Issue |
Aquat. Living Resour.
Volume 29, Number 1, January-March 2016
|
|
---|---|---|
Article Number | 104 | |
Number of page(s) | 13 | |
DOI | https://doi.org/10.1051/alr/2016006 | |
Published online | 23 May 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)
1 IFREMER, Laboratoire Environnement
littoral et Ressources aquacoles, Bretagne Occidentale, Place de la Croix, 29900
Concarneau,
France
2 IFREMER, Laboratoire Environnement
littoral et Ressources aquacoles, Bretagne Nord, rue Port Blanc, 35800
Dinard,
France
3 IFREMER, Laboratoire Environnement
littoral et Ressources aquacoles, Languedoc-Roussillon, av. Jean Monnet, 34200
Sète,
France
a Corresponding author:
clebec@ifremer.fr
Received:
22
April
2015
Accepted:
28
January
2016
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.
Key words: Harmful algae / dinoflagellate / nutrients / eutrophication / drainage basin / land runoff
© EDP Sciences 2016
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.