Assessment of Sediment Quality and Benthic Community Structure of the Quanzhou Bay, Fujian Province, China

The Chinese government is vigorously advancing the initiative of constructing ‘Beautiful Bay’ as part of its broader environmental governance strategy to enhance marine ecological protection and achieve sustainable coastal development. As a fundamental unit and operational carrier for marine ecological and environmental protection efforts, bays play a crucial role in the effective implementation of conservation strategies. The precise management and governance of a bay’s ecological environment are of utmost significance, directly influencing the success of marine conservation initiatives and the overall health of coastal ecosystems. This study focuses on Quanzhou Bay as the primary case study site. Sediment quality and benthic community structure were assessed in 2020 at 12 strategically located sampling stations. A comprehensive evaluation of surface sediment characteristics and benthic organisms was conducted using both the single-factor index method and the integrated comprehensive evaluation method. These methodologies facilitated the identification of sediment contamination and enabled a scientific assessment of potential ecological risks using principal component analysis. The findings demonstrated that, with the exception of elevated levels of petroleum hydrocarbons, zinc, cadmium, and lead at stations S3 and S6—which exceeded the first-category criteria outlined in the Marine Sediment Quality manual—all other sediment parameters were in accordance with the first-category standards. Moreover, the comprehensive pollution index for heavy metals across all stations was found to be less than 1, indicating a generally clean sediment status. A total of 88 benthic species were identified across the 12 sampling stations. These species were categorized into four major classes: polychaetes, crustaceans, mollusks, and echinoderms. Of these, polychaetes were the most abundant, with 56 species recorded. The Index of Relative Importance identified Chaetozone setosa and Cossurella dimorpha as the dominant species. The study revealed that while most sediments in Quanzhou Bay were uncontaminated, elevated levels of zinc, cadmium, lead, and petroleum hydrocarbons were detected at stations S3 and S6, exceeding established environmental standards. The cause of these anomalies was attributed to industrial discharges and anthropogenic activities. Consequently, the implementation of targeted measures to prevent, control, treat, and remediate these localized issues is recommended.