Variações ecomorfológicas intraespecíficas de Atherinella brasiliensis (Atheriniformes: Atherinopsidae) em ecossistemas dulcícola e salobros

Abstract

Ecomorphological analyzes are study tools of the resources, interactions and biotic and abiotic factors influence on the body shape of individuals. According to the ecomorphological concept, it is possible to make inferences of the environment influence and its resources from specimens shape characteristics. Studies on intraspecific morphological variations in fish indicate that they may be the result of niche differences among populations, favoring their adaptation according to environmental changes. The kingfish, Atherinella brasiliensis, has wide distribution throughout the South Atlantic and is resident of estuarine environments. Specimens of this species were often caught in Sitios Novos reservoir (Caucaia CE), 33km from the coast. From this, this study aimed to compare the ecomorphological characteristics of A. brasiliensis populations from Sítios Novos reservoir (Caucaia CE) and from Taíba (São Gonçalo do Amarante CE) and Cauípe (Caucaia CE) lagoons, two coastal lagoons where the species also occurs. This study hypothesis was: "Sítios Novos reservoir A. brasiliensis population has distinct morphological structure in relation to Taíba and Cauípe lagoons A. brasiliensis populations". Collects of A. brasiliensis specimens were carried out between March and September 2014, through castnet bids and beach seines. Subsequently, captured specimens were fixed in 10% formalin and preserved in 70% alcohol. Twenty one morphometric measurements were performed on 20 specimens of each studied ecosystem. From these measurements, 22 ecomorphological indexes were calculated. A Principal Component Analysis (PCA) identified trends in A. brasiliensis populations morphology and a Permutational Multivariate Analysis of Variance (PERMANOVA) indicated that Sítios Novos reservoir population significantly differed from coastal lagoons populations. Sítios Novos reservoir population individuals presented more protractile mouths and more developed pectoral, pelvic and caudal fins while coastal lagoons populations individuals presented larger eyes and heads, more depressed bodies, and more developed pectoral, pelvic and dorsal fins. Ecomorphological differences among analyzed A. brasiliensis populations suggests that a number of environmental variables affect them in each studied ecosystem.