Assessing mercury contamination in a tropical coastal system using the mussel Perna perna and the sea anemone Bunodosoma caissarum Nafisa Rizzini Ansari & Marcos Antônio Fernandez & José Lailson Brito Jr. & Lara Gama Vidal & Erika Silva de Andrade Costa & Olaf Malm Received: 23 February 2016 /Accepted: 7 November 2016 # Springer International Publishing Switzerland 2016 Abstract Total mercury concentrations in the mussel Perna perna and the sea anemone Bunodosoma caissarum were determined to assess Hg contamination in Guanabara Bay, Rio de Janeiro, Brazil, and an adja- cent sea area. Concentrations in the tissues of these species were compared. Average total mercury concen- trations ranged from 3.54 to 21.01 μg kg -1 (wet wt.) in P. perna and from 4.51 to 23.19 μg kg -1 (wet wt.) for B. caissarum. Concentrations varied according to the sampling stations. Distribution of concentrations for both species was similar along the sampling stations, and a significant correlation was observed. Results sug- gest that B. caissarum could be a suitable biomonitor species for mercury contamination in the study area and could be used as a complementary species for monitor- ing studies. Further research is, however, needed to assess how environmental conditions and other vari- ables affect Hg concentrations in B. caissarum. Keywords Contamination . Mercury . Biomonitoring . Guanabara Bay . Cagarras Archipelago Introduction Estuaries are subject to substantial physical, chemical, and biological stresses due to their sheltering properties for human developments (Wagener et al. 2012). Guanabara Bay is a eutrophic estuary located in the metropolitan area of Rio de Janeiro in Brazil. This bay has important fisheries. It also has intense commercial and leisure navigation. The commercial uses include transportation, shipyards, oil terminals, and refineries. This activity is supported by two ports, Rio de Janeiro and Niterói. In addition, the hydrographic basin of the bay constitutes the second major industrial complex in Brazil and is densely populated (Covelli et al. 2012; Kehrig et al. 2009; Kjerfve et al. 1997; Wagener et al. 2012). The bay’ s hydrographic basin has a long history of heavy industry and growing urbanization, so high levels of multiple contaminants, such as heavy metals and organic compounds, are discharged into the bay waters (Baptista Neto et al. 2005; Baptista Neto et al. 2006; Carreira et al. 2004; Fernandez et al. 2005; Fonseca et al. 2009; Kehrig et al. 2009; Wagener et al. 2012). This eutrophic bay still receives large loads of untreated indus- trial and domestic sewage from its drainage basin. Low concentrations of mercury (Hg) are naturally found in aquatic ecosystems, and anthropogenic activi- ties have increased Hg levels over the last century (Mason et al. 2012). Hg is a heavy metal that can be toxic even in very low concentrations depending on the chemical species present in the environment (Ullrich et al. 2001). For example, depending on the environ- mental conditions, inorganic Hg can be converted to Environ Monit Assess (2016) 188:679 DOI 10.1007/s10661-016-5683-7 N. Rizzini Ansari (*) : M. A. Fernandez : J. L. Brito Jr., : L. G. Vidal : E. S. de Andrade Costa Faculdade de Oceanografia, Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier, 524/401 8E, 20550-013, Maracanã, Rio de Janeiro, Brazil e-mail: nafisarizzini@yahoo.com O. Malm Instituto de Biofísica, Universidade Federal do Rio de Janeiro, Bloco G/CCS, 21941-902, Ilha do Fundão, Rio de Janeiro, Brazil