Dividing mesozooplankton into upper and lower size groups: Applications to the grazing impact in the Marginal Ice Zone of the Barents Sea

作者：Pasternak Anna^*; Arashkevich Elena; Reigstad Marit; Wassmann Paul; Falk Petersen Stig

来源：Deep Sea Research Part II: Topical Studies in Oceanography , 2008, 55(20-21): 2245-2256.

DOI：10.1016/j.dsr2.2008.05.002

• Abundance
• Biomass
• Grazing
• Zooplankton
• Size groups
• Barents Sea

Microzooplankton (20-200 mu m) are now regarded as major grazers of phytoplankton, as opposed to mesozooplankton (0.2mm-2cm). A group of plankton animals of 100-500 mu m body length is not, however, properly assessed because these plankters are not sufficiently abundant to be adequately sampled with microzooplankton methods, but too small to be quantitatively sampled with standard plankton nets. We distinguished a group of "sub-mesozooplankton" (SMZ), comprised ubiquitous and abundant Oithona spp., other small copepods, nauplii of various crustaceans, younger copepodites, meroplankton. Abundance, biomass and grazing impacts of SMZ and mesozooplankton in the pelagic community of the marginal ice zone of the Barents Sea were compared during three cruises of the CABANERA project. Sampling with plankton nets resulted in substantial and highly variable underestimation of SMZ. Further comparisons were done between mesozooplankton collected with 180-mu m mesh nets and SMZ with 30-1 Niskin bottles. Abundance of SMZ exceeded that of mesoplankton by a factor of 4-56, while biomass comprised from 10% to 87% of mesozooplank-ton biomass at different stations. Grazing was assessed from gut fluorescence and gut passage time. Grazing impacts of SMZ and mesoplankton were comparable (sometimes equal). Persistent greater abundance of SMZ and its higher metabolic rates were responsible. The role of SMZ in trophodynamics of pelagic community was considerable and varied greatly depending on species and stage composition of plankton. Larval stages of both plankton and benthic invertebrates played the major role in grazing pressure exerted by SMZ.

• 出版日期2008-10
• 单位中国极地研究中心