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Wetlands are dynamic environments where aquatic organisms are affected by both predictable and unpredictable changes in hydrology. Understanding how abundant large-bodied predators respond to these changes is especially important in context of wetland restoration. We used satellite telemetry to investigate how individual (e.g., sex, size, body condition) and environmental factors influenced movement behaviors of American Alligators [Alligator mississippiensis (Daudin, 1801)] in a managed freshwater marsh ecosystem of the Florida Everglades. We quantified space use, movement activity, and habitat selection of animals (n = 18) across hydrological seasons and the breeding period and performed stable isotope analyses to infer seasonal dietary changes. Though individual animals did not change space use across seasons, movement activity was lower for some individuals and δ15 Nitrogen isotopic values were higher in the dry season possibly reflecting greater foraging opportunities when marsh dry down concentrates prey. Alligators may be using canals as foraging sites which have abundant prey year-round and shallow sawgrass habitats as spots for basking. Based on our findings, ongoing restoration of water inflow will likely change the distribution and movement behavior of alligators. [ABSTRACT FROM AUTHOR]

Predicting the responses of animals to environmental changes is a fundamental goal of ecology and is necessary for conservation and management of species. While most studies focus on relatively gradual changes, extreme events may have lasting impacts on populations. Animals respond to major disturbances such as hurricanes by seeking shelter, migrating, or they may fail to respond appropriately. We assessed the effects of Hurricane Irma in 2017 on the behavior and survival of juvenile bull sharks (Carcharhinus leucas) within a nursery of the Florida coastal Everglades using long-term acoustic telemetry monitoring. Most of our tagged sharks (n = 14) attempted to leave the shallow waters of the Shark River Estuary before the hurricane strike, but individuals varied in the timing and success of their movements. Eight bull sharks left within hours or days before the hurricane, but three left more than a week in advance. Nine of 11 bull sharks (~ 82%) eventually returned to the array within weeks or months of the storm. Six of these returning individuals were detected in a different coastal array in nearshore waters ca. 80 km away from the mouth of the estuary during their absence. The remaining three bull sharks moved downstream relatively late (after the hurricane) and may have died. We used binomial generalized linear mixed models to estimate the probability of presence within the array as a function of several environmental variables. Departure from the array was predicted by declining barometric pressure, increasing rate of change in pressure, and potentially fluctuations in river stage. Juvenile bull sharks may weigh multiple environmental cues, perceived predation risk, their own physical size, and shifting prey resources when making decisions during and after hurricanes. [ABSTRACT FROM AUTHOR]

How phenotypic plasticity of locomotor performance varies among populations in nature is poorly known. Swimming ability of blacknose dace ( Rhinichthys atratulus) from eight different watersheds had previously been shown to depend upon watershed impervious surface cover (ISC) and stream base-flow. Keeping these populations of stream fish under low flow conditions produced changes in locomotor capacity suggestive of phenotypic plasticity varying among the populations. The present experiments were conducted to better understand the plasticity of swimming performance in dace and how urbanization affects dace biology. Two experimental approaches were used: 1) laboratory training of dace populations at two levels of flow for 6 weeks; and, 2) exploring in situ training by capturing fish from relatively fast and slow reaches of three different streams and comparing their swimming abilities at three different scales. Individual sprint and endurance (modified U) swimming were significantly repeatable across a laboratory training regimen; sprint performance had previously been shown to not be repeatable when dace were held in static water. Both of our approaches suggested that sprint and endurance swimming ability significantly respond to changes in environmental flow. Although there was no evidence for a different magnitude of phenotypic plasticity among populations, urban populations that experience more stochastic flow regimes had more consistent plasticity. Phenotypic plasticity of locomotor performance in response to variable flow appears to be an important characteristic of blacknose dace biology, yet we did not uncover sufficient evidence to suggest that it is under selection in fish adjusting to urban stream habitats. [ABSTRACT FROM AUTHOR]

Many shark populations are in decline around the world, with severe ecological and economic consequences. Fisheries management and marine protected areas (MPAs) have both been heralded as solutions. However, the effectiveness of MPAs alone is questionable, particularly for globally threatened sharks and rays ('elasmobranchs'), with little known about how fisheries management and MPAs interact to conserve these species. Here we use a dedicated global survey of coral reef elasmobranchs to assess 66 fully protected areas embedded within a range of fisheries management regimes across 36 countries. We show that conservation benefits were primarily for reef-associated sharks, which were twice as abundant in fully protected areas compared with areas open to fishing. Conservation benefits were greatest in large protected areas that incorporate distinct reefs. However, the same benefits were not evident for rays or wide-ranging sharks that are both economically and ecologically important while also threatened with extinction. We show that conservation benefits from fully protected areas are close to doubled when embedded within areas of effective fisheries management, highlighting the importance of a mixed management approach of both effective fisheries management and well-designed fully protected areas to conserve tropical elasmobranch assemblages globally., (© 2024. Crown.)