Stage-specific variability in habitat associations of juvenile red drum across a latitudinal gradient
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Inter-Research 2016. Long-term fisheries independent data (2000-2014) from bag seine surveys were used to characterize fish-habitat relationships for red drum Sciaenops ocellatus at 2 critical life stages during the first year of life: post-settlement (October to December) and early juvenile (overwintering, January to March). Relationships between environmental variables and red drum abundance were examined in 3 estuaries (Galveston Bay, Aransas-Corpus Bay, and Laguna Madre, Texas, USA) along a latitudinal gradient using generalized additive models. Temporal factors were among the most important predictor variables for both life stages, with month and/or year retained in each model. In addition to temporal variability, abundance of post-settlement and early juvenile red drum was influenced by both physicochemical conditions (temperature and salinity) and aquatic vegetation (seagrass and salt marsh coverage). Although fish-habitat relationships were often similar across the 3 estuaries, the relative importance of abiotic and biotic factors to red drum distribution and abundance varied among estuaries and life stages. Likewise, habitat relationships for post-settlement and early juvenile red drum were influenced by variability in habitat availability among estuaries, with abundance at both life stages positively associated with seagrass coverage in seagrass-limited systems and negatively associated in systems where seagrass was more abundant. This study clearly demonstrates that fish-habitat relationships for red drum are life stage-, time- and estuary-specific, and therefore, habitat suitability models that account for such variability are needed to effectively identify and conserve important estuarine nursery areas.
