Differential filtration efficiencies of Daphnia pulex

1982 ◽  
Vol 60 (9) ◽  
pp. 2129-2133 ◽  
Author(s):  
Richard A. Osgood
Keyword(s):  
Algal Species ◽  
Daphnia Pulex ◽  
Chlorella Pyrenoidosa ◽  
Radioactive Label ◽  
Ankistrodesmus Falcatus ◽  
Filtration System ◽  
Food Concentrations ◽  
Feeding Trials ◽  
Filtering Rates ◽  
Differential Filtration

When three green algae Chlorella pyrenoidosa, Ankistrodesmus falcatus, and Closterium acerosum (Chlorophyta) were presented to Daphnia pulex in a mixture, these cells were ingested differentially; filtering rates were 1.30, 2.79, and 7.53 mL∙animal−1 h−1, respectively. Filtration rates on each of these algal species presented singly at equivalent (biovolume) food concentrations were not significantly different (p > 0.05) from the rates measured in a mixture. The algal cells for the feeding trials were individually labeled with metal tracers (Fe, Mn, and Zn) and this technique is compared with a radioactive label (32P). The differential filtration efficiencies are viewed as a passive selection mechanism resulting in preferential ingestion of larger food cells and is simply related to the physical properties of Daphnia's filtration system.

Increased fecundity of the cladoceran Moinodaphnia macleayi on a diet supplemented with a green alga, and its use in uranium toxicity tests

1993 ◽  
Vol 44 (3) ◽  
pp. 389 ◽  
Author(s):  
RV Hyne ◽  
A Padovan ◽  
DL Parry ◽  
SM Renaud
Keyword(s):  
Unsaturated Fatty Acids ◽  
Lipid Fraction ◽  
Algal Species ◽  
Cichlid Fish ◽  
Dry Weight ◽  
Scenedesmus Quadricauda ◽  
Toxicity Tests ◽  
Ankistrodesmus Falcatus ◽  
Algal Diets ◽  
Chlamydomonas Sp

The effects of two synthetic diets and four algal diets on the survival and fecundity of Moinodaphnia macleayi for use in life-cycle toxicity tests were determined. The synthetic foods were a suspension of blended cichlid fish pellets with powdered alfalfa, either prepared fresh or fermented in natural water for 3 days. The algae, isolated from the habitat of M. rnacleayi in the Alligator Rivers Region, were Selenastrum sp., Ankistrodesmus (falcatus?), Scenedesmus quadricauda and a Chlamydomonas sp. Each alga was tested alone or as a supplement to the fermented synthetic food. The diet that supported the greatest number of young and the highest survival rate over a 5-day period was a combination of the fermented synthetic food and Chlamydomonas sp. Analysis of the fatty acid composition of the lipid fraction of the four algal species showed that Chlamydomonas sp., Selenastrum sp. and Scenedesmus quadricauda had significant concentrations of the highly unsaturated fatty acids 18 : 2(n-6), 18 : 3(n-6) and 18: 3(n-3). In terms of size and dry weight, Chlamydomonas sp. was the smallest of the algal cells studied. The toxicity of uranium to M. macleayi survival, determined under standard conditions, was a lowest-observed-effect concentration (LOEC) of 200 �g L-1 after 48 h and 25 �g L-1 after 5 days.

scholarly journals Inducible morphological defense in Daphnia pulex: food quantity effects revised

2020 ◽  
Author(s):  
Sandra Klintworth ◽  
Eric von Elert
Keyword(s):  
Chemical Cues ◽  
Daphnia Pulex ◽  
Food Concentration ◽  
Bacterial Degradation ◽  
Inducible Defenses ◽  
Chemical Cue ◽  
High Food ◽  
Food Quantity ◽  
Morphological Defense ◽  
Food Concentrations

Abstract In aquatic systems, organisms largely rely on chemical cues to perceive information about the presence of predators or prey. Daphnia recognize the presence of the predatory larvae of Chaoborus via a chemical cue, emitted by the larvae, a so-called kairomone. Upon recognition, neckteeth, an alteration of the carapace, are induced in Daphnia that reduce predation rates of Chaoborus. Neckteeth induction was often reported to entail costs. In a previous study, food quantity affected the level of neckteeth induction, with stronger neckteeth induction at low food concentrations and weak induction at high food concentrations. However, reducing neckteeth induction at high food quantities seems to be maladaptive and not in accordance with the concept that inducible defenses are associated with costs. Here, we hypothesized that weaker neckteeth induction at high food concentrations is caused by increased bacterial degradation of the kairomone. More specifically, we assume that higher algal food concentration is associated with higher bacterial abundances, which degrade the kairomone during the experiment. We tested our hypothesis by treating food algae with antibiotics before providing them as food to Daphnia. Antibiotics reduced bacterial abundances at high and low food concentrations. Reduced bacterial abundances at high food concentrations led to the same level of neckteeth induction as at low food concentrations. A linear regression revealed a significant correlation of neckteeth induction to bacterial abundances. We therefore conclude that differences in neckteeth induction at different food concentrations are not caused by the food quantity effects but by differences in bacterial degradation of the kairomone.

scholarly journals Stoichiometric controls of mercury dilution by growth

2007 ◽  
Vol 104 (18) ◽  
pp. 7477-7482 ◽  
Author(s):  
Roxanne Karimi ◽  
Celia Y. Chen ◽  
Paul C. Pickhardt ◽  
Nicholas S. Fisher ◽  
Carol L. Folt
Keyword(s):  
Steady State ◽  
Rapid Growth ◽  
Daphnia Pulex ◽  
Somatic Growth ◽  
Aquatic Organisms ◽  
High Quality ◽  
Nutrient Quality ◽  
Ingestion Rates ◽  
Biokinetic Model ◽  
Ankistrodesmus Falcatus

Rapid growth could significantly reduce methylmercury (MeHg) concentrations in aquatic organisms by causing a greater than proportional gain in biomass relative to MeHg (somatic growth dilution). We hypothesized that rapid growth from the consumption of high-quality algae, defined by algal nutrient stoichiometry, reduces MeHg concentrations in zooplankton, a major source of MeHg for lake fish. Using a MeHg radiotracer, we measured changes in MeHg concentrations, growth and ingestion rates in juvenile Daphnia pulex fed either high (C:P = 139) or low-quality (C:P = 1317) algae (Ankistrodesmus falcatus) for 5 d. We estimated Daphnia steady-state MeHg concentrations, using a biokinetic model parameterized with experimental rates. Daphnia MeHg assimilation efficiencies (≈95%) and release rates (0.04 d−1) were unaffected by algal nutrient quality. However, Daphnia growth rate was 3.5 times greater when fed high-quality algae, resulting in pronounced somatic growth dilution. Steady-state MeHg concentrations in Daphnia that consumed high-quality algae were one-third those of Daphnia that consumed low-quality algae due to higher growth and slightly lower ingestion rates. Our findings show that rapid growth from high-quality food consumption can significantly reduce the accumulation and trophic transfer of MeHg in freshwater food webs.

Dissolved organic matter utilization and oxygen uptake in algal–bacterial microcosms

1979 ◽  
Vol 25 (11) ◽  
pp. 1315-1320 ◽  
Author(s):  
David L. Tison ◽  
A. J. Lingg
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Algal Biomass ◽  
Algal Species ◽  
Chlorella Pyrenoidosa ◽  
Individual Species ◽  
Bacterial Respiration ◽  
Bacterial Microbiota ◽  
Limiting Nutrient ◽  
Algal Photosynthesis

Under closed laboratory conditions, at non-limiting nutrient levels, the biomass of Anabaena variabilis. Anacystis nidnlans, Chlorella pyrenoidosa. and Selanastrum capricornutum increased with increasing levels of dissolved organic matter (DOM) as a result of bacterially produced carbon dioxide (CO2) and (or) cofactors. Oxygen (O2) produced as a result of algal photosynthesis was sufficient to supply the majority of O2 required by the bacterial community. The percentage of DOM utilized by bacteria which was subsequently incorporated into algal biomass varied with individual species indicating that the association between individual algal species and the bacterial microbiota varied.Under natural conditions bacteria could provide CO2 and (or) cofactors for algal photosynthesis which in turn supplies O2 for bacterial respiration. This mutualistic association in aquatic environments could result in an increase in planktonic and epiphytic algal biomass if other nutrients are available.

Energy Reserve Lipids of Zooplanktonic Crustaceans from an Oligotrophic Saline Lake In Relation to Food Resources and Temperature

1993 ◽  
Vol 50 (11) ◽  
pp. 2404-2420 ◽  
Author(s):  
Michael T. Arts ◽  
Richard D. Robarts ◽  
Marlene S. Evans
Keyword(s):  
Lipid Content ◽  
Saline Lake ◽  
Time Lag ◽  
Algal Species ◽  
Daphnia Pulex ◽  
Energy Reserve ◽  
Wild Populations ◽  
Or Groups ◽  
Salinity Levels ◽  
Reserve Lipid

In three zooplankton species examined over a 2-yr period in an oligotrophic saline (22 g∙L−1) lake, triacylglycerols (energy reserve lipids) were the most abundant lipid class followed by phospholipids and sterols. Marked seasonal differences in patterns of total and energy reserve lipid content in the herbivorous calanoid Leptodiaptomus sicilis were correlated with temporal patterns in edible algal biomass and temperature. The appearance of particular algal species, or groups of similar-sized species, occurred synchronously with changes in lipid content of both L. sicilis and Daphnia pulex. These periods of changing lipid content were used to infer nutritional suitability or inadequacy (unavailability) of specific algae for wild populations of zooplankton. Energy transfer from phytoplankton to the carnivorous calanoid Hesperodiaptomus nevadensis through L. sicilis involved a time lag of approximately 1–2 mo; this was hypothesized to result from a feeding dependency on L. sicilis copepodites due to a gape limitation of the predator. Demographics of D. pulex in this lake were unusual because the species was consistently absent during spring. In addition, total lipids and triacylglycerols were low (<15% and <4.5 μg∙animal−1, respectively), suggesting that D. pulex had been pushed into a subsistence niche by the rising salinity levels.

Inhibitory effect of Anabaena sp. on in situ filtering rate of Daphnia

1986 ◽  
Vol 64 (9) ◽  
pp. 1831-1834 ◽  
Author(s):  
Patricia Chow-Fraser ◽  
W. Gary Sprules
Keyword(s):  
Lake Water ◽  
Laboratory Experiments ◽  
Carapace Length ◽  
Daphnia Pulex ◽  
Biomass Concentration ◽  
Inhibitory Effect ◽  
Filtering Rate ◽  
Anabaena Sp ◽  
Filtering Rates

We found that in situ filtering rates of Daphnia spp. measured in a lake containing Anabaena were significantly lower than those measured in a filament-free lake. Even after accounting for the depressing effects of high nannoplankton biomass concentration, filtering rates in the lake with Anabaena were 64% lower than those from the filament-free lake. We also found that filtering rates for Daphnia pulex in laboratory experiments were lower when Anabaena was present in experimental beakers than when Chlorella was present. When Anabaena was removed from Three Mile Lake water, filtering rates compared closely with predicted rates based on nannoplankton concentration and carapace length alone. Our analysis indicates that the presence of Anabaena filaments depresses Daphnia grazing rates in general, and that the filaments themselves are ingested at a lower rate than algae such as Chlorella.

Browsing and grazing by cladoceran filter feeders

1979 ◽  
Vol 57 (1) ◽  
pp. 206-212 ◽  
Author(s):  
P. A. Horton ◽  
M. Rowan ◽  
K. E. Webster ◽  
R. H. Peters
Keyword(s):  
Ingestion Rate ◽  
Daphnia Pulex ◽  
Food Concentration ◽  
Suspension Feeding ◽  
Culture Vessel ◽  
Planktonic Food ◽  
Laboratory Cultures ◽  
Food Concentrations ◽  
Ceriodaphnia Quadrangula ◽  
Minimum Requirements

If different Cladocera have similar minimum requirements for suspended food, the capacity to utilize sedimented material would shift the competitive advantage to facultative bottom foragers in ponds, shallow lakes, and laboratory cultures with fluctuating levels of planktonic food. In laboratory cultures, Daphnia pulex browses or forages on the bottom of its culture vessel when suspended food concentration is too low to support reproduction or high rates or ingestion. Suspension feeding or grazing is the primary feeding mechanism only above the incipient limiting food concentration when ingestion rate is maximal, although a proportion of the animal's time is spent swimming (and therefore suspension feeding) at all food concentrations. Limited evidence suggests that different species of Cladocera have similar food levels at which reproduction is zero, yet not all are facultative browsers. Daphnia magna exhibits a similar behaviour to D. pulex but D. galeata and Ceriodaphnia quadrangula do not. These results show that the switch from grazing to browsing may be a determinant of competitive success among Cladocera.

Type III functional response in the zebra mussel,Dreissena polymorpha

2015 ◽  
Vol 72 (8) ◽  
pp. 1202-1207 ◽  
Author(s):  
Orlando Sarnelle ◽  
Jeffrey D. White ◽  
Theresa E. Geelhoed ◽  
Carrie L. Kozel
Keyword(s):  
Functional Response ◽  
Dreissena Polymorpha ◽  
Somatic Growth ◽  
Independent Set ◽  
Food Concentration ◽  
Type Iii ◽  
Feeding Experiments ◽  
Behavioral Observations ◽  
Ankistrodesmus Falcatus ◽  
Food Concentrations

Distinguishing between functional response types requires observations at low food concentrations, but surprisingly these tend to be rare. A paucity of feeding observations at low food concentrations is especially acute for dreissenid mussels, despite their importance as invading species in fresh waters. We assessed the functional response of zebra mussels (Dreissena polymorpha) via feeding experiments and behavioral observations conducted at low food levels. Critically, food levels were chosen to be in the vicinity of minimum concentrations found in lakes with established D. polymorpha populations. Results of two feeding experiments show clear evidence of a Type III functional response for D. polymorpha feeding on Ankistrodesmus falcatus — clearance rate increased with increasing food concentration at low food levels. Mussels were always open and feeding during these experiments. An independent set of behavioral observations further showed that the fraction of mussels actively feeding (valves open, siphons extended) decreased as food concentrations decreased. We also measured somatic growth of juvenile mussels at varying levels of A. falcatus over 27 days and found that mussels were able to grow at food levels where Type III behavior was observed in the feeding experiments.

Sublethal effects of the insecticide fenitrothion on freshwater phytopiankton

1995 ◽  
Vol 73 (1) ◽  
pp. 45-53 ◽  
Author(s):  
Robert A. Kent ◽  
Pierre-Yves Caux
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Sublethal Effects ◽  
Scenedesmus Obliquus ◽  
Total Lipid Content ◽  
Chlorella Pyrenoidosa ◽  
Selenastrum Capricornutum ◽  
Total Lipids ◽  
Fatty Acid Profiles ◽  
Bioconcentration Factors ◽  
Ankistrodesmus Falcatus

The effects of the insecticide fenitrothion (O,O-dimethyl-O-(3-methyl-4-nitrophenyl)phosphorothioate) were investigated on the unicellular phytoplankton Ankistrodesmus falcatus, Chlamydomonas reinhardtii, Chlamydomonas segnis, Chlorella pyrenoidosa, Navicula sp., Scenedesmus obliquus, Selenastrum capricornutum, and Staurastrum sp. at concentrations of 0.1, 1.0, and 10 mg∙L−1. Following a 24-h exposure, total lipids, fatty acid profiles, and bioaccumulation of fenitrothion into algal cells were determined for the above species. Total lipids may play an important role in determining sensitivity of phytoplankton to fenitrothion stress over 96-h exposures. A saturation occurred in A. falcatus membranes represented by the 5.4 and 4.3% increases in palmitic (16:0) and oleic (18:1) acids, respectively, and 1.8 and 7.6% decreases in linoleic (18:2) and linolenic (18:3) acids, respectively. This resulted in a shift from a profile dominated by linolenic (18:3) acid to one dominated by the more saturated oleic (18:1) acid. Bioconcentration factors (BCF), or the ratio of the total radiocarbon associated with algae, calculated for viable Chlamydomonas reinhardtii and Chlamydomonas segnis cells were 293 and 124, respectively. BCFs for dead cells were 1261 and 1025 for the same species, respectively. These investigations showed differential insecticide bioaccumulation between species. This bioaccumulation was shown to be correlated with the total lipid content of algal cells. Key words: algae, fatty acids, fenitrothion, lipids, pesticide.

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