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Variability in space use among conspecifics can emerge from foraging strategies that track available resources, especially in riverscapes that promote high synchrony between prey pulses and consumers. Projected changes in riverscape hydrological regimes due to water management and climate change accentuate the need to understand the natural variability in animal space use and its implications for population dynamics and ecosystem function. Here, we used long-term tracking of Common Snook (Centropomus undecimalis) movement and trophic dynamics in the Shark River, Everglades National Park from 2012 to 2023 to test how specialization in the space use of individuals (i.e., Eadj) changes seasonally, how it is influenced by yearly hydrological conditions, and its relationship to the between individual trophic niche. Snook exhibited seasonal variability in space use, with maximum individual specialization (high dissimilarity) in the wet season. The degree of individual specialization increased over the years in association with greater marsh flooding duration, which produced important subsidies. Also, there were threshold responses of individual space use specialization as a function of floodplain conditions. Greater specialization in space use results in a decrease in snook trophic niche size. These results show how hydrological regimes in riverscapes influence individual specialization of resource use (both space and prey), providing insight into how forecasted hydroclimatic scenarios may shape habitat selection processes and the trophic dynamics of mobile consumers.
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Effects of hydrology on the movements of a large-bodied predator in a managed freshwater marsh
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.
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- PAR ID:
- 10311132
- Date Published:
- Journal Name:
- Hydrobiologia
- ISSN:
- 0018-8158
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1007/s10750-021-04764-x
