The autumn mesozooplankton community at South Georgia: biomass, population structure and vertical distribution
Mesozooplankton were sampled at shelf and oceanic stations close to South Georgia, South Atlantic during austral autumn 2004 with a Longhurst Hardy Plankton Recorder. Onshelf biomass ranged from 2.18 to 5.75 g DM m−2 (0–200 m) and was dominated by the small euphausiid Thysanöessa spp. At the oceanic...
| Published in: | Polar Biology |
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| Main Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | unknown |
| Published: |
Springer
2006
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| Subjects: | |
| Online Access: | http://nora.nerc.ac.uk/id/eprint/1048/ https://doi.org/10.1007/s00300-006-0136-3 |
| Summary: | Mesozooplankton were sampled at shelf and oceanic stations close to South Georgia, South Atlantic during austral autumn 2004 with a Longhurst Hardy Plankton Recorder. Onshelf biomass ranged from 2.18 to 5.75 g DM m−2 (0–200 m) and was dominated by the small euphausiid Thysanöessa spp. At the oceanic stations (10.57–14.71 g DM m−2, 0–1,000 m) large calanoids, principally Rhincalanus gigas comprised ∼47–52% of biomass. Here Calanus simillimus was still active and reproducing in surface waters (0–11.2 eggs fem day−1) but R. gigas and Calanoides acutus were largely resident in the warm deep water and undergoing their seasonal descent. A comparison with spring and summer data indicated increased abundance and biomass from spring through to summer followed by a decline towards autumn particularly over the shelf. Autumn values in oceanic waters differed little from summer. Mesozooplankton biomass in the surface 200 m of the oceanic stations as a proportion of that found in the top 1,000 m ranged from 63 to 78% of the total in spring and 62–73% in summer, but was only 23–29% of the total in this study, following redistribution down the water column. |
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