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Bioaccumulation du méthylmercure chez les invertébrés aquatiques aux latitudes tempérées et polaires : rôle des facteurs écologiques, biologiques et géochimiques
| Content Provider | Semantic Scholar |
|---|---|
| Author | Chételat, John |
| Copyright Year | 2009 |
| Abstract | Mercury is a contaminant of concem in polar regions due to long-range atmospheric transport of this metal from southem latitudes followed by intense deposition on snow. We surveyed zooplankton in 16 lakes and ponds in the Canadian Arctic Archipelago (74-76°N) to determine their methy1mercury (MeHg) concentrations and the role of environmental characteristics and taxonomic composition on accumulation processes. Zooplankton communities containing Daphnia (mainly D. middendorffiana) had on average 5 times the MeHg concentration of copepod-dominated communities. The percent biomass of Daphnia best explained MeHg variation in bulk zooplankton compared to water chemistry and morphometric variables. Water-column concentrations of MeHg were low at most study sites (mainly S; 0.07 ng LoI), and Daphnia strongly bioaccumulated mercury through species-specific processes. Since we observed Daphnia in more productive water bodies (i.e., ponds, a eutrophied lake), we then tested the ro1e of productivity in determining the distribution of this keystone herbivore using a broad-scale literature data set of 47 High Arctic lakes (65-77°N). Daphnia density was positively related to the amount of organic carbon in the water-column in both dissolved and particulate fractions (DOC partial R2adj= 0.39,p < 0.001; POC partial R2adj= 0.05,p == 0.032). The strong influence of DOC suggests that bacterial production is an important energy source for Arctic Daphnia. Our findings indicate that productivity influences the MeHg concentration of zooplankton communities through its control of species composition; specifically, low productivity limits the presence of mercury-ri ch Daphnia in many copepod-dominated lakes of the High Arctic. Aquatic productivity is expected to increase with c1imate warming, and we present a conceptual model that predicts how |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://papyrus.bib.umontreal.ca/xmlui/bitstream/handle/1866/6595/Chetelat_John_2009_these.pdf?isAllowed=y&sequence=1 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
