大亚湾核电站温排水对区域浮游生物影响效应研究

Global warming could influence marine ecosystems by reducing biodiversity and productivity and causing environmental disasters. Many studies have observed such phenomenon in temperate zone. There is no systematic monitor data and studies in tropic and subtropic zone so far and it is still difficult to evaluate such influence clearly on global level. However, many nuclear power plants in these zones provide long-term monitor record on the surrounding environment and biota, and their thermal effluent could be a "suitable experimental site" to detect the effects of seawater temperature increase to ecosystem. Planktons are good indictors to forecast the response of ecosystem to environmental temperature change due to their short life cycle. Based on such understanding, this program will deeply study the ecosystem response to seawater temperature increase caused by the nuclear power plants effluent in Daya Bay. We plan to conduct transects investigations and simulation experiments combined with the synthetically analysis of the long-term monitor record (1982-). Molecular biological and bio-optical techniques will be employed to detect the physiological and ecological responses of plankton to seawater temperature increase, including plankton biodiversity, population shift, gene expression, photosynthesis physiology, zooplankton feeding transfer and so on. Then, the effects of seawater temperature increase to ecosystem will be synthetically considered, including primary productivity, flux and paths along food chain. This program is anticipated to provide scientific data and improve the ecological understanding on global warming effects and nuclear power safety, and so that it will be helpful to government administration.

全球变暖导致了温带海洋生物多样性与生产力下降、环境灾害频发，显著影响了其生态系统的稳定与健康，但在热带与亚热带海域却缺乏长期系统的研究。核电站温排水会造成区域海水升温，可为相关研究提供"天然试验场"，其观测积累更便于探讨生态系统的变化趋势。浮游生物生命周期短，对温度变化敏感，对预测海洋生态系统发展趋势具有良好的指示作用。因此，本项目分析大亚湾长期（1982-）监测资料的基础上，通过现场调查和模拟试验，结合分子生物学与生物光学技术，检测浮游生物对海水升温的生理与生态响应，包括：浮游生物多样性、光合生理适应与基因表达、桡足类摄食传递变化等，综合探讨水温升高对初级生产、食物链流通途径与效率等过程的影响。通过本研究可为探讨全球变暖对海洋生态系统的影响及其相应响应、国家核电生态安全提供基础资料和理论支持，为政府部门的管理决策提供依据，对丰富海洋生态学理论和完善海洋环境管理也具有一定的指导意义。

全球变暖会直接或间接影响海洋中的生物，从而影响生态系统的稳定性。核电站温排水会造成局部区域海水升温，是进行相关研究的天然试验场。本项目通过对大亚湾历史调查资料分析，发现排水口区域温度是影响浮游植物群落的重要环境因子，夏季尤为明显；因此在夏季对温排水影响区域进行了断面调查，系统研究升温对浮游植物生物量、群落结构、粒级结构及光合生理的影响，并采集现场海水进行温度梯度培养实验，研究不同粒级浮游植物对升温的响应；浮游植物群落及生理的改变可能通过食物链传递影响浮游动物食物获取，因此分不同季节采集浮游动物样品，分析桡足类优势种的现场摄食，比较升温对桡足类摄食影响的种间差异、季节差异，选取桡足类代表种进行温度梯度摄食实验，研究其对升温的响应。结果显示，排水口区域的短暂升温利于浮游植物生长，尤其会刺激赤潮藻类的生长，但高温会抑制其光合生理活性，33℃可能是引起变化的关键阈值温度，不过这些影响会在远离高温区后恢复正常，这对于揭示温排水影响区域赤潮频发的原因具有重要意义；Micro和Nano级浮游植物的高温耐受能力及相应的受损恢复能力均高于Pico级，暗示升温会改变浮游植物粒级结构；升温会影响桡足类的摄食多样性，且呈现种间差异和季节差异，如春季优势种瘦尾胸刺水蚤表现为升温后摄食多样性的增加但驼背隆哲水蚤则相反，夏季优势种红纺锤水蚤摄食多样性降低，说明春季适度升温利于桡足类摄食，但夏季高温则会抑制其摄食；升温也会改变桡足类的食物选择，使其摄食更多的浮游植物，增加对初级生产的摄食压力，这对于春季和夏季多发的赤潮会起到积极的下行控制作用。研究结果同时暗示了升温对浮游动物食性影响的趋势，而这种摄取食物的改变也会影响食物链传递途径和效率