College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China; Key Laboratory of Marine Environment and Ecology, Ocean University of China, Ministry of Education, Qingdao 266100, China.
College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China.
Harmful Algae. 2020 Mar;93:101797. doi: 10.1016/j.hal.2020.101797.
In recent years, marine bivalves cultured in the natural environment have been confirmed to accumulate diarrhetic shellfish toxins (DSTs) from the aqueous phase. To investigate the effects of varying seston concentrations on DST accumulation, mussels (Mytilus galloprovincialis) were exposed to comparable concentrations of okadaic acid (OA) and dinophysistoxin-1 (DTX1) in 0.45-μm filtered seawater spiked with varying concentrations of ambient suspended particles at 0, 10, 30, 60, 90, and 120 mg L, for 96 h. Effects of seston additions on the mussels' feeding on nontoxic microalgae, Isochrysis galbana, the stability of dissolved toxins and the anatomical compartmentalization of toxins were also assessed. Results showed that mussels more readily accumulated OA than DTX1 from the aqueous phase. Three potential mechanisms of the effects of seston on toxin accumulation were identified. First, seston at low concentrations (10 mg L) adsorbed toxins and thus promoted toxin accumulation. Second, seston enhanced the degradation of aqueous OA and DTX1, and possibly reduced the adsorption by digestive gland (DG) cells through simple diffusion due to competitive adsorption. Third, the clearance rate of mussels was significantly reduced at high seston concentrations (120 mg L). The esterification of DSTs was maximized in DG tissue, although a high percentage (52%) of DSTs was distributed in non-visceral tissues of mussels exposed to aqueous toxins. This study suggests that the risk of benthic DST-producing microalgae to marine cultured shellfish should be taken into consideration, even in the absence of a bloom of toxic microalgae in the water column.
近年来，已证实天然环境中养殖的海洋双壳贝类会从水相中蓄积腹泻性贝类毒素（DSPs）。为了研究不同悬浮物浓度对 DSP 蓄积的影响，将贻贝（Mytilus galloprovincialis）暴露于经 0.45μm 过滤海水配制的、浓度相当的冈田酸（OA）和鳍藻毒素-1（DTX1）中，同时向其中添加不同浓度的环境悬浮颗粒物，浓度分别为 0、10、30、60、90 和 120mg/L，共 96h。还评估了悬浮物添加对贻贝摄食无毒微藻（Isochrysis galbana）、溶解态毒素稳定性以及毒素解剖学区室化的影响。结果表明，贻贝从水相中更易蓄积 OA 而非 DTX1。确定了悬浮物对毒素蓄积影响的 3 种潜在机制。首先，低浓度（10mg/L）的悬浮物会吸附毒素，从而促进毒素蓄积。其次，悬浮物增强了水相 OA 和 DTX1 的降解，并可能通过简单扩散因竞争吸附而降低了 DG 细胞的吸附。第三，在高悬浮物浓度（120mg/L）下，贻贝的清除率显著降低。尽管暴露于水相毒素的贻贝 52%的 DSPs 分布于非内脏组织中，但 DG 组织中 DSPs 的酯化作用达到最大化。该研究表明，即使水柱中没有有毒微藻的爆发，也应考虑底栖产 DSP 微藻对海洋养殖贝类的风险。
