利用耳石信息探究乌伦古湖东方欧鳊栖息生境与其生长的关系

Over-exploitation of water resources lead to the inflow reduction and ecological environment deterioration of Ulungur Lake, and caused the resource of common bream to dramatically decline. Hence, close attention should be paid to the conversation of its population. Previous studies showed that, the habitats in different water areas of Ulungur Lake were different, and there were significant differences between the growth rates of bream from different parts of the lake. Therefore, probe into the relationship between the habitat and growth of bream is particularly important to its population conservation. In this project, we plan to use otoliths to investigate the spatial distribution pattern of the growth characteristic of bream in Ulungur Lake. Use otolith element analysis to investigate the variations in habitats of different growth stages (larval, juvenile, sub-adult and adult stages) of bream from different parts of the Ulungur Lake base on contrastive analysis of the composition and contents of microelements between micro-regions of otoliths and water bodies. On this basis, we will clarify the relationships between the habitat and growths of bream, and identify the key factors that affect their growth. Implementation of this project will deepen our understanding of the behavioristics and ecology of bream, and help provide reliable evidence for conservation of the bream stocks in the Ulungur Lake, provide technical supports for artificial breeding, transplantation, and domestication of bream. Meanwhile, it will also provide theoretical basis for long-term monitoring of water environment using otolith element analysis technique.

水资源过度开发造成乌伦古湖入水量减少，生态环境恶化，进而导致东方欧鳊资源量明显下降。资料显示，乌伦古湖不同水域生境条件各异，且前期研究表明，不同群体的东方欧鳊生长差异明显。因此，探究栖息生境与东方欧鳊生长之间的关系对其资源的合理保护和利用显得尤为重要。本项目拟以耳石为材料，研究乌伦古湖东方欧鳊生长特性的分布格局。并利用耳石微量元素分析，对不同群体东方欧鳊耳石微区与水体中的元素组成及含量进行对比分析，明确东方欧鳊不同生长期（仔鱼期、（稚）幼鱼期、亚成鱼期及成鱼期）所经历的生境变化。在此基础上，综合分析栖息生境与其生长之间的关系，查明影响其生长的关键因子。本研究将进一步加深对东方欧鳊行为学和生态学的认知，有助于乌伦古湖东方欧鳊资源保护和利用，也将为东方欧鳊的人工养殖及移植驯化提供技术支持。同时，还将为耳石元素分析用于水环境长期监测提供理论依据。

东方欧鳊为新疆乌伦古湖主要经济鱼类之一，过度捕捞，以及水资源过度开发引起的湖区生态环境恶化，导致其渔产量急剧下降。本项目以2019年5-7月、11月-12月以及2020年10月在乌伦古湖采集了808尾东方欧鳊样本，对乌伦古湖东方欧鳊生物学特性进行研究，并基于鱼类耳石和不同区域水体中的化学元素组成分析，阐明了东方欧鳊不同生活史阶段适宜栖息生境及其与生长的关系，明确影响其生长的关键因子。结果表明：耳石为东方欧鳊最佳的年龄鉴定材料；乌伦古湖东方欧鳊退算及实测体长von Bertalanffy生长方程分别为：Lt = 348.6 (1-e-0.123(t+0.205)) 和 Lt = 338.5 (1-e-0.139(t+0.473))，生长拐点年龄为9龄，体长234.3 mm；绝对繁殖力为77311 ± 5461粒/尾，相对繁殖力为162 ± 7粒/g；雄鱼初次性成熟年龄及体长分别为6.6龄及177 mm，雌鱼最小性成熟年龄及体长分别为7.6龄及216 mm；东方欧鳊为偏动物食性的广食性鱼类，主要摄食水生昆虫幼虫。研究结果表明，东方欧鳊生长率受水温、水体大小、营养生态位宽度、个体发育阶段的食性变换、成鱼阶段食物的易得性以及环境条件等因素的影响，其中，饵料丰度是影响东方欧鳊生长的关键性因子。本研究进一步丰富了我国冷水性鱼类生态学研究资料，为东方欧鳊种群资源保护及增养殖技术发展提供科学依据。