Neritic larval fish assemblages across the Texas shelf in the northwestern Gulf of Mexico following Hurricane Harvey

Abstract

Fall is an important time of year for fish recruitment in the Gulf of Mexico, with many commercially and recreationally important species spawning during this period. Changes in temperature and salinity regimes through seasonally abnormal freshwater input may change spawning patterns and displace larvae. Such an event occurred off the coast of Galveston Bay, Texas, when a freshwater flood plume formed from unprecedented rainfall related to Hurricane Harvey at the end of August 2017. This study investigated the effects of a large-scale flood plume on larval fish assemblages, collected at nearshore and shelf zones 1 and 2 months after Hurricane Harvey. Samples from 2017 were compared to historical datasets collected by NOAA Fisheries in September (2000–2004 and 2006–2016) and October (2000–2012). Evidence of lowered water temperature and salinity was found in both September and October 2017. Larval community composition changed along cross-shelf gradients and with increasing distance from shore. We also found evidence of 2017 assemblages differing from historical data, with the September 2017 assemblage more closely resembling those from October historical samples. Observed differences in 2017 assemblages were most likely explained by an earlier onset in fall sciaenid spawning, suggesting that decreases in water temperature occurring during hurricanes have the potential to alter fish spawning patterns.