An Assessment of Seasonal Differences in Fish Populations in Laizhou Bay Using Environmental DNA and Conventional Resource Survey Techniques

Abstract

In recent years, environmental DNA (eDNA) technology has gradually improved, and it has been increasingly used to monitor marine fish. The decline and seasonal fluctuations of fish resources in Laizhou Bay, Bohai were studied using eDNA technology and compared with the results of conventional fish resource survey methods. In November 2020 (autumn), March 2021 (spring), and July 2021 (summer), 12 samples were collected each quarter in Laizhou Bay and adjacent waters for a total of 36 eDNA samples, and 47 fish species were identified. During the same trip, ground cages, gillnets, and trawls were used during two seasons. Fishery resource surveys were conducted at 12 sites from November 2020 (autumn) to March 2021 (spring), and in total 11 fish species were found. Our study found that fishery resources in Laizhou Bay significantly fluctuated with seasonal changes. Additionally, compared with traditional surveys, eDNA information included the same results, but also included fish that could not be collected because of the technical limitations of traditional surveys. Therefore, this study provides more accurate seasonal information for fish in Laizhou Bay, which is of great significance for the long-term management and conservation of coastal biodiversity.

Exploring Seasonal Variations in Fish Communities: A Study of the Yellow River Estuary and Its Adjacent Waters Using eDNA and Trawl Surveys

“…Consistent with previous research, the surface and bottom communities had a lower diversity in spring, whereas a higher diversity was observed in summer [37]. Biological diversity is closely related to the environment, especially in the estuary ecosystem [38].…”

“…In our study, temperate, subtropical, and tropical species accounted for 36%, 33%, and 31%, respectively, within the entire study area. In Laizhou Bay, the number of species preferring warm water was highest in all the seasons [37]. Thus, from the spring to the summer, as the water temperature rises, the diversity of fish species gradually increases.…”

“…Thus, from the spring to the summer, as the water temperature rises, the diversity of fish species gradually increases. Moreover, the climatic conditions and temperatures in the Yellow River Estuary and its surrounding waters are more favorable for biological growth in the summer than in other seasons, with a greater abundance of natural bait organisms [37]. Additionally, some researchers suggested that the differences in diversity indices among the different seasons were attributed to the seasonal spawning, feeding, and overwintering migrations of fish species [39,40].…”

“…In addition, comparing the results from the two seasons, we found that the number (41) of species detected exclusively by eDNA was lower than the number (51) detected by eDNA and trawl surveys. The utilization of eDNA as a complementary tool to conventional approaches can reveal a broader taxonomic diversity and provide a more comprehensive perspective on species composition in aquatic ecosystems [37,38].…”

eDNA Biomonitoring of Macroinvertebrate Communities for the Bioassessment of a River’s Ecological Status

“…We found that among the taxa detected by the eDNA technology across different orders, there were obvious differences from the historical records (Figure 3). Specifically, the number of Diptera, Neuroptera and Lepidoptera detected by the eDNA technology was higher than in the historical records, which may be because the eDNA technology performs a species annotation at the molecular level and could monitor some species that were not easily detected using conventional techniques [48]. However, it was also slightly insufficient in the monitoring of other macroinvertebrates, such as Megaloptera, Hemiptera and Trichoptera.…”