[1] Coastal ecosystems respond to sea level and sediment supply change according to complex, three-way interactions between vegetation, hydrology, and sediment transport. While biogeomorphic feedbacks preserve the morphology of intertidal surfaces covered by marshland, we demonstrate with numerical model and field experimentation that temporary disturbance to vegetation facilitates rapid and widespread degradation. Vertical accretion slows in disturbed areas, allowing localized submergence of the marsh platform, tidal prism enlargement, and permanent channel network expansion. Vegetated portions of an episodically disturbed platform accrete more rapidly than rates of relative sea level rise, giving submerging marshland the appearance of maintaining elevation. This feedback between vegetation disturbance and channel erosion, and its effect on platform accretion, may explain peculiar patterns of wetland loss in Europe and North America.
The Arctic is entering a new ecological state, with alarming consequences for humanity. Animal-borne sensors offer a window into these changes. Although substantial animal tracking data from the Arctic and subarctic exist, most are difficult to discover and access. Here, we present the new Arctic Animal Movement Archive (AAMA), a growing collection of more than 200 standardized terrestrial and marine animal tracking studies from 1991 to the present. The AAMA supports public data discovery, preserves fundamental baseline data for the future, and facilitates efficient, collaborative data analysis. With AAMA-based case studies, we document climatic influences on the migration phenology of eagles, geographic differences in the adaptive response of caribou reproductive phenology to climate change, and species-specific changes in terrestrial mammal movement rates in response to increasing temperature.
We compared density and morphology of wild mussels Mytilus trossulus growing naturally on shellfish farming structures to that of mussels from nearby intertidal areas, and considered the relevance to molluscivorous sea ducks. Mussel density on aquaculture structures greatly exceeded that of intertidal areas and farm mussels were larger, had lower shell mass, and had weaker byssal attachments. Differences in environmental conditions and predation regimes throughout the summer growing season were likely responsible for these differences. These morphological and density differences, in turn, have important implications for their primary winter predators, sea ducks, including surf scoters Melanitta perspicillata and Barrow's goldeneyes Bucephala islandica. Higher levels of mussel depletion in farm habitats and strong associations of ducks with shellfish farms indicate that sea ducks responded to this novel, profitable prey resource. Our results support recent research that indicates that artificial structures introduced into coastal areas create novel marine habitats that can support unique communities of epibiota. That sea ducks appear to profit from the introduction of aquaculture structures is evidence of a positive effect of anthropogenic modifications in a coastal environment.
Since the mid 1990s, the number of black brant (Branta bernicla nigricans; brant) nests on the Yukon-Kuskokwim Delta (YKD), Alaska, USA, the historically predominant breeding area of brant, has declined steadily. This has caused researchers and managers to question if arctic breeding populations can compensate for the reduction in brant nests on the YKD. An important component of the assessment of brant population dynamics is having current estimates of first-year and adult survival. We banded brant at 4 locations in Arctic Alaska and western Canada, and at 1 location in the subarctic, the Tutakoke River (TR) colony on the YKD, 1990-2015. We used joint live and dead mark-recapture models to estimate first-year and adult (!1 yr old) survival of brant. We also used band recovery rates from a Brownie model to assess temporal trends in band recovery rates of adult brant. First-year survival of brant hatched at TR declined from approximately 0.60 to <0.20 and, although first-year survival generally was higher for goslings marked in the Arctic, their survival declined from approximately 0.70 in the early 1990s to 0.45 in the 2010s. Annual survival of adult females decreased from an average of 0.881 (95% CI ¼ 0.877-0.885) to 0.822 (95% CI ¼ 0.815-0.829) at TR and from 0.851 (95% CI ¼ 0.843-0.860) to 0.821 (95% CI ¼ 0.805-0.836) in the Arctic, from 1990 to 2014. Band recovery rates of adults generally were <1.25% until the last several years of study, when they reached 3.5%. Although the current harvest rates may be partially additive to natural mortality, we do not believe that harvest is the main influence on the declines in survival. The general decline in survival rates of brant breeding across a large geographic area may be influenced by a reduction in the quality of migration and wintering ground habitats. We suggest an analysis of seasonal survival of brant to test the hypothesis that declining habitat quality on wintering or spring migration areas is reducing survival. Our results suggest that the number of breeding pairs at TR will continue to decline and also brings into question the ability of arctic breeding populations to grow at a rate necessary to offset the declines on the YKD. Researchers should continue to closely monitor survival and harvest rates of brant, and assess methods currently used to monitor their abundance. Ó 2017 The Wildlife Society.KEY WORDS band recovery rates, Branta bernicla nigricans, Brownie models, joint live and dead mark-recapture, population dynamics, Seber reporting rate.
Demographic parameter estimates are essential for understanding population ecology and developing management plans for species of concern. We inferred measures of breeding success using radiotelemetry in the marbled murrelet (Brachyramphus marmoratus), a secretive, forest‐nesting seabird, from 1998 to 2001 in Desolation Sound, British Columbia, Canada. Our estimates of mean annual nesting success and fecundity (0.19–0.23 female offspring/adult female/yr) are among the highest reported for the species. We suspect that our estimates are high compared to previous estimates in our study area (Manley 1999), primarily because of our higher success in areas inaccessible to ground‐based human observers. We detail how behavior‐based inferences of activity at different reproductive stages did not differ between confirmed nest sites and suspected nest sites that were physically inaccessible to us. We were able to accurately predict initiations of breeding and incubation success from the duration of adults' repeated daily shifts from the ocean to their inland nest sites. Chick‐rearing success was accurately predicted by visitation rates of adults during provisioning. We discuss the assumptions and potential biases of our methods and their effects on our results. Our method may overestimate early breeding failure, but it likely provided unbiased fecundity estimates for our population. Accurately inferring breeding success through radiotelemetry is costly and labor intensive. However, radiotelemetry could provide crucial demographic information once thought impossible to obtain for secretive breeding species.
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