Effects of dams and their environmental impacts on the genetic diversity and connectivity of freshwater mussel populations in Poyang Lake Basin, China

Abstract

Habitat fragmentation is one of the main threats to biodiversity. Barriers to dispersal caused by anthropogenic habitat alteration may affect phylogeographic patterns in freshwater mussels. Knowledge of the phylogenetic and phylogeographic patterns of unionoids is vital to inform protection of their biodiversity. Here, we assessed influences of dams and their environmental effects on the genetic diversity and population connectivity of a broadly distributed freshwater mussel, Nodularia douglasiae, in Poyang Lake Basin. The results showed high genetic diversity in areas without dams and low genetic diversity in areas with dams. High genetic differentiation and low gene flow were found among the 11 populations. Genetic variation was significantly correlated with dissolved oxygen levels. The observation of low genetic diversity in populations separated by dams indicated that those populations were subjected to genetic erosion and demographic decline because they are disconnected from other populations with higher diversity. High genetic differentiation and low gene flow among the 11 populations could be correlated with anthropogenic habitat alteration. These results indicated that anthropogenic habitat alterations have led to the decline in freshwater mussel diversity. Therefore, we recommend maintaining favourable habitat conditions and connectivity of rivers or lakes, and strengthening study of life histories with host‐test experiments to identify potential host fish species to strengthen the knowledge base underpinning freshwater mussel conservation.

Molecular phylogenetic, population genetic and demographic studies of Nodularia douglasiae and Nodularia breviconcha based on CO1 and 16S rRNA

“…As listed in Supplementary Tables S5 and S6 , previously reported data were retrieved from the NCBI GenBank and added to our final nucleotide sequence alignment sets. The added sequences were the haplotypes of the samples obtained from South Korea 10 , China 4 , 12 , Japan 10 , Russia 20 , and Vietnam 10 for CO1 of N. douglasiae , and from Japan ( N. nipponensis and N. biwae ) and South Korea ( N. breviconcha ) 48 for 16S rRNA . The outgroup species used were Unio pictorum , Cuneopsis heudei , Cuneopsis rufescens , Cuneopsis pisciculus , and Schistodesmus lampreyanus for the CO1 dataset and Unio pictorum and Cuneopsis heudei for the 16S rRNA dataset.…”

“…The unionid mussels are known to play key roles in maintaining aquatic ecosystems such as nutrient circulation, water purification, and habitat supply 3 . Over the recent years, populations of unionid mussel species have rapidly been decreased due to global anthropogenic disturbances including desertification, water pollution, and river fragmentation 4 , 5 . A total of 247 unionid species are now identified from the IUCN Red list of Threatened species 6 , 7 .…”

“…In this study, the phylogenetic relationships and population genetic structures of the East Asian Nodularia species were examined with mitochondrial CO1 and 16S rRNA data newly obtained from 86 N. douglasiae and 83 N. breviconcha individuals inhabiting the freshwater systems on the Korean Peninsula. The present analysis covers most of the areas inhabited by the two species on the Korean Peninsula and is based on extensive sampling to accurately determine the distribution of genetic variation, which was not expected from the previous studies 4,10,12,20 . The obtained data here were applied to estimate and discuss the historical origin and distribution processes of Nodularia across East Asia by integrating with all previously known data.…”

Assessing Genomic Diversity, Connectivity, and Riverscape Genetics Hypotheses in the Endangered Rough Hornsnail,Pleurocera Foremani, Following Habitat Disruption

“…Similarly, Barnett et al (2020) recently established that within timeframes as short as 36 years after impoundment, crayfish experienced significant genetic fragmentation in the Bear Creek and Cahaba River drainages in Alabama and Mississippi. Outside of the southeastern United States, fragmentation has been shown to hinder gene flow and decrease genetic diversity of fish ( Blanchet et al 2010 ; Dehais et al 2010 ; Faulks et al 2011 ; Gouskov et al 2015 ; Sotola et al 2017 ; Yamamoto et al 2019 ) and mussels ( Liu et al 2019 ). More research is needed, however, to assess patterns in understudied groups like freshwater gastropods.…”

Effects of both climate change and human water demand on a highly threatened damselfly

“…Free-flowing rivers are characterized by a gradient in physicochemical conditions that govern a biotic gradient of vertebrates and invertebrates from upstream to downstream 11 . However, most rivers worldwide are disturbed by dams, which have consequences for hydrology 12 , sediment loads 13 , fish and invertebrate migration 14 , genetic diversity of populations 15 , and other ecological processes 16 . The combined effects of river damming and drought, which is regular in a hot climate 17 , might exacerbate the ecological impacts of climate change and may lead to the extinction of aquatic fauna 18 .…”