Seagrasses: Underwater
Food Factories
A Tampa Bay Example
of a Food Web
Producer
 Organism
that can capture energy from
sunlight or chemicals and use it to produce
food from inorganic compounds, also
called autotrophs.
 Ex- seagrasses, phytoplankton, algae,
trees
Consumer
 Organism
that relies on others for food.
 Ex- crabs, you, sharks, fish, stingrays
Decomposer
 Organism
that breaks down and obtains
energy from dead organic matter.
 Ex- bacteria, worms, crabs
 Bacteria, Fungi - Generally microscopic,
they decompose seagrass leaves
Herbivore
 Obtains
energy by eating plants.
 Ex- manatees, sea turtles
Carnivore
 Obtains
energy by eating only animals.
 Ex- sharks
Omnivore
 Obtains
energy by eating both plants and
animals.
 Ex- raccoons
Estuary
 Habitat
having a mixture of fresh and salt
water.
 Ex- Tampa Bay
Detritus
 Dead
or decaying organic matter
 Algae - Fuzzy-looking growth on seagrass
leaves. When the leaves die, the leaf and
the algae become detritus (dead or
decaying organic matter).
Seagrasses
 Underwater
flowering plants that live in
clear, shallow water.
 Ex- turtle, manatee, and shoal
Emergent
 Plants
that extend above the water.
 Ex- Saltmarsh cordgrass
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)
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.
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/coast
al/habitats/seagrass/awareness
/healthy_images.htm
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.
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.
Reasons Why Water Pollution
Would Increase

Population increased; more garbage, sewage dumped
into bay





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:



More people lived near the Bay; more workplaces built
More cars, trucks -- air pollution (mercury, NOx, lead ends up in
water)
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
Compare the Seagrass Beds
40,420 ac in 1950
26,920 ac in 1996
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.
A Big Improvement
 Improvements
in water quality have fueled
steady gains in seagrass recovery
 About
350 more acres of seagrass were
added per year, over the past decade
 The
goal is to get
to 38,000 acres
Life in a Tampa Bay Seagrass Bed
 Bacteria,
Fungi
 Algae
 Invertebrates
 Fish
 Reptiles
 Birds
 Mammals
Life in a Tampa Bay Seagrass Bed

Bacteria, Fungi


Algae






Decompose seagrass leaves
Grows on seagrass leaves, becomes detritus
Invertebrates
Fish
Reptiles
Birds
Mammals
Life in a Tampa Bay Seagrass Bed
 Bacteria,
Fungi
 Algae
– scallops, crabs
 Fish – snook, sharks
 Reptiles – sea turtles
 Birds – wading birds
 Mammals - manatees
 Invertebrates
Watch
“Seagrasses: Underwater
Food Factories”
On the Tampa Bay: Living
Legacy DVD
Your Assignment
1.
Create a color postcard describing (in pictures
and words) a food web using Tampa Bay
aquatic life. Begin with sunlight and seagrass,
and include examples of:
Bacteria/fungi
Algae
Invertebrates
Fish
Reptiles
Birds
Mammals
2.
Use the Life in a Tampa Bay Seagrass Bed info
sheet to help you.
3.
Label (or list) the producers, carnivores,
omnivores, herbivores, decomposers on your
postcard.
Your Assignment (continued)

Answer the following questions on the back of
your postcard:
1.
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.
2.
What would you expect to happen if all the
plants on your postcard died? Explain your
answer.
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