Methyl mercury concentrations in macroinvertebrates and fish from burned and undisturbed lakes on the Boreal Plain

Allen, Erik W.; Prepas, E. E.; Gabos, Stephan; Strachan, William M. J.; Zhang, Weiping

doi:10.1139/f05-103

Cited by 40 publications

(51 citation statements)

References 33 publications

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“…We hypothesize that fire characteristics (i.e., fire severity, proportion of catchment burned, and timing and intensity of runoff) influence limiting nutrient and contaminant release from burned catchments, altering the relative importance of the two Hg accumulation mechanisms. This hypothesis provides an explanation for the differing results from studies conducted in severely and/or fully burned catchments (19,43,44). The postfire changes in Hg cycling observed in this study are likely not unique to Moab Lake.…”

Section: Resultsmentioning

confidence: 59%

“…Fire-mobilized nutrients (usually N and sometimes P) (16) can enhance lake productivity (17). Forest fire also has been shown to cause small increases in ␦ 15 N of aquatic organisms (17)(18)(19), which some attributed to increased inputs of inorganic nitrogen from the catchment (18,19), not food web alterations. Few have studied the effects of forest fire on the biogeochemical cycling of Hg.…”

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confidence: 99%

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Forest fire increases mercury accumulation by fishes via food web restructuring and increased mercury inputs

Kelly

Schindler

Louis

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

133

121

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Recent findings indicate that fishes from lakes in partially burned catchments contain greater mercury (Hg) concentrations than fishes from reference catchments. Increased methyl Hg (MeHg) concentrations in fishes can result in serious health problems for consumers. Here we show that a forest fire caused a 5-fold increase in whole-body Hg accumulation by rainbow trout (Oncorhynchus mykiss) and smaller Hg increases in muscle of several fish species in a mountain lake. The enhanced Hg accumulation was caused primarily by increased nutrient concentrations in the lake, which enhanced productivity and restructured the food web through increased piscivory and consumption of Mysis. This restructuring resulted in increases to the trophic positions and Hg concentrations of fishes. Forest fire also caused a large short-term release of total Hg (THg) and MeHg to streams and the lake. This release initiated a small pulse of MeHg in invertebrates that contributed to enhanced Hg accumulation by fishes. Climate change and prescribed burning to compensate for past fire suppression are predicted to increase future forest fire occurrence in North America, and increased Hg accumulation by fishes may be an unexpected consequence.productivity ͉ stable isotopes ͉ methyl mercury ͉ food chain length ͉ climate change

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Section: Resultsmentioning

confidence: 59%

mentioning

confidence: 99%

Forest fire increases mercury accumulation by fishes via food web restructuring and increased mercury inputs

Kelly

Schindler

Louis

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

133

121

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“…In many circumstances this is likely the case, particularly in areas where inorganic Hg deposition is low and bioaccumulation is driven by MeHg production and availability. Allen et al (2005) found that biomagnification was inversely correlated with chlorophyll a concentrations in a series of lakes, suggesting that biodilution regulated transfer of MeHg to higher trophic levels. Moreover, MeHg concentrations in biota were negatively correlated with pH, indicating that entry into the food web was controlled by water chemistry.…”

Section: Discussionmentioning

confidence: 96%

Mercury Trophic Transfer in a Eutrophic Lake: The Importance of Habitat‐specific Foraging

Eagles‐Smith

Suchanek

Colwell

et al. 2008

Ecological Applications

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Abstract. Mercury (Hg) trophic transfer and bioaccumulation in fish from a mineimpacted, eutrophic lake were examined in relation to foraging habitat, trophic position, and size. Diet analysis indicated that there were clear ontogenetic shifts in foraging habitats and trophic position. Pelagic diet decreased and benthic diet increased with increasing fish length in bluegill, black crappie, inland silverside, and largemouth bass, whereas there was no shift for prickly sculpin or threadfin shad. Stable carbon isotope values (d 13 C) were inversely related to the proportion of pelagic prey items in the diet, but there was no clear relationship with benthic foraging. There were distinct differences between pelagic and benthic prey basal d13 C values, with a range of approximately À28ø in pelagic zooplankton to approximately À20ø in benthic caddisflies. Profundal prey such as chironomid larvae had intermediate d13 C values of approximately À24ø, reflecting the influence of pelagic detrital subsidies and suppressing the propagation of the benthic carbon isotope signal up the food chain. Fish total mercury (TotHg) concentrations varied with habitat-specific foraging, trophic position, and size; however, the relationships differed among species and ages. When controlling for the effects of species, length, and trophic position, TotHg and d 13 C were positively correlated, indicating that Hg trophic transfer is linked to benthic foraging. When examined on a species-specific basis, TotHg was positively correlated with d 13 C only for bluegill, largemouth bass, and threadfin shad. However, diet-based multiple regression analyses suggested that TotHg also increased with benthic foraging for inland silverside and black crappie. In both species, benthic prey items were dominated by chironomid larvae, explaining the discrepancy with d 13 C. These results illustrate the importance of foraging habitat to Hg bioaccumulation and indicate that pelagic carbon can strongly subsidize the basal energy sources of benthic organisms.

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“…In lakes, burns have been shown to increase productivity due to nutrient enrichment (Garcia and Carignan 2005). Increases in productivity have led to changes in growth rates of macro-invertebrates, and in turn shifted diet preferences of fishes (Kelly et al 2006;Allen et al 2005). Dietary alterations can lead to enhanced growth of Northern Pike and other fishes, and longer food chains can occur in post-fire lakes as a result of increased productivity restructuring food webs and enhancing the trophic position of piscivores (Kelly et al 2006).…”

Section: Discussionmentioning

confidence: 99%

“…Recent literature on the effect of forest fires on lacustrine environments have focused on contaminants transfer (Allen et al 2005;Garcia and Carignan 2005;Kelly et al 2006) and fish-community interactions (St-Onge and Magnan 2000; Tonn et al 2003;. No specific information exists on the effects of forest fire on spawning and rearing Northern Pike, or their habitats in the Northwest Territories (NWT).…”

Section: Effects Of Forest Fire On Young-of-the-year Northern Pike Ementioning

confidence: 99%

Effects of Forest Fire on Young-of-the-year Northern Pike, <em>Esox lucius</em>, in the Northwest Territories

Cott

Zajdlik²,

Bourassa

et al. 2010

Can Field Nat

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In 1998, a forest fire burned 58% of the forested shoreline surrounding Tibbitt Lake, Northwest Territories, including riparian vegetation used by Northern Pike (Esox lucius) as spawning habitat. This presented an opportunity to investigate the effects that habitat disturbance from a natural forest fire had on young-of-the-year (Y-O-Y) Northern Pike. Pike fry were collected from three burned and three unburned sites around Tibbitt Lake in 1999 (the first post-fire spawning season) and again in 2001. Differences in size and relative abundance were evaluated between sites. Y-O-Y Northern Pike were significantly larger at the unburned sites (P<0.01) and the relative abundance of Y-O-Y Northern Pike increased significantly at burned sites (alpha=0.1; P<0.07) following re-vegetation two years post fire. These differences may be due to fire-induced changes in physical habitat or food availability. Forest fires decrease the density of riparian vegetation, which likely provides better spawning and rearing habitat for Northern Pike in the long-term.En 1998, un feu de forêt a brûlé 58% de la rive boisée entourant le lac Tibbitt, situé dans les Territoires du Nord-Ouest, y compris la végétation riveraine utilisé par le grand brochet (Esox lucius) comme habitat de fraie. Cet événement a présenté une occasion pour étudier les effets causés par un feu de foret sur l'habitat de jeunes de l'année du grand brochet. Les jeunes brochets ont été recueillis sur trois sites brûlées et trois sites non brûlés autour du lac Tibbitt en 1999 (la première année de fraie après le feu de forêt) et à nouveau en 2001. La différence de grandeur et l'abondance relative des poissons ont été analysés entre les différents sites. Les jeunes grands brochets aux sites non-atteints par le feu étaient considérablement plus grands (P < 0,01) que ceux aux sites brulés. Les sites brulés, subissant une rapide revégétation dans les deux années après le feu, ont augmenté en abondance relative de jeunes grands brochets (alpha = 0,1, P < 0,07). Ces différences peuvent être dues aux changements induits par le feu sur l'aspect physique de l'habitat ou sur la disponibilité de nourriture. Les incendies de forêt réduisent la densité de la végétation riveraine, qui fournit probablement de meilleure habitat de fraie et d'alevinage pour le grand brochet à long terme.

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Methyl mercury concentrations in macroinvertebrates and fish from burned and undisturbed lakes on the Boreal Plain

Cited by 40 publications

References 33 publications

Forest fire increases mercury accumulation by fishes via food web restructuring and increased mercury inputs

Forest fire increases mercury accumulation by fishes via food web restructuring and increased mercury inputs

Mercury Trophic Transfer in a Eutrophic Lake: The Importance of Habitat‐specific Foraging

Effects of Forest Fire on Young-of-the-year Northern Pike, <em>Esox lucius</em>, in the Northwest Territories

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