Lek E, Platell M E, Fairclough D V, Hall N G, Potter I C
Centre for Fish and Fisheries Research, Murdoch University, Murdoch 6150, WA, Australia.
Science and Resource Assessment Directorate, Fisheries, Department of Sustainability and Biosecurity, Department of Primary Industries and Regional Development, 39 Northside Drive, Hillarys WA 6025, Australia.
J Fish Biol. 2018 Apr;92(4):901-928. doi: 10.1111/jfb.13541.
Contemporary multivariate statistics were used to test the hypotheses that the dietary compositions of three populations of labrids on the west Australian coast are related to body size and undergo seasonal changes and to elucidate the relative extents and basis for any dietary differences within and between those populations. Gut content analyses determined the dietary compositions of Choerodon rubescens in marine waters of the outer reefs in the World Heritage Area of Shark Bay (26° S; 114° E) and of Choerodon schoenleinii in inner protected reefs of that large embayment. The dietary compositions of C. rubescens and C. schoenleinii differed significantly among length classes, progressed serially with increasing body size, both overall and almost invariably in each season and were more closely related to body size than season, whose effect was at best minimal. The size-related dietary change in C. rubescens involved, in particular, a shift from crustaceans and non-mytilid bivalves to mytilid bivalves and echinoid echinoderms. Although the diet of C. schoenleinii followed similar size-related changes, it contained a greater volume of gastropods when the fish were small and mytilids when large and only a small volume of echinoids. The dietary composition of C. rubescens in the Abrolhos Islands, 300 km to the south of Shark Bay, was related both to length class and season and differed from that of this labrid in Shark Bay with the ingestion of lesser volumes of mytilids and greater volumes of echinoids. The size-related changes in diet imply that these species shift from foraging over soft substrata to over reefs as their very well-developed jaws become sufficiently strong to remove attached and larger prey. The dietary compositions of C. rubescens and C. schoenleinii in Shark Bay and of C. rubescens at the Abrolhos Islands were related far more to habitat-locational differences than to length class and season. The above intraspecific and interspecific differences in diet are consistent with qualitative accounts of the relative abundances of the main prey in their respective environments, supporting the view that, despite specializations in their feeding apparatus, these labrids can feed opportunistically to a certain extent and could thus potentially respond to moderate changes in the composition of their prey caused by climate change and other anthropogenic effects.
西澳大利亚海岸三种隆头鱼种群的饮食组成与体型相关且会发生季节性变化，并阐明这些种群内部以及种群之间饮食差异的相对程度和依据。肠道内容物分析确定了位于鲨鱼湾世界遗产区（南纬26°；东经114°）外礁海域的红鳍笛鲷以及该大港湾内受保护内礁的勒氏笛鲷的饮食组成。红鳍笛鲷和勒氏笛鲷的饮食组成在不同体长组之间存在显著差异，总体上以及几乎在每个季节都随着体型增大而依次变化，并且与体型的关系比与季节的关系更为密切，季节的影响充其量是微乎其微的。红鳍笛鲷与体型相关的饮食变化尤其涉及从甲壳类动物和非贻贝类双壳类动物向贻贝类双壳类动物和海胆类棘皮动物的转变。尽管勒氏笛鲷的饮食遵循类似的与体型相关的变化，但当鱼较小时其食物中腹足类动物的比例较大，当鱼较大时则贻贝类动物的比例较大，而海胆类动物的比例较小。位于鲨鱼湾以南300公里处的阿伯罗霍斯群岛的红鳍笛鲷的饮食组成既与体长组有关，也与季节有关，并且与鲨鱼湾的这种隆头鱼不同，其摄入的贻贝类动物数量较少，海胆类动物数量较多。饮食中与体型相关的变化意味着这些物种随着其发育良好的颌变得足够强壮以捕食附着的和更大的猎物，从在软底质上觅食转变为在珊瑚礁上觅食。鲨鱼湾的红鳍笛鲷和勒氏笛鲷以及阿伯罗霍斯群岛的红鳍笛鲷的饮食组成与其栖息地位置差异之间的关系远比与体长组和季节的关系更为密切。上述种内和种间的饮食差异与它们各自环境中主要猎物相对丰度的定性描述一致，支持了这样一种观点，即尽管这些隆头鱼在摄食器官上有专门化，但它们在一定程度上可以机会性觅食，因此可能对气候变化和其他人为影响导致的猎物组成的适度变化做出反应。
