大型海藻规模栽培对桡足类休眠卵形成和萌发的影响及其机理研究

China has the most large-scale seaweed cultivation ecosystems in the world. A seaweed farm has highly heterogeneous microhabitats and abundant food for copepods which are key organisms of aquatic ecosystems. An important survival strategy of copepods is the spawning and hatching of resting eggs. Species composition, abundance and hatching of resting eggs in sediments are important factors affecting copepod community structure and its succession. This project will focus on the effect of large-scale cultivation of the red seaweed Gracilaria on copepod abundance and species composition, comparing with the effects of fish and shellfish culture, using the nearby natural sea as a control area. The study site will be the large aquaculture areas in Nan’ao, Shantou City. Sediment traps and in situ plankton emergence trap/chambers will be used to assess the sediment flux of resting eggs and potential recruitment during seaweed cultivation. Morphology and molecular methods will be used to identify species of copepod resting eggs in the sediments, and water and sediment environmental quality will be analyzed. The spatio-temporal distribution of abundance and the potential recruitment into the planktonic community will be evaluated to assess the effect of large-scale seaweed cultivation on the dynamics of copepod resting eggs, seeking to explain the mechanisms behind these effects based on ultrastructure, physiology and biochemistry, and molecular characteristics. The results of this project will help reveal the effect of seaweed cultivation ecosystems on the role of the copepods in coastal biogeochemical processes.

我国拥有世界上最大规模的大型海藻栽培生态系统。海藻场高度异质化的微生境和丰富的食物来源为桡足类提供了良好的栖息场所。桡足类作为水生态系统中的关键类群，其休眠卵的形成和萌发是重要的生存策略，休眠卵在沉积物中的种类组成、丰度和萌发对水体桡足类群落结构及其演替具有重要影响。本项目拟以汕头南澳大型海藻龙须菜规模栽培区为主要研究海域，并对鱼贝类养殖区和自然海区进行调查和比较研究，利用沉积物捕捉器和浮游生物原位萌发装置研究龙须菜栽培过程中休眠卵的沉积通量，利用形态特征和分子生物学方法鉴定休眠卵种类组成，评估休眠卵丰度的时空分布及其对浮游群落的潜在补充量，结合大型海藻栽培过程中和收获前后水环境和沉积环境的变化，在超微结构、生理生化和分子特征上阐释大型海藻规模栽培对桡足类休眠卵形成和萌发的影响及其机理。本项目的开展对揭示大型海藻栽培生态系统的结构功能和桡足类地球化学过程具有重要意义。

我国拥有世界上最大规模的大型海藻栽培生态系统。海藻场高度异质化的微生境和丰富的食物来源为桡足类提供了良好的栖息场所。桡足类作为水生态系统中的关键类群，其休眠卵的形成和萌发是重要的生存策略，休眠卵在沉积物中的种类组成、丰度和萌发对水体桡足类群落结构及其演替具有重要影响。本项目以汕头南澳大型海藻龙须菜规模栽培区为主要研究海域，并对鱼贝类养殖区和自然海区的水环境和浮游动物群落结构进行调查和比较研究，龙须菜栽培区浮游动物种类数和丰度显著高于对照海区，其组成比例和体长频度分布存在显著差异；龙须菜体表附着浮游动物丰度显著高于周围水体浮游动物丰度，猛水蚤在江蓠属体表附着丰度较高。调查发现龙须菜养殖区表层沉积物和柱状沉积物休眠卵潜在补充量显著高于其他海区，休眠卵的丰度主要受到水体桡足类丰度、盐度、水深和沉积物粒径等多种环境因子的影响；利用沉积物捕捉器调查了原位海区桡足类休眠卵的沉积通量，结果表明龙须菜栽培提高了桡足类休眠卵的萌发率，可能是因为龙须菜富含多种活性物质，室内实验显示其抽提液对浮游动物轮虫的生长和繁殖具有促进作用。在养殖池塘利用细基江蓠野外受控实验表明大型海藻显著提高了桡足类休眠卵的潜在补充量。室内观察了不同桡足类休眠卵的形态结构和胚胎发育过程，研究了休眠卵萌发的影响因素。. 研究结果表明大型海藻的规模栽培增加了浮游动物的种类和丰度，提高了桡足类休眠卵的萌发率，沉积物中桡足类休眠卵“卵库”在浮游-底栖耦合中通过物质能量的传递与水体种群形成一个整体，表明了沉积物休眠卵在水体桡足类种群调节和水层-沉积物耦合生物地球化学过程中起着重要作用。. 本项目的开展对揭示大型海藻栽培生态系统的结构功能和桡足类地球化学过程具有重要意义，初步揭示了大型海藻规模栽培对桡足类休眠卵形成和萌发的作用机制。发表论文8篇，其中SCI论文5篇；培养研究生3名，参加学术会议6人次。