盐度对企鹅珍珠贝足丝分泌的影响

企鹅珍珠贝（Pteria penguin）是生产附壳珍珠的大型海水经济贝类，其依靠强壮的足丝将自身固定在硬质基底上，抵抗水流的冲击和抵御被捕食等。足丝分泌和足丝的形状很容易受到环境的影响，本实验采用盐度30为低盐度组、盐度35为中盐度组和盐度40为高盐度组，研究这3种盐度对企鹅珍珠贝足丝分泌、足丝直径和足丝拉力的影响，通过单因素方差分析法（LSD法）分析这三个足丝相关指标在3种盐度组间是否存在显著性差异。结果显示，3种盐度下企鹅珍珠贝足丝附着率无显著差异，但在整个实验周期72 h内，中盐度组的足丝分泌总数为（48.7 ± 15.1）根，显著高于低盐度组的（24.7 ± 5.0）根和高盐度组的（13.3 ± 1.5）根。在实验的前6 h内，中盐度组的足丝首次附着率显著高于低盐度组和高盐度组（P < 0.05），但在后续的12 h、18 h、30 h、42 h、54 h和66 h这6个时间点，3个盐度组的足丝首次附着率均无显著性差异。足丝直径未受盐度变化的影响，但盐度对足丝拉力具有显著影响，中盐度组的足丝拉力显著高于低盐度组和高盐度组（P < 0.05）。上述结果表明，企鹅珍珠贝为适应一定范围内盐度的改变，会在短时间内通过抑制足丝分泌来减少能量消耗，随着对环境的适应足丝分泌会恢复。盐度影响足丝分泌且对足丝拉力影响显著，但对足丝直径无明显影响。本研究可以为企鹅珍珠贝养殖及珍珠插核培育提供理论基础。

Effect of Salinity on Byssus Secretion of Pteria penguin

Objectives] The winged pearl oyster (Pteria penguin) is one of the large marine economic molluscs that are used to produce mabé pearls. It relys on strong byssus to anchor itself to substrate and resist the impact of water flow and predators. The byssus secretion behavior and byssal properties are easily affected by the environmental factors. Therefore, this research aims to study the effect of salinity on byssus secretion and mechanical properties of P. penguin. Methods] In this experiment, three different salinities (low salinity group of 30, control salinity group of 35, high salinity group of 40) were used to study the effects of different salinities on byssus secretion, diameter and breaking force of P. penguin. Mustcam USB digital microscope was used for measuring and recording the diameters of the proximal, middle and distal regions of newly secreted byssus to an accuracy of 0.01 mm. Tensile tester (HP-10, Handpi) was used for byssus breaking force determination without affecting the structural properties of the byssus. One-way ANOVA (LSD method) was used to analyze whether there were significant differences for the three byssus-related parameters among the three salinity groups. Results] The results showed that there were no significant differences in the byssus attachment rates of P. penguin among different salinity groups (Fig. 2), but the total number of byssus secretion in the control salinity group (48.7 ± 15.1) was significantly higher than that in the low salinity group (24.7 ± 5.0) and the high salinity group (13.3 ± 1.5) throughout the whole experimental period of 72 h. During the first 6 h of the experiment, the byssus first attachment rate in the control salinity group was significantly higher than that in the low salinity and high salinity groups (P < 0.05), but no significant difference was identified in the following hours (12 h, 18 h, 30 h, 42 h, 54 h and 66 h) in the byssus first attachment rate in the three salinity groups (Fig. 3). The measurement results of byssus diameter showed that the distal diameter of byssus was significantly different from the middle or proximal diameter (P < 0.05) under the same salinity. Therefore, when investigating the effect of salinity on the diameter of byssus, the whole byssus was still divided into three parts. There was no significant difference in the diameter of the same part (proximal, middle and distal diameter) of the byssus under 3 different salinities (Fig. 4), while salinity had significant effects on the byssus breaking force (Fig. 5), and the byssus breaking force in the control salinity group was significantly higher than that in the low salinity and high salinity groups (P < 0.05). Conclusion] The above results show that in high salinity of 40 or low salinity of 30, byssus secretion is inhibited in the initial stage, probably due to the need to close the shell and reduce energy consumption to adapt to the environment. There is no significant difference in the first attachment rate among the three salinity groups. Salinity significantly affects the byssus re-attachment rate and breaking force, but not the byssus diameter. This study would provide valuable information for P. penguin culture and nucleus-inserting and pearl production.