Hurricane events facilitate the establishment of nonnative invertebrate species in harbors

Abstract

AbstractThe coastal location and shallow depths of harbors suggest that fouling communities will be greatly affected by extreme weather events. Within fouling communities, ascidians are conspicuous animals and their sessile nature makes them ideal targets to assess community resilience. We established ascidian diversity and abundance at eighteen harbors and marinas along the coast of North Carolina (United States) a year after Hurricane Florence landfall in 2018 (post-hurricane) and compared results with those obtained in 2014 (pre-hurricane). The distribution and community structure of native and introduced ascidians were analyzed using presence-absence and relative abundance similarity matrices. Both geographic location (North vs. South) and distance between harbors had a significant effect on ascidian community composition. When compared with pre-hurricane data, a decrease in the number of native species and an increase of introduced and cryptogenic species was noted, although these trends were only statistically significant for the number of introduced species based on presence-absence data. Monthly photo transects spanning pre- and post-hurricane periods to monitor the ascidian community at the harbor located where the hurricane made landfall, revealed that all but one species disappeared from the docks after the hurricane. Recolonization occurred slowly, and one year later, only two non-native species were present. Further, we report the arrival of the globally introduced speciesStyela canopusandDistaplia listerianumin North Carolina. This study significantly advances our understanding of the impact of hurricanes on fouling communities inhabiting harbors and the speed of natural recovery.