? no deeper
  than 60 meters and no colder than 20?C
  bleaching if too warm (zooxanthellae expelled
  from polyps)
• Sedimentation smothers corals not found near
  river mouths
• Most common around eastern side of continents
  center of coral biodiversity in Indo-Pacific
  (ex. 700 coral species in Philippines/Indonesia
  vs. 60 species in Caribbean)

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Figure 5-33
8
Figures 13-24 to 13-27
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Figure 14-27
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What are the Main Threats to the Worlds Coral
Reefs?

• The Nemesis Effect synergistic effects of
  multiple stressors (the case for most coral
  reefs)
• Global Warming bleaching occurs if water too
  warm some reefs expected to benefit (ex.
  Hawaii)
• Stratospheric Ozone Depletion increased UV light
  stresses corals and can lead to bleaching
• Overfishing including use of dynamite and
  cyanide focused efforts on sharks, Napoleon
  wrasse and bumphead parrotfish, (brain fishes)
  and seahorses
• Diseases viral and bacterial diseases noted and
  rising
• Eutrophication increased nitrogen favors growth
  of competitive macroalgae (can overgrow corals)
• Sedimentation smothers corals, reducing light
  and oxygen uptake occurs where sewage untreated

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Figure 5-35
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What are the Most Important Links in the Oceans
Biogeochemical Cycles?

• The Carbon Cycle
• Photosynthesis converts atmospheric carbon
  dioxide to sugars, which are consumed by animals
• Respiration by animals and plants plus
  decomposition by bacteria returns CO2 to
  atmosphere
• Combustion (of fossil fuels) and deforestation
  increases atmospheric CO2
• CO2 diffuses into ocean, organisms incorporate
  CaCO3 into bones, shells
• The Nitrogen Cycle
• Nitrates and nitrites absorbed by phytoplankton
  and algae, which are consumed by animals
  (nitrogen incorporated into amino acids)
• Decomposition returns nitrogenous compounds to
  water column
• Runoff from land masses and eutrophication
  increase nitrogen levels
• Coastal upwelling of deep, nutrient-rich layers
  increases nitrogen levels
• The Phosphorus Cycle and Silicon
• Short-term Cycle essentially same as nitrogen
  cycle phosphorus incorporated into DNA, ATP
  silicon into tests of diatoms
• Long-term Cycle includes incorporation in rocks
  by sedimentation and compaction uplift,
  exposure, and erosion of rocks returns phosphorus
  to the water column (over millions of years)

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Figure 6-30
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Figures 6-31 and 6-32
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Figure 14-11