Autotrophic and heterotrophic abundance and activity associated with a nearshore front off the Georgia coast,U.S.A. |
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| Authors: | TR Jacobsen LR Pomeroy JO Blanton |
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| Institution: | 1. Institute of Ecology, The University of Georgia, Athens, GA 30602, U.S.A.;2. Skidaway Institute of Oceanography, P.O. Box 13687, Savannah, GA 31406, U.S.A. |
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| Abstract: | The nearshore frontal zone off the coast of Georgia was found to be an area of high phytoplankton and bacterioplankton abundance and activity. Phytoplankton and bacterioplankton populations on the seaward side of the frontal zone had significantly higher photosynthetic and heterotrophic potentials than the nearshore side of the front. Phytoplankton species composition changed across the front, verifying that the front is a barrier to cross shelf mixing. Nearshore, large chain forming diatoms dominated, while smaller single cell diatoms and cyanobacteria dominated the seaward side of the front. Increased bacterioplankton activity was found associated with phytoplankton photosynthetic activity. Light appeared to be the major factor controlling photosynthesis across the frontal zone. Nitrogen, phosphorus and silica were present in similar concentrations, well above levels that would limit photosynthesis, on both sides of the front. Therefore the outflow of nutrients from rivers or estuaries did not influence primary production directly. |
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| Keywords: | microbial activity bacteria phytoplankton fronts Georgia Coast |
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