Abstract：
Cyanobacterial harmful algal blooms (cHABs) are pervasive sources of stress resulting in neurotoxicity in fish. A member of the widely distributed Microcystis genus of bloom-forming cyanobacteria, Microcystis wesenbergii can be found in many freshwater lakes, including Dianchi Lake (China), where it has become one of the dominant contributors to the lake\'s recurrent blooms. However, unlike its more well-known counterpart M. aeruginosa, the effects of dense non-microcystin-containing M. wesenbergii blooms are seldom studied. The disturbance of appetite regulation and feeding behaviour can have downstream effects on the growth of teleost fish, posing a significant challenge to aquaculture and conservation efforts. Here we examined the effects of M. wesenbergii blooms on the food intake of Acrossocheilus yunnanensis, a native cyprinid in southern China. This fish species has disappeared in Dianchi Lake, and its reintroduction might be negatively affected by the presence of this newly-dominant Microcystis species. We co-cultured juvenile A. yunnanensis with a non-microcystin-producing strain of M. wesenbergii at initial densities between 5 × 104 and 1 × 106 cells/mL and monitored fish feeding behaviour and changes in neurotransmitter and hormone protein levels. High-density M. wesenbergii cultures increased the feeding rate of co-cultured fish, elevating concentrations of appetite-stimulating signalling molecules (Agouti-related protein and γ-aminobutyric acid), while decreasing inhibitory ones (POMC). These changes coincided with histopathological alterations and reduced somatic indices in brain and intestinal tissues. Given this potential for detrimental effects and dysregulation of food intake, further studies are necessary to determine the impacts of chronic exposure of M. wesenbergii in wild fish.
摘要：
蓝细菌有害藻华(cHAB)是导致鱼类神经毒性的普遍应激源。水华形成蓝细菌的广泛分布的微囊藻属的成员，在许多淡水湖中都可以找到微囊藻，包括滇池（中国），在那里，它已经成为湖泊反复开花的主要贡献者之一。然而,与更著名的铜绿假单胞菌不同，很少研究致密的不含微囊藻毒素的M.wesenbergii花的影响。食欲调节和摄食行为的干扰会对硬骨鱼的生长产生下游影响，对水产养殖和保护工作构成重大挑战。在这里，我们研究了M.wesenbergii花对云南Acrossocheilus食物摄入量的影响，中国南方的一种土生土长的鲤鱼。这种鱼已经在滇池消失了，这种新优势微囊藻的存在可能会对其重新引入产生负面影响。我们以5×104至1×106细胞/mL的初始密度与不产生微囊藻毒素的M.wesenbergii菌株共培养，并监测鱼类的摄食行为以及神经递质和激素蛋白水平的变化。高密度的韦森贝吉分枝杆菌培养物提高了共养殖鱼的摄食率，提高食欲刺激信号分子（Agouti相关蛋白和γ-氨基丁酸）的浓度，同时减少抑制性（POMC）。这些变化与脑和肠组织的组织病理学改变和躯体指数降低相吻合。鉴于这种潜在的有害影响和食物摄入失调，进一步的研究是必要的，以确定长期暴露的野生鱼类的影响。
