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

Delimiting ichthyoplankton is fundamental work for monitoring the recruitment process and identifying spawning nursing grounds of fishes. Nevertheless, it extremely difficult to identify fish during early stages at species level based on morphological characters because paucity diagnostic features. In this study, we investigated larval community through large-scale ecosystemic sampling in South China Sea (SCS) 2013 2017 using DNA barcodes. To maintain morphologies larvae, preserved larvae formalin developed a technique recover their DNA. Among 3,500 chosen successfully extracted from 2,787 samples obtained 1,006 high-quality sequences. Blast searches showed that 408 (i.e., 40.5%) could be unambiguously identified species, 413 41.1%) were ambiguously delimitation, 185 18.4%) low match similarity with target A total 101 identified, among which 38 33 corresponded demersal reef-associated whereas remaining 30 benthopelagic, pelagic-oceanic, bathypelagic, pelagic-neritic species. High-quality photographs diagnosed intact thus provided reference characters. Our study highlighted possibility recovering amplifying formalin-fixed new insight into SCS.