Pelagic stocks and carbon and nitrogen uptake in a pearl farming atoll (Ahe, French Polynesia)

Type Article
Date 2021-06
Language English
Author(s) Rodier Martine1, 3, Pinazo Christel1, Seceh Claire1, Varillon David2
Affiliation(s) 1 : Aix-Marseille Université, Université de Toulon, IRD, CNRS, Mediterranean Institute of Oceanography (MIO), UM 110, 13288 Marseille, France
2 : Institut de Recherche pour le Développement, US 191 IMAGO, BP A5, 98848 Nouméa cedex, New-Caledonia, France
3 : Institut de Recherche pour le Développement, UMR 241 EIO (Université de la Polynésie française, IRD, ILM, Ifremer), B.P. 6570, 98702 Faa'a, Tahiti, French Polynesia
Source Marine Pollution Bulletin (0025-326X) (Elsevier BV), 2021-06 , Vol. 167 , P. 112352 (11p.)
DOI 10.1016/j.marpolbul.2021.112352
WOS© Times Cited 5
Keyword(s) Nitrogen uptake, Primary production, Phytoplankton composition, Atoll lagoon, Pearl farming, French Polynesia

This study reports the first measurements of nitrogen uptake and new data on carbon fixation (15N/13C incorporation) for two size-fractionated phytoplankton (<2 μm and >2 μm), on organic matter, and phytoplankton stocks in Ahe lagoon. Data were collected between November and December 2017, during the hot season with prevailing trade winds. Ammonium and nitrate uptake data (7.58 to 39.81 and 1.80 to 21.43 μmol N m−3 h−1, respectively) suggest a rapid turn-over of N-nutrients in the water column and show that primary production was largely sustained by recycled nitrogen providing 68% of the pelagic N demand. These results highlight the spatial heterogeneity of the measured processes linked to the local hydrodynamics, exhibiting higher regenerated production in the more exploited southwestern part of the lagoon and a higher proportion of new production in the north. Intense nutrient recycling appears to promote nanophytoplankton production which is critical for pearl oyster growth.

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