Ictiofauna estuarina do Nordeste do Brasil: variabilidade espacial e indicadores funcionais

Abstract

Coastal zones are areas that have important ecological functions and serve as a link between marine and terrestrial ecosystems. This peculiarity is due to numerous characteristics, such as salinity variability, support for the reproduction of species, different sources of food, and high availability of nutrients, making them complex environments and of extreme importance for the life cycle of marine species. Among the tropical coastal ecosystems, estuaries and their mangroves are dynamic areas that play important roles, whether on the socioeconomic, as a source of income and food for the communities that live nearby, or on the environmental aspect (e.g. nursing areas, protection against floods and storms). The diversity of species can vary on a local scale or between regions in a geographical scale. Physical and biological aspects can influence these patterns as well as the interaction among its components, causing differences within and among communities. Several tools can be used to understand the patterns of species distribution and function. Despite the existence of studies on the biodiversity of estuarine fish fauna in Brazil, these are generally in a low number and isolated in the northeastern region, not reflecting the number of estuarine environments along the coast of the region. It indicates a deficiency in the knowledge of their ichthyofaunal composition. This study has the general objective of understanding the geographic patterns of the estuarine ichthyofauna of Northeastern Brazil, through the knowledge of the structural aspects of the assemblages and functional indices. The first chapter provides a synthesis of information on the estuarine ichthyofauna of six of the most important estuaries of Pernambuco based on samples between the years 2000 and 2018 totaling 198 fish species and correlating with abiotic data to better understand their geographical patterns. Among these species, 80% were designated as marine migrants and stragglers and 70% as zoobenthivores and piscivores. The second chapter provides a synthesis of the available information on the estuarine ichthyofauna of Northeast Brazil, identifying and characterizing geographical patterns, also analyzing taxonomic similarities among the 45 studied estuaries totaling 339 fish species. Marine migrants and stragglers species were 77% of the total number of species and 72% were considered zoobenthivorous and piscivorous. In both articles, each species was designated a category of the regional (ICMbio) and/or international (IUCN) endangered species list.