In summary, bacterial growth rates sometimes showed little seasonal response in Georgia
coastal planktonic systems. Although there was a strong seasonal response in the
nearshore stations within 6 km of Sapelo Island, such a response was not evident at other
sampling sites. The absence of a strong, consistent seasonal effect on growth implies that
the populations can adapt to the seasonal temperature changes. With 1/2 the population
being replaced every 1-2 days on average (Table 2), we would expect rapid physiological
adjustements in the bacterial populations. Also, the limited annual temperature range,
7-30°C, minimizes the cost of adaptation. Bacterial growth rates are inversely related to
distance from shore, probably due to decreasing substrate availability with increasing
distance from shore. Data from the Duplin River studies indicate that some bacterial
populations may undergo classical population fluctuations because of predator and/or
substrate limitations. Planktonic bacterial production in these systems is equivalent to
only a small percentage of 14 CO2 based estimates of phytoplankton production. Further
data on the substrate inputs that actually drive the system are needed in order to better
understand the behavior of the bacterial populations in these habitats.
ACKNOWLEDGEMENTS
Funding for this work kindly provided by the Sapelo Island Research Foundation and the National Science
Foundation, Grands OCE-8214899 and -8219866. This is contribution number 535 of the University of Georgia
Marine Institute.
ARKIN H. & R.R. COLTON, 1970. Statistical methods. Barnes and Noble, Inc. 228 pp.
BELL R.T., AHLGREN G. , AHLGREN L, 1983. Estimating bacterioplankton production by measuring 3(H)thymidine incorporation in a eutrophic Swedish lake. Appl. Environ. Microbiol. 45.1709-1721.
CHALMERS A.G., R. G. WIEGERT & P.L. WOLF (In press). Carbon balance in a salt marsh: interactions of
diffusive export, tidal deposition and rainfallcaused erosion. Est. Coast. Shelf Sci.
DAIBER F.C., 1982. Animals of the tidal marsh. Van Nostrand Reinhold Co. New York, N.Y., 406 pp.
DUCLOW H.W. & D.L. KIRCHMAN, 1983. Bacterial dynamics and distribution during a spring diatom bloom in
the Hudson River Plume, USA. J. Plankt. Res. 5 : 333-355.
FALLON R.D., S.Y., NEWELL & C.S. HOPKINSON, 1983. Bacterial production in marine sediments: Will cell
specific measures agree with whole system metabolism? Mar. Ecol. Progr. Ser. 11 : 119-127.
FENCHEL T, 1982. Ecology of heterotrophic microflagellates,. IV. Quantitative occurrence and importance as
bacterial consumers. Mar. Ecol. Prog. Ser. 9 : 35-42.
FUHRMAN J.A. & F. AZAM, 1980. Bacterioplankton secondary production estimates for coastal waters of British
Columbia, Antarctica, and Calibornia. Appl. Environ. Microbiol. 39.1085-1095.
FUHRAMN A. & F. AZAM, 1982. Thymidine incorporation as a measure of heterotrophic bacterioplankton
production in marine surface waters : evaluation and field results. Mar. Biol. 66. 109-120.
FUHRMAN J.A., J. MITCHELL & J. BAUER, 1983. Bacterioplankton abundance and production in Long Island
Sound: Seasonal cycle and implications regarding grazing. Abstract N-16, Third International Symposium on
Microbial Ecology, August 7-12, 1983, Michigan State University, East Lansing, Michigan, USA.
HOBBIE J.E., R.J. DALEY & S.JASPER, 1977. Use of nuclepore filters for counting bacteria by fluorescence
microscopy. Appl. Environ. Microbiol. 33.1225-1228.
IMERGER J., T. BERMAN R.R. CHRISTIAN E.B. SHERR D.E. WHITNEY L.R. POMEROY, R.G. WIEGERT & W.J.
WIEBE, 1983. The influence of water motion on the distribution and transport of materials in a salt marsh
estuary. Limnol. Oceanogr. 28 :201-214.
144
coastal planktonic systems. Although there was a strong seasonal response in the
nearshore stations within 6 km of Sapelo Island, such a response was not evident at other
sampling sites. The absence of a strong, consistent seasonal effect on growth implies that
the populations can adapt to the seasonal temperature changes. With 1/2 the population
being replaced every 1-2 days on average (Table 2), we would expect rapid physiological
adjustements in the bacterial populations. Also, the limited annual temperature range,
7-30°C, minimizes the cost of adaptation. Bacterial growth rates are inversely related to
distance from shore, probably due to decreasing substrate availability with increasing
distance from shore. Data from the Duplin River studies indicate that some bacterial
populations may undergo classical population fluctuations because of predator and/or
substrate limitations. Planktonic bacterial production in these systems is equivalent to
only a small percentage of 14 CO2 based estimates of phytoplankton production. Further
data on the substrate inputs that actually drive the system are needed in order to better
understand the behavior of the bacterial populations in these habitats.
ACKNOWLEDGEMENTS
Funding for this work kindly provided by the Sapelo Island Research Foundation and the National Science
Foundation, Grands OCE-8214899 and -8219866. This is contribution number 535 of the University of Georgia
Marine Institute.
ARKIN H. & R.R. COLTON, 1970. Statistical methods. Barnes and Noble, Inc. 228 pp.
BELL R.T., AHLGREN G. , AHLGREN L, 1983. Estimating bacterioplankton production by measuring 3(H)thymidine incorporation in a eutrophic Swedish lake. Appl. Environ. Microbiol. 45.1709-1721.
CHALMERS A.G., R. G. WIEGERT & P.L. WOLF (In press). Carbon balance in a salt marsh: interactions of
diffusive export, tidal deposition and rainfallcaused erosion. Est. Coast. Shelf Sci.
DAIBER F.C., 1982. Animals of the tidal marsh. Van Nostrand Reinhold Co. New York, N.Y., 406 pp.
DUCLOW H.W. & D.L. KIRCHMAN, 1983. Bacterial dynamics and distribution during a spring diatom bloom in
the Hudson River Plume, USA. J. Plankt. Res. 5 : 333-355.
FALLON R.D., S.Y., NEWELL & C.S. HOPKINSON, 1983. Bacterial production in marine sediments: Will cell
specific measures agree with whole system metabolism? Mar. Ecol. Progr. Ser. 11 : 119-127.
FENCHEL T, 1982. Ecology of heterotrophic microflagellates,. IV. Quantitative occurrence and importance as
bacterial consumers. Mar. Ecol. Prog. Ser. 9 : 35-42.
FUHRMAN J.A. & F. AZAM, 1980. Bacterioplankton secondary production estimates for coastal waters of British
Columbia, Antarctica, and Calibornia. Appl. Environ. Microbiol. 39.1085-1095.
FUHRAMN A. & F. AZAM, 1982. Thymidine incorporation as a measure of heterotrophic bacterioplankton
production in marine surface waters : evaluation and field results. Mar. Biol. 66. 109-120.
FUHRMAN J.A., J. MITCHELL & J. BAUER, 1983. Bacterioplankton abundance and production in Long Island
Sound: Seasonal cycle and implications regarding grazing. Abstract N-16, Third International Symposium on
Microbial Ecology, August 7-12, 1983, Michigan State University, East Lansing, Michigan, USA.
HOBBIE J.E., R.J. DALEY & S.JASPER, 1977. Use of nuclepore filters for counting bacteria by fluorescence
microscopy. Appl. Environ. Microbiol. 33.1225-1228.
IMERGER J., T. BERMAN R.R. CHRISTIAN E.B. SHERR D.E. WHITNEY L.R. POMEROY, R.G. WIEGERT & W.J.
WIEBE, 1983. The influence of water motion on the distribution and transport of materials in a salt marsh
estuary. Limnol. Oceanogr. 28 :201-214.
144