Geometric morphology as an alternative for measuring the diversity of fish assemblages

Biological diversity can be measured using ecological, taxonomic and functional indices, although numerous studies have concluded that organism morphology can be also a source for computing diversity indices. In the present study, we characterized fish morphology using geometric morphology, which included body shape landmarks as well as the morphology of fins, and we computed the correlation among ecological, taxonomic, functional and morphological indices (including a new index defined here called “morphological richness”). Morphological indices were calculated both from abundance data and presence/absence data. To carry out this study, thirteen fish assemblages of two different areas of the Catalan coast (north-western Mediterranean) were analyzed. The data was sampled by commercial fishing vessels using trammel nets. The results clearly indicated that each type of morphological index is related to one dimension of the biodiversity space. Furthermore, we demonstrated that presence/absence data provided the similar results as abundance data when using morphological indices, opening the possibility to analyze the evolution of fish assemblages over time from species checklists collected in experimental surveys from the late XIX century to the present.