Characterization of Indigenous and Introduced Toxic Phytoplankton in Antarctica

摘要OPP-9615831海洋浮游植物种类数以千计，但只有少数几种能产生强烈的毒素。这些物种出现在大规模的“赤潮”中，也就是使水变色的细胞大量繁殖的地方。更常见的是，这些生物的浓度很低，只有通过它们的毒素对水生生物和人类的影响才能引起人们的注意。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容易反复爆发。因此，在南极软体动物中发现了海洋藻毒素(SAXITOX)，这是令人震惊的。这一发现的意义是深远的，因为初级生产者和顶级捕食者之间的营养水平较低，而且已经证明，岩藻毒素有能力改变食物网络的结构和动态。Saxitoxins可以影响浮游动物、鱼苗、鲸鱼、江豚、海鸟和人类。一个令人担忧的问题是，可能是通过南美洲和南极半岛之间的船只交通，产生萨克毒素的藻类--可能是亚历山大藻属的甲藻--被引入南极水域。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水域之间确实存在短而频繁的运输路径。还有一种可能是，这种产生岩藻毒素的生物体是南极洲特有的，直到最近才被注意到。无论是哪种情况，对南极食物链的影响都是重大的。这项建议的目的是确定和描述南极洲麻黄毒素的可能来源(S)，以确定致病生物是本地物种还是引进物种，如果引入，则确定可能的来源和运输途径。

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.