ISSN:
1573-5125
Keywords:
Sediment toxicity
;
bioluminescent bacteria
;
sediment contamination
;
macrofaunal communities
;
Sado estuary
;
Portugal
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract This paper presents the results from a sedimentary survey undertaken in July 1992 in the Sado estuary, western coast of Portugal. Sediment samples were taken at 14 sites, corresponding to four organic enrichment gradients, three of which are located close to harbour facilities or to industrial or urban effluent outfalls. The fourth site is located away from direct sources of anthropogenic disturbance. An integrated approach was conducted in order to study the quality status of the superficial sediments, and included 1. the analysis of sediment descriptors and contaminants (grain-size, total organic matter, heavy metals, PCBs), 2. the evaluation of toxicity, using bioluminescent bacteria and the Microtox® solid-phase protocol and 3. the study of macrofaunal communities structure and composition. Most of the sediments showed low IC50 values (high toxicity), while benthic macrofauna did not indicate community disturbance in most of the sites, nor the contaminants analysed provided explanation for the potential toxicity observed. Most of the sediments showed high fines content. A statistical significant relation between fines and IC50 values was found, indicating the sensitivity of the toxicity assessment method for granulometry. This sensitivity might explain the lack of agreement between the IC 50 values and the sediment chemistry-infaunal communities structure. The potential grain-size sensitivity was further analysed using another test sediment from which artificial samples with different sand∶fines ratios were prepared. It is concluded that extreme caution should be used when applying the solid-phase Microtox® protocol to assess the toxicity of natural sediments, covering a range of granulometry and contamination situations.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02084241
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