Characterization of Indigenous and Introduced Toxic Phytoplankton in Antarctica

摘要 粤ICP备15015831号-1 海洋浮游植物有数千种，但只有少数几种能产生强效毒素。 这些物种存在于大量的“赤潮”或使水变色的细胞水华中。 更常见的是，这些生物的浓度很低，只有通过其毒素对水生生物和人类的影响才能注意到。 近年来，有毒浮游植物问题的性质发生了很大变化，因为许多以前未受影响的地区现在经常爆发。 因此，令人震惊的是，在南极软体动物中发现了海藻毒素（石房蛤毒素）。 鉴于初级生产者和顶级捕食者之间的营养水平低，以及石房蛤毒素改变食物网结构和动态的能力，这一发现的影响是深远的。 石房蛤毒素可影响浮游动物、鱼苗、鲸鱼、鼠海豚、海鸟和人类。 令人担忧的是，可能是南美洲和南极半岛之间的船只运输将产石房蛤毒素的石房蛤（可能是Alexandrum属的腰鞭毛虫）引入南极沃茨。 这种物种扩散机制与世界其他地区突然出现的有毒藻类有关。 南极与智利南部和阿根廷的高毒性沃茨之间确实存在短而频繁的迁移路径。 也有可能这种产生石房蛤毒素的生物是南极洲的土著，只是最近才被注意到。 无论哪种情况，对南极食物网的影响都是重大的。 本提案的目的是查明南极洲石房蛤毒素的可能来源并确定其特性，以确定致病生物是本地物种还是引进物种，如果是引进物种，则查明可能的来源和迁移途径。

Abstract OPP-9615831 There are thousands of species of marine phytoplankton, but only a few produce potent toxins. These species are found in the massive `red tides" or blooms of cells that discolor the water. More commonly, the organisms are present at low concentrations and are noticed only by the effects their toxins have on aquatic organisms and humans. The nature of the toxic phytoplankton problem has changed considerably in recent years as many areas that were previously unaffected are now subject to recurrent outbreaks. Therefore, it is alarming that marine algal toxins (saxitoxins) have been found in Antarctic molluscs. The implications of this discovery are profound given the low number of trophic levels between primary producers and top predators and the proven ability of the saxitoxins to alter the food web structure and dynamics. Saxitoxins can affect zooplankton, fish larvae, whales, porpoises, seabirds, and humans. A concern is that the saxitoxin-producing alga, presumably the dinoflagellates in the genus Alexandrium, has been introduced to Antarctic waters, possibly by vessel traffic between South America and the Antarctic Peninsula. This mechanism of species dispersal has been implicated in the sudden appearance of toxic algae in other areas of the world. Short and frequent transport pathways do exist between Antarctic and the high-toxicity waters of southern Chile and Argentina. It is also possible that the saxitoxins-producing organism is indigenous to Antarctica and was only recently noticed. In either case, the implications to the Antarctic food web are significant. The objectives of this proposal are to identify and characterize the possible source(s) of saxitoxins in Antarctica to determine whether the causative organisms are indigenous or introduced species, and if introduced, to identify the probable origin and transport pathway.