Jane Lubchenco

Effect of aquaculture on world fish supplies

Global production of farmed fish and shellfish has more than doubled in the past 15 years. Many people believe that such growth relieves pressure on ocean fisheries, but the opposite is true for some types of aquaculture. Farming carnivorous species requires large inputs of wild fish for feed. Some aquaculture systems also reduce wild fish supplies through habitat modification, wild seedstock collection and other ecological impacts. On balance, global aquaculture production still adds to world fish supplies; however, if the growing aquaculture industry is to sustain its contribution to world fish supplies, it must reduce wild fish inputs in feed and adopt more ecologically sound management practices.

Complexity of Coupled Human and Natural Systems

Integrated studies of coupled human and natural systems reveal new and complex patterns and processes not evident when studied by social or natural scientists separately. Synthesis of six case studies from around the world shows that couplings between human and natural systems vary across space, time, and organizational units. They also exhibit nonlinear dynamics with thresholds, reciprocal feedback loops, time lags, resilience, heterogeneity, and surprises. Furthermore, past couplings have legacy effects on present conditions and future possibilities.

Challenges in the quest for keystones

Mary E. Power is a professor in the Department of Integrative Biology, University of California, Berkeley, CA 94720. David Tilman is a professor in the Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN 55108. James A. Estes is a wildlife biologist in the National Biological Service, Institute of Marine Science, University of California, Santa Cruz, CA 95064. Bruce A. Menge is a professor in the Department of Zoology, Oregon State University, Corvallis, OR 97331. William J. Bond is a professor doctor in the Department of Botany, University of Cape Town, Rondebosch 7700 South Africa. L. Scott Mills is an assistant professor in the Wildlife Biology Program, School of Forestry, University of Montana, Missoula, MT 59812. Gretchen Daily is Bing Interdisciplinary Research Scientist, Department of Biological Science, Stanford University, Stanford, CA 94305. Juan Carlos Castilla is a full professor and marine biology head in Facultad de Ciencias Biologicas, Pontificia Universidad Catolica de Chile, Casilla 114-D, Santiago, Chile. Jane Lubchenco is a distinguished professor in the Department of Zoology, Oregon State University, Corvallis, OR 97331. Robert T. Paine is a professor in the Department of Zoology, NJ-15, University of Washington, Seattle, WA 98195. ? 1996 American Institute of Biological Sciences. A keystone species is

PLANT SPECIES DIVERSITY IN A MARINE INTERTIDAL COMMUNITY: IMPORTANCE OF HERBIVORE FOOD PREFERENCE AND ALGAL COMPETITIVE ABILITIES

Field experiments demonstrate that the herbivorous marine snail Littorina littorea controls the abundance and type of algae in high intertidal tide pools in New England. Here the highest species diversity of algae occurs at intermediate Littorina densities. This unimodal relationship between algal species diversity and herbivore density occurs because the snails preferred food is competitively dominant in tide pool habitats. Moderate grazing allows inferior algal species to persist and intense grazing eliminates most individuals and species. In contrast to pools, on emergent substrata where the preferred food is competitively inferior, this herbivore decreases algal diversity. Thus, the effect of this consumer on plant species diversity depends on the relationship between herbivore food preference and competitive abilities of the plants. These results may apply to most generalized consumers and provide a framework within which previously confusing results can be understood. Thus predators or herbivores do not simply increase or decrease species diversity of their food, but can potentially do both. The precise effect a consumer has probably depends both on the relationship between its preferences and the foods competitive abilities and on the intensity of the grazing or predation pressure.

MARINE RESERVES ARE NECESSARY BUT NOT SUFFICIENT FOR MARINE CONSERVATION

The intensity of human pressure on marine systems has led to a push for stronger marine conservation efforts. Recently, marine reserves have become one highly advocated form of marine conservation, and the number of newly designated reserves has increased dramatically. Reserves will be essential for conservation efforts because they can provide unique protection for critical areas, they can provide a spatial escape for intensely exploited species, and they can potentially act as buffers against some management miscalculations and unforeseen or unusual conditions. Reserve design and effectiveness can be dramatically improved by better use of existing scientific understanding. Reserves are insufficient protection alone, however, because they are not isolated from all critical impacts. Communities residing within marine reserves are strongly influenced by the highly variable conditions of the water masses that continuously flow through them. To a much greater degree than in terrestrial systems, the scales of fundamental processes, such as population replenishment, are often much larger than reserves can encompass. Further, they offer no protection from some important threats, such as contamination by chemicals. Therefore, without adequate protection of species and ecosystems outside reserves, effectiveness of reserves will be severely compromised. We outline conditions under which reserves are likely to be effective, provide some guidelines for increasing their conservation potential, and suggest some research priorities to fill critical information gaps. We strongly support vastly increasing the number and size of marine reserves; at the same time, strong conservation efforts outside reserves must complement this effort. To date, most reserve design and site selection have involved little scientific justification. They must begin to do so to increase the likelihood of attaining conservation objectives.

Coupled Human and Natural Systems

Abstract Humans have continuously interacted with natural systems, resulting in the formation and development of coupled human and natural systems (CHANS). Recent studies reveal the complexity of organizational, spatial, and temporal couplings of CHANS. These couplings have evolved from direct to more indirect interactions, from adjacent to more distant linkages, from local to global scales, and from simple to complex patterns and processes. Untangling complexities, such as reciprocal effects and emergent properties, can lead to novel scientific discoveries and is essential to developing effective policies for ecological and socioeconomic sustainability. Opportunities for truly integrating various disciplines are emerging to address fundamental questions about CHANS and meet societys unprecedented challenges.

The Sustainable Biosphere Initiative: An Ecological Research Agenda: A Report from the Ecological Society of America

In this document, the Ecological Society of America proposes the Sustainable Biosphere Initiative (SBI), an initiative that focuses on the necessary role of ecological science in the wise management of Earths resources and the maintenance of Earths life support systems. This document is intended as a call to arms for all ecologists, but it will also serve as a means to communicate with individuals in other disciplines with whom ecologists must join forces to address a common predicament. This document focuses primarily on the acquisition of ecological knowledge. It identifies the ecological research programs of highest priority and recommends steps required to pursue research objectives. The document also lays the groundwork for improving the communication and application of ecological knowledge. The SBI proposes three research priorities: global change; biological diversity; and sustainable ecological systems.

ECOLOGICAL CRITERIA FOR EVALUATING CANDIDATE SITES FOR MARINE RESERVES

Several schemes have been developed to help select the locations of marine reserves. All of them combine social, economic, and biological criteria, and few offer any guidance as to how to prioritize among the criteria identified. This can imply that the relative weights given to different criteria are unimportant. Where two sites are of equal value ecologically; then socioeconomic criteria should dominate the choice of which should be protected. However, in many cases, socioeconomic criteria are given equal or greater weight than ecological considerations in the choice of sites. This can lead to selection of reserves with little biological value that fail to meet many of the desired objectives. To avoid such a possibility, we develop a series of criteria that allow preliminary evaluation of candidate sites according to their relative biological values in advance of the application of socioeconomic criteria. We include criteria that,. while not strictly biological, have a strong influence on the species present or ecological processes. Out scheme enables sites to be assessed according to their biodiversity, the processes which underpin that diversity, and the processes that support fisheries and provide a spectrum of other services important to people. Criteria that capture biodiversity values include biogeographic representation, habitat representation and heterogeneity, and presence of species or populations of special interest (e.g., threatened species). Criteria that capture sustainability of biodiversity and fishery values include the size of reserves necessary to protect viable habitats, presence of exploitable species, vulnerable life stages, connectivity among reserves, links among ecosystems, and provision of ecosystem services to people. Criteria measuring human and natural threats enable candidate sites to be eliminated from consideration if risks are too great, but also help prioritize among sites where threats can be mitigated by protection. While our criteria can be applied to the design of reserve networks, they also enable choice of single reserves to be made in the context of the attributes of existing protected areas. The overall goal of our scheme is to promote the development of reserve networks that will maintain biodiversity and ecosystem functioning at large scales. The values of eco-system goods and services for people ultimately depend on meeting this objective.

Emergence of Anoxia in the California Current Large Marine Ecosystem

Eastern boundary current systems are among the worlds most productive large marine ecosystems. Because upwelling currents transport nutrient-rich but oxygen-depleted water onto shallow seas, large expanses of productive continental shelves can be vulnerable to the risk of extreme low-oxygen events. Here, we report the novel rise of water-column shelf anoxia in the northern California Current system, a large marine ecosystem with no previous record of such extreme oxygen deficits. The expansion of anoxia highlights the potential for rapid and discontinuous ecosystem change in productive coastal systems that sustain a major portion of the worlds fisheries.

Upwelling-driven nearshore hypoxia signals ecosystem and oceanographic changes in the northeast Pacific.

Seasonal development of dissolved-oxygen deficits (hypoxia) represents an acute system-level perturbation to ecological dynamics and fishery sustainability in coastal ecosystems around the globe. Whereas anthropogenic nutrient loading has increased the frequency and severity of hypoxia in estuaries and semi-enclosed seas, the occurrence of hypoxia in open-coast upwelling systems reflects ocean conditions that control the delivery of oxygen-poor and nutrient-rich deep water onto continental shelves. Upwelling systems support a large proportion of the worlds fisheries, therefore understanding the links between changes in ocean climate, upwelling-driven hypoxia and ecological perturbations is critical. Here we report on the unprecedented development of severe inner-shelf (<70 m) hypoxia and resultant mass die-offs of fish and invertebrates within the California Current System. In 2002, cross-shelf transects revealed the development of abnormally low dissolved-oxygen levels as a response to anomalously strong flow of subarctic water into the California Current System. Our findings highlight the sensitivity of inner-shelf ecosystems to variation in ocean conditions, and the potential impacts of climate change on marine communities.