Spatio-temporal variation in density of microphytoplankton genera in two tropical coral reefs of Mauritius

  • SB Sadally
  • N Taleb-Hossenkhan
  • R Bhagooli

Abstract

Spatial and temporal (seasonal and interannual) variation in microphytoplankton was investigated at two tropical coral reef sites off Mauritius (Belle Mare [BM] and Flic-en-Flac [FEF]), from 2010 to 2012. Each site was divided into three zones: coast, lagoon and reef. Microphytoplankton, nutrient and chlorophyll a samples were collected, and physico-chemical parameters were measured in situ. A total of 56 microphytoplankton genera were identified (43 diatoms, 8 dinoflagellates and 5 cyanobacteria). Total microphytoplankton density exhibited spatial and temporal variation, being higher at BM and near the coast, and mostly high in summer. Nutrient concentrations were highest near the coast as a result of run-off events and anthropogenic inputs, especially during heavy rainfall, and this resulted in elevated total microphytoplankton density. There were no clear diversity patterns at the two sites or within the different zones. At both sites, Navicula, Cocconeis and Fragilaria were the dominant diatoms, and Gymnodinium, Alexandrium and Protoperidinium were the dominant dinoflagellates. There was a shift in dominance from Navicula in summer to Fragilaria in winter. This seasonal shift may reflect how these species respond differently to environmental change, which could have implications for primary production at spatial and temporal scales.

Keywords: chlorophyll a, cyanobacteria, diatoms, dinoflagellates, interannual variation, physico-chemical, seasonal variation

African Journal of Marine Science 2014, 36(4): 423–438

Author Biographies

SB Sadally
Department of Biosciences, Faculty of Science, University of Mauritius, Réduit, Mauritius
N Taleb-Hossenkhan
Department of Biosciences, Faculty of Science, University of Mauritius, Réduit, Mauritius
R Bhagooli
Department of Marine and Ocean Science, Fisheries and Mariculture, Faculty of Ocean Studies, University of Mauritius, Réduit, Mauritius
Published
2015-04-01
Section
Articles

Journal Identifiers


eISSN: 1814-2338
print ISSN: 1814-232X