| Nonylphenol was classified as environmental endocrine disrupter for the capability oninterfering with hormonal system. Nonylphenol was xenobiotic compound originated from thedegradation of nonylphenol ethoxylates which was widely used in industrial, commercial,angricultural and household applications. Due to the low solubility and high hydrophobicity ofthose by-products, nonylphenol, became ubiquitous in the air, surface water, soil and sediments,especially sewage sludge and surface water sediments. Nonylphenol showed certain acutetoxicity, such as decrease survival and moulting rate of juveniles, fertility in maturation period.Moreover, disrupting effect through mimicing hormones and disturbing the signals that regulatephysiology attracted considerable attention around the world. However, responses of differentorganisms treated with nonylphenol were diverse and unpredictable especially under series ofculture conditions. This paper focused on the potential chronic impacts of nonylphenol onfreshwater cladocerans, especially on growth and reproduction. Bioaccumulation of nonylphenolin different species of algae was studied in order to better understand transportation of lowsoluble nonylphenol into biological food chains. Grazing efficiency of five cladoceran specieswere studied by feeding eleven algaes with two cell densities. Chronic effects were studiedthrough direct and dietary exposure of nonylphenol fed with eleven algae species, whilemuitigeneration impact was compared with recovery treatment fed with three algae species. Thedata supports the need for evaluation and monitor the potential long-term environmental impactof nonylphenol systematically.Survival and feeding rate were influenced by density, structure, size and quality of algaesignificantly. Decrease of survival rate and feeding ability was detected as algae density up to“water bloom” level. Filtration rate was influenced negatively as the increase of cell density, sizeand assembling conditions. Grazing rate and flitration rate decreased at Pediastrum sp., S. quadricanda, Scenedesmus sp.treatments. Inhibitory effect of size and structure on larves couldbe released by nutrient quality, such as content of unsaturated fatty acid, which was consideredto be key limiting factor. Higher grazing rate in Monia dued to the short larve phase comparedwith that in Daphnia.The half-dampening effect concentration of nonylphenol on eleven species at96h was among0.6-3.33mg/l, which was influenced by both growth rate and tolerance. Bioconcentration ofnonylphenol was detected evidently in all species, while the maximum Bioaccumulation factorswere8313and13190at1h and12h respectively. Biosorption at the initial phase was co-relatedwith total surface areas, while in the latter phase was determined by physiological activity, suchas photosynthetic and metabolic activities.The half letal concentration of nonylphenol on five cladoceran species at48h was among8.67-131.79μg/l in acute toxicity, tolerance of Monia was higher than Daphnia evidently.Chronic toxicity were detected by decrease of survival rate, life expectation, net reproductiverate, intrinsic growth rate and lag time of first reproduction as the increase of initial nonylphenolconcentrations on three cladoceran species. Regardless of feeding species, D. magna was moresensitive than M. macrocopa and M. micrura. Feeding with eleven algae species, toxicity ofnonylphenol was reduced under S. obliquus, Selenastrum sp., Microcystis sp. treatments, whileenhanced under Pediastrum sp., S. quadricanda, A. convolutes, Scenedesmus sp.,Chlamydomonas sp. treatments.Life history traits of five cladoceran species were influenced by dietary exposure evidently,enhancement of toxicity was detected as the increase of algae exposed time. Total number ofoffspring per female, the time to first brood, life expectation, net reproductive rate, intrinsicgrowth rate showed significant reduction. Life expectation was increased while net reproductiverate was decreased in dietary exposure treatment compared with equal amount of nonylphenoldirect exposure treatments. Dietary exposure of nonylphenol with eleven algae species, toxicityof nonylphenol on life expectation and net reproductive rate was reduced under Selenastrum sp.,S. obliquus, Microcystis sp. treatments. Life history traits of D. magna fed with S. obliquus andM. macrocopa fed with Selenastrum sp. showed no notable difference compared with control.Influence of nonylphenol through dietary exposure on M. macrocopa was more adverse than thaton D. magna, which indicated that higher grazing rate in the larvae induced higher accumulation and toxicity.Multigeneration exposure induced increase or decrease of sensitivity dependented onnonylphenol concentrations, cladoceran species and feeding algae species. D. magna exposed to1and0.01ug/l nonylphenol decreased the life expectation and net reproductive rate in both firstand third broods compared with parentals in three feeding species. Exposed to0.01ug/nonylphenol with S. obliquus, Microcystis sp. and l ug/l treatments, growth and reproduction of M.macrocopa were inhibited over successive generations. Moreover, life expectation and netreproductive rate of offsprings in the recovery treatments were still reduced evidently comparedwith parental treatments and control. However, growth and reproduction were promoted in thefirst and third broods under0.01ug/l nonylphenol exposure fed with Selenastrum sp.. Lifeexpectation and net reproductive rate of offsprings in exposure and recovery treatments wereenchanced significantly, which indicated that low dose and suitable food supplement inducedparental acclimation or adaptation, then higher physiological activity in offsprings.Bioaccumulation of nonylphenol in algae was dependented on both morphology andphysiology characters, which should be pay much more attention for a fully understanding.Disturbering effect was detected in growth and reproduction exposed one or two orders ofmagnitude lower than the threshold in freshwater, especially under successive generationexposure treatments. Bioconcentration of nonylphenol illustrated efficient pathway to enter foodchain, which might be more toxic as the concentration increase thousands of times comparedwith that in water. Effect of nonylphenol on cladoceran was influenced by feeding algae specie,such as structure, size and nutrient quality, which indicated the complexity regulation ofnonylphenol in aquatic system. |
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