Atenção: Esse site só pode ser visualizado perfeitamente em um browser que suporta Web Standards. É recomendável que você atualize o seu browser clicando aqui. Obrigado e desculpe o transtorno.


Use of ecotoxicological tests to support the environmental quality assessments of marine sediments

Long-term studies of ecosystems have been used in several branches of ecology (Jassby and Powell, 1990) and have provided valuable information on the natural fluctuation of species and communities (Clark, 2001). Environmental monitoring studies are currently used as one of the main sources of historical data on biotic communities; however, such data are not often analyzed in an integrated manner and studies of this dimension tend to be considered a large collection of data.

In order to consider the possibility of optimizing these monitoring procedures, this study was intended to analyze the relation between the zoobenthic community of non-consolidated substrate from coastline and the result of chronic ecotoxicological tests using benthic copepod Nitokrasp.

This study was performed in the coastal region of the internal continental platform adjacent to Praia Mole, State of Espírito Santo, and is part of results of marine monitoring on this region. It was used to assess possible environmental impacts by a company in the steel industry. The relation between the egg hatch rate from the chronic ecotoxicological tests in sediments, the density of benthic organisms and abiotic factors (dissolved oxygen, hydrogenionic potential (pH) and salinity) was analyzed during the Autumn and Spring of 2013. A variance analysis was employed to detect the existence of significant differences between data and to this end the benthic community?s density values were logarithmized to the 10th power. After analyzing the results that presented a significant difference, they were reassessed using the T-Test. Furthermore, a canonical correspondence analysis was held to assess the relation between the physical and chemical factors and organism density.

The results showed that there were no significant difference (p>0.05) between benthos density in the samples and copepod density in the chronic ecotoxicological results when compared among the sampling stations; therefore, a similar fluctuation between the density of benthic organisms and of copepods was observed. Yet, there was a significant difference (p<0.05) between zoobenthic density when related to the seasonal period, which was not observed with regard to copepod density in the ecotoxicological results. It was also observed that for abiotic factors, the canonical correspondence analysis evidenced that the distribution of benthic organisms and copepods was related to the amount of oxygen dissolved in the in situ samples.

Based on this result, a possible relation was observed between fluctuation of the zoobenthic community in monitoring stations and reproduction of the copepod Nitokra sp. in laboratory, which indicates the substitution potential of the quantitative analyses of zoobenthos by ecotoxicological tests used to assess the environmental quality of marine sediments. However, benthic community analyses are essential for monitoring and, thus, this type of assessment can be used to develop a pre-analysis of the area to be monitored and to identify the most sensitive or impacted locations in the coastal environment, serving as guidance to define the main locations to be monitored. In conclusion, analyses are recommended over a longer period of time to assess possible fluctuations of zoobenthic communities and to identify environmental specifics.