Investigation of Heavy Metals in a Large Mortality Event in Caribou of Northern Alaska

Abstract

ABSTRACT. We measured element concentrations (As, Cd, Cu, Pb, Zn, Fe) and body condition (gross and histologic endpoints) of animals from a caribou (Rangifer tarandus) mortality event that occurred in Alaska, in the area of Point Hope and Cape Thompson (including the Chariot site), in 1995. These were compared to results from hunter-killed caribou from reference sites (Barrow and Teshekpuk Lake, Alaska) and from the area of a mine (Red Dog Mine) to determine whether heavy metals had played a role in the mortality event or whether any elements were at concentrations of concern for human consumers. Starvation and malnutrition were major factors leading to death or severe weakness, as very little or no fat (very low body condition scores) and serous atrophy of fat (observed as watery contents of the marrow cavity, with no apparent fat, and histologically) were more prevalent in caribou associated with the mortality event than in hunter-killed animals from reference sites. Accumulation of hepatic (liver) hemosiderin in Kupffer cells (macrophages) was noted as an indicator of cachexia. Concentrations of lead in feces and liver, copper in the rumen contents, and arsenic in muscle were higher in caribou harvested near Red Dog Mine, as might be expected in that mineral-rich area, but were not at levels of concern for toxicoses. Kidney concentrations of cadmium, which increased significantly with increasing age, present a potential concern for human consumers, and this is an expected finding. We concluded that caribou had starved and that heavy metals had played no role in the mortality event. Further investigation of regional mineral differences is required to understand the sources and transport mechanisms that explain these findings and to properly address mining activity. Mortality events on the north slope of Alaska are common and likely involve starvation as described here, but in most cases they are not investigated, even though recent industrial activities have heightened concern among some local residents and wildlife managers.Key words: Alaska, caribou, heavy metals, Rangifer tarandus, starvation RÉSUMÉ. On a mesuré la concentration en éléments (As, Cd, Cu, Pb, Zn, Fe) et l'état corporel (points limites bruts et histologiques) de caribous (Rangifer tarandus) prélevés lors d'un épisode de mortalité qui s'est produit en 1995 en Alaska, dans la région de Point Hope et de Cape Thompson (y compris le site Chariot). On a comparé ces résultats à ceux de caribous tués par des chasseurs à des emplacements témoins (Barrow et Teshekpuk Lake, en Alaska) et à proximité d'une mine (Red Dog Mine) pour trouver si les métaux lourds avaient joué un rôle dans l'épisode de mortalité ou si la concentration d'un ou plusieurs éléments pouvait constituer un risque pour la consommation humaine. La famine et la malnutrition étaient des facteurs majeurs ayant causé la mort ou une extrême faiblesse, vu que la présence minime ou l'absence de graisse (très basses notes d'état corporel) et une atrophie séreuse de la graisse (observée sous fo...

Essential and non-essential elements in eight tissue types from subsistencehunted bowhead whale: Nutritional and toxicological assessment

“…Compared to other species of northern Alaska, bowhead whales of this study had similar or lower tissue concentrations of the toxic metal Hg (17,18). The Cd concentrations are similar to those previously reported for bowhead whales (18,27), which accumulate Cd with age in liver, and particularly in kidney (18), similar to other arctic mammals, including both terrestrial and marine species (17,18,32,33,34,35,36,37,38,39). Other reports have addressed potential nutritional and toxic effects of such elemental concentrations in bowhead whales and domestic animals (32,18).…”

Trace Element Concentrations in Bearded Seals (Erignathus barbatus) Near Red Dog Mine Compared to Other Locations in Alaska

“…Higher concentrations of As near RDM are probably not related to mining activities. Although studies have found high levels of As in stream sediments [28] and caribou tissues [8,29], the concentration of As in ore from RDM has been shown to be no higher than that observed within local soil samples [7]. Hence, higher concentrations of As may occur naturally within the RDM region.…”

“…Dust from ore removal and transportation has been identified as a source of heavy metal contamination [2,3]. Based upon these findings, numerous assessments have quantified the risks of contamination for people using local resources for food (e.g., [4][5][6][7][8]). Although studies of marine sediments identified elevated concentrations of barium, cadmium, chromium, copper, silver, strontium, and zinc near Red Dog Mine port site, no contaminants exceeded the screening standards used to assess human health (see description of screening standards [7]).…”

The evolution of local participation and the mode of knowledge production in Arctic research

“…The number of studies with lead authors from local and territorial governments has increased over time, but these studies remain a small proportion of the papers published in Arctic, representing fewer than 7% of papers published between 2008 and 2010. Within our sample, examples include education research from the late 1990s (Stenton andRigby 1995, Norton andKassam 1997) and wildlife management studies from the last decade (O'Hara et al 2003, Person et al 2007, which actively engaged communities in every aspect of the research process. It is not surprising that papers with lead authors from local and territorial governments tend toward Mode 2 in heterogeneity, especially because they often involved authors and funding from other levels of government and/or universities.…”