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This presentation was held in January 2024 during the Danish Marine Science Meeting (22. Danske Havforskermøde). Abstract: Climate change and pollution are expected to increase in the Arctic in the future. Still, the combined impact on the marine ecosystem is not well understood. In this study, we investigated the cumulative impact of crude oil and two climate change scenarios on the feeding of the copepod species Calanus glacialis and Calanus finmarchicus. Adult females were exposed to ambient conditions and two scenarios of warming and freshening. All three conditions were tested in the absence and presence of mechanically dispersed oil (1 µL L-1). During the 6 days of exposure, incubations were renewed daily and the number of fecal pellets was counted. The fecal pellet volume was measured three times. Warming from 0 to 5°C plus freshening from 33 to 27 psu resulted in a significant increase in feeding for both species. However, when salinity dropped to 20 psu (at 5°C) feeding decreased for C. glacialis, while fluctuating for C. finmarchicus. For both species, oil had the strongest effect, leading to a 68-83% reduction in feeding, overshadowing any differences between climatic conditions. The results demonstrate the sensitivity of Arctic copepods to all three parameters, with some cumulative effects.

This presentation was held in January 2024 during the Danish Marine Science Meeting (22. Danske Havforskermøde). Abstract: Climate change and pollution are expected to increase in the Arctic in the future. Still, the combined impact on the marine ecosystem is not well understood. In this study, we investigated the cumulative impact of crude oil and two climate change scenarios on the feeding of the copepod species Calanus glacialis and Calanus finmarchicus. Adult females were exposed to ambient conditions and two scenarios of warming and freshening. All three conditions were tested in the absence and presence of mechanically dispersed oil (1 µL L-1). During the 6 days of exposure, incubations were renewed daily and the number of fecal pellets was counted. The fecal pellet volume was measured three times. Warming from 0 to 5°C plus freshening from 33 to 27 psu resulted in a significant increase in feeding for both species. However, when salinity dropped to 20 psu (at 5°C) feeding decreased for C. glacialis, while fluctuating for C. finmarchicus. For both species, oil had the strongest effect, leading to a 68-83% reduction in feeding, overshadowing any differences between climatic conditions. The results demonstrate the sensitivity of Arctic copepods to all three parameters, with some cumulative effects.

AbstractTiming of breeding, an important driver of fitness in many populations, is widely studied in the context of global change, yet despite considerable efforts to identify environmental drivers of seabird nesting phenology, for most populations we lack evidence of strong drivers. Here we adopt an alternative approach, examining the degree to which different populations positively covary in their annual phenology to infer whether phenological responses to environmental drivers are likely to be (a) shared across species at a range of spatial scales, (b) shared across populations of a species or (c) idiosyncratic to populations.We combined 51 long‐term datasets on breeding phenology spanning 50 years from nine seabird species across 29 North Atlantic sites and examined the extent to which different populations share early versus late breeding seasons depending on a hierarchy of spatial scales comprising breeding site, small‐scale region, large‐scale region and the whole North Atlantic.In about a third of cases, we found laying dates of populations of different species sharing the same breeding site or small‐scale breeding region were positively correlated, which is consistent with the hypothesis that they share phenological responses to the same environmental conditions. In comparison, we found no evidence for positive phenological covariation among populations across species aggregated at larger spatial scales.In general, we found little evidence for positive phenological covariation between populations of a single species, and in many instances the inter‐year variation specific to a population was substantial, consistent with each population responding idiosyncratically to local environmental conditions. Black‐legged kittiwakeRissa tridactylawas the exception, with populations exhibiting positive covariation in laying dates that decayed with the distance between breeding sites, suggesting that populations may be responding to a similar driver.Our approach sheds light on the potential factors that may drive phenology in our study species, thus furthering our understanding of the scales at which different seabirds interact with interannual variation in their environment. We also identify additional systems and phenological questions to which our inferential approach could be applied.

AbstractTiming of breeding, an important driver of fitness in many populations, is widely studied in the context of global change, yet despite considerable efforts to identify environmental drivers of seabird nesting phenology, for most populations we lack evidence of strong drivers. Here we adopt an alternative approach, examining the degree to which different populations positively covary in their annual phenology to infer whether phenological responses to environmental drivers are likely to be (a) shared across species at a range of spatial scales, (b) shared across populations of a species or (c) idiosyncratic to populations.We combined 51 long‐term datasets on breeding phenology spanning 50 years from nine seabird species across 29 North Atlantic sites and examined the extent to which different populations share early versus late breeding seasons depending on a hierarchy of spatial scales comprising breeding site, small‐scale region, large‐scale region and the whole North Atlantic.In about a third of cases, we found laying dates of populations of different species sharing the same breeding site or small‐scale breeding region were positively correlated, which is consistent with the hypothesis that they share phenological responses to the same environmental conditions. In comparison, we found no evidence for positive phenological covariation among populations across species aggregated at larger spatial scales.In general, we found little evidence for positive phenological covariation between populations of a single species, and in many instances the inter‐year variation specific to a population was substantial, consistent with each population responding idiosyncratically to local environmental conditions. Black‐legged kittiwakeRissa tridactylawas the exception, with populations exhibiting positive covariation in laying dates that decayed with the distance between breeding sites, suggesting that populations may be responding to a similar driver.Our approach sheds light on the potential factors that may drive phenology in our study species, thus furthering our understanding of the scales at which different seabirds interact with interannual variation in their environment. We also identify additional systems and phenological questions to which our inferential approach could be applied.

Climate warming has caused the seasonal timing of many components of ecological food chains to advance. In the context of trophic interactions, the match-mismatch hypothesis postulates that differential shifts can lead to phenological asynchrony with negative impacts for consumers. However, at present there has been no consistent analysis of the links between temperature change, phenological asynchrony and individual-to-population-level impacts across taxa, trophic levels and biomes at a global scale. Here, we propose five criteria that all need to be met to demonstrate that temperature-mediated trophic asynchrony poses a growing risk to consumers. We conduct a literature review of 109 papers studying 129 taxa, and find that all five criteria are assessed for only two taxa, with the majority of taxa only having one or two criteria assessed. Crucially, nearly every study was conducted in Europe or North America, and most studies were on terrestrial secondary consumers. We thus lack a robust evidence base from which to draw general conclusions about the risk that climate-mediated trophic asynchrony may pose to populations worldwide.

Climate warming has caused the seasonal timing of many components of ecological food chains to advance. In the context of trophic interactions, the match-mismatch hypothesis postulates that differential shifts can lead to phenological asynchrony with negative impacts for consumers. However, at present there has been no consistent analysis of the links between temperature change, phenological asynchrony and individual-to-population-level impacts across taxa, trophic levels and biomes at a global scale. Here, we propose five criteria that all need to be met to demonstrate that temperature-mediated trophic asynchrony poses a growing risk to consumers. We conduct a literature review of 109 papers studying 129 taxa, and find that all five criteria are assessed for only two taxa, with the majority of taxa only having one or two criteria assessed. Crucially, nearly every study was conducted in Europe or North America, and most studies were on terrestrial secondary consumers. We thus lack a robust evidence base from which to draw general conclusions about the risk that climate-mediated trophic asynchrony may pose to populations worldwide.