Stoichiometry And Maternal Effect In Pseudodiaptomus Annandalei Under Different Nitrogen And Phosphorus Conditions

Marine planktonic copepods are inter-mediate organisms in the marine planktonic food chain,and thus play important roles in the marine ecosystem. Change in the elemental composition,mainly nitrogen and phosphorus, one important aspect of changes in marine environment, isresulted into the degraded nutrient quality of phytoplankton as the preys of zooplankton.Consequently, this will potentially impair the growth, reproduction, elemental and biochemicalcompositions of the grazer of phytoplankton and further the function of the whole marineecosystem. Therefore, it is significant to study the mechanisms for the limitation and adaptationunder nitrogen and phosphorus deficiency. Pseudodiapomus annandalei, the common species ofpanktonic copepod in the coast area to the southeast of China was chosen as the experimentalorganism in this study. The stoichiometric characteristics, composition of fatty acids andmaternal effects of P. annadalei under contrasting N and P conditions to elucidate themechanisms for the limitation and adaptation under nitrogen and phosphorus deficiency. Themain results are as following:（1） Nitrogen content of adult of P. annandalei feeding on Tetraselmis subcordiformis （molarC/N=35or46） with low N content （molar N/P=0.2or0.8） is2.57³.29x10^-1μg·ind.^-1,significantly lower than those body (7.48x10^-1μg·ind.^-1) feeding on Tetraselmis subcordiformis（molar C/N=5） under high nitrogen condition （molar N/P=24）, at the same time, phosphoruscontent of adult is less than that under high nitrogen condition. Under the different nitrogenconditions, reproductive rate of female body have significant differences, Spawn rate (14¹5eggs·ind.^-1) under low nitrogen conditions is far lower than the high nitrogen condition with19eggs·ind.^-1; Nauplius length also have significant difference, the body length （152¹56μm） underlow nitrogen conditions is far lower than that （179μm）under the high nitrogen condition.Nitrogen content of nauplius is2.82².94x10-2μg·ind.^-1, significantly lower than that(3.44x10-2μg·ind.^-1) under high nitrogen conditions, but phosphorus content is significantlyhigher than the high nitrogen condition; Into the copepodid length, time, and growth rates of thebabies have significant difference, body length （433⁴53μm） and growth rate （0.204⁰.217） oflow nitrogen is much higher than high nitrogen conditions of375μm and0.115, but time （5 ⁵.13days） is far lower than the high nitrogen （6.38days）; And into copepodid under theenvironment with high nitrogen, body length and growth rate have significant difference, bodylength （460⁴80μm） and growth rate （0.171⁰.185） into copepodid is far higher than that（375μm and0.115）under high nitrogen conditions.（2） Phosphorus content of adult of P. annandalei feeding on Tetraselmis subcordiformis （molarC/P=176or190） with low P content （molar N/P=779or3117） is3.1³.69x10-2μg·ind.^-1,significantly lower than those body (6.52x10-2μg·ind.^-1) feeding on Tetraselmis subcordiformis（molar C/P=29） under high phosphorus condition （molar N/P=24）, at the same time, nitrogencontent of adult is less than that under high phosphorus condition. Under the differentphosphorus conditions, reproductive rate of female body have significant differences, Spawnrate (12¹4eggs·ind.^-1) under low phosphorus conditions is far lower than that (19eggs·ind.^-1)under high phosphorus condition; Nauplius length also have significant difference, the bodylength （153¹60μm） of low phosphorus conditions is far lower than that （179μm） under highphosphorus condition. Phosphorus content of nauplius is (1.36¹.55x10^-3μg·ind.^-1), significantlylower than that (2.13x10^-3μg·ind.^-1) under high phosphorus conditions; Into the copepodidlength, time, and growth rates of the babies have significant difference, body length （403⁴23um） and time （10.9¹2.4days） of low phosphorus is much higher than that （375μm and6.38days） under higher phosphorus conditions, but growth rate （0.088⁰.094） is far lower than thehigh phosphorus condition （0.115）; And into copepodid under the environment of highphosphorus, body length and time and growth rate have significant difference, body length（420⁴45μm） and time （7.25⁷.63days） and growth rate （0.138⁰.148） into copepodid is farhigher than that （375μm,6.38days and0.115） under high phosphorus conditions.（3） Comprehensive experimental results under different nitrogen and phosphorus conditions,we further analyzed the female body, the nauplius and the algal cells of correlation betweenelements and fatty acids, found that: N content of the female body has a significant correlation（p=0.026） with nauplius; P content of nauplius has a significant correlation （p=0.0031） withalgae cells,24-0fatty acids of nauplius have significant correlation （p=0.0412） with algae cells,N content has a certain relevance （p=0.0658）; N content of female body has a significantcorrelation （p=0.0033） with algae cells,20-4fatty acids of female body has a significantcorrelation （p=0.036） with algae cells,18-3-6fatty acids of female body has a significant correlation （p=0.0449） with algae cells.In conclusion, the breed of the female body is restrained, the nauplius has lower content ofnitrogen and phosphorus under low nitrogen and low phosphorus conditions. The growth rateand development of nauplius is different under the condition with enough nitrogen andphosphorus, presented different development characteristics. Under the lack of nitrogencondition is speeding up of the development characteristics, the length of nauplius produced bythe female body under low nitrogen into the larval stage increased, and shortened developmenttime; In the recovery experiments, nauplius produced by low nitrogen female body in feeding onalgal cells with enough nutrition, have higher growth rate than normal conditions. Slowdevelopment under the condition of phosphorus deficiency; In the recovery experiments,nauplius produced by low phosphorus female body in feeding on algal cells with enoughnutrition, have a same growth rate with normal conditions. Show that low nitrogen andphosphorus for populations impact of copepods is reversible, under the influence of low nitrogenand low phosphorus stress of population, when the environment conditions improved, copepodscan obtain high growth rate quickly, therefore, is a kind of adaptation mechanisms for adversity.