Microbioerosão em conchas de Heleobia australis (Gastropoda: Rissooidea) da lagoa Salgada, Rio de Janeiro, Brasil

Abstract

Traces of microbioerosion are recorded on microgastropods shells that occur in association with recent stromatolites from lagoa Salgada, Rio de Janeiro State. The high destruction levels produced by microborers on the bioclasts were directly observed through optical and scanning electron microscroscopy. This study goals the identification and description of the bioerosion patterns on microgastropods of the species Heleobia australis (D'Orbigny). The microborings consist of sinuous ramified microborings galeries that were related to the ichnogenera Fascichnus, as well as groups of circular and irregular perforations that remained unidentified. Energy Dispersive X-Ray Spectrometry (EDS) analysis of the dark shells surfaces detected the elements sulfur and iron, both closely tied to the microbial metabolism.

Análise tafonômica e paleoecológica de estruturas associadas a comunidades microbianas holocênicas e permianas

“…The ostracods, in shades of grey, were found mainly as particles smaller than 0,5mm. Both ostracod and microgastropod shells showed signs of predation, as well as bioerosion, the latter as the result of cyanobacteria action, as reported by Senra et al (2006).…”

“…The microbialites and microbial mats of the Salgada Lagoon have been described by various authors Srivastava, 2002;Silva-e-Silva et al, 2005, 2007a, 2007b, 2008Silva-e-Silva and Senra, 2000;Senra et al, 2006;Iespa et al, 2011a). Similar structures are also found in other coastal lagoons of the state of Rio de Janeiro, such as those of the lagoons system of Araruama (Vermelha, Pitanguinha, and Pernambuco lagoons, Pau Fincado swamp, etc.…”

“…They were found in all of the sediments studied in whatever the granulometry. Although various authors, including Silva-e- Silva et al (2005aSilva et al ( , 2007a, Senra et al (2006) and Iespa et al (2011b), have reported the presence of numerous H. australis shells in the microbialites. The ostracods, in shades of grey, were found mainly as particles smaller than 0,5mm.…”

“…The literature review shows that most of the studies of microbialites and microbial mats in Rio de Janeiro state were designed to classify the cyanobacteria that form them (e.g., Silva-e-Silva et al, 2004, 2006b, 2007c, 2007dSilva-e-Silva and Senra, 2000;Silva-e-Silva and Carvalhal, 2005;. Studies of their diagenesis during the Holocene are less frequent Silva-e-Silva et al, 2007b;Senra et al, 2006;Iespa et al, 2011b;McKenzie and Vasconcelos, 2009;Spadofora et al, 2010).…”

A utilização de biominerais como possíveis bioassinaturas microbianas

“…In Brazil, they have been reported in hypersaline lagoons in Rio de Janeiro State, such as the Lagoa Vermelha (e.g., Vasconcelos et al 2006;Spadofora et al 2010;Delfino et al 2012) and the Lagoa Salgada (Rodrigues et al 1981;Srivastava 2002;Senra et al 2006;Iespa et al 2011;Silva e Silva et al 2013;and Birgel et al 2015). In Lagoa Salgada, domal-shaped stromatolites (with thrombolitic mesostructure) and well-developed microbial mats are found forming different biofacies.…”