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EFFECTS OF EUTROPHICATION ON FLORIDA ESTUARIES - Coggle Diagram
EFFECTS OF EUTROPHICATION ON FLORIDA ESTUARIES
Microbial food web
small plankton responsible for much of carbon/oxygen flux in aquatic systems
Eutrophication in estuaries and coastal zone
cultural eutrophication: increases in the supply of organic matter to an ecosystem that is fueled by anthropogenic inputs of inorganic nutrients where increases in organic matter are most often due to excess phytoplankton production
driven by increasing fertilizer use
extreme consequences of eutrophication: massive die-offs
leads to hypoxia
freshwater flow causes stratification, isolates bottom waters from atmosphere
nutrients carried with freshwater enhances algal productivity
Algal production is transported to the bottom layer via grazing or direct sinking mechanisms
Microbial respiration exceeds atmospheric resupply
cyanobacteria blooms in lakes
more nutrients: favor growth of algae
warmer temperature: favor cyanobacteria over other algae
reduce light at depth: inhibits growth of other algae
increased stratification: restricts gas exchange
effects on seagrass ecosystem: prevents photosynthesis by blocking light, resulting in total ecosystem destruction
Examples
microcystis in Lake Okeechobee
Microcystis in St Lucie Estuary
selected bloom forming eukaryotes:
Karenia brevis: marine dinoflagellate
Aureococcus and Aureoumbra--marine pelagophyte flagellates
Aureoumbra lagunensis leads to loss of seagrasses, esp in Indian River Lagoon
Heterosigma and Chattonella--marine raphidiophytes
Pseudo-nitschia--marine diatom
Pensacola Bay
fish kills during 1960s and 1970s attributed to industrial point source pollution
some seagrass has been lost
river nitrate concentrations have increased but concentrations are still relatively low
Pensacola Bay classified as Moderate-Low on eutrophication scale
is hypoxic
has large watershed relative to estuarine area
river flow affects salinity stratification
phytoplankton productivity is sensitive to seasonal flow regime
productivity at 70th percentile of estuaries worldwide
shallow
sandy shoals are sites of microphytobenthic productivity
microzooplankton play important role in grazing phytoplankton
what has been learned from studies:
high-light, warm, river dominated
often strongly stratified
low to moderate nutrient loading
modertate phytoplankton productivity that's strongly dependent on flow regine
active microzooplankton grazing that indicates a functioning/coupled microbial food web
significant benthic productivity (~20%) with relatively clear water
not in an advanced state of cultural eutrophication but would be VERY sensitive to increased nutrient loads