Search

Fish mercury (Hg) concentrations have been measured over the last 30-40 years in all regions of Canada as part of various monitoring and research programs. Despite this large amount of data, only regional assessments of fish Hg trends and patterns have previously been attempted. The objective of this study was to assemble available freshwater fish Hg concentration data from all provinces and territories and identify national patterns. The Canadian Fish Mercury Database includes over 330 000 records representing 104 species of freshwater fish collected from over 5000 locations across Canada between 1967 and 2010. Analysis of the 28 most frequently occurring species (>1000 records) showed that the majority of variation in Hg concentrations (when normalized to a standard size) was accounted for by geographic location. Median Hg concentrations increased with trophic level (r = 0.40, p < 0.05), with the highest Hg concentrations found in piscivorous species such as walleye (Sander vitreus), northern pike (Esox lucius), and lake trout (Salvelinus namaycush). The Canadian Fish Mercury Database provides the most comprehensive summary of fish Hg measurements in Canada, and the results indicate that several regionally observed trends in fish Hg concentrations (e.g., Hgbiomagnification and geographic variation) are observed at a national scale. Implications for the effective assessment of changes in fish Hg concentrations in relation to changes in Hg emission regulations are discussed. Les concentrations de mercure (Hg) dans le poisson sont mesurees depuis 30 ou 40 ans dans toutes les regions du Canada, dans le cadre de divers programmes de surveillance et de recherche. Malgre cette vaste quantite de donnees, seules des evaluations regionales des tendances et distributions du Hg dans le poisson ont ete effectuees par le passe. L'objectif de l'etude consistait a regrouper les donnees disponibles sur les concentrations de Hg dans les poissons dulcicoles pour toutes les provinces et tous les territoires et a cerner les motifs de distribution a l'echelle nationale. La base de donnees canadienne sur le mercure dans le poisson (' Canadian Fish Mercury Database ') comprend plus de 330 000 entrees representant 104 especes de poisons dulcicoles echantillonnes dans plus de 5000 localites a la grandeur du pays, de 1967 a 2010. L'analyse des 28 especes les plus frequentes (>1000 entrees) a demontre que la situation geographique expliquait la majeure partie de la variabilite des concentrations de Hg (normalisees en fonction d'une taille standard). Les concentrations medianes de Hg augmentaient parallelement au niveau trophique (r = 0,40, p < 0,05), les poissons piscivores comme le dore (Sander vitreus), le grand brochet (Esox lucius)etle touladi (Salvelinus namaycush) presentant les plus fortes concentrations. La base de donnees canadienne sur le mercure dans le poisson constitue la synthese la plus exhaustive des mesures de Hg dans le poisson au Canada, et les resultats indiquent que plusieurs tendances observees a l'echelle regionale des concentrations de Hg dans le poisson (p. ex. bioamplification et variations geographiques du Hg) sont egalement observees a l'echelle nationale. Les consequences de ces resultats en ce qui concerne l'evaluation efficace de l'evolution des concentrations de Hg dans le poisson par rapport aux modifications de la reglementation en matiere d'emissions de Hg sont abordees. [Traduit par la Redaction], Introduction Anthropogenic activities have contributed to the increase in the global atmospheric mercury (Hg) pool during the 20th century (Pacyna et al. 2010). In Canada, with the exception of known [...]

Mercury (Hg) concentrations in fish from acidic lakes (pH < 6.0) are typically elevated above those from nearneutral systems. It is unknown whether high biomagnification rates through the supporting food web can explain elevated Hg concentrations in top predators from low pH lakes. To investigate this, we collected yellow perch (Perca flavescens), brown bullhead (Ameiurus nebulosus), banded killifish (Fundulus diaphanous), golden shiner (Notemigonus crysoleucas), and littoral and pelagic invertebrates from four acidic lakes in Kejimkujik National Park and Historic Site (KNPNHS), Nova Scotia, Canada, and analyzed them for total Hg and methyl Hg (MeHg), and [[delta].sup.13]C and [[delta].sup.15]N to determine sources of energy and trophic position, respectively. Mercury biomagnification rates (slopes of log Hg versus [[delta].sup.15]N) varied significantly among the four lakes but did not explain the among-lake differences in perch Hg; these slopes were also within the range published for near-neutral systems. Rather, Hg concentrations in yellow perch (i.e., predatory fish) in KNPNHS were higher in lakes with higher MeHg in lower-trophic-level organisms and suggest that processes influencing Hg uptake at the base of the food web are more important than rates of food web biomagnification for understanding the variation in concentrations of this contaminant among top predators. Les concentrations de mercure (Hg) dans les poissons des lacs acides (pH < 6,0) sont typiquement plus elevees que celles des poissons de systemes pres de la neutralite. On ne sait pas si ce sont des taux eleves de bioamplification a travers le reseau alimentaire de support qui peuvent expliquer les concentrations elevees de Hg dans les predateurs superieurs des lacs a pH bas. Pour etudier la question, nous avons preleve des perchaudes (Perca flavescens), des barbottes brunes (Ameiurus nebulosus), des fondules barres (Fundulus diaphanus), des chattes de l'est (Notemigonus crysoleucas), ainsi que des invertebres littoraux et pelagiques dans quatre lacs acides du parc national et lieu historique national de Kejimkujik (KNPNHS), Nouvelle-E cosse, Canada, et nous avons dose le Hg total et le methylmercure (MeHg) et calcule les valeurs de [[delta].sup.13]C et de [[delta].sup.15]N afin de determiner respectivement les sources d'energie et la position trophique. Les taux de bioamplification du mercure (pentes de log Hg sur [[delta].sup.15]N) varient significativement entre les quatre lacs, mais n'expliquent pas les differences de Hg chez les perchaudes dans ces differents lacs; ces pentes se retrouvent aussi dans la gamme des pentes publiees pour les lacs pres de la neutralite. Au contraire, les concentrations de Hg chez les perchaudes (des poisons predateurs) dans le KNPNHS sont plus fortes dans les lacs qui ont plus de MeHg dans les organismes de niveau trophique inferieur; cela laisse croire que les processus qui influencent l'incorporation de Hg a la base du reseau alimentaire sont plus importants que les taux de bioamplification dans le reseau alimentaire pour expliquer la variation des concentrations de ce contaminant chez les predateurs de niveau superieur. [Traduit par la Redaction], Introduction Mercury (Hg) contamination of freshwater ecosystems became a widespread issue decades ago, yet the variation in Hg concentrations among top predators from different lakes still has not been completely [...]

Although the presence and distribution of polychlorinated biphenyls (PCBs) in Arctic marine environments has been well documented, the implications for the health of biota are poorly understood. In the present study, multiple lines of evidence, including site-specific effects data, were used to assess PCB-related risks to marine biota at a contaminated military site in Saglek Bay, Labrador, Canada, from 1997 to 1999. Risks were evaluated for three components of the ecosystem: benthic invertebrates, a bottom-feeding fish (shorthorn sculpin, Myoxocephalus scorpius), and a diving seabird (black guillemot, Cepphus grylle). Average sediment PCB concentrations exceeded the Canadian interim sediment quality guideline level by 41-fold. However, sediment toxicity testing and a benthic community survey showed no evidence of adverse effects. In contrast, shorthorn sculpin and black guillemot PCB exposures (measured as sum of 55 congeners) were elevated enough to pose risks to survival or reproduction. Based on the collective evidence, the authors estimated that risks were posed by sediment PCB concentrations greater than 77 ng/g dry weight for black guillemots and 750 ng/g dry weight for shorthorn sculpins. The present study, along with two parallel studies, provided information to support the management decisions concerning potential remedial action on the contaminated sediments. This ecological risk assessment describes the steps and rationale taken to evaluate the risk posed by an area of PCB-contaminated marine sediments in an otherwise relatively pristine northern coastal environment. Environ. Toxicol. Chem. 2013;32:453-467. © 2012 SETAC [ABSTRACT FROM AUTHOR]