Invasive bryozoan alters interaction between a native grazer and its algal food
Invasive bryozoan alters interaction between a native grazer and its algal food
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DOI：
10.1017/s0025315412001683
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发表时间：
2013-08-01
影响因子：
1.2
通讯作者：
Scheibling, Robert E.
中科院分区：
文献类型：
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作者：
O'Brien, John M.;Krumhansl, Kira A.;Scheibling, Robert E.
附生苔藓动物膜生苔藓虫包裹在海带叶片的表面，导致加拿大新斯科舍省大西洋海岸附近的海带床反复发生大规模落叶事件。腹足类动物LacunaVincta吃海带，产生的穿孔削弱了叶片组织，增加了碎片率。我们于2010年11月和12月在实验室进行了非选择性和选择性实验，通过测量蜗牛对苔藓虫壳和非苔藓壳海带(Saccharina Latisima)的捕食率来评估膜藻和L.vincta之间的相互作用。在非选择试验中，日粮对放牧率没有影响。然而，在选择性实验中，文氏藻对无壳海带的摄食量显著高于有壳海带(7.1 mg蜗牛(-1)d(-1))，而无壳海带的摄食率(3.8 mg蜗牛(-1)d(-1))几乎是非选择性实验中的两倍，这表明蜗牛可能会避开部分有壳海带叶片上的膜藻群落。在结壳和未结壳的海带上，饲养四周的钉螺的生长、繁殖和存活没有受到饲料的影响。通过将放牧危害集中在叶片的非结壳区域，L.vincta可能与膜毛霉菌协同作用，增加叶片断裂和树冠损失的可能性。这种入侵苔藓虫的间接作用可能会增加其对本地海带床现存量的直接影响，并将碎屑输出到邻近的群落。
The epiphytic bryozoan Membranipora membranacea encrusts the surface of kelp blades, causing recurrent large-scale defoliation events in kelp beds off the Atlantic coast of Nova Scotia, Canada. The gastropod Lacuna vincta grazes kelp, creating perforations that weaken blade tissues and increase the fragmentation rate. We assess the interaction between M. membranacea and L. vincta by measuring the grazing rate of snails on bryozoan-encrusted and non-encrusted kelp (Saccharina latissima) in no-choice and choice experiments in the laboratory conducted in November and December 2010. There was no effect of diet on grazing rate in no-choice experiments. In choice experiments, however, L. vincta grazed significantly more non-encrusted than encrusted kelp (7.1 versus 1.1 mg snail(-1) d(-1)), and grazing rate of non-encrusted kelp was almost twice that in the no-choice experiment (3.8 mg snail(-1) d(-1)), indicating that snails may avoid colonies of M. membranacea on partially encrusted kelp blades. We found no effect of diet on growth, reproduction and survival of snails maintained for four weeks on encrusted or non-encrusted kelp. By concentrating grazing damage on non-encrusted areas of blades, L. vincta may act synergistically with M. membranacea to increase the likelihood of blade breakage and canopy loss. This indirect effect of the invasive bryozoan could augment its direct effect on the standing biomass of native kelp beds and detrital export to adjacent communities.