北极拉普捷夫海春季冰藻和浮游植物群落结构及生物量分析

COMMUNITY STRUCTURE AND BIOMASS OF ICE ALGAE AND PHYTOPLANKTON IN THE LAPTEV SEA(ARCTIC) IN SPRING

对1999年春季采集于北极拉普捷夫海东南部的冰藻和冰下浮游植物群落的种类组成进行了分析,并对丰度和生物量进行了统计和对比。藻种以硅藻占绝对优势,其中又以羽纹硅藻为主。优势种集中,主要包括海洋拟脆杆藻(Fragilariopsisoceanica)、圆柱拟脆杆藻(F.cylindrus)、寒冷菱形藻(Nitzschiafrigida)、普罗马勒菱形藻(N. promare)、带纹曲壳藻(Ach nanthestaeniata)、新寒冷菱形藻(Nitzschianeofrigida)、大洋舟形藻(Naviculapelagica)、范氏舟形藻(N. vanhoeffenii)、北极直链藻(Melosiraarctica)、北方舟形藻(N. septentrionalis)、新月细柱藻(Clindrothecaclosterium)和绿藻门的塔形藻(Pyramimonassp. )。微藻主要集中在冰底10cm,丰度为14. 6—1562. 2×104 cells·L-1,平均为639. 0×104 cells·L-1;生物量为7. 89—2093. 5μgC·L-1,平均为886. 9μgC·L-1,总体上比次冰底高1个数量级,比冰下表层水柱高2个数量级。冰底20cm冰柱的累计丰度和生物量平均分别为冰下20m水柱累计量的7. 7和12. 2倍,显示冰藻在春季海冰融化前在近岸生态系统中的重要作用。尽管各站位冰底和冰下表层水柱藻类群落的相似性普遍不高,但整个调查海域冰底和冰下水柱优势种极为相似,春季期间冰藻对冰下浮游植物群落的影响明显。由于?

Species composition, abundance and biomass of ice algal and underlying phytoplankton communities were investigated in southeastern Laptev Sea in spring 1999. Diatoms were predominant in algal species and pennate diatoms were dominant in diatom species. 12 dominant algal species occurred in ice and underlying water column, which included Fragilariopsis oceanica, F. cylindrus, Nitzschia frigida, N. promare, Achnanthes taeniata, Nitzschia neofrigida, Navicula pelagica, N. vanhoeffenii, N. septentrionalis, Melosira arctica, Clindrotheca closterium and Pyramimonas sp. The algal abundance within bottom 10cm sea ice were between 14.6 and 1562.2 ×10 4 cells·L -1 with an average of 639.0 ×10 4 cells·L -1 , and the algal biomass were between 7.89 and 2093.5 μg C·L -1 with an average of 886.9 μg C·L -1 , which were about one magnitude higher than those of sub-bottom and two magnitude higher than those of underlying surface water. The integrated algal abundance and biomass within bottom 20cm ice column were averagely 7.7 and 12.2 times as those in underlying 20m water column, respectively, suggesting that the ice algae might play an important role in maintaining the coastal marine ecosystem before the melting of sea ice. The influence of ice algae to the phytoplankton community was obvious although the similarities of algal community in ice bottom and water surface were not high in many sites. But the “seeding” of ice algae to phytoplankton was low because the abundance and biomass in water column were much lower than those in bottom ice and no rapid growth occurred within phytoplankton community.