Environmental factors affecting methyl mercury accumulation in zooplankton

Westcott, Kim; Kalff, Jacob

doi:10.1139/f96-178

Cited by 62 publications

(26 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In forest harvested and fire-impacted lakes, MeHg concentrations varied from 35 to 240 ng g −1 dry mass and from 17 to 377 ng g −1 dry mass, respectively. These ranges were comparable to those observed in other freshwater systems (Westcott & Kalff, 1996;Watras et al 1998;Gorski, Cleckner, Hurley, Sierszen, & Armstrong, 2003;Kainz & Mazunder, 2005).…”

Section: Mehg Concentrations In Bulk Zooplanktonsupporting

confidence: 90%

Seasonal and Inter-Annual Variations in Methyl Mercury Concentrations in Zooplankton from Boreal Lakes Impacted by Deforestation or Natural Forest Fires

Garcia

Carignan

Lean

2006

Environ Monit Assess

View full text Add to dashboard Cite

We compared the effects of natural and anthropogenic watershed disturbances on methyl mercury (MeHg) concentration in bulk zooplankton from boreal Shield lakes. MeHg in zooplankton was monitored for three years in nine lakes impacted by deforestation, in nine lakes impacted by wildfire, and in twenty lakes with undisturbed catchments. Lakes were sampled during spring, mid- and late summer. MeHg in zooplankton showed a seasonal trend: concentrations were the lowest in spring, then peaked in mid-summer and decreased in late summer. Over the three study years, MeHg concentrations observed in mid-summer in zooplankton from forest harvested lakes were significantly higher than in reference and fire-impacted lakes, whereas differences between these two groups of lakes were not significant. The pattern of distribution of MeHg in zooplankton during the different seasons paralleled that of dissolved organic carbon (DOC), which is known as a vector of Hg from watershed soils to lake water. Besides DOC, MeHg in zooplankton also showed a positive significant correlation with epilimnetic temperature and sulfate concentrations. An inter-annual decreasing trend in MeHg was observed in zooplankton from reference and fire-impacted lakes. In forest harvested lakes, however, MeHg concentrations remained higher and nearly constant over three years following the impact. Overall these results indicate that the MeHg pulse observed in zooplankton following deforestation by harvesting is relatively long-lived, and may have repercussions to the accumulation of MeHg along the food chain. Therefore, potential effects of deforestation on the Hg contamination of fish should be taken into account in forest management practices.

show abstract

Section: Mehg Concentrations In Bulk Zooplanktonsupporting

confidence: 90%

Seasonal and Inter-Annual Variations in Methyl Mercury Concentrations in Zooplankton from Boreal Lakes Impacted by Deforestation or Natural Forest Fires

Garcia

Carignan

Lean

2006

Environ Monit Assess

View full text Add to dashboard Cite

show abstract

“…We also found significantly lower hepatic Hg levels in lemon sharks acutely exposed to HABs (Table 1). Negative relationships between Hg tissue levels and eutrophic indices have been reported in aquatic biota, including phytoplankton (Pickhardt et al 2002), zooplankton (Westcott and Kalff 1996), invertebrate (Rudd and Turner 1983), and various freshwater fish species (Rudd and Turner 1983;Wren and Maccrimmon 1983;Essington and Houser 2003;Allen et al 2005) and may be explained by the concept of bloom dilution (Pickhardt et al 2002) and a realization that Hg turnover in the liver is relatively high. With increasing algal biomass during a bloom event, the concentration of Hg per cell decreases.…”

Section: Resultsmentioning

confidence: 99%

Mercury and selenium levels in lemon sharks (Negaprion brevirostris) in relation to a harmful red tide event

Nam

Adams

Reyier

et al. 2010

Environ Monit Assess

View full text Add to dashboard Cite

Tissue levels of mercury (Hg; total, organic) and selenium (Se) were assessed in juvenile lemon sharks (Negaprion brevirostris) from Florida nearshore waters collected during a harmful algal bloom (HAB, brevetoxin) event and compared with sharks not exposed to HABs. In all sharks studied, total Hg levels in the muscle were generally present in a molar excess over Se (which may protect against Hg toxicity) and mean muscle Hg levels (0.34 microg/g) exceed safe human consumption guidelines. While there was generally no difference in tissue Hg and Se levels following exposure of sharks to HABs, hepatic Hg levels were significantly lower (56% reduction) in the HAB-exposed sharks compared to controls. As Hg and HABs are globally increasing in scope and magnitude, further work is warranted to assess their interactions and biotic impacts within aquatic ecosystems, especially for a species such as the lemon shark that is classified as a near-threatened species by the International Union for the Conservation of Nature.

show abstract

“…The percentage of wetland area within a catchment has been positively correlated with levels of CH 3 Hg + in downstream waters, suggesting that wetlands export this form of Hg to lakes and rivers (St. Louis et al, 1994;Hurley et al, 1995;Rudd, 1995). Percentage wetland area is also positively correlated to concentrations of THg in fish and to CH 3 Hg + in invertebrates and zooplankton (Westcott and Kalff, 1996;Chasar et al, 2009). Factors that influence the gain or loss of wetlands can therefore be important in determining the amount of CH 3 Hg + in downstream receiving environments and its uptake into food webs.…”

Section: Watershed Characteristics and Human Activitiesmentioning

confidence: 99%