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Integration of varying responses of different organisms to
water and sediment quality at sites impacted and not impacted
by the petroleum industry
A. Nascimento, , D.H. Smith, S.A. Pereira,
M.M. Sampaio de Araújo, M.A. Silva,
A.M. Mariani
Institute of Biology, Federal
University of Bahia, Campus Universitario of Ondina., 40170-210,
Salvador, Bahia, Brazil
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Abstract
The toxicity of surface waters and interstitial waters
from sediments were determined at six study sites in Todos os Santos
Bay, Bahia, Brazil, to evaluate the possibility of chronic environmental
impact induced by 40 years of exposure to the local petroleum industry.
Samples collected from four sites associated with the extraction,
transportation and refinement of petroleum, and from two control
sites, were tested at seven thee-month intervals. Toxicological
assays using acute mortality of brine shrimp (Artemia saline)
nauplii and chronic abnormalities of sea urchin (Echinometra
lucunter) and mangrove oyster (Crassostrea rhizophorae)
larvae were employed. Friedman non-parametric analyses of variance
integrated seasonal variations in species response patterns and
revealed significant differences among the study sites. Ranging
the among-site variations for each organism in each sampling period,
on a scale from 0.00 (minimum response) to 1.00 (maximum response),
permitted the calculation of a single mean value for each species
and the ordination of the sites on a qualitative scale of relative
impact. Although the ordinations varied with species, the reduction
of three species response patterns to a common relative scale also
permitted their integration into a single multispecies ordination
of the study sites. A cluster analysis of the six sites and two
aquatic substrates, based on their toxicity to all three species,
illustrated the similarities and differences between locations.
Interstitial waters were more toxic, revealing an integrated ordination
of Station 6 < Station 5 < (Station 3 = Station2) < (Station
4 = Station 1). The ordination based on surface waters was Station
6 < Station 5 < (Station 2 = Station = Station 3) < Station
4. In combination, the three procedures served efficiently for the
description and inferential testing of the multispecies responses
and, complemented with additional data on species diversity and
chemical contamination of the sediment, confirmed the existence
of chronic impact within the study area. © 2000 Elsevier Science
Ltd and AEHMS. All rights reserved.
Keywords: Chronic toxicity; Multispecies response; Integration
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