What are Seagrasses and Why are they Important? |
Seagrass meadows are an essential component of the marine ecosystem. Seagrasses perform vital ecological functions such as primary production, stabilizing sediments, increasing habitat complexity and diversity. They act as nursery grounds for fish and
invertebrates, maintain water quality, act as contaminant sinks, and form the basis of the marine detrital food web, as well as being directly consumed by marine herbivores like manatees and green turtles. Why be Concerned about Habitat
Protection For Manatees? A viable population of manatees will not persist without suitable habitat. Florida’s increasing human population, and particularly the associated coastal development, is a long-term threat to the manatee’s habitat.
Historically, coastal development has resulted in degradation of
water quality
and destruction of seagrasses—the manatee’s primary food. Ways to minimize negative effects of
coastal development are being explored. The first step is to better understand the manatee’s habitat needs and to monitor and assess habitat health and stability. The health of any habitat is important as an indicator of that
habitat’s ability to sustain a viable population of manatees and other marine species.
What are some of the Impacts to Seagrasses in Florida? Damage to seagrass communities, which result from accidental grounding and propeller strikes from watercraft, has been recognized as an environmental problem by scientists and natural
resource managers since the 1970s. Propeller scars are the result of mechanical excavation of seagrass plants, including the below ground root/rhizome complex, when struck by the propeller and associated engine or steering structures of a watercraft operated in water shallower than the
required operational draft of the boat. Damage of this nature can take from between 3-7 years to recover under good conditions, but may be permanent and lead to further seagrass damage in areas with fast moving currents, such as can be found around channels and inlets. Propeller scarring is
presumed to result from negligent operation of propeller driven watercraft or operation of such craft with ignorance of navigation rules and markers in shallow waters.
Seagrass Protection Efforts |
In the late 1980s, environmental managers from federal wildlife refuges, Florida State parks and aquatic preserves, and county natural resource divisions began addressing the loss of marine and estuarine habitat associated with propeller scarring of seagrass
systems. Surveys of badly scarred seagrass resources within managed areas under these authorities resulted in recommendations ranging from creation of focused public education programs to the implementation of no entry zones to protect seagrass communities.
Boating restriction zones protecting seagrass from propeller scarring have been in place in Florida waters since 1990, when Lee County first adopted, although never enforced, regulations stipulating that motor powered
vessels could not enter identified areas in local waters. Since that time, eleven other zones varying from combustion engine operation exclusion zones to zones stipulating no entry of any kind have been established around the state in Pinellas, Hillsborough, Sarasota, Monroe, Dade and Brevard
Counties.
Interagency
Manatee
Habitat
Working
Groups
(updated
7/7/04)
Habitat
staff
works
with
various
groups
around
the state
on
manatee
habitat
issues.
The Blue
Spring
Working
Group is
one such
group
that
meets at
Blue
Spring
State
Park each
year.
The
average
annual
flow of
Blue
Spring
has been
reduced
by 5%
when
compared
to the
historic
average
annual
flow.
Consumptive
pumping
of
aquifer
water
within
the
spring
basin can
reduce
spring
flow by
between
5-7% at
currently
permitted
capacity.
Although
climatic
conditions
affect
spring
flows
greatly,
human use
of the
aquifer
water
supplied
to this
spring
has
reduced
the warm
water
habitat
available
to
manatees
and other
wildlife
using the
spring
run.
Human
population
growth
within
the
spring
basin is
anticipated,
and
increasing
demands
on
consumptive
use of
aquifer
water is
reflected
in
proposed
regional
20 year
municipal
water use
plans.
The
working
group
addresses
issues
like this
because
the
withdrawal
levels
could
reduce
spring
flows to
levels
that
would not
provide
the
volume of
warm
water
necessary
to
support
the large
numbers
of
manatees
using the
Blue
Spring.
Related Links:
Fish and
Wildlife Research Institute: Habitat Assessment and Restoration
Florida International University Seagrass Ecosystems Research Lab University of Florida Center for Aquatic and
Invasive Plant Southeastern Estuarine Research Society
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