Costa Filipe O, Neuparth Teresa, Correia Ana D, Costa Maria Helena
IMAR - Centro de Modelação Ecológica, DCEA, F.C.T., Univ. Nova de Lisboa, 2829-516 Caparica, Portugal.
Mar Environ Res. 2005 Jul;60(1):93-110. doi: 10.1016/j.marenvres.2004.08.005.
This study aimed to test the performance of the amphipod Gammarus locusta (L.) in chronic sediment toxicity tests. It constitutes part of a multi-level assessment of chronic toxicity of estuarine sediments, integrating organism and population-level endpoints with biochemical markers responses. Here we account for organism and population-level effects, while biomarker responses were reported in a companion article. Five moderately contaminated sediments from Sado and Tagus estuaries were tested, comprising 3 muddy and 2 sandy sediments. These sediments either did not show acute toxicity or were diluted with control sediment as much as required to remove acute toxicity. Subsequent chronic tests consisted of 28-day exposures with survival, individual growth and reproductive traits as endpoints. Two of the muddy sediments induced higher growth rates in the amphipods, and improved reproductive traits. This was understood to be a consequence of the amount of organic matter in the sediment, which was nutritionally beneficial to the amphipods, while concurrently decreasing contaminant bioavailability. Biomarker responses did not reveal toxicant-induced stress in amphipods exposed to these sediments. One of the sandy sediments was acutely toxic at 50% dilution, but in contrast stimulated amphipod growth when diluted 75%. This was presumed to be an indication of a hormetic response. Finally the two remaining contaminated sediments showed pronounced chronic toxicity, affecting survival and reproduction. The sex ratio of survivors was highly biased towards females, and offspring production was severely impaired. The particulars of the responses of this amphipod were examined, as well as strengths versus limitations of the sediment test. This study illustrates the utility of this chronic test for toxicity assessment of contaminated estuarine sediments, with potential application all along Atlantic Europe.
本研究旨在测试河虾（Gammarus locusta (L.)）在慢性沉积物毒性试验中的表现。它是河口沉积物慢性毒性多层次评估的一部分，将生物个体和种群水平的终点指标与生化标志物反应相结合。在此我们阐述生物个体和种群水平的影响，而生物标志物反应在一篇配套文章中报告。测试了来自萨多河和塔霍河河口的五种中度污染沉积物，包括3种泥质沉积物和2种砂质沉积物。这些沉积物要么未表现出急性毒性，要么用对照沉积物按要求进行稀释以消除急性毒性。随后的慢性试验包括为期28天的暴露，以生存、个体生长和繁殖特征作为终点指标。其中两种泥质沉积物使河虾的生长速率更高，并改善了繁殖特征。据认为，这是沉积物中有机物含量的结果，这些有机物对河虾在营养方面有益，同时降低了污染物的生物可利用性。生物标志物反应未揭示暴露于这些沉积物的河虾受到毒物诱导的应激。其中一种砂质沉积物在稀释50%时具有急性毒性，但相反，在稀释75%时刺激了河虾生长。这被推测是一种 hormetic 反应的迹象。最后，其余两种受污染沉积物表现出明显的慢性毒性，影响生存和繁殖。幸存者的性别比例严重偏向雌性，后代产量严重受损。研究了这种河虾反应的具体情况以及沉积物试验的优点与局限性。本研究说明了这种慢性试验在受污染河口沉积物毒性评估中的实用性，在整个欧洲大西洋沿岸都有潜在应用。
