胶州湾海洋生态系统国家野外研究站知识库

随着贝类养殖规模的逐年扩大，要想提高养殖效益，对贝类自身调节机制的研究必不可少。在贝类养殖生态系统中，贝类的下行控制作用是非常关键的环节，贝类摄食完成了物质和能量由生产者向更高营养级的传递。通过对贝类下行控制作用的研究，可以为贝类养殖活动提供更多的参考。

本文在对贝类滤水能力相关研究的基础上，设计围隔实验，以菲律宾蛤仔和长牡蛎作为研究载体，通过测定在不同养殖密度下，培养围隔水体中营养盐循环、浮游植物群落结构、微型浮游生物以及水体环境因子的时间变化，以此揭示了养殖贝类下行控制作用的相关机制；同时借助一些对营养盐施肥的相关研究，以稻壳灰作为硅酸盐肥料，探究施加硅肥对贝类养殖的影响；另外针对一些学者提出的贝类作为“生物滤器”的观点，进一步做了围隔实验验证，探究贝类养殖用来去氮和缓解富营养化的可行性。主要结果如下：

养殖贝类对水体中营养盐的下行调控主要体现在氮盐的累积和硅酸盐的消耗上。贝类摄食水体中浮游植物以及形成生物沉积物，加强硅从水体中的流失，在有菲律宾蛤仔或牡蛎养殖的围隔内，其水体中硅酸盐含量减少量是对照组的两倍还多；同时通过呼吸代谢作用，增加氨氮的释放，造成养殖水体中氮富余和硅缺乏，营养盐结构的改变，增加了养殖水体出现硅酸盐限制的风险。通过施加硅肥，有效向水体中补充硅酸盐，缓解硅限制的发生。

养殖贝类的下行控制作用，主要是通过贝类的摄食实现的。贝类摄食水体中浮游植物和颗粒有机物质，明显降低水体中浮游植物丰度，养殖密度差异是主要的影响因素，高密度养殖显著清除水体中浮游植物生物量，十天内可以清除浮游植物总生物量的70%，叶绿素水平的变化与之相一致。其次，贝类对浮游植物的下行控制作用还体现在群落结构的改变上，牡蛎选择性摄食，浮游植物群落结构表现为由甲藻优势向硅藻优势转变的趋势，特别是在高牡蛎密度养殖组，实验结束时甲藻被消耗殆尽，硅藻大量增殖，生物量增长了近万倍。再次，对浮游植物种群优势度分析的结果显示，养殖水体中的优势种由原先的纤细原甲藻（Prorocentrum gracile），在实验中期变成扁压原甲藻（Prorocentrum compressum），到了实验后期新月柱鞘藻（Cylindrotheca closterium）成指数式增殖，成为了新的优势种，浮游植物粒径的变化出现了小型化的趋势。同时，稻壳灰肥料的添加，促进了这种进程的发生。

我们分析了贝类养殖过程中，对水体溶解氧和pH的影响，贝类呼吸代谢消耗水中溶解氧，降低DO和pH水平，并使水体呈弱酸化；稻壳灰施肥有效改善养殖环境。

由于贝类的选择性摄食，对于粒径较小的物质难以滤食，贝类摄食作用对微型浮游生物群落的影响较小，但微型浮游生物对营养盐的变化较敏感，贝类下行控制作用通过调节营养盐循环，间接影响nano级浮游生物和异养细菌的增殖。

我们的研究结果支持贝类作为“生物滤器”的观点，即贝类养殖活动可以去除水体中多余的氮，缓解氮富营养化的发生。单纯的贝类养殖虽然可以做到对水体中氮的去除，但是效果甚微，同时，在高密度养殖下，去除的氮并不能被贝类所利用，大部分都转移到了沉积物中。稻壳灰施肥可以增强氮去除效果，提升贝类生长量，增加养殖效益。

As shellfish breeding scale expanded year by year, to improve the breeding benefit, the study of shellfish self-regulatory mechanism essential. In shellfish aquaculture ecosystem, the top-down control of shellfish is key link, shellfish ingestion completes the transformation of matter and energy. Through the study of the top-down control of shellfish, we can provide more references for shellfish culture.

This paper is based on the research on the water filtration capacity of shellfish, an enclosure experiment is designed, the Ruditapes philippinarum and crassocrassia gigas were used as research vectors. The temporal variation of nutrient cycles, phytoplankton community structure, nannoplankton and water environmental factors were determined under different breeding densities, the relevant mechanisms of top-down control of cultured shellfish were revealed in microform. At the same time, with the help of some studies on nutrient fertilization, using rice husk ash as silicate fertilizer, to explore the effect of applying silicon fertilizer on shellfish culture. In addition, some scholars put forward the idea of shellfish as a biofilter, further enclosure experiments were carried out to verify the feasibility of using shellfish culture to remove nitrogen and alleviate eutrophication. The results as follow:

The top-down control of nutrient salt in water by cultured shellfish is mainly reflected in the accumulation of nitrogen salt and the consumption of silicate. Shellfish feed on phytoplankton and form biogenic sediments that reinforce the loss of silicon from the water. At the same time, the release of ammonia salt was increased through respiration and metabolism, resulting in nitrogen surplus and silicon deficiency, the change of nutrient salt structure increases the risk of silicate limitation in aquaculture water. By applying silicon fertilizer, adding silicate to water effectively, the occurrence of silicon restriction can be alleviated.

The top-down control of cultured shellfish is mainly realized through feeding of shellfish. Shellfish ingested phytoplankton and particulate organic matter in the water, reducing the phytoplankton abundance significantly, the density difference of culture was the main influencing factor, the high density culture significantly cleared the phytoplankton biomass in the water, and the change of chlorophyll level was consistent with it. Secondly, the top-down control effect of shellfish on phytoplankton is also reflected in the change of community structure, due to the selective feeding of shellfish, the phytoplankton community structure showed a trend of changing from dinoflagellates advantage to diatoms advantage. Thirdly, the results of the dominance analysis of phytoplankton population showed that, the dominant species in the cultured water was replaced by the Prorocentrum compressum in the middle of the experiment, which was Prorocentrum gracile original，at the end of the experiment, Prorocentrum compressum proliferated exponentially and became a new dominant species, there was a trend of miniaturization of phytoplankton particle size. At the same time, the addition of rice husk ash fertilizer promoted this process.

We analyzed the effects of shellfish culture on dissolved oxygen and pH in water. The respiration and metabolism of shellfish consumed dissolved oxygen in water, reduced DO and pH levels, and make the water In weak acidic. Rice husk ash fertilization can effectively improve the breeding environment.

Due to the selective feeding of shellfish, it is difficult to filter the material with small particle size, and the feeding effect of shellfish has little effect on the microplankton community. However, the microplankton is sensitive to the change of nutrient salts, and the top-down control of shellfish indirectly affects the proliferation of Nanoplankton and Heterotrophic bacteria by regulating nutrient salts circulation.

Our results support the view that shellfish act as biofilters, that is, shellfish culture activities can remove excess nitrogen from water and alleviate the occurrence of nitrogen eutrophication. Although pure shellfish culture can remove nitrogen from water, it has little effect, at the same time, in high-density farming, the nitrogen removed is not used by the shellfish, and most of it is transferred to the sediment. Rice husk ash fertilization can enhance the nitrogen removal effect, improve the growth of shellfish, increase the efficiency of cultivation.

第1章 引言. 1

1.1 养殖贝类的下行调控效应. 1

1.2 贝类养殖缓解富营养化的争议. 3

1.3 贝类养殖系统的生态调控. 4

1.4 研究目的和意义. 6

第2章 贝类养殖对浮游植物的下行控制作用. 7

2.1 材料与方法. 7

2.1.1 实验材料与设备. 7

2.1.2 实验设计. 8

2.1.2.1 菲律宾蛤仔实验. 8

2.1.2.2 长牡蛎实验. 8

2.1.3 样品采集与测定. 9

2.1.4 数据分析. 10

2.2 结果. 10

2.2.1 菲律宾蛤仔实验. 10

2.2.1.1 蛤仔生长状况. 10

2.2.1.2 叶绿素a的变化. 11

2.2.2 长牡蛎实验. 11

2.2.2.1 浮游植物丰度随时间变化. 11

2.2.2.2 浮游植物群落结构的响应. 14

2.2.2.3 对微型浮游生物群落的影响. 16

2.3 讨论. 17

2.4 小结. 19

第3章 贝类养殖对营养盐的影响. 21

3.1 实验方法. 21

3.1.1 样品处理与分析. 21

3.1.2 数据分析. 21

3.2 结果. 22

3.2.1 菲律宾蛤仔养殖对溶解态营养盐的影响. 22

3.2.2 菲律宾蛤仔养殖对营养盐结构的影响. 23

3.2.2 不同密度牡蛎养殖下营养盐的变化. 24

3.3 讨论. 26

3.3.1 养殖贝类下行控制作用调节营养盐循环. 26

3.3.1 菲律宾蛤仔摄食对硅酸盐限制的影响. 27

3.4 小结. 28

第4章 纾缓下行控制压力的环境和增殖效果评估. 29

4.1 材料与方法. 30

4.1.1 实验材料与设备. 30

4.1.2 实验方法. 30

4.1.2.1 稻壳灰施肥. 30

4.1.2.2 培养水体中N含量测定. 30

4.1.2.3 牡蛎N含量测定. 31

4.2 结果. 31

4.2.1 稻壳灰施肥对浮游植物的影响. 31

4.2.2 稻壳灰施肥对营养盐的影响. 33

4.2.3 围隔实验中环境因子的响应. 34

4.2.4 培养水体中N收支. 35

4.2.4.1 水体中总氮含量的变化. 35

4.2.4.2 水体中氮的结构组成. 36

4.2.5 牡蛎N收支. 37

4.2.6 围隔内N收支. 40

4.3 讨论. 41

4.3.1 养殖贝类作为“生物滤器”的评估. 41

4.3.2 稻壳灰施肥效果评估. 42

4.4 小结. 43

第5章 结论与展望. 45

5.1 结论. 45

5.2 研究前景及展望. 45

参考文献. 47

致谢. 55

作者简历及攻读学位期间发表的学术论文与研究成果 57