This paper describes the establishment of a strategic programme of physical restoration on a series of English rivers with special protection status. Over a period of 10 years, decision-making processes have been developed to encourage long-term and ambitious thinking in tackling the damaging modifications that have affected these rivers. The programme is based on natural ecosystem function generated by natural riverine processes. The decision–making process aims to tackle practical constraints to more natural river function and generate strategic plans around which available resources can be harnessed in a coordinated and logical fashion, in partnership with local stakeholders and landowners. The programme has been successful in developing strategic plans for most specially protected rivers in England, and practical implementation of measures is well underway and increasing each year. The process has been valuable in providing a basis for bids to a range of domestic and European funds, and for drawing local stakeholders together within a common delivery framework. Over time, more local stakeholder resources are becoming available as the benefits of restored natural ecosystem function are becoming more apparent. The physical modifications affecting these rivers reflect the impacts on the wider river network in England and in other developed countries. The lessons learnt from this programme over the past ten years will be of use to those working on river restoration elsewhere in England, the UK, Europe and further afield. Whilst the current global economic outlook for funding is bleak, the processes established in England allow available resources to be harnessed and used in the most efficient way possible. This will be important for river restoration initiatives wherever they are attempted and for whatever purpose.

‘The history of streams and rivers is as much a social and technological history as it is a scientific one.’ (Petts, 2001)‘Too often, imperfect analyses combine with conflicting socio-economic interests and politics to limit rehabilitation success.’ (Booth et al., 2004)‘Restoring the river costs money, lots of it. Critics argue that we can't afford to restore a river for a few endangered fish or birds.’ Public statement about the Missouri restoration work, quoted by Marain Maas in a lecture to the Water Protection Network, 18–20 March 2012.In industrialised countries over the last sixty years a combination of new laws, technological advances, scientific developments, commercial and economical changes, and public and political opinion has resulted in the chemical and ecological recovery of many rivers that have been polluted over centuries. Improvements to water quality have been directly and positively linked — through both experimentation and the long-term monitoring of chemical and ecological conditions — to ecological enhancement, usually measured in terms of taxon richness or community diversity and expressed as readily interpretable indices.Ecological enhancement has often been used as the major reasoning behind efforts to restore rivers to their natural hydro-geomorphic (geographical, geological and hydrological) condition, based on the hypothesis that increasing hydro-geomorphic diversity in river catchments and floodplains will in turn increase the natural diversity of living organisms. However, direct studies and metadata analyses demonstrate that any relationship between physical restoration and ecological indicators is at best uncertain and at worst neither quantified nor readily quantifiable, and even the physical results of such restoration projects have not always met expectations, with many schemes failing for various reasons.In this article we propose that it is not the potential improvements to the ecology or the physical characteristics of the rivers (hydromorphology) that has been of primary importance when deciding to carry out restoration projects; instead it is a drive by the global finance industry to deliver flood alleviation schemes and thus save huge compensation payments, and political expediency where public opinion has reacted strongly against flooding. Evidence includes the continued planning of such projects under the guise of ecological improvements, even in the light of the clear physical and ecological failures of many completed river restorations. Since the success or failure of such proposals is measured often by public attitudes and subjective opinions, ecological consequences are often not measured. However, advances in science and the involvement of ecologists with distinguished careers and high integrity may have provided scientific gravitas to facilitate acceptance of the plans.We also explore some of the unintended commercial and social consequences of pollution controls in the UK during the 1960s, including accelerated industrial emigration, which in turn had significant and predictable repercussions in developing countries such as China and India. The effects these consequences will have on future restorations and pollution controls are considered, as well as potential international social, political, commercial and economic requirements particularly in newer and future industrialised countries.

Lake sediments are natural archives that record the response of a lake to both in-lake processes and catchment disturbance (over a range of timescales). The response (or lack of) of a lake to external forcing is a function of the severity of the disturbance (and its areal extent) but is also strongly mediated by catchment characteristics, such as slope and hydrological connectivity. Many studies of recent lake disturbance have focussed on anthropogenic disruption of geochemical cycles, e.g. acidification and eutrophication, which because of their “ecological” power appear to over-ride catchment filters. Lake sediments also record the variability of natural disturbance regimes themselves (fire, volcanic ash falls, species invasions, and climate) and the consequent lake response but this aspect has received much less attention. The possibility of using lake sediments to address long-term (102 – 103 yr) interactions between e.g., climate, catchment ontogeny and disturbance events (and their synergies) has not been fully explored, largely because of an over-riding emphasis on climate as a direct driver of ecological change.Traditionally, limnology has also focussed on a few key sites (sentinels) but in response to the development of landscape ecology has progressively embraced a regional approach to understanding how lakes respond to external forcing (climate) and disturbance (“lakes in the landscape”). Although the interaction of a lake with its catchment is implicit, i.e. via hydrological and nutrient loading, palaeolimnologists rarely take an explicitly spatial view of this interaction nor have they considered spatial location (i.e. response of a number of lakes within a lake district). Arguably, the inherent spatial variability of terrestrial disturbance has been ignored by palaeolimnologists, largely as a result of focussing on one core from a single lake.This paper reviews the impact of terrestrial disturbance on lakes but also argues for explicit consideration of space and location in determining the resultant temporal variability of the ecological response. The importance of within-lake spatial heterogeneity is also high-lighted (i.e. the major contribution of the littoral zone to both diversity and production). However, any attempt to determine spatially replicated (i.e. at a regional scale), holistic (i.e. whole lake) responses to disturbance will encounter considerable problems associated with dating, loss of temporal resolution and among site comparison. Despite this, it is clear that recent methodological developments in the area of biomarkers, compound specific stable isotopes coupled with progress in dating (age-models), ecological modelling and statistical analysis offer the possibility of undertaking regionally-replicated studies of lake response to natural disturbance, thereby contributing and expanding our understanding of ecosystem dynamics at a range of spatial and temporal scales.

The literature on ecological effects of recent climate change in fresh waters has been reviewed, with particular reference to freshwater conservation in the UK. Least emphasis is given to predictive models of future change, because of considerable uncertainties even in the climate models, let alone their biological implications. Climate change effects on fresh waters have been superimposed on existing large human impacts, which make separation of climatic effects particularly difficult.Research in fresh waters has concentrated on communities and processes and there is less emphasis on individual charismatic species than in terrestrial systems. This approach lends itself to space-for-time studies on climate effects. There has been a modest amount of experimentation, particularly in mesocosms, and analysis of long-term biological data sets, the most extensive from lakes. The most detailed information on ecological effects comes from lake plankton.No species is yet known to have been lost from the UK as a result of climate change but there is extensive evidence of changes in phenology and distribution, and in processes in the plankton. It is likely that temperature effects per se will be less important than effects of changed hydrology and that idiosyncratic behaviour of each species will lead to many indirect effects through biological interactions in communities. Experimental studies suggest major likely changes in plant, fish and invertebrate communities with a several degree increase in temperature and associated hydrological changes expected in the 21st century. Freshwater organisms, however, are well adapted to disturbance and through invasion, redistribution, adaptation and microevolution will re-form functioning communities, though with likely different biodiversity than at present. Some invasive species may come to dominate the new communities. There will be important consequences for the estimation of ecological quality, which will inconvenience statutory obligations under the Water Framework Directive, and symptoms of eutrophication will be exacerbated. Some coastal lakes may revert to estuaries.Much more important, however, may be the consequences of climate change for the important part of the carbon cycle that is focussed on fresh waters, particularly if the ratio of community respiration to gross primary production increases with rising temperature. Several studies suggest large increases in this ratio with temperature rises of up to 4 °C. A much more radical approach to conservation, involving re-establishment of entire, connected catchment systems rather than the present piecemeal attention to biodiversity issues is likely to be needed if a comfortable human future is to be guaranteed.

Abstract Carbon cycling is a cornerstone concept of ecosystem ecology, which has implications for climate change, ecosystem health, and human activities. This review investigates pathways of carbon within freshwater ecosystems, the role of terrestrial carbon in food webs, and the effects of food web structure on C emissions. Carbon may co-limit primary production even in waters super-saturated with CO2. Allochthonous carbon-subsidies make most lakes and rivers net heterotrophic; however, the use of carbon-subsidies by the food web (FW) may be limited by low nutritional quality of terrestrial C-compounds and the inability of bacteria to synthesise polyunsaturated fatty acids (PUFA), which are essential for metazoan growth. Bacterivorous nanoflagellates which can synthesise PUFA are likely to create a channel connecting allochthonous C with metazoan production in some water bodies. Published studies suggest that FW structure may affect: carbon fluxes in and out of lake ecosystems; carbon accumulation and distribution within food webs; burial of carbon and carbon sequestration. Food web structure and nutrients can affect the carbon-emission/sequestration ratio and shift the state of the aquatic ecosystem between being a source or a sink for atmospheric carbon. Small lakes, such as farm ponds, are the dominant type of world fresh waters with highest carbon burial rates. Their productivity and FW structure are often modified by humans through nutrient fertilisation and fisheries management. We hypothesise that the planned management of these activities targeting a desirable emission/sequestration ratio, can be used as a tool for the reduction of carbon emissions to the atmosphere.

Eutrophication remains one of the foremost environmental issues threatening the quality of surface waters yet comparatively little is known of the timing, magnitude and characteristics of nutrient-related changes in highly calcareous (marl) lakes. This review focuses on marl lake ecology and chemistry, their known responses to eutrophication, and also highlights questions that remain unanswered.In good condition, marl lakes support a diversity of macrophytes, especially Characeae and Potamogetonaceae, which can grow to considerable depth. High water transparency and low phosphorus and phytoplankton concentrations are facilitated by the coprecipitation of marl and phosphorus. Although large amounts of phosphorus can be thus removed, buffering against eutrophication, macrophyte communities can undergo significant change under rather low nutrient concentrations. Maximum colonisation depth declines and tolerant species replace sensitive species, with losses particularly among charophytes. Marl lakes are therefore ecologically highly sensitive.The effects of coprecipitation on long-term burial of phosphorus are contested. Several palaeolimnological studies have identified iron complexes as more important than calcite, as chemical conditions in the sediment may promote either calcite dissolution or calcite-bound phosphorus exchange, or possibly both. Some marl lakes have been shown to have phosphorus concentrations which, compared with other lake types, are higher than expected in winter and lower in summer. The phosphorus binding capacity of marl sediment has not to our knowledge been adequately researched.Marl precipitation may be inhibited by high phosphate or organic matter concentrations in the water, or when biological communities effecting precipitation (picoplankton, charophytes, epiphytes) are disturbed. Highly impacted marl lakes having low species diversity and lacking precipitation may be misidentified as eutrophic, high-alkalinity lakes. More studies addressing the interaction between external loading, phosphorus cycling and marl precipitation in relation to biological communities are required to assess to what extent marl lakes can buffer eutrophication, and what factors contribute to disturbed marl precipitation.

Lobo/Broa reservoir research was established in 1971 as a model of limnological and ecological research in aquatic ecosystems in Brazil. The present paper describes the ecological dynamics of the reservoir, the climatological and hydrological interactions, limnological factors and the responses of the aquatic biota to the forcing functions mainly of precipitation and wind. It also emphasises management issues and technologies, and processes developed to control eutrophication. Ecosystem services are described.