Effect of the epizoic rotifer Brachionus rubens on the population growth of three cladoceran species

Tropical waterbodies contain several species of toxic cyanobacteria including Microcystis, which adversely affect the somatic growth, survival and fecundity of zooplankton. Scenedesmus, one of the most common green algae, is even found in Microcystis -dominated waterbodies. It is, therefore possible that in natural ponds, rotifers and cladocerans feed on mixed phytoplankton species containing algae and cyanobacteria. In this work, we quantified demographic responses of three rotifer species (Brachionus calyciflorus, B. rubens, and Plationus patulus), and three cladoceran species (Simocephalus mixtus, Daphnia cf. mendotae and Moina macrocopa) fed toxic Microcystis aeruginosa only or mixed with Scenedesmus acutus. The highest population growth for both rotifer and cladoceran species was observed when Scenedesmus was offered alone or at 75 % of the diet. Daphnia cf. mendotae and B. rubens were less affected by Microcystis while M. macrocopa and B. calyciflorus were more adversely influenced, which was also corroborated by life table demography. In competition bioassays, D. cf. mendotae was more efficient, alone or in competition, when fed with 50 or 25 % of Microcystis. This work explains the dynamics of the zooplanktonic community against gradual changes in phytoplankton due to the presence of cyanobacteria.

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Allelopathic interactions between the macrophyte Egeria densa and plankton (alga, Scenedesmus acutus and cladocerans, Simocephalus spp.): a laboratory study

Journal of Limnology ◽

10.4081/jlimnol.2016.1397 ◽

2016 ◽

Vol 75 (s1) ◽

Cited By ~ 4

Author(s):

Cristian A. Espinosa-Rodríguez ◽

Ligia Rivera-De la Parra ◽

Aurora Martínez-Téllez ◽

Gisela C. Gómez-Cabral ◽

S.S.S. Sarma ◽

...

Keyword(s):

Population Growth ◽

Conditioned Medium ◽

Indirect Effects ◽

Population Increase ◽

Life History Strategies ◽

Direct And Indirect Effects ◽

Egeria Densa ◽

Scenedesmus Acutus ◽

Cladoceran Species ◽

Allelopathic Interactions

Allelopathic interactions between macrophytes and zooplankton are important to understand the plankton dynamics in shallow waterbodies. Egeria densa is a native, perennial, submerged macrophyte in the tropical and subtropical zones of South America. It has been introduced to Central and North America and is now common in many Mexican lakes. This macrophyte produces chemical substances that negatively affect some phytoplankton species. However, it is not clear how zooplankton species adapt different life history strategies in the chemical presence of this macrophyte. Here, we tested the direct and indirect effects of allelochemicals released by E. densa on the population growth of Scenedesmus acutus and on the demographic variables of three species of Simocephalus, S. exspinosus, S. serrulatus and S. mixtus (via alga exposed to the macrophyte allelochemicals). To quantify the effect of E. densa on S. acutus we set up four treatments: control, artificial Egeria, natural Egeria and allelochemicals from Egeria. To test the allelochemical effects on Simocephalus species, we compared four treatments: Control, indirect effect (using S. acutus grown on Egeria-allelochemicals), direct effect (using Egeria-conditioned medium) and together with both these kinds of direct and indirect effects. Scenedesmus had the highest cell density in the presence of allelochemicals from Egeria, followed by controls. The specific algal growth rate (µ) between control and allelochemicals treatment was not significant (P<0.05). However, the µ of alga in the presence of artificial or natural Egeria was significantly lower than controls or in treatment involving allelochemicals. The age-specific survivorship of the three cladoceran species was longer in treatments containing Egeria-conditioned medium. Cladocerans receiving Egeria conditioned-medium and algae cultured on macrophyte-allelochemicals also had a longer survivorship. Daily fecundity of S. serrulatus increased after reaching mid-age while S. expinosus and S. mixtus showed continuous reproduction starting from the first week. In general, Egeria-allelochemicals enhanced the age-specific reproductive output for all the three cladoceran species. The average lifespan of the three Simocephalus varied from 17 to 46 days, depending on the cladoceran species and treatment. S. serrulatus had lower lifespan compared to other two cladoceran species. For the three species, lifespan significantly increased in treatments containing macrophyte-conditioned medium + algae grown on the plant-allelochemicals; also under these conditions, both gross and net reproductive rates were significantly enhanced. This stimulatory effect was also evident in generation time (about 50% higher). The rate of population increase ranged from 0.23 to 0.38 per day for the three tested Simocephalus species but there were no significant differences (P˃0.05) among treatments. Our results suggest that the biological activity as well as physical structure of E. densa had negative effects on S. acutus population growth but had stimulatory effects on the demography of Simocephalus.

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The inhibition by ammonia of population growth of the rotifer, Brachionus rubens, in continuous culture

Aquaculture ◽

10.1016/0044-8486(85)90207-8 ◽

1985 ◽

Vol 46 (3) ◽

pp. 215-220 ◽

Cited By ~ 28

Author(s):

M. Schlüter ◽

J. Groeneweg

Keyword(s):

Population Growth ◽

Continuous Culture ◽

Brachionus Rubens

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A Tale of Two Metrics: The EPA Risk Quotient Approach versus the Delay in Population Growth Index for Determination of Pesticide Risk to Aquatic Species

10.21203/rs.3.rs-481150/v1 ◽

2021 ◽

Author(s):

John D. Stark ◽

John E. Banks

Keyword(s):

Population Growth ◽

Daphnia Pulex ◽

Growth Index ◽

Ceriodaphnia Dubia ◽

Aquatic Species ◽

Risk Quotient ◽

Cladoceran Species ◽

Generation Times ◽

Species Being

Abstract The risk that two closely related insecticides, spinetoram and spinosad, posed to three Cladoceran species, Ceriodaphnia dubia, Daphnia pulex, and D. magna was determined using two approaches, the USEPA Risk Quotient method and the Delay in Population Growth Index (DPGI). Results of the RQ method showed that spinetoram posed a risk to all three species, but spinosad posed a risk only to C. dubia. The DPGI analysis showed that exposure to spinetoram resulted in populations of all three species being delayed > 3 generation times. Exposure to the LC50 and the lower 95% CL resulted in delayed populations while exposure to the upper 95% CL concentration of spinetoram resulted in no recovery of any of the three species over the course of the modeling exercise (88 d). Exposure to the lower and upper 95% Cl and the LC50 of spinosad resulted in C. dubia populations being delayed > 3 generations. D. pulex populations were not negatively affected after exposure to spinosad. D. magna populations were delayed > 3 generations, but only after exposure to the upper 95% Cl of spinosad. These results illustrate that although the EPA risk quotient method indicated that spinetoram posed a risk to all three species and that spinosad only posed a risk to C. dubia, the DPGI showed that D. magna would be negatively affected by spinosad and none of the three species would recover after exposure to the upper 95% CL of spinetoram. Because the DPGI uses the 95% Cl as well as the LC50 in its calculation and produces a measure of population growth and recovery or lack thereof, it provides more detailed information in terms of the potential risk of pesticides to populations than the RQ method.

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