Freshwater Rotifer Brachionus Calyciflorus Research Articles

First Feeding in the African Catfish Clarias anguillaris Fry in Tanks with the Freshwater Rotifer Brachionus calyciflorus Cultured in a Continuous Feed Back Mechanism in Comparison with a Mixed Zooplankton Diet

First Feeding in the African Catfish Clarias anguillaris Fry in Tanks with the Freshwater Rotifer Brachionus calyciflorus Cultured in a Continuous Feed Back Mechanism in Comparison with a Mixed Zooplankton Diet

Cross-phylum comparison of a chronic biotic ligand model to predict chronic toxicity of copper to a freshwater rotifer, Brachionus calyciflorus (Pallas)

Short chronic 48-h toxicity tests with the freshwater rotifer Brachionus calyciflorus (Pallas) were conducted to assess the modifying effects of pH and natural dissolved organic carbon (DOC) concentration on reproductive toxicity of Cu. Toxicity tests were carried out in four test waters according to a 2×2 design, in which pH (6 and 7.8) and DOC (5 and 15 mg C/L) were the test variables. Concentrations of dissolved Cu with no observed effect at 48 h (NOEC) varied 12-fold between 8.2 and 103 μg/L. Higher DOC and higher pH resulted in a reduction of toxicity, which is in line with the concepts of the biotic ligand model (BLM). A chronic Cu-BLM, originally developed for the cladoceran Daphnia magna, was calibrated to the rotifer dataset and was found to be able to predict all rotifer NOECs with an error factor of less than 1.6. This finding may be of great interest for risk assessment and the establishment of water quality criteria, as it suggests that chronic Cu-BLMs are comparable across phyla (i.e., arthropoda to rotifera).

Life History Traits of Mictic Females in Two Strains of Brachionus calyciflorus (Rotifera)

ABSTRACT We compared the life history traits of unfertilized mictic females (UMF) and fertilized mictic females (FMF) in two strains of the freshwater rotifer Brachionus calyciflorus obtained from Qingdao and Wuhu cities of China and cultured them at three different algal concentrations (2.0, 5.0 and 8.0x16cells/ml). Food concentration significantly affected the duration of the post-reproductive period and the egg volume of UMF as well as the duration of the pre-reproductive period, the egg volume, and the reproductive investment of FMF of the Qingdao strain. Food also influenced the pre-reproductive period, the mean life span, the egg volume, and the reproductive investment of UMF and FMF of the Wuhu strain. At the various food concentrations, there were also significant differences in many of the life history characteristics between the two strains of rotifers.

은어 자어 (Plecoglossus altivelis) 사육에 있어서 담수산 rotifer (Brachionus calyciflorus)의 먹이효과

This study investigated the possibility of salinity acclimation of freshwater rotifers (Brachionus calyciflorus) as live food for sweetfish (Plecoglossus altivelis) larvae, and also examined the optimal salinity for the growth of sweetfish. Freshwater rotifers cultured in 0 and 4 PSU and seawater rotifers (B. rotundiformis) cultured in 33 PSU were supplied to the larvae with four kinds of enrichment material (condensed freshwater Chlorella, <TEX>$\omega-yeast,$</TEX> baker's yeast, Super Selco) and larval growth at 4 PSU was examined. Growth of the freshwater rotifers positively increased from 0 PSU to 6 PSU, but decreased when over 8 PSU was reached. Growth and survival of the sweet fish larvae reared in 0 PSU were significantly lower than those reared in either 4 PSU or 33 PSU. This indicated that the freshwater rotifers (B. calyciflorus) could be used as live food for sweetfish larvae reared in 4 PSU. The body weight of sweetfish larvae fed on freshwater rotifers enriched with Super Selco was the highest at 0.163 mg, but there was no significant difference in survival and body length of the fish fed with the other enrichment materials. The content of n-3 HUFA of the sweetfish larvae fed on the freshwater rotifers enriched with Super Selco and the condensed freshwater Chlorella was higher than that enriched with <TEX>$\omega-yeast$</TEX> and baker's yeast. These results indicated that B. calyciflorus cultured with the condensed freshwater Chlorella could be used for the sweetfish larvae without enrichment, and the most efficient enrichment material for B. calyciflorus is Super Selco.

고밀도 배양에 있어 먹이종류와 공급량 및 vitamin B12첨가에 따른 담수산 rotifer (Brachionus calyciflorus)의 성장

This study investigated the effects of food type (condensed freshwater Chlorella, dried Chlorella, dried Spirulina, dried Schizochytrium, baker's yeast and <TEX>$\omega-yeast$</TEX>) and amount, and supplementation of vitamin <TEX>$B_{12}$</TEX> on the growth of freshwater rotifer (Brachionus calyciflorus) in high density culture. Growth of rotifers fed condensed freshwater Chlorella was the highest and its density ranged <TEX>$7.65-8.14{\times}10^3\;inds./mL.$</TEX> The primary lipid acids of rotifers fed condensed freshwater Chloyella were linoleic and linolenic, and their amount (<TEX>$\%$</TEX> of total fatty acids) were <TEX>$48.8\%\;and\;26.8\%,$</TEX> respectively. This suggests that condensed freshwater Chlorella would be an effective diet for high quality and quantity rotifers, which in turn serve as live food for freshwater fish larvae. Growth rate of rotifers with Chlorella supplementation increased as amount of supplementation increased up to 1.5 and 2.5 mg at 28 and <TEX>$32^{\circ}C$</TEX>, respectively. However, undissolved ammonia toxicity and packing volume of Chlorella in culture medium, reached the optimal conditions for the stable and effective cultivation of rotifers when amount of condensed freshwater Chlorella was 1.5 mg in dry weight per 1,000 rotifers at <TEX>$28^{\circ}C\;and\;32^{\circ}C$</TEX> Growth of rotifers in condensed freshwater Chlorella with vitamin <TEX>$B_{12}$</TEX> supplementation was significantly higher than that of rotifers without supplementation. However, no significant difference was found among the different concentrations of vitamin <TEX>$B_{12}.$</TEX> Therefore, vitamin <TEX>$B_{12}$</TEX> could improve the growth of rotifers (B. calyciflorus).

Effect of thiophanate-methyl on the reproduction and survival of the freshwater rotifer Brachionus calyciflorus Pallas.

Effect of thiophanate-methyl on the reproduction and survival of the freshwater rotifer Brachionus calyciflorus Pallas.

Recent developments in the application of live feeds in the freshwater ornamental fish culture

The industrial development of freshwater ornamental fish culture has been hampered by the lack of suitable live feeds for feeding the fish at the various production stages. This paper reports the recent developments in the applications of the freshwater rotifers ( Brachionus calyciflorus), Artemia nauplii, decapsulated Artemia cysts and on-grown Artemia in the freshwater ornamental fish culture. Results demonstrate that the rotifers are an ideal starter feed for dwarf gourami ( Colisa lalia), a typical freshwater ornamental fish species with larvae that are too small to ingest Artemia nauplii or Moina at its first feeding. Compared with the conventional yolk food, the use of rotifers as a starter feed significantly improves the growth and survival of the gourami larvae (Days 2–12), and the beneficial effects are extended to the subsequent Artemia-feeding phase (Days 13–32). The freshwater rotifers and Artemia nauplii are also useful in raising Discus larvae in the absence of their parents, which would eliminate the risk of larvae being eaten by the parent fish. Work on decapsulated Artemia cysts indicates that the cysts could be used as a substitute for Artemia nauplii or Moina in freshwater ornamental fish culture. The fry of all the five common ornamental fish species tested (guppy Poecilia reticulata, molly Poecilia sphenops, platy Xiphophorus maculatus, swordtail Xiphophorus helleri and neon tetra Hyphessobrycon herbertaxelrodi) could readily feed on the decapsulated cysts, and their performances in terms of stress resistance, growth and survival are comparable to or better than those fed on Artemia nauplii or Moina. A culture system for production of on-grown Artemia has also been developed specifically for the use in freshwater ornamental fish farms. The system, using diluted artificial seawater of 20‰ for culture, has a mean production rate of 3 kg/m 3 of water in a 12-day cycle and a production capacity of 8 metric tons of on-grown Artemia a year. With the system, farmers could produce any specific size of on-grown Artemia of up to 5 mm to suit the age and size of their fish, by varying the time of harvesting. This characteristic, coupled with the use of bioencapsulation technique to enhance the quality of the on-grown Artemia, would make the organism an ideal nursery diet for freshwater ornamental fish. All these results show that the live feeds used in marine foodfish hatchery could be applied to freshwater ornamental fish culture to improve their performance.

Toxicity identification evaluation of leachates from municipal solid waste landfills: a multispecies approach

The toxicity of leachates from two municipal solid waste (MSW) landfills in Southern Italy was characterized using a toxicity identification evaluation procedure. The chemical and physical fractionation techniques were: pH adjustment, pH adjustment/filtration, pH adjustment/C18 solid phase extraction, graduated pH and EDTA chelation. All the samples exhibited acute toxicity towards the bacterium Vibrio fischeri, the freshwater rotifer Brachionus calyciflorus and the freshwater crustaceans Thamnocephalus platyurus and Daphnia magna. Statistical techniques were used to determine the discriminatory power and the toxicity detection capacity of the different assays and to choose a minimal battery of tests for the toxicity identification of leachates. Toxicity was closely associated with pH, generally increasing at higher pH levels and decliming at lower ones. Furthermore, results showed that toxicants could be characterized as cations, basic chemicals, suspended solids and apolar compounds.

Larval rearing of burbot (Lota lota L.) using Brachionus calyciflorus rotifer as starter food

Burbot Lota lota L. is one of the endangered freshwater fish species in western Europe for which the development of controlled larval rearing procedures could produce enough material for stock enhancement. The suitability of the freshwater rotifer Brachionus calyciflorus as a start food for larviculture of burbot was investigated. After yolk-absorption, the larvae were stocked in 40-L tanks under different feeding conditions: clear water rearing conditions with rotifers (Brachionus calyciflorus) for 10 days (R), green water conditions (Chlorella sp.) with rotifers offered for 10 days (MALR), green water conditions (Chlorella sp.) for 3 days followed by clear water in combination with rotifer feeding for 7 days (AL3R), and clear water conditions with Artemia nauplii offered for 10 days (Art). After the 10-day feeding, all groups received Artemia nauplii up to 35 days post-hatching. Larval survival was counted at day 10 and at the end of the 35-day rearing experiment. At day 35, a significant survival difference was noted between the groups where rotifers were supplemented with algae vs only Artemia. At the end of the experiment, the highest survival rate (69.20%) was obtained with larvae receiving only algae in the first 3 days of feeding. Lowest survival rate (24.90%) was obtained with larvae receiving only Artemia for 35 days. This indicates that smaller prey are essential for burbot at first feeding. Larval length and wet weight were measured at the time of mouth opening, at days 7, 10, and 21, and at the end of the experiment (day 35). On day 35, mean length of the larvae varied significantly between the treatments. However, the final wet weight of the larvae did not vary significantly between the treatments.

Cyst-based toxicity tests. XI. Influence of the type of food on the intrinsic growth rate of the rotifer Brachionus calyciflorus in short-chronic toxicity tests.

As important members of zooplankton communities worldwide, rotifers are used extensively in ecotoxicological research. Chronic rotifer tests are, however, dependent on live algal food which adds to the complexity, the variability and the costs of these bioassays. To bypass the former problem, experiments have been undertaken with the freshwater rotifer Brachionus calyciflorus, to determine their intrinsic growth rate (r) when fed for 48 h on a mixture of green algae (Raphidocelis subcapitata recently renamed Pseudokirchneriella subcapitata) obtained from algal beads stored for different periods of time, and other inert foods. All tests have been performed in disposable multiwells, in 1 ml cups each inoculated with 1 rotifer freshly hatched from dried cysts. The majority of the growth tests was performed in eight replicates. The investigations revealed that microalgae from algal beads stored for up to one year, in darkness, at 4 degrees C, supplemented with dried blue-green algae (Spirulina) gave satisfactory rotifer reproduction. The intrinsic growth rates of the rotifers, were, however, dependent on the storage time of the algal beads; the highests r's (0.7-0.8) were obtained with algae from beads not older than four months. Growth tests with combinations of P. subcapitata and other inert feeds revealed that the enrichment food Selco used in aquaculture, also gave the same reproductive output as the combination microalgae/Spirulina. A rotifer growth experiment with 18 replicates showed that the variation coefficient is below 20% when the tests comprise eight replicates. This study demonstrated that microalgae from beads, supplemented by other inert food, open the door for a practical and cost-effective short-chronic rotifer test, which is totally independent of the culturing of both the test species and its live food.

Full life-cycle toxicity assessment using rotifer resting egg production: implications for ecological risk assessment

The majority of standardized toxicity tests incorporate only a fraction of the test organism's life-cycle. However, in natural ecosystems, organisms may be exposed at various times during their life-cycle or throughout their life-cycle. Thus, ecotoxicological data from standardized toxicity tests is of limited ecological relevance. Existing standardized toxicity tests using the freshwater rotifer Brachionus calyciflorus utilize 24-h survival or 48-h asexual reproduction as endpoints, despite evidence that sexual reproduction is more sensitive. A 96-h B. calyciflorus resting egg toxicity test was developed and used to estimate the toxicity of pentachlorophenol (PCP) and copper. Results were compared to a variety of acute and sublethal endpoints for both toxicants. The B. calyciflorus 96-h resting egg production NOEC for PCP of 10 μg/l was 20 times lower than the 48-h asexual reproduction no observed effect concentration (NOEC) and 120 times lower than the 24-h acute lethal concentration 50%. The 96-h resting egg production NOEC for copper of 2.8 μg/l was 7 times lower than the 48-h asexual reproduction NOEC and nine times lower than the 24-h acute LC50. Resting egg production was a more sensitive indicator of toxicity than several other sublethal endpoints as well. These results indicate that partial life-cycle toxicity tests are not sufficiently sensitive to detect ecologically relevant adverse effects.

Use of freshwater rotifer Brachionus calyciflorus in screening assay for potential endocrine disruptors

Abstracteports of the effectsofendocrinedisruptorsonaquatic invertebrates arebecoming increasingly common. However, little is known about the endocrine systems of most aquatic invertebrates, limiting the development of assays based on endocrine mechanisms. As a result, endocrine disruption is often inferred through the effects caused by the chemical of interest, making it difficult to rule out other mechanisms of toxicity. To be a good candidate for an endocrine disruptor, effects should be observed in processes known to be under endocrine control, at life stages where endocrine signals are known to be active, and at concentrations below acute and chronic toxic effects. We developed a 96‐h reproductive assay using the freshwater rotifer Brachionus calyciflorus to screen for potential endocrine disruptors and examined cadmium, chlorpyrifos, naphthol, pentachlorophenol, estradiol, methoprene, precocene, nonylphenol, flutamide, and testosterone for effects on asexual and sexual reproduction. Flutamide, testosterone, and nonylphenol inhibited fertilization of sexual females at concentrations of 1, 10, and 50 μg/L, respectively. The fertilization no‐observable‐effect concentrations (NOECs) for these compounds were 5 to 200 times lower than previously described reproduction NOECs for B. calyciflorus. Sexual reproduction was inhibited with no effects on asexual reproduction, increasing the likelihood that these specific reproductive effects occurred through an endocrine mechanism. Rotifer reproduction assays may be a useful, rapid, and inexpensive method for screening compounds suspected to have endocrine disrupting activity in aquatic invertebrates.

The swimming behaviour of Brachionus calyciflorus (rotifer) under toxic stress : II. Comparative sensitivity of various behavioural criteria

Changes in the swimming behaviour of the freshwater rotifer Brachionus calyciflorus, analysed using an automated tracking system, were used as sublethal indicators of toxic stress. Three swimming criteria were measured (speed, sinuosity, and the periods of swimming), and the influence of three chemicals [copper, pentachlorophenol (PCP) and γ-hexachlorocyclohexane (lindane)], on the rotifer locomotory characteristics were examined after 5 minute, 2 and 6 hour exposure periods. For each toxicant used, the 6h-EC 50 values calculated from either speed, periods of swimming or sinuosity were comparable to the 96h-, 48h- or 24h-L(E)C 50s obtained in conventional acute toxicity tests as well as EC 50s of several other rapid-screening bioassays. Additionally, different behavioural alteration patterns were observed which depended on the toxicant tested. The swimming sinuosity of the rotifer was not affected by Cu and only slightly impacted by PCP whereas sinuosity was the only criterion affected by sublethal lindane concentrations. Alterations of both speed and period of swimming induced by short exposures to copper and PCP were not observed when using lindane. Changes in the swimming patterns are discussed in the light of the general mode of action of the respective toxicants.

Comparison of the fatty acid composition of the freshwater fish larvae Tilapia zillii, the rotifer Brachionus calyciflorus, and the microalgae Scenedesmus abundans, Monoraphidium minitum and Chlorella vulgaris in the algae-rotifer-fish larvae food chains

The proximate and the fatty acid analysis of the warm freshwater fish, Tilapia zillii larvae, the freshwater rotifer Brachionus calyciflorus and the microalgae Scenedesmus abundans, Monoraphidium minitum and Chlorella vulgaris each constituting a different food chain with B. calyciflorus and T. zillii larvae have been carried out. C. vulgaris had significantly higher lipid content than the other two microalgae and this was also reflected in the lipid content of B. calyciflorus fed each of the microalgae separately. Five fatty acids dominated in all the microalgae, namely 18:3 n−3, 18:2 n−6, 18:0, 18:1 and 16:0 though there were significant differences both in quantitative distribution of these acids and the total fatty acid content. The content of 18:3 n−3, 18:2 n−6 and 16:0 and the total fatty acid content of C. vulgaris were considerably higher than the corresponding values in the other two microalgae. But interestingly, these strong differences were not reflected in B. calyciflorus samples fed these microalgae separately though the one fed C. vulgaris had slightly higher total fatty acid content than the other two rotifer samples. One can consider that the freshwater rotifer B. calyciflorus is capable of creating its own characteristic fatty acid content up to a sufficient level even when cultured with a fatty acid deficient algae probably by consuming excessive amounts of this algae compared to other algae of relatively high fatty acid content. The proximate and fatty acid analysis results of the three T. zillii larvae fed the three B. calyciflorus samples obtained by culturing with three different microalgae were very similar. This was an expected result because the three B. calyciflorus samples did not differ much from each other. The low 18:2 n−6 (1.66–3.53 mg g −1 DM) and 18:3 n−3 (1.14–1.22 mg g −1 DM) content and the relatively high 22:6 n−3 (10.72–14.38 mg g −1 DM) content of the T. zillii larvae samples indicated that they were capable of elongating and desaturating both linoleic and linolenic acids of the B. calyciflorus samples.

Feeding sequences (rotifer and dry diet), survival, growth and biochemical composition of African catfish, Clarias gariepinus Burchell (Pisces: Clariidae), larvae

The suitability of the freshwater rotifer Brachionus calyciflorus as starting food for the larviculture of African catfish, Clarias gariepinus Burchell, was investigated through studies of growth and fatty acid profiles in relation to different feeding sequences combining live food and dry diet in various proportions and during different mixed feeding periods. The best results for survival were observed when rotifers were supplied during the first week of feeding, i.e. sequences R2 (exclusive supply of rotifers, then dry diet from day 8, onwards) and R5 (50% rotifers+50% dry diet until day 7, then dry diet 100%), reaching 99.2% and 96.3%, respectively. The specific growth rate of larvae was largely dependent on the duration of preliminary feeding with the rotifers. A feeding with rotifers as a unique food source did not produce satisfactory growth during the first week of feeding. A precocious weaning showed that the highest growth rate and protein efficiency ratio (PER) can be obtained by feeding the larvae rotifers in association with a dry diet. The best PER and protein productive value (PPV) were recorded with feeding sequences R2 and R5. On the other hand, the series of polyunsaturated fatty acids was characterized by a relatively constant concentrations, and represented about 11.6% of the total fatty acids in sequence R2 because of the presence of the acids of the linoleic series, which apparently originated from the food. The R5 regime provided larvae with significant amounts of highly unsaturated fatty acids, such as linolenic acid C18:3n-3.

Toxicity Evaluations of Wastewaters in Austria with Conventional and Cost-Effective Bioassays

The acute toxicity of 42 samples of different types of domestic and industrial discharges was assessed with a battery of tests comprising the standard Daphnia magna bioassay and three cost-effective new microbiotests (cyst-based Toxkits): the Rotoxkit F with the freshwater rotifer Brachionus calyciflorus and the Streptoxkit F and Thamnotoxkit F tests with the freshwater fairy shrimps Streptocephalus proboscideus and Thamnocephalus platyurus, respectively. Chemical analyses were performed for conventional water quality parameters such as chemical oxygen demand (COD), biological oxygen demand (BOD5), NO2, NH2, NH4+, O2, and pH. Toxicity of the samples, expressed as German regulatory G-values, was found to vary between 1 and 128. The results of these toxicity tests indicate that the Toxkit bioassays were as sensitive as the D. magna acute test. The crustacean T. platyurus was in 75% of the toxic samples more sensitive than D. magna. Relationships between the chemical composition and the toxicity of the discharges could be established in some cases, but not in others, which confirms the difficulties of extrapolating toxic hazards of complex wastes from (mostly restricted) chemical analyses. This study demonstrates the potential of cost-effective bioassays (such as, e.g., cyst-based Toxkits) as attractive alternatives to (expensive) conventional bioassays for routine monitoring of effluents and wastes.

The swimming behaviour of Brachionus calyciflorus (rotifer) under toxic stress. I. The use of automated trajectometry for determining sublethal effects of chemicals

Changes in the locomotory behaviour of the freshwater rotifer Brachionus calyciflorus were used as sublethal indicators of toxic stress. To that end, the swimming behaviour of this rotifer was analysed using an automated tracking system. The swimming speed (temporal factor), the swimming sinuosity (spatial factor), and the periods of swimming were measured and the influence of four chemicals, each representing a distinct chemical class (copper, pentachlorophenol, lindane and 3,4-dichloroaniline), on the rotifer's swimming characteristics were examined. The three test parameters exhibit different sensitivities depending on the chemical tested. The 2-h EC 50s obtained with the behavioural test were of the same order of magnitude as the 24-h LC 50s resulting from conventional acute toxicity tests with the same test species. This potential use of behavioural test criteria for sublethal toxicity testing with rotifers is briefly discussed.

Ecotoxicological Studies with the Freshwater Rotifer Brachionus calyciflorus: IV. Rotifer Behavior as a Sensitive and Rapid Sublethal Test Criterion

The swimming behavior of the freshwater rotifer Brachionus calyciflorus exposed to copper (Cu), pentachlorophenol (PCP), 3,4-dichloroaniline (DCA), and lindane, for periods ranging from 5 min to 5 hr, was examined. A swimming behavior test is described which is based on the rotifers′ movement rates as they swim over a grid. For all four toxicants a clear dose-response was observed, with the swimming activity decreasing with increasing toxicant concentrations. For Cu the EC 50′s, the concentration that reduced the swimming activity to 50% of that of the control value, sharply decreased from 0.22 mg/liter after an exposure of 5 min to 0.068, 0.038, and 0.014 mg/liter after exposures of 30, 60, and 300 min, respectively. PCP affected the rotifers′ swimming behavior more gradually, with EC 50′s decreasing from 7.0 mg/liter after an exposure of 5 min to 5.9, 5.4, and 1.5 mg/liter after 30, 60, and 300 min, respectively. A similar pattern was found for DCA with EC 50′s ranging from 193 to 45.5 mg/liter for the 5-min and 3-hr exposures, respectively. Exposed to lindane however, B. calyciflorus swimming activity exhibited a different response, and the EC 50′s gradually increased from 13.7 mg/liter after an exposure of 5 min to significantly higher values of 16.4 and 18.5 mg/liter after periods of 1 and 5 hr, respectively. The results of the swimming activity assays were compared to those of acute and chronic toxicity tests performed with the same test species. The potential use and relevance of this behavioral test criterion were evaluated and discussed.

Rapid toxicity assessment using esterase biomarkers inBrachionus calyciflorus (rotifera)

We have developed biomarkers of sublethal toxicity in the freshwater rotifer Brachionus calyciflorus based on the reduction of enzyme activity. Esterase and phospholipase A2 activity was quantified in single rotifers using image analysis and a fluorescence detection system. Esterase activity was localized in the gut and phospholipase A2 activity in the corona of females. Quantitation of enzyme activity demonstrated that toxicant stress reduced activity in a dose-dependent manner. Concentration-response relationships are described for 10 compounds representing a variety of toxicant classes and NOECs are reported. Esterase and phospholipase A2 activities were generally less sensitive end points than reproduction NOECs, but usually were more sensitive than LC50s. Since in vivo enzyme activity can be assessed in 1 h, these biomarkers will be useful where rapid results are important. The cost of performing in vivo enzyme inhibition tests is substantially less than traditional whole animal tests because these require three times more person-hours to execute. Obtaining test animals by hatching cysts, their sensitivity to toxicants, and the rapid results make the rotifer esterase and phospholipase A2 tests good candidates for inclusion in a test battery for rapid toxicity assessment. © 1994 by John Wiley & Sons, Inc..

Rapid toxicity assessment using rotifer ingestion rate

Rapid toxicity assessment is an important goal in aquatic toxicology. Ecologically important processes that can be assessed more rapidly than mortality or fecundity, while maintaining sensitivity to toxicants would be especially useful endpoints. Feeding behavior of rotifers is significant ecologically because of its direct effects on reproduction, population growth, and algal species composition. Techniques were developed to quantify ingestion rate in the freshwater rotifer Brachionus calyciflorus in 1 h, using fluorescently labeled latex spheres. The number of spheres ingested in a fixed feeding interval is directly proportional to the intensity of fluorescence in the gut. Gut fluorescence was quantified in individual females using an image analysis system. The effects of several types of toxicants on ingestion rate are reported and compared to acute and chronic values from whole animal tests.