High Site Fidelity and Elevated δ¹⁵N in Bonefish (Albula vulpes) Suggest Localized Wastewater Stress in a Marine National Park

Abstract

Coastal zones are subjected to many anthropogenic stresses that operate on multiple spatial scales. Understanding how these stressors interact with the movement and resource ecology of mobile species is critical for effective conservation and management. Biscayne National Park (BNP) is adjacent to Miami (U.S.) and supports an economically important recreational fishery for bonefish ( Albula vulpes ). Within BNP, the western region is subjected to nutrient loading and seagrass fragmentation from mainland anthropogenic stress. Here we ask, do bonefish show fidelity to regions within Biscayne Bay? And do their movement and residency patterns create intra-population differences in exposure to land-based anthropogenic stresses? We investigated the spatial ecology of bonefish within western and eastern regions in BNP and an adjacent region, upper Florida Keys, to the south, using acoustic telemetry and stable isotope analysis. Our study revealed high site fidelity among bonefish across three regions, with limited inter-regional movement outside of spawning migrations. Stable isotope analysis showed more enriched δ¹⁵N values in west BNP bonefish, suggesting exposure to wastewater-derived nutrient subsidies. And, less enriched δ 13 C in west BNP relative to east BNP potentially due to higher inputs of terrestrial basal resources. These findings indicate that bonefish residency patterns result in differential exposure to land-based stressors that should be considered for management and conservation of BNP ecosystems. Our results highlight the utility of combining movement and resource use data to identify vulnerable subpopulations and inform spatially explicit management strategies in urbanized coastal systems.

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