High-throughput based detection of eukaryotic pathogens for sea cucumber in Dalian costal area

Abstract

Sea cucumbers inhabit benthic environments and primarily feed on seabed sediments. Analyzing the community composition of eukaryotic species in their culture environment provides a scientific basis for assessing culture-related risks. In this study, we employed high-throughput sequencing (HTS) techniques to investigate potential pathogens associated with fungal and parasitic diseases affecting sea cucumbers in the Dalian coastal area. Concurrently, various environmental factors were measured seasonally to evaluate their potential impacts on the relative abundance of the identified pathogens. The results indicated that two fungal phyla, Ascomycota and Basidiomycota, associated with sea cucumber body vesicular syndrome (BVS), were present in considerable abundance in both the water and sediment of the national farm. Additionally, Acoela, known parasitic turbellarians of sea cucumbers, were also detected in significant numbers in the sediment, particularly during the summer months. The results of principal coordinate analysis (PCoA) revealed that the structure of eukaryotic communities in both water and sediment exhibited significant seasonal variation. Furthermore, temperature and total organic carbon (TOC) were found to have significant positive effects on the seasonal relative abundance of Acoela in the sediment. Conversely, pH appeared to negatively influence the relative abundance of the identified fungal phyla, while the eutrophication index (E) exhibited a positive effect. These findings demonstrate the feasibility of utilizing HTS techniques for detecting pathogenic eukaryotes in sea cucumber farms. We recommend incorporating high-throughput-based pathogenic monitoring into management strategies at sea cucumber farms to mitigate losses resulting from infectious disease outbreaks. For future research, it is essential to develop more efficient primers or primer mixes for detecting additional pathogenic threats and to enhance disease control measures in sea cucumber farms, particularly those focused on broodstock production.