Moreira Anthony, Figueira Etelvina, Pecora Iracy L, Soares Amadeu M V M, Freitas Rosa
Departmento de Biologia & CESAM, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
Departmento de Biologia & CESAM, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
Comp Biochem Physiol C Toxicol Pharmacol. 2017 Jan;191:183-193. doi: 10.1016/j.cbpc.2016.10.008. Epub 2016 Nov 3.
The increase of temperature in marine coastal ecosystems due to atmospheric greenhouse gas emissions is becoming an increasing threat for biodiversity worldwide, and may affect organisms' biochemical performance, often resulting in biogeographical shifts of species distribution. At the same time, the introduction of non-native species into aquatic systems also threatens biodiversity and ecosystem functions. Oysters are among the most valuable socio economic group of bivalve species in global fishery landings, and also provide numerous ecosystem services. However, the introduction of non-native oyster species, namely Crassostrea gigas for aquaculture purposes may threaten native oyster species, mainly by out competing their native congeners. It is therefore of upmost importance to understand physiological and biochemical responses of native and introduced oyster species in a scenario of global temperature rise, in order to provide knowledge that may allow for better species management. Hence, we compared biochemical alterations of the introduced C. gigas and the native Crassostrea brasiliana, the most important oyster species in Brazil, in response to different thermal regimes for 28days (24, 28 and 32°C). For this, metabolism (ETS), energy content (GLY), antioxidant system (SOD, CAT and GSH/GSSG) and cellular damage (LPO) were assessed in adult and juvenile specimens of both species. Juvenile C. gigas were the most affected by increased temperatures, presenting higher mortality, more pronounced antioxidant response (SOD), whereas adults were more tolerant than juveniles, showing no mortality, no significant changes in antioxidant enzymes activity neither energy expenditure. Native C. brasiliana juveniles presented lower mortality and less pronounced biochemical alterations were noted at higher temperature comparing to non-native C. gigas juveniles. Adult C. brasiliana were the least responsive to tested temperatures. Results obtained in this study bring interesting new insights on different oyster species life stages' physiological and biochemical tolerance towards thermal stress. The native species C. brasiliana showed ability to maintain biochemical performance at higher temperatures, with less pronounced biochemical changes than the non-native species. The introduced (C. gigas) showed to be more sensitive, presenting biochemical alterations to cope with the increase of temperature. Despite the lower observed fitness of the introduced species to temperatures closer to those naturally experienced by the native species, the ability of C. gigas to cope with higher temperatures should still raise concerns towards the native species C. brasiliana management and protection.
由于大气温室气体排放导致的海洋沿岸生态系统温度升高，正日益威胁着全球生物多样性，并可能影响生物体的生化性能，常常导致物种分布的生物地理转移。与此同时，将非本地物种引入水生系统也威胁着生物多样性和生态系统功能。牡蛎是全球渔业上岸量中最具价值的双壳类物种社会经济群体之一，还提供众多生态系统服务。然而，为水产养殖目的引入非本地牡蛎物种，即太平洋牡蛎，可能会威胁本地牡蛎物种，主要是通过与其本地同属物种竞争。因此，了解本地和引入的牡蛎物种在全球气温上升情况下的生理和生化反应至关重要，以便提供有助于更好地进行物种管理的知识。因此，我们比较了引入的太平洋牡蛎和巴西最重要的牡蛎物种本地巴西牡蛎在不同热状态下28天（24、28和32°C）的生化变化。为此，评估了这两个物种的成体和幼体标本的代谢（ETS）、能量含量（GLY）、抗氧化系统（SOD、CAT和GSH/GSSG）以及细胞损伤（LPO）。幼体太平洋牡蛎受温度升高影响最大，死亡率更高，抗氧化反应（SOD）更明显，而成体比幼体更耐受，未出现死亡，抗氧化酶活性和能量消耗均无显著变化。本地巴西牡蛎幼体死亡率较低，与非本地太平洋牡蛎幼体相比，在较高温度下生化变化不太明显。成年巴西牡蛎对测试温度反应最小。本研究获得的结果为不同牡蛎物种生命阶段对热应激的生理和生化耐受性带来了有趣的新见解。本地物种巴西牡蛎显示出在较高温度下维持生化性能的能力，其生化变化比非本地物种不那么明显。引入的（太平洋牡蛎）表现得更敏感，出现生化变化以应对温度升高。尽管观察到引入物种对接近本地物种自然经历温度的适应性较低，但太平洋牡蛎应对较高温度的能力仍应引起对本地物种巴西牡蛎管理和保护的关注。
