Collaborative Research: Biodiversity and Ecosystem Function in Seaweed Communities

Stachowicz/Graham-0351778/1345合作研究：潮间带海藻群落的生物多样性和生态系统功能。物种多样性与生态系统性质之间的关系，如稳定性、恢复力和抗扰动能力，长期以来一直是生态学家感兴趣的理论话题。然而，近年来，人类活动加速了生物多样性的丧失，重新引起了人们对生态系统中生物多样性的功能后果的兴趣。尽管海洋栖息地的实验生态学有着悠久而富有成效的历史，人们对海洋底栖生物组合中维持多样性的原因也有相当的了解，但对这种多样性对群落其余部分的功能影响知之甚少。在这方面，海洋科学家远远落后于他们的陆地同事。该项目需要一系列实验室和野外实验，以研究潮间带大型藻类(海藻)多样性对初级生产力和消费物种的多样性、丰度和繁殖的影响。这项研究将从对加利福尼亚州博德加湾天然岩石潮间带群落的大型大型藻类多样性的相对大规模操纵(直径2米)开始。五个主要处理将由占该系统藻类覆盖率90%的4种藻类每种的单一养殖和4种混养组成。这项实验的结果将被用来研究多样性与生产者和消费者层面的各种生态系统功能之间的关系，包括大型藻类群落的初级生产力和生物量；个别藻类物种的生长、补充和繁殖；以及可移动和固着的无脊椎动物的多样性和丰度。对于目标2和目标3，将探讨造成上述任何影响的机制。例如，一些海藻在空气和水中的光合作用速率明显不同，这为物种之间的互补提供了一种潜在的机制。因此，在目标2中，将在实验室使用放氧(水)和二氧化碳吸收(空气)来探索多样性对空气和水中短期碳固定的影响。同样，在目标3中，将利用模拟藻类的实地实验来评估更多样化的藻类群落的结构复杂性是否有助于提高无脊椎动物的多样性或丰度。为了实现这一目标，还将测试多种藻类在混合养殖中提供的藻类饲料是否会导致地块中草食性无脊椎动物的良好生长、存活或繁殖力。在所有实验中，实验设计将使我们能够(A)确定是否存在多样性效应，以及(B)是否存在多样性效应，无论是由于单一物种的压倒性效应(即采样效应)，还是由于各种大型藻类发挥互补作用。鉴于地球正在经历前所未有的灭绝速度，了解生物多样性丧失的后果对管理工作至关重要，这项研究将使我们能够评估陆地成果对海洋系统管理的适用性。例如，海洋保护区的资源管理者和设计者必须了解生产者一级的多样性对于提高较高营养水平的产量和多样性以及沿海生态系统的整体功能的重要性。这项研究将提供一些海洋系统中关于这些问题的第一批数据，以及太平洋海洋岩石潮间带的第一批实验数据。该项目还将加强两所院校博士后、博士和硕士研究生以及本科生的经验和培训。(2004年1月15日编辑，J.Pawlik)

Stachowicz/Graham-0351778/1345Collaborative research: Biodiversity and ecosystem function in intertidal seaweed communities. The relationships between species diversity and ecosystem properties such as stability, resilience, and resistance to perturbation have long been topics of theoretical interest to ecologists. In recent years, however, accelerating loss of biodiversity due to human activities has renewed interest in the functional consequences of biodiversity in ecosystems. Although experimental ecology in marine habitats has a long and productive history, and there is a fair understanding of what maintains diversity in marine benthic assemblages, little is known about the functional consequences of that diversity for the rest of the community. In this regard marine scientists lag far behind their terrestrial colleagues. This project entails a series of lab and field experiments to examine the effects of intertidal macroalgal (seaweed) diversity on primary production and the diversity, abundance, and reproduction of consumer species. The study will begin with a relatively large scale manipulation (2 m diameter plots) of macroalgal diversity on natural rocky intertidal communities at Bodega Bay, California. Five main treatments will consist of a monoculture of each of the 4 algal species that comprise 90% of the algal cover in this system and the the 4-species polyculture. Results of this experiment will be used to examine the relationship between diversity and a variety of ecosystem functions at the producer and consumer level, including the primary productivity and biomass of the macroalgal community; the growth, recruitment and reproduction of individual algal species; and the diversity, and abundance of mobile and sessile invertebrates. For objectives 2 and 3, the mechanisms responsible for any of these effects will be explored. For example, some seaweeds exhibit significantly different rates of photosynthesis in air vs. water, providing a potential mechanism for complementarity among species. Thus, in objective 2, the effects of diversity on shorter term carbon fixation in air and in water will be explored in the lab using O2 evolution (water) and CO2 uptake (air). Similarly, in objective 3, field experiments with algal mimics will be used to assess whether the structural complexity of more diverse algal communities is responsible for enhanced inverterbrate diversity or abundance. For this objective, the possibility that the algal diet provided by multiple species in polycultures results in superior growth, survival or fecundity of herbivorous invertebrates in the plots will also be tested. In all experiments, the experimental design will allow us to (a) determine whether there is a diversity effect and (b) if there is a diversity effect, whether it is simply due to the overwhelming effect of one species (i.e., the sampling effect) or due to complementary roles played by the various macroalgal species. Given the unprecedented rate of extinctions the earth is experiencing, an understanding of the consequences of biodiversity loss is critical to management efforts and this study will allow us to assess the applicability of terrestrial results to the management of marine systems. For example, it is vital that resource managers and designers of Marine Protected Areas understand the degree to which diversity at the producer level is important for enhancing the production and diversity of higher trophic levels and the overall function of coastal ecosystems. This study will provide some of the first data anywhere in marine systems on these issues and the first experimental data for the Pacific marine rocky intertidal. This project will also enhance the experience and training of post-doctoral, Ph.D. and M.S. students, and undergraduate students at two institutions. (edited 15 Jan 04, J. Pawlik)