Current Status of Seaweed Feeding in Mesocentrotus nudus Identified by DNA Barcode

Abstract

This study investigated the feeding sources of sea urchins, specifically focusing on their algivorous habits, to demonstrate the impact of these algivores on barren ground formation. It was part of a research plan to verify factors influencing algal barren grounds. Using metabarcoding, an intestinal contents mixture (digestive organs, food, and feces) was sampled and pretreated for genetic analysis. Barcode markers for seaweed species analysis were selected, and experimental conditions were established. Seaweed feeding habits were examined in 180 samples of Mesocentrotus nudus from the Uljin coastal area (Bongsu Port, Osan Port, and Gusan Port). Genomic DNA from the intestinal contents mixture was isolated and purified by modifying the lysis method for plant tissues and fecal samples. DNA barcodes for marine macrophytes were prepared using the rbcL, COI, and ITS gene regions. Analysis revealed that M. nudus consumed significant amounts of seaweed, with variations in species (red, green, and brown algae) depending on sampling time and location. This study provides a foundation for applying metabarcoding to analyze intestinal contents in seaweed-eating animals. Future studies will identify and report the specific seaweed feeding sources of M. nudus at the species level.