A management focused investigation into phytoplankton blooms in a sub-tropical Australian estuary
Keywords:
algal blooms, primary production, flushing times, zooplanktonAbstract
Tidal flushing, primary production and phytoplankton and zooplankton communities were investigated to establish the processes leading to persistently high levels of phytoplankton (in excess of 15 to 60 μg l−1 chlorophyll a) in a particular reach of Berowra Estuary, a relatively large drowned river valley estuary in New South Wales, Australia. Residence times at the bloom site were sufficiently long to provide an opportunity for exponential growth of algae and to result in large accumulations of cells and high rates of primary production. Phytoplankton taxa over the study period were dominated by various diatoms, Chaetoceros, Pseudonitzschia, Thalassiosira and Skeletonema. Zooplankton biomass (wet weight of taxa between 90 and 900 μ m equivalent circular diameter), estimated using image analysis technology was significantly greater in the bloom area (200 mg m−3), than upstream (140 mg m−3) and downstream (120 mg m−3) sites. Numbers of individuals in the smallest zooplankton size classes were significantly related to chlorophyll a concentrations. The relationship decreased with increases in the particle size classes, showing an uncoupling between chlorophyll a concentrations and abundance of larger zooplankton. Residence times in the bloom reach were sufficient for secondary production (somatic and egg production) to occur in the zooplankton taxa present. Growth of phytoplankton under the conditions of nutrients, light and temperature exceeded losses due to zooplankton grazing and estuarine flushing, maintaining chlorophyll concentrations of more than 10 μ g·l−1.
References
Beisner, B. E., Mccauley, E. and Wrona, F. J. 1997. The influence of temperature and food chain length on plankton predator-prey dynamics. Can. J. Fish. Aquat. Sci., 54: 586–595. [CSA]
Cattani, O. and Corni, M. G. The role of zooplankton in eutrophication, with special reference to the Northern Adriatic Sea. Proceedings of an International Conference. March 21–24 1990, Bologne, Italy. Marine Coastal Eutrophication, Edited by: Vollenweider, R. A., Marchetti, R. and Viviani, R. pp.137–158. Amsterdam: Elsevier.
Chisholm, L. A. and Roff, J. C. 1990. Abundances, growth rates and production of tropical neritic copepods off Kingston. Jamaica. Mar. Biol., 106: 79–89. [CROSSREF][CSA]
Geider, R. J., Macintyre, H. L. and Kana, T. M. 1997. Dynamic model of phytoplankton growth and acclimation: Responses of the balanced growth rate and the chlorophyll a: carbon ratio to light, nutrient limitation and temperature. Mar. Ecol. Prog. Ser., 148: 187–200. [CSA]
Goldman, J. C., McCarthy, J. J. and Peavey, D. C. 1979. Growth rate influence on the chemical composition of phytoplankton in oceanic waters. Nature, 279: 210–215. [CROSSREF][CSA]
Harding, L. W. and Perry, E. S. 1997. Long term increase of phytoplankton biomass in Chesapeake Bay, 1950–1994. Mar. Ecol. Prog. Ser., 157: 39–52. [CSA]
Johnson, L. 1996. Berowra Creek. A review of environmental issues for management, Australia: NSW. Unpublished Report for Hornsby Shire Council
Lund, J. W., Kipling, C. and Le Cren, E. D. 1958. An inverted microscope method of estimating algal numbers and the statistical basis of estimations by counting. Hydrobiologia, 11: 143–170. [CROSSREF][CSA]
Malone, T. C., Conley, D. J., Fisher, T. R., Gilbert, P. M., Harding, L. W. and Sellner, T. G. 1996. Scales of nutrient-limited phytoplankton productivity in Chesapeake Bay. Estuaries, 19: 371–385. [CROSSREF][CSA]
Manly Hydraulics Laboratory. 1997. “Berowra Creek tidal data collection May to November 1995”. NSW Department of Public Works and Services. Report MHL 745,
Rissik, D., Suthers, I. M. and Taggart, C. T. 1997. Enhanced zooplankton abundance in the lee of an isolated reef in the south Coral Sea: The role of flow disturbance. J. Plankt. Res., 19: 1347–1368. [CSA]
Roelke, D. L., Cifuentes, L. A. and Eldridge, P. M. 1997. Nutrient and phytoplankton dynamics in the sewage impacted Gulf coast estuary: Field test of the PEG model and equilibrium resource competition theory. Estuaries, 20: 725–742. [CROSSREF][CSA]
Sprules, W. G., Casselman, J. M. and Shuter, B. J. 1983. Size distribution of pelagic particles in lakes. Can. J. Fish. Aquat. Sci., 40: 1761–1769. [CSA]
Strickland, J. D. H. and Parsons, T. R. 1972. A practical handbook of seawater analysis. Bull. Fish. Res. Bd. Canada, 167 Ottawa, ON[CSA]
Thompson, P. A. 1998. Spatial and temporal patterns of factors influencing phytoplankton in a salt wedge estuary, the Swan river, Western Australia. Estuaries, 21: 801–817. [CROSSREF][CSA]
Uye, S. and Sano, K. 1998. Seasonal variations in biomass, growth rate and production rate of the small cyclopoid copepod Oithona davisae in a temperate eutrophic inlet. Mar. Ecol. Prog. Ser., 163: 37–44. [CSA]
van Senden, D., Rissik, D. and Fisher, I. 1998. Berowra Creek Estuary Processes Study. Estuarine Water Quality, NSW Department of Public Works. MHL Report 928
Vollenweider, R. A. 1971. “Methods for measuring production rates”. In Primary Production in Aquatic Environments, Edited by: Vollenweider, R. A. 41–126. Oxford: Blackwell Scientific Publications.
Webber, M. K. and Roff, J. C. 1995. Annual biomass and production of the oceanic copepod community off Discovery Bay, Jamaica. Mar. Biol., 123: 481–495. [CROSSREF][CSA]
Published
Issue
Section
License
Manuscripts must be original. They must not be published or be under consideration for publication elsewhere, in whole or in part. It is required that the lead author of accepted papers complete and sign the MSU Press AEHM Author Publishing Agreement and provide it to the publisher upon acceptance.
