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

Author

Martins, Maria, Vandekerkhove, Jochen, Mezquita, Francesc, Schmit, Olivier, Rueda, Juan, Rossetti, Giampaolo, Namiotko, Tadeusz, Martins, Maria, Vandekerkhove, Jochen, Mezquita, Francesc, Schmit, Olivier, Rueda, Juan, Rossetti, Giampaolo, and Namiotko, Tadeusz

Abstract

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 diversity

Published
2018

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

Author

Martins, Maria, Vandekerkhove, Jochen, Adolfsson, Sofia, Rossetti, Giampaolo, Namiotko, Tadeusz, Jokela, Jukka, Martins, Maria, Vandekerkhove, Jochen, Adolfsson, Sofia, Rossetti, Giampaolo, Namiotko, Tadeusz, and Jokela, Jukka

Abstract

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 e

Published
2018

16. Database on environmental conditions and biodiversity in shallow lakes in Belgium and the Netherlands

Author

Lemmens, Pieter, primary, De Wever, Aaike, additional, Vandekerkhove, Jochen, additional, Muylaert, Koenraad, additional, Van der Gucht, Katleen, additional, Zwart, Gabriel, additional, Rommens, Wouter, additional, Van Wichelen, Jeroen, additional, Geenens, Vanessa, additional, Vyverman, Wim, additional, Brendonck, Luc, additional, Martens, Koen, additional, Declerck, Steven A.J., additional, and De Meester, Luc, additional

Published
2018
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17. Online Information Systems with Alien Species Occurrence Records in Europe: Coverage, Complementarity and Compatibility

Author

VANDEKERKHOVE JOCHEN and CARDOSO Ana

Abstract

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 resources

Published
2011

18. Alien Species and the Water Framework Directive - Questionnaire Results

Author

VANDEKERKHOVE JOCHEN and CARDOSO Ana

Abstract

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 resources

Published
2010

25. EVALUATION OF ELEVATED PLOIDY AND ASEXUAL REPRODUCTION AS ALTERNATIVE EXPLANATIONS FOR GEOGRAPHIC PARTHENOGENESIS IN EUCYPRIS VIRENS OSTRACODS

Author

Adolfsson, Sofia, primary, Michalakis, Yannis, additional, Paczesniak, Dorota, additional, Bode, Saskia N. S., additional, Butlin, Roger K., additional, Lamatsch, Dunja K., additional, Martins, Maria J. F., additional, Schmit, Olivier, additional, Vandekerkhove, Jochen, additional, and Jokela, Jukka, additional

Published
2009
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28. The importance of drawdown and sediment removal for the restoration of the eutrophied shallow Lake Kraenepoel (Belgium)

Author

Van Wichelen, Jeroen, primary, Declerck, Steven, additional, Muylaert, Koenraad, additional, Hoste, Ivan, additional, Geenens, Vanessa, additional, Vandekerkhove, Jochen, additional, Michels, Erik, additional, De Pauw, Niels, additional, Hoffmann, Maurice, additional, De Meester, Luc, additional, and Vyverman, Wim, additional

Published
2007
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36. The importance of drawdown and sediment removal for the restoration of the eutrophied shallow lake Kraenepoel (Belgium).

Author

Martens, K., Gulati, Ramesh D., Lammens, Eddy, Van Donk, Ellen, Van Wichelen, Jeroen, Declerck, Steven, Muylaert, Koenraad, Hoste, Ivan, Geenens, Vanessa, Vandekerkhove, Jochen, Michels, Erik, De Pauw, Niels, Hoffmann, Maurice, De Meester, Luc, and Vyverman, Wim

Abstract

Lake Kraenepoel (Belgium) is a shallow lake (22 ha), divided in two basins since 1957 by a shallow dike. The lake was used for fish farming until World War II and was drawn down about every 5 years to harvest fish. Despite its dense historical carp population, it had clear water and a rich Littorelletea vegetation. During the course of the 20th century, the lake became eutrophic and the Littorelletea vegetation degraded. The northern basin, which was still drawn down about every decade after 1957, retained its clear water and had a dense submerged macrophyte vegetation. The southern basin, which was never drawn down after 1957 and which received direct surface water inputs, had become a turbid shallow lake with phytoplankton blooms in summer. In 2000, efforts were taken to restore the lake: the entire lake was drawn down, the fish community was biomanipulated, nutrient-rich surface water inputs were diverted from the southern basin and sediments were removed (only in the northern basin). Fish biomanipulation and sediment removal were successful in the northern basin, as nutrient levels declined and the Littorelletea vegetation recovered. In the southern basin, sediment analyses indicated that drawdown resulted in sediments with a lower water and organic matter content and water column turbidity decreased after the drawdown. But pH in the southern basin declined to <4, probably because sulphides in the sediment were oxidized during drawdown and sediment desiccation. In contrast, desiccated sediments were removed from the northern basin and pH did not decline below 6 after restoration. In spite of the still high dissolved nutrient concentrations, phytoplankton biomass declined significantly in the southern basin, probably due to acidification. However, no Littorelletea species colonised the lake bottom in the southern basin. Thus, lake drawdown may be a useful management technique to promote clear water conditions in shallow lakes. However, acidification due to sulphide oxidation may be an undesirable outcome and should be considered in drawdown and sediment desiccation manipulations. [ABSTRACT FROM AUTHOR]

Published
2007
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37. The importance of drawdown and sediment removal for the restoration of the eutrophied shallow Lake Kraenepoel (Belgium).

Author

Wichelen, Jeroen, Declerck, Steven, Muylaert, Koenraad, Hoste, Ivan, Geenens, Vanessa, Vandekerkhove, Jochen, Michels, Erik, Pauw, Niels, Hoffmann, Maurice, Meester, Luc, and Vyverman, Wim

Subjects
LAKES, LAKE ecology, AGRICULTURE & the environment, FISH farming, FISH population thinning, EUTROPHICATION control, BIOMANIPULATION, NUTRIENT pollution of water, PLANTAGINACEAE, CARP fisheries
Abstract

Lake Kraenepoel (Belgium) is a shallow lake (22 ha), divided in two basins since 1957 by a shallow dike. The lake was used for fish farming until World War II and was drawn down about every 5 years to harvest fish. Despite its dense historical carp population, it had clear water and a rich Littorelletea vegetation. During the course of the 20th century, the lake became eutrophic and the Littorelletea vegetation degraded. The northern basin, which was still drawn down about every decade after 1957, retained its clear water and had a dense submerged macrophyte vegetation. The southern basin, which was never drawn down after 1957 and which received direct surface water inputs, had become a turbid shallow lake with phytoplankton blooms in summer. In 2000, efforts were taken to restore the lake: the entire lake was drawn down, the fish community was biomanipulated, nutrient-rich surface water inputs were diverted from the southern basin and sediments were removed (only in the northern basin). Fish biomanipulation and sediment removal were successful in the northern basin, as nutrient levels declined and the Littorelletea vegetation recovered. In the southern basin, sediment analyses indicated that drawdown resulted in sediments with a lower water and organic matter content and water column turbidity decreased after the drawdown. But pH in the southern basin declined to <4, probably because sulphides in the sediment were oxidized during drawdown and sediment desiccation. In contrast, desiccated sediments were removed from the northern basin and pH did not decline below 6 after restoration. In spite of the still high dissolved nutrient concentrations, phytoplankton biomass declined significantly in the southern basin, probably due to acidification. However, no Littorelletea species colonised the lake bottom in the southern basin. Thus, lake drawdown may be a useful management technique to promote clear water conditions in shallow lakes. However, acidification due to sulphide oxidation may be an undesirable outcome and should be considered in drawdown and sediment desiccation manipulations. [ABSTRACT FROM AUTHOR]

Published
2007
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40. Dynamics of sexual and parthenogenetic populations of Eucypris virens (Crustacea: Ostracoda) in three temporary ponds

Author

Martins, Maria, Vandekerkhove, Jochen, Mezquita, Francesc, Schmit, Olivier, Rueda, Juan, Rossetti, Giampaolo, Namiotko, Tadeusz, Martins, Maria, Vandekerkhove, Jochen, Mezquita, Francesc, Schmit, Olivier, Rueda, Juan, Rossetti, Giampaolo, and Namiotko, Tadeusz

Abstract

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 diversity

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

Author

Martins, Maria, Vandekerkhove, Jochen, Adolfsson, Sofia, Rossetti, Giampaolo, Namiotko, Tadeusz, Jokela, Jukka, Martins, Maria, Vandekerkhove, Jochen, Adolfsson, Sofia, Rossetti, Giampaolo, Namiotko, Tadeusz, and Jokela, Jukka

Abstract

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 e

42. Extreme tolerance to environmental stress of sexual and parthenogenetic resting eggs of Eucypris virens (Crustacea, Ostracoda).

Author

VANDEKERKHOVE, JOCHEN, MARTENS, KOEN, ROSSETTI, GIAMPAOLO, MESQUITA‐JOANES, FRANCESC, and NAMIOTKO, TADEUSZ

Subjects
*CRUSTACEAN reproduction, *OSTRACODA, *FRESHWATER animals, *ASEXUAL reproduction, *HYDRATION, *DIGESTIVE enzymes, *PHYSIOLOGICAL effects of radiation
Abstract

1. The freshwater ostracod (Ostracoda), Eucypris virens, is commonly found in European temporary pools, where its long-term persistence completely relies on the build-up of resting egg banks. Extreme tolerance of dormant eggs and seeds is widely assumed, but freshwater ostracod eggs are relatively poorly studied. The study of ostracod resting eggs is of particular relevance as it may yield the key to understanding the distribution of the sexes in many species capable of both sexual and asexual reproduction. 2. We assessed the tolerance of dried resting eggs produced by females originating from three populations with males and three all-female E. virens populations. Hatching time and success was compared between control eggs and eggs exposed to one of seven ecologically relevant stressors: digestive enzymes, high salinity, deep freezing, hydration, UV-B radiation, hypoxia and insecticide treatment. 3. None of the stressors reduced significantly the viability of either sexual or asexual eggs. When compared with the reproductive mode-specific controls, exposure to UV-B radiation had a mild impact on the survival of sexual and asexual eggs (−16.8 and −22.4%, respectively), but this was only significant for asexual eggs. These results point to an extreme tolerance of E. virens resting eggs and have important implications for the ecology and evolution of the species. 4. The timing of hatching was not affected by the stress treatment, except for UV-B radiation. A marginally significant delay in hatching response was observed for UV-B-radiated eggs when compared to the overall mean, but this treatment effect was absent when compared with the reproductive mode-specific controls. 5. The populations with males produced eggs that hatched on average earlier (−1.5 days at 17 °C) and were more successful (+26%) than asexual eggs. Due to the limited number of populations and the population-specific origin and age of the eggs, the possibility due to the differences in age and origin of the resting eggs, or to variations in local conditions, cannot be ruled out. [ABSTRACT FROM AUTHOR]

Published
2013
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