MEPS 598:113-129 (2018)  -  DOI: https://doi.org/10.3354/meps12596

ABSTRACT: Guilds are defined as polyphyletic species groups delineated by specific attributes selected by the organizer. Functional guilds combine species on the basis of niches and ecological roles, whereas structural guilds combine species based on the use of a particular resource. Guilds can be substituted for individual species in an analysis, allowing for insight based on ecological questions with reduced variance from taxonomic differences. In this case study, we examined guilds of fishes over decades based on reproductive characteristics, and again on origin relative to the system, in an estuary in southern New Jersey, USA. These guilds were used in principal components analyses of the recruitment to an estuary of groups of fishes based on spawning origin or life history characteristics. In both cases, use of the guilds resulted in more explained variation than did use of a full species assemblage. Both 8-class and 12-class reproductive guild clusters explained more than 50% of the total variance on the first 2 eigenaxes while displaying similar trends across time in comparison with the full species assemblage. Use of an abundance-based species assemblage also resulted in more explained variation than use of the full species assemblage. Overall, reproductive guilds more accurately reflected assemblage changes within the Mullica River-Great Bay ecosystem than origin guilds. Rare species did not contribute to a long-term change in assemblage. The sensitivity of results to guild construction might differ for estuaries that are at the margins of their respective oceanographic province.

KEY WORDS: Guilds · Fish · Assemblage · Estuary · Long-term · Time-series