We examined how alkaline phosphatase (AP) activity within the bodies and in the materials released by the crustacean Daphnia magna responds to variable algal food phosphorus (P)-content. We found that Daphnia eating P-poor food (C:P approximately 700) had significantly higher AP activity in their bodies on a mass-specific basis compared with individuals eating P-rich food (C:P approximately 100...

The systematic biology of the subgenus Daphnia s . s . remains confused. Prior attempts at resolution used chiefly postabdominal claw morphology, chromosome numbers and rRNA gene sequences as characters for higher-level relations. Still, several taxa, such as Daphnia curvirostris Eylmann, 1878, have unclear affiliations. We addressed the position of D. curvirostris in this genus by estimating p...

BACKGROUND RNA interference (RNAi) is an important molecular tool for analysis of gene function in vivo. Daphnia, a freshwater microcrustacean, is an emerging model organism for studying cellular and molecular processes involved in aging, development, and ecotoxicology especially in the context of environmental variation. However, in spite of the availability of a fully sequenced genome of Daph...

Recent behavior experiments have demonstrated that paddlefish can make use of stochastic resonance while feeding on Daphnia plankton. Here we calculate the information content of the noisy Daphnia signal at the paddlefish rostrum using an exact statistical treatment of threshold stochastic resonance as a minimal neural model. These calculations compare well with experimentally obtained data on ...

It is known that the zooplankter Daphnia induces colonies in the alga Scenedesmus. As Daphnia grazes on Scenedesmus, it has been postulated that colony formation represents an algal defense mechanism. This induction of Scenedesmus coenobia/colonies by Daphnia could be associated with a substance exuded by the animals that acts as a specific infochemical (kairomone) for Scenedesmus. However, the...

We examined phylogenetic relationships among Daphnia using mitochondrial DNA (mtDNA) sequences from the small subunit ribosomal RNA (12S), cytochrome c oxidase subunit I and nuclear DNA sequences from the first and second internal transcribed spacer representing 1612 base positions. Phylogenetic analyses using several species of the three main Daphnia subgenera, Ctenodaphnia, Hyalodaphnia and D...

Filamentous cyanobacteria are unsuitable food for Daphnia due to their poor manageability, poor nutritional value and, in some cases, toxicity. As the strength of harmful effects of cyanobacteria on filter-feeding zooplankton is temperature dependent, the global warming scenarios for eutrophic lakes in temperate zone might include an escalated suppression of Daphnia populations caused by the pr...

The faecal indicator Escherichia coli plays a central role in water quality assessment and monitoring. It is therefore essential to understand its fate under various environmental constraints such as predation by bacterivorous zooplankton. Whereas most studies have examined how protozooplankton communities (heterotrophic nanoflagellates and ciliates) affect the fate of E. coli in water, the cap...

We employ semigroup and spectral methods to analyze the linear stability of positive stationary solutions of a generalized size-structured Daphnia model. Using the regularity properties of the governing semigroup, we are able to formulate a general stability condition which permits an intuitively clear interpretation in a special case of model ingredients. Moreover, we derive a comprehensive in...

considering the crucial importance of daphnia species in aquaculture, in particular for artificially- cultured sturgeon fry, a comprehensive study on the hatching requirements of their diapausing eggs seemed to be inevitable in order to obtain the ideal hatching technique. to do so, the ephippial eggs were collected from live food ponds in the cultivation and breeding centre of gorgan and after...