Recruitment Dynamics and Nursery Habitat Use of Fishes in Matagorda Bay, Texas
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Date
2022-08-31
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Abstract
Recruitment to and use of seagrass and saltmarsh habitats by post-settlement fishes has been linked to biological and physicochemical properties of the estuary during settlement and early life periods. The purpose of this study was to assess variation in abundance (density) and diversity of post-settlement fishes using these habitats in Matagorda Bay, a subtropical estuary on the Gulf Coast of Texas, and then determine environmental conditions that correspond to increased density and diversity. To do this, post-settlement fishes were sampled seasonally from each habitat in 2020 and 2021 using an epibenthic sled. Seagrass consistently had higher abundances of post-settlement fishes than saltmarsh, and the density of fishes in both habitats differed by season and year. Diverse assemblages were present in both seagrass and saltmarsh habitat and both diversity measures evaluated at the family level (taxonomic richness [TF] and Shannon diversity [H’]) differed significantly between seasons and years. Community structure also differed significantly between seagrass and saltmarsh habitat, and dissimilarity was influenced principally by shifts in families of fishes that use these nursery habitats seasonally (Sciaenidae [drums and croakers], Paralichthyidae [sand flounders], Gerreidae [mojarras], Syngnathidae [pipefishes and seahorses]) and highly abundant resident taxa that occur throughout the year (Gobiidae [gobies], Sparidae [porgies], and Fundulidae [killifishes]). Density, TF, and H’ were all significantly related to habitat type, dissolved oxygen, and distance to tidal pass. Density and H’ were related to salinity, year, and time of day, while density and TF were related to water temperature and turbidity. Lastly, both diversity indices were significantly related to tide height. Further study of species in the family Sciaenidae revealed species-specific differences in nursery habitat use that help explain observed shifts in density and diversity at the family level. This study identified conditions and areas of the estuary that support abundant and diverse assemblages of post-settlement fishes, and findings from this study will serve as a foundation for monitoring the health and stability of seagrass and saltmarsh nurseries in Matagorda Bay.
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Marine ecology, fish, fisheries, nursery habitat, recruitment, seagrass, Matagorda Bay