Freshwater Biology Special Issues

Freshwater Biology publishes 2-3 special themed issues each year which are available at the special single-issue price of £25.00 each. To order any of the following Freshwater Biology special issues please contact Customer Services .

Ecological stoichiometry of freshwater benthic ecosystems

FWB 50(11), November 2005
Guest Editors: Wyatt F. Cross, Jonathan P. Benstead, Paul C. Frost

Ecological stoichiometry provides a conceptual framework that considers how the balance of key elements (e.g. carbon, nitrogen, phosphorus) affects and is affected by organisms in the environment. This framework has increased mechanistic understanding of a wide range of ecological topics, including population dynamics, trophic interactions, and nutrient cycling. While most theoretical and empirical research on ecological stoichiometry has been conducted in freshwater pelagic ecosystems, the papers in this issue apply stoichiometric concepts to a diversity of freshwater benthic systems. A key emergent theme from this issue is that benthic basal resources in lakes, streams and rivers comprise an extremely wide range of potential food quality for consumers (ranging from nutrient-rich algae and bacteria to nutrient-poor wood and leaf litter), and this range is generally much larger than that found in pelagic habitats. Consequently, many trophic interactions and organic matter transformations in benthic systems are likely to be constrained, to some degree, by stoichiometric imbalances. These consumer-resource elemental imbalances in turn may have significant ecosystem-wide consequences.

TopLake oligotrophication

FWB Special Issue 50(10), October 2005
Guest Editors: N.J. Anderson, E. Jeppesen, M. Søndergaard & R.W. Battarbee

Many lakes are presently experiencing declining nutrient concentrations. These declines can be tracked by direct chemical measurements which provide are high-precision and high-resolution data but are limited to the last few decades at best. Palaeolimnological methods are coarser but they can often extend the time window tremendously, thus potentially giving access to information on lake trophic status hundreds of years ago or more, before lakes were noticeably affected by humans. The composite image on the journal cover (Photo credit: Martin Dokulil) shows trends in total phosphorus derived from both monitoring data (solid black line) and palaeolimnological data (dash line) for Mondsee, an Austrian lake that has undergone oligotrophication over recent decades. See Vol.50; Page: 1594 of Freshwater Biology for this article.

TopFish and Nutrient effects in shallow lakes: A Pan-European Mesocosm Experiment

Special Issue 49 (12), December 2004
This special includes ten papers, all from a major experiment carried out in lakes in Finland , Sweden , the UK , the Netherlands and Spain . Called 'Fish and Nutrient Effects in Shallow Lakes : a Pan-European Mesocosm Experiment, it shows how the effects of fish and nutrient additions change on a gradient from north to south. A major finding was that the results of the same experiment can differ from year to year in the same place and that this unpredictability is greater, the lower the temperature or the higher the latitude. The experiment also showed that the effects of nutrients were stronger with decreasing latitude. The experiment contributes to understanding of lake biology in general, has implications for the need to repeat experiments and for managing shallow water lakes under such new legislation as the Water Framework Directive.

TopBiomanipulation of Lake Ecosystems

FWB 48(7), July 2003
The Role of Drought in the Ecology of Aquatic Ecosystems
Guest editors: P. Humphries and D. S. Baldwin
Extreme hydrologic conditions can profoundly affect aquatic ecosystems. Papers in this special issue are devoted to the impact of drought on the organisms of, and abiotic processes in, freshwaters, particularly in streams and rivers. Defining drought hydrologically is problematic, because the return times, duration and long-term trends of low-flow periods are specific to regions and times; instead it has been suggested to refer to droughts as significant low flow periods'. Droughts can be divided into those that are predictable and seasonal' (press disturbances) and those that are less predictable and supra-seasonal' (ramp disturbance). While supra-seasonal droughts may be ramped, the effects on aquatic organisms are most likely stepped', as geomorphological or hydrological thresholds are reached. Therefore, the role of refugia for conveying resistance or resilience to populations and communities must be considered when assessing the effects of drought on stream ecosystems. Predicting supra-seasonal droughts in advance is difficult (one has to be in a drought before one can recognise it as such), as is the identification of effects over large temporal (decades to centuries) and spatial (river basins to sub-continents) scales. However, as an extreme example, a genetic study of a riverine fish presented in this issue suggests that a post-Pleistocene drought caused a population bottleneck that altered the course of the species' evolution. An ethos of promoting hydrologic constancy leading for example to successful breeding of aquatic birds every year or consistently large populations of legal-sized fish still pervades much of the conservation debate and natural resource management. The idea is embodied so much that events like drought and the devastation' that they cause are often seen as antipathetic to good management. This view does not do justice to the potential significance of drought for shaping and maintaining aquatic communities and ecosystems. The papers in this issue challenge this ethos.

TopSpecial Section: Invasive Species in Freshwaters: Impacts and Distributions

FWB 48(6), June 2003
Guest Editors: D. O'Dowd and P.S. Lake
Biological invasions have emerged as a key driver of change in freshwaters, decreasing biodiversity and disrupting ecosystem functions. A series of papers in the June 2003 issue of Freshwater Biology addresses major transitions in the invasion process, a better understanding of which is essential for sustainable management of freshwaters. Studies of on-going freshwater invasions, combining phylogenetic and biogeographic analyses with field surveys, can be used to identify source areas and transport pathways, a key to the prevention of future unwanted introductions. Once an invader has established, analyses of habitat variables (e.g. streamflow variability or riparian disturbance) in invaded and uninvaded areas can help predict its future success and distribution. Comparative and experimental analyses continue to increase our understanding of the complexity of impacts following invasions. Detailed, quantitative information of the invasion history of a species can guide predictions of consequences following introduction into new environments. Such information is rarely available, however, limiting this approach. Impacts of aquatic invaders may be counterintuitive and not readily foreseen through descriptive study alone. Although often examined at the population level, impacts of invaders may ripple across levels of ecological organization, disrupting communities and ecosystem processes, and sometimes generating unintended and unwelcome surprises.

TopResearch Progress, Water Quality and Fisheries Management

FWB 47(12), December 2002
Guest editors: P. Kasprzak, J. Benndorf, T. Mehner and R. Koschel
Biomanipulation research has substantially contributed to progress in understanding complex lake food webs. To illustrate advances made during the last decade, this special issue addresses three main topics: (1) mechanisms involved in biomanipulation, (2) whole-lake case studies, and (3) management aspects in water quality and fisheries. The higher success rates of biomanipulation in shallow as opposed to stratified lakes can be attributed to positive feedback mechanisms relating to the recovery of submerged macrophytes. The role of both nutrient loading and in-lake concentrations in predicting the success of biomanipulations is emphasized and supported by empirically defined threshold values. Ontogenetic niche shifts and size-structured interactions, particularly of fish populations, add to the complexity of lake food webs and make scientifically sound predictions of biomanipulation success more difficult than was previously envisaged. An appropriate balance between piscivorous, planktivorous and benthivorous fishes is required for long-lasting success of biomanipulations. Recommended proportions and densities of piscivorous fish are currently based on data from only a few biomanipulation experiments and need to be corroborated by quantitative assessments of energy flow through lake food webs. Biomanipulation effects in stratified lakes can be sustained in the long-term only by continued interventions. Biomanipulation is increasingly used as lake restoration technique by considering the needs of all lake users. The combination of water quality management and fisheries management for piscivores with positive effects for both appears to be particularly promising.

TopRiverine Landscapes

FWB 47(4), April 2002
Guest editors: K. Tockner, J. V. Ward, J. Kollmann & P.J. Edwards
Landscape ecology deals with the influence of spatial pattern on ecological processes. Traditionally, landscape ecologists have focused on terrestrial ecosystems, and rivers and streams have been considered as uniform elements within this terrestrial mosaic. In this special issue on Riverine Landscapes, we extended the principles and approaches of landscape ecology by to riverine ecosystems. The papers in this issue demonstrate that placing the major recent developments in river ecology within a dynamic landscape context can provide new insights into the structural and functional attributes of these systems. Furthermore, rivers and streams provide excellent opportunities for advancing and testing general theory in landscape ecology. The primary goal of this special issue was to synthesize our present understanding of the complexity and dynamics of riverine landscapes by integrating different disciplines, including aquatic and terrestrial ecology, geomorphology and palaeohydrology, with landscape ecology. The current state of research on riverine landscapes is reviewed and future research directions are given in a total of 22 articles. Several papers focus on how our current knowledge about riverine landscapes can be applied to schemes for restoring impacted riverine systems. To meet this objective, landscape metrics most useful for monitoring population, community and ecosystem processes in river-floodplains and whole river-catchments are identified.