Virginia Institute of Marine Science
Biodiversity has typically been described in terms of species richness and composition, but theory and growing empirical evidence indicate that the diversity of functional traits, the breadth of evolutionary relationships, and the equitability with which individuals or biomass are distributed among species better characterize patterns and processes within ecosystems. Yet, the advantages of including such data come at the expense of measuring traits, sequencing genes, and counting or weighing individuals, and it remains unclear whether this greater resolution yields substantial benefits in describing diversity. We summarized a decade of high-resolution trawl data from a bimonthly trawl survey to investigate spatial and seasonal patterns of demersal fish diversity in the Chesapeake Bay, USA, with the goal of identifying areas and times of mismatch between different dimensions of diversity, and their response to environmental forcing. We found moderate to strong positive relationships among all metrics of diversity, and that functional and phylogenetic differences were well-reflected in an index derived from taxonomic (Linnaean) hierarchy. Compared with species richness and species diversity, functional, phylogenetic, and taxonomic indices peaked later in the year, which was a consequence of the distribution of biomass among functionally and evolutionarily divergent species. Generalized additive models revealed that spatial, temporal, and environmental variables explained roughly similar proportions of deviance across all aspects of diversity, suggesting that these three factors do not differentially affect the functional and phylogenetic aspects of community structure. We conclude that an index of diversity derived from taxonomic hierarchy served well as a practical surrogate for functional and phylogenetic diversity of the demersal fish community in this system. We also emphasize the importance of evenness in understanding diversity patterns, especially since most ecological communities in nature are dominated by one or few species.
RAOS QUADRATIC ENTROPY; FUNCTIONAL DIVERSITY; PHYLOGENETIC DIVERSITY; SPECIES-DIVERSITY; MEDITERRANEAN SEA; CONTINENTAL-SHELF; FEEDING-HABITS; GROUNDFISH ASSEMBLAGES; COMMUNITY COMPOSITION; GENERAL COEFFICIENT
We thank all current and past ChesMMAP personnel, especially Christopher Bonzek, James Gartland, and the crew of the R/V Bay Eagle, for their diligent work in collecting and maintaining all the survey data used in this study. Support for ChesMMAP was provided by the NOAA Chesapeake Bay Office, the Virginia Environmental Endowment, the U.S. Fish and Wildlife Service, and the Virginia Marine Resources Commission. We thank the staff at the Smithsonian Museum Support Center, especially Jeff Williams and Jerry Finan, and the VIMS Ichthyology Collection for allowing us to measure specimens. We also thank two anonymous reviewers for their comments. This work was supported by the National Science Foundation under Grant No. DEB-1050680 to J. K. Parrish and S. Andelman as part of the Dimensions of Biodiversity Distributed Graduate Seminar. We additionally thank coordinators Christina Maranto and Rachel Sewell-Nesteruk, and seminar participants at other institutions for thoughtful discussion and input. J. S. Lefcheck was supported by NSF 1050680, VA SeaGrant NA10OAR4170085, and the VIMS Dean's Fellowship. This paper is Contribution No. 3332 of the Virginia Institute of Marine Science, College of William & Mary.
Lefcheck, J. S., A. Buchheister, K. M. Laumann, M. A. Stratton, K. L. Sobocinski, S. T. C. Chak, T. R. Clardy, P. L. Reynolds, R. J. Latour, and J. E. Duffy. 2014. Dimensions of biodiversity in Chesapeake Bay demersal fishes: patterns and drivers through space and time. Ecosphere 5(2):14. http://dx.doi.org/10.1890/ES13-00284.1