The problem of the island mass effect on chlorophyll and zooplankton standing crops around Mare (Loyalty Islands) and New Caledonia

The island effect on plankton biomass is tested at two different sites: Mare, a coral island directly facing the prevailing surface currents with no lagoon and no land drainage; the second site to the southwest of New Caledonia has a wide lagoon and important run-offs. Since the sole coastal chlorophyll "a" increase (<20%) is observed at the latter site and no correlation is found with vertical mixing or the thermal structure, we conclude that such an island effect is mainly due to transports from land and lagoon. Secondly, there is no relation between integrated chlorophyll "a" and zooplankton dry weights, like in most neritic ecosystems, because of the short-term variability (scale of days) of the meteorological and hydrological parameters. Finally, significant mid-term (scale of months) biomass variations are observed in this oligotrophic environment.