No abstract

In the last few decades, non-native freshwater fishes have been introduced all over the world for economic purposes, including aquaculture and aquarium trade, as well as improvement for wild stocks resulting in adverse environmental and socio-economic effects. The Guangdong province of China is at a high risk of fish invasions owing to its warm and humid climate, abundance of water courses, flourishing aquaculture and ornamental fish trade, and extensive sea ports. A total of 160 non-native freshwater species were introduced in the Guangdong province and 71.9% of them were imported for aquarium purposes. Fourteen species have established self-sustaining populations and 21 species were found in the main river basin of the Guangdong province. Propagule pressure, rapid evolution and abundant resources in the environment were the factors likely to contribute to successful invasion by non-native fishes. The invasion of non-native fishes in the Guangdong province has already resulted in economic losses, decline of native species, as well as negative impacts on the functional diversity of native fish assemblages. To mitigate these effects and prevent future non-native fish invasions, scientists, policy makers and stakeholders should collaborate on the management of non-native fish introductions by developing risk assessments, statutory regulations, public education and scientific research.

China is a major country in turtle cultivation and has a long history of artificial breeding of turtles. In this study, a census and statistical analysis of artificially domesticated aquatic turtles in 15 provinces of China were conducted. The results showed that 29 species were aquatic turtles native to China, accounting for approximately 9% of the world’s total, and a large number of exotic aquatic turtles are also domesticated in China. The present situation of artificial breeding and protection of aquatic turtles in major provinces of China is shown, and existing problems are also put forward, with suggestions for the protection and management of aquatic turtles.

Predicting the ecological impacts of invasive species on analogous native species has great significance for native population conservation. We tested how the strength of interspecific competition from a coexisting invasive species varies with abundance and how this compares with intraspecific competition. The model species was the native mud carp, and the coexisting invasive species was mrigal carp. The replicated mesocosm used each species in an allopatric control (n = 10), in intraspecific competition treatments (n = 20, 30), in a sympatric control (n = 5 for both species) and in interspecific competition treatments (n = 10, 15, 20 for both species). The treatment effects were the specific growth rate (SGR), position and size of trophic (isotopic) niches. Compared to mrigal carp, mud carp had a significantly lower survival rate (median: 0.8) and SGR. The mud carp SGR significantly decreased when the con- and inter-specific densities increased, showing a density dependence, but there was no significant difference between intra- and inter-specific competition. Compared to intraspecific competition in which mud carp expanded their niche, the presence of mrigal carp drove the mud carp trophic niche toward broader sizes at lower trophic positions, but intensified interspecific competition drove the mud carp trophic niche toward constriction. Both mud carp and mrigal carp expanded their niches in invaded communities, and their niches overlapped with each other. Their niche expansions implied plasticity in resource utilization. These results also suggested a complexity in how ilyophagous invasive species integrate into food webs and alter their structure.

In this study, the complete mitochondrial genome of Carassioides acuminatus was first sequenced and annotated. The entire mitogenome is 16,579bp in length, which consists of 13 protein-coding genes (PCGs), 22 transfer RNA genes, 2 ribosomal RNA genes, and a control region (D-loop). The overall nucleotide composition of the C. acuminatus mitochondrial genome shows an obvious anti-G bias. The accuracy of the fresh sequences was verified by phylogenetic analysis. The complete mitochondrial genome of C. acuminatus is useful to population genetics and molecular systematics.