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1979
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Michel Ricard et al., « Le plancton du lagon de Takapoto », Journal de la Société des Océanistes, ID : 10.3406/jso.1979.2992
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Le plancton du lagon de Takapoto. The plankton of the Takapoto lagoon has been investigated and the collected data made it possible to point out some peculiarities which underline the specificity of this ecosystem. PHYTOPLANKTON : in spite of the stability of the nutritive and physical conditions of the lagoon, the distribution of the phytoplankton biomass is heterogeneous. The chlorophyll a concentrations range from 0.07 to 0.84 mg/m3 and are characterized by a very distinct vertical stratification and a very variable horizontal repartition. The biomass is more important during the southern summer than during the winter. Qualitatively, diatoms predominate with the number of taxa but dinoflagellates are the most numerous. ZOOPLANKTON : during the day the zooplankton of the lagoon predominates in the deep layers but, at sunset, there is a quick twilight superficial maximum which results from the rising of the deep plankton. As for the phytoplankton, the distribution of the zooplankton is heterogeneous and it seems to be, partly, determined by winds. Only a few species constitute the essential of the biomass: the main constituants are chaetognaths and copepods for holoplankton, crustacean larvae, mollusc larvae and fish-eggs for meroplankton. The zooplankton of the lagoon is most abundant at the end of spring and during the southern summer. The Takapoto lagoon appears to be a virtually closed ecosystem where great autonomy is possible owing to particular mechanisms : acceleration of mineralisation processes, quick turnover, shortenings of the food-chain.