Benthic foraminifera distribution in a tourist lagoon in Rio de Janeiro, Brazil: A response to anthropogenic impacts Claudia Gutterres Vilela a,⇑ , Daniele Silva Batista a , José Antonio Baptista Neto b , Renato Olindo Ghiselli Jr. c a Depto de Geologia, IGEO, CCMN/Universidade Federal do Rio de Janeiro, Av. Athos da Silveira Ramos 274, Cidade Universitária, 21941-916 Rio de Janeiro, RJ, Brazil b Instituto de Geociências, Lagemar/Universidade Federal Fluminense, Av. Litorânea s/n, Gragoatá, 24210-340 Niterói, RJ, Brazil c Instituto Oceanográfico, Universidade de São Paulo, Praça do Oceanográfico 191, Cidade Universitária, 05508-900 São Paulo, SP, Brazil article info Keywords: Foraminifera Ostracodes Heavy metals Organic matter Pollution bioindicator Brazilian southeastern lagoon abstract Rodrigo de Freitas Lagoon, located in the Rio de Janeiro City, receives several types of polluted discharges. The knowledge of the sediment microfauna correlated with heavy metal and organic matter concentra- tions could supply important data about the conditions of the lagoon. The benthic foraminiferal assem- blage presented larger diversity and more abundant samples in the lagoon entrance than in the inner area. The Ammonia tepida – Elphidium excavatum foraminiferal assemblage is characterized by dwarf, cor- roded and weak organisms. Agglutinated species were found only near the entrance. Low abundance val- ues and sterility of five samples in the inner area (north/northeast) can be caused by high levels of heavy metals and organic matter. A. tepida shows negative correlation with increasing heavy metals values. PAHs and coprostanol high indexes, and the absence or low presence of microfauna in samples around the lagoon margin confirm illegal flows from gas stations and domestic sewage. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction The aim of this study is to understand the present environmen- tal conditions of the Rodrigo de Freitas Lagoon, southeast Brazil, by obtained detailed knowledge of the benthic foraminifera in bottom sediments, including the characterization of foraminiferal assem- blages, with their pattern of abundance, dominance and diversity. We compared the data on foraminifera with data on ostracode occurrences, in some samples. The microfaunal data was evaluated with results of the concentration of heavy metals in the sediment samples, sediment characteristics including grain size, and content of organic matter. The occurrence of foraminiferal microfauna in the lagoon was first related by Brito and Lemos (1982), which ana- lysed samples derived from dredging in the east of the Rodrigo de Freitas Lagoon, close to Catacumba Park, highlighting only the presence of few calcareous genera. Benthic foraminifera are commonly used as bioindicators in ecological studies, including the determination of human impacts in coastal and paralic environments (Alve, 1991, 1995; Boltovskoy et al., 1991; Murray, 1991; Sharifi et al., 1991; Culver and Buzas, 1995; Yanko et al., 1998; Alve and Olsgard, 1999; Debenay et al., 2000, 2001; Geslin et al., 2002; Vilela et al., 2004, 2007). Knowl- edge of microfaunal assemblages and their response to changes in the environment contribute to evaluation of the sediments from coastal environments heavily impacted by human populations. Foraminifera can be excellent environmental bioindicator species (e.g. Alve, 1995), and studies of their fossil occurrences help in evaluating environmental degradation taking place before the environments were monitored, especially because foraminifera are commonly the last eukaryote organisms to disappear in strongly polluted environments (Schafer et al., 1975; Scott et al., 1995a, 2001). They are able to proliferate in regions that are not efficiently colonized by other organisms (Schafer, 1973) and their assemblages consist of low diversity, high dominance and opportu- nistic species (e.g. Schafer et al., 1975; Alve, 1995). Many papers document the common to abundant occurrence of deformed foraminiferal tests where sediments are contaminated by organic matter (including hydrocarbons) and or trace metals (Naidu et al., 1985; Sharifi et al., 1991; Yanko et al., 1994, 1998; Schafer, 2000; Le Cadre and Debenay, 2006; Geslin et al., 2002). Metal pollution is common in coastal environments, and has been much investigated because metals are toxic to many metazo- ans (Donazzolo et al., 1981) and can affect primary productivity (Vazquez et al., 1999). The space variation of heavy metal concen- tration levels in surficial sediments of the urbanized coastal envi- ronments is attributed to the sources of pollution of different origins (Förstner, 1989). Suspension material in rivers acts as 0025-326X/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.marpolbul.2011.07.023 ⇑ Corresponding author. Address: Rua Athos da Silveira Ramos 274, Depto. de Geologia, UFRJ, Cidade Universitária, 21941-916 Rio de Janeiro, RJ, Brazil. Tel.: +55 21 2598 9484; fax: +55 21 2598 9465. E-mail addresses: claudiagvilela@ufrj.br, claudiagvilela@gmail.com, vilela@ geologia.ufrj.br (C.G. Vilela), jneto@igeo.uff.br (J.A. Baptista Neto), olinghijr@ ig.com.br (R.O. Ghiselli). Marine Pollution Bulletin 62 (2011) 2055–2074 Contents lists available at SciVerse ScienceDirect Marine Pollution Bulletin journal homepage: www.elsevier.com/locate/marpolbul