La matière particulaire des eaux du lagon de Takapoto: nourriture potentielle pour les élevages d’huı̂tres perlières

Abstract

Particulate matter in Takapoto lagoon waters: potential food for cultivated pearl oysters. Results of research concerning the food of the pearl oyster Pinctada margaritifera are presented, by taking Takapoto atoll (Tuamotu archipelago, French Polynesia) as a study site. Monthly sampling of several parameters representative of bivalve environment and food (water temperature, salinity, mineral and organic matter, proteins, lipids and carbohydrates, chlorophyll a and phaeopigments) confirm and increase knowledge of the Takapoto lagoon hydrobiology. The variability of these parameters was analysed. Takapoto lagoon showed a remarkable spatial stability. Temporal variations showed a low seasonal trend. Local meteorology (wind, precipitation) had an influence on short-term variability (especially for mineral matter). Night and day rhythm also affected some parameters (temperature, chlorophyll a, lipids and carbohydrates). In this shellfish environment, carrying capacity appears to be low: organic matter is around 0.35 mg·L −1, chlorophyll a concentration is below 0.30 μg·L −1 and energetic content of particulate material in waters, approx. 2 J·L −1, is ten times lower than in temperate areas. On the other hand, seasonal effect is reduced and particulate food is always available. Preliminary results on carrying capacity show that cultivated pearl oysters play an insignificant role on the system in comparison with the natural trophic bivalve population. © 2000 Ifremer / CNRS / IRD / Éditions scientifiques et médicales Elsevier SAS Pinctada margaritifera / suspended matter / carrying capacity / pearl oyster / atoll