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Over the last two decades, there has been increasing public and political recognition of society's dependency upon natural habitat complexity and ecological processes to sustain provision of crucial ecosystem services, ranging from supplying potable water through to climate regulation. How has the ecosystem-services perspective been integrated into strategies for aquatic habitat conservation? Literature on conservation of diverse freshwater and marine habitats was reviewed to assess the extent to which past and current strategies specifically targeted ecosystem services, and considered ecosystem functions, potential trade-offs and social issues when formulating protection measures for conserving aquatic habitats. Surprisingly few published examples exist where comprehensive assessment of ecosystem services supported development of conservation plans. Seldom were aquatic habitat conservation objectives framed in terms of balancing trade-offs, assessing social values and evaluating suites of ecosystem services under different strategies. Time frames for achieving these objectives were also rarely specified. There was no evidence for fundamental differences between marine and freshwater habitats with respect to their ecosystem services that should be considered when setting targets for their conservation. When an ecosystem-service perspective is used for setting objectives in aquatic habitat conservation, the following actions are recommended: (1) explicitly listing and evaluating full suites of ecosystem services to be conserved; (2) identifying current and future potential trade-offs arising from conservation; (3) specifying time frames within which particular strategies might protect or enhance desired services; and (4) predicting how different proposed strategies might affect each ecosystem function, service flow and public benefit. This approach will help ensure that less-apparent ecosystem services (e.g. regulating, supporting) and their associated ecosystem functions receive adequate recognition and protection in aquatic conservation of freshwater and marine habitats. However, conservation objectives should not focus solely on protecting or enhancing ecosystem services but complement current strategies targeting biodiversity and other conservation goals. ; Peer Reviewed

Stream ecosystem metabolism plays a critical role in planetary biogeochemical cycling. Stream benthic habitat complexity and the available surface area for microbes relative to the free-flowing water volume are thought to be important determinants of ecosystem metabolism. Unfortunately, the engineered deepening and straightening of streams for drainage purposes could compromise stream natural services. Stream channel complexity may be quantitatively expressed with hydraulic parameters such as water transient storage, storage residence time, and water spiralling length. The temperature dependence of whole stream ecosystem respiration (ER), gross primary productivity (GPP) and net ecosystem production (NEP = GPP−ER) has recently been evaluated with a "natural experiment" in Icelandic geothermal streams along a 5−25 ◦C temperature gradient. There remained, however, a substantial amount of unexplained variability in the statistical models, which may be explained by hydraulic parameters found to be unrelated to temperature. We also specifically tested the additional and predicted synergistic effects of water transient storage and temperature on ER, using novel, more accurate, methods. Both ER and GPP were highly related to water transient storage (or water spiralling length) but not to the storage residence time. While there was an additional effect of water transient storage and temperature on ER (r2 = 0.57; P = 0.015), GPP was more related to water transient storage than temperature. The predicted synergistic effect could not be confirmed, most likely due to data limitation. Our interpretation, based on causal statistical modelling, is that the metabolic balance of streams (NEP) was primarily determined by the temperature dependence of respiration. Further field and experimental work is required to test the predicted synergistic effect on ER. Meanwhile, since higher metabolic activities allow for higher pollutant degradation or uptake, river restoration and management should promote habitat diversity and complexity (hyporheic zone, macrophyte patches, substrate heterogeneity), especially for microbial activity. ; Le métabolisme des écosystèmes aquatiques fluviaux joue un rôle critique dans les cycles biogéochimiques planétaires. La complexité des habitats benthiques et l'aire disponible pour les microbes par rapport au volume d'eau qui s'écoule sont considérées comme des facteurs importants pour le métabolisme de l'écosystème. Malheureusement, le creusement et l'alignement des cours d'eau pour le drainage des terres pourraient compromettre les services naturels fournis par les cours d'eau. Cette complexité peut être exprimée quantitativement avec des paramètres hydrauliques tels que le stokage transitoire de l'eau dans le lit de la rivière, la durée de résidence du stockage transitoire, et la longueur du flux en hélice (ou spirale) de l'eau (distance moyenne parcourue par une molécule d'eau dans la zone d'eau courante libre avant d'entrer dans la zone calme). L'effet de la température sur la respiration globale des ruisseaux (ER), productivité primaire brute (GPP) et production nette de l'écosystème (NEP) a récemment été évalué au travers d'une « expérience naturelle » dans des ruisseaux géothermiques islandais le long d'un gradient de température de 5−25 ◦C. Il resta, cependant, une quantité substantielle de variabilité non expliquée par les modèles statistiques, qui pourrait être expliquée par les paramètres hydrauliques non reliés à la température. Nous avons aussi tout particulièrement testé les effets additionnels et en synergie du stokage transitoire de l'eau et de la température sur la respiration, en utilisant de nouvelles méthodes. ER and GPP furent hautement corrélées au stockage transitoire de l'eau (ou flux en hélice de l'eau), mais pas à la durée de résidence du stockage. Le stokage transitoire de l'eau et de la température eurent un effect additionnel sur ER (r2 = 0,57 ; P = 0,015), en revanche GPP était plus liée au stockage transitoire de l'eau qu'à la température. L'effet en synergie ne put être confirmé, probablement dû aux limitations des données. Notre interpretation, basée sur un modèle statistique causal, est que l'équilibre métabolique des cours d'eau (NEP) était principalement contrainte par la réponse de la respiration à la température. D'autres travaux de terrain et expérimentaux sont nécessaires pour tester notre nouvelle hypothèse d'un effet en synergie sur ER. Dans l'attente, puisqu'une plus haute activité métabolique permet une rétention ou dégradation plus importante des polluants, la restoration et la gestion des cours d'eau devraient promouvoir la diversité et la complexité des habitats (hyporhéos, touffes de macrophytes, hété- rogénéité du substrat) particulièrement pour l'activité microbienne. ; This study was funded by the Scottish Government Rural and Environment Research and Analysis Directorate (RERAD), now Rural and Environment Science and Analytical Services (RESAS). J.R.M. acknowledges the support of the Richard Stockton College of New Jersey. We would like to thank Tryggvi Thordarson, director of the Research Station at Hveragerdi for lodging and his warm hospitality, Marc Stutter and two anonymous referees for their insightful comments on the manuscript. ; Peer Reviewed ; Ritrýnt tímarit

Global warming is widely predicted to reduce the biomass production of top predators, or even result in species loss.Several exceptions to this expectation have been identified, however, and it is vital that we understand the underlyingmechanisms if we are to improve our ability to predict future trends. Here, we used a natural warming experiment inIceland and quantitative theoretical predictions to investigate the success of brown trout as top predators across astream temperature gradient (4–25 °C). Brown trout are at the northern limit of their geographic distribution in thissystem, with ambient stream temperatures below their optimum for maximal growth, and above it in the warmeststreams. A five-month mark-recapture study revealed that population abundance, biomass, growth rate, and produc-tion of trout all increased with stream temperature. We identified two mechanisms that contributed to theseresponses: (1) trout became more selective in their diet as stream temperature increased, feeding higher in the foodweb and increasing in trophic position; and (2) trophic transfer through the food web was more efficient in the war-mer streams. We found little evidence to support a third potential mechanism: that external subsidies would play amore important role in the diet of trout with increasing stream temperature. Resource availability was also amplifiedthrough the trophic levels with warming, as predicted by metabolic theory in nutrient-replete systems. These resultshighlight circumstances in which top predators can thrive in warmer environments and contribute to our knowledgeof warming impacts on natural communities and ecosystem functioning. ; The authors are supported by grants awarded by NERC (NE/L011840/1 and NE/I009280/2), the Royal Society (RG140601), the British Ecological Society (4009-4884), the Fisheries Society of the British Isles, the Grand Challenges in Ecosystems and the Environment initiative at Imperial College London, the Scottish Government Rural and Environment Science and Analytical Services (RESAS), the Salmonid Fisheries Management Fund in Reykjavik, and Assistantship and Research Funds from the University of Iceland (GMG2006, GMG2007). ; Peer Reviewed ; Ritrýnt tímarit

Global change threatens invertebrate biodiversity and its central role in numerous ecosystem functions and services. Functional trait analyses have been advocated to uncover global mechanisms behind biodiversity responses to environmental change, but the application of this approach for invertebrates is underdeveloped relative to other organism groups. From an evaluation of 363 records comprising >1.23 million invertebrates collected from rivers across nine biogeographic regions on three continents, consistent responses of community trait composition and diversity to replicated gradients of reduced glacier cover are demonstrated. After accounting for a systematic regional effect of latitude, the processes shaping river invertebrate functional diversity are globally consistent. Analyses nested within individual regions identified an increase in functional diversity as glacier cover decreases. Community assembly models demonstrated that dispersal limitation was the dominant process underlying these patterns, although environmental filtering was also evident in highly glacierized basins. These findings indicate that predictable mechanisms govern river invertebrate community responses to decreasing glacier cover globally. ; This work was funded by the following organisations: The UK Natural Environment Research Council grants and studentships GR9/2913, NE/E003729/1, NE/E004539/1, NE/E004148/1, 20 NE/G523963/1, NER/S/A/2003/11192, and NE/L002574/1; the European Union Environment and Climate Programme Arctic and Alpine Stream Ecosystem Research (AASER) project (ENV-CT95-0164); EU-FP7 Assessing Climate impacts on the Quality and quantity of WAter (ACQWA) project (212250); Icelandic Research Council (954890095, 954890096); University of Iceland Research Fund (GMG96, GMG97, GMG98), Wyoming Center for Environmental Hydrology and Geophysics-National Science Foundation (1208909); USA-Wyoming NASA Space Grant Faculty Research Initiation (#NNX10A095H); USA-NSF Wyoming Epscor; Nationalpark Hohe Tauern, Austria; the Royal Society (International Outgoing Grant 2006/R4); the Leverhulme Trust; the Universities of Leeds, Birmingham, Iceland and Innsbruck; European Centre for Arctic Environmental Research (ARCFAC): a Research Infrastructures Action of the European Community FP6 (026129-2008- 72); the Stelvio National Park (2000-2001); the Autonomous Province of Trento (HIGHEST project, 2001-2004, del. PAT n. 1060/2001; VETTA project, 2003-2006, del. PAT n. 3402/2002); MUSE-Museo delle Scienze. We are grateful to Russell Taylor and Mike Winterbourn at the University of Canterbury, NZ, who helped to collect NZ invertebrate data and assisted with identification, and to Hakon Adalsteinsson who contributed to data collection in Iceland. Many other people, too numerous to mention, assisted with fieldwork at all of the study locations. The European Science Foundation sponsored an exploratory ┘ラヴニゲエラヮ WミデキデノWS さGノ;IキWヴ-fed rivers, hydroecology and climate change: current knowledge and future network of monitoring sites (GLAC-HYDROECO-NETぶざ デエ;デ ┘;ゲ エWノS キミ Birmingham, UK in September of 2013 where some of the ideas in this paper were first discussed ; Peer Reviewed