Estuaries
Maia P. McGuire, PhD
Marine Extension Agent
What is an Estuary?
A partially enclosed body of water
formed where fresh water from
rivers and streams mixes with salty
water from the ocean.
Why are estuaries
important?
They are very productive ecosystems
which provide habitats for wildlife
• To find shelter
• To find food
• As breeding grounds
Salt marsh
Mangroves
Oyster bars
Mud flats
Beach and open water
Horseshoe
crab
Blue crab
Fiddler crab
White shrimp
Striped hermit
crab
Jellyfish &
comb jellies
Moon snail
Ribbed mussel
Marsh
periwinkle
Crown
conch
Spinner
Bonnethead
Scalloped hammerhead
Butterfly
ray
Stingray
How do estuaries benefit
humans?
Estuaries provide:
• Water filtration
• Flood control
• Recreational enjoyment
• Water filtration
Water draining off the uplands through
salt marsh has much of the sediment and
nutrients filtered out. This filtration
process creates cleaner and clearer
water.
• Flood control:
Wetlands absorb
flood waters and
dissipate storm
surges.
• Recreational enjoyment:
People love estuaries for their beauty
and for fishing, swimming, boating,
diving, wildlife viewing, hunting,
learning, and working.
Human Impacts on Coastal
Environments
• Accidental and deliberate actions
Introduced/exotic species
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Ballast water
Release of aquarium specimens
Deliberate introduction of plants
Introduction of plants by birds etc.
Problems with exotics
• Direct competition with local
species
– Native species may be displaced
• Habitat modification
• Health impacts on wildlife and
humans
Examples of introduced
species
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Some red tide algae
Brazilian pepper
Walking catfish
Zebra mussel
Green mussels
Lionfish
Habitat modification
• Alteration of water flow patterns
– Agricultural use
– Residential/drinking water use
– Flood control
• Filling of wetlands for construction and
pest control (mosquito)
• As human population grows, so does
stress on coastal areas
Local population growth
• As percent increase from 1990-2000
– Nassau County— 31%
– Duval County—16%
– St. Johns County—47%
– Flagler County—74%
– Florida average—24%
Wetland losses
• Almost 60% of Florida’s
freshwater marshlands
have been destroyed
since 1936 (mostly in the
Kissimmee-Everglades
region)
• About 30% of the
remaining natural areas in
Florida (upland and
wetland) are protected
Physical alteration of
wetlands
• Filling for construction
– Alters drainage patterns
– Removes habitats
– May isolate wetland areas
– May introduce sediment into coastal
areas
Chemical alteration of
wetland areas
• Misuse/overapplication of
fertilizers
• Use of wetland areas as biofilters
• Acid rain
• Runoff from urban/agricultural
areas
– Pesticides
– Petroleum
Point-source vs. non pointsource pollution
Oil pollution
• 51% of oil entering the oceans
comes from runoff
– 5% is from big spills
– 19% is from routine maintenance
– 2% is from offshore drilling
– 13% is from burning fuels (e.g. car
exhaust)
– 10% is from natural seeps
Trash in the coastal
environment
• The typical American discards 5 lbs of
garbage per day
–
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40% is paper
17.5% is yard waste
8.5% is metals
8% is plastic
7% is glass
 Duval county = 311,000 lbs of plastic
per day
Plastics
Fishing line/rope/nets
Balloons/plastic
bags
Bottles/containers
Is It All Hopeless?
…what you can do to help protect
the coastal environment
At home
• Pay attention to labels and what
you put down the drain
– Dispose of hazardous materials
properly
– Call the county solid waste
department if you are unsure how
to dispose of something safely
• In the garden
– Read and follow instructions on
fertilizers and pesticides; use natural
methods as much as possible
– Use mulch to reduce the need to
water
– Use native, drought-tolerant plants
– Use sprinklers conservatively
• When working on the car
– Most fluids that come out of the
car are hazardous—take them to a
recycling center (auto shop)
– Repair leaks promptly
– Do not wash oil/gas/antifreeze
into the street—absorb spills using
kitty litter or special oil absorbing
pads
• Know the environment
When boating
– Don’t run aground/avoid shallow water
– Observe speed limits and no wake zones
• Fuel responsibly
– Don’t overfill—spilled gas will go straight into the
estuary
– Don’t discharge bilge water into the estuary
unless you have an oil-absorbing product in your
bilge
• Dispose of wastes properly
– Collect garbage on the boat and dispose of it
when you return to shore
– Use pumpouts
•Clean your boat responsibly
–Use small amounts of biodegradable
soap or use natural cleaners
–Don’t let paint chips get into the water
When fishing
• Don’t leave monofilament
fishing line in the environment
– Cut it into small pieces and put it
in the garbage
– Look for monofilament recycling
stations
Do your part
• When visiting coastal areas, pick up
garbage that you see, especially
plastics
• Participate in organized cleanup
events/volunteer
• Try to avoid trampling vegetated areas
(dunes, saltmarsh)
• Don’t feed wild birds/animals
• Educate others