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Microcystins accumulate in aquatic organisms and can be transferred to higher trophic levels, eventually affecting vector animals and consumers. We examined three levels of an aquatic food chain (Microcystis aeruginosa, Daphnia magna and Macrobrachium rosenbergii) to identify the transfer efficiency and risk of microcystin on prawns. Samples were analysed using ultra performance liquid chromatography‐mass spectrometry (MS)/MS and microcystin‐LR (MC‐LR) distributions in prawn tissues were studied. The results showed that prawns accumulate MC‐LR both directly from M. aeruginosa and indirectly through D. magna which was pre‐exposed to M. aeruginosa. MC‐LR was detected in the gills, digestive tracts and hepatopancreas of the prawns 2 h after exposure. MC‐LR accumulated in prawns to 0.49 ± 0.04 μg g−1 dry weight in hepatopancreas within 24 h, while it was not detected in muscle samples, and rarely appeared in blood samples in such a short period. Although MC‐LR was not detected in muscle, the head including hepatopancreas of the prawns accumulated troublesome amounts of MC‐LR. These results demonstrate that microcystis blooms in prawn farming potentially pose a risk to human consumers, although prawns may be exposed to the bloom for a very short time, hence regular monitoring of blue green algae population is recommended.

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This study explored the pharmacokinetic characteristics of bronopol in grass carp (Ctenopharyngodon idella) under different temperatures. The concentrations of bronopol in the plasma and tissues (kidney, liver and muscle) of grass carp after soaking in bronopol (6.75 µg/ml) at 15 and 20°C were determined using liquid chromatography–mass spectrometry. The concentrations of bronopol in both plasma and tissue first increased and then decreased with soaking time at both tested temperatures. The peak bronopol concentrations at 15°C (plasma: 8.934 µg/ml; kidney: 9.23 µg/g; liver: 9.47 µg/g; and muscle: 7.98 µg/g) were slightly lower than those at 20°C (plasma: 9.654 µg/ml; kidney: 10.83 µg/g; liver: 13.40 µg/g; and muscle: 8.68 µg/g). In an analysis of pharmacokinetic parameters, the bronopol concentration–time profiles for plasma were best described by a two‐compartment, open pharmacokinetic model with first‐order absorption. The t1/2β for plasma at 15 and 20°C was 82.933 and 92.041 hr, respectively, indicating that the elimination of bronopol was faster at 15°C than at 20°C. In addition, AUC0‐t and AUC0‐∞ values of bronopol were 477.892 and 495.809 µg/L hr at 15°C and 495.809 and 589.859 µg/L hr at 20°C, indicating that the content of bronopol in the organism was higher at higher temperature.