Conservation of freshwater wildlife in Hong Kong: A genetic perspective

Freshwater fauna is highly threatened owing to various human disturbances and a lack of natural connectivity among populations. Immediate conservation actions are vital to save freshwater wildlife from population decline and extinction. Given the paucity of resources, conservation prioritization is essential to guide resource allocation for effective and practical management; however, the incorporation of quantitative ranking approaches in population genetic studies is highly limited. This study scrutinized the genetic diversity and examined the population structure of three invertebrates (the atyid shrimp Caridina cantonensis, the pachychilid snail Sulcospira hainanensis, the palaemonid shrimp Macrobrachium hainanense) and five fishes (the Chinese barb Barbodes semifasciolatus, the paradise fish Marcopodus opercularis, the Hong Kong paradise fish Macropodus hongkongensis, the Beijiang thick‐lipped barb Acrossocheilus beijiangensis, and the rosy bitterling Rhodeus ocellatus) in Hong Kong, based on mitochondrial cytochrome c oxidase subunit I gene and control region, respectively. In general, the three fish species of conservation concern (M. hongkongensis, A. beijiangensis, and R. ocellatus) showed low to no genetic diversity while the other species showed high genetic diversity and strong population differentiation. This study also investigated the use of Heightened Evolutionary Distinctiveness (HED) estimation on quantitatively prioritizing the 95 populations for conservation, including three previously studied species (the white cheek goby Rhinogobius duospilus, the sucker‐belly loach Pseudogastromyzon myersi, and the striped loach Schistura fasciolata). Only five sites had relatively high normalized HED values (>0.70) for all taxa occurring there, and thus are of relatively higher conservation priority. Many sites harboured evolutionarily distinct populations for only one to three species; therefore, a general plan for all freshwater inhabitants cannot be formulated. This comprehensive comparative study highlights the importance of genetic attributes in conservation decision making and sheds light on plausible conservation management in Hong Kong and other highly developed areas with significant freshwater biodiversity.