嘉陵江中游银鮈食物组成及肠道异速生长模式初步研究

Preliminary Study on Food Composition and Intestinal Allometric Growth Pattern of Squalidus argentatus in Midstream of the Jialing River

【目的】研究银鮈(Squalidus argentatus)食物组成与其肠道异速生长的关系,探讨其生态适应性。【方法】在嘉陵江中游苍溪江段采集银鮈共计46尾,分析其食物组成和肠道异速生长模式。【结果】银鮈整体肠道盘曲方式简单,呈"S"型,其前肠、中肠、后肠在长度、质量、发达程度等方面均存在显著差异。异速生长方程结果表明,银鮈前肠和整体肠道均存在异速生长,从拐点前的快速生长转变为等速生长,而中肠保持快速生长,后肠保持等速生长。食性分析结果表明,银鮈的食物主要由有机碎屑、硅藻、淡水壳菜、摇蚊幼虫等多种类型组成,其食物来源广泛,属于杂食性鱼类。以前肠拐点为分组依据,拐点前(24尾)银鮈主要摄食有机碎屑(质量百分比76.84%),其次是摇蚊幼虫(21.16%)和硅藻(1.77%);而拐点后(22尾)有机碎屑对银鮈食物贡献最大(90.41%),其次为淡水壳菜(6.64%)和硅藻(1.18%)。【结论】银鮈属杂食性鱼类,其前肠与整体肠道表现出异数生长模式,这可能与其对摄入食物的消化和吸收有关。

【Objectives】Study on the relationship between food composition and intestinal allogeneic growth of Squalidus argentatus so as to explor of its ecological adaptation.【Method】A total of 46 S.argentatus were collected from the Cangxi reaches in midstream of the Jialing River to analyze their food composition and intestinal allometric growth pattern.【Result】The intestinal circling pattern of S.argentatus was simple,which showed S-shape.The foregut,midgut,and hindgut were different significantly in length,quality and development degree.The results of the allometric growth equation showed that there were allometric growth in the foregut and the whole intestine of S.argentatus,which changed from rapid growth (before the inflection point) to constant growth.While the midgut always maintained rapid growth,and the hindgut maintained constant growth.Diet analysis showed that the main diet of S.argentatus was composed of various food categories,including organic detritus,diatoms,freshwater moule (Limnoperna lacustris),and chironomidae larvae.Due to the various food sources,the S.argentatus was defined as omnivorous fish.S.argentatus was grouped according to the inflection point of foregut.Before the inflection point,organic detritus (Percentage of weight=76.84%),chironomidae larvae (21.16%),and diatoms (1.77%) were the main food for S.argentatus (24 individuals).However,after the inflection point,organic detritus (90.41%) was the most important food category for S.argentatus (22 individuals),followed by L.lacustris (6.64%) and diatom (1.18%).【Conclusion】S.argentatus belongs omnivorous fish,its foregut and whole intestine show allometric growth pattern which may be closely related to the prey digestion and absorption.