Daphnia


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Related to Daphnia: Daphnia pulex

Daphnia

 

a genus of freshwater animals of the suborder Cladocera. Daphnia measure 1–3 mm and have a transparent, oval, chitinous shell, whose valves are united on the dorsal side and open in the form of slits on the ventral side. Daphnia are dioecious. Some summer generations are represented only by females, which reproduce parthenogenetically. In the fall, males also appear; fertilization occurs, the females deposit one or two fertilized eggs, which are covered with a thick membrane. These eggs hibernate; in the spring females develop from them. There are a total of 26 species, 14 in the USSR; they are distributed everywhere, except in polar regions. Daphnia live in lakes, ponds, temporary bodies of water, and the backwaters of slow-moving rivers. They feed on bacteria, unicellular algae, protozoans, and the smallest particles of plant detritus. Daphnia serve as food for recently hatched and young fish (they are raised for this purpose in fisheries). Daphnia are intermediate hosts of some worms that in their adult form parasitize various vertebrates, including domestic ducks.

References in periodicals archive ?
Romare and Bergman (1999) reported that average densities of 0.3 ind [m.sup.-3] of the YOY fish can affect the recovery of Daphnia, and the latter will be totally suppressed at YOY fish densities of 0.7 ind [m.sup.-3].
A comparison of the response of Simocephalus mixtus (Cladocera) and Daphnia magna to contaminated freshwater sediments.
The canonical correspondence analysis including only the six best fitting phytoplankton species, showed that only Daphnia was most related with C.
The scope of the research included conducting of the following single-species bioassays with representatives of different trophic levels on wastewater containing phenol: algal growth inhibition test with Desmodesmus quadricauda, immobilization toxicity test with crustacean Daphnia magna Straus, fish Lebistes reticulatus Peters and Danio rerio, enzymatic tests with Daphnia magna Straus and bacteria Vibrio fischeri.
Daphnia magna (1 day young) used in the experiment was cultured according to the standard rearing procedure [25].
The present study confirmed that diazinon poses significant risk to aquatic organisms, namely, nontarget Daphnia species.
El resultado del analisis para la prueba con Daphnia magna por el modelo Probit para mortandad, se estima valores letales de 1.28 g BaS[O.sub.4]/l a las 48 horas.
However, given the sensitivity of these organisms, many other factors possibly led to this result, such as concentration of toxic substances to Daphnia, including chlorpyrifos degradation products, organic acids and even pathogenic microorganisms.
That research produced five populations of Daphnia adapted to salt concentrations ranging from the current concentration of 15 milligrams per liter of chloride in Lake George, to concentrations of 1,000 milligrams per liter as found in highly contaminated lakes in North America.
In this work it was studied the microscopic structure of the filter apparatus of three different sized species of cladoceran daphnids typical of tropical and subtropical environments (Ceriodaphnia silvestrii Daday, 1902; Ceriodaphnia cornuta Sars, 1885 and Daphnia gessneri Herbst, 1967).
Os efeitos agudos foram avaliados de acordo com a norma NBR 12713 de ecotoxicologia aquatica com o organismo Daphnia magna, sendo estimados pelo fator de toxicidade (FT) (ABNT, 2009).
Dicranophorus epicharis (32.14%), Keratella quadrata (16.96%), and Anuraeopsis fissa (9.77%) from Rotifera and Chydorus sphaericus (7.25%) and Daphnia longispina (1.20%) from Cladocera were the dominant species, while the only species of Copepoda was represented by Arctodiaptomus acutilobatus.