The development of ecosystem objectives for the Laurentian Great Lakes

Historically management of human use of ecosystems has been based around engineering and chemical approaches and through the construction of treatment facilities, effluent controls and setting chemical concentrations, both at end of pipe and in the aquatic environment. However, the general continued degradation of many ecosystems shows these approaches alone are insufficient. In the Laurentian Great Lakes the Great Lakes Water Quality Agreement was first signed in 1972 and ratified in 1978 and in 1987 tacitly acknowledged the problems with a chemical only approach by requiring the development of ecosystem objectives in the 1978 agreement. Furthermore, the agreement specifically identified numerical ecosystem objectives in the 1987 agreement. The evolution of ecosystem objectives in the Great Lakes has expanded from the strictly numerical objectives such as production of lake trout and abundance of the amphipod Pontoporeia hoyi. More recent developments in ecosystem objectives have been the inclusion of indicators for wildlife, habitat, human health and stewardship.Prepared as a discussion paper presented to the United Nations Economic Commission for Europe's seminar on an Ecosystems Approach to Water Management (May 27–31, 1991).     

From aquatic science to ecosystem health: a philosophical perspective

The development of an ecosystem (social, economic, environmental) approach to water management is traced from its origins in the Great Lakes of North America. The focus on health and integrity of ecosystems is an outgrowth of the Lamarckian concept of The Biosphere as a global system of matter, life, and mind. The driving forces behind the development of an ecosystem approach have been negative feedback from excessive demotechnic growth and faith that we can maintain a healthy relationship with Mother Earth.     

Biospheric foundations of the ecosystem approach to environmental management

The ecosystem approach to environmental management inter-relates social, economic and environmental factors. Its incorporation into the Great Lakes Water Quality Agreement of 1978 changed the focus of the Agreement from water in a political context to politics in an ecosystem context. Because ecosystems are open and dependent on Biospheric processes for their continued operation, the Biosphere (global ecosystem) emerges as a globally integrating factor in ecosystem management. Influences leading to development of the ecosystem approach in the Great Lakes Basin included: a politically shared resource in jeopardy, pollution, a common drinking water source, common enemies, advances in ecosystem theory, citizen groups, international political institutions, common economic and cultural ties, and a sense of crisis. A rationale is presented for viewing nations as politically defined ecosystems.     

Linking fish population dynamics to habitat conditions: insights from the application of a process-oriented approach to several Great Lakes species

One of the major challenges facing fishery scientists and managers today is determining how fish populations are influenced by habitat conditions. Many approaches have been explored to address this challenge, all of which involve modeling at one level or another. In this paper, we explore a process-oriented model approach whereby the critical population processes of birth and death rates are explicitly linked to habitat conditions. Application of this approach to five species of Great Lakes fishes including: walleye (Sander vitreus), lake trout (Salvelinus namaycush), smallmouth bass (Micropterus dolomieu), yellow perch (Perca flavescens), and rainbow trout (Onchorynchus mykiss), yielded a number of insights into the modeling process. One of the foremost insights is that processes determining movement and transport of fish are critical components of such models since these processes largely determine the habitats fish occupy. Because of the importance of fish location, an individual-based model appears to be a nearly inescapable modeling requirement. There is, however, a paucity of field-based data directly relating birth, death, and movement rates to habitat conditions experienced by individual fish. There is also a paucity of habitat information at a fine temporal and spatial scale for many important habitat variables. Finally, the general occurrence of strong ontogenetic changes in the response of different life stages to habitat conditions emphasizes the need for a modeling approach that considers all life stages in an integrated fashion.     

Ecosystem integrity in the Great Lakes Basin: an historical sketch of ideas and actions

The concepts of ecosystem and integrity effectively entered the binational political arena in the Great Lakes Basin in the early 1970's. They were brought together explicitly in the statement of the purpose of the 1978 Great Lakes Water Quality Agreement. The 1987 Protocol to that Agreement has helped to specify the practical meaning of ecosystem integrity of the Great Lakes Basin. The proceedings of a binational workshop in 1988, titled An Ecosystem Approach to the Integrity of the Great Lakes Basin in Turbulent Times, helped to clarify the conceptual meaning. An Ecosystem Charter for the Great Lakes-St. Lawrence River Basin was proposed in 1989 to help achieve more thorough implementation of the commitment to ecosystem integrity. The evolutionary emergence of this political concept and related practice is described in the paper.List of abbreviations used in the text CUSIS Canada-U.S. Inter-University Seminar Series - LAA Environmental Lakes Area - EPA Environmental Protection Agency - GLBC Great Lakes Basin Commission - GLC Great Lakes Commission - GLER Great Lakes Ecosystem Rehabilitation - GLFC Great Lakes Fishery Commission - GLSAB Great Lakes Science Advisory Board - GLU Great Lakes United - GLWQA Great Lakes Water Quality Agreement - HASP Heritage Area Security Plan - IBP International Biological Program - IJC International Joint Commission - IZAP Inundation Zone Adaptive Plan - LAMP Lake-wide Management Plan - LLRS Lake Levels Reference Study - MAB Man and the Biosphere program - NEPA National Environmental Policy Act - PLUARG Pollution from Land Use Activities Reference Group - RAP Remedial Action Plan - SCOL Salmonid Communities in Oligotrophic Lakes - SGLFMP Strategic Great Lakes Fishery Management Plan - SPOF Strategic Plan for Ontario Fisheries - UNESCO United Nations Educational, Scientific and Cultural Organization Aquatic Ecosystem Health and Management Society. Symposium at the University of Waterloo, July 23–25, 1990.     

Developing ecosystem objectives for the Great Lakes: policy,progress and public participation

Under the Great Lakes Water Quality Agreement of 1978 between the United States and Canada, as amended in 1987, an ecosystem objective with associated indicators for Lake Superior was adopted, and a commitment was made to develop ecosystem objectives and indicators for each of the other Great Lakes. Building upon a history of activities within the International Joint Commission related to the development of ecosystem indicators for Lake Superior and for mesotrophic waters, a binational Ecosystem Objectives Work Group (EOWG) has been established by the U.S. and Canada and charged with developing ecosystem objectives for the Great Lakes, beginning with Lake Ontario. These objectives are primarily biological in nature, in contrast to chemical objectives. The approach of the EOWG is to identify in sequence: (1) broad ecosystem goals, (2) a suite of objectives whose attainment would ensure achievement of the goals, and (3) one or more measurable indicators of progress toward meeting each objective. Societal values are reflected in the goals and objectives following consultation with competing users of ecosystem resources. Identification of appropriate indicators requires the assistance of technical experts. The experience of the EOWG in developing ecosystem objectives for Lake Ontario illustrates the application of this process.     

Towards defining aquatic ecosystem health for the Great Lakes

The Canada — U.S. Great Lakes Water Quality Agreement defines Areas of Concern as geographic areas that fail to meet the general or specific objectives of the Great Lakes Water Quality Agreement where such failure has caused or is likely to cause impairment of beneficial use or the area's ability to support aquatic life. Impairment of beneficial use is defined by the Agreement as a change in the physical, chemical or biological integrity sufficient to cause any one of 14 designated use impairments. In 1987 the International Joint Commission's Great Lakes Water Quality Board (GLWQB) recommended that criteria be developed to determine when ecosystem conditions have been impacted enough to warrant designation as an Area of Concern and when conditions have improved sufficiently to be delisted. Based on scientific input and policy considerations, the GLWQB adopted, in principle, a set of quantitative and qualitative listing/delisting criteria for each of the 14 use impairments. These criteria can be uniformly applied throughout the basin. Further, the GLWQB recommended future refinement of these criteria based on advances in science and public input.     

Predator-prey interactions in Lake Michigan: model predictions and recent dynamics

Synopsis Several years ago, we used a bioenergetics model to evaluate the impact of increasing salmonid stocking on the highly variable alewife forage base in Lake Michigan. At that time, we forecast an alewife population decline and the following system-wide effects: increased abundances of large zooplankton, decreased salmonid growth rates, increased diet breadth of salmonids, niche shifts among competitors of the alewife, increased alewife growth rates and increased densities of fishes suppressed by alewife. Alewives have continued to decline steadily since 1981 and are now reduced to a density similar to early outbreak levels in the early 1960s. Recent reports on fish growth rates, zooplankton size and fish community structure support our projections regarding system-wide responses to the alewife decline.     

基于管理目标的湖泊生态系统动力学

基于生态系统管理的目标,在对相关研究分析的基础上,依据生态系统生态学、淡水生态学的理论,提出了湖泊生态系统动力学研究的2个理论基础：生态系统管理和生态系统特征.在此基础上,分析得到湖泊生态系统动力学的研究方法体系,主要包括研究内容与技术路线、关键问题识别和动力学模拟、湖泊生态系统的适应性管理决策等部分.其中,湖泊生态系统结构和过程、湖泊中食物网营养动力学研究、生源要素循环、湖泊中关键过程的生态作用以及湖泊生态系统动力学模拟是研究的核心问题.此后,以P为主要的生源要素,将生态系统分为3个子过程：入流、出流和内部反馈,并以此建立了湖泊生态系统动力学的模型框架,以辅助于湖泊的生态系统管理.     

Depth gradients in food‐web processes linking habitats in large lakes: Lake Superior as an exemplar ecosystem

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Ecosystem services and management options as blanket indicators of ecosystem health

A pragmatic and integrative approach to evaluation of the environment combines ecosystem sciences, health sciences, and social sciences. Each has a crucial role to play: the ecosystem sciences provide information on the complex dynamics of ecosystems as they are influenced by stress and disturbance; the health sciences provide a methodology for systematic diagnosis of pathology, taxonomy of ills, and models for preventive as well as rehabilitative modes; the social sciences bring to the fore the importance of human values which are part and parcel of any health evaluation. The complexity of stress-response systems precludes anything approximating a complete understanding of mechanisms underpinning ecosystem transformations. However, the loss of ecosystem services and management options appears to be a general phenomenon that permits an overall evaluation of ecosystem health in both aquatic and terrestrial systems. Such blanket indicators take into account both the impairment of ecosystem function and societal values. This is illustrated by the history of ecosystem transformation in the Laurentian Lower Great Lakes and in the overharvested forest ecosystems of Eastern Canada. In both cases, cultural stress resulted in losses in highly valued ecosystem services and management options. These losses have been partially compensated for by new technologies that have permitted commercial use of the remaining lower quality resources. This process itself, however, may be pathological, reinforcing a degradation sequence rather than serving to restore ecosystem health.     

云南湿地生态系统鱼类物种濒危机制初探

湿地生态系统是鱼类生存、繁衍之地。由于云南地理位置特殊,鱼类多样性的研究及保护状况不仅在国内具有重要地位,对下游地区或国家也影响极大。因此,应引起国内、外生物学界和保护组织的高度重视。云南鱼类多样性的特点是：种类丰富、特有类群多;区民分复杂物种类型多样;种群小、数量少。对云南钱的种生存构成威胁的外在因素包括;围湖力沼泽化造成的栖息环境破坏,引种产生的物种生存空间及食物的竞争污染引起的生存环境质量下     

水生生态环境中捕食信息素的生态学效应

捕食信息素是捕食者释放的,能够引发猎物反捕食反应的化学信号。在水生生态系统中,捕食信息素在捕食者和猎物之间信息传递及协同进化过程中发挥着重要的作用,其生态学效应在国际上受到广泛关注。捕食信息素的来源有多种形式,研究中常使用养殖过捕食者的水溶液作为捕食信息素的来源。捕食信息素的作用效果受到捕食者和猎物的种类、信息素的浓度、观察的指标等多方面因素的影响。捕食信息素可以对水生生物的行为、形态和生活史特征等方面造成影响。水生生物通过感知捕食信息素来提前预知潜在的被捕食风险,并作出适应性调整,以降低被捕食的风险。在某些情况下,捕食信息素可以与污染物产生交互作用,从而干扰污染物对水生生物的毒性。对水生环境中捕食信息素的研究现状做了综述,介绍了当前对捕食信息素来源和理化性质等本质问题的认识,总结捕食信息素对水生生物行为、形态和生活史特征的影响,以及捕食信息素对污染物毒性的干扰,并分析了这一研究领域尚存在的困难和今后的研究方向。加强对捕食信息素的研究,将为解析水生环境中捕食者和猎物的生态关系提供新依据。     

Predator-prey interactions: effects of carp predation on Tubificid dynamics and carp production in experimental fishpond

Effects of predation by carp (Cyprinus carpio L) were analysed in an experimental fishpond where the main components of the benthic fauna were tubificids. Enclosures inaccessible to fishes were compared with the rest of the pond stocked with 30 young carps (1⁺). Fish predation reduced the density, biomass and production of prey; the production of Tubificidae inside the enclosures was 1.7 times higher than that of the part of the pond stocked with fishes. On the other hand tubificid turnover ratios (P/B) inside and outside enclosures were not significantly different (respectively 5.57 and 5.38), and the size distribution of tubificids was not significantly modified. The ratio of the energetic equivalent of net fish production to biomass of tubificids consumed was 5.59%.     

Biodiversity in the context of ecosystem services: the applied need for systems approaches

Recent evidence strongly suggests that biodiversity loss and ecosystem degradation continue. How might a systems approach to ecology help us better understand and address these issues? Systems approaches play a very limited role in the science that underpins traditional biodiversity conservation, but could provide important insights into mechanisms that affect population growth. This potential is illustrated using data from a critically endangered bird population. Although species-specific insights have practical value, the main applied challenge for a systems approach is to help improve our understanding of the role of biodiversity in the context of ecosystem services (ES) and the associated values and benefits people derive from these services. This has profound implications for the way we conceptualize and address ecological problems. Instead of focusing directly on biodiversity, the important response variables become measures of values and benefits, ES or ecosystem processes. We then need to understand the sensitivity of these variables to biodiversity change relative to other abiotic or anthropogenic factors, which includes exploring the role of variability at different levels of biological organization. These issues are discussed using the recent UK National Ecosystems Assessment as a framework.     

Sustainability of the Lake Superior Fish Community: Interactions in a Food Web Context

The restoration and rehabilitation of the native fish communities is a long-term goal for the Laurentian Great Lakes. In Lake Superior, the ongoing restoration of the native lake trout populations is now regarded as one of the major success stories in fisheries management. However, populations of the deepwater morphotype (siscowet lake trout) have increased much more substantially than those of the nearshore morphotype (lean lake trout), and the ecosystem now contains an assemblage of exotic species such as sea lamprey, rainbow smelt, and Pacific salmon (chinook, coho, and steelhead). Those species play an important role in defining the constraints and opportunities for ecosystem management. We combined an equilibrium mass balance model (Ecopath) with a dynamic food web model (Ecosim) to evaluate the ecological consequences of future alternative management strategies and the interaction of two different sets of life history characteristics for fishes at the top of the food web. Relatively rapid turnover rates occur among the exotic forage fish, rainbow smelt, and its primary predators, exotic Pacific salmonids. Slower turnover rates occur among the native lake trout and burbot and their primary prey—lake herring, smelt, deepwater cisco, and sculpins. The abundance of forage fish is a key constraint for all salmonids in Lake Superior. Smelt and Mysis play a prominent role in sustaining the current trophic structure. Competition between the native lake trout and the exotic salmonids is asymmetric. Reductions in the salmon population yield only a modest benefit for the stocks of lake trout, whereas increased fishing of lake trout produces substantial potential increases in the yields of Pacific salmon to recreational fisheries. The deepwater or siscowet morphotype of lake trout has become very abundant. Although it plays a major role in the structure of the food web it offers little potential for the restoration of a valuable commercial or recreational fishery. Even if a combination of strong management actions is implemented, the populations of lean (nearshore) lake trout cannot be restored to pre-fishery and pre-lamprey levels. Thus, management strategy must accept the ecological constraints due in part to the presence of exotics and choose alternatives that sustain public interest in the resources while continuing the gradual progress toward restoration. Received 10 December 1999; accepted 13 June 2000.     

Limnological aspects of the St. Clair River

The St. Clair River is a major navigable waterway transporting water southwards for 63 km from Lake Huron to Lake St. Clair at an average flow of 5 100 m3 s^-1. Water entering the river is low in suspended solids, organic carbon, phosphorus and nitrates, typical of clear, oligotrophic waters. In contrast to many large rivers, dissolved and colloidal solids account for 90 to 95 percent of the total solids load transported by the river, giving the river a turquoise colour common of glacial meltwater streams.The river supports a diverse floral and faunal community that includes 20 taxa of submergent macroflora, at least 300 benthic macroinvertebrates and 83 fishes. A number of exotic (European) species, including 3 plants, 4 molluscs and 11 fishes, occur in the river with the macroalga, Nitellopsis obtusa, zebra mussel (Dreissena polymorphora), Asian clam (Corbicula fluminea), and white perch (Morone americana) being the most recent invaders. Production is estimated to be 200 g m^-2 a^-1 ash-free dry mass for submergent macrophytes and periphyton, 7 g for macroinvertebrates and 5 g for fishes.The river also supports a variety of water-oriented recreational activities, is a source of municipal and industrial water, a receiver of municipal and industrial wastes, and a shipping corridor. Industrial discharges have adversely affected aquatic life, particularly in the nearshore areas along the Canadian shoreline south of Sarnia, Ontario. In addition, channel dredging and shoreline modifications (bulk-heading and backfilling) have destroyed large areas of valuable habitat in the main channel and along the shoreline. Improvements in the nearshore benthic macroinvertebrate community of the river over the past 20 years show that the river will respond to reductions in contaminants loadings.     

Predator control of ecosystem nutrient dynamics

Predators are predominantly valued for their ability to control prey, as indicators of high levels of biodiversity and as tourism attractions. This view, however, is incomplete because it does not acknowledge that predators may play a significant role in the delivery of critical life‐support services such as ecosystem nutrient cycling. New research is beginning to show that predator effects on nutrient cycling are ubiquitous. These effects emerge from direct nutrient excretion, egestion or translocation within and across ecosystem boundaries after prey consumption, and from indirect effects mediated by predator interactions with prey. Depending on their behavioural ecology, predators can create heterogeneous or homogeneous nutrient distributions across natural landscapes. Because predator species are disproportionately vulnerable to elimination from ecosystems, we stand to lose much more from their disappearance than their simple charismatic attractiveness.     

Biogenic silica as an estimate of siliceous microfossil abundance in Great Lakes sediments

Biogenic silica concentration (BSi) in sediment cores from the Great Lakes is evaluated as an estimate of siliceous microfossil abundance. A significant linear relationship was found between measured BSi and diatom valve abundance for sediment cores from the Bay of Quinte, Lake Ontario, Lake Erie, Lake Michigan and Lake Superior and between measured BSi and diatom biovolume for Lake Erie, Lake Michigan, and Lake Superior but not for Lake Ontario. Diatom silica predicted from diatom species abundance and an estimated silica content per cell in the Lake Erie cores accounted for 117% and 103% of measured BSi, respectively. By contrast, predicted diatom silica could only account for 28% of measured BSi in the Lake Michigan core and only 25% in the Lake Superior core. A few large diatoms with a large silica content per cell comprised a major portion of predicted diatom silica in all cores. The discrepancy between chemically measured BSi and the silica predicted from diatoms in the Lake Michigan and Lake Superior cores was partially due to the inability of the regression model, used to estimate diatom silica content, to account for different degrees of silicification in the diatom asemblages from the more dissolved silica rich Lake Michigan and Lake Superior.