Publications by authors named "Jens Hegg"

Human activities have significantly altered coastal ecosystems worldwide. The phenomenon of shifting baselines syndrome (SBS) complicates our understanding of these changes, masking the true scale of human impacts. This study investigates the long-term ecological effects of anthropogenic activities on New Zealand's coastal ecosystems over 800 years using fish otolith microchemical profiling and dynamic time warping across an entire stock unit.

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The migration of Pacific salmon is an important part of functioning freshwater ecosystems, but as populations have decreased and ecological conditions have changed, so have migration patterns. Understanding how the environment, and human impacts, change salmon migration behavior requires observing migration at small temporal and spatial scales across large geographic areas. Studying these detailed fish movements is particularly important for one threatened population of Chinook salmon in the Snake River of Idaho whose juvenile behavior may be rapidly evolving in response to dams and anthropogenic impacts.

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Animal migrations provide important ecological functions and can allow for increased biodiversity through habitat and niche diversification. However, aquatic migrations in general, and those of the world's largest fish in particular, are imperiled worldwide and are often poorly understood. Several species of large Amazonian catfish carry out some of the longest freshwater fish migrations in the world, travelling from the Amazon River estuary to the Andes foothills.

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Human disturbances to ecosystems have created challenges to populations worldwide, forcing them to respond phenotypically in ways that increase their fitness under current conditions. One approach to examining population responses to disturbance in species with complex life histories is to study species that exhibit spatial patterns in their phenotypic response across populations or demes. In this study, we investigate a threatened population of fall chinook salmon (Oncorhynchus tshawytscha) in the Snake River of Idaho, in which a significant fraction of the juvenile population have been shown to exhibit a yearling out-migration strategy which had not previously been thought to exist.

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