Dubia Survival Research Articles

Effects of food and water quality on culturing ofCeriodaphnia dubia

AbstractThe U.S. Environmental Protection Agency (EPA) has developed a 7‐d test to evaluate effluent effects onCeriodaphnia dubiasurvival and reproduction. Several foods have been used to culture and testCeriodaphnia dubiain both laboratory waters and surface waters with variable results. This study's objective was to evaluate effects of eight diets on survival and reproduction ofCeriodaphnia dubiain hard reconstituted water (HRW); HRW was used alone or supplemented with bacteria or selenium to determine whether their addition would improve survival and reproduction. Diets consisted of yeast, trout food (TF), yeast/trout food/Cerophylc̊ (YTC),Selenastrum capricornutum, Ankistrodesmus convolutus, Chlamydomonas reinhardii, Selenastrum capricornutumplus TF, andSelenastrum capricornutumplus YTC. Screening tests in HRW with each diet (at several levels) were first used to rank diets; diets with high survival (®80% at 14 d) and reproduction (®3 young per female per reproductive day) were further evaluated in multigeneration feeding tests. Finally, diets yielding high survival and reproduction in HRW were evaluated in surface and well water to verify adequacy in waters of differing composition and quality. Yeast, trout food, YTC,Selenastrum capricornutum, Ankistrodesmus convolutus, orChlamydomonas reinhardiiused alone were unacceptable for long‐term culturing in HRW under test conditions used in this project. Success of the EPA's recommended food, YTC, was dependent on water, with worst results in HRW. The addition of selenium and bacteria to the HRW did not consistently improve either survival or reproduction ofCeriodaphnia dubiain the diet tests. Some of the diet test results were confounded by the use of batches of HRW that periodically contained some unidentified components that were toxic toCeriodaphnia dubia. BothSelenastrum capricornutumplus TF andSelenastrum capricornutumplus YTC were acceptable for culturing with high survival and reproduction.

Effort-allocation analysis of the seven-day fathead minnow (Pimephales promelas) andCeriodaphnia dubiatoxicity tests

Water quality-based limits are receiving greater emphasis in National Pollutant Discharge Elimination System permits. These permits often contain requirements for conducting acute or chronic toxicity tests of wastewater and/or ambient receiving waters. In this paper, we analyze the effort (in person-hours per test-ph/t) required to conduct the 7-d fathead minnow (Pimephales pro-melas) larval survival and growth test, the 7-d Ceriodaphnia dubia survival and reproduction test, and various tasks that are associated with these two static-renewal tests (e.g., maintaining cultures of the test animals, water chemistry analyses, quality assurance/quality control needs, sampling, and reporting). This analysis shows that all of these tasks require 53.6 ph/t. For six samples (e.g., five ambient samples plus a control, or five concentrations of an effluent plus a control), the fathead minnow test requires 6.9 ph/t and the Ceriodaphnia test requires 5.8 ph/t. The effort needed to maintain fathead minnow cultures is approximately equal to that needed to maintain C. dubia cultures (5.6 vs. 5.8 ph/t). Effort expended on other components of the testing includes 7.0 ph/t for water chemistry analyses (six samples), 5.5 ph/t for test preparation and takedown, 4.0 ph/t for QA/QC, 6.0 ph/t for report writing, and 7.0 ph/t for sampling. In addition, the analysis explores the economies of scale in conducting the two toxicity tests. Finally, the study provides guidance for those who plan to conduct these tests and for those sponsors who may need a better understanding of the basis for the costs involved.

A laboratory-scale model for evaluating effluent toxicity in activated sludge wastewater treatment plants

Laboratory-scale wastewater treatment systems were used to assess the potential contribution of a specific waste source, a detergent manufacturing plant, to wastewater treatment plant (WWTP) effluent toxicity. Laboratory-scale, continuously-fed activated sludge treatment systems (CAS units) were established and seeded with sludge from one of two activated sludge WWTPs. The CAS units were fed influent from these WWTPs supplemented with detergent manufacturing plant waste (plant waste). CAS unit effluent toxicity was measured with the 7 day Ceriodaphnia dubia survival and reproduction test and the 4 day Selenastrum capricornutum population growth test. Control (ambient WWTP influent) CAS unit and actual WWTP effluents had similar toxicity, indicating the CAS units generated effluent toxicologically similar to actual effluent for the two species tested. Untreated WWTP influent was supplemented with atypically high concentrations of plant waste in an attempt to establish a dose-response relationship between influent plant waste levels and effluent toxicity. However, there was no trend toward increasing effluent toxicity to Ceriodaphnia or algae with increasing influent plant waste concentrations. Thus, the detergent manufacturing plant waste is not contributing to the toxicity of the municipal WWTP effluent. This case study demonstrated the utility of CAS units for assessing the impact of WWTP influent sources on final effluent toxicity.

Ambient toxicity dynamics: Assessments using Ceriodaphnia dubia and fathead minnow (Pimephales promelas) larvae in short‐term tests

AbstractSeven‐day‐static‐renewal tests with fathead minnow larvae (Pimephales promelas) and Ceriodaphnia dubia were conducted monthly and results were used to assess spatiotemporal patterns in toxicity at 15 sites in five streams that receive discharges from the Oak Ridge National Laboratory (ORNL). The stream‐water samples were also analyzed for pH, conductivity, alkalinity, hardness and total residual chlorine (TRC). Relationships between the ambient toxicity test results and the chemical data were evaluated by (a) examining correlations between the two data sets across all site‐test combinations and (b) principal components analyses (PCA). These approaches proved to be more appropriate than procedures typically used to evaluate effluent toxicity (e.g., analysis of variance followed by Dunnett's test or Fisher's exact test).On average, P. promelas growth and C. dubia fecundity differed little from site to site, but survival of the two species varied greatly from test to test at some sites. Mean survival and its site‐specific C.V. were inversely related both for C. dubia and P. promelas (r = ‐0.857 and ‐0.810, respectively), and the slope of this relationship was greater for C. dubia than it was for P. promelas. Thus, (a) mortality patterns for both test species suggested that episodic events controlled overall patterns in ambient toxicity and (b) the C. dubia test appeared to be more sensitive than the P. promelas test.PCA identified two water quality factors (axis I, associated with hardness–conductivity, and axis II, strongly associated with TRC) that accounted for 60.5 and 17.6%, respectively, of the total variance in the chemical data. Multiple regression analyses of toxicity test response variables in relation to the two PCA factors showed that C. dubia survival was linked to axis II (p = 0.001) but not to axis I (p = 0.10). C. dubia fecundity was linked significantly to both (p = 0.011 and p = 0.019 for axes I and II, respectively). Neither survival nor growth of P. promelas was linked statistically to either axis. Occurrence‐frequency distributions for TRC showed that concentrations high enough to kill either species were exceeded, on average, twice monthly at sites where survival of C. dubia and P. promelas tended to be low. Thus, TRC, which enters ORNL streams primarily as drinking water used in once‐through cooling systems, was implicated as a toxicant governing the ambient toxicity test outcomes.

Comparisons of single-species, microcosm and field responses to a complex effluent

Short-term, single-species toxicity tests are used to identify, regulate and monitor the discharge of problem effluents into receiving ecosystems. The ability of single-species tests to protect entire ecosystems has been questioned, and microcosm tests have been proposed as additional tools for reducing uncertainty in environmental risk assessment. We compared responses to a complex effluent in microcosms of indigenous macroinvertebrates and protozoans with responses observed in acute tests with Daphnia magna, Ceriodaphnia dubia and Pimephales promelas and in chronic survival and reproductive tests with C. dubia. The predictive utility of these various tests was then evaluated in relation to observed effects in the receiving stream. The acute LC50s (percent effluent) from the acute tests were 63.1 for P. promelas, 18.8 to 31.3 for D. magna and 54.7 for C. dubia. Results from 7-d chronic tests indicated that C. dubia survival was significantly (p ≤ 0.05) affected at 30% effluent and that reproduction was affected at concentrations ≥3% effluent. In the protozoan microcosms, community composition was significantly (p ≤ 0.05) changed at 1.0%, while protozoan species richness was significantly reduced at 3.0% effluent. In the macroinvertebrate microcosms, mayflies were the only macroinvertebrates adversely affected by the effluent. Four mayfly taxa showed significant (p ≤ 0.05) reductions in density in the 1.0% treatment and four others were significantly reduced at 10.0%; however, some chironomids had significant increases in density at 0.1% and above. Microcosm responses corresponded well with observed effects in the field. The microcosms correctly predicted which indigenous organisms would be lost and which would be stimulated at various ambient concentrations of the effluent.

COMPARISONS OF SINGLE-SPECIES, MICROCOSM AND FIELD RESPONSES TO A COMPLEX EFFLUENT

Short-term, single-species toxicity tests are used to identify, regulate and monitor the discharge of problem effluents into receiving ecosystems. The ability of single-species tests to protect entire ecosystems has been questioned, and microcosm tests have been proposed as additional tools for reducing uncertainty in environmental risk assessment. We compared responses to a complex effluent in microcosms of indigenous macroinvertebrates and protozoans with responses observed in acute tests with Daphnia magna, Ceriodaphnia dubia and Pimephales promelas and in chronic survival and reproductive tests with C. dubia. The predictive utility of these various tests was then evaluated in relation to observed effects in the receiving stream. The acute LC50s (percent effluent) from the acute tests were 63.1 for P. promelas, 18.8 to 31.3 for D. magna and 54.7 for C. dubia. Results from 7-d chronic tests indicated that C. dubia survival was significantly (p ≤ 0.05) affected at 30% effluent and that reproduction was affected at concentrations ≥3% effluent. In the protozoan microcosms, community composition was significantly (p ≤ 0.05) changed at 1.0%, while protozoan species richness was significantly reduced at 3.0% effluent. In the macroinvertebrate microcosms, mayflies were the only macroinvertebrates adversely affected by the effluent. Four mayfly taxa showed significant (p ≤ 0.05) reductions in density in the 1.0% treatment and four others were significantly reduced at 10.0%; however, some chironomids had significant increases in density at 0.1% and above. Microcosm responses corresponded well with observed effects in the field. The microcosms correctly predicted which indigenous organisms would be lost and which would be stimulated at various ambient concentrations of the effluent.

Development and validation of site‐specific water quality criteria for copper

AbstractComparative acute toxicity values for Ceriodaphnia dubia, Scapholeberis sp. and Pimephales promelas exposed to copper were used to calculate water effect ratios (e.g., site water LC50 value/reference water LC50 value), which reflect the difference in the biological availability and/or toxicity of copper between water from the Naugatuck River, Connecticut and Lake Superior reference water. These ratios were used to modify U.S. Environmental Protection Agency (EPA) ambient aquatic life criteria for copper to site‐ and station‐specific criteria, using the indicator procedure of the U.S. EPA guidelines for deriving site‐specific water quality criteria. A water effect ratio of 1.0 was established using unpolluted upstream water, resulting in a site‐specific criterion maximum concentration (CMC) and criterion continuous concentration (CCC) of 8.7 and 6.2 μg/L copper, respectively. Mean water effect ratios of 3.9 to 7.0, reflective of reduced biological availability and/or toxicity of copper, were determined for four successive downstream stations where the water contained copper and other industrial and domestic wastes. The resulting station‐specific CMCs and CCCs ranged from 32 to 57 and 22 to 39 μg/L copper, respectively. These copper criteria were compared with effluent‐contributed ambient copper concentrations and ecological survey data from each downstream station to ascertain impact on aquatic life. It was concluded that the national and site‐specific criteria derived for copper would be protective of the river's aquatic life because a relatively healthy aquatic community existed where these criteria were exceeded slightly. Whether or not the station‐specific criteria were protective could not be determined because these criteria were not exceeded at stations with healthy communities; however, where they were exceeded, impaired aquatic communities were evident.Generally, C. dubia survival and young production data from receiving water tests and copper addition tests, conducted just prior to the acute toxicity tests, were also indicative of reduced copper biological availability and/or toxicity in the Naugatuck River at downstream stations.