Department of Biology & CESAM, University of Aveiro, Campus Universitário de Santiago, Aveiro, Portugal.
Department of Biology, University of Naples Federico II, via Cinthia ed. 7, 80126, Naples, Italy.
Mar Environ Res. 2018 Sep;140:135-144. doi: 10.1016/j.marenvres.2018.06.003. Epub 2018 Jun 7.
Oysters are a diverse group of marine bivalves that inhabit coastal systems of the world's oceans, providing a variety of ecosystem services, and represent a major socioeconomic resource. However, oyster reefs have become inevitably impacted from habitat destruction, overfishing, pollution and disease outbreaks that have pushed these structures to the break of extinction. In addition, the increased frequency of climate change related events promise to further challenge oyster species survival worldwide. Oysters' early embryonic development is likely the most vulnerable stage to climate change related stressors (e.g. salinity and temperature shifts) as well as to pollutants (e.g. arsenic), and therefore can represent the most important bottleneck that define populations' survival in a changing environment. In light of this, the present study aimed to assess two important oyster species, Crassostrea angulata and Crassostrea gigas embryo-larval development, under combinations of salinity (20, 26 and 33), temperature (20, 24 and 28 °C) and arsenic (As) exposure (0, 30, 60, 120, 240, 480, 960 and 1920 μg. As L), to infer on different oyster species capacity to cope with these environmental stressors under the eminent threat of climate change and increase of pollution worldwide. Results showed differences in each species range of salinity and temperature for successful embryonic development. For C angulata, embryo-larval development was successful at a narrower range of both salinity and temperature, compared to C. gigas. Overall, As induced higher toxicity to C. angulata embryos, with calculated EC50 values at least an order of magnitude lower than those calculated for C. gigas. The toxicity of As (measured as median effective concentration, EC50) showed to be influenced by both salinity and temperature in both species. Nonetheless, salinity had a greater influence on embryos' sensitivity to As. This pattern was mostly noticed for C. gigas, with lower salinity inducing higher sensitivity to As. Results were discussed considering the existing literature and suggest that C. angulata populations are likely to become more vulnerable under near future predictions for temperature rise, salinity shifts and pollution.
牡蛎是一类生活在世界海洋沿岸系统中的海洋双壳类动物，它们提供了多种生态系统服务，是一种重要的社会经济资源。然而，由于栖息地破坏、过度捕捞、污染和疾病爆发等原因，牡蛎礁不可避免地受到了影响，这些结构已经濒临灭绝。此外，与气候变化相关的事件的发生频率增加，这将进一步挑战全球牡蛎物种的生存。牡蛎的早期胚胎发育阶段可能是最容易受到与气候变化相关的压力因素（如盐度和温度变化）以及污染物（如砷）影响的脆弱阶段，因此，它可能是定义种群在变化环境中生存的最重要瓶颈。有鉴于此，本研究旨在评估两种重要的牡蛎物种——亚洲真牡蛎（Crassostrea angulata）和长牡蛎（Crassostrea gigas）的胚胎-幼虫发育情况，研究采用盐度（20、26 和 33）、温度（20、24 和 28°C）和砷（As）暴露（0、30、60、120、240、480、960 和 1920μg As L）的组合，以推断不同牡蛎物种在面临气候变化的严峻威胁和全球污染增加的情况下应对这些环境压力的能力。结果表明，两种物种的胚胎发育成功范围在盐度和温度上存在差异。对于 C. angulata 来说，与 C. gigas 相比，其胚胎-幼虫发育在盐度和温度的范围更窄。总的来说，As 对 C. angulata 胚胎的毒性更高，其计算得出的 EC50 值至少低一个数量级。As 的毒性（以半数有效浓度，EC50 来衡量）在两种物种中均受到盐度和温度的影响。尽管如此，盐度对胚胎对 As 的敏感性影响更大。这种模式在 C. gigas 中最为明显，低盐度会导致对 As 的敏感性更高。研究结果在考虑现有文献的基础上进行了讨论，结果表明，在未来对温度升高、盐度变化和污染的预测下，C. angulata 种群可能会变得更加脆弱。
