应用稳定同位素技术研究崂山湾夏季鱼类群落的摄食生态

Study on feeding ecology of fish community in Laoshan Bay during summer using stable carbon and nitrogen isotopes

崂山湾是黄海沿岸众多海湾之一,也是当前增殖放流的重要水域,研究该区域鱼类群落结构及其食物网结构,有着非常重要的生态意义和实用价值。本研究根据2014年6月和8月在崂山湾海域进行的底拖网调查,分析该海域夏季鱼类群落的优势种组成,并通过测定稳定同位素对其摄食生态进行研究。结果表明,崂山湾夏季鱼类群落的优势鱼种共有10种,包括六丝矛尾鳅虎鱼、中华栉孔鳅虎鱼、红狼牙鳅虎鱼、皮氏叫姑鱼、白姑鱼、小黄鱼、绿鳍鱼、短吻红舌鳎、斑鲨和赤鼻棱鳀;夏季崂山湾不同月份鱼类群落的优势种组成差异较大。各优势鱼种间δ13C值存在显著差异,结合胃含物分析结果表明6月鱼类群落食物的主要来源均为底层饵料,而8月鱼类群落的食物来源则更广泛。崂山湾夏季2个月鱼类群落的优势鱼种间的δ15N值均存在显著差异,最大分别相差4.61‰和3.70‰。崂山湾6月鱼类群落的优势种包括了中营养级鱼类和高营养级鱼类,鱼类群落的平均营养级为3.90,主要是底栖动物食性鱼类;而8月鱼类群落的优势种包括了低营养级鱼类和中营养级鱼类,鱼类群落的平均营养级为3.37,包括浮游动物食性和底栖动物食性2种食性类型,以底栖动物食性鱼类为主。线性回归分析表明崂山湾夏季10种优势鱼种除皮氏叫姑鱼、斑鲨、短吻红舌鳎和绿鳍鱼的营养级与体长无线性相关外,其余优势鱼种的营养级均与体长呈显著的正相关。这主要由于它们随着体长的增加,摄食高营养级的饵料增加,低营养级的饵料减少,自身的营养级也随之升高。

Laoshan Bay is one of numerous gulfs of the Yellow Sea and an important fish enhancement and release area. It is vital for the Yellow Sea fishery resources that carry out proliferation and implement effective fisheries conservation and management in Laoshan Bay ecosystem. Based on bottom trawl survey conducted in Laoshan Bay in June and August 2014, the dominant fish species of fish community during summer were analyzed and their feeding ecology was studied by stable carbon and nitrogen isotopes method. The stable carbon isotope ratio （δ^13C） is often used to assess basal sources in food web with a slight enrichment, while the stable nitrogen isotope ratio （δ^15N） is indicator of trophic level, as a major increase with each trophic level. In terms of the index of relative importance （1R1）, there were 10 dominant species of fish community in Laoshan Bay during summer, including Amblychaeturichthys hexanema, Ctenotrypauchen chinensis, Odontamblyopus rubicundus, Johnius belengerii, Argyrosomus argentatus, Lanmichthys polyactis, Chelidonichthys kumu, Cynoglossus joyneri, Clupanodon punctatus and Thrissa kammalensis. There were significant differences in dominant fish species composition of fish community between two months in summer. The range of δ^13C of dominant fish species ranged from -20.66‰ to -17.53‰ in June and from -21.06‰ to -17.33‰ in August. There were significant differences in δ^13C between dominant fish species. According to δ^13C of this research, combining with results of stomach contents analysis, the results show that the main food source of fish community was benthic prey in June, but the food source of fish community was more extensive in August. The range of δ^15N of dominant fish species was 10.86‰-15.47‰ in June and 9.40‰-13.10‰ in August. There were significant differences in δ^15N between dominant fish species and the biggest difference were 4.61‰ and 3.70‰, respectively. The dominant species of fish community in Laoshan Bay in June included fish with middle trophic level and high trophic level, the mean trophic level of fish community was 3.90, and was mainly benthivores. The dominant species of fish community in Laoshan Bay in August included fish with middle trophic level and low trophic level, the mean trophic level of fish community was 3.37, including zooplankivores and benthivores, mainly benthivores. Linear regression analysis showed that in addition to J. belengerii, C. punctatus, C. joyneri and C. kumu, whose trophic level showed not linear correlation with the length, and the trophic level of rest of the dominant species was significantly positive correlation with the body length. This was mainly because with the increase of body length, they increase feeding on prey with high trophic level, but reduce feeding on prey with low trophic level, and their trophic level also increases.