人工鱼礁表面粗糙度与海藻附着效果的关系及其机理研究

The relationship between attachment of seaweed and surface coarseness of the artificial reef and its mechanism will be discussed by analyzing the surface structure of the reef, boundary layer on reef surface and the structure of holdfast of seaweed. This project will firstly focus on research into the structure of the surface of artificial reef, the boundary layer on reef surface,the structure of the holdfast of seaweed, and the geometric structure and size of the propagule of seaweed. As a result, size of the structure will be determined, among which the holdfast may has some relationship with the coarse reef; the expression of surface coarseness will be also determined. For the reef with different surface coarseness, the structure of boundary layer of the reef will be found by simulation based on the software of Fluent and tank tests; the distribution pattern of the spore and the sediment will be identified by simulation; experiments will be carried out to analyze the relationship between the attachment and growth of seaweed and the surface coarseness of the reef at conditions of different currents speeds,different sedimentary situations and different grazing pressure. Finally, based on the analysis of the physical and ecological characteristics of different kinds of seaweed and their holdfasts, the structure of boundary layer on the artifical reef, and the sedimentary characteristics of the sediment, the mechanism of the attachment of seaweed and the fixation of the holdfast will be found; meanwhile, the mechanism of the effect of surface coarseness of the artificial reef on the attachment and growth of seaweed will be identified. The findings of this study can provide suggestions in theory on selection of appropriate materials for constructing reef and techniques to process the surface of the reef. These findings can further develop the theory on ecology of seaweed.

本项目从研究人工鱼礁表面微结构、微流态和海藻固着器微结构、海藻繁殖体几何结构和尺度入手，通过综合分析礁体表面物理特征、礁体表面的附面层和海藻固着器结构特征，探索鱼礁表面粗糙度与海藻附着效果的关系及其内在机理。通过分析礁体微结构和海藻附着面微结构，确定二者相关联的微结构尺度范围，建立鱼礁表面粗糙度的物理表征方法；针对不同粗糙度的礁体，一方面基于Fluent软件和水槽试验揭示礁体表面的流场结构及海藻孢子与沉积物在礁体局部流场影响下的分布规律，另一方面在不同水流条件、沉积条件和啃食条件下开展海藻的附着与生长实验，分析海藻附着与生长同礁体粗糙度的关系及规律性。结合各种海藻类群的繁殖体、固着器的物理特性、生态学特性、以及礁体表面的附面层结构和沉积特性，探索出藻类繁殖体的附着机理，固着器的固着机理，揭示礁体粗糙度对藻类附着和生长的影响机理，为鱼礁的选材和表面处理工艺提供理论依据，并创新藻类生态学理论。

目前制作人工鱼礁的材料主要有石块、混凝土、废旧船舶等。迄今已证实表面粗糙的礁体更有利于海藻的附着和生长，但是内在的机理还缺乏研究。藻类孢子或其他繁殖体与礁体表面接触并附着、生长这一过程受诸多因素影响，如礁体表面微结构、藻类繁殖体几何尺度及其运动能力、固着器的微结构、附面层流态、沉积物积累、啃食动物的影响等等，深入了解这些因素，对于人工鱼礁的材料选择和表面处理技术的开发具有重要意义。.主要研究内容：人工鱼礁表面粗糙度表征、微结构与海藻袍子、固着器的关系研究；礁体表面粗糙度（微结构）与附面层流场及其对藻类孢子附着和固着的影响研究；沉积物和啃食对藻体早期发育的影响研究。.取得的重要结果及其意义：（1）确立了鱼礁表面以及假根附着部位的切片方法。该方法的确立，为在不同尺度下进行人工鱼礁表面粗糙度的表征、通过显微观察来探索藻类在鱼礁表面的附着和固着机制奠定了技术基础，也可为其他硬度差别较大的混合材料的切片观察提供技术借鉴。（2）数值模拟和附着实验表明，无鞭毛的繁殖细胞萌发成的幼苗数量受鱼礁表面粗糙度影响显著并在一定范围内呈正相关关系，而自游动孢子的尾孢藻，鱼礁表面粗糙度的影响不显著。这一发现细化了既往对表面粗糙度与海藻附着关系的定性认识。（3）通过显微观察发现，海藻假根是通过细胞变形和不规则排列的途径来适应鱼礁表面微结构的。这一发现的意义在于，可以通过大量观察，得到海藻假根细胞变形和不规则排列的变化极限，从而在假根细胞尺度上找出适宜海藻固着的鱼礁表面粗糙度范围。（4）通过啃食动物摄食与鱼礁表面窝陷尺度关系的初步研究，发现某些啃食动物（短滨螺类）对鱼礁表面窝陷的深度有选择性，而对小于其体宽的窝陷宽度选择性差（需进一步验证）。这表明，在鱼礁表面粗糙度的选择上，需要进一步考虑窝陷形状及窝陷深度等因素，以减少附着藻类被啃食。另外，需要考虑鱼礁的投放环境及时机，以减少沉积物对鱼礁表面窝陷的掩埋从而对藻类生长产生影响。