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Abstract
Invasive species are a major and growing threat to China’s native freshwater biodiversity. They have caused species extinctions, biodiversity loss, and environmental changes. Mrigal carp (Cirrhinus mrigala), one of the most widespread and invasive of freshwater fish species, now occurs in major rivers throughout southern China. We report the current (to 2017) distribution of mrigal carp throughout southern China, and experiments with temperature, water quality and food availability, that assess possible impacts of this species on populations of native mud carp (C. molitorella)”. In the wild, the mud carp to mrigal carp weight ratio was 1:1.65. Mrigal carp were a dominant species in some rivers of southern China, such as Liuxi River, Zengjiang River and the Zhaoqing section of Xijiang River. Manipulative experiments reveal mrigal carp to be more tolerant of colder temperature, more eutrophic conditions, and lower dissolved oxygen levels than mud carp. In food-limited experiments, mrigal carp displayed no direct aggression towards mud carp, but they did snatch food from them, and excluded them from eating. Mud carp growth was curtailed in the presence of mrigal carp in food-limited treatments, with a growth rate 2.71%, only 17.02% of that in treatments where carp were fed to satiation. In satiation treatments, mrigal carp also grew up to 2.21 times faster than mud carp. Our results indicate that mrigal carp will outcompete mud carp for resources and habitat, and that both its distribution and population will increase in the future.
Disclosure statement
The authors declared that they have no conflicts of interest to this work.
We declare that we do not have any commercial or associative interest that represents a conflict of interest in connection with the work submitted.
Notes on contributors
Fan Dong Yu is a master student who is studying in Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences and Shanghai Ocean University.
Dang En Gu is a researcher of Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences with interests in the Monitoring and management of alien fish species.
Yan Nan Tong is an assistant researcher of Hainan Academy of Ocean and Fisheries Sciences, China, where he worked as a fisheries scientist.
Gao Jun Li is an assistant researcher of Hainan Academy of Ocean and Fisheries Sciences, China, where he worked as a fisheries scientist.
Hui Wei is an assistant researcher of Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, where she worked as an ecologist.
Xi Dong Mu is a researcher of Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, where he worked as a fisheries scientist.
Meng Xu is an assistant researcher of Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, where he worked as an ecologist.
Ye Xin Yang is an assistant researcher of Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, where she worked as a fisheries scientist.
Du Luo is an assistant researcher of Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, where he worked as an ecologist.
Fang Yuan Li is an assistant researcher of Hainan Academy of Ocean and Fisheries Sciences, China, where he worked as a fisheries scientist.
Yin Chang Hu is a professor of Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, where he worked as an ecologist.