Unraveling the Drifting Larval Fish Community in a Large Spawning Ground in the Middle Pearl River Using DNA Barcoding

Simple Summary DNA barcoding identified 28 species from larvae collected from the Dongta spawning ground. Six invasive species were identified in the larval pool, implying that these species had successfully colonized the middle Pearl River. Several migratory species common in the lower Pearl River were rare or absent in the Dongta spawning ground, suggesting that adverse effects of dam construction posed on these migratory species. Our study provided important reference data for fishery management and conservation in the Pearl River. Resolving the species composition of a larval pool in a spawning ground can provide novel insights into regional fish stocks and can support the development of effective monitoring and conservation policies. However, it is challenging to identify fish larvae to species due to their high diversity and dramatic phenotypic changes over development. In this study, we collected fish larvae in the Dongta spawning ground (Guiping City, Guangxi Province, China) in the middle reaches of the Pearl River between May and August 2018. We used a DNA barcoding approach to determine the species composition of the larval pool. A total of 905 larvae were chosen for molecular identification, of which 750 yielded high-quality barcoding sequences. Of these, 597 (approximate to 79.6%), 151 (approximate to 20.1%)/and 2 (approximate to 0.3%) were assigned to 28 species, 8 genera, and 1 subfamily using the Barcode of Life Data System and GenBank nucleotide databases, respectively. Among the 28 identified species, 21 were cyprinids. Two species (Mugilogobius myxodermus and Pseudolaubuca engraulis) that were present only infrequently in previous adult surveys were abundant in the larval pool. Six invasive species were identified in the larval pool, implying that these species had successfully colonized the studied river section. Several migratory species common in the lower Pearl River were rare or absent in the investigated region, suggesting that dam construction in the Pearl River has had adverse effects on these migratory species. In summary, our study confirmed the applicability of DNA barcoding to studies of fish larval ecology and provided important reference data for fishery management and conservation in the Pearl River.