During the expedition by the research vessel Tyro to study the effect of the monsoons on the coastal ecosystems and adjacent areas in the Western Indian Ocean, a taxonomic list was prepared of all the microphytoplankton species recorded along four transects during the Southeast monsoon in the period covering June 18 to July 7, 1992. A total of 235 taxa were recorded in 52 stations. Canonical correspondence analysis was performed on the data set. There was a large difference between the sum of all unconstrained eigenvalues and the sum of all canonical eigenvalues indicating that probably some important environmental variables could have been overlooked. The Monte Carlo test for significance found the p-value of the first canonical axis to be significant (0.04) in explaining the species distribution along this axis, associated with temperature, nitrate and silicate. The environmental variables considered were probably too few to explain fully the spatial distribution of such a large number of microphytoplankton species. However a relatively distinct thermocline population could be distinguished as having some positive association with increasing values of nitrate and silicate. |
