Physiological ecology meets climate change

In this article, we pointed out that understanding the physiology of differential climate change effects on organisms is one of the many urgent challenges faced in ecology and evolutionary biology. We explore how physiological ecology can contribute to a holistic view of climate change impacts on organisms and ecosystems and their evolutionary responses. We suggest that theoretical and experimental efforts not only need to improve our understanding of thermal limits to organisms, but also to consider multiple stressors both on land and in the oceans. As an example, we discuss recent efforts to understand the effects of various global change drivers on aquatic ectotherms in the field that led to the development of the concept of oxygen and capacity limited thermal tolerance (OCLTT) as a framework integrating various drivers and linking organisational levels from ecosystem to organism, tissue, cell, and molecules. We suggest seven core objectives of a comprehensive research program comprising the interplay among physiological, ecological, and evolutionary approaches for both aquatic and terrestrial organisms. While studies of individual aspects are already underway in many laboratories worldwide, integration of these findings into conceptual frameworks is needed not only within one organism group such as animals but also across organism domains such as Archaea, Bacteria, and Eukarya. Indeed, development of unifying concepts is relevant for interpreting existing and future findings in a coherent way and for projecting the future ecological and evolutionary effects of climate change on functional biodiversity. We also suggest that OCLTT may in the end and from an evolutionary point of view, be able to explain the limited thermal tolerance of metazoans when compared to other organisms.     

Potential roles for recently discovered chytrid parasites in the dynamics of harmful algal blooms

Zoosporic true fungi belonging to the phylum Chytridiomycota, commonly referred to as chytrids, are ubiquitous in aquatic environments, however their role in phytoplankton population and eco-physiological dynamics is not fully understood. With the rising occurrence of harmful algal blooms (HABs) of phytoplankton worldwide, there is a growing need to investigate the factors affecting toxicity in algae, with a view to determining the significance of these factors in light of the current trends in global climate change. In this review we present current knowledge regarding the parasitism of phytoplankton by chytrids, including incidence of chytrid epidemics, methodologies used in their isolation and classification, their life cycles and infection strategies, and their potential role in toxin production in algae. We outline key areas in phytoplankton host–parasite dynamics that are poorly understood, discuss the potential roles of chytrids in these areas, and highlight future research directions for the furthering of our knowledge regarding algal ecophysiology. The synthesis of current knowledge in these fields will help researchers develop new hypotheses to further our understanding of primary production in aquatic ecology, and thus enhance our understanding of aquatic ecology, for more effective management of aquatic ecosystems.     

People as Ecological Participants in Ecological Restoration

In 1987, Bradshaw proposed that ecological restoration is the ultimate “acid test” of our understanding the functioning of ecosystems ( Bradshaw 1987 ). Although this concept is widely supported academically, how it can be applied by restoration practitioners is still unclear. This is an issue not limited to Bradshaw’s acid test, but moreover, reflects a general difficulty associated with the polarization between conceptual restoration (restoration ecology) and practical restoration (ecological restoration), where each has functioned to certain degree in isolation of the other. Outside of the more obvious pragmatic reasons for the relative independence between ecological restoration and restoration ecology, we propose that a more contentious explanation is that the approach taken toward understanding ecosystem development in restoration ecology is tangential to what actually takes place in ecological restoration. Current paradigms assume that the process of ecosystem development in restoration should follow the developmental trajectories suggested by classical ecological succession models. However, unlike these models, ecosystem development in restoration is, at least initially, largely manipulated by people, rather than by abiotic and biotic forces alone. There has been little research undertaken to explore how restoration activities impact upon or add to the extant ecological processes operating within a restoration site. Consequently, ecological restoration may not be so much an acid test of our understanding the functioning of ecosystems, but rather, an acid test of our understanding mutually beneficial interactions between humans and ecosystems.     

Ultraviolet Insights: Attempting to Resolve Enigmatic Patterns in Pelagic Freshwaters – The Historical Context and a View to the Future

While great advances have been made in our understanding of pelagic freshwater communities and ecosystems in recent years, several unexplained patterns continue to evade our understanding. While no single factor can explain these enigmatic patterns, recent increases in our understanding of the ecology of ultraviolet radiation (UV) are consistent with UV playing an important role. Here we present a brief overview of why UV has historically received so little attention in pelagic freshwater ecosystems, review some of the important aspects of the ecology of UV that are important to these enigmatic patterns, and discuss how this new understanding of the ecology of UV may provide some insights into these previously unexplained patterns. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

An ecological perspective in aquatic ecotoxicology: Approaches and challenges

This paper aims to highlight the considerable potential of a better integration of ecological theory in aquatic ecotoxicology. It outlines how community ecology, studies on trophic interaction and disturbance ecology could provide an enhanced theoretical basis for aquatic ecotoxicology and increase ecological relevance in environmental risk assessment of chemicals. Based on the literature and own research, approaches from aquatic ecotoxicology are presented, which are based on ecological considerations and address a higher level of biological complexity for risk assessment strategies of chemicals. The concepts of species-sensitivity distribution (SSD), pollution-induced community tolerance (PICT), the use of model ecosystems and the sediment quality triad (SQT) in ecological risk assesment as well as inputs from ecotoxicology into landscape ecology are illustrated. These examples aim to evidence aquatic ecotoxicology as a rewarding field of ecological research.     

水环境中药物和个人护理品(PPCPs)的污染现状及对藻类的毒性研究进展

药物和个人护理品(PPCPs)因持续排放到水环境且对水生态环境和人类健康造成潜在威胁而受到广泛关注.藻类作为水体重要的初级生产者,对水体的生态平衡和稳定起着重要的作用.本文围绕地表水PPCPs污染,介绍了不同国家和地区地表水体中PPCPs的浓度分布和污染特征,并从毒性效应、生物累积及潜在的生态风险等方面,综述了PPCPs对藻类的污染生态学研究进展,阐述PPCPs对藻类的毒性效应及机制,PPCPs在藻类中的生物累积,以及地表水体PPCPs的生态风险,为地表水体PPCPs的相关标准制定和修订,以及水体生态环境健康风险评价提供参考.     

The prominence of and biases in biodiversity and ecosystem functioning research

The sub-discipline of biodiversity and ecosystem functioning (BEF) has emerged as a central topic in contemporary ecological research. However, to date no study has evaluated the prominence and publication biases in BEF research. Herein we report the results of a careful quantitative assessment of BEF research published in five core general ecology journals from 1990 to 2007 to determine the position of BEF research within ecology, identify patterns of research effort within BEF research, and discuss their probable proximal and historical causes. The relative importance of BEF publications increased exponentially during the period analyzed and was significantly greater than the average growth of ecological literature, affirming the prominence of BEF as a current paradigm in ecology. However, BEF research exhibited a strong bias toward experimental studies on terrestrial plant communities, with significantly lower effort devoted to the functional aspects of biodiversity in aquatic systems, multiple trophic level systems, and animal or microbial communities. Such trends may be explained by a combination of methodological adequacy and historic epistemological differences in ecological thinking. We suggest that BEF researchers should direct more effort toward the study of aquatic systems and animal communities, emphasize long-term and trophically complex experiments, such as those with multi-trophic microbial communities, employ larger-scale field observational studies and increase the use of integrative and theoretical studies. Many technical and analytical methodologies that are already employed in ecological research, such as stable isotopes, paleobiology, remote sensing, and model selection criteria, can facilitate these aims. Overcoming the above-mentioned shortcomings of current BEF research will greatly improve our ability to predict how biodiversity loss will affect ecosystem processes and services in natural ecosystems.     

Integrative freshwater ecology and biodiversity conservation

Freshwater ecosystems provide goods and services of critical importance to human societies, yet they are among the most heavily altered ecosystems with an overproportional loss of biodiversity. Major threats to freshwater biodiversity include overexploitation, water pollution, fragmentation, destruction or degradation of habitat, and invasions by non-native species. Alterations of natural flow regimes by man-made dams, land-use changes, river impoundments, and water abstraction often have profound impacts on lotic communities. An understanding of the functional interactions and processes in freshwater ecosystems presents a major challenge for scientists, but is crucial for effective and sustainable restoration. Most conservation approaches to date have considered single species or single level strategies. In contrast, the concept of ‘Integrative Freshwater Ecology and Biodiversity Conservation’ (IFEBC) proposed herein addresses the interactions between abiotic and biotic factors on different levels of organization qualitatively and quantitatively. It consequently results in a more holistic understanding of biodiversity functioning and management. Core questions include modeling of the processes in aquatic key habitats and their functionality based on the identification and quantification of factors which control the spatial and temporal distribution of biodiversity and productivity in aquatic ecosystems. The context and importance of research into IFEBC is illustrated using case studies from three major areas of research: (i) aquatic habitat quality and restoration ecology, (ii) the genetic and evolutionary potential of aquatic species, and (iii) the detection of stress and toxic effects in aquatic ecosystems using biomarkers. In conclusion, our understanding of the functioning of aquatic ecosystems and conservation management can greatly benefit from the methodological combination of molecular and ecological tools.     

Fish as proxies of ecological and environmental change

Anthropogenic impacts have shifted aquatic ecosystems far from prehistoric baseline states; yet, understanding these impacts is impeded by a lack of available long-term data that realistically reflects the organisms and their habitats prior to human disturbance. Fish are excellent, and largely underused, proxies for elucidating the degree, direction and scale of shifts in aquatic ecosystems. This paper highlights potential sources of qualitative and quantitative data derived from contemporary, archived and ancient fish samples, and then, using key examples, discusses the types of long-term temporal information that can be obtained. This paper identifies future research needs with a focus on the Southern Hemisphere, as baseline shifts are poorly described relative to the Northern Hemisphere. Temporal data sourced from fish can improve our understanding of how aquatic ecosystems have changed, particularly when multiple sources of data are used, enhancing our ability to interpret the current state of aquatic ecosystems and establish effective measures to safeguard against further adverse shifts. The range of biological, ecological and environmental data obtained from fish can be integrated to better define ecosystem baseline states on which to establish policy goals for future conservation and exploitation practices.     

Community genetics: what have we accomplished and where should we be going?

Research in community genetics seeks to understand how the dynamic interplay between ecology and evolution shapes simple and complex communities and ecosystems. A community genetics perspective, however, may not be necessary or informative for all studies and systems. To better understand when and how intraspecific genetic variation and microevolution are important in community and ecosystem ecology, we suggest future research should focus on three areas: (i) determining the relative importance of intraspecific genetic variation compared with other ecological factors in mediating community and ecosystem properties; (ii) understanding the importance of microevolution in shaping ecological dynamics in multi-trophic communities; and (iii) deciphering the phenotypic and associated genetic mechanisms that drive community and ecosystem processes. Here, we identify key areas of research that will increase our understanding of the ecology and evolution of complex communities but that are currently missing in community genetics. We then suggest experiments designed to meet these current gaps.     

Ecological functions of volatile organic compounds in aquatic systems

In terrestrial ecosystems, volatile organic compounds (VOCs) are widely acknowledged as an important group of infochemicals. They play a major role in pollinator attraction by terrestrial plants and as insect pheromones. Furthermore, they are the mediating agent of so-called 'tritrophic interactions'. When plants are attacked by herbivorous insects, volatile signal substances are emitted, which act as attractants for parasitoids that kill the herbivores, thereby protecting the plant from herbivory. Despite the generally acknowledged importance of VOCs in terrestrial chemical ecology, their functions in aquatic food webs are largely unknown. VOCs produced by algae and cyanobacteria are a major concern in water processing, since aquatic primary producers are the reason for regularly encountered taste and odour problems in drinking water. Only very recently, research in aquatic chemical ecology has started to investigate possible ecological functions for the production of VOCs by algae and cyanobacteria. Volatile aldehydes released by wounded cells of marine planktonic diatoms seem to act as defensive compounds against herbivorous copepods on the population level. Just recently, it was found that VOCs released from benthic algae and cyanobacteria can be utilised as food and/or habitat finding cues by aquatic invertebrates such as freshwater gastropods and nematodes. Here, I review concepts and recent experimental studies on the ecological functions of such VOCs in aquatic ecosystems. Understanding the factors that lead to the liberation of volatile compounds is an essential prerequisite to properly assessing their ecological functions. It appears that (similar to terrestrial plant-herbivore interactions) VOCs can also play a steering role for both attraction and defence in aquatic ecosystems.     

Remote sensing for lake research and monitoring – Recent advances

Lakes are important ecosystems providing various ecosystem services. Stressors such as eutrophication or climate change, however, threaten their ecological functions. National and international legislations address these threats and claim consistent, long-term monitoring schemes. Remote sensing data and products provide synoptic, spatio-temporal views and their integration can lead to a better understanding of lake ecology and water quality. Remote sensing therefore gains increasing awareness for analysing water bodies. Various empirical and semi-analytical algorithms exist to derive remote sensing indicators as proxies for climate change or ecological response variables. Nevertheless, most monitoring networks lack an integration of remote sensing data. This review article therefore provides a comprehensive overview how remote sensing can support lake research and monitoring. We focus on remote sensing indicators of lake properties, i.e. water transparency (suspended particulate matter, coloured dissolved organic matter, Secchi disc depth, diffuse attenuation coefficient, turbidity), biota (phytoplankton, cyanobacteria, submerged and emerged aquatic vegetation), bathymetry, water temperature (surface temperature) and ice phenology (ice cover, ice-on, ice-out). After a brief background introducing principles of lake remote sensing we give a review on available sensors and methods. We categorise case studies on remote sensing indicators with respect to lake properties and processes. We discuss existing challenges and benefits of integrating remote sensing into lake monitoring and ecological research including data availability, ready-to-use tools and accuracies.     

Highly unsaturated fatty acids in nature: what we know and what we need to learn

The supply and demand of omega‐3 highly unsaturated fatty acids (ω‐3 HUFA) in natural ecosystems may lead to resource limitation in a diverse array of animal taxa. Here, we review why food quality in terms of ω‐3 HUFAs is important, particularly for neural tissue, across a diversity of animal taxa ranging from invertebrate zooplankton to vertebrates (including humans). Our review is focused on ω‐3 HUFAs rather than other unsaturated fatty acids because these compounds are especially important biochemically, but scarce in nature. We discuss the dichotomy between ω‐3 HUFA availability between aquatic primary producers, which are often rich in these compounds, and terrestrial primary producers, which are contain little to none of them. We describe the use of fatty acids as qualitative and quantitative tracers for reconstructing animal diets in natural ecosystems. Next, we discuss both direct and indirect ecological implications of ω‐3 HUFA limitation at the individual, population, food web, and ecosystem scales, which include: changes in behavior, species composition, secondary production rates, trophic transfer efficiency and cross‐ecosystem subsidies. We finish by highlighting future research priorities including a need for more research on ω‐3 HUFAs in terrestrial systems, more research their importance for higher order consumers, and more research on the food web and ecosystem‐scale effects of ω‐3 HUFA limitation. Synthesis Mismatches between the supply of and demand for omega‐3 highly unsaturated fatty acids (ω‐3 HUFA) in natural ecosystems have the potential to result in resource limitation across a diverse array of ecosystems. We combined perspectives from ecology and nutritional science to develop a unified synthesis of ω‐3 HUFA ecology. We reviewed the importance of ω‐3 HUFAs for animals, the striking differences in ω‐3 HUFA availability at the base of terrestrial versus aquatic food webs, and the implications of ω‐3 HUFA limitation for food webs. We finished by highlighting research priorities in the field including more research on ω‐3 HUFAs in terrestrial systems, on higher order consumers, and at the food web and ecosystem‐scales.     

Salt to conserve: a review on the ecology and preservation of hypersaline ecosystems

When it comes to the investigation of key ecosystems in the world, we often omit salt from the ecological recipe. In fact, despite occupying almost half of the volume of inland waters and providing crucial services to humanity and nature, inland saline ecosystems are often overlooked in discussions regarding the preservation of global aquatic resources of our planet. As a result, our knowledge of the biological and geochemical dynamics shaping these environments remains incomplete and we are hesitant in framing effective protective strategies against the increasing natural and anthropogenic threats faced by such habitats. Hypersaline lakes, water bodies where the concentration of salt exceeds 35 g/l, occur mainly in arid and semiarid areas resulting from hydrological imbalances triggering the accumulation of salts over time. Often considered the ‘exotic siblings’ within the family of inland waters, these ecosystems host some of the most extremophile communities worldwide and provide essential habitats for waterbirds and many other organisms in already water-stressed regions. These systems are often highlighted as natural laboratories, ideal for addressing central ecological questions due to their relatively low complexity and simple food web structures. However, recent studies on the biogeochemical mechanisms framing hypersaline communities have challenged this archetype, arguing that newly discovered highly diverse communities are characterised by specific trophic interactions shaped by high levels of specialisation. The main goal of this review is to explore our current understanding of the ecological dynamics of hypersaline ecosystems by addressing four main research questions: (i) why are hypersaline lakes unique from a biological and geochemical perspective; (ii) which biota inhabit these ecosystems and how have they adapted to the high salt conditions; (iii) how do we protect biodiversity from increasing natural and anthropogenic threats; and (iv) which scientific tools will help us preserve hypersaline ecosystems in the future? First, we focus on the ecological characterisation of hypersaline ecosystems, illustrate hydrogeochemical dynamics regulating such environments, and outline key ecoregions supporting hypersaline systems across the globe. Second, we depict the diversity and functional aspects of key taxa found in hypersaline lakes, from microorganisms to plants, invertebrates, waterbirds and upper trophic levels. Next, we describe ecosystem services and discuss possible conservation guidelines. Finally, we outline how cutting-edge technologies can provide new insights into the study of hypersaline ecology. Overall, this review sheds further light onto these understudied ecosystems, largely unrecognised as important sources of unique biological and functional diversity. We provide perspectives for key future research avenues, and advocate that the conservation of hypersaline lakes should not be taken with ‘a grain of salt’.     

Using ecological networks to answer questions in global biogeography and ecology

Ecological networks have classically been studied at site and landscape scales, yet recent efforts have been made to collate these data into global repositories. This offers an opportunity to integrate and upscale knowledge about ecological interactions from local to global scales to gain enhanced insights from the mechanistic information provided by these data. By drawing on existing research investigating patterns in ecological interactions at continental to global scales, we show how data on ecological networks, collected at appropriate scales, can be used to generate an improved understanding of many aspects of ecology and biogeography—for example, species distribution modelling, restoration ecology and conservation. We argue that by understanding the patterns in the structure and function of ecological networks across scales, it is possible to enhance our understanding of the natural world.     

Endocrine disruption in aquatic systems: up‐scaling research to address ecological consequences

Endocrine‐disrupting chemicals (EDCs) can alter biological function in organisms at environmentally relevant concentrations and are a significant threat to aquatic biodiversity, but there is little understanding of exposure consequences for populations, communities and ecosystems. The pervasive nature of EDCs within aquatic environments and their multiple sub‐lethal effects make assessments of their impact especially important but also highly challenging. Herein, we review the data on EDC effects in aquatic systems focusing on studies assessing populations and ecosystems, and including how biotic and abiotic processes may affect, and be affected by, responses to EDCs. Recent research indicates a significant influence of behavioural responses (e.g. enhancing feeding rates), transgenerational effects and trophic cascades in the ecological consequences of EDC exposure. In addition, interactions between EDCs and other chemical, physical and biological factors generate uncertainty in our understanding of the ecological effects of EDCs within aquatic ecosystems. We illustrate how effect thresholds for EDCs generated from individual‐based experimental bioassays of the types commonly applied using chemical test guidelines [e.g. Organisation for Economic Co‐operation and Development (OECD)] may not necessarily reflect the hazards associated with endocrine disruption. We argue that improved risk assessment for EDCs in aquatic ecosystems urgently requires more ecologically oriented research as well as field‐based assessments at population‐, community‐ and food‐web levels.     

The ecology of information: an overview on the ecological significance of making informed decisions

Information is characterized as the reduction of uncertainty and by a change in the state of a receiving organism. Thus, organisms can acquire information about their environment that reduces uncertainty and increases their likelihood of choosing a best‐matching strategy. We define the ecology of information as the study of how organisms acquire and use information in decision‐making and its significance for populations, communities, landscapes and ecosystems. As a whole, it encompasses the reception and processing of information, decision‐making, and the ecological consequences of making informed decisions. The first two stages constitute the domains of, e.g. sensory ecology and behavioral ecology. The exploration of the consequences of information use at larger spatial and temporal scales in ecology has lagged behind these other disciplines. In our overview we characterize information, discuss statistical decision theory as a quantitative framework to analyze information and decision‐making, and discuss potential ecological ramifications. Rather than attempt a cursory review of the enormity of the scope of information we highlight information use in development, breeding habitat selection, and interceptive eavesdropping on alarm calls. Through these topics we discuss specific examples of ecological information use and the emerging ecological consequences. We emphasize recurring themes: information is collected from multiple sources, over varying temporal and spatial scales, and in many cases links heterospecifics to one another. We conclude by breaking from specific ecological contexts to explore implications of information as a central organizing principle, including: information webs, information as a component of the niche concept, and information as an ecosystem process. With information having such an enormous reach in ecology we further cast a spotlight on the potential harmful effects of anthropogenic noise and info‐disruption.     

The ecology of chytrids in aquatic ecosystems: roles in food web dynamics

Chytrids are very important components of freshwater ecosystems, but the ecological significance of this group of fungi is not well understood. This review considers some of the significant environmental factors affecting growth and population composition of chytrids in aquatic habitats. The physical factors include primarily salinity, dissolved oxygen concentration and temperature. The biological factors include the role of chytrids as saprobes and parasites and methods of dispersal of propagules throughout the ecosystem. Dispersal depends upon both zoospores for short range and whole thalli for long range dispersal. Five roles for chytrids in food-web dynamics are proposed: (1) chytrid zoospores are a good food source for zooplankton, (2) chytrids decompose particulate organic matter, (3) chytrids are parasites of aquatic plants, (4) chytrids are parasites of aquatic animals and (5) chytrids convert inorganic compounds into organic compounds. New molecular methods for analysis of chytrid diversity in aquatic environments have the potential to provide accurate quantitative data necessary for better understanding of ecological processes in aquatic ecosystems.     

溪流粗木质残体的生态学研究进展

粗木质残体（CWD）是森林或溪流生态系统中残存的超过一定直径大小的站杆、倒木、枝桠及根系等死木质物的总称,溪流CWD对于溪流生态系统的稳定,水生生物多样性,河槽形态及其变化过程有着重要的作用。对溪流CWD的产生和分类,溪流CWD对于溪流生态系统的稳定,水生生物多样性,河槽形态及其变化过程有着重要的作用。对溪流CWD的产生和分类,溪流CWD贮量,分布和动态,以及溪流CWD的功能和管理分别进行了总结,并指出应尽快在国内开展溪流CWD的研究和管理。     

Functional Diversity as a New Framework for Understanding the Ecology of an Emerging Generalist Pathogen

Emerging infectious disease outbreaks are increasingly suspected to be a consequence of human pressures exerted on natural ecosystems. Previously, host taxonomic communities have been used as indicators of infectious disease emergence, and the loss of their diversity has been implicated as a driver of increased presence. The mechanistic details in how such pathogen–host systems function, however, may not always be explained by taxonomic variation or loss. Here we used machine learning and methods based on Gower’s dissimilarity to quantify metrics of invertebrate functional diversity, in addition to functional groups and their taxonomic diversity at sites endemic and non-endemic for the model generalist pathogen Mycobacterium ulcerans, the causative agent of Buruli ulcer. Changes in these metrics allowed the rapid categorisation of the ecological niche of the mycobacterium’s hosts and the ability to relate specific host traits to its presence in aquatic ecosystems. We found that taxonomic diversity of hosts and overall functional diversity loss and evenness had no bearing on the mycobacterium’s presence, or whether the site was in an endemic area. These findings, however, provide strong evidence that generalist environmentally persistent bacteria such as M. ulcerans can be associated with specific functional traits rather than taxonomic groups of organisms, increasing our understanding of emerging disease ecology and origin.