温度对硬壳蛤Mercenaria mercenaria(Linnaeus,1758)呼吸排泄的影响

EFFECT OF TEMPERATURE ON RESPIRATION AND EXCRETION OF HARD CLAM MERCENARIA MERCENARIA (LINNAEUS, 1758)

于 2 0 0 2年 1 1月— 2 0 0 3年 4月 ,采用Winkle滴定法和次溴酸盐氧化法对硬壳蛤呼吸排泄进行了研究。结果表明 ,在 5— 35℃温度范围内 ,温度和体重对硬壳蛤 (壳长 0 5— 6cm ,软体部干重 0 0 0 34— 0 5 9g)的耗氧率和排氨率均有显著影响 (P <0 0 5 ) ,其单位体重耗氧率在2 0— 30℃之间达到最大值 ,且随着硬壳蛤个体的增大而下降 ;不同温度下硬壳蛤个体耗氧率OR[mgO2 /(ind·h) ]与软体部干重W(gDFW)之间的关系可用方程OR =aWb 表示 ,其中a值在0 0 4— 0 70之间 ,b值在 0 45— 0 65之间。硬壳蛤的排氨率 温度曲线呈单峰型 ,其单位体重排氨率在 2 5℃附近达到最大值 ,且随着硬壳蛤个体的增大而下降。不同温度下硬壳蛤个体排氨率NR[μgNH4 N/(ind·h) ]与软体部干重W(gDFW)之间的关系可用方程NR =aWb 表示 ,其中a值在 1— 2 7之间 ,b值在 0 40— 0 75之间。硬壳蛤呼吸排泄的氧、氮比在 5℃时最大 ,随后有下降趋势 ,其比值在 1 0— 80之间。

Hard clam Mercenaria mercenaria belongs to Veneridae,Venus clam,Lamillibranchia.Its natural distribution ranged from the gulf of St.Lawrence along the east coast of the United States to the gulf coast of Texas,and it was introduced into China for the first time by Institute of Oceanology,Chinese Academy of Sclences in 1997.M.mercenaria had a high adaptability to the habitat,and can live in vast temperature and salinlty range with high growth rate,and can teach commodity specification (shell length>4.5cm) within two years,so M.mercenaria. is an excellent economic species.It was bred successfully in these years and have a very good prospect in China.There is many sudy about the respiration and excretion of M.mercenaria,but there is seldom repon in this aspect in China.This report discussed the effect of temperature and weight on the respiration and excretion of M.mercenaria.In order to leam more about the variation of ecophysiology about M.mercenaria and the basic data of this clam after it was introduced to China. Clam in good condition were selected and separated into four gronps by shell lensth:A(4—6cm),B(2.4—2.6cm),C(1.4—1.6cm),D(0.5—1cm),cultured in tank temporary for study,and fed with Phaeodactylum tricornutum and aerated daily. The research was performed in laboratory from Nov,2002 to Apr,2003 on respiration and excretion of M. mercenaria, using Winkle titration and hypobromate oxidation method,which provlded some basic data for artificial bteeding,aquiculture and the assessment of aquiculture capability.Reuslts indicated that temperature and clam dry flesh weight (DFW,60℃,24h) had significant effect (P<0.05) on oxygen consumption and ammonia-N excretion rate of M.mercenaria (shell length ranged from 0.5cm to 6cm,DFW ranged from 0.0034g to 0.5000g).The oxygen consumption rate per gram DFW reliched its maximum between 20℃ and 30℃ in natural seawater,and decreased with M.mercenaria weight increased.The relationship between individual oxygen consumption rate and its DFW under different temperature could be expressed by OR=aW b,where OR is oxygen consumption rate.[mgO 2/ (ind·h)],W is individual dry fresh weight(g),and a ranged from 0.04 to 0.70,b ranged from 0.45 to 0.65; the ammonia-N excretion rate-temperature curve was unimodal.The maximum ammonia-N excretion rate per gram DFW was abont 25℃,and decreased with M.mercenaria weight increased.The relationship between individual ammonia-N excretion rate and its DFW under different temperatute could be expressed by NR=aW b,where NR is ammonia-N excretion rate [μgNH 4-N/ (ind·h)],W is individual dry fresh weight (g),and a ranged from 1 to 27, b ranged from 0.40 to 0.75.The atomic ratio of O and N had an maximum at abont 5℃,and declinad as temperature rised,and its value was between 10 and 80.