Metazooplankton communities in the Ahe atoll lagoon (Tuamotu Archipelago, French Polynesia): Spatiotemporal variations and trophic relationships

Abstract

Metazooplankton abundance, biomass (<80 μm, 200-500 μm and >500 μm) and community structure in the Ahe atoll were studied together with their relationships with environmental factors (temperature, salinity, wind) and trophic factors (phytoplankton, bacteria, heterotrophic nanoflagellates (HNF) and ciliates) during three periods in 2008-2009. Meroplankton, mainly bivalve and gastropod larvae, was dominant. Holoplankton was dominated by copepods, the main species being Oithona spp., Paracalanus parvus, Clausocalanus spp., Corycaeus spp., Acartia fossae and Undinula vulgaris. The results suggest a clear wind influence on the structure and horizontal distribution of the zooplankton communities. The metazooplankton appeared to be controlled mainly by food resources, suggesting a bottom-up control. The low nanophytoplankton biomass in contrast to the high abundance of picophytoplankton, HNF and nano-particle grazers (mainly Oithona spp., Paracalanus and bivalve larvae) highlighted the importance of the microbial loop in the food web.

Influence of plankton concentration on gametogenesis and spawning of the black lip pearl oyster Pinctada margaritifera in Ahe atoll lagoon (Tuamotu archipelago, French polynesia)

“…Previous studies in French Polynesian atolls have shown that plankton concentration variations can be significant at small spatial and/or temporal scale, despite the average low concentrations and the weak seasonal differences (Buestel and Pouvreau, 2000;Charpy et al, 2012;Fournier et al, 2012, González et al, 1998Pagano et al, 2012;Sournia and Ricard, 1976;Thomas et al, 2010). However, the exact mechanisms responsible for these changes remain unclear.…”

Pearl oysters Pinctada margaritifera grazing on natural plankton in Ahe atoll lagoon (Tuamotu archipelago, French Polynesia)

“…These observations are unusual in Tuamotu atoll lagoons where the biomass of >2 lm planktonic particles is approximately 36% of the total planktonic biomass, as reviewed by Pouvreau et al (2000a). Previous studies in French Polynesian atolls have shown that plankton concentration variations can be significant at small spatial and/or temporal scale, despite the average low concentration of plankton and despite weak seasonal trends (Buestel and Pouvreau, 2000;Charpy et al, 2012;Fournier et al, 2012;González et al, 1998;Pagano et al, 2012;Sournia and Ricard, 1976;Thomas et al, 2010). However, the exact mechanisms responsible for these changes remain unclear.…”

“…Despite their average low abundance, transitory peaks of diatoms, bivalve larvae and other metazoan larvae concentration have been observed in atoll lagoons Pagano et al, 2012;Sournia and Ricard, 1976). These plankton fractions may therefore represent significant food sources for pearl oysters.…”

Spatio-temporal diversity of free-living and particle-attached prokaryotes in the tropical lagoon of Ahe atoll (Tuamotu Archipelago) and its surrounding oceanic waters

“…This leads subsequently to an increase in bacterial production and a stimulation of the microbial loop and impacts the higher trophic levels of the food web (Ferrier- Pages and Gattuso, 1998). In Ahe atoll, the microbial loop has been described as predominant (Pagano et al, 2012) and the community as heterotrophic. This finding is supported by spatio-temporal pervasiveness found in this study for heterotrophic groups such as Marinovum, Flavobacteria and Erytrobacter.…”