Caihong Chen,Haiyan Wu,Guanchao Zheng,Limin Lu,Zhijun Tan
Prorocentrum lima is a widely distributed and major source of diarrhetic shellfish toxins (DSTs); the ecological impact of diol-estered DSTs (eDSTs) compounds on benthic systems is still inadequate. In this study, the acute toxicity of eDSTs was evaluated in Caenorhabditis elegans , and their accumulation capacity and toxic effects were examined in Mytilus galloprovincialis for an ecological risk assessment. The results indicated that larvae 1 (L1) was more sensitive than larvae 4 (L4) of C. elegans , and the eDSTs in P. lima extract lysate were more toxic than the okadaic acid (OA) standard solution. The lowest LC 50 values were 0.293 and 0.469 μg/mL for L1 and L4, respectively. The growth, productivity, and intestinal permeability of C. elegans were impaired, and the effect of P. lima extract lysate on C. elegans was greater than that of the OA standard solution. The total toxin concentration in the digestive gland of mussels reached 3230 μg/kg, with esterified DSTs accounting for 76.7–97.1% of total toxins and inducing marked oxidative stress. Diol-estered DSTs exert direct toxic effects, including oxidative damage and growth inhibition, while exhibiting a high accumulation potential. This study revealed the toxicity of eDSTs, necessitating a focused investigation to comprehensively assess their toxicological impact and ecological risks.
Antibiotics have been widely detected in the ocean and have various impacts on the environment, while knowledge of their chronic influence on phytoplankton , especially red tide algae, is still limited. Dinoflagellates and green algae are common phytoplankton in marine ecosystems . The former is the main red tide algae, and the latter is an important primary producer. We investigated the long-term responses of two representative algae, Prorocentrum lima and Chlorella sp., to two common antibiotics (sulfamethoxazole (SMX) and norfloxacin (NFX)) at environmentally relevant levels (10 and 100 ng/L) during simulated natural conditions. The cell density and activities of three antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD)) were analyzed. The results showed that the influence of each antibiotic on Chlorella sp. was not significant ( p > 0.05) during the first 10 days, but the influence of the antibiotics later began to show significant inhibition ( p < 0.05) compared with the control group, especially during mixed exposure. P. lima was not inhibited, but its cell density increased. SMX had a superior stimulation effect on P. lima . The three enzymes activities of P. lima increased, and the antioxidant mechanism was not seriously impacted. However, for Chlorella sp., the activity of SOD increased while the activities of CAT and POD decreased, suggesting that this algae’s antioxidant system was unbalanced due to oxidative stress . Based on our results, the growth of P. lima was different from green algae Chlorella sp. as well as other inhibited marine algae (such as diatom, golden algae) studied in previous studies. Therefore, as a typical pollutant in the ocean, antibiotics may play a positive role in the bloom of dinoflagellate red tides.
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