南极普里兹湾南极大磷虾资源时空分布与海洋环境要素的相关性

A correlation study between the marine environment and the spatial-temporal distribution of Antarctic krill(Euphausia superba Dana) in Prydz Bay

基于我国第29次南极科学考察在普里兹湾附近海域断面的调查,对2012年12月31日至2013年3月5日期间,普里兹湾南极大磷虾(Euphausia superba Dana)资源时空分布和资源量评估展开研究。结果表明,调查海域大磷虾平均资源密度为32.8 g/m2,总资源量为9.34×107 t;普里兹湾附近海域大磷虾资源量年度变化明显,种群年龄结构以2+龄或3+龄的补充群体为主,补充群体的生长状况将直接影响资源量变化;调查期间大磷虾主要集群于普里兹湾口的陆架坡折区,其范围为70.50°E^75.50°E、67°S^68.5°S,海底水深介于250~1 000 m;叶绿素浓度与大磷虾资源时空分布极显著相关(P<0.01),相关系数为0.193;未发现水温、盐度和海底水深与大磷虾资源时空分布的直接相关关系(P>0.05);盐度与叶绿素浓度呈显著负相关关系(P<0.01),相关系数为–0.23;叶绿素浓度深层极大值现象(简称DCM现象)出现在以73°E 67°S为中心的普里兹湾口附近海域,DCM现象可能与冬季残留水团关系密切。

Antarctic krill （Euphausia superba Dana） is a keystone species in the Southern Ocean ecosystem. Biomass and distribution research is important to further understand the Southern Ocean ecosystem and its relationship with environmental change. Krill biomass fluctuates annually in the Southern Ocean, and a relationship between extensive sea-ice cover during winter and subsequent high krill recruitment in the Antarctic Peninsula region has been suggested. Although many studies have investigated the effects of environmental factors （temperare, salinity, oxygen, and currents） on krill, except bathymetry of the shelf break and the presence of Circumpolar Deep Water near the Antarctic Peninsula, few studies have demonstrated a clear relationship between other factors and krill. Based on a transection survey conducted in the waters near Prydz Bay during the 29th Antarctic Chinese Scientific Expedition, continuous hy- droacoustic surveying and net sampling were conducted to estimate krill biomass and study the effects of the marine environment on krill spatial-temporal distribution. The environmental factors included water temperature, salinity, chlorophyll concentration, and bathymetry. The hydroacoustic instrument used was the 38 kHz SIMRAD EK500 （Norway）. The sampling net had a 15-mm mesh size. Environmental data were collected with the SBE-CTD911 instrument. The results showed that mean krill density in the survey area was 32.8 g/m2, and krill biomass was 9.34 million tons. The population age structure was mainly composed of the 2＋ and 3＋ recruitment groups, and the growing conditions during recruitment were the main reason for the annual changes in krill biomass. Krill aggregated primarily at the shelf break （70.50°E-75.50°E and 67°S-68.5°S） at 250-1000 m. A significant correlation （P〈0.01; t-=0.193） was found be- tween chlorophyll concentration and the spatial-temporal distribution of Antarctic krill. Temperature, salinity, and bathymetry did not correlate directly with the Antarctic krill spatial-temporal distribution（P〉0.05）. A significant nega- tive correlation was found between salinity and chlorophyll concentration （P〈0.01, r=-0.23）. The deep chlorophyll concentration maximum phenomenon （DCM） was found at 73°E and 67°S in the waters near Prydz Bay. The DCM may correlate with the winter residual water mass.