Bacterial communities on the gills of bonefish ( Albula vulpes ) in the Florida Keys and The Bahamas show spatial structure and differential abundance of disease-associated bacteria

The Caribbean bonefish species Albula vulpes is an economically important nearshore marine sport fish that has notably declined in the Florida Keys over the past 20–30 years. The reasons for this decline are unclear, although habitat loss, water quality reductions, climate change, and other environmental drivers likely play a role. Infectious disease can also cause precipitous species-specific declines in wildlife populations, but virtually nothing is known about infection in bonefish. We analyzed communities of bacteria on the gills of bonefish from the Florida Keys, where declines are pronounced, and the islands of Eleuthera and Inagua in The Bahamas, where no such declines have been recorded. Bacterial community composition varied significantly among island location (Keys, Eleuthera, Inagua) and among sites within island locations (e.g., tidal creeks, coves, inlets). Seventeen times more bacterial taxa were over-represented in the Florida Keys than in The Bahamas, and several bacterial genera over-represented in the Florida Keys have been linked to environmental contamination and disease (e.g., Corynebacterium ; Acholeplasma ; Staphylococcus ; and Streptococcus ). These results show that gill bacterial community signatures may prove useful for investigating bonefish spatial ecology and that communities of microbes on bonefish gills contain differentially abundant and potentially pathogenic bacteria that covary with the overall “health” of the population.