Pheopigment dynamics, zooplankton grazing rates and the autumnal ammonium peak in a Mediterranean lagoon

Type Article
Date 2005-11
Language English
Author(s) Collos Yves1, Husseini Ratrema Julie1, Bec Béatrice1, Vaquer André1, Hoai Thong Lam1, Rougier Claude1, Pons Virginie1, Souchu Philippe2
Affiliation(s) 1 : Univ Montpellier 2, UMR 5119, CNRS, Montpellier 5, France.
2 : IFREMER, Lab Cotier DEL, F-34203 Sete, France.
Source Hydrobiologia (0018-8158) (Kluwer), 2005-11 , Vol. 550 , N. 1 , P. 83-93
DOI 10.1007/s10750-005-4365-1
WOS© Times Cited 30
Keyword(s) Zooplankton, Ammonium, Pheopigments, Degradation, Growth, Phytoplankton
Abstract The dilution technique was used to estimate chlorophyll and pheopigment, net and gross production as well as zooplankton grazing over a 12-month period in a coastal lagoon in Southern France. Chlorophyll a (Cha) based gross growth rates of phytoplankton ranged from undetectable in February to 2.6 day(-1) in June, corresponding to 3.8 divisions per day. Cha-based grazing rates ranged from undetectable in February to 1.1 d(-1) in June. The seasonal growth pattern of picoplankton was similar to that of the whole community, with a peak in July, corresponding to four divisions per day. Grazing processes represented from 20 to 150% of the phytoplankton daily growth, and the grazing pressure was stronger on small phytoplankton cells than on larger cells. Gross growth rates of phytoplankton were related to zooplankton grazing rates, and both were related to water temperature. Mesozooplankton which escaped sampling or oysters had to be also invoked as additional sinks for the primary production. In the fall, pheopigment concentrations greater than chlorophyll concentrations coincided with high ammonium levels in the water column. Pheopigment a production rates were highly correlated to chlorophyll -based microzooplankton grazing rates. The pheopigment a to chlorophyll a ratio was correlated with aminonium concentrations and could be used an index of the balance between ammonium supply (degradation) and demand (uptake by phytoplankton). In addition, pheopigment degradation rates in absence of grazing could be related to irradiance, indicating photo-degradation of these compounds.
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Collos Yves, Husseini Ratrema Julie, Bec Béatrice, Vaquer André, Hoai Thong Lam, Rougier Claude, Pons Virginie, Souchu Philippe (2005). Pheopigment dynamics, zooplankton grazing rates and the autumnal ammonium peak in a Mediterranean lagoon. Hydrobiologia, 550(1), 83-93. Publisher's official version : https://doi.org/10.1007/s10750-005-4365-1 , Open Access version : https://archimer.ifremer.fr/doc/00000/727/