Spatial and temporal dynamics of size-structured photosynthetic parameters (PAM) and primary production (13C) of pico- and nano-phytoplankton in an atoll lagoon

Physical and chemical control of the phytoplankton of Ahe lagoon, French Polynesia

“…This estimation is within the range of values obtained in Ahe using 13 C uptake (Lefebvre et al, 2012), in Tikehau and Takapoto (Charpy, 1996) and in the SW lagoon of New Caledonia (Torreton et al, 2010) using 14 C uptake.…”

“…We consider that extracted Chl a gives a more reliable measure of phytoplankton biomass, and the in vivo gradient observed by Thomas et al (2010) may be due to an increase in fluorescence with depth rather than any real biomass increase. In our case, the homogeneous distribution of Chl a indicates no photoinhibition in the upper layer in agreement with Lefebvre et al (2012) and could be explained (1) by low nutrient inputs from the benthic system at the sedimentwater interface as measured by Gaertner-Mazouni et al (2012):…”

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

“…In October 2008 and February 2009 during high wind speed condition from the east (7-9 m s À1 ), the observed little difference between stations may be the consequence of water homogenization by the overturning lagoon-scale current that may affect in the same way the depth sampled here (0-10, and 0-20 m depending on stations). In May, the clear spatial differences of chlorophyll and autotrophic organisms between central (stations 3 and 9) and coastal (stations 1 and 11) stations may be partly explained by lighter winds (<2-4 m s À1 ) stronger pass influence, and by the difference in residence time between the atoll sectors, as suggested by Lefebvre et al (2012). The effect of wind on biological properties was already shown by Charpy and Charpy-Roubaud (1991) and Torréton et al (2007).…”

“…4). A large part of this variability may be linked to water circulation within the lagoon and with the exchanges with the ocean, as discussed by Lefebvre et al (2012) for photosynthetic parameters. Dumas et al (2012), using one year field data and a 3D hydrodynamic model, showed how the wind influences the water circulation in Ahe atoll.…”

Influence of farmed pearl oysters and associated biofouling communities on nutrient regeneration in lagoons of French Polynesia

“…The theoretical nutrient requirement for primary production was calculated assuming that phytoplankton uptake of dissolved inorganic nutrients was within the Redfield ratio for growth (Redfield et al 1963). Based on primary production presented by Lefebvre et al (2012) . With an estimated density of 40 pearl oysters per square meter at the farmed site, colonized ropes would thus supply around 70% of the nitrogen requirement for primary production, whereas cleaned pearl oysters would supply only 26%.…”