Daphnia Magna Straus Research Articles

Acute toxicity tests with Daphnia magna straus and Pimephales promelas rafinesque in support of national pollutant discharge elimination permit requirements

The purpose of this study was to determine the static acute toxicity of aniline, p-chloro- m-cresol and 2(2,4,5-trichlorophenoxy) propionic acid (silvex) to daphnids ( Daphnia magna) and bis(2-chloroethoxy)methane and 2-sec-butyl-4,6-dinitrophenol (dinoseb) to both daphnids and fathead minnows ( Pimephales promelas). These data were needed to fulfill requirements established in the NPDES Permit (National Pollutant Discharge Elimination System) issued to the Michigan Division of The Dow Chemical Co. (Midland, Mich., U.S.A.) by the State of Michigan. Where appropriate, water quality-based effluent limitations could be recommended based on the acute toxicity data generated during this study. The results of the acute toxicity tests indicated that bis(2-chloroethoxy)methane was practically non-toxic to both daphnids and fathead minnows (LC 50 values of 201 and 184 mg l −1, respectively); additionally, silvex was also found to be practically non-toxic to daphnids (LC 50 value > 140 mg l −1). Aniline was highly toxic and p-chloro- m-cresol moderately toxic to daphnids, with calculated LC 50 values of 0.17 and 2.0 mg l −1, respectively. Dinoseb was highly toxic both to daphnids and fathead minnows, with reported LC 50 values of 0.24 and 0.17 mg l −1, respectively.

Effect ofHexageniaonDaphniaresponse in sediment toxicity tests

AbstractThe toxicity of 12 freshwater sediments to the water flea,Daphnia magnaStraus, and the mayfly nymph,Hexagenia, were tested in recycling laboratory microcosms. The organisms were tested both together and singly. Significant differences inDaphniamortality between test and control sediments occurred in only two cases in whichDaphniawas tested alone, and in five cases in which it was tested withHexagenia.SignificantHexageniamortality occurred in only two cases. The results imply that (a)Hexageniais a less sensitive indicator of freshwater sediment toxicity than isDaphniaand (b) the presence ofHexageniausually intensifies theDaphniaresponse. Tests that combine these two organisms are recommended, sinceDaphnia, although an open‐water species, responds not only to dissolved materials in the water but also to particulates released from the sediments by the physical activity ofHexagenia.These types of tests could be used, on a standardized, routine basis, as indicators of potential problems.

Notes on the systematics and ecology of Daphnia pulex LEYDIG in Northern Canada

AbstractDaphnia populations from the region of Yellowknife (N. W. T.) on the Great Nave Lake, from Tuktoyaktuk (N. W. T.) on the coast of the Beaufort Sea east of the Mackenzie‐Delta, and from Shingle Point (Y. T.) west of the Mackenzie‐Delta were described. Population diagrams were given for the beginning of September 1974. The populations found at the above mentioned sites were compared with Daphnia pulex from Spitsbergen and the German island of Spiekeroog. Though some characteristics of Daphnia middendorffiana FISCHER occurred, mainly in individuals from very northern ponds, these were always found in individuals which also possessed some of the characteristics of Daphnia pulex. In every pond, specimens with characteristics of Daphnia middendorffiana lived together with other individuals resembling Daphnia pulex. Males were found in three out of the four visited ponds on the shore of the Arctic Sea, and were apparently Daphnia pulex. All the material sampled in northern Canada was regarded as belonging to Daphnia pulex LEYDIG 1860 emend. RICHARD 1896. There was evidence, that characteristics of Daphnia middendorffiana develop under the influence of environmental conditions, such as food supply. Daphnia magna STRAUS was found far north of the arctic circle.

The sensitivity of Daphnia magna straus to changes in light intensity at various adaptation levels and its implication in diurnal vertical migration

1. The threshold value of the absolute change in light intensity ΔI necessary to evoke a phototactic reaction in Daphnia magnaStraus was estimated at various adaptation intensities between 3.4×100 and 3.4×104 erg cm−2sec−1. 2. The results point at the existence of two distinct functions: for I < 40 erg cm−2 sec−1: ΔI = 0.21I0.49; I ≧ 40 erg cm−2 sec−1: ΔI= 0.03I1.06. 3. Starting at 40 erg cm–2 sec−1 the threshold of the relative change in light intensity increases for lower as well as for higher adaptation intensities. 4. Neither Weber's Law nor Hecht's exponential function (Hecht, 1934) seem to cover the results sufficiently. These are, however, highly comparable with those obtained by Heberdey and Kupka (1942) working with Daphnia pulexDe Geer. Our interpretation differs from theirs, however. We think of two different phototactic mechanisms. 5. The significance of the results for diurnal vertical migration of Zooplankton is pointed out.