MEPS 434:77-90 (2011) - doi:10.3354/meps09188
Metazooplankton community structure, feeding rate estimates, and hydrography in a meltwater-influenced Greenlandic fjord
Kam W. Tang1,*, Torkel Gissel Nielsen2, Peter Munk2, John Mortensen3, Eva Friis Møller4, Kristine Engel Arendt3, Kajsa Tönnesson5, Thomas Juul-Pedersen3
ABSTRACT: In order to assess the potential responses of Greenland’s coastal ecosystems to future climate change, we studied the hydrography and distribution of metazooplankton, along a transect from the slope waters beyond Fyllas Banke to the inner part of Godthåbsfjord, West Greenland, in July and August 2008, and estimated feeding rates for some of the larger species groups. Within the 4 regional domains that were covered in the study (continental slope, continental shelf, outer sill region, and main fjord basin), salty coastal water and glacial runoff mixed to various extents, and 7 water masses with specific characteristics were identified. The common large copepod species were Calanus finmarchicus, C. glacialis, C. hyperboreus, and Metridia longa. Small copepod genera included Microsetella, Pseudocalanus, and Oithona, while rotifers and gastropods (primarily pteropods) were also found in high abundance. Species could be linked to the specific water masses, e.g. Calanus spp. were primarily associated with oceanic or coastal waters, whereas M. longa, Microsetella sp., Pseudocalanus sp., and rotifers were mostly found inside the fjord. The combined biomass of the large zooplankton species (5.5 × 103 mg C m–2) was less than that of the small species (6.8 × 103 mg C m–2) averaged across all sampled stations along the transect. Estimated in situ grazing rates for the large copepod species were <10% of their maximum rates, indicating food limitation. The major predatory zooplankton groups, Pareuchaeta norvegica and chaetognaths, had estimated predation effects of <1% d–1 on the prey community. The dominance of small zooplankton species within the fjord contradicts the traditional emphasis on large, lipid-rich zooplankton species in the arctic seas, and suggests that the planktonic food web structure inside the glacial fjord was different from that of the system outside.
KEY WORDS: Glacial fjord · Greenland · Climate change · Copepod · Grazing · Predation · Food web
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