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The development of epilithic cyanobacteria communities in a Mediterranean calcareous stream in the province of Murcia (SE Spain) was studied during the course of one year in an attempt to clarify the environmental variables that influence the production of microcystins. The predominant cyanobacteria were species of Rivularia, which formed conspicuous(More)
The aquatic plant communities of the irrigation channels of the Transvase Tajo-Segura project are described in order to assess the various options for the control of nuisance vegetation. The low flow rate permits relatively complex planktonic assemblages in addition to epipelic cyanophytes, diatoms and chlorophyes. The only macrophytes to establish(More)
The seasonal sampling of irrigation or drinking water reservoirs in the province of Murcia (SE Spain) in the hydrological year 2000-2001 revealed the presence of intracellular microcystins in the benthic cyanophyte communities throughout the year. The total microcystin levels, as measured by HPLC, were relatively high but lower than others published for(More)
There is increasing evidence that benthic cyanophytes in Mediterraneancalcareous streams can influence the macroinvertebrate community, probablydirectly due to toxicity. A study was therefore planned to establish whetherthis also influenced the results of indices used for the biological monitoringof stream water quality. Two indices (BMWPc based on(More)
The effects of multiple stressors on marine diatom assemblages are still poorly understood. The interactive effects of metals and nutrients were assessed in two coastal biofilms grown at a reference site and a historically contaminated site. The biofilms were exposed in situ to pulse exposures of metals (Zn and Pb) and nutrients (N and P) individually and(More)
In this study, we demonstrate the inhibitory effect of both cyanobacterial extracts and pure microcystins on the growth of microalgae and bacteria. This inhibitory effect was more persistent in pure microcystins than in the extracts, which lost their properties eight days after exposure. In addition, the effects on bacteria were longerlasting than those on(More)
One of the most striking features of the diatom Didymosphenia geminata, which has increased markedly in abundance in a number of countries in recent years, is the very large branched stalks. In order to help understanding their role, an ultrastructural study was carried out on two populations, one from a stream in northern England and the other from a river(More)
Forty-one heterocystous cyanobacteria strains representing 12 cyanobacterial genera collected from all across India were assessed in phylogenetic and evolutionary perspectives. The structural gene 16S ribosomal RNA (rRNA) and the functional genes nifD and psbA were selected as molecular chronometers in this study. The phylogenetic analyses demonstrated the(More)
Although Mediterranean marshes have historically suffered high anthropogenic pressure, they have maintained their remarkable biodiversity. They are severely threatened but remain comparatively unexplored systems from the algological point of view. For example, most of the indexes proposed for monitoring ecological quality are based on diatoms and very few(More)
The ecological influence of cyanotoxins on aquatic biota remains unclear despite the numerous published references on toxicological and sanitary problems related with cyanophyte proliferation. The effects of microcystins and cyanophyte extracts on the photosynthesis of the algae that belong to two taxonomic groups, Rhodophyta and Bacillariophyta, were(More)