Non-native regal demoiselle, Neopomacentrus cyanomos, presence, abundance, and habitat factors in the North-Central Gulf of Mexico

Remotely operated vehicle (ROV) surveys were conducted at reef sites in the northern Gulf of Mexico (nGOM) during 2018–2019. Artificial (AR = 63) and natural (NR = 139) reefs were located in a 2 × 10 5 km 2 area south of Mobile, AL to Destin, FL at depths of 13–75 m. We observed a total of 5371 damselfishes (Family: Pomacentridae) belonging to eight taxa. The non-native regal demoiselle (regal), Neopomacentrus cyanomos , was present at 30.2% of ARs but only 1.4% of NRs with densities ranging from 0.19 to 18.11 fish per 100 m 2 . Regals were most dense at shallow ARs, comprising 53% of the damselfish community, and least dense at deeper reefs comprising < 1% of observed damselfishes. Results from generalized linear mixed models (GLMMs) indicated the interaction among reef type, complexity, relief, and depth had a significant effect on regal density but that reef type (36%) and the interaction between reef type and depth (25%) explained the greatest proportions of variance in the data (partial η 2 ) while the interaction among all four main effects explained only a small amount (2%). Our data indicate regals prefer shallow artificial structures with low complexity but can occupy deeper reefs, including NRs, despite less-favorable conditions. Our data document the persistence of regals in the nGOM and identify habitat factors that are significantly related to their presence and density in the region. However, the dynamics controlling their distribution are still uncertain and potential negative impacts on native reef fish communities remain unclear.