Inter-annual variation in summer zooplankton community structure in Prydz Bay, Antarctica, from 1999 to 2006 |
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Authors: | Guang Yang Chaolun Li Song Sun |
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Institution: | (1) Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, 7 Naihai Road, Qingdao, 266071, People’s Republic of China;(2) Graduate University, Chinese Academy of Sciences, 19 Yuquan Road, Beijing, 100049, People’s Republic of China; |
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Abstract: | Inter-annual variations in zooplankton community structure in Prydz Bay were investigated using multivariate analysis based
on samples collected with a 330-μm mesh, 0.5-m2 Norpac net during the austral summer from 1999 to 2006. Two distinct communities, an oceanic and a neritic community, were
consistently identified in all surveys. Oceanic communities had higher diversity and were indicated by species such as Haloptilus ocellatus, Heterorhabdus austrinus, Thysanoessa macrura, Rhincalanus gigas, Scolecithricella minor and Oikopleura sp.. Neritic communities were indicated by Euphausia crystallorophias and Stephos longipes and were characterized by fewer but more abundant species. In 1999 and 2006, a transitional community was also distinguished near the continental shelf edge, where ice coverage was
more extensive than either the oceanic or neritic regions. Significant inter-annual variations in community structure (mainly
involving species abundance rather than species composition) were found in both oceanic and neritic communities, being more
obvious in the latter. The timing and amplitude of sea ice retreat (polynya appearance), and its effect on food availability,
had strong influences on zooplankton community structure. In oceanic communities during years with earlier ice retreat, the
extra time available for phytoplankton blooms to accumulate resulted in a higher proportion of large copepods (Calanoides acutus, Calanus propinquus, Metridia gerlachei) (especially the younger copepodites) in the zooplankton assemblage. In neritic communities, zooplankton such as the ice
krill E. crystallorophias, and large copepods (C. acutus, C. propinquus, M. gerlachei), also showed higher abundance and earlier developmental stages in years with larger polynya. On the other hand, in years
with later ice retreat, smaller polynya, and less time for phytoplankton blooms to form, the abundance of large copepods was
lower and older age classes were more common. |
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