Department of Environmental Science and Policy, University of Milan, Via Celoria 2, 20133, Milan, Italy.
Parco Nazionale Gran Paradiso, Via Pio VII 9, 10135, Turin, Italy.
Fish Physiol Biochem. 2024 Apr;50(2):721-732. doi: 10.1007/s10695-024-01301-0. Epub 2024 Jan 19.
In fish, interspecific interactions between nonnative and other sympatric species are considered determinants in shaping species assemblages. Such interactions can also arise between nonnative fish species only, including salmonids such as the brown trout (Salmo trutta, Linnaeus, 1758) and the rainbow trout (Oncorhynchus mykiss, Walbaum, 1792), returning contrasting outcomes. The present manipulative experiment was aimed at exploring the effect of interspecific competition on the body growth and the oxidative status of parr (2 + -year-old individuals) of the brown trout and the rainbow trout. Allopatric (intraspecific competition) and sympatric (interspecific competition) populations of these species were experimentally recreated in two wild streams. At the end of a 2-month-long experiment, changes in specific growth rate (SGR), oxidative status (i.e., levels of reactive oxygen species and activity of antioxidant enzymes such as superoxide dismutase - SOD, catalase - CAT and glutathione peroxidase - GPx) and oxidative damage (i.e., lipid peroxidation) were investigated in brown and rainbow trout individuals maintained in allopatric or sympatric populations. Sympatric interactions between rainbow and brown trout parr resulted in a significant decrease in SGR of brown trout individuals only. Moreover, an overall modulation of the oxidative status, in terms of an increase in ROS levels coupled with the activation of SOD and CAT activity, occurred in brown trout individuals under sympatric conditions. These findings might suggest that, under sympatric conditions, parr of the rainbow trout are more competitive than brown trout for food acquisition. However, this competition affected the antioxidant defenses of the brown trout only, probably because of reduced ingestion of dietary antioxidants or increased physical activity and aggressive behavior. Thus, interspecific interactions can induce physiological and phenotypic effects on parr of nonnative salmonids, with potential consequences on the establishment of populations of these species in freshwater ecosystems.
在鱼类中，非本地种与其他同域种之间的种间相互作用被认为是形成物种组合的决定因素。这种相互作用也可能仅在非本地鱼类物种之间发生，包括鲑鱼，如褐鳟（Salmo trutta，Linnaeus，1758）和虹鳟（Oncorhynchus mykiss，Walbaum，1792），产生相反的结果。本实验旨在探索种间竞争对褐鳟和虹鳟幼鱼（2+龄个体）的身体生长和氧化状态的影响。通过实验在两条野生溪流中重现了这些物种的异域（种内竞争）和同域（种间竞争）种群。在为期 2 个月的实验结束时，研究了在同域或异域种群中饲养的褐鳟和虹鳟个体的特定生长率（SGR）、氧化状态（即活性氧物种水平和抗氧化酶活性，如超氧化物歧化酶-SOD、过氧化氢酶-CAT 和谷胱甘肽过氧化物酶-GPx）和氧化损伤（即脂质过氧化）的变化。虹鳟和褐鳟幼鱼的同域相互作用导致褐鳟个体的 SGR 显著下降。此外，在同域条件下，褐鳟个体的氧化状态发生了整体调节，表现为活性氧物种水平升高，同时 SOD 和 CAT 活性激活。这些发现表明，在同域条件下，虹鳟幼鱼比褐鳟幼鱼更具竞争力，能够更有效地获取食物。然而，这种竞争仅影响了褐鳟的抗氧化防御系统，可能是因为褐鳟摄入的膳食抗氧化剂减少或增加了身体活动和攻击行为。因此，种间相互作用会对非本地鲑鱼的幼鱼产生生理和表型影响，可能对这些物种在淡水生态系统中的种群建立产生潜在影响。
