通过食用受污染的猎物或直接暴露于有毒细胞，藻毒素参与了海洋生物的死亡和/或疾病。本研究调查了受威胁的绿海龟（Chelonia mydas）消化道内容物中潜在有毒微藻细胞的存在。此外，通过LC-MS/MS分析了巴西南部在2015年冬至2016年秋期间搁浅的选定动物（n = 39个个体）的组织样本（肝脏，胃和/或肠道）中的亲脂性毒素。在绿海龟的消化道内容物中，发现了13种潜在的有毒微藻（包括硅藻、浮游生物和底栖生物），其中包括7种甲藻、6种蓝藻和1种硅藻。其中，属于锐顶槽藻复合物的甲藻是最常见的（36%），并且数量最多（2015年春季达到平均最大浓度566个细胞克-1）。此外，23%的受检测海龟在清洗的消化组织中有可检测到的致泻贝毒烯酸（okadaic acid，OA）水平。其中有7只个体在肠道中积累了OA（最大为24.1 ng克-1），而两只在胃中积累了OA（最大为7.4 ng克-1）。组织中的毒素水平与绿海龟消化道内容物中产生OA的锐顶槽藻和尖针内盘红藻（Prorocentrum lima）的细胞丰度直接且显著相关（r = 0.70，p < 0.025）。尽管OA浓度相对较低，但可能的慢性暴露可能会恶化受暴露海龟的一般健康状况，增加疾病风险。致泻贝毒烯酸被认为是一种肿瘤促进化合物和纤维肉瘤病（一种在这一地理区域中常见的疾病，多发于绿海龟幼体）发生的环境共因子。尽管如此，在六只被检测的绿海龟中，只有一只在消化组织中含有OA，同时又在本研究中出现了纤维肉瘤病。然而，海龟是海洋健康的景观。监测藻毒素的积累及其对这些生物的负面影响有助于保护生物多样性和海洋栖息地。版权所有 © 2023 Elsevier B.V. 保留所有权利。

Algal toxins are involved in the mortality and/or illness of marine organisms via consumption of contaminated prey, or upon direct exposure to toxic cells. In this study, the presence of potentially toxic microalgal cells was investigated within the digestive tract contents of a threatened species of green turtle (Chelonia mydas). Additionally, lipophilic toxins were determined by LC-MS/MS in tissue samples (liver, stomach and/or intestine) of selected animals (n = 39 individuals) found dead-stranded in southern Brazil, from winter/2015 to autumn/2016. Thirteen potentially toxic species of microalgae (both benthic and planktonic), including seven dinoflagellates, six cyanobacteria and one diatom, were found in the digestive tract contents of green turtles. Among them, dinoflagellates belonging to the Dinophysis acuminata species complex were the most frequent (36%) and abundant (maximum average abundance of 566 cells g-1 in spring/2015). Moreover, 23% of the examined sea turtles exhibited detectable levels of the diarrhetic shellfish toxin okadaic acid (OA) in washed digestive tissues. Seven individuals accumulated OA in their intestines (max. 24.1 ng g-1) and two in the stomachs (max. 7.4 ng g-1). Toxin levels in the tissues were directly and significantly (r = 0.70, p < 0.025) associated with the cell abundance of OA-producing D. acuminata and Prorocentrum lima species complexes within the digestive contents of green turtles. Although OA concentrations were relatively low, possible chronic exposure might deteriorate general health conditions of exposed sea turtles, increasing the risk for diseases. Okadaic acid has been regarded as a tumor-promoting compound and an environmental co-factor in the incidence of fibropapillomatosis, a frequent disease in juvenile green turtles inhabiting this geographic region. Even though, only one green turtle containing OA in the digestive tissues (out of six examined) also presented fibropapillomatosis in this study. Notwithstanding, sea turtles are sentinels of ocean health. Monitoring the accumulation of algal toxins and their negative effects on these organisms contributes to conserving biodiversity and marine habitats.Copyright © 2023 Elsevier B.V. All rights reserved.