Alien Species and the Water Framework Directive - Questionnaire Results

Alien species constitute a major pressure in aquatic environments, both ecologically and economically. This recognition has initiated a debate on the role of alien species in ecological status classifications. We distributed a questionnaire to review how EU Member States (MSs) deal with alien species in their national status assessments under the Water Framework Directive (WFD). The questionnaire was filled and returned by 23 EU MSs and Norway. Analysis of the questionnaire returns and referred methods revealed the existence of a wide range of approaches: (1) The majority of MSs do not take alien species explicitly into account for classification under the WFD. This implies that the biological methods that were developed for assessing anthropogenic pressures are assumed to be able to pick up pressures by alien species, but this remains to be verified. Some of these MSs do acknowledge the need for a more direct or supplementary account of alien species, but fail to do so because of the lack of information on the impact and distribution of alien species within their territory. (2) Few MSs assess ecological status using the pressure-based tools, and subsequently downgraded the status in case of presence of predefined high-impact alien species. The main critiques to this approach are that it puts too much weight on alien species, compared to other pressures, and that it may results in downgrading of many water bodies, even in the absence of any perspectives for remediation of the problem. (3) Others account for alien species by attributing aliens a different score than native species in a metric, or by including alien species in comparisons with alien-free reference communities. Such approaches may blur the impact assessment of other pressures, and may obscure the magnitude of the alien species problem. (4) Almost all MSs support the idea of a supplementary biopollution index. Such an index would uncouple alien species and anthropogenic pressure assessments, and allow for a correct appraisal of the problem without affecting the WFD classification. A pan-European index may not be feasible because of different trade-offs between practicability and accuracy across MSs. A better harmonization of the views on alien species and water body classification within Europe is desirable, but a challenging task. It requires an agreed interpretation and usage of alien species related terms, and an increased compatibility and completeness of national and regional alien species lists. These topics have been added for discussion to the 2010-2012 mandate of the WFD Working Group on Ecological Status.JRC.DDG.H.5-Rural, water and ecosystem resource

Online Information Systems with Alien Species Occurrence Records in Europe: Coverage, Complementarity and Compatibility

This report assesses the coverage of thirty existing on-line national, regional and global databases from which alien species occurrence records within the territory of the European Union can be retrieved. In addition, it quantifies their degree of complementarity, and as such the added value of an integrated information system. Finally, it includes a qualitative evaluation of the feasibility of combining alien species information from existing databases at EU level. Our comparative analysis of occurrence data across 30 online databases with alien species records uncovers a high degree of complementarity of information. The most comprehensive resource for country level alien species occurrences in Europe (DAISIE) fails to report about one out of every four species known to be alien to one or more countries within the EU27 + Norway territory. When accessing only a single database, a minimum of 10,000 species by country records stay unaccounted for at European level. The distributed and largely independent nature of existing alien species information systems has multiple consequences: (i) In the absence of an overarching data exploration system, it complicates the retrieval of information, and the identification of knowledge gaps; (ii) It allows systems to diverge and as such become less compatible; (iii) It potentially makes inefficient use of existing financial and intellectual resources. The efficiency and accuracy of existing databases could be improved if communication between systems was enhanced. Expert knowledge could be shared and harmonization of the information would facilitate the retrieval of information, for example through a common network of interoperable web services. Integrated alien species databases currently report occurrences at country level, with limited value for scientists and managers. A shift towards georeferenced occurrences could be achieved in a cost-effective way by link linking to biodiversity databases and digitized archives of relevant journals.JRC.DDG.H.5-Rural, water and ecosystem resource

Effect of environmental stress on clonal structure of Eucypris virens (Crustacea, Ostracoda)

Environmental stress imposes strong natural selection on clonal populations, promoting evolutionary change in clonal structure. Environmental stress may also lead to reduction in population size, which together with clonal selection may reduce genotypic diversity of the local populations. We examined how clonal structure in wild-collected samples of two parthenogenetic populations of the freshwater ostracod Eucypris virens responded to hypersalinity and starvation, and the combination of the two stressors. We applied the stress treatments in a factorial design for one generation. When 60% of the individuals per experimental unit had died, post-experimental clonal structure was compared to that of the start of the experiment, which reflected the field conditions. We used five polymorphic allozyme loci as genotype markers. All stress treatments reduced survival compared to the control treatment. In the population "Rivalazzetto”, we observed a reduction of clonal richness in the control treatment, with the initially dominant clone maintaining dominance. This may have resulted from interclonal competition and clone-specific survival under the different laboratory conditions. Clonal richness remained high in the salinity treatment while it was reduced in the combined stress and starvation treatments. In the population "Fornovo”, clonal richness reduced in all treatments including control, while the salinity and combined stress treatment reduced clonal evenness. The clone dominating at the start of the experiment increased in frequency in all treatments, but the change in clonal structure during the experiment was more pronounced in this population. These results suggest that in some conditions an intermediate level of environmental stress may lessen the decline in genetic diversity by strong inter-clonal competition. Moreover, the variation in clonal structure among the stress treatments and distinct genetic backgrounds indicates that more general predictions of stress effects on clonal structure may be difficul

Building the European Alien Species Information Network (EASIN): a novel approach for the exploration of distributed alien species data

The European Alien Species Information Network (EASIN; http://easin.jrc.ec.europa.eu) aims to facilitate the exploration of existing alien species information from distributed sources through a network of interoperable web services, and to assist the implementation of European policies on biological invasions. The network allows extraction of alien species information from online information systems for all species included in the EASIN catalogue. This catalogue was based on an inventory of reported alien species in Europe that was produced by reviewing and standardizing information from 43 online databases. It includes information on taxonomy, synonyms, common names, pathways of introduction, native range in Europe, and impact. EASIN catalogue entails the basic information needed to efficiently link to existing online databases and retrieve spatial information for alien species distribution in Europe. Using search functionality powered by a widget framework, it is possible to make a tailored selection of a subgroup of species based on various criteria (e.g., environment, taxonomy, pathways). Distribution maps of the selected species can be produced dynamically and downloaded by the user. The EASIN web tools and services follow internationally recognized standards and protocols, and can be utilized freely and independently by any website, while ownership of the data remains with its source, which is properly cited and linked.JRC.H.1-Water Resource

Dynamics of sexual and parthenogenetic populations of Eucypris virens (Crustacea: Ostracoda) in three temporary ponds

Eucyprisvirens is a freshwater ostracod in which both sexual reproduction and parthenogenesis occur. Sympatric coexistence of both reproductive modes is known in zones of overlap. This renders the species a potentially valuable model organism to study the ‘queen of evolutionary problems', i.e. why sex is so successful despite its costs (paradox of sex). In order to maximally exploit this potential, a broad knowledge of the species' ecology is essential, including an understanding of its life history and population dynamics. Here, the phenology of the species was followed in three temporary ponds through monthly (Spain) or fortnightly (Poland) samplings, throughout an inundation period. This study confirms the wide ecological tolerances of E.virens. Although the species is generally assumed to be univoltine, two hatching periods were observed in the Spanish sites. Biotic interactions, especially predation, appear to be the important determinants of population dynamics in long-hydroperiod sites. Abiotic conditions may influence population dynamics through their impact on egg hatching. In the site with male presence, the initially female-biased sex ratio evolved towards a balanced sex ratio through the season. No consistent differences in limb morphology were observed between females originating from the three study sites. On the other hand, valve size of adult females varied among sites, possibly influenced by local environmental conditions (mainly salinity and pH) as well as the expected genetic diversit

Pyriproxyfen, a juvenoid hormone analog, does not induce male production in parthenogenetic lineages of Eucypris virens (Crustacea: Ostracoda)

Analogs of juvenoid hormones are increasingly recommended for controlling insect pests in agriculture. One of these analogs, pyriproxyfen, was found to be very potent in inducing male production in Daphnia under laboratory conditions, even after acute exposure. Other studies also demonstrated a major role of juvenoid hormones for the sex determination in arthropods that have sex chromosomes. We exposed parthenogenetic lineages of the freshwater ostracod Eucypris virens to a wide range of pyriproxyfen concentrations, and compared mortality and fecundity between treated and control animals. Animals exposed to the highest concentrations of pyriproxyfen (3-30 nM) experienced a higher mortality than control animals, but no treatment effects were found on the production rates of eggs and hatchlings. Also, hatchlings that emerged from eggs deposited by treated individuals did not suffer from an increased mortality rate. No males were found among the 91 hatchlings that could be grown to adulthood. These results suggest that previous observations of a reduced population growth of ostracods in treated field crops might not be due to an alteration of the sex ratio, but rather to an increased mortality of the exposed females

Data from: Sex in an uncertain world: environmental stochasticity helps restore competitive balance between sexually and asexually reproducing populations

Like many organisms, individuals of the freshwater ostracod species Eucypris virens can have either obligate sexual or asexual reproductive modes. Both types of individual routinely co-occur, including in the same temporary freshwater pond (their natural habitat in which they undergo seasonal diapause). Given the well-known two-fold cost of sex, this begs the question of how sexually reproducing individuals are able to co-exist with their asexual counterparts in spite of such overwhelming costs. Environmental stochasticity in the form of “false dawn” inundations (where the first hydration is ephemeral and causes loss of early hatching individuals) may provide an advantage to the sexual subpopulation, which exhibits greater variation in hatching times following inundation. We explore the potential role of environmental stochasticity in this system using life-history data analysis, climate data and matrix projection models. In the absence of environmental stochasticity, the population growth rate is significantly lower in sexual subpopulations. Climate data reveal that “false dawn” inundations are common. Using matrix projection modeling with and without environmental stochasticity, we demonstrate that this phenomenon can restore appreciable balance to the system, in terms of growth rates. This provides support for the role of environmental stochasticity in helping to explain the maintenance of sex and the occurrence of geographic parthenogenesis

Evaluation of online information sources on alien species in Europe - the need of harmonization and integration

Europe is severely affected by alien invasions, which impact biodiversity, ecosystem services, economy, and human health. A large number of national, regional, and global online databases provide information on the distribution, pathways of introduction, and impacts of alien species. The sufficiency and efficiency of the current online information systems to assist the European policy on alien species was investigated by a comparative analysis of occurrence data across 43 online databases. Large differences among databases were found which are partially explained by variations in their taxonomical, environmental, and geographical scopes but also by the variable efforts for continuous updates and by inconsistencies on the definition of ‘‘alien’’ or ‘‘invasive’’ species. No single database covered all European environments, countries, and taxonomic groups. In many European countries national databases do not exist, which greatly affects the quality of reported information. To be operational and useful to scientists, managers, and policy makers, online information systems need to be regularly updated through continuous monitoring on a country or regional level. We propose the creation of a network of online interoperable web services through which information in distributed resources can be accessed, aggregated and then used for reporting and further analysis at different geographical and political scales, as an efficient approach to increase the accessibility of information. Harmonization, standardization, conformity on international standards for nomenclature, and agreement on common definitions of alien and invasive species are among the necessary prerequisites.JRC.H.1-Water Resource

ostracod life history

Ontogenetic survivorship and stage duration for Eucypris virens individuals as described in the associated article