Species diversity of drifting fish eggs in the Yangtze River using molecular identification

Abstract

The dam constructions greatly changed the hydrologic conditions in the Yangtze River, and then significantly affected the spawning activities of indigenous river fish. Monitoring the species composition of drifting eggs during spawning season is important for protection issues. In this study, we have sampled drifting fish eggs in nine locations from 2014 to 2016. Eggs were identified using the mitochondrial cyt b gene sequence. A total of 7,933 fish eggs were sequenced successfully and blasted into the NCBI database. Thirty-nine fish species were identified, and were assigned to four families and two orders. Approximately 64% of the species identified, and 67% of the eggs, were classified in the Family Cyprinidae. Abundance and Shannon–Wiener diversity index of species were higher in the main river than in tributaries of the river. However, tributaries may be important spawning grounds for some fish species. The Jaccard’s similarity index and river-way distances among sampled stations were negatively correlated suggesting the environment shapes species composition in the sampled spawning grounds. These results showed that mitochondrial DNA sequence is a powerful and effective tool for fish egg identification in Yangtze River and these data are useful for conservation efforts.

Formalin-Fixed Fish Larvae Could Be Effectively Identified by DNA Barcodes: A Case Study on Thousands of Specimens in South China Sea

“…The rate of successful identification in our study was similar to that in studies on fish larvae in the eastern Atlantic Ocean and Taiwanese waters (Ko et al, 2013;Ardura et al, 2016) but much lower than the rates obtained in many previous DNA barcode studies on fish larvae (Frantine-Silva et al, 2015;Hubert et al, 2015;Steinke et al, 2016;Liu et al, 2018), which may be mainly explained by the incompleteness of the DNA barcode reference libraries used for the SCS fishes. Despite the more than 3,300 fish species documented in the SCS, barcode sequences for fewer than 1,000 species have been published (Wang et al, 2009(Wang et al, , 2012Zhang and Hanner, 2012;Chang et al, 2017;Hou et al, 2018).…”

“…Because the fish larvae were fixed in formalin, their morphological features were better maintained than those of fish larvae preserved in ethanol. In past investigations with larval and/or planktonic delimitation based on molecular techniques, the samples were preserved in ethanol, which damaged their morphological characters (Frantine-Silva et al, 2015;Hubert et al, 2015;Ardura et al, 2016;Collet et al, 2018;Liu et al, 2018). Hence, our study is one of the first reports in which DNA-based species identification was applied to a large number of fish larvae fixed in formalin.…”

Comparing fish prey diversity for a critically endangered aquatic mammal in a reserve and the wild using eDNA metabarcoding

“…We detected greater species richness in spring versus summer samples in both regions and at most of the sampling sites (Table 2). May through July encompasses the breeding season of most fish species in the Yangtze River 64 and it is thus possible that detection probabilities were higher during our spring sampling simply because there were more eDNA sources for some species (e.g. gametes, fish fry) 23 .…”

DNA barcoding reveals the temporal community composition of drifting fish eggs in the lower Hongshui River, China

“…Fish eggs and larvae represent important sources of information about the early phases of fish development, providing valuable data about spawning locations, spawning times, recruitment success rates, and the reproductive intensities of multiple species (Baumgartner et al., 2004 ; Bialetzki et al., 2005 ; Cao et al., 2007 ). An accurate understanding of this information has important implications for the management of regional fish resources (Armsworth, 2002 ; Liu et al., 2018 ). Fish eggs provide more direct data concerning the abundance of spawning fish populations than larvae due to the reduced cumulative influence of egg transport and mortality (Richardson et al., 2009 ).…”