Centre for Ocean Life, National Institute for Aquatic Resources, Technical University of Denmark, 2920 Charlottenlund, Denmark; Key and Open Laboratory of Marine and Estuary Fisheries, Ministry of Agriculture of China, East China Sea Fisheries Research Institute, Chinese Academy of Fisheries Sciences, 200090 Shanghai, China.
Marine Biological Section, University of Copenhagen, 3000 Helsingør, Denmark.
Harmful Algae. 2017 Feb;62:1-9. doi: 10.1016/j.hal.2016.11.020. Epub 2016 Dec 15.
Zooplankton responses to toxic algae are highly variable, even towards taxonomically closely related species or different strains of the same species. Here, the individual level feeding behavior of a copepod, Temora longicornis, was examined which offered 4 similarly sized strains of toxic dinoflagellate Alexandrium spp. and a non-toxic control strain of the dinoflagellate Protoceratium reticulatum. The strains varied in their cellular toxin concentration and composition and in lytic activity. High-speed video observations revealed four distinctly different strain-specific feeding responses of the copepod during 4h incubations: (i) the 'normal' feeding behavior, in which the feeding appendages were beating almost constantly to produce a feeding current and most (90%) of the captured algae were ingested; (ii) the beating activity of the feeding appendages was reduced by ca. 80% during the initial 60min of exposure, after which very few algae were captured and ingested; (iii) capture and ingestion rates remained high, but ingested cells were regurgitated; and (iv) the copepod continued beating its appendages and captured cells at a high rate, but after 60min, most captured cells were rejected. The various prey aversion responses observed may have very different implications to the prey and their ability to form blooms: consumed but regurgitated cells are dead, captured but rejected cells survive and may give the prey a competitive advantage, while reduced feeding activity of the grazer may be equally beneficial to the prey and its competitors. These behaviors were not related to lytic activity or overall paralytic shellfish toxins (PSTs) content and composition and suggest that other cues are responsible for the responses.
浮游动物对有毒藻类的反应变化多样，即使是对分类上密切相关的物种或同一物种的不同菌株也是如此。在这里，研究了一种桡足类动物（Temora longicornis）的个体水平摄食行为，该动物提供了 4 种大小相似的有毒甲藻（Alexandrium spp.）菌株和一种无毒的甲藻（Protoceratium reticulatum）对照菌株。这些菌株在细胞毒素浓度和组成以及裂解活性方面存在差异。高速视频观察揭示了桡足类动物在 4 小时孵育期间对 4 种不同菌株表现出的四种明显不同的特异性摄食反应：（i）“正常”摄食行为，在此期间，摄食附肢几乎不停地拍打以产生摄食流，并且大部分（90%）捕获的藻类被摄入；（ii）在暴露的最初 60 分钟内，摄食附肢的拍打活动减少了约 80%，此后很少有藻类被捕获和摄入；（iii）捕获和摄入率仍然很高，但摄入的细胞被吐出；（iv）桡足类动物继续以高速度拍打其附肢并捕获细胞，但在 60 分钟后，大多数捕获的细胞被拒绝。观察到的各种回避反应可能对猎物及其形成水华的能力有非常不同的影响：被消耗但被吐出的细胞是死亡的，被捕获但被拒绝的细胞存活下来，并可能使猎物具有竞争优势，而捕食者的摄食活动减少可能对猎物及其竞争者同样有利。这些行为与裂解活性或总麻痹性贝类毒素（PSTs）含量和组成无关，表明其他线索是导致这些反应的原因。
