Abstract:

Aims: Benthic organisms are a crucial part of marine ecosystems, playing an essential role in material cycling and energy flow. Gastropods, particularly through their predation and scavenging activities, help maintain the stability of benthic ecosystems. Understanding the dietary habits of gastropods is key to understanding their ecological role. Neptunea cumingii, a gastropod of significant ecological and economic importance in northern China, has not been sufficiently studied in terms of its diet and ecological role. Therefore, it is important to investigate the dietary composition of N. cumingii in natural conditions and to further understand its regulatory role in northern China’s benthic ecosystems.

Methods: In this study, four wild N. cumingii stomach samples were collected, and the stomach contents were analyzed using DNA barcoding techniques targeting the 18S rDNA V4 and V9 hypervariable regions to identify eukaryotic organisms.

Results: A total of 265,161 high-quality reads were obtained from the 18S rDNA V4 region across four samples, representing 93.16% of the original reads, and 141 operational taxonomic units (OTUs) were obtained by clustering. From the 18S rDNA V9 region, 221,998 high-quality reads were obtained, accounting for 86.54% of the original reads, and 490 OTUs were obtained. The 18S rDNA V4 region produced higher-quality sequences, but fewer annotated species compared to the V9 region. In total, 17 phyla were identified across all OTUs, including 10 from the animal kingdom, 5 from the fungal kingdom, 1 from the plant kingdom, and the SAR (Stramenopiles, Alveolates, and Rhizaria). The most abundant taxa in both the V4 and V9 analyses were Gastropoda, Actinopterygii, Trematoda, and Chromadorea. At the OTU level, only 5.67% and 8.08% of OTUs were detected across three or more samples, classified into the phyla Mollusca, Vertebrata, Ascomycota, and SAR. Overall, the analysis of the 18S rDNA V4 and V9 hypervariable regions revealed a diverse array of eukaryotic organisms, including animals (annelids, arthropods, mollusks), fungi, plants, and protists, with gastropods, fishes, trematodes, and fungi being the most abundant. A small percentage of OTUs were detected in multiple samples, indicating the variability of the diet.

Conclusions: The findings suggest that N. cumingii is an opportunistic feeder, obtaining energy from animal carcasses, sediments, and debris. It exhibits both herbivorous and predatory behaviors, which may help control fouling organisms. Its dietary composition is influenced by the local microenvironment, underscoring the species’ potential for use in bait domestication. This study provides insights into the role of N. cumingii in marine ecosystems and its nutritional needs for aquaculture.

Key words: Neptunea cumingii, DNA metabarcoding, 18S rDNA, stomach contents, dietary analysis