Search

Invasion rates are increasing worldwide and most are due to the actions of humans. Deliberate introductions, escapes, and hitchhiking with global commerce transport species to other continents. While most species fail to thrive or have minor impacts on their new ecosystems, the large number of introductions has led to numerous problems. Aquatic invasive species are particularly pervasive and may cause food web disruption, biodiversity loss, and economic harm. Biological invasions appear in an increasing number of publications in the aquatic and general ecology literature. This special issue of Hydrobiologia includes 31 papers on aquatic invasive species and the factors that influence their dispersal and success, along with their impacts. Ecosystems include freshwater ponds, lakes and reservoirs, small streams and large rivers, and coastal marine systems. Study regions occur in temperate, as well as less-studied tropical and sub-tropical regions of four different continents. We discuss the dynamics of invasive species research in the current literature and provide a brief overview of the contributions to this issue. [ABSTRACT FROM AUTHOR]

A preface to the journal "Hydrobiologia" is presented.

The recent decline in taxonomic studies is well recognized. Algae-related papers (390) published in five leading limnology journals (1971–2004) were consulted to assess similar trends in limnology by taking algae as a test aquatic group. The study showed a decrease of algae-only studies and an increase of multi-group studies (algae plus one or more aquatic groups). Identification of species decreased while mentioning of ecological groups (phytoplankton, epiphytes, etc.) increased while presenting results. Species identification, however, was not associated with number of aquatic groups or number of algal species included in a study. Problems probably lie with the old-fashioned image of taxonomy and it being threatened by the recent advancement in evolutionary and molecular biology. Issues like the changing research patterns in freshwater ecology, scope of limnological works, its workers and relevant journals are also shaping the status of traditional taxonomy in limnology. Practices such as giving of at least (algal) genera in community studies, and of the current names of studied species in physiological/molecular works and also in studies on particular supra-generic taxa (Class, Family, etc.), could help sustaining of taxonomy in limnology. [ABSTRACT FROM AUTHOR]

Surface area measurement is a common component of benthic research, especially in the quantification of chlorophyll. Multiple techniques are available and 10 are described: artificial substrates, area-specific sampling, geometric approximation, stone shape equations, foil wrapping, grids, stamps, wetted layer, particle layer, and planar area measurement. A literature search of 130 papers indicated the most common methods: using artificial substrates of known area, subsampling a specific area using a template or sampler, measuring stone dimensions and using an equation to derive area, and using the weight of foil wrapped on stones. Methods were compared using spheres of known area, smooth and rough granite stones, and plastic macrophytes. Most methods produced highly correlated measurements and accurately estimated surface area. The wetted layer method was sensitive to stone roughness and plant complexity, but may overestimate the area of complex surfaces. Replication of one method by 10 biologists indicated that individual differences in technique can affect surface area values. Factors to consider in choosing an appropriate method include ease of use, characteristics of the substrates (e.g., porosity and flexibility), fineness of scale in measuring area, and whether methods must be field-based or can include laboratory techniques. [ABSTRACT FROM AUTHOR]

Presents several books related to hydrobiologia.

Presents the preface to the July 2003 issue of "Hydrobiologia."

Ichthyofauna in the littoral zone the southern extremity of Lake Baikal was investigated. Modern data were obtained on fish composition in waters most affected by anthropogenic factors, where the probability of resultant changes in the fish community is highest. Long-term fish sampling was carried out in the zone of discharge and spread of wastes from Baikal Pulp and Paper Mill (BPPM); in regions near urban settlements; and near shore-protection construction operations. The data were compared with material previously collected, and with fish communities sampled in distant (control) areas. Variations in the composition of community are shown: some species that used to be absent were recorded in these areas, and possible reasons for their appearance are discussed. No distinct changes in the littoral fish were found attributable to anthropogenic influences. Recommendations on ichthyologic monitoring are proposed. [ABSTRACT FROM AUTHOR]

Tropical Asia (i.e. the Oriental biogeographic region) is the most densely populated and degraded region on Earth with the highest deforestation rates in the tropics. Flow regulation is a significant threat to riverine biodiversity in the region, and its impacts are combined with overharvesting, pollution and other sources of habitat degradation. In addition to these immediate threats, the potential impacts of exotic species and climate change are difficult to predict. Uncertainty about impact effects arises also from the fact that knowledge of the rich freshwater biodiversity of tropical Asia is incomplete, and up-to-date national or regional inventories are lacking. In part, this reflects taxonomic constraints, and a limited representation of Asian science in the international limnological and conservation literature. A survey of recent (1992–2001) international journals dealing with freshwater ecology and limnology in general, on one hand, and conservation biology on the other, reveal that the representation of scientists based in tropical Asia was extremely low. Scientists from tropical Asia authored fewer than 2% of more than 4500 papers dealing with freshwater biology; 57% of them were published in Hydrobiologia. Less than 0.1% of freshwater biology papers dealt with the conservation of biodiversity in tropical Asian fresh waters. The representation of Asian freshwater science in the conservation biology literature was also poor; 0.6% of 1880 papers surveyed. Such limited dissemination of information reflects a variety of constraints (e.g. manpower, funding, language, and entrenched attitudes), arising from sources both within and outside the region. Even the data that are published are not effectively deployed toward conservation ends. Awareness of some of the more egregious examples of overharvesting (e.g. of river turtles) in the region has increased, but strategies for the protection of riverine biodiversity remain underdeveloped. Where legislation to protect water resources has been put in place, it has been directed towards enhancing human use of water – not biodiversity conservation – and enforcement is weak. Exceptionally, the Chinese government has produced national `Red Data Books' for endangered freshwater vertebrates, and legislation aimed at protecting species at risk, particularly from overharvesting, are in place. Huge obstacles remain, especially in the management of rivers crossing international boundaries. The Mekong River Commission (MRC) provides an example of a model for an international drainage basin that has made significant progress in establishing appropriate structures and mechanisms for sustainable development in a challenging political landscape. Not all of the Mekong riparian states participate in the MRC, and this will be essential for sustainable management. However, even within national borders, local interests can override drainage-basin perspectives. In many places in Asia, preservation of near-pristine freshwater environments is not a realistic option. Sustaining human livelihoods is an over-riding concern, and recognition of this fact must be built in to biodiversity conservation efforts. This has special implications for the management of exotic species, as the example of fish introductions to the Sepik River in Papua New Guinea shows. Notwithstanding the various factors that constrain publication by scientists in tropical Asia, we must recognise that poor dissemination research results will have consequences for the long-term preservation of the habitats and biodiversity that we study. A change in research strategy that establishes priorities, recognises the inevitability of trade-offs, and includes greater emphasis on engagement and partnerships – as in the MRC – is mandated. [ABSTRACT FROM AUTHOR]

A preface for the May 1, 2009 issue of "Hydrobiologia," is presented.

The major results and conclusions of the two papers in the hydromorphology section of the Hydrobiologia special issue on the EU STAR project are summarised. Several key findings have emerged from this research. Firstly, the hydromorphological characteristics of rivers between different geographical regions of Europe were found to vary considerably with rivers in each region possessing distinctive hydromorphological characteristics. Secondly, the hydromorphological attributes that most strongly influence two existing hydromorphological indices (the Habitat Quality Assessment and the Habitat Modification Score) were identified and attention was drawn to the accurate definition and recording of these attributes in field surveys and training courses. Thirdly, links between hydromorphological characteristics and macroinvertebrate quality indices were investigated. Two types of bank modification (resectioning and reinforcement) were significantly correlated with two biotic indices (EPT taxa and MTS), while channel modifications were negatively correlated with ASPT. While biotic indices were often strongly correlated with Habitat Quality Assessment they were less strongly related to Habitat Modification Score suggesting that physical habitat diversity may be more important in determining macroinvertebrate community structure than morphological alteration. The papers in this section provide important underpinning research for the implementation of the European Water Framework Directive. In both papers suggestions are made for further research on the hydromorphology of European rivers. [ABSTRACT FROM AUTHOR]

Introduces articles related to hydrobiology published in the January 2004 issue of "Hydrobiologia."

Crustaceans, a commercially important class of arthropods in fisheries and aquaculture, represent a major worldwide food component for human consumption. Recently, growing interest regarding the ageing and longevity of crustaceans has led to advancement in the field of age determination methods, including the use of lipofuscin and growth band counts, veering from the classic approach of size modal analysis. This manuscript provides a comprehensive overview of literature published between 1990 and 2016 on popular age determination methods (length-frequency analysis, lipofuscin analysis, and growth band counts) applied to five main crustacean taxa (shrimp, krill, crayfish, crabs and lobsters). Of the 231 studies examined, 83% used length-frequency analysis, 13% used lipofuscin and 4% used growth bands. Validation, a necessary step to support results provided by age estimation studies, was included in 71% and 56% of the reviewed published papers that used lipofuscin and growth band counts, respectively. So far, growth band counts have been the only direct method of determining crustacean age. This method requires validation in all species before routine application in stock assessment and/or conservation purposes. [ABSTRACT FROM AUTHOR]

Information about several papers discussed at a symposium on European Marine Biology is presented. Several papers were presented by students and five past presidents of the European Marine Biology Society discussed the papers. The two principal themes of the symposium were Biodiversity and Artificial Habitats.

The main results of the STAR project on the intercalibration of boundaries of European assessment systems and comparison between assessment methods are summarized here. The main findings are outlined in the context of the Water Framework Directive that requires reliable instructions to be set up on how to use and harmonise assessment systems and methods for European rivers. The main papers published on these subjects by STAR partners are reviewed, with focus on major questions addressed and approaches used for investigation. The need for broad coverage of geographic ranges and pressure gradients, together with the goal of providing outcomes appropriate to the effective application of the WFD are emphasized. Extensive datasets from a wide range of countries, stream types and sites and a large number of methods, metrics and approaches are compared and tested and various cross-cutting themes emerged. Among these, the value of the use of benchmarking systems for comparison and intercalibration is highlighted. Two ways of looking for comparability of assessment systems results were analyzed: a) by adopting identical sampling techniques across Europe and b) by harmonizing the classification results of the national assessment systems. In addition, the need, in the intercalibration process, for a proper definition of the criteria for reference conditions is underlined. This is because their imprecision now represents one of the major weaknesses of the whole intercalibration process. Direct and indirect approaches to intercalibration are considered and commented on for their potential use in distinct circumstances. Finally, the use common metrics for the intercalibration process, which make comparability across Europe valid, is tested and indeed encouraged. [ABSTRACT FROM AUTHOR]

Morphological taxonomy is a critical component of all aspects of aquatic biology. Hydrobiologia receives many manuscripts that focus on descriptions of new species of aquatic organisms. We offer suggestions for how these papers can better conform to the stated aims and scope of Hydrobiologia, which read, in part: ‘ Hydrobiologia publishes original articles of interest to a broad and international audience. Purely descriptive work will be considered if it is firmly embedded in a larger biological framework’. In our opinion, taxonomic studies that classify new species are more likely to meet these aims if they state the species concept being used, and include additional experimental, analytical or conceptual analyses. For example, we recommend that studies that use morphological taxonomy also include independent tests of species boundaries, such as multivariate analyses, molecular genetic analyses, and/or tests of reproductive isolation. Given the constraints under which many taxonomists operate, collaboration might be the most effective strategy for achieving these goals. [ABSTRACT FROM AUTHOR]

Freshwater bivalves have been highly threatened by human activities, and recently their global decline has been causing conservational and social concern. In this paper, we review the most important research events in freshwater bivalve biology calling attention to the main scientific achievements. A great bias exists in the research effort, with much more information available for bivalve species belonging to the Unionida in comparison to other groups. The same is true for the origin of these studies, since the publishing pattern does not always correspond to the hotspots of biodiversity but is concentrated in the northern hemisphere mainly in North America, Europe and Russia, with regions such as Africa and Southeast Asia being quite understudied. We also summarize information about past, present and future perspectives concerning the most important research topics that include taxonomy, systematics, anatomy, physiology, ecology and conservation of freshwater bivalves. Finally, we introduce the articles published in this Hydrobiologia special issue related with the International Meeting on Biology and Conservation of Freshwater Bivalves held in 2012 in Bragança, Portugal. [ABSTRACT FROM AUTHOR]

This paper offers a synoptic account of studies on the phytoplankton communities in the deep southern subalpine lakes (DSL) Garda, Iseo, Como, Lugano and Maggiore. The main cause of the degradation of the water quality in the DSL is eutrophication. The euphotic layers of these lakes are trophically different, ranging from the oligo-mesotrophy of lakes Maggiore and Garda to the meso-eutrophy of lakes Iseo and Lugano. The trophic status as estimated by using total phosphorus and chlorophyll a has provided consistent results in agreement with the models proposed by OECD (1982. Eutrophication of Waters. Monitoring, Assessment and Control, OECD, Paris). Though related with chlorophyll a and TP, the Secchi disk depths have significantly underestimated the trophic status of the DSL. Two trophic indices using the algal orders (PTIorders) and species (PTIspecies) were drawn up on the basis of the distribution of phytoplankton along a trophic gradient defined by the application of multivariate methods; the scores emerging from these indices were used to make a definitive ecological classification of water bodies on a scale from 1 to 5, in accordance with the Water Framework Directive. A third index (PTIOE) was computed as the ratio between the annual mean values of the cumulative biovolumes of two groups of algal orders with opposite trophic characteristics. The three PTI indices were highly correlated, providing a consistent classification of the water bodies. The indices proposed in this work were specifically adopted for use in the DSL. However, the criteria for their implementation constitute a robust and impartial tool for assessing similar indices in other lake typologies and for evaluating the degree of specificity of the trophic indicator values assigned to the single phytoplankton orders and species. [ABSTRACT FROM AUTHOR]

A survey of the fauna of hydrobioid gastropods living in ancient Lake Poso in Sulawesi revealed a total of 16 species, 14 of them new, belonging to two genera, Sulawesidrobia and Keindahan gen. nov. Most species occurred on hard substrates, water plants or rootlets of trees. Since only the upper 0.5 m of the lake have been sampled, many more species probably remain to be discovered. Already, Lake Posoȁ9s fauna ranks among the four most diverse hydrobioid lake faunas worldwide. The Sulawesi lakes including Lake Poso and the Malili Lakes are the only lakes where sizeable radiations of hydrobioid and cerithioid gastropods coexist. Outside Lake Poso, hydrobioid gastropods have not been investigated so far apart from a single species reported from Lake Lindoe similar to or identical with S. bonnei [Abbott, 1945. Occasional Papers on Mollusks 1: 1–4], which has its type locality in Lake Poso and may in fact be a complex of species. Therefore endemicity in Lake Poso cannot be estimated nor is it possible to say, whether the radiation is of lacustrine origin. The introduction of alien fish has had a severe impact on the native fish fauna. The impact on the invertebrate fauna is not known but chances are that this survey based on collections from 1991 no longer reflects the original assemblage in the lake. [ABSTRACT FROM AUTHOR]

Amphidromy is a life cycle of fauna found throughout the tropics and subtropics, including representatives from three phyla. Amphidromy involves a life cycle of oceanic larval development, with postlarval migration into streams where growth and reproduction take place. With increasing industrial and urban development in tropical regions, demands for freshwater are continuously growing, resulting in the construction of dams and diversions that break the freshwater continuum necessary for the amphidromous life cycle; thus, jeopardizing many populations of native and endemic tropical stream fauna. Because of this, more quantitative studies are needed to better understand this unique life cycle, which heretofore, has been relatively little studied compared to tropical terrestrial communities. As such, new and quantitative methods are needed to study the immature stages (e.g., postlarvae) associated with amphidromy. In this paper, we introduce two modifications of the original Breder trap that have been designed specifically for standardized, quantitative monitoring of amphidromous postlarval migration. In addition, the two modified traps can be used in a variety of stream settings from natural bed substrates to modified channels with little heterogeneity. The first modification is made of acrylic, with a flat bottom useful in channelized streams or streams with relatively flat, unnatural benthic substrate (e.g., concrete). The second modification is an affordable trap made from polyvinylchloride (PVC) compression couplings, to be used in streams with natural benthic substrates, particularly those with large, embedded and immovable boulders and bedrock outcrops. Both traps were designed for continuous water flow through the traps, providing the necessary rheotactic cue for migrating amphidromous postlarvae, and ameliorating deficiencies of earlier traps not intended for tropical amphidromous fauna. We also make recommendations for standardized use of these traps to facilitate data comparisons among studies. [ABSTRACT FROM AUTHOR]

Amphidromous stream fauna represent three phyla that have a tropical distribution among oceanic islands, with a few continental representatives. This lifecycle involves marine larval development, with postlarval migration, growth and reproduction as adults occurring in freshwater streams. Many tropical archipelagoes are on the brink of heavy commercial development, threatening freshwater resources in tropical regions. Because of this threat and the isolated nature of tropical islands, quantitative studies are needed to better understand this unique lifecycle. In this paper, we present the use of two modifications of the original Breder trap to study the migration dynamics of tropical amphidromous fish and shrimp postlarvae. The first modification was used in a cemented and channelized stream. The second modification was used in two streams with natural substrates of large, embedded and immovable boulders and basalt outcrops. Quantitative trapping was standardized by time and numbers of traps used, to give results presented as postlarvae trap-1 h-1. The number of traps used in the natural streams was based on channel width at the trapping location (i.e., equal number of traps per meter), thus providing equivalent trapping effort between streams of different sizes and flow magnitude. Both trap designs were useful for quantitative monitoring of postlarvae over several months and years, among different streams, and were equally practical for assessing diel and species-specific migration dynamics. Postlarval recruitment of Hawaiian amphidromous species showed temporal variation between months and years within the same stream, significant differences between two streams of different flow magnitude, and distinct diel patterns in diurnal and nocturnal fish and shrimp migration, respectively. A direct correlation between stream flow and total fish postlarval migration was documented. [ABSTRACT FROM AUTHOR]

This paper provides an annotated synopsis of cryptomonad morphology, ultrastructure, taxonomy and nomenclature. Its aim is to aid cryptomonad identification down to whatever taxonomic level is realistically possible, based on currently used taxonomic criteria. It is intended as a `companion', i.e. a tool to be used in conjunction with the existing literature, rather that a self-contained guide making it possible to identify all known cryptomonads. A nominalistic philosophy is adopted as far as possible, whereby taxa are considered to be acceptable as long as their names have been published in accordance with the nomenclatural rules and prevailing taxonomic practice. A new combination is proposed, Pyrenomonas duplex comb. nov. (basyonym: Rhodomonas duplex Hill & Wetherbee). Although identification keys are provided whenever possible, an empirical, multilateral approach is followed with a view to facilitating cryptomonad identification by non-specialists using only what equipment is available to them at any one time. This approach is based on the fact that different degrees of taxonomic resolution can be achieved by using different combinations of observation techniques. Identification rationales are based on the following techniques (in ascending order of complexity, time-consumption, and financial cost): light microscopy, scanning electron microscopy, and transmission electron microscopy, supplemented by freeze-fracture investigations and spectrophotometry. Information given under any one section is cross-referenced to other relevant sections by means of italicized links. It is envisaged that this paper will constitute the core of an interactive identification tool to be published electronically on the Internet in due course. Amongst the factors contributing to the difficulties of cryptomonad identification, the most important appear to be the following: the state of flux of cryptomonad classification systems; typification difficulties, especially the historical disregard for the type method and the incorrect belief that preserved type materials of cryptomonads do not exist; difficulties in relating `classical' taxa and newer ultrastructural descriptions; the description of monospecific genera; inadequate methodology; and the long-standing gap between ecological studies on the one hand and cryptomonad taxonomy and systematics on the other. A wider use of scanning electron microscopy is advocated wherever possible because it appears to be a highly informative and cost-effective tool for discovering, describing, and mapping cryptomonad biodiversity. It is also to be hoped that collaborative projects between ecologists and taxonomic specialists will start to fluorish soon. [ABSTRACT FROM AUTHOR]

Ecological dynamics in many aquatic communities are strongly influenced by spatial and temporal variability of key limiting resources, and the extent to which consumers can locate and exploit concentrations of those resources. This paper presents a non-dimensional index, the Frost number, that provides a simple prediction of availability to consumers of spatially and temporally varying resource concentrations. This index incorporates characteristics of both resource distributions and consumer movement behaviors. The Frost number may provide a preliminary identification of the length and time scales at which resources are available to consumers in complex ecological systems, even when detailed spatial observations and simulations are not available.

This article describes LIMPACS, a research initiative designed by the International Geosphere-Biosphere Program. The LIMPACS programme is designed to assess how and why lakes have changed, are changing and might change in the future as a result of human activity. The article outlines the program's major set of foci, such as: climate forcing, climate variability, land/ocean dynamics, and human-environment interactions. Other papers in this volume are based on a meeting of scientists to develop research priorities.

M-AMBI is a multimetric index for assessing the ecological quality status of marine and transitional waters. It is based on benthic macroinvertebrates and integrates AMBI, a biotic index based on species sensitivity/tolerance, with diversity and richness, making it compliant with the European Water Framework Directive. The success of AMBI paved the way for the introduction of M-AMBI, which was subsequently incorporated into the regulations of several European countries. The M-AMBI algorithm integrates the metrics by means of factor analysis (FA). In this paper, we first reproduced the algorithm using the open source R software. This enabled us to point out that FA is not functional to M-AMBI, and its omission does not appreciably change the results. We then enhanced the applicability of the index, making it independent of the number of samples. In this way, M-AMBI is closely approximated by the simple mean of the normalised metrics with no need for multivariate techniques. Finally, we further simplified the approach, presenting a bivariate version that is still highly correlated with M-AMBI, in which the constitutive metrics are reduced to a diversity measure and a species sensitivity index. The properties of this bivariate version include simplicity, transparency, robustness, and openness. [ABSTRACT FROM AUTHOR]

The Water Framework Directive (WFD) requires estimates of the confidence and precision associated with any scheme for assessing and monitoring the ecological status class of any European rivers, lakes, transitional or coastal waters. This is a complex important issue, especially for waterbody assessments based on multiple metrics and/or two or more taxonomic groups. This paper aims to contribute towards improving understanding and providing practical approaches to assessing confidence of class by (i) discussing the various sources and causes of uncertainty, (ii) using UK rivers macroinvertebrate datasets to illustrate the estimation of replicate, temporal and spatial variance components and the implications for water body metric precision, confidence of class and optimal sampling design, (iii) introducing new freely available general software WISER Bioassessment Uncertainty Guidance Software (WISERBUGS) which uses prior sampling uncertainty estimates with user-specified metrics, class limits and metric combination rules to simulate the joint sampling uncertainty in metric EQR values and provide estimates of confidence of class based on individual metrics, (optionally weighted) multi-metric indices and/or multi-metric classification rules (worst case, mean or median class) based on one or more WFD biological quality elements. [ABSTRACT FROM AUTHOR]

Despite improvements in wastewater treatment systems, the impact of anthropogenic nutrient sources remains a key issue for the management of European lakes. The Water Framework Directive (WFD) provides a mechanism through which progress can be made on this issue. The Directive requires a classification of the ecological status of phytoplankton, which includes an assessment of taxonomic composition. In this paper, we present a composition metric, the plankton trophic index, that was developed in the WISER EU FP7 project and demonstrate how it has been used to compare national phytoplankton classification systems in Northern and Central Europe. The metric was derived from summer phytoplankton data summarised by genus from 1,795 lakes, covering 20 European countries. We show that it is significantly related to total phosphorus concentrations, but that it is also sensitive to alkalinity, lake size and climatic variables. Through the use of country-specific reference values for the index, we demonstrate that it is significantly related to other national phytoplankton assessment systems and illustrate for a single European (intercalibration) lake type how it was used to intercalibrate WFD boundaries from different countries. [ABSTRACT FROM AUTHOR]

The EU-funded research project WISER ('Water bodies in Europe: Integrative Systems to assess Ecological status and Recovery') developed new assessment methods required by the EU Water Framework Directive (WFD) for lakes, coastal and transitional waters. WISER also addressed the recovery of biotic assemblages from degradation. The results are summarised in five key messages, supported by papers in this special issue and by WISER results published elsewhere: (1) Response to stress differs between organism groups, water types and stressors; a conceptual model is proposed summarising how the individual organism groups respond to different types of degradation in rivers, lakes, transitional and coastal waters. (2) The sources of uncertainty differ between BQEs and water types, leading to methodological suggestions on how to design WFD sampling programmes. (3) Results from about 300 current assessment methods indicate geographical variations in metrics but assessments are comparable at an aggregated level ('ecological status'). (4) Scale and time matter; restoration requires action at (sub)-basin levels and recovery may require decades. (5) Long-term trends require consideration; the effects of both degradation and restoration at the water body or river basin scales is increasingly superimposed by multiple stressors acting at large scales, in particular by climate change. [ABSTRACT FROM AUTHOR]

The article introduces various reports published within the issue, including articles based on the proceedings of the Third Symposium on Species in Ancient Lakes and papers responding to demand from some parts of the scientific community.

A preface for the 2010 issue of "Hydrobiologia" is presented.

A preface to the April 2011 issue of "Hydrobiologia" is presented in tribute to hydrobiologist Stanley Dodson.

As MPA networks continue to grow worldwide, decision makers and the public will need to be kept informed regarding progress made in meeting the underlying ecological goals of the networks. The twelve coastal European nations of the OSPAR Commission have agreed to establish within the waters of the Northeast Atlantic an “ecologically coherent” network of marine protected areas by 2010. An initial set of 81 MPAs in the Northeast Atlantic was accepted by the OSPAR Commission in June 2006, and as of 31 December 2006 six additional sites have been put forward. They amount to approximately 26,500 km2, submitted by six of the twelve coastal nations. The job of assessing their ecological coherence has proven to be a difficult issue, and one that has not been attempted before. Assessment techniques that can cope with data-poor situations will prove most helpful, and with this in mind, three general approaches that can be used in data-poor situations and four specific examples of assessment techniques, are presented in this paper. Additionally, a brief summary of the current status of the OSPAR MPA network is provided. [ABSTRACT FROM AUTHOR]

Caprella mutica Schurin is an epifaunal amphipod crustacean which originates in north-east Asia and has spread throughout the world, yet very little is known about fundamental aspects of this species biology. This paper examined the survivorship of C. mutica reared under laboratory conditions at 13–14 °C, 14 h light: 10 h dark photoperiod and fed commercial salmon feed, the diatom Cylindrotheca fusiformis Reumann and Lewin, the macroalgae, Fucus vesiculosus L. and given no additional feed. In addition, growth, maturation and reproduction of C. mutica fed C. fusiformis were assessed. No significant difference in survivorship of C. mutica was observed for the diet types over the experimental period. C. mutica was able to survive for up to 20 days without additional food. Average survival time of males and females fed the diatom, C. fusiformis was 68.8 d (range = 62–73 d) and 82.0 d (range = 76–92 d). Juvenile C. mutica emerged from the brood pouch at a body length of 1.33 mm and moulted at 5.0–11.0 day intervals. Males exhibited faster growth rates than females after Instar VII. Females produced their first brood at Instar VII, 24–26 days post-hatching and with an average body length of 8.5 mm. Each female had an average of two broods sequentially and these were released at 20.2 day intervals. Brood size for a single female increased from 11.3 (±9.9) hatchlings at Instar VII to 25.5 (±11.5) at Instar IX and the maximum number of hatchlings produced by a single female was 82. The results suggest that C. mutica exhibits a number of life-history traits that would potentially enable it to withstand global transportation and to rapidly become established in an introduced region, if environmental conditions are suitable. [ABSTRACT FROM AUTHOR]

Five published indirect methods to estimate benthic secondary production of intertidal mudflats and a new proposed formulation based on quarter-power allometric scaling and the “Universal Temperature Dependence” of biological processes (UTD) were compared. For this purpose, a dataset consisting of an annual series of samples, taken from the Lagoon of Venice from March 1996 to March 1997, at sites characterised by different seagrass coverage was used. All methods resulted in that biomass and secondary production decreased progressively when moving from the seagrass meadow toward areas of unvegetated substrate, suggesting an influence of the available marine phanerogams on the neighbouring sites. The equation proposed in this paper gives results comparable with those obtained using empirical regression models from literature. The main conclusion from this study is that general equations proposed by the “metabolic theory of ecology” can be applied for indirect estimations of secondary production of benthic communities. [ABSTRACT FROM AUTHOR]

A technique for the rapid surveying of submersed aquatic vegetation by post-processing of data collected using a high frequency (420 kHz) digital echo sounder (BioSonics DT4000) has recently been developed and successfully tested in an estuarine environment by Sabol et al. [Sabol, B. M., R. E. Melton, R. Chamberlain, P. Doering & K. Haunert, 2002. Evaluation of a digital echo sounder system for detection of submersed aquatic vegetation. Estuaries 25: 133–141.], where it was used to map the cover and height of freshwater tape grass ( Vallisneria americana) and seagrasses ( Thalassia testudinum, Haladule wrightii and Syringodium filiforme). This technique, which is also spatially referenced by input from a global positioning system, has many potential applications in macrophyte studies in shallow lakes, although it has not yet been extensively tested in such habitats using systems of lower sound frequency. This paper reports such a test in two shallow (maximum depth c. 5.9 m) lakes of the Cotswold Water Park, U.K., using a 200 kHz digital echo sounder (BioSonics DT6000 and DT-X upgrade) and post-processing analysis using the now commercially available software EcoSAV, which incorporates the algorithms of Sabol et al. (). Hydroacoustic assessment of the coverage by macrophytes, mainly Nuttall’s pondweed ( Elodea nuttallii) and charophytes ( Chara spp.), showed high agreement with those recorded during a simultaneous visual survey by underwater video recording ( r 2 = 0.8478, n = 74, P < 0.001). Assessment of macrophyte height was also apparently consistent between the two systems, although the video system could not produce quantitative data and so statistical assessment of the agreement was not possible. Repeated hydroacoustic surveys over the course of the winter of 2003–2004 were conducted in one lake and illustrate the application of this new macrophyte survey technique. Such applications include the rapid measurement of mean Percentage Volume Inhabited (PVI), which fell from 12.15% (95% confidence limits, ±0.55%) to 7.10% (±0.40%) over the course of the winter. [ABSTRACT FROM AUTHOR]

Two experiments were conducted to investigate the effects of competition on growth and performance of Nymphoides peltata (Gmel.) O. Kuntze in microcosm. Part of the research on growth and biomass allocation of N. peltata in response to competition had been reported early (Wu, Z. & D. Yu, 2004, Hydrobiologia 527: 241–250). This paper focuses on the morphological variations of N. peltata under competitive pressure. First, competition between N. peltata and Zizania latifolia (Griseb.) Turcz. ex Stapf. was assigned with the densities of N. peltata to Z. latifolia ratios of 4:0, 4:2, 4:4 and 4:8. Water surface coverage, surface area per leaf blade and number of leaves per plant of N. peltata all declined significantly with increasing density of competitor. Similar results were also found for petiole length and density of branching. However, the variations of planting density did not significantly affect the number of ramets per plant and the stolon length of N. peltata. Second, competitions between N. peltata and emerged Z. latifolia, floating-leaved Trapa bispinosa Roxb. and submerged Myriophyllum spicatum L. were also studied simultaneously. The results showed that significant difference was only found for the water surface coverage of N. peltata. No other significant differences were found for the number of ramets per plant, number of leaves per plant, density of branching, surface area per leaf blade, petiole length, and stolon length of N. peltata. Our studies indicate that N. peltata presents morphological variations when it is growing with Z. latifolia, such that the growth of above-ground parts decrease (i.e., leaf number, petiole length, branching density) and the growth of below-ground parts remains stable (i.e., stolons length). However, N. peltata does not show apparent differences in morphology when it is growing with T. bispinosa or M. spicatum. Accordingly, we conclude that the growth of N. peltata may be apparently inhibited by the presence of Z. latifolia, while T. bispinosa and M. spicatum may have little impact on the growth and performance of N. peltata. [ABSTRACT FROM AUTHOR]

In a first biomarker-based study in Lake Baikal, we demonstrated that the heat shock protein Hsp70, a biomarker of exposure, is present in various endemic sponge species of the lake. The expression of Hsp70 was induced following heat stress in tissue or dissociated cells of the Baikalian sponges, Baikalospongia intermedia, Lubomirskia fusifera, and Lubomirskia abietina. Increased Hsp70 levels were still visible after a recovery period of 24 h. Exposure of B. intermedia to lead (Pb) and zinc (Zn) caused a strong induction of Hsp70 in this sponge, while copper (Cu) was not effective. However, all these heavy metals were able to induce DNA damage, a biomarker of effect, in B. intermedia, as determined by Fast Micromethod. Induction of DNA damage in B. intermedia was also observed after exposure to the organochlorines tetrachloroguaiacol and pentachlorophenol, which are released by pulp bleaching. The Baikalsk Pulp and Paper Plant (BPPP) is considered to be one main potential source of pollution of the lake. Investigations of the influence of the waste water from the final refinement and aeration pond of BPPP revealed a concentration-dependent increase in Hsp70 expression in B. intermedia. In addition, the effluents of the pond were able to induce DNA damage. The basal level of DNA single-strand breaks/alkali-labile sites in B. intermedia collected close to the site where the BPPP effluents are discharged into the lake was higher than that in sponges collected at an unpolluted site. Our results suggest that Baikalian sponges are suitable bioindicators to monitor water quality and ecosystem health of the lake. [ABSTRACT FROM AUTHOR]

Two endemic Baikal species of oilfish, Comephorus dybowskii (“small golomyanka”) and Comephorou baicalensis (“big golomyanka”) live in the pelagic zone down to the bottom (1600 m). Both have numerous adaptations to the pelagic habitat. In this regard, the paper gives results of studies of blood under various natural conditions. The cell composition of peripheral blood does not differ between the species. Light and electron microscopy showed absence of granulation in polymorphic nuclear leukocytes. Significant differences in shape (number eccentricity) and sizes of mature erythrocytes were apparent. Parameters of red blood and cytometric indices do not change significantly within each species. However, high values of variation coefficient in the parameters of white blood were observed in both. Small golomyanka in comparison with big golomyanka have a higher percentage of erythroblasts, haemoglobin concentration and oxygen capacity of blood (OCB), while the percentage of polymorphic nuclear leukocytes and mature erythrocytes is less. Both species differ only insignificantly in number of erythrocytes, leukocytes, haemoglobin concentration in erythrocytes, index of leukocyte abundance, and thrombocytes per unit of blood volume. Small golomyanka caught at different depths do not differ much in most parameters of blood, but our analysis shows a high positive correlation between habitat depth, haemoglobin concentration and erythrocyte number per unit of blood volume. Blood characteristics indicate that small golomyanka is the more metabolically active species. [ABSTRACT FROM AUTHOR]

The paper presents an analysis and discussion on a phenomenon of Lake Baikal spring phytoplankton known as ‘melosira years,’ or high-productive years, which are years when spring a psychric set of planktonic algae intensively blooms in the interstitial water within the thawing ice and in the under-ice water. Alternative of these high- and low-productive years is one of greatest baikalian mysteries long attracting researchers’ attention. Analysis of a sequence of high-productive years from 1943 to present, allowed us to reveal 11- and 10-year cycles in long-term dynamics of the Lake Baikal spring phytoplankton. Within these basic cycles we have found enclosed three intervals between high-productive years. Moreover, these intervals being usually 3 and 4 years long became doubled, i.e., 6 and 8 years long, from 1968 to 1990 that equals 22 years in length, or two 11-year fragments. This phenomenon of doubling can be explained in terms of the resonance theory so we consider the ‘melosira years’ phenomenon to be bound up with solar activity, resonantly influencing baikalian phytoplankton. Also we found that Lake Baikal spring phytoplankton skip between their 11- and 10-year cycles in conforming to a current solar activity length. [ABSTRACT FROM AUTHOR]

The European list of aquatic macro-invertebrate taxa, and its associated ecological database, originated within the context of the AQEM project and have been extended during the STAR project. The AQEM/STAR taxalist is a product of co-operation between applied freshwater ecologists and scientists from different zoological fields, applied partners and the administration. The basic idea is that a sound understanding of benthic invertebrate ecology is a prerequisite for the implementation of a biological approach to aquatic ecosystem management in Europe. The database has been generated under the management of BOKU (University of Natural Resources and Applied Life Sciences, Vienna) and UDE (University of Duisburg-Essen) and provides an important means of standardisation and unification of ecological classifications in Europe. This paper outlines the aims for setting up the AQEM/STAR macro-invertebrate taxalist and autecological database and provides a current summary of the numbers of aquatic orders, families, species, and species occurrences in 14 European countries. The number of available and applicable assignments of taxa to each ecological parameter is summarised and examples are given for different parameters and taxonomic groups. Gaps in the autecological information are identified and discussed. Besides its ecological relevance, the operational character of this database is underlined by the fact that it provides the associated taxon codes for each of five different European assessment systems for nearly 10,000 European macro-invertebrate taxa. [ABSTRACT FROM AUTHOR]

The study of the population dynamics of aquatic oligochaetes is still largely a descriptive subject. However, going beyond description is essential in any field of science. This paper analyses the methodological approaches that can be used in this process, together with some examples from each of these approaches as they have been applied to aquatic oligochaetes. Observation and experiments in the field, laboratory experiments, and mathematical models are reviewed. Increased use of tools that are regarded as standard in the field of population dynamics at large and interaction with applied disciplines are advocated as ways to improve the quality of research in this field. [ABSTRACT FROM AUTHOR]

Biological aerobic wastewater treatment plants (WWTPs) produce a lot of excess sludge. The costs for handling this residual product are increasing, so the search for alternative techniques to reduce the amount of sludge has to be continued. Activated sludge consists of inorganic and organic substances, bacteria, protozoa and metazoa. Due to incomplete biomass conversion, sludge consumption yields less oligochaete biomass. From a technological point of view, the application of aquatic oligochaetes to reduce the sludge production offers interesting perspectives. This paper aims to review the feasibility for the reduction of activated sludge in WWTPs by means of aquatic oligochaetes. Also the current techniques concerning sludge reduction are taken into account. Several of the WWTPs relevant parameters, which may influence predatory activity of aquatic oligochaetes, are discussed: particle size, organic content of substrate, bacteria preference, life cycle and population dynamics of aquatic oligochaetes, temperature, pH, oxygen and process conditions. From the literature it appeared that most research has been performed on laboratory scale. Only a few authors mention a significant reduction of the sludge production by ‘sessile’ species such as Lumbriculus. Vermicultures for the reduction of activated sludge are rather common in developing countries. Incidentally large annelid blooms have been noticed in WWTPs. It remains obscure which factors trigger the initiation of annelid blooms in WWTPs and which are of importance to maintain a stable annelid population in WWTPs. The influence of a considerable worm bloom on the waste sludge production is still under investigation. [ABSTRACT FROM AUTHOR]

For avoiding the unfavorable environmental conditions several aquatic microorganisms are capable of forming specialized resistance cells like akinets, hypnospores, statospores, etc. Recognition of the important role of cysts in the life cycles of dinoflagellates increased the need to study their role in the ecology of phytoplanktons, and this, combined with the knowledge of chemical and biological characteristics of the water, may lead to a better understanding of the spatial and temporal dynamics of dinoflagellates. This paper reports on the effects of temperature, nitrogen, and phosphorus on the percentage of encystment of the dinoflagellate Peridinum cinctum Stein. The phosphorus content of the medium affected encystment only at the highest temperature applied (22 °C). Nitrogen content and temperature were the most important factors controlling the encystment. [ABSTRACT FROM AUTHOR]

This paper describes results of partial destratification of a large reservoir with complex morphology. In order to reduce phytoplankton growth by light limitation, the upper 20 m of the water column were destratified in the Bleiloch Reservoir (Thuringia, Germany). Temperatures, phytoplankton, and zooplankton were investigated before and during aeration to determine the effects of the partial destratification on plankton. The measure induced an increase of phytoplankton dynamics. Since 1991 nuisance cyanobacteria blooms increased in the hypertrophic Bleiloch reservoir (Thuringia, Federal Republic of Germany), as light conditions improved due to a reduction of coloured wastewaters supplied by a cellulose mill. Warm inflowing water formed an upper layer, which reached the bubble plume near the dam, and was only weakly affected by the deeper mixed water body. The water column stability decreased, which caused an overturn 2–3 weeks earlier, because the hypolimnion warmed up faster. These physical effects of the destratification delayed the seasonal succession of phytoplankton. Cyanobacteria were suppressed but diatoms and chlorophytes became more abundant. Copepods maintained higher population densities throughout the summer. During artificial mixing, the algal diversity increased, not only because k-strategists selected a stratified water column, but also because episodic thermal instability enabled r- and k-strategists to co-exist in a competitive environment. [ABSTRACT FROM AUTHOR]

In Asia, especially in China, our knowledge of the distribution of testate amoebae is still limited. In this paper, the geographical distribution of testate amoebae in Tibetan Plateau and northwestern Yunnan Plateau, southwest China and their relationships with the climatic factors have been studied. We found testate amoebae shifted in the most dominant species and increased in species (or genus) richness from northwest to southeast. Further, the linear regression analyses revealed that both species richness and genus richness have higher positive correlations with the mean temperature of the warmest month and annual mean precipitation as contrasted with the mean altitude, which showed weak negative correlation. This indicates that the temperature and precipitation are more significant influences on the richness than the altitude. The cluster analysis based on the community structure, defined by Sørenson’s coefficient matrix, suggested four groups from the 10 physiographical regions. This geographical distribution pattern was also closely related with the climatic regionalization. The present climatic regionalization pattern of the study area originated from the uplift of Tibetan Plateau and mainly occurred in or after the late Pleistocene. Therefore, the geographical distribution of testate amoebae in our study area may have experienced complicated and drastic changes corresponding to the variation of the climate caused by the geological events. [ABSTRACT FROM AUTHOR]

Aquatic macroinvertebrates living in anastomosing lowland rivers use different habitats and respond differently to the hydrological regime. In this paper, the structure and composition of benthic, drifting and marginal macroinvertebrate assemblages are analyzed in the lowland river Ctalamochita (Córdoba, Argentina). The assemblages were studied in an annual cycle; a comparison among the composition of benthos, drift and marginal fauna was carried out; and size structure of the assemblages was characterized. Samples were obtained from two sites: a rural and an urban site. In total 73 taxa of aquatic macroinvertebrates were collected. Benthos was characterized by Chironomidae and Oligochaeta; marginal fauna was mainly constituted by Coleoptera, Heteroptera, Decapoda, the Trichoptera Nectopsyche sp., Ephemeroptera and Odonata. Drifting assemblage was composed by macroinvertebrates from local and remote upstream benthos, and from the marginal zone. Marginal fauna diversity was higher than benthos and drift. Total biomass of the assemblages pooled together was relatively equitably among size classes. Larger size classes consisted of organisms from the marginal zone whereas the smallest ones were composed by benthic and drifting organisms. In the study area there is habitat partitioning in the lateral dimension of the river. Marginal fauna was more diverse due to the asymmetry of transport and deposit processes, which generate a heterogeneous habitat in the bankside. The relation between fine substrate and high current velocity determines an unstable habitat in the central channel, which makes colonization by benthic macroinvertebrates difficult. [ABSTRACT FROM AUTHOR]

This paper reports the results of a study on a zoosporic fungus (Saprolegniaceae) parasitizing populations of Eudiaptomus intermedius (Copepoda, Calanoida) in mountain lakes located in the Northern Apennines, Italy. The dynamics of this infectious process was previously described in one of the lakes of the study area. The virulence is particularly high at the end of the calanoid reproductive phase, when the fungal hyphae penetrate the host eggs provoking their degeneration. Here new data are presented and the phenology of the host–parasite interaction is comparatively analyzed in different years and in different sites. The occurrence of the parasite was assessed at a regional scale. Possible mechanisms involved in the pathogen dispersal and in the host recognition are proposed, and the ecological impact of the fungal parasitism on the calanoid populations is discussed. [ABSTRACT FROM AUTHOR]

This work introduces an interpretational key to quantify and understand how much of variations among lakes in fundamental ecosystem characteristics that may be related to lake morphometry, catchment area features, measurement uncertainties and other factors (mostly climate). The size and form of lakes regulate many general transport processes, such as sedimentation, internal loading and outflow, which in turn regulate many abiotic state variables, such as concentrations of phosphorus, colour, water chemical variables and water clarity, which regulate primary production, which regulate secondary production. This paper discusses relationships between key abiotic state variables, lake morphometry and catchment area characteristics using empirical/statistical analyses based on data from 95 lakes. It has been shown that of the studied variables Secchi depth depends most on morphometry (34%); 31% of the variations among the lakes in Secchi depth may be related to catchment area characteristics, 1% to uncertainties in empirical data and 34% to “other” (climatological) factors. The corresponding figures for alkalinity, which depends least on lake morphometry are, 0% related to morphometry, 34% to catchment conditions, 1% to empirical uncertainty and 58% to other causes. For all other studied variables, i.e., conductivity, hardness (CaMg), calcium, iron, colour, pH and phosphorus the corresponding figures vary between these values. The interpretational key helps to explain the mechanistic reasons for these statistical/empirical results. [ABSTRACT FROM AUTHOR]

Lake Illawarra, is a typical shallow intertidal coastal barrier lagoon in New South Wales, Australia. This paper reports the first examination of photosynthetic characteristics of benthic microalgae and seagrass in this lake by measuring the oxygen exchange procedure (flux) using sediment-core incubations in the laboratory. Photosynthesis vs irradiance relationships (P–I curves) were generated from measurements made at nine irradiances for microphytobenthos (MPB) at five different water depths (sites) during September 2002. Maximum benthic gross primary production (GPmax) for MPB in this lake tended to decrease with the increasing water depth from Site 5 (about 0.2 m deep) to Site 1 (about 3.0 m deep), and was correlated with decreasing surface sediment Chl-a concentrations. [ABSTRACT FROM AUTHOR]

Understanding of migration patterns is essential in the interpretation of hydro-acoustic stock assessment data of partly demersal partly pelagic fish stocks. In this paper we provide this kind of information for some species that were common in the Mwanza Gulf of Lake Victoria in the 1980s, before and after the upsurge of introduced Nile perch (Lates niloticus). Detritivorous haplochromines and Nile tilapia (Oreochromis niloticus), both stay near the bottom during day and night. Feeding seems to occur predominantly during the day. The zooplanktivorous haplochromines and dagaa (Rastrineobola argentea) dwell near the bottom by day and migrate towards the surface during the night. They seem to follow their prey, zooplankton and lake-fly larvae. Piscivorous nembe (Schilbe intermedius) show similar migration patterns to zooplanktivorous fishes, but their behaviour cannot be unambiguously explained by pursuit of prey. Nile perch to some extend migrate into the column at night, though the majority remains near the bottom. Feeding takes place during day and night. [ABSTRACT FROM AUTHOR]

The present paper focuses on the biological properties of Lake Chapo prior to the installation of a hydroelectric power station. Most of the biological parameters indicate that the lake is oligotrophic, i.e., it has very low values of chlorophyll a and primary production. The phytoplankton community of 73 species shows a predominance of only a few species in terms of density and biomass. The zooplankton community is poor in species, with one of the lowest densities measured in the North Patagonian lakes. The fish community is dominated by two introduced salmonid species. Comparison with other North Patagonian lakes reveals that Lake Chapo is the most oligotrophic. [ABSTRACT FROM AUTHOR]