Abstract
The assemblage and functional structure of the fish fauna of the Maracaípe River, municipality of Ipojuca - PE, was characterized by monthly beach trawls carried out from March of 2012 to February of 2013. A beach trawl net (picaré) was used at three different points of the estuary (EST 1, EST 2 and EST 3) during day and night trawls. The captured specimens were measured and weighed in the laboratory, identified and separated into use and trophic guilds using appropriate literature. Abiotic variables (temperature, salinity, dissolved oxygen, pH, turbidity and chlorophyll-a) were analyzed as for differences between day periods (night and day) and seasons (dry and rainy), and correlated to fish abundance. No difference was detected between day periods (p>0.07 for all variables), but they differed between seasons for most variables (pâ"°¤0.02), and between sampling points only for dissolved oxygen (p=0.03). In one year of collection, 11,513 specimens were captured, belonging to 92 species, 38 families and 15 orders. Gerreidae, Atherinopsidae, Clupeidae, Gobiidae and Hemiramphidae were responsible for 82.9% of the total abundance. The estuary of the Maracaípe River presents a rich ichthyofauna, but with the quantitative predominance of seven species (Atherinella brasiliensis, Eucinostomus argenteus, E. melanopterus, Ulaema lefroyi, Lile piquitinga, Ctenogobius boleosoma and Hyporhamphus unifasciatus). In the estuary, six species classified as vulnerable on the IUCN Endangered Species List were reported. The estuary presents a high diversity of species, most of them marine, carnivorous, and opportunistic, showing the high resilience of this environment. The predominance of juvenile fish underscores the importance of the Maracaípe River estuary for the maintenance of population stocks of coastal species, demonstrating the urgent demand of management of this environment.
Highlights
Estuaries are highly productive environments, which favors their use by fish, mainly in their early stages of life, whether they are resident or from different coastal environments, where they find shelter against predators, abundant food and calm waters for reproduction (Able et al, 2010; Barbieri et al, 2014)
Fishes represent most of the nektonic species found in estuaries, being of high ecological importance for their role either by transferring energy to higher trophic levels, or by switching energy to neighboring environments through species moving between different coastal environments (Potter et al, 2011)
Abiotic variables did not differ between periods of day (p>0.07 for all variables) but presented significant differences between seasons for all variables, except for chlorophyll-a
Summary
Estuaries are highly productive environments, which favors their use by fish, mainly in their early stages of life, whether they are resident or from different coastal environments, where they find shelter against predators, abundant food and calm waters for reproduction (Able et al, 2010; Barbieri et al, 2014). As transitional ecosystems between rivers and the sea, estuarine waters are subject to spatial and temporal variations in abiotic parameters, such as temperature, salinity, pH, dissolved oxygen and turbidity. These occur between day and night, throughout the year and between the dry and rainy seasons, according to the variation of the continental water intake (Whitfield and Elliott, 2011). These variations determine the estuarine ichthyofauna, composed of species that use or depend on this environment for some periods or all its life cycle (Elliott and Quintino, 2007). In studies of the distribution and use of estuaries by fish assemblages, in addition to the analysis of the taxonomic diversity found in this environment, the approach of functional guilds in its characterization has been increasingly used, enabling comparative analyses with other coastal environments (Elliott et al, 2007; Potter et al, 2015)
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