Loading...
Please wait, while we are loading the content...
Similar Documents
Réponse de la communauté de mollusques aux perturbations physiques et chimiques dans un grand lac fluvial (Lac Saint-Pierre, Fleuve Saint-Laurent, QC)
| Content Provider | Semantic Scholar |
|---|---|
| Author | Genovese, Amélie |
| Copyright Year | 2015 |
| Abstract | Les mollusques sont des indicateurs de perturbations anthropiques et environnementales. Ce groupe de macroinvertebres represente en outre une source importante de nourriture pour les poissons et les oiseaux aquatiques du littoral. Les hypotheses de cette etude sont que la communaute de mollusques est influencee indirectement par les tributaires agricoles et/ou par des variables environnementales (comme la dessiccation et l'exposition aux vagues) puisque ces perturbations sont susceptibles de modifier leurs sources alimentaires et leur habitat. Les indicateurs de la reponse des mollusques aux agents perturbateurs sont la composition, la diversite, la densite, ainsi que la biomasse des especes. En septembre 2013, des mesures de parametres physico-chimiques de l'eau ont ete realisees, et des echantillons de mollusques et de vegetation aquatique ont ete preleves a 14 sites le long des rives du lac Saint-Pierre (Fleuve Saint-Laurent, Quebec, Canada). Le long de la rive nord, les sites fortement exposes a l'action du vent, situes a de plus grandes elevations, affichaient une plus faible densite, biomasse et richesse specifique de mollusques que les sites de la rive sud, en milieu plus abrite et profond. Les sites physiquement perturbes etaient caracterises par de faibles biomasses en macrophytes submerges. Les sphaeriidae apparaissent comme des exceptions a ces patrons, montrant une abondance plus elevee aux sites presque depourvus de macrophytes. Bien que les variables physiques et l'habitat exercent une influence determinante sur les communautes de mollusques, les gasteropodes et les moules unionides etaient egalement affectes par la degradation de la qualite de l'eau dans le panache des tributaires agricoles. La richesse, la densite et la biomasse des gasteropodes etaient negativement influencees par des teneurs elevees de matieres en suspension et de fer dissous. Les resultats de notre etude montrent que la communaute de mollusques du lac Saint-Pierre est directement affectee par l'emersion periodique, l'exposition au vent, et indirectement par l'effet de ces variables physiques sur les macrophytes qui constituent leur habitat. Molluscs are indicators of anthropogenic and environmental disturbances and constitute an important food source for littoral fish and aquatic birds. The main hypotheses put forward for our study are that the mollusc community is impacted by the agricultural tributaries and/or by physical variables (desiccation, exposure to waves) through changes in food and habitat. The indicators used were mollusc species composition, diversity, density, and biomass. Over the course of two weeks in September 2013, we sampled physical/chemical water variables, collected aquatic vegetation and molluscs at 14 sites on both shores of Lake Saint-Pierre (St. Lawrence River, Quebec, Canada). Sites located at higher elevations, subjected to recent water level fluctuations, and exposed to wind fetch along the north shore, had lower gastropod and unionid mussel richness, density, and biomass than less-exposed sites located at lower elevations along the south shore. These physically disturbed sites were characterized by low biomasses of submerged macrophytes. Sphaerid clams appeared to be notable exceptions to these patterns, showing their highest abundances at sites almost devoid of macrophytes. In spite of the fact that physical and habitat variables exerted a strong effect on mollusc communities, gastropod and unionid mussels were additionally affected by degraded water quality originating from agricultural tributaries. Gastropod richness, density, and biomass were negatively influenced by high levels of total suspended matter and dissolved iron. Our results show that the mollusc community in Lake Saint-Pierre was primarily affected by the direct influence of periodic emersion, wind exposure, and indirectly through the effect of these physical variables on macrophyte habitat. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://belsp.uqtr.ca/1032/1/Genovese_2015_Mollusques_peturbations_physiques%20_chimique.pdf |
| Alternate Webpage(s) | https://papyrus.bib.umontreal.ca/xmlui/bitstream/handle/1866/12501/Genovese_Amelie_2015_Memoire.pdf?isAllowed=y&sequence=4 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
