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    营养状态对不同觅食方式鱼类逆境耐受能力的影响

    NUTRITIONAL STATUS ON STRESS TOLERANCE OF FISHES WITH DIFFERENT FORAGING MODES

    • 摘要: 为探究营养状态对不同觅食方式鱼类逆境耐受能力的影响, 本研究选取伏击取食鱼类: 大口黑鲈(Micropterus salmoides, 鲈形目)、南方鲇(Silurus meridionalis, 鲇形目)、鲈鲤(Percocypris pingi, 鲤形目)和积极摄食鱼类: 罗非鱼(Oreochromis niloticus, 鲈形目)、黄颡鱼(Pelteobagrus fulvidraco, 鲇形目)、中华倒刺鲃(Spinibarbus sinensis, 鲤形目)为研究对象, 设置饥饿组(禁食14d)、饥饿对照组(禁食24h)、消化组(饱足投喂后1h)和消化对照组(禁食24h), 分别测定低氧耐受指标临界耗氧率(O2PCRIT)、供氧能力(α)、临界氧分压(PCRIT), 以及热耐受指标临界高温(CTMAX)和临界低温(CTMIN)。结果显示: 营养状态对低氧耐受能力的影响主要依赖于觅食方式, 表现为饥饿导致所有鱼类O2PCRIT和α同步下降(积极摄食鱼类下降幅度更大)最终维持PCRIT稳定; 两种鲇形目鱼类长期栖息于底层缓流或淤泥底质环境, 长期遭遇低氧和食物短缺的双重胁迫, 饥饿后表现出PCRIT显著下降(P<0.01), 低氧耐受能力增强。摄食消化导致积极摄食鱼类O2PCRIT上升幅度更大, α几乎不变, 最终表现为积极摄食鱼类PCRIT上升幅度高于伏击取食鱼类, 摄食后低氧耐受能力下降。营养状态对热耐受能力的影响主要依赖于系统发育背景, 表现为营养状态发生改变时鲇形目鱼类的热耐受响应最为剧烈, 饥饿后CTMAX和CTMIN均显著下降(P<0.05), 摄食后仅南方鲇CTMAX显著下降(P<0.001); 鲈形目鱼类饥饿后CTMAX显著下降(P<0.01), 摄食后CTMIN表现出显著差异(P<0.05); 鲤形目鱼类热耐受响应最为保守, 仅饥饿后CTMIN表现出显著差异(P<0.05)。研究结果揭示了不同觅食方式鱼类应对食物资源波动和环境胁迫时的生理适应策略, 为理解不同觅食方式鱼类在自然水域对环境变化的响应潜力提供了理论依据。

       

      Abstract: To investigate the effects of nutritional status on stress tolerance in fish with different foraging modes, this study selected ambush foragers: largemouth bass (Micropterus salmoides, Perciformes), southern catfish (Silurus meridionalis, Siluriformes), bass carp (Percocypris pingi, Cypriniformes) and active foragers: tilapia (Oreochromis niloticus, Perciformes), yellow catfish (Pelteobagrus fulvidraco, Siluriformes), Qing bo (Spinibarbus sinensis, Cypriniformes) as research subjects, assigned them to starvation group (fasted for 14d), starvation control group (fasted for 24h), digestion group (sampled 1h after satiation feeding), and digestion control group (fasted for 24h), and measured hypoxia tolerance indices, including critical metabolic rate (O2PCRIT), oxygen supply capacity (α), and critical oxygen tension (PCRIT), as well as thermal tolerance indices, i.e., critical thermal maximum (CTMAX) and critical thermal minimum (CTMIN). The results showed that the effect of nutritional status on hypoxia tolerance mainly depended on foraging mode. Starvation induced parallel decrease in O2PCRIT and α in all species, with greater decrease in active foragers, ultimately maintaining PCRIT stable. The two siluriform species, which naturally inhabit slow-flowing or silty bottom environments and frequently suffer from combined hypoxia and food shortage, exhibited a significant decrease in PCRIT after starvation (P<0.01), indicating enhanced hypoxia tolerance. Digestion caused a larger increase in O2PCRIT in active foragers, while α remained nearly unchanged, resulting in a higher increase in PCRIT in active foragers than in ambush foragers, i.e., a greater impairment of hypoxia tolerance after feeding. The effect of nutritional status on thermal tolerance primarily depended on phylogenetic background. When nutritional status changed, siluriform fishes showed the strongest thermal response: both CTMAX and CTMIN decreased significantly after starvation (P<0.05), and only CTMAX of southern catfish decreased significantly after digestion (P<0.001). In perciform fishes, CTMAX decreased significantly after starvation (P<0.01), while CTMIN showed significant differences after digestion (P<0.05). In cypriniform fishes, thermal responses were the most conservative, with only CTMIN showing significant differences after starvation (P<0.05). These findings reveal the physiological adaptation strategies of fishes with different foraging modes in response to food resource fluctuation and environmental stress, providing a theoretical basis for understanding the response potential of fishes with different foraging modes to environmental changes in natural waters.

       

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