dos Santos Alejandra Filippo Gonzalez Neves, dos Santos Luciano Neves, Araújo Francisco Gerson
Departamento de Zootecnia e Desenvolvimento Agrossocioambiental Sustentável, Universidade Federal Fluminense, Rua Vital Brasil, 64, Faculdade de Veterinária, Niterói, Brasil.
Rev Biol Trop. 2011 Sep;59(3):1245-55.
Despite being one of the most well-known cichlid fish of importance to artisanal and sport fishing, and among the largest fishes in the Neotropics, data on digestive tract anatomy of peacock basses (Cichla spp.) are largely lacking, especially for non-native populations. In this paper, we describe for the first time the digestive tract morphology of Cichla kelberi, a voracious piscivore that was introduced in the 1950s into an oligotrophic and physically low-complex impoundment in Brazil. Peacock basses were collected between 1994 and 2002 in Lajes Reservoir, through gillnets (25 to 55mm mesh; 20-50 x 2m), seines (10 x 2.5m; 8.0mm mesh), cast nets and angling. All the fishes were kept on ice in the field and then transferred to the laboratory, where they were identified, measured, weighed and dissected for digestive tract analyses. The Index of Relative Importance-IRI was calculated for diet characterization while linear and non-linear regressions were performed to assess growth patterns of four morphological characters related to feeding (e.g. mouth width, mouth height, stomach length and intestine length) and the number of gill rakers during the C. kelberi ontogeny. Most digestive tract structures were directly related to the piscivorous diet of C. kelberi, indicating that peacock bass is a diurnal, bathypelagic and gape-size limited predator that feeds largely on shallow-water prey species within the littoral zone. Mouth width and height grew allometrically (b > 1) with the size of peacock bass, broadening the size range in which prey can be eaten, but especially for predators smaller than -400mm of total length. Differently, stomach and intestine lengths increased isometrically (b = 1), which could constrain prey consumption for adult C. kelberi, especially those at advanced stages of gonadal maturation. The presence of longer-drawn, sharp and furcated gill rakers in C. kelberi may be related to increased prey retention in the resource-limited Lajes Reservoir, but further studies are necessary whether such features are randomly triggered by genetic or phenotypic anomalies, or effectively bring ecological advantages to the predator. In addition to contribute to improve the current biological knowledge on peacock basses, our results can be also useful to further comparisons on whether those morphological features related to feeding will change with transitions on prey consumption by C. kelberi and/or with the particular conditions of the invaded ecosystem.
尽管孔雀鲈是对个体渔业和游钓业至关重要的最知名丽鱼科鱼类之一，也是新热带界最大的鱼类之一，但关于孔雀鲈（Cichla spp.）消化道解剖结构的数据却非常缺乏，尤其是针对非本地种群。在本文中，我们首次描述了凯氏丽鱼（Cichla kelberi）的消化道形态，这种贪婪的食鱼性鱼类于20世纪50年代被引入巴西一个贫营养且物理复杂度低的蓄水池。1994年至2002年间，在拉热斯水库通过刺网（网目25至55毫米；20 - 50×2米）、围网（10×2.5米；网目8.0毫米）、撒网和垂钓采集孔雀鲈。所有鱼在野外保存在冰上，然后转移到实验室，在那里进行鉴定、测量、称重并解剖以分析消化道。计算相对重要性指数 - IRI用于描述食物组成，同时进行线性和非线性回归以评估与摄食相关的四个形态特征（如口宽、口高、胃长和肠长）以及凯氏丽鱼个体发育过程中鳃耙数量的生长模式。大多数消化道结构与凯氏丽鱼的食鱼性饮食直接相关，表明孔雀鲈是一种日间、中层的且受口裂大小限制的捕食者，主要以沿岸带浅水猎物为食。口宽和口高随孔雀鲈大小呈异速生长（b > 1），扩大了可捕食猎物的大小范围，但对于全长小于400毫米的捕食者尤其如此。不同的是，胃长和肠长呈等速生长（b = 1），这可能限制了成年凯氏丽鱼的猎物摄取量，特别是那些处于性腺成熟后期的个体。凯氏丽鱼中存在更长、更锋利且分叉的鳃耙可能与资源有限的拉热斯水库中猎物保留增加有关，但这种特征是由遗传或表型异常随机引发，还是确实给捕食者带来生态优势，还需要进一步研究。除了有助于完善当前关于孔雀鲈的生物学知识外，我们的结果对于进一步比较与摄食相关的形态特征是否会随着凯氏丽鱼猎物摄取的转变和/或被入侵生态系统的特定条件而变化也可能有用。
