The horizontal and vertical distribution of phytoplankton in warm core ring 82B : a five month time series.
During the spring and summer of 1982, Gulf Stream warm core ring (WCR) 82B was sampled during four cruises from April to August, to investigate the changes in the phytoplankton flora with time. Discrete water samples from 28 stations were collected for identification and enumeration of phytoplankton...
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| Other Authors: | , , , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1987.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Summary: | During the spring and summer of 1982, Gulf Stream warm core ring (WCR) 82B was sampled during four cruises from April to August, to investigate the changes in the phytoplankton flora with time. Discrete water samples from 28 stations were collected for identification and enumeration of phytoplankton. Fourteen standard phytoplankton tows and fifteen 1/4 m² Multiple Opening/Closing Net and Environmental Sensing System (MOCNESS) net tows were taken at many of those stations to assess changes in the species composition of the larger, rarer phytoplankton components. The spring increase in WCR 82B occurred from late-April to mid-May and was multiphasic; early periods were dominated by the diatoms Minidiscus trioculatus (4-5 μm diam.) and a small Thalassiosira, possibly T. bulbosa, while later periods were dominated by a small (2-3 μm) biflagellate. In June, another diatom concentration was detected at ring center, but this one was dominated by Chaetoceros cf. vixvisibilis and Leptocylindrus danicus. Dinoflagellate and coccolithophorid maxima were situated slightly deeper than the diatom maximum, in the seasonal thermocline. The biomass maximum in a Shelf Water entrainment feature was compositionally distinct from the ring center biomass maximum. After interactions with and overwashes by the Gulf Stream in July, the ring had low numbers of all phytoplankton groups, and no single species dominated. Samples from ring center in August were similar in species abundance and composition to samples from the Slope Water, Sargasso Sea, and Gulf Stream. Analysis of net samples indicated that centric diatom species composition and relative abundance varied greatly between cruises. Chlorophyll maximum layers were more similar to surface layers from the same station than they were to chlorophyll maximum layers from other stations, based on species composition and relative abundance of centric diatoms. The chlorophyll maximum in WCR 82B represented a phytoplankton numerical abundance maximum in 70% of the profiles examined. Changes in phytoplankton abundance in the ring core occurred independently of changes in the surrounding Slope Water or in the source water, the Sargasso Sea. The ring center showed dramatic differences from its source water just 2 months after ring formation but remained distinct from the Slope Water for 4 months. |
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| Item Description: | Typescript (photocopy). Vita. |
| Physical Description: | xiii, 180 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references (leaves 165-175). |