Some of the longest and most comprehensive marine ecosystem monitoring programs were established in the Gulf of Alaska following the environmental disaster of the Exxon Valdez oil spill over 30 years ago. These monitoring programs have been successful in assessing recovery from oil spill impacts, and their continuation decades later has now provided an unparalleled assessment of ecosystem responses to another newly emerging global threat, marine heatwaves. The 2014–2016 northeast Pacific marine heatwave (PMH) in the Gulf of Alaska was the longest lasting heatwave globally over the past decade, with some cooling, but also continued warm conditions through 2019. Our analysis of 187 time series from primary production to commercial fisheries and nearshore intertidal to offshore oceanic domains demonstrate abrupt changes across trophic levels, with many responses persisting up to at least 5 years after the onset of the heatwave. Furthermore, our suite of metrics showed novel community-level groupings relative to at least a decade prior to the heatwave. Given anticipated increases in marine heatwaves under current climate projections, it remains uncertain when or if the Gulf of Alaska ecosystem will return to a pre-PMH state.

Long‐term studies of predator food habits (i.e., ‘predator‐based sampling’) are useful for identifying patterns of spatial and temporal variability of forage nekton in marine ecosystems. We investigated temporal changes in forage fish availability and relationships to ocean climate by analyzing diet composition of three puffin species (horned puffin Fratercula corniculata, tufted puffin Fratercula cirrhata, and rhinoceros auklet Cerorhinca monocerata) from five sites in the North Pacific from 1978–2012. Dominant forage species included squids and hexagrammids in the western Aleutians, gadids and Pacific sand lance (Ammodytes personatus) in the eastern Aleutians and western Gulf of Alaska (GoA), and sand lance and capelin (Mallotus villosus) in the northern and eastern GoA. Interannual fluctuations in forage availability dominated variability in the western Aleutians, whereas lower‐frequency shifts in forage fish availability dominated elsewhere. We produced regional multivariate indicators of sand lance, capelin, and age‐0 gadid availability by combining data across species and sites using Principal Component Analysis, and related these indices to environmental factors including sea level pressure (SPL), winds, and sea surface temperature (SST). There was coherence in the availability of sand lance and capelin across the study area. Sand lance availability increased linearly with environmental conditions leading to warmer ocean temperatures, whereas capelin availability increased in a non‐linear manner when environmental changes led to lower ocean temperatures. Long‐term studies of puffin diet composition appear to be a promising tool for understanding the availability of these difficult‐to‐survey forage nekton in remote regions of the North Pacific.

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Resumen. examinamos la ecología de nidificación de Euphagus carolinus a través del monitoreo de 162 nidos para obtener datos de supervivencia de nidos en alaska y de 252 registros adicionales de alaska y canadá para identificar habitats importantes para la nidificación y evaluar si las bajas tasas de éxito de nidos contribuyeron a las disminuciones poblacionales en alaska. en la costa de alaska y a lo largo de canadá, los nidos se encontraron principalmente en coníferas (85% de 212 nidos). todos los nidos en coníferas de alaska y el 80% de los de canadá estuvieron ubicados en ejemplares de Picea spp., principalmente P. mariana. en alaska se identificó un uso selectivo de ejemplares pequeños de Picea (<8 cm dap), resultando en un alto éxito reproductivo-la supervivencia de los nidos incrementó con la densidad de P. mariana, y el éxito de nidos en ejemplares de Picea (79%) fue mayor que el de los nidos ubicados en vegetación decidua (52%). la supervivencia de nidos en ejemplares más altos de Picea disminuyó, posiblemente debido a la depredación por parte de Tamiasciurus hudsonicus. los individuos de E. carolinus nidificaron cerca del agua en el interior (x _ = 8 m) y en el sur centro de alaska (x _ = 30 m), y los ejemplares pequeños de Picea parecieron ser importantes dentro de la mayor parte del área de distribución de la especie. Sin embargo, en el interior de alaska, la mayoría de los nidos se ubicaron en ejemplares de Salix (78%), los que dominaban la vegetación cercana al agua. el éxito de nidos en alaska promedió el 56%, similar a las tasas del mismo periodo en nueva inglaterra pero mayor que las de otras especies de Euphagus de américa del norte. Son necesarios estudios para verificar si la supervivencia de nidos es alta también en canadá y para investigar dónde y cómo el déficit en la supervivencia de adultos o juveniles puede estar limitando el crecimiento poblacional.neSting ecology of the RuSty BlackBiRd in alaSka and canada ecología de nidificación de Euphagus carolinus en alaska y canadá Abstract. we examined the nesting ecology of the Rusty Blackbird (Euphagus carolinus) from 162 nests monitored for nest survival in alaska and 252 incidental records from alaska and canada to identify important habitats for nesting and to test whether low rates of nest success are contributing to populations declines in alaska. in coastal alaska and throughout canada, nests were primarily in conifers (85% of 212 nests). all conifer nests in alaska and 80% of those in canada were placed in spruce (Picea spp.), primarily black spruce (P. mariana). in alaska use of small spruces (<8 cm dbh) was selective and resulted in high reproductive success-nest survival increased with black spruce density, and success of nests in spruce (79%) was higher than that of nests in deciduous vegetation (52%). Survival of nests in taller spruce declined, possibly from predation by red squirrels (Tamiasciurus hudsonicus). Rusty Blackbirds nested near water in interior (x _ = 8 m) and south-central alaska (x _ = 30 m), and small spruces near ...

Mercury (Hg) is a natural trace element found in high concentrations in top predators, including Arctic seabirds. Most current knowledge about Hg concentrations in Arctic seabirds relates to exposure during the summer breeding period when researchers can easily access seabirds at colonies. However, the few studies focused on winter have shown higher Hg concentrations during the non-breeding period than breeding period in several tissues. Hence, improving knowledge about Hg exposure during the non-breeding period is crucial to understanding the threats and risks encountered by these species year-round. We used feathers of nine migratory alcid species occurring at high latitudes to study bird Hg exposure during both the breeding and non-breeding periods. Overall, Hg concentrations during the nonbreeding period were ~3 times higher than during the breeding period. In addition, spatial differences were apparent within and between the Atlantic and Pacific regions. While Hg concentrations during the non-breeding period were ~9 times and ~3 times higher than during the breeding period for the West and East Atlantic respectively, Hg concentrations in the Pacific during the non-breeding period were only ~1.7 times higher than during the breeding period. In addition, individual Hg concentrations during the non-breeding period for most of the seabird colonies were above 5.00 µg g-1 dry weight (dw), which is considered to be the threshold at which deleterious effects are observed, suggesting that some breeding populations might be vulnerable to non-breeding Hg exposure. Since wintering area locations, and migration routes may influence seasonal Hg concentrations, it is crucial to improve our knowledge about spatial ecotoxicology to fully understand the risks associated with Hg contamination in Arctic seabirds.