Benthic diatom assemblages as indicators of water quality in the Everglades and three tropical karstic wetlands

Epilithic diatoms were sampled at 48 sites along the St. Lawrence River, from Salaberry de Valleyfield to Québec City, in an attempt to determine how diatom assemblages were related to measured water quality variables. Canonical correspondence analysis was used to explore the relationships between environmental variables and patterns in the epilithic diatom assemblages. "Distance downstream from Cornwall" was determined to be the strongest variable influencing the structure of epilithic diatom assemblages, likely due to the effect of tides (favouring aerophilic species) closer to the river outlet. Variables related to pollution (suspended solids, fecal coliforms, chlorophyll a) also explained significant (P < 0.05) amounts of variance in the diatom assemblages. The optima of common diatom species to suspended solids were explored further. Reconstructive models using weighted-averaging calibration and regression illustrated that "distance from Cornwall" and concentrations of suspended solids, fecal coliforms, and chlorophyll a, the most influential variables, could be inferred from the diatom assemblages. When compared with the inference models developed for pollution variables using epiphytic diatom assemblages (attached to macrophytes or Cladophora), the epilithon model appears to perform better.Key words: diatoms, rocks, epilithic, St. Lawrence River, water quality, calibration.

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Water quality assessment of benthic diatom communities for water quality in the subalpine karstic lakes of Jiuzhaigou, a world heritage site in China

Journal of Mountain Science ◽

10.1007/s11629-014-3392-7 ◽

2016 ◽

Vol 13 (9) ◽

pp. 1632-1644 ◽

Cited By ~ 3

Author(s):

Li-li Ouyang ◽

Yang-dong Pan ◽

Cheng-min Huang ◽

Ya Tang ◽

Jie Du ◽

...

Keyword(s):

Water Quality ◽

Quality Assessment ◽

Water Quality Assessment ◽

World Heritage ◽

Benthic Diatom ◽

World Heritage Site ◽

Heritage Site ◽

Karstic Lakes ◽

Diatom Communities

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Effects of Didymosphenia geminata blooms on benthic diatom assemblages in the Restigouche River Watershed, eastern Canada

Botany ◽

10.1139/cjb-2014-0216 ◽

2015 ◽

Vol 93 (5) ◽

pp. 317-323 ◽

Cited By ~ 4

Author(s):

Branaavan Sivarajah ◽

Joshua Kurek ◽

Kathleen M. Rühland ◽

John P. Smol

Keyword(s):

Benthic Diatom ◽

Diatom Assemblage ◽

Diatom Assemblages ◽

Eastern Canada ◽

Didymosphenia Geminata ◽

Assemblage Composition ◽

River Watershed ◽

And Function ◽

Riverine Systems ◽

The Impact

Nuisance Didymosphenia geminata (Lyngbye) M. Schmidt (didymo) blooms were first reported in 2006 from the Restigouche River Watershed (RRW), eastern Canada. Although government agencies and recreational users are concerned about these blooms, little is known about the impact on biota and (or) the structure and function of the relatively pristine riverine systems of the RRW. Here, we assess whether didymo blooms affect overall benthic diatom assemblage composition by examining epilithic samples from middle stretches of the Patapedia and Upsalquitch rivers. Significant (albeit minor) differences (P < 0.05) in diatom assemblage composition between sites, with and without didymo blooms, were only observed from the Patapedia River. Rarefied diatom species diversity (Hill’s N2) and rarefied richness did not differ significantly among sites, regardless of the presence or absence of blooms. Our data show that didymo blooms have minimal effect on benthic diatom assemblage composition in the RRW.

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Penicillin-mediated changes in viable benthic diatom assemblages – insights about the relevance of bacteria across spatial and seasonal scales

Marine and Freshwater Research ◽

10.1071/mf13083 ◽

2014 ◽

Vol 65 (5) ◽

pp. 437 ◽

Cited By ~ 1

Author(s):

Priya M. D'Costa ◽

Arga C. Anil

Keyword(s):

Ecological Study ◽

Benthic Diatom ◽

Diatom Assemblages ◽

Total Inhibition ◽

Mesocosm Experiments ◽

Lactam Antibiotic ◽

Intertidal Sandflat ◽

Penicillin Treatment ◽

Conditioning Film ◽

Limited Diffusion

Penicillin, a β-lactam antibiotic, cannot affect diatoms directly but does so through bacteria. Its effects on viable benthic diatom assemblages in a tropical environment were evaluated across spatial (intertidal sandflat, mangrove site, port environment) and seasonal (post-monsoon, pre-monsoon, monsoon) scales. Penicillin treatment resulted in bacterial suppression and a reduction in diatoms at the intertidal and mangrove sites having stable pennate-dominated assemblages. Diatom response at the port site, dominated by transient centric diatoms, ranged from total inhibition to enhancement. The monsoon diatom assemblages, which differed in composition from those in other seasons, showed reduced susceptibility to penicillin. These observations highlight the bacterial influence on diatom assemblages and the significance of species composition of diatom assemblages in these interactions. Epipsammic diatoms (Cocconeis, Grammatophora and Thalassionema) were more sensitive to penicillin than epipelic forms, probably due to: (1) their inability to escape unfavourable bacterial metabolites because of limited diffusion in benthic environments; and (2) the interference of penicillin with the bacterial ‘conditioning’ film required for their attachment. Overall, the observations from the present, preliminary, ecological study provide insights into the relevance of bacteria in influencing viable benthic diatom assemblages across spatial and seasonal scales and emphasise the need for future mesocosm experiments on these aspects.

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