Sea Grass Communities

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Sea Grass Communities

• Vegetated, sandy substrates
• Shallow, clear water
• Tropical and subtropical habitats
• Food webs often include large grazers
• turtles
• dugongs or manatees
• Coastal locations increase exposure to impacts
  from terrestrial land use

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Shark Bay, Australia

• Western Australia
• Isolated
• World Heritage Area
• Rare example of an intact seagrass ecosystem

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Shark Bay overview beds and channels
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Diverse algae
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Anemone in seagrass
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Mega Grazers
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Mesograzers
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Top Predator
Tiger Shark
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Predator effects
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What regulates sea grass?
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Contrast a Seagrass system near people

• e.g., southern Florida
• Near extinction of
• manatees
• large sharks
• sea turtles
• Addition of
• coastal development
• altered hydrology
• increased nutrient input

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Problems in Florida Bay seagrass
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Changes in seagrass beds
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Complexity in habitats e.g., Big Pine Key
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Complexity in distributions of organisms
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Heterogeneous communities
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Changes in local development
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Regional Patterns Sampling Levels
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Fresh water nutrient inputs increase
chlorophyll concentrations in water
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P or N nutrient limitation varies
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Dry season patterns of chlorophyll
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Wet season patterns of chlorophyll
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Larry Brand 2000 http//www.reefrelief.org/main.ht
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• An Evaluation of the Scientific Basis for
  "Restoring" Florida Bay by Increasing Freshwater
  Runoff from the Everglades
• Taken together, these data suggest that
  nutrients from Everglades-agriculture runoff are
  being transported to not just Florida Bay, but
  also the Florida Keys and coral reefs, and
  contributing to their eutrophication.