Publications

habitat-dependent hybrid parentage and differential introgression between neighboringly sympatric daphnia species.	allozyme, morphological, and pcr-generated mtdna markers were used to analyze hybrid parentage and introgression between the neighboringly sympatric crustaceans daphnia galeata mendotae and daphnia rosea. mtdna analysis of d. galeata mendotae from 15 lakes and of d. rosea from 8 lakes revealed species-specific fragment patterns resulting from taqi and rsai digestion. no individuals of one parent species possessed the typical mtdna of the other parent species, suggesting that mtdna introgression ...	1993	8346220
phylogenetics and evolution of the daphnia longispina group (crustacea) based on 12s rdna sequence and allozyme variation.	although members of the crustacean genus daphnia have been the target of much research, there is little understanding of the group's evolutionary history. we addressed this gap by inferring a phylogeny for one of the major species groups (longispina) using nucleotide sequence variation of a 525-bp segment of the mitochondrial 12s rdna and allozyme variation at 21 loci. we identified the major lineages and their relationships, assessed the phylogenetic utility of the few morphological characters ...	1996	8744763
role of microcystins in poisoning and food ingestion inhibition of daphnia galeata caused by the cyanobacterium microcystis aeruginosa.	the effects of microcystins on daphnia galeata, a typical filter-feeding grazer in eutrophic lakes, were investigated. to do this, the microcystin-producing wild-type strain microcystis aeruginosa pcc7806 was compared with a mcy- pcc7806 mutant, which could not synthesize any variant of microcystin due to mutation of a microcystin synthetase gene. the wild-type strain was found to be poisonous to d. galeata, whereas the mcy- mutant did not have any lethal effect on the animals. both variants of ...	1999	9925609
behaviour plasticity without learning: phenotypic and genetic variation of naïve daphnia in an ecological trade-off.	the swimming behaviour of adult daphnia largely governs their depth, which has a direct effect on both individual foraging success and predation avoidance. we treated individual swimming behaviour as a threshold character and used directional changes in average clonal depth within experimental tubes as a test for character plasticity. we compared the swimming behaviours of two cohabiting, phenotypically similar daphnia (daphnia galeata and daphnia galeata-daphnia rosea hybrid) to determine (1) w ...	2000	10860520
natural selection for grazer resistance to toxic cyanobacteria: evolution of phenotypic plasticity?	we studied the selection response of the freshwater grazing zooplankter, daphnia galeata, to increased abundance of cyanobacteria in its environment. cyanobacteria are a poor-quality and often toxic food. distinct genotypes of d. galeata were hatched from diapausing eggs extracted from three time horizons in the sediments of lake constance, europe, covering the period 1962 to 1997, a time of change in both the prevalence of planktonic cyanobacteria and levels of phosphorus pollution. we assessed ...	2001	11794781
a spontaneous mutant of microcystin biosynthesis: genetic characterization and effect on daphnia.	microcystis aeruginosa strain mrc is unique in its' possession of the mcya-j gene cluster, which encodes microcystin synthetase, but its' inability to produce microcystins. m. aeruginosa strain mrd is genetically identical to mrc at numerous genomic loci examined, but produces a variety of microcystins, mainly with the amino acid tyrosine in the molecule. zooplankton studies with daphnia galeata and d. pulicaria, using the mutant (mrc) and its' wild type (mrd), showed for the first time that mic ...	2001	11846757
[molecular genetic diagnostics of some daphnia species (crustacea, cladocera) from the volga river].	population genetic structure of the widespread daphnia species from kuibyshev and saratov reservoirs was examined by use of rapd-pcr technique with four mitochondrial dna (16s rrna) specific primers. one of the examined daphnia clones from the volga region appeared to be conspecific to the north american daphnia galeata, while another clone was most likely a hybrid between d. galeata and d. cucullata.	2003	12722646
absence of sterols constrains carbon transfer between cyanobacteria and a freshwater herbivore (daphnia galeata).	a key process in freshwater plankton food webs is the regulation of the efficiency of energy and material transfer. cyanobacterial carbon (c) in particular is transferred very inefficiently to herbivorous zooplankton, which leads to a decoupling of primary and secondary production and the accumulation of cyanobacterial biomass, which is associated with reduced recreational quality of water bodies and hazards to human health. a recent correlative field study suggested that the low transfer effici ...	2003	12816661
effects of the organophosphorus insecticide fenthion on phyto- and zooplankton communities in experimental ponds.	the organophosphorus insecticide fenthion was applied to experimental ponds and its effects on phyto- and zooplankton communities were analysed. the sensitivity to fenthion differed among cladoceran and rotiferan species according to the following order: daphnia galeata > monia micrura > bosmina fatalis >/= polyarthra trigla > keratella valga. the results suggest that large zooplankton species tend to be more sensitive to fenthion than small ones, large cladocerans more sensitive than small clad ...	1995	15091541
effects of repeated application of carbaryl on zooplankton communities in experimental ponds with or without the predator chaoborus.	zooplankton communities with or without chaoborus larvae were established in outdoor experimental ponds, to which the insecticide carbaryl was applied repeatedly at 10 or 100 microg litre(-1). in the ponds without chaoborus, cladocera dominated, but the species composition differed among the treatments. a large-sized cladocera daphnia galeata dominated the controls, the medium-sized cladocerans diaphanosoma brachyurum and moina micrura became dominant in the low-dose treatment, and the small-siz ...	1991	15092058
aluminum binding to ion exchange sites in acid-sensitive versus acid-tolerant cladocerans.	two acid-sensitive cladocerans, daphnia galeata mendotae and d. retrocurva, and one acid-tolerant one, bosmina longirostris, were exposed for 24 h to ph 5.0 and 200 microg liter(-1) total al. the entire procedure was replicated on three dates in summer 1989. mortality rates were determined, and the extent of al binding to ion exchange sites determined using hematoxylin staining. both daphnids consistently experienced near 100% mortalities, while mortalities for b. longirostris were always near z ...	1990	15092298
impact of 10 dietary sterols on growth and reproduction of daphnia galeata.	in crustaceans, cholesterol is an essential nutrient, which they must directly obtain from their food or by bioconversion from other dietary sterols. eukaryotic phytoplankton contain a great variety of sterols that differ from cholesterol in having additional substituents or different positions and/or number of double bonds in the side chain or in the sterol nucleus. in this study, we investigated to what extent these structural features affect the growth and reproduction of daphnia galeata in s ...	2004	15139303
life history consequences of sterol availability in the aquatic keystone species daphnia.	the absence of essential biochemical nutrients, such as polyunsaturated fatty acids or sterols, has been considered as a mechanism determining trophic interactions between the herbivore daphnia and its phytoplankton food source. here, we experimentally quantify the sensitivity of two daphnia species to decreasing amounts of dietary sterols by measuring variations in life history traits. the two species daphnia magna and d. galeata were fed different mixtures of the sterol-containing green alga s ...	2005	15891820
distribution of microcystins in a lake foodweb: no evidence for biomagnification.	microcystins, toxins produced by cyanobacteria, may play a role in fish kills, although their specific contribution remains unclear. a better understanding of the eco-toxicological effects of microcystins is hampered by a lack of analyses at different trophic levels in lake foodwebs. we present 3 years of monitoring data, and directly compare the transfer of microcystin in the foodweb starting with the uptake of (toxic) cyanobacteria by two different filter feeders: the cladoceran daphnia galeat ...	2005	16052377
comparing grazing on lake seston by dreissena and daphnia: lessons for biomanipulation.	biomanipulation measures in lakes, taken to diminish algal blooms, have mainly been restricted to the reduction of zooplanktivorous fish with the aim to stimulate the grazing pressure by native filter feeders such as daphnia. however, larger filter feeders like the exotic zebra mussel, dreissena polymorpha, have been suggested as an optional tool because of their high filtering capacity. we compared grazing by two filter feeders, d. polymorpha and daphnia galeata, offered seston from lake ijssel ...	2005	16184335
population oscillations and energy reserves in planktonic cladocera and their consequences to competition.	time lags in an individual's response to decreased food densities are responsible for oscillations in laboratory populations of daphnia galeata mendotae. visible energy reserves of triacylglycerols accumulate in the body of animals at low population densities when food is abundant and are later metabolized at high population densities when food is scarce to temporarily sustain activity and reproduction. after these energy reserves are metabolized many individuals, primarily juveniles, starve and ...	1980	16592788
persistence of host and parasite populations subject to experimental size-selective removal.	predators have the potential to limit the spread of pathogens not only by selecting infected prey but also by shaping prey demographics. we tested this idea with an epidemiological experiment in which we simulated variable levels of size-selective predation on zooplankton hosts and monitored the persistence of host and parasite populations. in the absence of simulated predation, the virulent protozoan caullerya mesnili frequently drove its host daphnia galeata to extinction. uninfected control p ...	2006	16685511
protection against the toxicity of microcystin-lr and cylindrospermopsin in artemia salina and daphnia spp. by pre-treatment with cyanobacterial lipopolysaccharide (lps).	purified cyanobacterial lipopolysaccharide (lps) was not acutely toxic to three aquatic invertebrates (artemia salina, daphnia magna and daphnia galeata) in immersion trials. however, pre-exposure (24 h) to 2 ngml(-1) lps increased the lc(50) of microcystin-lr significantly in all 3 species. similar results were observed with a. salina pre-treated with the same concentration of cyanobacterial lps and subsequently exposed to cylindrospermopsin, increasing the lc(50) by 8. the findings indicate th ...	2006	16982077
climate-driven warming during spring destabilises a daphnia population: a mechanistic food web approach.	temperature-driven changes in interactions between populations are crucial to the estimation of the impact of global warming on aquatic food webs. we analysed inter-annual variability in two data sets from bautzen reservoir, germany. in a long-term data set (1981-1999) we examined the pelagic phenology of daphnia galeata, a keystone species, the invertebrate predator leptodora kindtii, phytoplankton and secchi depth in relation to water temperature and the north atlantic oscillation index. in a ...	2007	17120058
spatial, environmental and anthropogenic effects on the taxon composition of hybridizing daphnia.	the competitive ability of hybrids, compared with their parental taxa, can cover a wide fitness range from poor to superior. for example communities of the daphnia galeata-hyalina-cucullata species complex often show hybrid dominance. we tested whether taxa composition of 43 european lakes inhabited by this species complex can be explained by habitat characteristics (e.g. size descriptors, trophy level) or geography. we found that d. galeata occurs more frequently south of the alps, whereas d. h ...	2008	18508753
daphnia hybridization along ecological gradients in pelagic environments: the potential for the presence of hybrid zones in plankton.	the relative homogeneity of pelagic environments has been regarded as the reason for the absence of hybrid zones for hybridizing planktonic daphnia (crustacea: cladocera); occasional dominance of interspecific hybrids over parental species was explained by their temporal superiority in fluctuating environments. however, water bodies with spatially varying environmental conditions might facilitate the formation of hybrid zones in plankton. we studied the distribution of species and hybrids of the ...	2008	18508758
prior residency does not always pay off--co-infections in daphnia.	the epidemiological and ecological processes which govern the success of multiple-species co-infections are as yet unresolved. here we investigated prior versus late residency within hosts, meaning which parasite contacts the host first, to determine if the outcomes of intra-host competition are altered. we infected a single genotype of the waterflea daphnia galeata with both the intestinal protozoan caullerya mesnili and the haemolymph fungus metschnikowia sp. (single genotype of each parasite ...	2010	20444300
potential synergistic effects of microcystins and bacterial lipopolysaccharides on life history traits of daphnia galeata raised on low and high food levels.	metastudies have found no consistent effects of the cyanobacterial toxin microcystin on daphnia, and there are discrepancies between field observations and experiments. confounding factors include absence or presence of alternative high quality food or the presence of bioactive compounds, other than microcystins in cyanobacteria. of specific interest are lipopolysaccharides (lps) on the outer cell wall. lps may have a number of biological effects, including reduced detoxication of microcystins i ...	2011	21635866
acute and chronic toxicity of benzotriazoles to aquatic organisms.	purpose: resulting from their intensive use as corrosion inhibitors in aircraft deicing and anti-icing fluids (adaf) and for silver protection in dishwasher detergents benzotriazoles (bts) are widespread in european surface waters. the current study aimed on an ecotoxicological characterization of 1h-benzotriazole (1h-bt) and 5-methyl-1h-benzotriazole (5mbt). methods: acute and chronic oecd guideline tests were c ...	2011	22203403
discrimination of hybrid classes using cross-species amplification of microsatellite loci: methodological challenges and solutions in daphnia.	microsatellite markers are important tools in population, conservation and forensic studies and are frequently used for species delineation, the detection of hybridization and introgression. therefore, marker sets that amplify variable dna regions in two species are required; however, cross-species amplification is often difficult, as genotyping errors such as null alleles may occur. to estimate the level of potential misidentifications based on genotyping errors, we compared the occurrence of p ...	2012	22487563
modes and mechanisms of a daphnia invasion.	whether exotic species invade new habitats successfully depends on (i) a change in the invaded habitat that makes it suitable for the invader and (ii) a genetic change in the invading taxon that enhances its fitness in the new habitat, or both. we dissect the causes of invasions of swiss lakes, north of the alps, by daphnia galeata (a zooplankter typical of eutrophic lakes, e.g. those south of the alps, which are also warmer) by comparing the fitness performance of eight geographically distribut ...	2012	22513861
survivals of d. galeata in sub-tropical reservoirs: harmful effects of toxic cyanobacteria in food source.	in the present study, we tested the hypothesis that massive occurrence of cyanobacteria as food source is one of the factors limiting the distribution of the zooplankton daphnia galeata in the warm water reservoirs of south china. d. galeata was fed with chlorella pyrenoidosa, 4 strains of cyanobacteria (three strains of microcystis aeruginosa: mc1, mc2 and mc3, and one strain of pseudoanabaena sp. :pa), a mixture of c. pyrenoidosa and cyanobacterial strains, and natural particles from the reser ...	2012	22678553
bacterial epibionts of daphnia: a potential route for the transfer of dissolved organic carbon in freshwater food webs.	the identification of interacting species and elucidation of their mode of interaction may be crucial to understand ecosystem-level processes. we analysed the activity and identity of bacterial epibionts in cultures of daphnia galeata and of natural daphnid populations. epibiotic bacteria incorporated considerable amounts of dissolved organic carbon (doc), as estimated via uptake of tritiated leucine: three times more tracer was consumed by microbes on a single daphnia than in 1 ml of lake water ...	2014	24694716
removal of polar uv stabilizers in biological wastewater treatments and ecotoxicological implications.	the present study describes the development, validation and application of a fully automated analytical method based on on-line solid-phase extraction-liquid chromatography-tandem mass spectrometry (on line spe-hplc-ms/ms) to assess the removal efficiency in water works and the ecotoxicological implications derived of the two most used benzotriazole-class uv stabilizers (bzts), namely 1h-benzotriazole (bzt) and 5-methyl-1h-benzotriazole (mebzt). influent and effluent wastewater samples from 20 w ...	2015	24746525
genetic structure of daphnia galeata populations in eastern china.	this study presents the first examination of the genetic structure of daphnia longispina complex populations in eastern china. only one species, d. galeata, was present across the eight investigated lakes; as identified by taxon assignment using allelic variation at 15 microsatellite loci. three genetically differentiated d. galeata subgroups emerged independent of the type of statistical analysis applied. thus, bayesian clustering, discriminant analysis based on results from factorial correspon ...	2015	25768727
assessing toxicity of copper nanoparticles across five cladoceran species.	as a result of ever increasing applications, nanoparticles will eventually end up in the environment. however, currently no common principle has been established to help understand the toxicity of nanoparticles (nps) across species. therefore, it is difficult to estimate the potential risks of nanoparticles to untested species in the environment. the authors exposed 4 different sizes of copper nanoparticles (cunps) and 1 submicron-sized copper particle to 5 cladoceran species (daphnia magna, dap ...	2015	25826796
the filtration apparatus of cladocera: filter mesh-sizes and their implications on food selectivity.	the filtering apparatus of eleven cladoceran species was studied. the distances between the setulae, which act as filters, were measured. among adult individuals, they vary from 0.2 μm in diaphanosoma brachyurum to 4.7 μm in sida crystallina. species can be grouped according to the mesh-sizes, as "fine mesh filter-feeders": diaphanosoma brachyurum, ceriodaphnia quadrangula, chydorus sphaericus, daphnia cucullata and daphnia magna; "medium mesh filter-feeders": daphnia galeata, d. hyalina. d. pul ...	1981	28309989
facing multiple enemies: parasitised hosts respond to predator kairomones.	during their lifetime most organisms are exposed to various enemies influencing their victims in multiple direct and indirect ways. most studies concentrate on the effects of one enemy at a time, thereby not taking into account that in nature organisms are often simultaneously exposed to more than one enemy. we conducted a life-history experiment to investigate the simultaneous effects of predators (fish, leuciscus idus) and parasites (microparasite, caullerya mesnili) on their victim (daphnia g ...	2002	28547411