Seasonal effects on hyporheic meiofauna structuring in sites with low and high urbanization in a South American tropical river

Studies on meiofauna diversity and taxonomy are fundamental for a better understanding of their community structure. Hyporheic meiofauna has not been studied, as well as the beach, marine, and estuarine meiofauna. The present work aimed to characterize the Beberibe River meiofauna community at two points: one with high urbanization (HU) and the other with low urbanization (LU), both located in the metropolitan region of Recife, Pernambuco, Brazil. Meiofaunistic responses to urbanization and seasonal effects were studied in terms of distribution, abundance, richness, and diversity. These benthic organisms were collected in two different seasons (dry and wet seasons) at depths of 0 to 5 cm and 5 to 10 cm, at two different sampling points in a hyporheic environment. At the LU point, there is a remnant from the Atlantic Forest. The HU point is in a very urbanized area, suffering considerable domestic discharge of organic and solid waste. Granulometric characterization, pH, temperature, and salinity were estimated in each sample point and season. The Hill numbers integrated indices were used to quantify and ascertain taxonomic diversity. Nonparametric analyses were also carried out through Similarity Analysis (ANOSIM), Principal Component Analysis (PCA), and Permutational Analysis (PERMANOVA). The confidence interval adopted was 95%. 269 meiofauna individuals were found, with the highest abundance distributed in the wet season. There were significant differences in the distributions of the organisms at both points (p < 0.05) and between two sampling seasons (p < 0.05). No significant difference was found for the depth stratification (p > 0.05).