Laboratório Marítimo da Guia, Centro de Oceanografia, Faculdade de Ciências da Universidade de Lisboa, Av. Nossa Senhora do Cabo, 939, 2750-374 Cascais, Portugal; IPMA - Instituto Português do Mar e da Atmosfera, Avenida de Brasília, 1449-006 Lisboa, Portugal.
Laboratório Marítimo da Guia, Centro de Oceanografia, Faculdade de Ciências da Universidade de Lisboa, Av. Nossa Senhora do Cabo, 939, 2750-374 Cascais, Portugal.
Aquat Toxicol. 2014 Jan;146:205-11. doi: 10.1016/j.aquatox.2013.11.011. Epub 2013 Nov 23.
Marine phycotoxins derived from harmful algal blooms are known to be associated with mass mortalities in the higher trophic levels of marine food webs. Bivalve mollusks and planktivorous fish are the most studied vectors of marine phycotoxins. However, field surveys recently showed that cephalopod mollusks also constitute potential vectors of toxins. Thus, here we determine, for the first time, the time course of accumulation and depuration of paralytic shellfish toxins (PSTs) in the common octopus (Octopus vulgaris). Concomitantly, the underlying kinetics of toxin transfer between tissue compartments was also calculated. Naturally contaminated clams were used to orally expose the octopus to PSTs during 6 days. Afterwards, octopus specimens were fed with non-contaminated shellfish during 10 days of depuration period. Toxins reached the highest concentrations in the digestive gland surpassing the levels in the kidney by three orders of magnitude. PSTs were not detected in any other tissue analyzed. Net accumulation efficiencies of 42% for GTX5, 36% for dcSTX and 23% for C1+2 were calculated for the digestive gland. These compounds were the most abundant toxins in both digestive gland and the contaminated shellfish diet. The small differences in relative abundance of each toxin observed between the prey and the cephalopod predator indicates low conversion rates of these toxins. The depuration period was better described using an exponential decay model comprising a single compartment - the entire viscera. It is worth noting that since octopuses' excretion and depuration rates are low, the digestive gland is able to accumulate very high toxin concentrations for long periods of time. Therefore, the present study clearly shows that O. vulgaris is a high-potential vector of PSTs during and even after the occurrence of these toxic algal blooms.
海洋藻类毒素与海洋食物网中较高营养级的大规模死亡有关，这些毒素来自有害藻类大量繁殖。双壳贝类和浮游鱼类是研究海洋藻类毒素的最主要载体。然而，最近的实地调查显示，头足类软体动物也可能是毒素的潜在载体。因此，我们首次确定了麻痹性贝类毒素（PSTs）在普通章鱼（Octopus vulgaris）体内的积累和消除的时间过程。同时，还计算了毒素在组织隔间之间转移的动力学。利用自然污染的贻贝，通过口服暴露章鱼 6 天，使章鱼接触 PSTs。之后，在 10 天的消除期内，章鱼用非污染的贝类喂养。毒素在消化腺中达到最高浓度，超过肾脏中浓度三个数量级。在任何其他分析的组织中都未检测到 PSTs。计算得出，对于 GTX5，其净积累效率为 42%，dcSTX 为 36%，C1+2 为 23%，用于消化腺。这些化合物是消化腺和污染贝类饮食中最丰富的毒素。在猎物和头足类捕食者之间观察到的每种毒素的相对丰度的微小差异表明这些毒素的转化率较低。使用包含单个隔室-整个内脏的指数衰减模型可以更好地描述消除期。值得注意的是，由于章鱼的排泄和消除速度较慢，消化腺能够在很长一段时间内积累非常高的毒素浓度。因此，本研究清楚地表明，在这些有毒藻类大量繁殖期间甚至之后，O. vulgaris 是 PSTs 的高潜在载体。
