Università Politecnica Delle Marche, Dipartimento di Scienze Della Vita e Dell'Ambiente, 60131, Ancona, Italy.
University of Barcelona, CRG Marine Geosciences, Department of Earth and Ocean Dynamics, 08028, Barcelona, Spain.
Environ Pollut. 2022 May 15;301:119021. doi: 10.1016/j.envpol.2022.119021. Epub 2022 Feb 19.
Industrial seabed mining is expected to cause significant impacts on marine ecosystems, including physical disturbance and the generation of plumes of toxin-laden water. Portmán Bay (NW Mediterranean Sea), where an estimated amount of 60 Mt of mine tailings from sulphide ores were dumped from 1957 to 1990, is one of the most metal-polluted marine areas in Europe and worldwide. This bay can be used to assess the impact on marine ecosystems of particle settling from sediment plumes resulting from mine tailings resuspension. With this purpose in mind, we conducted a field experiment there to investigate subsequent effects of deposition of (artificially resuspended) contaminated sediments on (i) prokaryotic abundance and meiofaunal assemblages (in terms of abundance and diversity), (ii) the availability of trophic resources (in terms of organic matter biochemical composition), and (iii) a set of ecosystem functions including meiofaunal biomass, heterotrophic C production and C degradation rates. The results of this study show that mine tailings resuspension and plume deposition led to the decline of prokaryotic abundance and nematode's biodiversity. The later decreased because of species removal and transfer along with particle resuspension and plume deposition. Such changes were also associated to a decrease of the proteins content in the sediment organic matter, faster C degradation rates and higher prokaryotic C production. Overall, this study highlights that mine tailing resuspension and ensuing particle deposition can have deleterious effects on both prokaryotes and nematode diversity, alter biogeochemical cycles and accelerate C degradation rates. These results should be considered for the assessment of the potential effects of seabed mineral exploitation on marine ecosystems at large.
工业海底采矿预计将对海洋生态系统造成重大影响，包括物理干扰和含有毒素的水羽流的产生。波尔特曼湾（西北地中海）是欧洲乃至全球金属污染最严重的海洋区域之一，1957 年至 1990 年间，估计有 6000 万吨硫化物矿石的尾矿倾倒在这里。该湾可用于评估海底采矿尾矿再悬浮导致的沉积物羽流中颗粒沉降对海洋生态系统的影响。基于此目的，我们在那里进行了一项现场实验，以研究（人工再悬浮的）污染沉积物沉积对以下方面的后续影响：(i) 浮游生物丰度和小型底栖生物群落（丰度和多样性），(ii) 营养资源的可用性（以有机物生化组成的形式），以及 (iii) 包括小型底栖生物生物量、异养 C 生产和 C 降解率在内的一系列生态系统功能。本研究结果表明，尾矿再悬浮和羽流沉积导致浮游生物丰度和线虫生物多样性下降。后者的减少是由于物种的去除和转移以及颗粒的再悬浮和羽流沉积。这种变化还与沉积物有机质中蛋白质含量的减少、更快的 C 降解率和更高的原核生物 C 生产有关。总体而言，本研究强调了尾矿再悬浮和随之而来的颗粒沉积可能对原核生物和线虫多样性产生有害影响，改变生物地球化学循环并加速 C 降解率。这些结果应在评估海底矿产开采对海洋生态系统的潜在影响时加以考虑。
