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Architeuthis dux diet has been analysed according to information available from literature and from the analysis of gut contents of five females and two males from Mediterranean and Atlantic Iberian waters (20 specimens in total). This is the first time that A. dux diet from Atlantic and Mediterranean waters is described. Body weight of specimens ranged from 22.5 to 200 kg. In order to infer common patterns in giant squid diet according to its geographic distribution range, size and sex, available data on their diet composition structure were joined and examined with multivariate techniques. No significant differences in the trophic level on which A. dux prey on were found, considering size, sex and location. Thus, A. dux seems to play the same role in the trophic webs throughout the distribution range examined in this paper, which takes up a very wide geographic area. The trophic level estimated from the diet composition is 4.7. Obtained results show that this species preys mainly on pelagic fast swimmers and shoaling fishes and cephalopods as an opportunistic ambushing hunter. [ABSTRACT FROM AUTHOR]

Presents several books related to hydrobiologia.

This editorial is aimed at explaining why the editors of Hydrobiologia are so concerned with biological nomenclature and why we ask our authors the utmost precision when referring to species in their papers. In fact, the name of the describer that follows the binomen (genus name + species epithet) not only offers information about who described that species (and eventually when) but in some way summarises the "history" of the classification work that was necessary to describe that species. E.g., I Anguilla anguilla i (Linnaeus, 1758): Linnaeus described this species as I Muraena anguilla i and later on the species was moved to the genus I Anguilla i . [Extracted from the article]

Online searches for relevant scientific references using keywords have become common practice. Several multidisciplinary scientific online databases are available, of which Web of Science, Scopus (both payable) and Google Scholar (free of charge) are the most commonly used. We test the hypothesis that results of highly similar searches in these three databases do not necessarily give comparable results. We set out to query the three databases with a real example on "diapause in microcrustaceans" (Cladocera, Copepoda and Ostracoda), using the same time period (2012–2021), the same keywords with the same syntaxis and the same sorting criterion ("relevance"), and compared the first 100 hits provided by each database. There were several references provided which were irrelevant to the search, especially in the Web of Science, and of the remaining relevant references, only 9.84% were provided by all three databases. Our survey showed significant differences amongst the results provided by the databases, especially for "hydroperiod" and "type of environment". These differences can be the result of different coverage of the scientific literature by the databases, but also of the different ways by which the criterion "relevance" is calculated by the three algorithms. We, therefore, recommend that literature surveys must be based on several databases; otherwise, the results might become biased. [ABSTRACT FROM AUTHOR]

The analysis of ecological niche is an important task to correctly identify the role exerted by species within ecosystems, to assess their vulnerability, to plan effective measures addressed at fulfilling the postulates of biological conservation, and ultimately to prevent biodiversity loss. However, for the majority of organisms our knowledge about the actual extent of their ecological niche is quite limited. This is especially true for microscopic organisms. Evidence exists that in different geographical areas allegedly conspecific populations can show different, if not antithetical, ecological requirements and not-overlapping ecological niches. This opinion paper discusses whether this "niche displacement" effectively occurs between conspecific populations or if the pattern is rather due to an inaccurate identification of species and/or to an insufficient knowledge about population and community ecology. Hence, some subjectively selected study cases when alleged phenomena of niche displacements take place are presented, and shortfalls in the correct assessment of the identity and ecological niches of microscopic aquatic eukaryotes, namely phytoplankton, zooplankton, and meiofauna are shown. [ABSTRACT FROM AUTHOR]

The impacts of biological invasions remain poorly known for some habitats, regions and taxa. To date, there has been no comprehensive effort to review and synthesize the impacts of invasive mollusc species in South America. In this paper, we provide a synoptic view on what is known on documented socio-ecological impacts of aquatic no-native mollusc species (NNMS) and transplanted mollusc species (TMS) from South America. An expert group involving malacologists and taxonomists from different countries, the "South America Alien Molluscs Specialists" (eMIAS), shared and summarized the scientific literature, databases, and published and unpublished information on confirmed impacts of NNMS and TMS in South America. Three broad categories, non-mutually exclusive were used as a framework: "Environmental/Biodiversity impacts", "Economic and social effects", and "Human health impacts". Some 21 NNMS and seven TMS have documented impacts on at least one of those three categories. We encourage targeting the less known areas of research, such as economic valuation of human health (and veterinary) impacts attributable to NNMS or TMS and expand our knowledge of environmental impacts for the species listed in this study. [ABSTRACT FROM AUTHOR]

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

The global and seemingly unstoppable spread of invasive alien plants emerges as one of the main topics of current science. This is due to the multiple repercussions of invasive plants on biodiversity and ecosystem functioning, plus huge consequences on human existence. In freshwaters, lots of invaders are extremely competitive by virtue of their idiosyncratic reproductive and adaptive strategies. As "inland islands", freshwaters seem particularly prone to changes when invaded, such as reorganisation of food webs and biotic interactions. Together, these events are self-reinforcing, implying hardly reversible hysteric phenomena. The intention of this paper is to point out: invasion pathways, driving factors, invasion mechanisms, and noticeable effects mediated by plant invaders in freshwaters through an extensive knowledge review. The growing evidence suggests the dawn of a new epochal phase: a globally alien-dominated "bio-historical horizon", tentatively called "Exocene", where invaders play predominant roles that drive freshwaters functioning and successional unexpected stages. In the context of invasion science, Exocene reinforces the need for an ecosystem-based perspective to properly understand the implications of plant invaders in freshwaters. Seven challenging issues emerge to be addressed to better outline the global paths of biodiversity and functioning between biomes when faced with biological invasion. [ABSTRACT FROM AUTHOR]

phylogenetically diverse set of seventeen isolates of Chytridiomycota were selected for a study of the utilization of common carbohydrates as sole carbon sources in synthetic media. Rhizophlyctis rosea AUS 13 is capable of the digestion of crystalline cellulose in the form of lens paper, filter paper and powdered filter paper and grows well with noncrystaline carboxymethyl cellulose or cellobiose, but cannot use starch or maltose as sole carbon sources in liquid and on solid media. None of the other sixteen isolates tested can digest crystalline cellulose, but all grow well on starch and maltose and several can also use cellobiose and/or sucrose as a sole carbon source. Four of the other sixteen isolates could also digest carboxymethyl cellulose slowly. Glucose is an excellent sole source of carbon in synthetic media for all seventeen isolates in the present study. In general, these data suggest variability in the ability of zoosporic true fungi to use carbohydrates other than glucose as sole sources of carbon. Four patterns of carbohydrate utilization emerged from this study of seventeen isolates. R. rosea degrades cellulose over a relatively wide pH range which suggests that the cellulase enzymes are stable over a wide pH range. [ABSTRACT FROM AUTHOR]

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]

This article presents information about the International Conference on Coelenterate Biology. All but one of the contributions on neurobiology were part of a symposium on that subject. Three of the five presentations made in the session on Pioneers in Coelenterate Biology are published here. The symposium has its own introduction, which summarizes the contents of the 15 papers presented in it, and highlights the variability in coelenterates that makes them so interesting and challenging to study. Papers deal with pattern formation both within individuals and in the colonies that many of our marvelously varied animals form.

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]

Oyster larvae initially have an eyespot on settlement stage (pediveligers). This study investigated the eyespot with light wavelength-dependent absorbance, and its functional details for settlement in the Pacific oyster Magallana gigas larvae. Eyespot efficiently absorbed 500–650 nm of light wavelength. Based on the eyespot absorbance, pediveligers were subjected to different light conditions with light-emitting diodes (LEDs): near ultraviolet (NUV), blue, white, green, red, and near infrared (NIR), set at 3 intensities (5, 15, 25 W/m2, except for NIR, which was at 25, 50, 100 lux). LEDs modulated at each intensity were continuously irradiated for 2 days, and the number of settled larvae on a substrate of shell chips was counted daily. NUV at 15, 25 W/m2, and white and green light at 5, 15 W/m2 disrupted larval settlement, whereas red at 25 W/m2 and NIR at 100 lux showed strong settlement-inducing activities. Red and NIR were further tested with ceramic paper substrates; inert substrates. These lights maintained their performance, with settlement rates higher than controls in darkness. Our findings contribute to the further understanding of the function of eyespot in the settlement of oyster larvae, and to establish criteria to evaluate light pollution levels for protecting benthic ecosystem. [ABSTRACT FROM AUTHOR]

We gathered taxonomic information regarding the occurrence of rotifers in Antarctica and Subantarctica, producing a database of more than 1100 records from all 93 papers published on the region since the start of research expeditions in the far South. From this literature review, we outline a history of rotifer research in Antarctica. Then, using the database, we address specific questions on biogeographic patterns in species richness in rotifers in Antarctica and Subantarctica. We highlight a complex scenario of differences between areas and latitudinal gradients, differentially affected by problems in sampling bias. The number of species of monogonont rotifers seems to decrease with increasing absolute latitudes, whereas the number of species of bdelloid rotifers generally increases with increasing absolute latitudes. [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]

The amazing morphological diversity of phytoplankton has to be considered an evolutionarily driven compendium of strategies to cope with the strong variability and unpredictability of the pelagic environment. Phytoplankton collects unicellular and colonial photosynthetic organisms adapted to live in apparent suspension in turbulent water masses. Turbulence represents a key driver of phytoplankton dynamics in all aquatic ecosystems and phytoplankton morphological variability is the evolutionary response of this group of photosynthetic organisms to the temporal and spatial scales of variability of turbulence. This paper reviews the existing literature on the effects exerted by turbulence on phytoplankton populations and is aimed at showing how deeply turbulence contributes to the shape and size structure of phytoplankton assemblages. Our aim is to explore how turbulence governs phytoplankton access to resources and, at the same time, how the shape and size structure of phytoplankton represent the evolutionary way in which this group of organisms has optimised its survival in the highly dynamic aquatic environment. The paper is intended to serve as an homage to the (phytoplankton) ecologist Colin S. Reynolds. His life-long work highlighted how profoundly the ecology of phytoplankton depends on the physical constraints governing the movements of the water masses in which phytoplankton evolved and lives. [ABSTRACT FROM AUTHOR]

An introduction to articles in the issue is presented on topics including ostracods distribution in aquatic environments, the effect of changes in sediment inputs, and importance of phosphorus and light for phytoplankton communities.

We carried out a literature review to investigate the taxonomic and functional β diversity of zooplankton and its species replacement (βrepl) and richness difference (βrich) components in Brazilian rivers. In addition, the taxonomic (LCBD-t) and functional ecological uniqueness (LCBD-f) were also measured. We tested the following hypotheses: (i) The βrepl component is the main driver of taxonomic β diversity, while βrich is most important for functional β diversity, due to functional simplification; (ii) Sites with lower taxonomic and functional richness are the ones that most contribute to LCBD. Contrary to expectations, βrich drove the taxonomic and functional β diversity. This may have occurred due to environmental constraints and geographic distance, thus causing a loss or gain of species and traits between hydrographic regions. For just two regions, the sites with the lowest functional richness were the ones that most contributed to LCBD-f. This reinforces that sites with lower richness can support species that perform unique functions in the ecosystem. As studies involving zooplankton from lotic systems are still limited in Brazil, we suggest that future research should consider the patterns of β diversity in these dynamic, diverse, and threatened aquatic ecosystems. [ABSTRACT FROM AUTHOR]

The application of modern molecular methods and phylogenetic approaches saw an explosion in cyanobacterial taxonomy in the first two decades of the twenty-first century. The relative ease of description of new taxa and the pressure to publish a high number of scientific papers has created apparent confusion. The situation is particularly complicated for ecologically oriented limnological research and practical hydrobiologists especially have numerous criticisms of this trend. On closer observation, however, the situation is not as tragic as it first appears. More than a thousand new species have been discovered or renamed and only 18 percent are freshwater planktonic species, which garner the most interest in routine analyses. Most new taxa are described from terrestrial habitats. Despite the increase in studies from tropical areas, most of the new species are from the temperate zone, which probably does not account for the reality. Significant advances in modern taxonomy are visible mainly for the trichal types, but other groups such as the pleurocapsal species are considerably less studied. In this article I try to show that, despite all the difficulties and limitations, it is not necessary to consider these rapid changes as a complication in common cyanobacteriological research. [ABSTRACT FROM AUTHOR]

Urban ecology is a promising research field in limnology, but we still need to evaluate how urban waterbodies can sustain biodiversity. In this paper, we present a comprehensive foodweb perspective of urban waterbodies in the city of Montréal (Québec, Canada). The research goals are to evaluate if biodiversity and community structure of foodweb components (phytoplankton, zooplankton, and macroinvertebrates) are valuable tools for assessing the ecological status of urban waterbodies and examine how they are controlled by multiple factors related to trophic status and habitat complexity (origin, water residence, macrophyte cover, fish, and management practices). Multiple factor analysis, correlations, and non-parametric tests were used to examine the relationships between the environmental factors and foodweb biological variables. Our case study confirms that urban waterbodies are important sources of biodiversity and reveals that foodweb-based biological indicators are reliable tools for the biomonitoring of urban waterbodies. Foodweb biodiversity and community structure were more influenced by habitat complexity than by trophic status. The key determinants of variation were the differences in water regime, management of temporary and permanent waterbodies, and contrasts in habitat complexity depending on pond origin (artificial or natural) and macrophyte cover. [ABSTRACT FROM AUTHOR]

In this Themed Section, two papers addressed plant invasions in wetland ecosystems and non-hydrophyte species that exist in re-flooding conditions. The above-ground biomass, the heights and areas of tussocks, the names and number of species on each tussock were measured, the proportions of non-hydrophyte species (PNH) were calculated. Guest editors: Haitao Wu, Junhong Bai, Yongjiu Cai & Feng Li / Freshwater Wetlands: Biodiversity, Functioning, Restoration and Utilization The fundamental importance of freshwater wetland resources, the conservation of freshwater biodiversity, and the restoration and utilization of freshwater wetland ecosystems together signal a preeminent need for renewed scientific focus and greater resources. [Extracted from the article]

We present a summary of responses to our call among scientists working on Anostraca to commemorate the late Professor Graziella Mura, a pioneer of modern studies on this group of animals. Colleagues from all over the world promptly answered and contributed their works among which we selected the fourteen papers published in the Hydrobiologia Special Volume 'New Challenges in anostracan research: a tribute to Graziella Mura'. Although Anostraca are widespread globally, they are among the least known taxonomic groups. Although some biogeographical data are available for some species and higher taxa, we are still far from a clear understanding of the phylogeny, ecology and biogeography of the order. The papers collected in this Special Volume are therefore intended to represent a step ahead to solve phylogenetic and ecological issues relative to this charming group of crustaceans. [ABSTRACT FROM AUTHOR]

Littorella uniflora (Plantaginaceae) is a scarce and declining aquatic plant in Europe. Its population has been strongly reduced by changes in fishpond management (eutrophication) in the Czech Republic since the 1950s. We studied its seed bank in both recent ( n = 8) and historical localities (the last found from 1972 to 2000; n = 10) and tested the effects of sediment type and burial depth on seed germination using extracted seeds from two recent populations. The seeds were found in 60% of the historical localities, mostly in low densities (≤6 seeds per 3.75 l of sediment), and also in 100% of the recent localities in various densities (8-1390 seeds per 3.75 l of sediment); however, low germination rates (0-13.3%) were estimated. The seeds germinated best on wet filter paper, followed by nutrient-rich fishpond sediment, but poorly on sand mixed with different substrates. Burial depth significantly affected seed germination. The seeds germinated only on the soil surface and at the depth of 1 cm but no seed germinated at the depth of 3 and 5 cm. Besides low water transparency, both high rate of sediment accumulation and the absence of summer drainage may endanger L. uniflora populations in fishponds. [ABSTRACT FROM AUTHOR]

Cobias (Rachycentron canadum) are large fish that live in all the tropical oceans of the world, except for the Eastern Pacific Ocean (EPO). During 2015, a cobia cage culture was initiated in the EPO off Ecuador. Thousands of cobia individuals escaped from the culture, and the location of the escapees is unknown. In this paper, we used a Maximum Entropy (MaxEnt) model to assess the preferential habitat of cobia in a portion of its natural occurrence range and used the model to predict the potential invasion zones of cobia in the EPO. The model performance was satisfactory (75–93% accuracy). Mixed Layer Depth (MLD) was the most important environmental variable. Cobia inhabits waters near the continental shelf, with a shallow MLD. Five important zones of high probability of invasion were detected in the EPO: one in the southern California Current, one in the Central Mexican Pacific, one off Guatemala/El Salvador, one in a latitudinal band that detaches from the coastline of Central America, and one off Northern Chile. There is an important seasonal variation of the zones of high probability of cobia invasion, variation that is apparently related to the seasonal cycle of different large-scale and mesoscale systems. [ABSTRACT FROM AUTHOR]

The authors examine the relationship between the extent of inaccurate citation in published ecological literature and journal impact factor (IF). They cite the factors that contribute to the problem of poor citation practices including financial incentives for publishing houses. They describe the citations examined and judged. They also present the average accuracy calculated for a range of journals by IF.

The current trend of continuous biodiversity loss resulted in several international and national regulations and funding schemes to target biodiversity protection and halt its loss. Conceiçao et al. ([3]) use niche-based models to predict changes in ostracod diversity in South America as a result of future climate change in order to formulate evidence-based management plans for aquatic ecosystems. Guest editors: Koen Martens, Sidinei M. Thomaz, Diego Fontaneto & Luigi Naselli-Flores / Emerging Trends in Aquatic Ecology IV Our understanding of aquatic ecology and ecosystem functioning continuously improves. [Extracted from the article]

The first studies of diatoms and river pollution were carried out 60 years ago, and the suitability of these micro-algae as bioassessment indicators for monitoring river quality was quickly demonstrated. The objective of this review is to describe the state of the art of the study of diatoms and river pollution between 1999 and 2009. The objective was to group the publications homogeneously according to subject and to indicate which subjects never overlap. To this end a lexical analysis was conducted on the abstract structure of these publications and seven K-means clusters were defined. Most of the items in this area were found to have been published in Hydrobiologia. One group (group 6) comprises publications about a discipline (ecotoxicology); several others group publications on the basis of the same approaches, for example species (group 3), basin (group 7), or spatial approaches (group 2). Other publications are brought together because the studies used a common method of using data, namely predictive models (group 1) or biotic indices (group 4). One group of publications was of studies performed in the same area-South Africa (group 5). Several remarks can be made. First, ecotoxicological studies are mostly experimental and restricted to small study areas. To answer society's demand for new assessment tools for micropollutant assessment, the next step would be to have more in-situ tests on larger spatial scales. Second, diatom biomonitoring uses the word 'species' extensively, because this is the basis for establishing the lists of flora which are used extensively in such subject areas. Species is closely related to taxonomy; nevertheless this discipline is very rarely addressed in the papers. Third, phylogeny is never addressed in the publications. This is significant because phylogenetic studies for freshwater macroinvertebrates enable appropriate definition of taxonomic aggregations that can be used as accurate indicators of particular environmental stressors. [ABSTRACT FROM AUTHOR]

Autotrophic lakes are regarded to function as net autotrophic systems in which mobilization of solar energy by phytoplankton, benthic algae, and macrophytes forms the base of primary production. However, they are also subsided by allochthonous inputs. In this paper, we tested three hypotheses explaining the role of allochthonous subsidies as a driving force of autotrophic, bacterial, and heterotrophic production. The studies for this paper were conducted every fortnight from November 2015 to October 2017 in a small, shallow, temperate, eutrophic lake supplied with waters from four streams and drained by a single outlet. Changes in plankton biomass as well as variations in environmental conditions were estimated on the basis of the samples and measurements collected vertically in the water column (every 0.5 m depth) in the central part of the lake. Loads of nutrients and organic and inorganic matter were measured in both the inlets and the outlet of the lake, and on the basis of the differences between input and output loading, the amount of allochthonous subsidies in the lake was computed. Allochthonous subsidies affected the autotrophic production directly by supplying assimilable nutrients, and indirectly by providing allochthonous organic matter that supplemented the diet of omnivores and thus hampered their grazing pressure on phytoplankton. Bacterioplankton utilized allochthonous organic matter as well as effectively competed with phytoplankton for allochthonous nutrients. Dominant species of heterotrophic plankton were feeding opportunists, and thus inputs of allochthonous subsidies indubitably fostered high biomass of these species in the periods of low availability of autochthonous sources of food. Our finding suggests that allochthonous subsidies significantly affect trophic structure and impact both autotrophic and heterotrophic mobilization of energy through food chains in freshwater ecosystems. [ABSTRACT FROM AUTHOR]

Oil pollution entering the marine environment has been an issue of concern for many decades. It can come from riverine or land-based sources, accidental and intentional discharges from ships, or as a by-product of offshore oil extraction. Growing awareness of the impact of oil pollution on the marine environment has led, since the late 1960s, to the introduction of measures to reduce or eliminate pollution from shipping and the offshore oil industry. A framework for environmental protection of the North Sea has developed over many decades through international agreements, regional cooperation, and national measures, while education has also played an important role with modern-day sailors being given due training to understand that dumping waste at sea is illegal in many areas, and is harmful to the marine environment. This paper presents data on trends in pollution from ships and oil installations. While significant reductions in oil pollution have been identified over more than two decades, there remain some areas where action is needed to reduce inputs still further, especially from oil and gas platforms. This paper illustrates that international cooperation can result in a reduction in marine pollution leading to a cleaner environment. [ABSTRACT FROM AUTHOR]

Mouth gape sizes of marine finfish larvae determine the size of rotifer prey that can be ingested, so providing appropriate size rotifers controls the success of larval rearing. It is difficult for hatcheries to maintain pure cultures of multiple rotifer species by long-term serial dilution without cross-contamination. In this paper, we describe a technique for utilizing multiple rotifer species in larviculture that uses rotifer diapausing eggs as inocula, enabling hatcheries to supply larval predators with optimally sized rotifers. Biodiversity in the Brachionus plicatilis species complex is extensive, including considerable variation in body size. In this paper, we show that large quantities of diapausing eggs can be produced from many Brachionus species. Using the full range of body size diversity from seven Brachionus species, we can produce adult female rotifers with mean body lengths as small as 137 μM, or as large as 305 μM, and neonate females with body lengths ranging from 103 to 206 μM. The length of diapausing eggs for small Brachionus species averaged 100 μM, and 166 μM for large species. Diapausing egg production varied by 3.6 fold among 14 strains. Using diapausing eggs of the very small rotifer Proales similis (88 μM) to inoculate mass cultures also is described. [ABSTRACT FROM AUTHOR]

The invasion of dreissenid mussels into inland waters of the Northern Hemisphere has received considerable attention and, both zebra mussels and quagga mussels continue to spread westward. Despite studies aimed at understanding the biology of dreissenid mussels, relatively few studies have focused on water velocity and other hydrodynamic characteristics of water flow. The objective of this review was to identify, through a search of online databases, the papers that have been made available that directly have assessed the influence of hydrodynamic characteristics of water flow on dreissenid mussel biology. Using Thompson Reuters Web of Science, Google Scholar, and other resources, 46 papers were identified. These papers detailed that metrics associated with hydrodynamics of water flow, including current, wave action, velocity, flow rate, and discharge, can influence the biology of dreissenid mussels (primarily zebra mussel, which were studied far more than quagga mussel). Hydrodynamic characteristics influenced external fertilization, larval development and settlement, juvenile recruitment and attachment, and suspension feeding, growth and abundance of adults. In most cases, the impact of higher flow rates were locally negative and may present an opportunity for applications of water flow to control the spread or establishment of dreissenid mussels. Several knowledge gaps have been identified. [ABSTRACT FROM AUTHOR]

Establishing ecological assessment schemes is challenging when gradients are short and there are no sites with minimal anthropogenic alteration against which metrics can be calibrated. This is the situation for large rivers in Romania and this paper describes efforts to establish meaningful ecological status concepts. The intercalibration exercise, conducted as part of Water Framework Directive (WFD) implementation, has provided a metric ("phytobenthos Intercalibration Common Metric", pICM) which allows ecological status in different countries to be expressed on a common scale. The average boundary positions of countries who participated in this exercise provided a "common view" of status and, together with pICM, offer an "off-the-shelf" solution for countries unable to develop independent methods. However, even when expressed as pICM, Romanian phytobenthos data have a weak relationship with nutrients. Analysis of chemical data and comparison with similar data from elsewhere in Europe confirm that there are few sites with significantly elevated nutrient concentrations. Incorporation of the Romanian data into the larger dataset produced a stronger relationship from which the status of phytobenthos in very large rivers in Romania could be confirmed. This paper shows how the consensus that emerged from the WFD intercalibration exercise supports those countries unable to participate in the initial exercises. [ABSTRACT FROM AUTHOR]

Marine species possessing widely dispersing larvae are often considered to have open populations. However, two concepts are covered by the phrase ‚open population’. One concept stresses the supply of recruits from outside the local population (genetically open) while the alternative use describes situations where recruitment rate is independent of the local population size (demographically open). These two concepts are not necessarily equivalent. A review of recent literature suggests that there is no consensus on whether a demographic or genetic concept is associated with the use of the phrase ‚open population’. The different meanings of open population are never formally acknowledged. Explicit recognition of the different concepts of openness would remove an ambiguity from the literature and may aid communication between disciplines. Processes in natural populations, such as gregarious settlement and homing behaviour, are more clearly described by distinguishing between demographic and genetic degrees of openness. Changes in spatial scale will affect the degree of population openness. However, demographic and genetic aspects of population structure will not necessarily respond in the same ways to changes in scale. This provides further support for the explicit separation of genetic and demographic concepts of openness. [ABSTRACT FROM AUTHOR]

In species with complex life cycles, such as anuran amphibians, several traits are influenced by ecological factors during ontogeny. The anuran Physalaemus nattereri shows an aquatic spawning behavior, placing foam nests at the edges of a pond where the water contacts land, exposing tadpoles to dehydration once the pond dries. P. nattereri tadpoles are known to present an intermediate ability to survive out of water when compared to other species reproducing in permanent or temporary ponds. A decrease in size of tadpole tails has been suggested to represent a response to cope with dehydration stress, but might impair swimming performance. We investigated the effect of dehydration on morphological traits, focusing especially on tail proportions, as well as burst swimming speed. P. nattereri tadpoles were exposed to hydric stress on moist paper substrates and morphology and locomotor performance was compared within the same individuals before and after hydric stress. Our experiment showed that morphological changes induced by hydric stress were directly related to swimming performance. Individuals having smaller tails, due primarily to contractions of the medial to distal tail portions, exhibited reduced times to reach burst speed and reduced burst speeds. [ABSTRACT FROM AUTHOR]

Algae have been part of Chinese life for thousands of years. They are widely used as food and have been cited in Chinese literature as early as 2500 years ago. However, formal taxonomic studies on Chinese algae were initiated by foreign scientists only about 200 years ago, and by Chinese phycologists only about 90 years ago. This paper summarizes the history of modern phycological studies on Chinese algae and provides an overview of the achievements of phycological studies by Chinese scientists, especially on algal taxonomy, morphology, genetics, ecology and environmental research, physiology, biotechnology, algal culture, applied phycology and space phycology, in the last century. Recent development in phycological research focuses on algal floristic and molecular systematics, algal molecular biotechnology, applied phycology including micro and macroalgal cultivation and algal product development, and the roles of algae in environmental pollution control. These areas will also be the main focuses of Chinese phycological research in the foreseeable future. [ABSTRACT FROM AUTHOR]

This introductory paper presents 20 river restoration cases throughout Europe that were investigated in the EU-funded research project REFORM. In the following, this special issue provides seven specific papers that highlight and discuss the effects of restoration on the investigated river-floodplain systems. Additionally, restoration success was estimated from a socio-economic perspective. The first part of this paper presents the overall study concept and the general sampling design of the field investigations. Each study site was examined with the same array of methods, covering habitat composition in the river and its floodplain, three aquatic and two floodplain-related organism groups, as well as food web composition and 'aquatic terrestrial' interactions as reflected by stable isotopes. An overview of the rivers and the study sites summarizes main attributes of all investigated sites, with emphasis on the large-scale restoration projects. Some of the projects represent the 'state of the art' restoration approaches for two major European river types: gravel-bed mountain rivers and sand-bed lowland rivers. Concluding, restoration efforts had positive effects even in the small restoration projects investigated but did not increase with project size. No 'single best' measure could be identified, but river widening generally had a larger effect compared to other restoration measures. [ABSTRACT FROM AUTHOR]

Short-term zooplankton grazing experiments in bottles were conducted with water from 12 Danish brackish lakes covering a large gradient in salinity (0.3-17.4 ppt) as well as from mesocosms conducted in the same area with various salinities (0.5-12 ppt), two nutrient levels and low fish density (14). However, the ongoing climate change along with the already experienced extremes and a number of anthropogenic activities have increased their salinity at places and/or increased the amplitude of the salinity changes (Lengyel et al., [13]; B-Béres et al., [1]; Cortez et al., [5]). Also, in lentic environments of a drying coastal plain of Southeast Brazil, a comparison between stenohaline (i.e. narrow salinity tolerance ranges) and euryhaline (i.e. wide salinity tolerance ranges) fish species showed non-random patterns of community composition. Incubation under a range of salinities (5-57 ppt) indicated lower photosynthetic performance at increased salinity for both species, which increased their organic osmolyte contents with rising salinity stress. [Extracted from the article]

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

Sustainable global energy production is back-stopped by hydropower which is responsible for a significant share of the green energy produced worldwide. Hydropower, however, does not come without some environmental impacts but has worked to reduce those impacts. Here, we discuss the historical, legislative, and design configurations of hydropower facilities located in three of the world's most important producers: Brazil, Canada, and Norway. The background is intended to inform the collection of scientific papers from each country aimed at assessing and improving the sustainability of hydropower production that form the core of this special issue on sustainable hydropower. We review the development and key legislative history for hydropower in each country and point out the common backgrounds and interests each nation has in the continued sustainable development of its hydropower resources. [ABSTRACT FROM AUTHOR]

Hydropeaking refers to the mode of hydropower dam operation where sub-daily changes in flow are used to vary the generation of electricity in accordance with demand. A typical pattern produces maximum power during the day (i.e., the peak), and minimal power at night. Hydropeaking is considered necessary to stabilize the energy grid since it is the only reliably flexible method of producing electricity besides fossil fuels. With the planned phase-out of traditional coal-fired electricity production across Canada by 2030, and the increased reliance on intermittent wind and solar generation, the flexibility of hydropeaking will assume an increased importance. However, hydropower generation comes with costs; hydropeaking in particular is considered one of the most ecologically harmful modes of operation since downstream biota are subjected to flows that deviate greatly from typical natural flow regime patterns. The ecological effects of hydropeaking have been examined in a growing body of literature, but mitigation options do exist that include dam operational and/or structural modifications. This paper will explore the importance of hydropeaking in the Canadian electricity system, the ecological consequences of flexible hydropower, and mitigation options that could potentially strike a balance between meeting Canadian energy needs and minimizing ecosystem impacts. [ABSTRACT FROM AUTHOR]

In this paper, we investigated composition and trait turnover among fish assemblages in reservoirs distributed across major Brazilian basins, in order to contrast taxonomic and functional turnover and to investigate their respective drivers. We investigated the hypothesis that reservoir assemblages present, on a continental scale, divergent species compositions but with a similar set of traits. Species lists and functional traits were compiled from 79 reservoirs located in the Amazon, São Francisco, Paraná and Atlantic basins. We observed considerable variation in species and trait composition among reservoirs, with higher intra-basin similarity. Taxonomic turnover ranged between 0 and 1 (0.44 ± 0.22 SD), and functional turnover between 0 and 0.91 (0.37 ± 0.19); functional turnover correlated positively with taxonomic turnover, but showed lower values. Observed functional turnover values did not differ from null expectations, indicating lack of functional convergence. We detected significant effects of basin, longitude, latitude and elevation on turnover values, and the presence of non-native species was associated with either homogenization or differentiation patterns. Our results indicated that fish composition is heterogeneous among impoundments, providing little support to the hypothesis that reservoir assemblages are homogenized on a continental scale. Species and trait composition probably respond to multiple spatial, environmental and biogeographic factors. [ABSTRACT FROM AUTHOR]

The subterranean aquatic snails may serve as a model of endemism and isolation vs. migration in subterranean habitats. The aim of the present paper is to verify the hypothesis that subterranean aquatic snails can migrate through diverse subterranean habitats, applying four molecular markers as well as a RAPD technique and shell morphometry. They were used to estimate the differences and gene flow between populations of the hydrobiid subterranean aquatic species Montenegrospeum bogici, collected in the Dinaric karst region. Three molecularly distinct taxonomic units were distinguished. The mOTU B was found at single locality, mOTU C at two, but the mOTU A at ten localities, scattered along 236 km distance, at two of them in sympatry with either mOTU B or C. Within mOTU A, the estimated levels of the gene flow were high. The pairwise measures of genetic differentiation were statistically significantly associated with geographic distances between the populations. In general, neither the infinite-island model of interpopulation differentiation, expected for isolated populations, nor the stepping-stone one, but rather the isolation-by-distance model explained the observed pattern. Our results suggest that interstitial habitats provide ways of migration for the stygobiont M. bogici, as has been already suggested for other subterranean gastropods. [ABSTRACT FROM AUTHOR]

Increasing employment of artificial barriers to combat coastal erosion is causing alterations of coastal ecosystems. Understanding their ecological functioning is key to planning management activities and minimising their negative impacts on the ecosystem. In this paper, changes in biodiversity and in functional traits of macrofaunal shallow communities were investigated throughout 4 years of study in the central Mediterranean. Biodiversity indices (S, d, H′) showed the highest mean values during in-operam phases (5.7, 1.99 and 2.07, respectively) whilst functional diversity (FDis) and functional redundancy (FDiv/H′) showed the highest mean values in ante-operam (4.34 and 2.44, respectively). The PERMANOVA showed differences both in species composition and functional traits between sampling periods. β-diversity was driven by the replacement of species over years. The non-indigenous polychaete Lumbrinerides neogesae, recorded for the first time during in-operam, supplied the highest differences between years (14.5%, SIMPER). During in and post-operam phases an increase of sub-surface deposit feeder, tolerant, and pioneer categories was recorded. When the classic taxonomic approach is combined with novel functional biodiversity attributes, a wide range of biota responses to a disturbance can be better described and the efficient mitigation solutions to minimize negative impacts of human activities proposed. [ABSTRACT FROM AUTHOR]

This Special Issue on Crustacean Genomics arises from the TCS 2017 conference held in Barcelona, Spain, between 19 and 22 June, 2017. Applications of next generation sequencing have expanded rapidly over recent years, unveiling many new and exciting areas of genomic research. This includes novel insights into physiology, reproductive biology, response to environmental challenges, and their evolutionary history. Despite their importance, crustaceans still lack genomic resources compared with other widely-studied groups such as insects and vertebrates. The present volume integrates a collection of contributions from the speakers, and compiles the main results presented during the symposium. Following the structure of the Crustacean Genomics workshop, contributed papers have been arranged in two main blocks, a first set of studies focused on the use of transcriptomics to investigate crustacean physiology and reproduction while the second set focused on molecular systematics and evolutionary studies. [ABSTRACT FROM AUTHOR]

The present paper aims at reviewing general knowledge of large European perialpine lakes as provided by sediment studies, and at outlining the contribution, from several lines of evidence, of modern paleolimnology in both interpreting past lake ecological evolution and forecasting lake responses to future human impacts. A literature survey mainly based on papers published in international journals indexed on ISI-Wos and Scopus from 1975 to April 2017 has been conducted on the 20 perialpine lakes with zmax ≥ 100 m and lake area ≥ 10 km2, and on 4 shallower perialpine lakes representing hotspots of extensive neo- and paleo-limnological research. By pinpointing temporal and spatial differences in paleolimnological studies conducted in the Alpine countries, the review identifies knowledge gaps in the perialpine area, and shows how sediment-based reconstructions represent a powerful tool, in mutual support with limnological surveys, to help predicting future scenarios through the “past-forward” principle, which consists in reconstructing past lake responses to conditions comparable to those to come. The most recent methodological developments of sediment studies show the potential to cope with the increasing ecosystem variability induced by climate change, and to produce innovative and crucial information for tuning future management and sustainable use of Alpine waters. [ABSTRACT FROM AUTHOR]

Aquatic plants fulfil a wide range of ecological roles, and make a substantial contribution to the structure, function and service provision of aquatic ecosystems. Given their well-documented importance in aquatic ecosystems, research into aquatic plants continues to blossom. The 14th International Symposium on Aquatic Plants, held in Edinburgh in September 2015, brought together 120 delegates from 28 countries and six continents. This special issue of Hydrobiologia includes a select number of papers on aspects of aquatic plants, covering a wide range of species, systems and issues. In this paper, we present an overview of current trends and future directions in aquatic plant research in the early twenty first century. Our understanding of aquatic plant biology, the range of scientific issues being addressed and the range of techniques available to researchers have all arguably never been greater; however, substantial challenges exist to the conservation and management of both aquatic plants and the ecosystems in which they are found. The range of countries and continents represented by conference delegates and authors of papers in the special issue illustrates the global relevance of aquatic plant research in the early twenty first century but also the many challenges that this burgeoning scientific discipline must address. [ABSTRACT FROM AUTHOR]

Bivalves are ubiquitous members of freshwater ecosystems and responsible for important functions and services. The present paper revises freshwater bivalve diversity, conservation status and threats at the global scale and discusses future research needs and management actions. The diversity patterns are uneven across the globe with hotspots in the interior basin in the United States of America (USA), Central America, Indian subcontinent and Southeast Asia. Freshwater bivalves are affected by multiple threats that vary across the globe; however, pollution and natural system (habitat) modifications being consistently found as the most impacting. Freshwater bivalves are among the most threatened groups in the world with 40% of the species being near threatened, threatened or extinct, and among them the order Unionida is the most endangered. We suggest that global cooperation between scientists, managers, politicians and general public, and application of new technologies (new generation sequencing and remote sensing, among others) will strengthen the quality of studies on the natural history and conservation of freshwater bivalves. Finally, we introduce the articles published in this special issue of Hydrobiologia under the scope of the Second International Meeting on Biology and Conservation of Freshwater Bivalves held in 2015 in Buffalo, New York, USA. [ABSTRACT FROM AUTHOR]

Oreochromis cf. korogwe and Coptodon rendalli, two tilapiine fishes introduced to Lake Chala (Kenya/Tanzania) ~ 40 years ago, may negatively affect the endemic Chala tilapia (Oreochromis hunteri) by competition for food. However, the actual threat posed by the introduced cichlids cannot be assessed without data on the local feeding habits of all three species. This paper describes the diet of O. hunteri and both introduced species, focusing on seasonal changes in food-source availability. Microscopic analysis of gut content in 35 fishes collected over a 20-month period was compared with the composition of littoral food sources and seasonal variation in the limnetic phytoplankton and complemented with exploratory stable-isotope analysis of fish tissue. We found that all three tilapiines in Lake Chala are herbivorous, and during most of the year, they feed on algae and organic detritus on and between rocks in the littoral zone. However, in July–September they migrate to open water to feed on blooming phytoplankton. Interspecific differences in gut content and stable-isotope composition suggest that O. hunteri may have a competitive advantage over the two newcomers by making better use of this seasonal extra food resource. However, this advantage may erode when continuing climate change starts affecting the bloom's predictability. [ABSTRACT FROM AUTHOR]

The text is a preface to a special issue of the journal Hydrobiologia, titled "Trait-Based Approaches in Micro-Algal Ecology." The preface provides an overview of the 19th workshop of the International Association of Phytoplankton Taxonomy and Ecology (IAP), which focused on trait-based approaches in micro-algal ecology. The workshop brought together scientists and students from various countries to discuss ecological topics and practice species identification. The preface also mentions the history of the IAP workshops and the special issue's dedication to Colin S. Reynolds, a prominent phytoplankton ecologist. The special issue includes a selection of review and research papers covering a wide range of spatial and temporal scales and aquatic habitats. The authors express gratitude to the referees, editorial staff, and workshop participants. [Extracted from the article]