Human alteration of land cover (e.g., urban and agricultural land use) and shoreline hardening (e.g., bulkheading and rip rap revetment) are intensifying due to increasing human populations and sea level rise. Fishes and crustaceans that are ecologically and economically valuable to coastal systems may be affected by these changes, but direct links between these stressors and faunal populations have been elusive at large spatial scales. We examined nearshore abundance patterns of 15 common taxa across gradients of urban and agricultural land cover as well as wetland and hardened shoreline in tributary subestuaries of the Chesapeake Bay and Delaware Coastal Bays. We used a comprehensive landscape-scale study design that included 587 sites in 39 subestuaries. Our analyses indicate shoreline hardening has predominantly negative effects on estuarine fauna in water directly adjacent to the hardened shoreline and at the larger system-scale as cumulative hardened shoreline increased in the subestuary. In contrast, abundances of 12 of 15 species increased with the proportion of shoreline comprised of wetlands. Abundances of several species were also significantly related to watershed cropland cover, submerged aquatic vegetation, and total nitrogen, suggesting land-use-mediated effects on prey and refuge habitat. Specifically, abundances of four bottom-oriented species were negatively related to cropland cover, which is correlated with elevated nitrogen and reduced submerged and wetland vegetation in the receiving subestuary. These empirical relationships raise important considerations for conservation and management strategies in coastal environments.

Wetland managers have historically considered riprap‐sill structures (a type of “living shoreline” consisting of a rock sill that is placed low in the intertidal zone, with native vegetation planted between the sill and the shore) to be more ecologically sound than the riprap that is traditionally applied for shoreline stabilization in estuaries. However, little research has been conducted to compare the macrofauna associated with riprap‐sill and riprap‐hardened shorelines. Density and diversity of fish and blue crabs Callinectes sapidus were compared via weekly sampling along a riprap‐sill shoreline, a riprap shoreline, and a shoreline fringed with smooth cordgrass Spartina alterniflora marsh in the Delaware Coastal Bays during summer 2010. Seining was conducted to quantitatively sample the shore zone and shallow subtidal regions, and minnow traps were used to determine the presence or absence of fishes in the mid‐ to upper‐intertidal zone of each shoreline type. Temporally persistent differences in macrofaunal density and diversity were evident among the three shoreline types. In terms of fish density and diversity metrics, riprap‐sill was more similar to the smooth cordgrass shoreline than to the traditional riprap shoreline. These results provide evidence for the biological advantage of riprap‐sill over traditional riprap as a shoreline modification structure; spatial confirmation by further studies at different locations is warranted. Received October 27, 2015; accepted March 15, 2016 Published online June 21, 2016

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a b s t r a c tSea ice decline is anticipated to increase human access to the Arctic Ocean allowing for offshore oil and gas development in once inaccessible areas. Given the potential negative consequences of an oil spill on marine wildlife populations in the Arctic, it is important to understand the magnitude of impact a large spill could have on wildlife to inform response planning efforts. In this study we simulated oil spills that released 25,000 barrels of oil for 30 days in autumn originating from two sites in the Chukchi Sea (one in Russia and one in the U.S.) and tracked the distribution of oil for 76 days. We then determined the potential impact such a spill might have on polar bears (Ursus maritimus) and their habitat by overlapping spills with maps of polar bear habitat and movement trajectories. Only a small proportion (1 e10%) of high-value polar bear sea ice habitat was directly affected by oil sufficient to impact bears. However, 27e38% of polar bears in the region were potentially exposed to oil. Oil consistently had the highest probability of reaching Wrangel and Herald islands, important areas of denning and summer terrestrial habitat. Oil did not reach polar bears until approximately 3 weeks after the spills. Our study found the potential for significant impacts to polar bears under a worst case discharge scenario, but suggests that there is a window of time where effective containment efforts could minimize exposure to bears. Our study provides a framework for wildlife managers and planners to assess the level of response that would be required to treat exposed wildlife and where spill response equipment might be best stationed. While the size of spill we simulated has a low probability of occurring, it provides an upper limit for planners to consider when crafting response plans.Published by Elsevier Ltd.