The authors have declared that no competing interests exist.
Re-use of this article is permitted in accordance with the Creative Commons Deed, Attribution 2. Abstract The hatching of cladoceran ephippia from a cm long sediment core was investigated, and Ceriodaphnia quadrangula clones were isolated from different sediment layers.
Bosmina microfossil data were also analyzed, and compared with the corresponding data from a Pb dated core, which allowed us to infer the age of the sediment layers. Using changes in Bosmina microfossil morphologies, we were, furthermore, able to infer the presence of different regimes of fish predation.
Newly hatched individuals had smaller eye-size in sediment layers corresponding to high predation by young-of-the-year perch. Newly hatched individuals also generally had a marked neck-spine.
In contrast, morphological characters of C. Furthermore, the laboratory grown clones only rarely produced a neck-spine.
The results suggest phenotypic variation in response to the regime under which ephippia were produced. In plankton ecology, especially cladocerans and some copepods hatched from resting eggs have been successfully employed to study changes in life-history, behavioral, or genetic characteristics in response to varying selective forces Brendonck and Meester Cladocerans have a great advantage in experimental work, as parthenogenetic clones can be established.
Most of the cladoceran studies have been carried out using Daphnia, which is abundant in many temperate lakes and also well-represented in ecological and evolutionary work in general.
Daphnia has, for instance, been used to show adaptation in resistance to pollution Kerfoot et al. Daphnia has also been used to understand fitness consequences of hatching and reproduction success Brede et al.
Typically, cladoceran ephippia have been reported to survive for a few decades Brendonck and Meesterwhich is substantially less than for certain species of copepods Hairston et al. While many cladoceran taxa other than Daphnia are also known to have egg banks Moritz ; Brendonck and Meesterthese have been much less explored.
The information provided from these studies has been extremely valuable, and the methods have been appropriate for the hypotheses tested. Nevertheless, it has also been shown Michels et al. This requires, however, methods to reconstruct changes in evolutionary pressures, an egg-bank that is rich enough for extraction of eggs with a reasonable effort, and an appropriate resolution in the sediment in relation to egg viability and the environmental variable studied.
If the above requirements are met, cladoceran ephippia could provide an excellent model to study not only major differences in characteristics produced under different regimes, but also rates at which differences are manifested in the highly variable environments cladocerans often experience.
Moreover, the cladoceran egg-bank can serve as a source to study not only the fixed genotypic manifestations, but also the phenotypic variation in the wild-type populations that are produced under changing environmental conditions.
Although the production of new genotypes in evolutionary processes remains unchallenged in ultimately causing diversification in organisms, the role of phenotypic plasticity should not be ignored in studying the response to environmental change. As phenotypic plasticity may provide an alternative to the selection for genotypes with fixed properties, and as phenotypic plasticity may in fact be an adaptive trait in itself Price et al.
For instance, Michels et al. In addition to these motives to consider phenotypic plasticity, it is also important to note that the role of phenotypic plasticity in channeling genetic diversification has received considerable attention in the recent literature Snell-Rood et al.
The mechanisms reviewed and defined in Crispo include changes in mean trait values within plastic responses the Baldwin effect; plasticity influences the survival of an individual in a new environment, dictating the course of further evolutionor driving new, genetically fixed traits through actions on developmental systems involved in producing different phenotypes genetic assimilation.
In this study, we investigate the viability of ephippia from Ceriodaphnia quadrangula in the sediment of a boreal-forest lake.
Furthermore, we explore the occurrence of neck-spines; antipredatory characteristics known to vary geno- and phenotypically in cladocerans Lass and Spaak We explore these characteristics in newly hatched individuals, which reflect phenotypic differences in the ephippia produced under different conditions.
By also using individuals reared in the laboratory over several generations, we furthermore explore variation at the genotype level under different historic conditions with regard to the above traits.
It is important to note that to date our understanding of planktivory in the study lake is restricted to fish, as invertebrate predators dominated by Bytotrephes have not been monitored.
Chronic toxicity in Ceriodaphnia dubia induced by graphene oxide. In this context, we evaluated graphene oxide (GO) effects on the freshwater cladoceran Ceriodaphnia dubia through acute and chronic toxicity, feeding rates, and reactive oxygen species This study provides useful information on GO concentrations that might impair the. ABSTRACT This study investigated the taxonomy of three groups of the cladoceran genus Ceriodaphnia in cultures being used by the U.S. Environmental Protection Agency. One taxonomic group, having heavy, triangular denticles in a pecten on the postabdominal claw and very short male antennules, was identified as £. ABSTRACT This study investigated the taxonomy of three groups of the cladoceran genus Ceriodaphnia in cultures being used by the U.S. Environmental Protection Agency. One taxonomic group, having heavy, triangular denticles in a pecten on the postabdominal claw and very short male antennules, was identified as £.
This sets limitations especially on the interpretation of neck-spines, which occur as defense against invertebrate predation reviewed by Lass and Spaak In pilot studies preceding this experiment it was, however, noted that there was marked variation on the size and occurrence of neck-spines, and we decided to include this variable to study its plasticity versus genotype level manifestations.
Hence, our interpretations on neck-spine production are limited to this aim, whereas the selective forces operating on the individuals present in the egg-bank remain to be investigated. We tentatively infer the age and fish-predation regime of each sediment layer from a previously established calibration curve based on paleolimnological data on Bosmina morphology.
Sincethe study lake has been intensively monitored, and hence for the more contemporary sediment layers, we back up the findings in the Bosmina record with known changes in planktivory Persson et al.
For historic changes, however, the inference remains more hypothetic, as it relies on the changes in Bosmina morphology, anecdotal information on fish introductions, and observations from neighboring lakes namely dominance by ninespined stickleback in lakes with no fish introductions.In the present study, the kinetics of the interaction of Cu(II) with humic acid (HA) and its influence on the toxicity of copper to Ceriodaphnia dubia were investigated by both chemical kinetic studies using a copper ion selective electrode and bioassay tests using a continuous flow‐through bioassay system.
This study was undertaken to (a) determine wastewater treatment effectiveness using two freshwater organisms, (b) compare acute toxicity results from the two species exposed to the wastewaters, and (c) link acute and potential developmental toxicity of wastewaters in one organism.
Ceriodaphnia dubia exhibited a 7 day no observable effect concentration (NOEC) of 1 mg l − 1 and S. capricornutum exhibited a 96 h NOEC of 29 mg l − 1 to an insoluble, anionic styrene–acrylic dispersion polymer with a molecular weight of 50–60 kDa used in floor finishes.
The C. dubia value was caused primarily by physical effects. Daphnia is a large genus – comprising over species – belonging to the cladoceran family Daphniidae. It is subdivided into several subgenera (Daphnia, Australodaphnia, Ctenodaphnia), but the division has been controversial and is still in barnweddingvt.com subgenus has been further divided into a number of species barnweddingvt.com understanding of species boundaries has been hindered by.
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