Frontiers in Marine Science (Nov 2015)
Seasonal variability of morphospaces in a subtropical fish assemblage
Abstract
Morphological characters of fishes are essential to evaluate the functional structure of assemblages, being morphological differences indicative of distinct ecological and adaptive strategies. The ecomorphology using morphospaces analyzes the structure of a fish assemblage through the values of intervals between homologous points positioned in anatomical structures of organisms phylogenetically related. These intervals can be quantified by morphogeometric and multivariate analyses. Seasonally during 2013-2014, standardized images were obtained from fishes sampled in Araça Bay, São Sebastião District, Brazil, using nine fishing gears which were grouped to verify the species occurrence variation. Qualitative approach (presence/absence data) was used to carry out morphological analyses. A total of 27 landmarks and semilandmarks with anatomical, ecological and taxonomical meaning were positioned in species images of the left profile. Consensus figures were made embedding the intraspecific variability. Uniform components of the shape variation (RWs) were generated. To build morphospaces, the first eight RWs were considered (explain more than 95% of the total morphological variability) and were defined using Convex Hull. The RWs were also used to calculate the Morphological Richness (MR), Morphological Disparity (MD) and Morphogeometric Index (EMI). The MD indicates the morphospace size and showed greater values in summer (0.051) and winter (0.047) as MR, related to the higher number of species (MRsummer=7.93; MRwinter=8.65). During all the year, the Araça Bay presents high diversity of fishes. Nevertheless, winter and summer seasons reached the highest diversity, periods when horizontal mobile fishes with elongated shapes arrive to the region, implying an increase of morphological diversity and shape’s redundancy (represented by the lowest values of EMI: winter=0.120; summer=0.123).
Keywords
