Assessing the ecological effects of contaminants in estuaries in Brazil: Gaps and future directions

Abstract

This chapter reviews published papers from the last 15 years that estimate the effects of contamination in Brazilian estuaries. The goals were to identify (i) the main classes of contaminants studied in estuarine systems in Brazil; (ii) the most used lines of evidence (LOEs) to estimate the effects of contaminants; (iii) the most common experimental designs and statistical analysis; and (iv) the major gaps in the field and suggest future directions. A total of 130 papers were reviewed. Metals were the most measured contaminant (34.6%) followed by organic contaminants (13.1%). Most papers (56.9%) only used one line of evidence (LOE) and the most common LOE were bioaccumulation (40.8%) followed by media chemistry (39.2%) and biomarkers analysis (33.8%). Most papers (59.6%) did not report the salinity range of the studied system, had three or less spatial replicates (56.4%), and did not include temporal replication (48.1%) or reference sites (52.6%) in their design. The most used analyses were ANOVA (44.6%) and correlation (26%). Some suggestions for future studies are: (i) consider the salinity range of the studied sites when planning the experimental designs; (ii) include appropriate reference areas; (iii) clearly state the question and the null hypothesis to be tested, (iv) evaluate the possible effect of covariates when performing bioaccumulation and biomarker studies; and (v) include more than one LOE in the design if possible. Enhancing the collaboration among scientists in different states and regions of Brazil may reduce the gap in our knowledge of the effects of contaminants in many estuaries.