Detection of Shifts in Coral Reef Fish Assemblage Structure Over 50 Years at Reefs of New Providence Island, the Bahamas Highlight the Value of the Academy of Natural Sciences' Collections in a Changing World

Abstract

Natural history collections contain historical records that present snapshots of organisms and communities, and are now more important than ever in the face of rapidly changing environments. The world's largest collection of fishes from The Bahamas is housed at The Academy of Natural Sciences, Philadelphia. These vast Bahamas holdings primarily resulted from the collecting efforts of James Böhlke and Charles Chaplin in the 1950s–1970s. One of the many ways these historical records have been used since their collection is as baseline data for coral reef sites that were revisited decades later to answer questions about changes in coral reef fish community structure through time. Analyses of data collected from resurveys conducted in 2006 and 2010 provided evidence for a relative increase in the abundance of individuals belonging to different trophic groups and families; particularly, a relative increase in herbivores (mainly parrotfishes) and a relative decrease in planktivores. Furthermore, an interesting inverse trend was detected between two nocturnal groups of fishes, where the larger-bodied sqnirrelfishes increased while the smaller-bodied cardinalfishes decreased in relative abundance. These significant differences across trophic groups and families are consistent with the effects of a degraded reef habitat characterized by increased algal cover and fewer shelter spaces. Overall, these resurvey results suggest that neither the coral nor reef-fish communities reflect ‘baseline’ conditions. Continued monitoring of these assemblages using comparative data from multiple replicate samples across time periods will be needed to detect their further change or stabilization.