The pervasive occurrence of antibiotics in marine environments has aroused increasing ecological and human health concerns, especially in estuarine and coastal zones. However, current water quality criterias (WQCs) are primarily derived from freshwater datasets, which may not accurately capture marine species sensitivity. In this study, toxicity data for ten antibiotics were compiled from the literature, with oxytetracycline (OTC) and tetracycline (TC) selected as representative compounds. Acute and chronic toxicity assays were performed on representative marine organisms, including Vibrio fischeri , Chlorella vulgaris , and Moina mongolica , to complement the existing dataset. Species sensitivity distribution (SSD) models were established to derive marine-specific predicted no-effect concentrations (PNECs). The effects of species composition (marine vs. freshwater), non-native exclusion, and microbial inclusion on WQCs were assessed by comparing SSD models. The results indicated that marine species exhibited lower short-term but higher long-term sensitivity to antibiotics compared with freshwater species. Non-native exclusion and microbial inclusion both yielded more conservative PNECs, highlighting their key roles in risk assessment. Based on chronic WQCs of OTC and TC (1.71 × 10 -4 and 4.81 × 10 -4 mg/L, respectively), risk assessment was conducted for four Chinese coastal regions: Bohai Bay, Laizhou Bay, Yellow River Estuary, and Pearl River Estuary. Limited available data revealed overall low and declining antibiotic risks, with a spatial pattern of "north high, south low", although some sites still exhibited medium to high risks. This study emphasizes the importance of incorporating native marine-specific and microbial toxicity data into future WQCs development, supporting refined management of antibiotic pollution in coastal ecosystems. • A freshwater-marine toxicity dataset of antibiotics for SSD modeling is compiled. • Acute PNECs in marine are higher than those in freshwater, but lower for chronic. • Excluding non-native species and incorporating microbial both yield lower PNECs. • The chronic WQCs for OTC and TC are 0.171 and 0.481 μg/L, respectively. • The limited data show a downward risk trend with a “north-high, south-low” pattern.
Zhang et al. (Fri,) studied this question.