COLLABORATIVE RESEARCH: Biodiversity and ecosystem function in intertidal seaweed communities

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特性之间的关系，如稳定性、恢复力和对扰动的抵抗力，长期以来一直是生态学家感兴趣的理论话题。然而，近年来，由于人类活动导致的生物多样性的加速丧失重新引起了人们对生态系统中生物多样性功能后果的兴趣。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，并且对维持海洋底栖生物群落多样性的原因有了相当的理解，但对这种多样性对其他群落的功能后果知之甚少。在这方面，海洋科学家远远落后于陆地科学家。该项目需要进行一系列实验室和实地实验，以检查潮间带大型藻（海藻）多样性对初级生产和消费物种的多样性、丰度和繁殖的影响。这项研究将从一个相对大规模的操作（2米直径的地块）开始，对加州博德加湾天然岩石潮间带群落的大型藻类多样性进行研究。五种主要的处理方法将包括对占该系统藻类覆盖面积90%的4种藻类中的每一种进行单种培养和4种混养。这一试验的结果将用于在生产者和消费者一级检查多样性与各种生态系统功能之间的关系，包括大藻群落的初级生产力和生物量；个别藻类的生长、繁殖和繁殖；还有丰富多样的活动无脊椎动物。对于目标2和3，将探讨造成这些影响的机制。例如，一些海藻在空气和水中表现出明显不同的光合作用速率，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，多样性对空气和水中短期碳固定的影响将在实验室中通过O2进化（水）和CO2吸收（空气）来探索。同样，在目标3中，模拟藻类的现场实验将用于评估更多样化的藻类群落的结构复杂性是否对无脊椎动物多样性或丰度的增强负责。为此目的，还将测试由多种物种在混合培养中提供的藻类饮食导致草食性无脊椎动物在小区中优越的生长、存活或繁殖力的可能性。在所有的实验中，实验设计将允许我们(a)确定是否存在多样性效应，(b)如果存在多样性效应，它是仅仅由于一个物种的压倒性效应（即采样效应）还是由于各种大型藻类物种发挥的互补作用。鉴于地球正在经历前所未有的物种灭绝速度，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结果对海洋系统管理的适用性。例如，至关重要的是，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提高高营养级的生产和多样性以及沿海生态系统的总体功能的重要程度。这项研究将提供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、博士和硕士学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)