New Zealand Journal of Marine and Freshwater Research abstracts

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Distribution and biomass of benthic microalgae in Manukau Harbour, New Zealand

L. B. Cahoon

Department of Biological Sciences and
Center for Marine Science
UNC Wilmington
Wilmington, NC 28403
United States
email: cahoon@uncwil.edu

K. A. Safi

National Institute of Water and Atmospheric
Research Limited
P.O. Box 11 115, Hamilton
New Zealand

Abstract  Benthic microalgal biomass (as sediment chlorophyll a (Chl. a), by spectrophotometry) and taxonomic composition (by HPLC pigments analysis) were investigated at intertidal locations throughout Manukau Harbour, North Island, New Zealand. Benthic microalgal biomass averaged 97.5 mg Chl. a m^–2 for all sediment samples. Benthic microalgal biomass was higher in sediments containing at least some sand than in muddy sediments, in contrast to previous findings from Manukau Harbour. Loading of fine sediments from erosion within the harbour’s basin may, therefore, affect the amount and distribution of benthic microalgal biomass in the harbour. Average benthic microalgal biomass for the entire area of the harbour was at least 62.5 mg Chl. a m^–2. The latter value is at least 4 times higher than mean annual, spatially integrated phytoplankton biomass in Manukau Harbour, suggesting that benthic microalgae are a more important food source for estuarine consumers. High fucoxanthin:chlorophyll a ratios indicated that benthic microalgae were primarily diatoms. The physical characteristics of Manukau Harbour and similarity in taxonomic composition of the phytoplankton and benthic microalgae suggest that resuspended benthic microalgae are an important component of the harbour’s phytoplankton biomass.

Keywords  benthic microalgae; sediments; pigments; Manukau Harbour

M01057 Received 9 July 2001; accepted 4 December 2001
New Zealand Journal of Marine and Freshwater Research, 2002, Vol. 36: 257–266
0028–8330/02/3602–0257 $7.00 © The Royal Society of New Zealand 2002

PDF file of entire paper: Print-quality (123K)

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