In the Everglades, periphyton
and floc form the base of the food web.
Small fish, shrimp and other organisms eat this stuff. In turn, large fish and birds
feed on small fish and shrimp, and alligators and other top predators feast on large
fish and birds. Each of the players in this food web is both directly and indirectly
affected by the amount of nutrients and water in the ecosystem. Such trophic dynamics
are of particular interest to FCE-LTER scientists.
In Phase II of the FCE-LTER project, researchers are investigating
nutrient transport, which they expect contributes substantially to ecological
processes in the nutrient-poor ecotones.
They are also examining the effects of
increased freshwater flow and organic matter
on consumers and food webs. Increased
freshwater flow and expected increases of floc may
modify animal-mediated nutrient transport if consumers change their movement patterns
or habitat use in response to changes in surface water conditions, such as salinity
and flow rates, or biotic factors, such as prey availability and predator abundance.
Researchers are using acoustic telemetry to track four species - Florida gar, snook,
American alligators, and bull sharks -
in order to quantify their movements; they are using drop-trap and throw-trap
sampling to determine fish species
composition and biomass; and they are measuring
nutrients in fish tissues.
How do these factors affect people in south Florida?
The large consumers, like fishes, are the reason that many
people visit the Everglades. Knowing what determines the distribution of these
animals will help people to enjoy the ecosystem and help managers ensure that
it remains a wonderful recreational area for generations to come.
Joel Trexler using a throw trap to sample fish communities
Sampling fish communities using a throw trap