普里兹湾邻近海域长臂樱磷虾数量分布与发育特点的研究

DISTRIBUTION ,ABUNDANCE AND REPRODUCTIVE ECOLOGY OF THYSANOESSA MACRURA (CRUSTACEA:EUPHAUSIACEA) IN THE PRYDZ BAY REGION,ANTARCTICA

198 9/1 990和 1 990 /1 991南极夏季期间 ,在南印度洋普里兹湾邻近海域进行了调查 ,对这一海域长臂樱磷虾 (Thysanoessa macrura G.O.Sars)成体和幼体的数量分布和生殖、发育特点进行了研究。长臂樱磷虾出现在整个测区。成体主要密集在南极辐散带 ,幼体几乎出现在每个测站。1月份 ,长臂樱磷虾幼体在磷虾幼体中数量最多 ,1 990年 1月平均为 744个 /1 0 0 0 m3 ,1 991年 1月平均为 1 1 5 5个 /1 0 0 0 m3 。幼体数量外海多 ,陆架、陆坡区少。成体与幼体数量的东西向分布与饵料深度呈正相关 ,测区中部的密度要高于测区东西两端。幼体发育有自北向南 ,随纬度升高 ,发育程度逐渐降低的趋势。1 990年幼体发育期组成 ,1月上旬为 C1 - F2 ,幼体平均发育期指数为 2 .78;2月下旬为 C2 - F5 ,平均发育期指数为 4.89;3月上旬为 C3 - F6 ;平均发育期指数为 5 .0 0。1 991年幼体发育组成 ,1月上旬为 C1 - F3 ,平均发育期指数为 3 .75 ;3月上旬为 F1 - F6 ,平均发育期指数为 8.70。原蚤状幼体和蚤状幼体的平均发育速度 ,1 989/1 990年为 1 3 - 1 9天 /期 ,1 990 /1 991年为 1 1天 /期。在调查海域 ,长臂樱磷虾约 1 0月上旬开始产卵 ,1月上旬产卵基本结束。1 991年 1月份成体及未成体的体长组成主要分布在 1 0 - 2 0毫?

During the austral summer of 1989/1990 and 1990/1991 net sampling survey was carried out on the distribution,abundance,age-composition,development and reproductive ecology of Thysanoessa macrura G.O.Sars in the prydz Bay region.Larvae occurred throughout the research areas with comparatively high abundance. The average density of larvae was 744 ind./1000m 3 in Jan.1990 and 1155 ind./1000m 3 in Jan.1991.They were more abundant in open ocean area than in slop and shelf areas.In 1990, the larval developmental stages from C1 to F2 were found in early Jan.with the mean stage index (MSI) equal to 2 78. In late Feb.they were substituted by C2-F5 (MSI=4.89),and in early March C3-F6(MSI=5.00).More advanced developmental larval stages were found in 1991,C1-F3(MSI=3 75) in early Jan.and F1-F6(MSI=8.70) in early March. Latitudinal difference in larval developmental stage composition or in MSI could be clearly found,i.e.the closer to the shelf the younger of the larvae.The mean developmental time from stage to stage by field data was 13-19 days in 1989/1990 and 11 days in 1990/1991.The main breeding season of T.macrura in Prydz Bay area seemed to start in early October and end in early January.Adults and Juveniles were widely dispersed,but swarms were found mainly close to the Antarctic Divergency.Inter-annual variations in timing of breeding ,survival of larvae and abundance of adults were evident.More advanced larval stages,which means an earlier breeding season,shorter developmental time for larval stages,and more abundant adults and juveniles were observed in 1990/1991.These might be attributed to the warmer water temperature compared with 1989/1990.