CRB: Collaborative Research: The Direct and Indirect Effects of Biological Invasions on Biodiversity in New England Kelp Beds

9700331 Coyer人类在其自然范围之外引入的物种正在迅速使地球生物群同质化，并对陆地、水生和海洋栖息地的生物多样性构成重大威胁。虽然生物入侵对生物多样性的潜在影响已经被认识了几十年，但直到最近，大多数研究都集中在陆地或淡水而不是海洋栖息地。人为引进的海洋物种数量众多，对一些地方产生了巨大影响。虽然在过去的15年里，人们对引进的物种有了很多了解，但对海洋系统的概括是难以捉摸的。本研究将探讨引进物种对西北大西洋海带床群落的影响。具体而言，本研究将研究西北大西洋引入藻Codium fragile和本地海带群落的草食和竞争的相互作用，苔藓虫对这些群落中海带的间接影响，以及Codium的增加和海带生物量的减少对将海藻床作为苗圃栖息地的鱼类和十足类动物的人口统计的影响。新英格兰的海带床群落在两种交替状态之间转换：一个物种丰富的群落以海带为主，一个物种贫乏的群落以海胆和甲壳珊瑚藻为主。最近，一个由引进的单一绿藻组成的新群落，脆弱毛囊藻，现在在该地区普遍存在。此外，苔藓虫的引入似乎也严重影响了海带床群落。通过一系列的多因素实验和描述性研究，本研究将阐明这种群落结构转变的原因，从而解释这些海带群落中人类引起的生物多样性急剧丧失的机制。

9700331 Coyer Human introductions of species outside their natural range are rapidly homogenizing the earth's biota, and are a major threat to biodiversity in terrestrial, aquatic and marine habitats. Although the potential impact of biological invasions on biodiversity has been recognized for decades, until recently, most research has focused on terrestrial or freshwater rather than marine habitats. Anthropogenic introductions of marine species are numerous and have had a dramatic impact in some locals. While much has been learned about introduced species over the last 15 years, generalizations relative to marine systems are elusive. This study will address the effects of introduced species on kelp bed communities in the northwest Atlantic Ocean. Specifically, this research will examine the interactive effects of herbivory and competition on the introduced alga Codium fragile and the native kelp community of the northwest Atlantic, the indirect effects of a bryozoan on kelps in these communities, and the impact of increasing Codium and decreasing kelp biomass on the demography of fishes and decapods that use seaweed beds as nursery habitats. The kelp bed communities of New England shift between two alternate states: a species-rich community dominated by laminarian kelps, and a species-poor community dominated by sea urchins and crustose coralline algae. Recently, a new community consisting of a monoculture of the introduced green alga, Codium fragile tomentosoides, is now prevalent in the region. In addition the introduction of a bryozoan also appears to have severely impacted kelp bed communities. Using a series of multi-factor experiments and descriptive studies, this research will elucidate the causes of this shift in community structure, and therefore explain the mechanisms underlying the dramatic, human-induced loss of biodiversity in these kelp communities.