Contents lists available at ScienceDirect Ecological Indicators journal homepage: www.elsevier.com/locate/ecolind Multiple biogeochemical indicators of environmental quality in tropical estuaries reveal contrasting conservation opportunities Heliatrice Louise Hadlich a , Natalia Venturini b,1 , Cesar C. Martins c,1 , Vanessa Hatje d , Poliana Tinelli a , Luiz Eduardo de Oliveira Gomes a , Angelo Fraga Bernardino a, ⁎ a Grupo de Ecologia Bentônica, Departamento de Oceanografia e Ecologia, Universidade Federal do Espírito Santo, Avenida Fernado Ferrari, 514, Goiabeiras, Vitoria, ES, 29075-910, Brazil b Oceanografía y Ecología Marina, Instituto de Ecología y Ciencias Ambientales (IECA), Facultad de Ciencias, Universidad de la República (UdelaR), Iguá 4225, 11400 Montevideo, Uruguay c Centro de Estudos do Mar, Universidade Federal do Paraná, Caixa Postal 61, 83255-976 Pontal do Paraná, PR, Brazil d Centro Interdisciplinar de Energia e Ambiente (CIENAM), Instituto de Química, Universidade Federal da Bahia, Salvador, BA, Brazil ARTICLE INFO Keywords: Marine pollution Estuaries Organic biopolymers Sediments Trace metals Coprostanol ABSTRACT Estuaries are under major impacts from pollution even when managed as conservation units. Here we used multiple biogeochemical indexes of contamination and trophic status, including faecal sterols, biopolymers and trace metals, to determine and compare environmental quality of two tropical estuaries with contrasting con- servation status. In the metropolitan estuary, eutrophic/hypereutrophic conditions and high concentrations (> 1.0 μg g -1 ) of coprostanol were spatially correlated to sources of raw sewage input. Unexpected eutrophic sediments were also detected at the estuarine reserve, but with low sewage contamination indicating that high organic availability and burial predominated. The natural or polluted eutrophic sediments were determined by comparing multiple contamination indexes, which indicated sediment contamination within the metropolitan estuary. This study indicates that the long-term conservation of estuarine ecosystems on the Atlantic coast of Brazil are threatened by a typically poor sewage treatment and suggests that estuarine sediment quality need to be evaluated by multiple proxies before estuaries can be included in spatial conservation planning. 1. Introduction Estuaries worldwide have been heavily impacted by habitat trans- formation and pollution with severe risks to their ecological resilience (Lotze et al., 2006). The increasing pollution threaten the ecological services provided by estuaries, especially near urban centers where there is poor management of multiple impacts. In contrast to their low environmental quality, estuaries have become priority areas for con- servation and to be managed as marine reserves (Ducrotoy and Elliott, 2006; Gilby et al., 2017). Given that estuarine sediments may con- centrate pollutants (Dell’Anno et al., 2002; Baldock et al., 2004; Muniz et al., 2015), estuarine ecosystems need ecological indicators to ensure that protection is targeted to areas with higher environmental quality. The sedimentary organic matter (OM) and pollutants on estuaries are important drivers of ecological changes observed on benthic as- semblages and therefore biopolymers such as carbohydrates (CHO), lipids (LIP) and proteins (PRT), may be used as indicators for estuarine sediment quality (Nixon, 1995). The biopolymeric carbon (BPC) re- present the OM labile fraction that is readily available for benthic or- ganisms through remineralization (Aguiar et al., 2013), and therefore are highly sensitive to spatial and temporal changes in the benthic trophic status associated to both natural and human-induced environ- mental alterations (Dell’Anno et al., 2002; Pusceddu et al., 2003, 2009; Joseph et al., 2008). High concentrations of CHO with low nutritional value for benthic organisms may represent a degraded organic detritus (Joseph et al., 2008), whereas high PRT content, which is the main source of nitrogen for consumers, may reflect an increased fresh pro- ductivity (Danovaro et al., 1999). On the other hand, LIP have been used to indicate available energy to organisms and are indicators of detrital contributions derived from secondary production; furthermore, in polluted areas, LIP have been associated with anthropogenic sources of oil and sewage (Dell’Anno et al., 2002; Venturini et al., 2012). Therefore, the use of molecular markers in estuarine sediments are well established indicators of the benthic trophic status and identifying https://doi.org/10.1016/j.ecolind.2018.07.027 Received 7 May 2018; Received in revised form 12 July 2018; Accepted 13 July 2018 ⁎ Corresponding author. 1 These authors contributed equally to this work. E-mail address: angelo.bernardino@ufes.br (A.F. Bernardino). Ecological Indicators 95 (2018) 21–31 1470-160X/ © 2018 Elsevier Ltd. All rights reserved. T