ISSN:
1573-5117
Schlagwort(e):
blue-greens (Cyanoprokaryotes)
;
assemblages
;
productive lakes
;
Brazil
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
Notizen:
Abstract Cyanoprokaryote assemblages of eight very productive Brazilian lakes are described and the main driving forces of their dominance are considered. Relative abundance of blue-greens is shown to have been positively related to temperature, but not to pH or total-P and to have been negatively associated with light, mixing, NO3, but not with NH4, total N or total N/total P ratio. Both heterocytic and non-heterocytic groups were negatively related to NO3. However, if Cylindrospermopsis species are considered as non-N2-fixing organisms (only 10% of the filaments carried heterocytes), the lakes could be considered as dominated by non-N2-fixing populations during most of the years. In this new scenario, non-N2-fixing were dominant in NO3 (but not NH4) deficient lakes, and in both NO3 and NH4 deficient conditions. Assemblages S, S n , H, M, X 1, as groups of descriptor species of systems having similar features as proposed by Reynolds (1997: Ecology Institute, Oldenburg), were representative of warm, shallow, turbid, enriched and frequently mixed lakes. We propose to move some species from Z (picoplancton of oligotrophic lakes) to X 1 assemblage (nanoplankton of eutrophic lakes) and we comment on Microcystis species of M assemblage from mixed shallow lakes in relation to L m assemblage of end-summer in temperate lakes. S and S n assemblages, which comprise species which are good-light antennae, were the best represented group in these generally turbid and shallow lakes.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1023/A:1003996710416
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