Periodic Reporting for period 1 - DeToxSea (Demographical effects of toxic contamination on Arctic seabirds)
Berichtszeitraum: 2021-05-01 bis 2023-04-30
Mercury (Hg) concentrations in the oceans have tripled in the last centuries, even in remote areas such as the Arctic. Hg is bioaccumulated in food webs and can produce toxic effects affecting breeding and survival probabilities in wildlife. Selenium (Se) has been proven to have a protective effect against Hg toxicity, but no long-term studies have been carried out to evaluate reproductive output and population dynamics in relation to Se or the interaction Se-Hg. Using as a population model the most abundant breeding bird in the Arctic, the little auk (Alle alle), we aim to 1) evaluate the temporal trends of Se/Hg and on which environmental/individual factors they depend; 2) investigate if Se/Hg concentrations affect the reproductive output of little auks; and 3) evaluate the effects of Se/Hg at the population level in the context of climate change (i.e. considering environmental conditions). To do so, we will 15 years of data of little auks from west Greenland (Kape Høegh). I will analyse pollutants on blood samples at the host laboratory, and I will perform different statistical approaches to investigate our objectives. In particular, we will look for functional relationships to evaluate pollutant temporal/environmental trends and their toxic effects on the reproductive output of little auks; and demographic models (multistate mark-recapture models) to evaluate the projected population growth rate and its sensitivity to Hg/Se and environmental conditions. This research program will gather knowledge from a large interdisciplinary team, with expertise in ecotoxicology and demography. We anticipate major public interest in the results of DeToxSea: the unique long-term study about demographic effects of Se/Hg toxic contamination in arctic wildlife, that will give light on one of the Challenges of Horizon 2020 about Climate Action, Environment, Resource Efficiency and Raw Materials.
In the first contribution of the DeToxSea project, the large-scale spatial distribution of mercury (Hg) and selenium (Se) throughout the Arctic has been evaluated for the first time in the Arctic, in two seabird species in the Arctic and subarctic regions, the Brünnich's guillemot and the black-legged kittiwake. Differences in Hg and Se spatial distribution highlight the need of evaluating Hg and Se concentrations together when assessing the toxic risk related to Hg. This is especially important for international monitoring programs focusing on the risks of Hg toxicity in marine predators and possible mitigation measures. Moreover, the absence of a consistent pattern between Hg and Se with nitrogen and carbon isotopes (δ15N and δ13C, respectively) suggests high variability in the foraging strategy of both species as well as high variability in isotopes baselines over the large scale of the study. The results of this study have been presented to the French and Spanish research communities at the National Committee for Antarctic and Arctic Research (CNFRA) 18th Scientific Conference and to the 25th Conference of the SEO/BirdLife, respectively; and to the general public in La Radio del Somormujo (November 2022).
In a second contribution, the effects of multiple environmental stressors (Se, Hg, and environmental conditions) have been evaluated on a keystone Arctic seabird demography, the little auk from East Greenland. Hg and Se concentrations have no significant effect on little auk survival. However, we found that environmental conditions had a major influence on survival. The anomaly in sea surface temperature during the breeding season is the variable with the greatest influence on the survival of little auks: an increase in SSTA during the breeding at Year t-3 will produce a reduction of the survival at Year t+1, most likely due to a cascade effect through the food chain. However, we found a positive effect on survival at Year t+1 when the SSTA of the moulting area at Year t increases, most likely due to a benefit in the short term, since little auks would need to travel less to feed, as sea ice covering would be reduced due to the increase in temperature, increasing the availability of prey close to the colony. This study will be among the first initiatives to thoroughly address the effect of different pollutants on the survival of wild animal populations in a multi-stress context.
Finally, in the last contribution, we aimed at evaluating the temporal trends of different trace element concentrations in little auks from East Greenland, as well as how they depended on the trophic ecology of the individuals or the environmental conditions. The concentrations of trace elements in the blood of little auks differed significantly among years, and some metals followed similar annual variation patterns. For example, cadmium (Cd) or lead (Pb) showed higher concentrations in 2011, 2012, and 2013; while in 2014 arsenic (As), copper (Cu), or manganese (Mn) showed higher concentrations but the lowest for iron (Fe) or zinc (Zn). We found also lower values from 2015 to 2021 for Cu and Pb than in the previous years. Preliminary models showed that As concentrations varied positively with the δ15N and negatively with δ13C. Cd concentrations varied positively with δ13C and with the Atlantic Oscillation (AO) during spring. Fe concentrations varied negatively with δ13C and positively with AO during spring. Hg concentrations varied positively with δ15N and with AO. Zn concentrations varied negatively with δ13C and with annual AO. The concentrations of the other trace elements (Cu, Mn, Pb, and Se) were not explained by the trophic ecology or the environmental conditions. To our knowledge, this study constitutes the first evaluation of blood concentrations of trace elements in little auks except for Hg. In general, we did not find obvious differences with the concentrations found for other Arctic species. However, we evidenced the influence of the trophic ecology and the environmental conditions on the concentration of different trace elements. New, more precise models will be developed using the environmental variables mentioned in the previous contribution to explain variations in trace elements in the little auks.
The specific results of these two last contributions have not been disseminated yet. However, the framework and aims of DeToxSea have been disseminated in a film at the XVI “Not Too Scientific Film” Festival organized by the University of La Rochelle, which was awarded the Audience and Best Dissemination Film prizes; and through a website and a blog created for the project: https://martacruzflores.wixsite.com/detoxseaproject(öffnet in neuem Fenster).
In a second contribution, the effects of multiple environmental stressors (Se, Hg, and environmental conditions) have been evaluated on a keystone Arctic seabird demography, the little auk from East Greenland. Hg and Se concentrations have no significant effect on little auk survival. However, we found that environmental conditions had a major influence on survival. The anomaly in sea surface temperature during the breeding season is the variable with the greatest influence on the survival of little auks: an increase in SSTA during the breeding at Year t-3 will produce a reduction of the survival at Year t+1, most likely due to a cascade effect through the food chain. However, we found a positive effect on survival at Year t+1 when the SSTA of the moulting area at Year t increases, most likely due to a benefit in the short term, since little auks would need to travel less to feed, as sea ice covering would be reduced due to the increase in temperature, increasing the availability of prey close to the colony. This study will be among the first initiatives to thoroughly address the effect of different pollutants on the survival of wild animal populations in a multi-stress context.
Finally, in the last contribution, we aimed at evaluating the temporal trends of different trace element concentrations in little auks from East Greenland, as well as how they depended on the trophic ecology of the individuals or the environmental conditions. The concentrations of trace elements in the blood of little auks differed significantly among years, and some metals followed similar annual variation patterns. For example, cadmium (Cd) or lead (Pb) showed higher concentrations in 2011, 2012, and 2013; while in 2014 arsenic (As), copper (Cu), or manganese (Mn) showed higher concentrations but the lowest for iron (Fe) or zinc (Zn). We found also lower values from 2015 to 2021 for Cu and Pb than in the previous years. Preliminary models showed that As concentrations varied positively with the δ15N and negatively with δ13C. Cd concentrations varied positively with δ13C and with the Atlantic Oscillation (AO) during spring. Fe concentrations varied negatively with δ13C and positively with AO during spring. Hg concentrations varied positively with δ15N and with AO. Zn concentrations varied negatively with δ13C and with annual AO. The concentrations of the other trace elements (Cu, Mn, Pb, and Se) were not explained by the trophic ecology or the environmental conditions. To our knowledge, this study constitutes the first evaluation of blood concentrations of trace elements in little auks except for Hg. In general, we did not find obvious differences with the concentrations found for other Arctic species. However, we evidenced the influence of the trophic ecology and the environmental conditions on the concentration of different trace elements. New, more precise models will be developed using the environmental variables mentioned in the previous contribution to explain variations in trace elements in the little auks.
The specific results of these two last contributions have not been disseminated yet. However, the framework and aims of DeToxSea have been disseminated in a film at the XVI “Not Too Scientific Film” Festival organized by the University of La Rochelle, which was awarded the Audience and Best Dissemination Film prizes; and through a website and a blog created for the project: https://martacruzflores.wixsite.com/detoxseaproject(öffnet in neuem Fenster).
The research carried out has given light on one of the seven major Societal Challenges that Europe has to face, entitled “Climate action, environment, resource efficiency and raw materials”, and globally into “Life below water” UN Sustainable Development Goals. The results of the DeToxSea project have been already presented to the Hg Expert Group of the Arctic Monitoring and Assessment Programme of the Arctic Council, and will be transferred to Arctic policy-makers, and it has provided insights to evaluate and further understand the spatial distribution of Hg and Se in Arctic marine predators, as well as the influence of environmental conditions their concentrations, what is important for international monitoring programs focusing on toxicity risk in marine predators and possible mitigation measures.