Multiple Stressors in River Ecosystems: Status, Impacts and Prospects for the Future provides a comprehensive and current overview on the topic as written by leading river scientists who discuss the relevance of co-occurring stressors for river ecosystems. River ecosystems are subject to multiple stressors that threaten their ecological status and the ecosystem services they provide. This book updates the reader's knowledge on the response and management of river ecosystems to multi-stress situations occurring under global change. Detailing the risk for biodiversity and functioning in a case-study approach, it provides insight into methodological issues, also including the socioeconomic implications. - Presents a case study approach and geographic description on the relevance of multiple stressors on river ecosystems in different biomes - Gives a uniquely integrated perspective on different stressors, including their interactions and joint effects, as opposed to the traditional one-by-one approach - Compiles state-of-the-art methods and technologies in monitoring, modeling and analyzing river ecosystems under multiple stress conditions

Ecosystem research has emerged in recent decades as a vital, successful, and sometimes controversial approach to environmental science. This book emphasizes the idea that much of the progress in ecosystem research has been driven by the emergence of new environmental problems that could not be addressed by existing approaches. By focusing on successes and limitations of ecosystems studies, the book explores avenues for future ecosystem-level research.

Marine mammals face a large array of stressors, including loss of habitat, chemical and noise pollution, and bycatch in fishing, which alone kills hundreds of thousands of marine mammals per year globally. To discern the factors contributing to population trends, scientists must consider the full complement of threats faced by marine mammals. Once populations or ecosystems are found to be at risk of adverse impacts, it is critical to decide which combination of stressors to reduce to bring the population or ecosystem into a more favorable state. Assessing all stressors facing a marine mammal population also provides the environmental context for evaluating whether an additional activity could threaten it. Approaches to Understanding the Cumulative Effects of Stressors on Marine Mammals builds upon previous reports to assess current methodologies used for evaluating cumulative effects and identify new approaches that could improve these assessments. This review focuses on ways to quantify exposure-related changes in the behavior, health, or body condition of individual marine mammals and makes recommendations for future research initiatives.

There is a pressing need for developing and testing a general set of theories in order to provide a confident basis for prediction of multiple stressor effects. Confident prediction is central to confident decision making in water pollution control. Consequently, WERF commissioned this study, which has as its goal to provide a study design based on good science that helps establish a general, conceptual approach to multiple stressors. The objectives addressed in this report are: (1) review and critique the existing body of knowledge for multiple stressors; (2) develop a searchable, annotated bibliography of multiple stressor research; and, (3) identify gaps in the body of knowledge. A rigorous, theoretical basis for the prediction of multiple stressor effects could not be developed from the literature on experimental studies of multiple stressor effects in aquatic ecosystems. Despite the wealth of observational data, the existence of several useful tools for interpretation of cause/effect relationships (including formal Stressor Identification methods), and the studies reviewed in this report, there are no tools that allow a confident, a priori, prediction of ecosystem response to multiple stressors. The current literature provides, at best, a series of site-specific glimpses of the response of ecological communities and ecosystems to multiple stressors. There is seldom, if ever, any reference to a more generalized model of multiple stressor effects apart from the discussion of the expectations regarding additivity versus synergism. Many articles that purport to be multiple stressor studies do not go beyond an inventory of the various stresses and upsets affecting the ecosystem, without attempting to assess the interactions among them.

Ecotoxiclogical risk from multiple stressors covers any situation where org- isms are exposed to a combination of environmental stressors. These include physical and chemical pollutants as well as other stressors such as parasites and environmental impact (e. g. , climate change or habitat loss). The combi- tion of stressors can result in increased risk to organisms (either additive or synergistic effects) or decreased effects (protective or antagonistic effects). The multiple stressor challenge is an international, multi-disciplinary problem requiring an international, multi-disciplinary approach. The c- rent approach to multiple stressors is to examine one stressor at a time and assume additivity. Little work has been done on combinations of stressors such that potential interactions can be determined. The problem is very complex. Multiple stressors pose a whole spectrum of challenges that range from basic science to regulation, policy and gove- ance. The challenges raise fundamental questions about our understanding of the basic biological response to stressors, as well as the implications of those uncertainties in environmental risk assessment and management. In addition to the great breadth, there is also great depth in the research ch- lenges, largely due to the complexity of the issues. From a basic science point of view, many of the mechanisms and processes under investigation are at the cutting edge of science — involving new paradigms such as genomic ins- bility and bystander effects.

The science of ecotoxicology and the practice of ecological risk assessment are evolving rapidly. Ecotoxicology as a subject area came into prominence in the 1960s after the publication of Rachel Carson's book on the impact of pesticides on the environment. The rise of public and scientific concern for the effects of chemical pollutants on the environment in the 1960s and 1970s led to the development of the discipline of ecotoxicology, a science that takes into account the effects of chemicals in the context of ecology. Until the early 1980s, in spite of public concern and interest among scientists, the assessment of ecological risks associated with natural or synthetic pollutants was not considered a priority issue by most government. However, as the years passed, a better understanding of the importance of ecotoxicology emerged and with it, in some countries, the progressive formalization of an ecological risk assessment process. Ecological risk assessment is a conceptual tool for organizing and analyzing data and information to evaluate the likelihood that one or more stressors are causing or will cause adverse ecological effects. Ecological risk assessment allows risk managers to consider available scientific information when selecting a course of action, in addition to other factors that may affect their decision (e. g. , social, legal, political, or economic). Ecological risk assessment includes three phases (problem formulation, analysis, and risk characterization).

Not all stress is stressful; instead, it appears that stress in the environment, below the mutation threshold, is essential for many subtle manifestations of population structures and biodiversity, and has played a substantial role in the evolution of life. Intrigued by the behavior of laboratory animals that contradicted our current understanding of stress, the author and his group studied the beneficial effects of stress on animals and plants. The seemingly “crazy” animals demonstrated that several stress paradigms are outdated and have to be reconsidered. The book describes the general stress responses in microorganisms, plants, and animals to abiotic and biotic, to natural and anthropogenic stressors. These stress responses include the activation of oxygen, the biotransformation system, the stress proteins, and the metal-binding proteins. The potential of stress response lies in the transcription of genes, whereas the actual response is manifested by proteins and metabolites. Yet, not all stress responses are in the genes: micro-RNAs and epigenetics play central roles. Multiple stressors, such as environmental realism, do not always act additively; they may even diminish one another. Furthermore, one stressor often prepares the subject for the next one to come and may produce extended lifespans and increased offspring numbers, thus causing shifts in population structures. This book provides the first comprehensive analysis of the ecological and evolutionary effects of stress.

Many Microorganisms and some macro-organisms can live under extreme conditions. For example, high and low temperature, acidic and alkaline conditions, high salt areas, high pressure, toxic compounds, high level of ionizing radiation, anoxia and absence of light, etc. Many organisms inhabit environments characterized by more than one form of stress (Polyextremophiles). Among them are those who live in hypersaline and alkaline, hot and acidic, cold/hot and high hydrostatic pressure, etc. Polyextremophiles found in desert regions have to copy with intense UV irradiation and desiccation, high as well as low temperatures, and low availability of water and nutrients. This book provides novel results of application to polyextremophiles research ranging from nanotechnology to synthetic biology to the origin of life and beyond.

The research of the last decade has demonstrated that ecosystems and human systems are influenced by multiple factors, including climate, land use, and the by-products of resource use. Understanding the net impact of a suite of simultaneously occurring environmental changes is essential for developing effective response strategies. Using case studies on drought and a wide range of atmosphere-ecosystem interactions, a workshop was held in September 2005 to gather different perspectives on multiple stress scenarios. The overarching lesson of the workshop is that society will require new and improved strategies for coping with multiple stresses and their impacts on natural socioeconomic systems. Improved communication among stakeholders; increased observations (especially at regional scales); improved model and information systems; and increased infrastructure to provide better environmental monitoring, vulnerability assessment, and response analysis are all important parts of moving toward better understanding of and response to situations involving multiple stresses. During the workshop, seven near-term opportunities for research and infrastructure that could help advance understanding of multiple stresses were also identified.