Understanding dietary nutrient sources is fundamental to conserving sensitive species, especially as climate change alters food web dynamics. Migratory species that depend on both marine and terrestrial habitats face unique challenges, as the locations and quality of resources in the two realms may respond quite differently to environmental changes, with potential for spatial and temporal carryover effects. For sea ducks (Mergini) that winter at sea but move inland to breed, body size may determine their capacity to store nutrient reserves for later use in alternative habitats. We assessed ultimate sources of protein for reproduction in four sea duck species in northern Alaska: smaller‐bodied Long‐tailed Ducks and Steller's Eiders (
Wetlands in Arctic tundra support abundant breeding waterbirds. Wetland types differing in area, depth, vegetation, and invertebrate biomass density may vary in importance to birds, and in vulnerability to climate change. We studied availability and use of different wetland types by prelaying females of four species of sea ducks (Mergini) breeding on the Arctic Coastal Plain of Alaska, USA: long‐tailed ducks (
- NSF-PAR ID:
- 10464243
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Ecology and Evolution
- Volume:
- 13
- Issue:
- 9
- ISSN:
- 2045-7758
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Clangula hyemalis andPolysticta stelleri ), and larger‐bodied Spectacled and King Eiders (Somateria fischeri andSomateria spectabilis ). To assess the relative use of local freshwater foods vs. marine protein for both egg production and body maintenance of incubating females, we measured stable isotopes of carbon and nitrogen in egg membranes, red blood cells, marine and freshwater invertebrates, and vegetation. For egg production, isotope mixing models indicated that proteinaceous egg membranes of all four species were derived mostly (89%–95%) from freshwater foods on the breeding grounds, with broad individual variation in specific prey types selected by the larger species. For incubation, isotopes in red blood cells indicated that body maintenance of females also relied mainly (87%–91%) on freshwater foods in Long‐tailed Ducks and Steller's Eiders. However, incubating Spectacled and King Eiders obtained only about 60% of their protein from freshwater foods and the remainder from marine‐derived body tissues. The latter strategy allows the larger‐bodied species to incubate almost continuously, whereas the smaller species must take more frequent incubation breaks and generally incur higher rates of predation on eggs. Thus, depending on body size, cross‐seasonal effects of feeding conditions in marine habitats may strongly influence population processes well after the birds move to inland nesting sites. Although conservation programs on land and sea are often researched, planned, and administered by different agencies and organizations, our results emphasize the need to coordinate marine and land‐based efforts for species that integrate conditions across both environments. -
Abstract Climate change is creating phenological mismatches between herbivores and their plant resources throughout the Arctic. While advancing growing seasons and changing arrival times of migratory herbivores can have consequences for herbivores and forage quality, developing mismatches could also influence other traits of plants, such as above‐ and below‐ground biomass and the type of reproduction, that are often not investigated.
In coastal western Alaska, we conducted a 3‐year factorial experiment that simulated scenarios of phenological mismatch by manipulating the start of the growing season (3 weeks early and ambient) and grazing times (3 weeks early, typical, 3 weeks late, or no‐grazing) of Pacific black brant (
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Synthesis . Factors affecting the timing of migration have a larger influence than earlier springs on an important forage species in the breeding and rearing habitats of Pacific black brant. The phenological mismatch prediction for this site of earlier springs and later goose arrival will likely increase above‐ and below‐ground biomass and sexual reproduction of the often‐clonally reproducingC. subspathacea . Finally, the implications of mismatch may be difficult to predict because some variables required successive years of mismatch to respond. -
Abstract High‐latitude climate change has impacted vegetation productivity, composition, and distribution across tundra ecosystems. Over the past few decades in northern Alaska, emergent macrophytes have increased in cover and density, coincident with increased air and water temperature, active layer depth, and nutrient availability. Unraveling the covarying climate and environmental controls influencing long‐term change trajectories is paramount for advancing our predictive understanding of the causes and consequences of warming in permafrost ecosystems. Within a climate‐controlled carbon flux monitoring system, we evaluate the impact of elevated nutrient availability associated with degraded permafrost (high‐treatment) and maximum field observations (low‐treatment), on aquatic macrophyte growth and methane (CH4) emissions. Nine aquatic
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Abstract Wetlands are critical components of freshwater biodiversity and provide ecosystem services, but human activities have resulted in large‐scale loss of these habitats across the globe. To offset this loss, mitigation wetlands are frequently constructed, but their ability to replicate the functions of natural wetlands remains uncertain. Further, monitoring of mitigation wetlands is limited and often focuses exclusively on vegetation and physical characteristics.
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pH ) on invertebrate richness. We also used non‐metric multidimensional scaling to visualise differences in community composition among wetland types and used indicator species analysis to determine which taxa were causing observed differences.Taxonomic richness of macroinvertebrates was lower in created wetlands than impacted or reference wetlands, whereas richness was similar in impacted and reference wetlands. Wetland age was positively correlated with taxonomic richness. The amount of aquatic vegetation in wetlands had the greatest influence on taxonomic richness, so that recently created wetlands with little vegetation had the simplest invertebrate communities. Community composition of invertebrates in created wetlands also differed from community composition in reference and impacted wetlands. Most notably, created wetlands lacked some passive dispersers that were common in other wetland types, although we found no relationship between taxonomic richness and wetland isolation.
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Daphnia abundances. However, in the late season,Daphnia appeared to be limited by photoperiod. Confirming our experimental results, our models of zooplankton biomass showed an increase of nearly 20% in warmer years. Further, these model estimates could be conservative as the consumptive demand of fishes may increase in warmer years as well.Overall, our results highlight the importance of interactive effects of temperature and seasonality. Based primarily on temperature, we can readily predict the response of fish metabolism in warmer temperatures. However, in this context, we generally require a better understanding of climate‐driven responses of important invertebrate prey resources. Our results suggest invertebrate prey biomass and availability are likely to respond positively with climate change based on temperature and seasonality, as well as proportionally to the metabolic requirements of fish predators. While further research is necessary to understand how other food‐web components will respond climate change, our findings suggest that the fish community at the top of arctic lake food webs will have adequate prey base in a warming climate.