BIOMAGNIFICACIÓN DE MERCURIO EN TRAMAS TRÓFICAS ACUATICAS COSTERAS DE AMBIENTES AISLADOS DEL PACIFICO SUR, PATAGONIA Y ANTÁRTICA.

CHIANG, G.; KIDD, K.; O`DRISCOLL; DÍAZ JARAMILLO, M.; JARA CARRASCO, S.; MUNKITTRICK, K.R.

Concepción

Congreso; XXXVI Congreso de Ciencias del Mar 2016; 2016

Universidad de Concepción

Mercury (Hg) occurs naturally in the environment, but anthropogenic activities have increased Hg emissions through fossil fuel combustion and mining. Mercury (Hg) is a global pollutant due to its long distance transport and potential for methylation into the toxic and bioaccumulative form, methylmercury (MeHg). Many studies have examined MeHg and its trophic transfer in Northern aquatic ecosystems however, much less information is available for systems in the southern hemisphere. Recent studies have shown that Hg concentrations in shallow waters has triplicated and Hg biomagnification rates are higher in food webs from colder and less productive aquatic ecosystems. Chilean Patagonia and the coast of Antarctic Peninsula are a hotspot of biodiversity with little industrial activity and unique geological (e.g. volcanos) and physical (e.g. high orographic precipitation rate) characteristics, making it an optimal place to study atmospherically-sourced Hg in the Southern Hemisphere. Melimoyu Bay (Patagonia), Livingstone Island (Southern Shetlands) and Paradise bay (Antarctic Peninsula) were selected to assess food web structure and mercury concentrations in biota. We assessed food web structure using stable isotope analysis (δ13C & δ15N) and fish stomach content. The samples were also analyzed for total (THg) and methylmercury (MeHg). Preliminary data shows that marine mammals (seals, sea lions and whales), marine birds (skuas and penguins) and benthic predatory fish have higher THg (0.033-3.124 μg/g d.w.) concentrations and forage in a very similar habitat (overlapping δ13C values). Benthic invertebrates (seastars, seasnails, amphipods, krill) have low MeHg (0.003-0.1285 μg/g d.w.) with seastars showing the highest concentrations of any invertebrate. Regression models for the whole food web (logMeHg and logTHg vs δ15N) show a higher positive slope for logMeHg. Higher biomagnification slopes were observed at the river discharge in (0.243), meanwhile further offshore in Patagonia it was lower (0.199) than the slope observed in Paradise bay (0.217). This data shows that freshwater output plays a major role on mercury biomagnification on coastal waters, and that there is a latitudinal difference on this process too, showing that biomagnification process is similar in Patagonian-Antarctic marine food webs to those found in polar zones in the northern hemisphere.