Patterns of habitat suitability and abundance trends of current and candidate coastal fish species of concern in Louisiana

Louisiana’s estuaries and coastal waters play an important role in providing habitat for several estuarine-dependent species and also serve as a nursery for the juveniles of several other species. The current rate of land loss in Louisiana and the decline of estuarine-dependent species force us to improve our understanding of the recruitment of these species into Louisiana’s estuaries. Habitat suitabilities were developed for several fish species of concern (SOC) and other estuarine-dependent species across three environmental gradients, abundance patterns were developed for seasons, five-year intervals, and coastal study areas (CSAs). Chi-square analyses and ANOVAs were then used to test for differences in the suitability patterns and abundance patterns, respectively. The pipefish species, chain pipefish, Syngnathus louisianae (SOC) and gulf pipefish, Syngnathus scovelli, had significantly different suitability patterns for all three environmental variables. Chain pipefish suitability patterns were significantly different for all three variables, whereas, gulf pipefish only had strong patterns for salinity and Secchi depth. The pipefishes also had different temporal and spatial abundance patterns. The two goby species, violet goby, Gobioides broussonnetii (SOC) and sharptail goby, Gobionellus hastatus, had similar suitability patterns for all three environmental variables, but for sharptail goby did not have a strong salinity suitability pattern. They also had similar seasonal abundance patterns with peaks during the spring months. The three SOC fundulids, diamond killifish, Adinia xenica, bayou killifish, Fundulus pulvereus, and saltmarsh topminnow, Fundulus jenkinsi, shared similar, strong patterns of suitability for temperature and salinity. For Secchi depth, only diamond killifish and bayou killifish had strong suitability patterns. All three species also shared seasonal abundance patterns with peaks in the winter, and spatial abundance patterns with peaks in the central CSAs. The two candidate SOCs, Atlantic threadfin, Polydactylus octonemus and southern puffer, Sphoeroides nephelus, were chosen for further analyses based on their declining annual abundances. They did not have any similar temporal or spatial abundance patterns. The two species had strong suitability patterns for all three environmental variables; however, they did not share any similar patterns. The strong suitability patterns suggest that some of the environmental variables effect habitat selection for several of these species