DNA metabarcoding approach to the determination of the diet spectrum of the common  sunbleak Leucaspius delineatus (Heckel, 1843)

The common sunbleak (Leucaspius delineatus) is an invasive fish found in Siberian water bodies, the trophic interactions and impact on local ecosystems of which remain poorly understood. Traditional diet analyses are limited by the mechanical damage to the prey. For the present study, therefore, we employed DNA metabarcoding of the cytochrome c oxidase I (cox1) gene to analyze the digestive tract contents of the common sunbleak obtained from Irkutsk Reservoir. Our analysis revealed 53 operational taxonomic units (OTUs), with sequences of amphibiotic insects (58.66%) and fish (34.10%) being the most prevalent. A significant proportion of the fish DNA, including sequences from Baikal omul, can be attributed to environmental DNA (eDNA) derived from mucus, scales, or feces that were ingested directly or indirectly with detritus. The common sunbleak’s summer diet is based primarily on amphibiotic insects, although molecular data are confounded by the coingestion of eDNA. The present study assesses the ecological impact of the common sunbleak, and underscores the critical importance of differentiating between active predation and eDNA in dietary metabarcoding studies.