Coupling telemetry and stable isotope techniques to unravel movement: Snook habitat use across variable nutrient environments

摘要

Habitat selection by organisms can be driven by a number of factors, including the availability of resources. In particular, nutrient enrichment can alter the quality of landscapes, and thus the availability of resources, with implications for consumer movement and habitat use. In coastal ecosystems, eutrophication can affect the production and distribution of resources, and thus the behaviors and space use of consumers. In this study, we coupled acoustic telemetry methods and stable isotope analyses (SIA) to examine the effects of nutrient enrichment on the movement, habitat use, and resource use of Common Snook (Centropomus undecimalis), a valuable recreational fishery, across two neighboring estuarine lake systems of varying trophic state (eutrophic vs. mesotrophic), located in Florida Bay (Florida, USA). Snook had more inter-zone movement events in the mesotrophic system, suggesting higher mobility. More specifically, increased inter-zone movement events were observed in the upstream and middle zones of the mesotrophic system where salinity and submerged aquatic vegetation was lower, and Chlorophyll a levels were higher. We also observed longer movement event durations in the eutrophic system, suggesting higher residency and a trend for event durations to vary across zones. Based on delta N-15, delta C-13 and delta S-34 analyses, we determined that although Snook had similar trophic levels across systems, eutrophic Snook relied on a greater diversity of basal sources relative to mesotrophic Snook. When relating movement to trophic metrics, we found the relationship to be zone-dependent, with higher trophic level Snook showing more movements into the middle and downstream zones, but less movements into the upstream zones. These findings highlight the value of cross-site comparisons that pair movement and trophic measurements to improve our understanding of how animals select habitats under varying environmental conditions and production regimes.