Toxicant exposure increases threshold food levels in freshwater rotifer populations

Cecchine, Gary; Snell, Terry W.

doi:10.1002/(sici)1522-7278(199912)14:5<523::aid-tox6>3.0.co;2-2

Cited by 23 publications

(10 citation statements)

References 29 publications

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“…For the present study, food concentration determined the vulnerability of daphnid populations to chemical stress, in accordance with the common finding of food-dependent toxicity for Daphnia [9,16,32] and other species as well [33]. This dependence was manifested by an increase in the population sensitivity at low food compared with high food concentration.…”

Section: Population Responses To Chemical Stress Exposuresupporting

confidence: 90%

Predicting the sensitivity of populations from individual exposure to chemicals: The role of ecological interactions

Gabsi

Schäffer

Preuß

2014

Enviro Toxic and Chemistry

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Population responses to chemical stress exposure are influenced by nonchemical, environmental processes such as species interactions. A realistic quantification of chemical toxicity to populations calls for the use of methodologies that integrate these multiple stress effects. The authors used an individual-based model for Daphnia magna as a virtual laboratory to determine the influence of ecological interactions on population sensitivity to chemicals with different modes of action on individuals. In the model, hypothetical chemical toxicity targeted different vital individual-level processes: reproduction, survival, feeding rate, or somatic growth rate. As for species interactions, predatory and competition effects on daphnid populations were implemented following a worst-case approach. The population abundance was simulated at different food levels and exposure scenarios, assuming exposure to chemical stress solely or in combination with either competition or predation. The chemical always targeted one vital endpoint. Equal toxicity-inhibition levels differently affected the population abundance with and without species interactions. In addition, population responses to chemicals were highly sensitive to the environmental stressor (predator or competitor) and to the food level. Results show that population resilience cannot be attributed to chemical stress only. Accounting for the relevant ecological interactions would reduce uncertainties when extrapolating effects of chemicals from individuals to the population level. Validated population models should be used for a more realistic risk assessment of chemicals.

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Section: Population Responses To Chemical Stress Exposuresupporting

confidence: 90%

Predicting the sensitivity of populations from individual exposure to chemicals: The role of ecological interactions

Gabsi

Schäffer

Preuß

2014

Enviro Toxic and Chemistry

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“…As cyclically parthenogenetic zooplankters evolve rapidly (Fussmann 2011;Declerck et al 2015), it is plausible to conjecture adaptation of diapause stage production patterns under high heavy metal fluctuations. High heavy metal concentrations are known to affect the rotifer community (Cecchine and Snell 1999;Weisse et al 2013). Additionally, the diapause pattern observed in different organisms as response to arsenic might be a general response to stressors (Aruda et al 2011).…”

Section: Discussionmentioning

confidence: 93%

Diapause as escape strategy to exposure to toxicants: response of Brachionus calyciforus to arsenic

Aránguiz-Acuña

Serra

2016

Ecotoxicology

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Invertebrate organisms commonly respond to environmental fluctuation by entering diapause. Production of diapause in monogonont rotifers involves a previous switch from asexual to partial sexual reproduction. Although zooplankton have been used in ecotoxicological assays, often their true vulnerability to toxicants is underestimated by not incorporating the sexual phase. We experimentally analyzed traits involved in sexual reproduction and diapause in the cyclically parthenogenetic freshwater rotifer, Brachionus calyciflorus, exposed to arsenic, a metalloid naturally found in high concentrations in desert zones, focusing on the effectiveness of diapause as an escape response in the face of an adverse condition. Addition of sublethal concentrations of arsenic modified the pattern of diapause observed in the rotifer: investment in diapause with arsenic addition peaked earlier and higher than in non-toxicant conditions, which suggests that sexual investment could be enhanced in highly stressed environmental conditions by increased responsiveness to stimulation. Nevertheless, eggs produced in large amount with arsenic, were mostly low quality, and healthy-looking eggs had lower hatching success, therefore it is unclear whether this pattern is optimum in an environment with arsenic, or if rather arsenic presence in water bodies disturbs the optimal allocation of offspring entering diapause. We observed high accumulation of arsenic in organisms exposed to constant concentration after several generations, which suggests that arsenic may be accumulated transgenerationally. The sexual phase in rotifers may be more sensitive to environmental conditions than the asexual one, therefore diapause attributes should be considered in ecotoxicological assessment because of its ecological and evolutionary implications on lakes biodiversity.

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“…11,No. Cecchine and Snell (1999) examined the combined effects of food level and either PCP or mercury on PGR in the rotifer Brachionus calyciflorus. 4.…”

Section: Results From Experimental Studiesmentioning

confidence: 99%

Toxicant Impacts on Density-Limited Populations: A Critical Review of Theory, Practice, and Results

Forbes

Sibly

Calow

2001

Ecological Applications

102

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Most natural populations experience some density dependence, and longterm average rates of population growth are likely to be close to zero (i.e., steady state). An essential question, therefore, is how and to what extent do density-dependent effects influence the responses of populations to toxicant impacts? Here we consider three general types of interaction between density dependence and toxicant effects: additive, less than additive, and more than additive. If we know enough about the life-history dynamics of an organism and how its life-history traits are affected by density and toxicant exposure, we should be able to use life-history models to predict responses of populations living under density-dependent control to chemical exposure. However, because the number of factors influencing the outcome is large, we demonstrate that simple, general, a priori predictions are not feasible. A review of the literature confirms that a variety of interactions has been observed in experimental systems. It is essential that experiments are designed so that the interactions of interest can be determined. We review these critically. Experimental designs that are appropriate for exploring density-toxicant interactions on individual physiological performance may be unable to detect potential compensatory interactions at the population level. Designs most likely to simulate the dynamics of field populations will be unable to determine the mechanistic bases underlying population-level impacts. To facilitate an ecologically correct interpretation of density-toxicant interactions, it is therefore essential that the limitations of the chosen experimental designs be recognized and made explicit.

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Toxicant exposure increases threshold food levels in freshwater rotifer populations

Cited by 23 publications

References 29 publications

Predicting the sensitivity of populations from individual exposure to chemicals: The role of ecological interactions

Predicting the sensitivity of populations from individual exposure to chemicals: The role of ecological interactions

Diapause as escape strategy to exposure to toxicants: response of Brachionus calyciforus to arsenic

Toxicant Impacts on Density-Limited Populations: A Critical Review of Theory, Practice, and Results

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