Intra-annual variation in rainfall and it’s influence of the adult’s Cyprideis spp (Ostracoda, Crustacea) on a eutrophic estuary (Guanabara Bay, Rio de Janeiro, Brazil).

Abstract

<jats:p>Abstract Spatial and temporal distribution of two species of adult´s ostracods (Cyprideis sp. and Cyprideis salebrosa) were studied as a function of the rainfall patterns in the Guanabara Bay, Rio de Janeiro, Brazil. Samples were taken in ten stations, along six surveys representing three periods (Dry, Early and Late Rainy) for two years. Stations were nested in four areas (Outer, Central, EPA Guapimirim and Impacted). The bottom water (temperature, salinity, dissolved oxygen and oxygen saturation) were measured in each area to characterize the influence of seasonal variations by rainfall. Cyprideis sp. and Cyprideis salebrosa showed patterns distribution to seasonality/surveys (p = 0,002 and p &lt;0,001, respectly). The spatial distribution of Cyprideis sp was significantly different areas studied (p &lt;0.001) indicated well defined areas and distribution in along of the surveys. However, C. salebrosa showed homogeneous distribution in along of the areas within of each survey (p &lt;0.001). Redundancy Analysis (RDA) for the two years evidenced environment preference of the Cyprideis sp. for areas with marine conditions (high influence for channel central) and C. salebrosa for brackish water (high influence of the rivers). This observation reinforces of the existence of areas created by the seasonality of pluviometric regime, a possible dispersion of the adult’s ostracods and possibility the use with bioindicators.</jats:p>

Spatio-temporal sublittoral macrobenthic distribution and dominant species in Guanabara Bay, Rio de Janeiro, Brazil

“…The results evidence a distinct spatial distribution among the sectors with differences in the composition of the assemblages because of the heterogeneity of abiotic conditions (sediment, bottom water, continental input and others). The sectorization observed in the results is widely discussed in other works due to its oceanographic and biological characteristics (Echeverría et al, 2010;Neves et al, 2013;Pereira et al, 2013;Francisco and Netto, 2020;Pessoa et al, 2020). Our results provide a sectorization based not only on abiotic characteristics, but also on the distribution of fauna by their possible indicators.…”

“…Most of species had low frequency and abundance. This pattern of few dominant species is found in highly impacted environments, reflecting the high dominance of opportunistic species (Echeverría et al, 2010;Neves et al, 2013;Pereira et al, 2013;Pessoa et al, 2020).…”

“…In addition to environmental conditions, community dynamics, and biological pressures exerted by species from other ecological compartments, specific strategies, such as dispersion, tube formation, intra and interspecific relations can also contribute to characterize these communities (Gray and Elliott, 2009;Echeverría et al, 2010;Neves et al, 2013;Pereira et al, 2013;Negrello-Filho et al, 2018;Pessoa et al, 2020).…”