Seagrasses: Underwater Food Factories

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Seagrasses Underwater Food Factories

• A Tampa Bay Example
• of a Food Web

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Seagrasses So What Are They?

• Seagrasses are flowering underwater plants
• Found at shallow depths in estuaries bays and
  lagoons with good water quality
• What are some reasons that these plants can grow
  only in shallow water?

Leaves
Flowers
Rhizome (underground stem)
Source http//tbep.org/portrait/habitats.html
Line drawing of Manatee grass (Syringodium
filiforme)
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They grow in shallow water because...

• Seagrasses require good water clarity and quality
  to survive.
• They possess structures similar to terrestrial
  plants like roots, leaves and flowers.
• They need sunlight to penetrate the water in
  order to perform photosynthesis.

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3 Types of Seagrasses in Tampa Bay

• turtle grass
• (yes, sea turtles eat it!)
• shoal grass
• (usually the first
• species to appear)
• manatee grass
• (yes, manatees love it!)

Pictures from http//www.dep.state.fl.us/coastal/h
abitats/seagrass/awareness/healthy_images.htm
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So, Why are Seagrass Beds Important?

• As a nursery environment, seagrasses support
  small fish, shrimp, and crabs that hide among the
  blades and feast on decaying leaves.
• They help stabilize shifting sands on the bottom
  of the bay.
• They improve water clarity by trapping fine
  sediments and particles.

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The Decline of Seagrass Beds

• After 1950, the seagrass beds in Tampa Bay
  seriously declined.
• The major reason for decline in seagrass beds is
  probably water pollution.
• As a class, list reasons why water pollution in
  Tampa Bay would increase after 1950.

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Reasons Why Water Pollution Would Increase

• Population increased more garbage, sewage dumped
  into bay
• More people lived near the Bay more workplaces
  built
• More cars, trucks -- air pollution (mercury, NOx,
  lead ends up in water)
• Oil, gasoline spills from cargo ships
• Port of Tampa receives more cargo ships (sewage,
  garbage and fuel spills from ships)
• More nitrogen entered the bay
• Sewage treatment plants were not like today
  (untreated sewage common in bay)
• Industries dumped chemically polluted waste
  directly into water
• No real government control of water pollution
  before 1972

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Compare the Seagrass Beds
40,420 ac in 1950
26,920 ac in 1996
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It Takes a Lot of People to Clean Up The Bay!

• The Tampa Bay Estuary
• Program was established in 1991.
• Group coordinates the protection and restoration
  of the bay (including seagrass beds).
• The group is a partnership consisting of
• 3 counties Hillsborough, Manatee and Pinellas
• 3 cities Tampa, St. Petersburg and Clearwater
• Government Agencies
• Southwest Florida Water Management District
• Florida Department of Environmental Protection
• U.S. Environmental Protection Agency
• Citizen groups and industries are active as well.

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A Big Improvement

• Improvements in water quality have fueled steady
  gains in seagrass recovery
• Tampa Bay is now gaining about 500 acres of
  seagrass a year, and has about 29,647 acres
  baywide as of 2008
• The goal is to get
• to 38,000 acres

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Seagrass Change Through The Years
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Tampa Bay Segments 2006 2008 Change in Acres Change
Boca Ciega Bay 8,961 8,457 -504 -6
Hillsborough Bay 415 810 395 95
Lower Tampa Bay 6,578 6,322 -256 -4
Manatee River 814 638 -176 -22
Middle Tampa Bay 5,089 6,659 1,570 31
Old Tampa Bay 5,434 5,829 395 7
Terra Ceia Bay 1,007 932 -75 -7
Tampa Bay Total 28,299 29,647 1,349 5
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Life in a Tampa Bay Seagrass Bed

• Bacteria, Fungi
• Algae
• Invertebrates
• Fish
• Reptiles
• Birds
• Mammals

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Life in a Tampa Bay Seagrass Bed

• Bacteria, Fungi
• Decompose seagrass leaves
• Algae
• Grows on seagrass leaves, becomes detritus
• Invertebrates
• Fish
• Reptiles
• Birds
• Mammals

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Life in a Tampa Bay Seagrass Bed

• Bacteria, Fungi
• Algae
• Invertebrates scallops, crabs
• Fish snook, sharks
• Reptiles sea turtles
• Birds wading birds
• Mammals - manatees

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Watch Seagrasses Underwater Food Factories

• On the Tampa Bay Living Legacy DVD

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Your Assignment

• Create a color postcard describing (in pictures
  and/or words) a food chain or web using Tampa Bay
  aquatic life. Begin with sunlight and seagrass,
  and include examples of
• Bacteria/fungi Reptiles
• Algae Birds
• Invertebrates Mammals
• Fish
• Use the Life in a Tampa Bay Seagrass Bed info
  sheet
• Label (or list) the producers, carnivores,
  omnivores, herbivores, decomposers on your
  postcard.

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Your Assignment (continued)

• Answer the following questions on the back of
  your postcard
• Fishing in Tampa Bay became less productive after
  1950 because of poor water quality. List three
  factors and explain how these factors caused poor
  water quality in Tampa Bay.
• What would you expect to happen if all the plants
  on your postcard died? Explain your answer.

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Bibliography

• Tampa Bay Estuary Program
• Http//www.TBEP.org
• Florida Keys National Marine Sanctuary
• http//Floridakeys/noaa.gov
• Florida Department of Environmental Protection
• http//www.dep.state.fl.us
• Ichthyology at the Florida Museum of Natural
  History
• http//www.flmnh.ufl.edu/fish/southflorida