Syllidae (annelida: polychaeta) como indicador de qualidade ambiental em uma região de plataforma continental tropical sob influência de uma piscicultura marinha experimental

Abstract

This study examines the influence of organic enrichment from cobia (Rachycentron canadum, Linnaeus 1766) fish farming under the Syllidae community (Annelida: Polychaeta) structure in the shallow continental shelf of the State of Pernambuco, northeastern Brazil. Thus, a perpendicular transect to the shore line was performed from east to the west of the floating cages. the stations were placed at 0 m, beneath the cages, 30 and 100 m away. Additionally a displaced transect station 200 m distance was also sampled. Biological samples were taken in three replicates per station in three times - initial, intermediate and final. Environmental parameters were measured as temperature (°C), salinity, dissolved oxygen concentration (mg.L-¹), pH and concentration of chlorophyll-a (µg.L-¹), total nitrogen (mg.L-¹) and the percentage of organic carbon in one replicate per station. The results were analyzed using univariate and multivariate techniques such as an ANOVA and PCA for the environmental parameters and Syllidae community was evaluated by K-dominance curves, PERMANOVA together with a NMDS and a analysis of similarity percentage, SIMPER. The two axes of the PCA to the measured environmental parameters summarized 76.65% of total variance. Can be verified that the moments distinguish themselves. The influence of marine fish farming on the structure of Syllidae community was evident only among the moments where all species found behaved as tolerant / opportunists, increasing its density as the organic material input. Some species of the subfamily Exogoninae as Sphaerosyllis sp1 and Exogone gigas Paresque, Fukuda & Nogueira, 2014 were the main responsible, for the perceived changes. With the design was not possible to verify the existence of a gradient of distance in the changes produced by fish farming, however the station 0 m, just below the culture, the diversity increases at an intermediate time and then falls at the final. Additionally a new species of the genus Syllidae Syllis found and is described in this paper.