Changes in the annual harmful algal blooms of Alexandrium minutum : effects of environmental conditions and drainage basin inputs in the Rance estuary (Brittany, France)

Type Article
Date 2016-01
Language English
Author(s) Le Bec Claude1, Legendre Aurelie2, Messiaen Gregory3
Affiliation(s) 1 : IFREMER, Lab Environm Littoral & Ressources Aquacoles, Bretagne Occidentale, Pl Croix, F-29900 Concarneau, France.
2 : IFREMER, Lab Environm Littoral & Ressources Aquacoles, Bretagne Nord, F-35800 Dinard, France.
3 : IFREMER, Lab Environm Littoral & Ressources Aquacoles, Languedoc Roussillon, Ave Jean Monnet, F-34200 Sete, France.
Source Aquatic Living Resources (0990-7440) (Edp Sciences S A), 2016-01 , Vol. 29 , N. 1 , P. -
DOI 10.1051/alr/2016006
WOS© Times Cited 1
Keyword(s) Harmful algae, dinoflagellate, nutrients, eutrophication, drainage basin, land runoff
Abstract Time series of physico-chemical data and concentrations (cell L-1) of the toxic dinoflagellate Alexandrium minutum collected in the Rance macrotidal estuary (Brittany, France) were analyzed to understand the physico-chemical processes of the estuary and their relation to changes in bloom development from 1996 to 2009. The construction of the tidal power plant in the north and the presence of a lock in the south have greatly altered hydrodynamics, blocking the zone of maximum turbidity upstream, in the narrowest part of the estuary. Alexandrium minutum occurs in the middle part of the estuary. Most physical and chemical parameters of the Rance estuary are similar to those observed elsewhere in Brittany with water temperatures between 15–18 °C, slightly lowered salinities (31.8–33.1 PSU), low river flow rates upstream and significant solar radiation (8 h day-1). A notable exception is phosphate input from the drainage basin which seems to limit bloom development: in recent years, bloom decline can be significantly correlated with the decrease in phosphate input. On the other hand, the chemical processes occurring in the freshwater-saltwater interface do not seem to have an influence on these occurrences. The other hypotheses for bloom declines are discussed, including the prevalence of parasitism, but remain to be verified in further studies.
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Le Bec Claude, Legendre Aurelie, Messiaen Gregory (2016). Changes in the annual harmful algal blooms of Alexandrium minutum : effects of environmental conditions and drainage basin inputs in the Rance estuary (Brittany, France). Aquatic Living Resources, 29(1), -. Publisher's official version : https://doi.org/10.1051/alr/2016006 , Open Access version : https://archimer.ifremer.fr/doc/00341/45257/