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A comprehensive chronic toxicity and carcinogenicity study was conducted on a series of Aroclors (1016, 1242, 1254, and 1260). Each Aroclor was assessed at multiple dietary concentrations, ranging from 25 to 200 ppm, for 24 months in male and female Sprague-Dawley rats. Liver toxicity was indicated by elevated serum enzyme activity (AST, ALT, and GGT), elevated serum cholesterol concentration, decreases in hematologic parameters (RBC, Hb, and Hct), hepatocellular hypertrophy, an increased incidence of altered hepatocellular foci, and an increased incidence of hepatocellular neoplasms (primarily adenomas). Liver toxicity was distinctly more severe in females than in males. The incidence of hepatocellular neoplasms was highly sex-dependent (females >> males), differed between Aroclor mixtures and, for females, increased with dose and followed the general incidence pattern of Aroclor 1254 > Aroclor 1260 approximately Aroclor 1242 > Aroclor 1016. A significant response (p < 0.05) in males was seen only for the high dose of Aroclor 1260. A small increase in the incidence of thyroid gland follicular cell adenomas was noted in males for Aroclors 1242, 1254, and 1260, with the incidence being uniform across dose groups and Aroclor mixtures. For females, increased survival relative to controls was observed for all Aroclor treatment groups. A significantly decreased trend in the incidence of mammary gland neoplasms compared to control was also noted for females receiving Aroclors 1242, 1254, and 1260.

Shoreline modifications, such as bulkheads, riprap, and overwater structures, have altered many of the natural habitats in nearshore urbanized areas surrounding coastal cities, including those in Puget Sound, Washington. The effects of such structures on ecological processes are poorly known, especially those impacting juvenile salmonids Oncorhynchus spp. The goal of our study was to compare the relative abundance and behavior of juvenile salmonids and other fishes along various modified and undeveloped shoreline types. We used enclosure nets and snorkel surveys to sample fishes during high tides in areas adjacent to shore at five main habitat types: cobble beach, sand beach, riprap extending into the upper intertidal zone, deep riprap extending into the subtidal zone, and the edge of overwater structures. Bottomdwelling fishes exhibited the only significant differences in density among cobble beach, sand beach, and riprap that extended into the upper intertidal zone. This suggests that substrate type and slope are important influences on fish densities when shoreline modifications only extend into the upper intertidal zone. Differences in pelagic fish density and behavior were more evident when shoreline modifications extended into shallow subtidal waters, truncating the shallow-water zone and creating deep water at the shoreline. We typically found higher fish densities, larger schools of salmon, and fewer terrestrial riparian insects in salmon diets at these sites. Juvenile salmonids avoided swimming beneath overwater structures, whereas surfperch (family Embiotocidae), crabs (infraorder Brachyura), and sculpins (family Cottidae) were observed beneath or adjacent to pilings. Overall, our results indicate that shoreline modifications have the greatest effect on nearshore fish assemblages when the alterations extend from the supratidal zone into the subtidal zone. Our data suggest that the differences in fish behavior and usage between modified and unmodified shorelines were caused by physical and biological effects of the modifications, such as changes in water depth, slope, substrate, and shoreline vegetation.

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Summary Nearshore ecosystems are increasingly recognized as critical habitats for fish of cultural, ecological and economic significance. These ecosystems are often densely inhabited by juvenile fish, highly productive and refuges from predation, leading ecologists to characterize them as nurseries. However, nearshore ecosystems are being transformed globally to support demands of growing coastal populations. Many shorelines are modified by armouring (e.g. seawalls, riprap) that minimizes erosion, and overwater structures (e.g. piers, docks) that facilitate waterfront use. These modifications affect the ecology of nearshore systems by restructuring, eliminating and shading shallow waters. Here, we review literature examining effects of armouring and overwater structures on coastal and estuarine fishes, and discuss how research and management can coordinate to minimize negative effects. Along armoured shorelines, fish assemblages differed from unarmoured sites, fish consumed less epibenthic and terrestrial prey, beach spawning was less successful and fish were larger. Under large overwater structures, visually oriented fish were less abundant and they fed less. Shade from overwater structures also interrupted localized movements of migratory fish. Thus, shoreline modifications impaired habitats by limiting feeding, reproduction, ontogenetic habitat shifts from shallow to deeper waters and connectivity. Research suggests that restoring shallow waters and substrate complexity, and minimizing shading underneath overwater structures, can rehabilitate habitats compromised by shoreline modifications. Synthesis and applications. Shoreline armouring and overwater structures often compromise fish habitats. These threats to nearshore fish habitats will become more severe as growing coastal populations and rising sea levels increase demands for shoreline infrastructure. Our ability to assess and rehabilitate nearshore fish habitats along modified shorelines will be enhanced by: focusing research attention on metrics that directly indicate fish habitat quality; implementing and evaluating shoreline features that repair compromised habitat functions within human‐use constraints; collating natural history knowledge of nearshore ecosystems; and embracing the socio‐ecological nature of habitat improvements by educating the public about conservation efforts and fostering appreciation of local nearshore ecosystems. Actions to reduce impacts of shoreline modifications on fish are particularly feasible when they align with societal goals, such as improving flood protection and providing spaces that facilitate recreation, education, and connections between people and nature.

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Human population growth and accelerating coastal development have been the drivers for unprecedented construction of artificial structures along shorelines globally. Construction has been recently amplified by societal responses to reduce flood and erosion risks from rising sea levels and more extreme storms resulting from climate change. Such structures, leading to highly modified shorelines, deliver societal benefits, but they also create significant socioeconomic and environmental challenges. The planning, design and deployment of these coastal structures should aim to provide multiple goals through the application of ecoengineering to shoreline development. Such developments should be designed and built with the overarching objective of reducing negative impacts on nature, using hard, soft and hybrid ecological engineering approaches. The design of ecologically sensitive shorelines should be context-dependent and combine engineering, environmental and socioeconomic considerations. The costs and benefits of ecoengineered shoreline design options should be considered across all three of these disciplinary domains when setting objectives, informing plans for their subsequent maintenance and management and ultimately monitoring and evaluating their success. To date, successful ecoengineered shoreline projects have engaged with multiple stakeholders (e.g. architects, engineers, ecologists, coastal/port managers and the general public) during their conception and construction, but few have evaluated engineering, ecological and socioeconomic outcomes in a comprehensive manner. Increasing global awareness of climate change impacts (increased frequency or magnitude of extreme weather events and sea level rise), coupled with future predictions for coastal development (due to population growth leading to urban development and renewal, land reclamation and establishment of renewable energy infrastructure in the sea) will increase the demand for adaptive techniques to protect coastlines. In this review, we present an overview of current ecoengineered shoreline design options, the drivers and constraints that influence implementation and factors to consider when evaluating the success of such ecologically engineered shorelines.