Recovery Process on Soft-Bottom Macrobenthic Communities after Artificial Disturbance in Tropical Polluted Estuary (Guanabara Bay, Rio de Janeiro, Brazil)

Abstract

The regime of disturbance with natural or anthropogenic origin can lead to the destabilization or even to a mass mortality of benthic communities. Due to the heterogeneity of the disturbance there is a formation of patches in different stages of ecological succession. The aim of this study is to follow and describe the resilience in artificial disturbed sediment in a polluted bay in Rio de Janeiro. The sediment was collected, sterilized and placed inside corers (10 cm diameter × 15 cm height) in the same place where it was collected. We allocated the samples in two structures, the difference between them was that one was placed closed to the bottom and the other was placed 50 cm height. We found 2352 organisms distributed in 14 taxons. The class Polychaeta and the order Amphipoda showed the highest density in all the survey and treatments. We identified the factors influencing the scenarium: different mechanisms of dispersal, the posi-tion of the structures and life history of each group. Disturbance can be the main cause of the patch's diversity found in estuaries and coastal areas. Because of this, monitoring of selected areas becomes an important tool to understand the regime of disturbance as a key factor structuring benthic communities in soft sediment, also suggesting a metapopula-tion dynamics.

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).

“…The results suggests a species-specific dynamic seasonal colonization/defaunation pattern on a spatial gradient along the bay (Echeverría et al, 2010;Pereira et al, 2013). Species recolonize seasonally available areas from areas were favorable conditions are more stable along the year and retreats back in a seasonal climate-induced pattern (Day et al, 1989;Gray and Elliot, 2009).…”

“…In tropical estuaries, benthic biological processes are usually strongly influenced by the characteristics of the water mass above the communities, as well as the granulometric bottom structure (Day et al, 1989;Little, 2000;Gray and Elliot, 2009). Communities parameters reflect these conditions through variations in species composition and relative dominance, due to species-specific physiological tolerance to several factors, allied to particular dispersion pattern strategies (Day et al, 1989;Gray and Elliot, 2009;Echeverría et al, 2010;Neves et al, 2013;Pereira et al, 2013;Magalhães et al, 2014). The latter are modulated, in turn, by physical and chemical factors during adult's dispersion and settlement events (Alongi, 1989;Day et al, 1989;Valiela, 1995;Echeverría et al, 2010;Pereira et al, 2013).…”

“…may provide subsidies to evaluate assessment and monitoring environmental alterations related to sediments, such as dredging, sediment discharge and others. These environmental conditions exert an influence on benthic communities, by creating a mosaic with different dynamics, according to their relative position within the bay (Ghiselli Junior et al, 2003;Vilela et al, 2003;Ghiselli Junior, 2006;Echeverría et al, 2010;Pereira et al, 2013). The Cyprideis spp in the Guanabara Bay are abundants live in and above the sediments and possibly respond to seasonal variations (Sola and Paiva, 2001;Ghiselli Junior et al, 2003;Vilela et al, 2003;Ghiselli Junior, 2006).…”

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

“…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).…”

Spatiotemporal distribution of the benthic macrofauna in an urbanized subtropical estuary: environmental variations and anthropogenic impacts

“…% = accumulated percentual contribution for between group dissimilarity. in southeast Brazil also showed lower species richness at its inner and more polluted sectors (MENDES et al, 2006;TAVARES, 2009;PEREIRA et al, 2013) despite hosting around 300 species benthic macrofauna (SOARES-GOMES et al, 2016). Anthropic interventions and natural variability of the ecosystem end up favoring opportunistic and resilient species in the Itajaí-Açu river estuary, and the dominance of only a few species was also observed for the local carcinofauna (LEITE; PEZUTO, 2012).…”