New Zealand Journal of Marine and Freshwater Research abstracts

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Responses of crustacean zooplankton to seasonal and tidal salinity changes in the coastal Lake Waihola, New Zealand

Catherine J. Hall

Department of Environmental Science and Policy
University of California, Davis
CA 95616, United States
email: cjhall@ucdavis.edu

Carolyn W. Burns*

Department of Zoology
University of Otago
P.O. Box 56
Dunedin, New Zealand
email: carolyn.burns@stonebow.otago.ac.nz
*Author for correspondence.

Abstract   Lake Waihola is a shallow, tidal, coastal lake that receives brackish inflows resulting in salinities of up to 4.8‰. We determined the importance of salinity and tidal currents on crustacean zooplankton abundance and distribution in this lake over 2 years. Tidal currents were traced using drogues, and zooplankton was sampled over tidal cycles. Tidal currents reached velocities of 35 cm s^-1 closest to the tidal inlet channel. Salinity explained 26% of the variation in the abundance and species composition of the zooplankton assemblage, and accounted for >60% of the species-environment correlation. Increases in salinity resulted in a change in crustacean dominance from the freshwater calanoid copepod, Boeckella hamata Brehm, and cladoceran, Daphnia carinata King, to the estuarine copepod, Gladioferens pectinatus Brady. The abundance of D. carinata was negatively correlated with chlorophyll a concentrations, although chlorophyll a was not correlated with salinity. Future increases in salinity and tidal currents may cause significant changes in the zooplankton community structure.

Keywords   salinity; tidal lake; Boeckella; Gladioferens; Daphnia

M02043 Received 12 June 2002; accepted 10 September 2002 ; Published 20 March 2003
New Zealand Journal of Marine and Freshwater Research, 2003, Vol. 37: 31-43
0028-8330/03/3701-0031 $7.00 © The Royal Society of New Zealand 2003

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