Data/hora: 05/06/2024 16:05:45

Provedor de dados: 	5	
País: 	France	
Título: 	Seasonal succession of cyanoprokaryotes in a hypereutrophic oligo-mesohaline lagoon from the South of France	
Autores: 	Chomerat, Nicolas; Garnier, Robert; Bertrand, Céline; Cazaubon, Arlette.	
Data: 	2007-05	
Ano: 	2007	
Palavras-chave: 	Turbid state; Pseudanabaena limnetica; Planktothrix agardhii; Phytoplankton; Mediterranean area; Cyanoprokaryotes; Ecology; Lagoon; Brackish water.	
Resumo: 	The Bolmon lagoon (South of France) is an oligo-mesohaline coastal lagoon that has undergone intense eutrophication in the past decades, resulting from a strong concentration of human activities in its drainage basin. Consequently, it exhibits some characteristics typical of an advanced trophic state; namely, the disappearance of submerged vegetation, the permanently intense phytoplankton growth and the recurrence of cyanoprokaryote blooms. As cyanoprokaryote dominance in south-temperate saline lagoons is little reported, we carried out this study in order to understand the seasonal variations in the phytoplankton composition and biomass, and to analyse the influence of environmental parameters such as salinity, nutrients and climate on the seasonal succession of species. In this lagoon, the phytoplankton was permanently dominated by cyanoprokaryotes, probably because of high availability of nutrients, low light penetration in the water column and frequent turbulent mixing induced by wind. The two most abundant species Planktothrix agardhii (in winter-spring) and Pseudanabaena limnetica (in summer) have low light requirements and are well adapted to a high mixing frequency, which defines the S I functional group in Reynolds' typology for phytoplankton. Although widely studied in north-temperate lakes, blooms of these typically freshwater species are almost unreported in the Mediterranean area, especially in brackish ecosystems that are not their normal habitat. In the Bolmon lagoon, all their requirements for nutrients, light and mixing are satisfied and they seem to cope with a moderate presence of salt but P. agardhii was less competitive than P. limnetica at highest salinities, the latter being probably more halophytic. Contrary to the observations in lakes located at higher latitudes, the Mediterranean climate seems to induce a typical seasonal pattern of succession characterised by the dominance of P. agardhii (winter) - Chroococcales (spring) - Pseudanabaenaceae (summer) - P. agardhii (autumn, winter). The warm temperatures seemed to have a major influence on the phytoplankton succession, being responsible for the survival of Planktothrix during winter and its rapid and intense development in early spring. Intense mixing and high irradiance in summer promoted the development of Pseudanabaenaceae, as reported in another south-temperate lagoon, the Albufera of Valencia (Spain). The ecological success of Oscillatoriales observed in the Bolmon lagoon is a perfect example of a shift to the "turbid stable state" as proposed for freshwater shallow lakes only. Our work demonstrated that hypereutrophic Mediterranean lagoons can function very similarly to shallow lakes at higher latitudes; but the warmer climate and higher irradiances are probably responsible for differences in the seasonal pattern of species dominance. (c) 2006 Elsevier Ltd. All rights reserved.	
Tipo: 	Text	
Idioma: 	Inglês	
Identificador: 	http://archimer.ifremer.fr/doc/2007/publication-2593.pdf

DOI:10.1016/j.ecss.2006.11.008	
Editor: 	Elsevier	
Relação: 	http://archimer.ifremer.fr/doc/00000/2593/	
Formato: 	application/pdf	
Fonte: 	Estuarine, Coastal and Shelf Science (0272-7714) (Elsevier), 2007-05 , Vol. 72 , N. 4 , P. 591-602	
Fonte: 	2006 Elsevier Ltd All rights reserved