The mud flat anemone-cockle association: mutualism in the intertidal zone?
The mud flat anemone-cockle association: mutualism in the intertidal zone?
复制标题
泥滩海葵-鸟蛤协会：潮间带的互利共生？
作者：
K. Mouritsen;R. Poulin
潮间带鸟蛤 Austrovenus stutchburyi 与泥滩海葵 Anthopleura aureoradiata 存在共生关系，后者使用埋藏鸟蛤的壳作为唯一可用的附着基质。鸟蛤也是有害的幼虫吸虫（Curtuteria australis）的宿主，它通过过滤流侵入双壳类，在这里我们证明海葵显着降低了鸟蛤在田间积累寄生虫的速度。沿着潮汐梯度，在海葵最丰富的地方，鸟蛤的相对寄生虫负荷最低，每平方米沉积物表面海葵占据的面积解释了感染强度空间变化的30%。在较小的空间尺度上，在相同潮汐高度下，有海葵斑块的鸟蛤中的寄生虫负荷明显低于没有海葵的斑块中的寄生虫负荷（34%）。一项控制海葵密度的现场实验表明，随着海葵密度的增加，鸟蛤中寄生虫积累的速度会降低，并且在海葵存在的情况下，感染强度和鸟蛤大小之间普遍存在的正相关关系往往会消失。结果表明，海葵与鸟蛤的共生是一种非专性的互惠关系，其中前者提供了合适的附着基质，而后者获得了针对寄生虫感染的保护。
The intertidal cockle Austrovenus stutchburyi exists in a symbiotic relationship with the mud flat anemone Anthopleura aureoradiata, the latter using the shell of buried cockles as the only available hard substrate for attachment. The cockles are also host to a detrimental larval trematode Curtuteria australis that invades the bivalves through the filtration current, and here we demonstrate that the anemones significantly depress the rate by which cockles accumulate parasites in the field. Along the tidal gradient, the relative parasite load of cockles was lowest where anemones were most abundant, and the area occupied by anemones per square meter sediment surface explained 30% of the spatial variation in infection intensity. At a smaller spatial scale, parasite loads were significantly lower (34%) in cockles from patches with than without anemones at the same tidal height. A field experiment manipulating the density of anemones showed that the rate of parasite accumulation in cockles decreased with increasing anemone density, and that the generally positive relationship between infection intensity and cockle size tended to disappear in the presence of anemones. The results suggest that the anemone-cockle symbiosis is a non-obligate mutualistic relationship in which the former is provided with a suitable substrate for attachment whereas the latter obtains protection against parasitic infections.