The role of the euthecosome pteropod, limacina retroversa, in the polar frontal zone, Southern Ocean
The aim of the present study was to assess the ecological role of the euthecosome pteropod, Limacina retroversa, in particular, and the mesozooplankton community, in general, in the pelagic ecosystem of the Polar Frontal Zone (PFZ), Southern Ocean. Data were collected from four oceanographic surveys...
Main Author: | |
---|---|
Format: | Doctoral or Postdoctoral Thesis |
Language: | English |
Published: |
Rhodes University
2007
|
Subjects: | |
Online Access: | http://hdl.handle.net/10962/d1005449 https://corycommons.ru.ac.za/vital/access/manager/Repository/vital:5761 |
id |
ftrhodesunivcory:vital:5761 |
---|---|
record_format |
openpolar |
spelling |
ftrhodesunivcory:vital:5761 2023-05-15T13:57:15+02:00 The role of the euthecosome pteropod, limacina retroversa, in the polar frontal zone, Southern Ocean Bernard, Kim Sarah 2007 220 leaves pdf http://hdl.handle.net/10962/d1005449 https://corycommons.ru.ac.za/vital/access/manager/Repository/vital:5761 English eng Rhodes University Faculty of Science, Zoology and Entomology vital:5761 https://corycommons.ru.ac.za/vital/access/manager/Repository/vital:5761 http://hdl.handle.net/10962/d1005449 Bernard, Kim Sarah Pteropoda Limacidae Zooplankton -- Antarctic Ocean Copepoda Phytoplankton Thesis Doctoral PhD 2007 ftrhodesunivcory 2022-12-26T13:33:57Z The aim of the present study was to assess the ecological role of the euthecosome pteropod, Limacina retroversa, in particular, and the mesozooplankton community, in general, in the pelagic ecosystem of the Polar Frontal Zone (PFZ), Southern Ocean. Data were collected from four oceanographic surveys to the Indian sector of the PFZ during austral autumn 2000, 2002, 2004 and 2005. Copepods, mainly Calanus simillimus, Oithona similis, Clausocalanus spp. and Ctenocalanus spp., typically dominated total mesozooplankton counts, accounting for, on average, between 75.5 % and 88.1 % (Mean = 77.4 %; SD = 13.4 %) of the total, during the present investigation. Results of the study indicate that L. retroversa may, at times, contribute substantially to total mesozooplankton abundances. During the study, L. retroversa contributed between 0.0 and 30.0 % (Mean = 5.3 %; SD = 7.1 %) to total mesozooplankton numbers. Significant small-scale variability in abundance and size structure of L. retroversa and abundance of copepods was minimal. Inter-annual variability, on the other hand, was significant between some years. Total pteropod numbers were greatest during April 2002 and 2004, while copepods exhibited greatest abundances during April 2004 only. Pearson’s Correlation analysis suggested that L. retroversa abundances were positively correlated to total surface chlorophyll-a (chl-a) concentrations. The significantly lower chl-a concentrations recorded during April 2005 may explain the reduced pteropod numbers observed during that survey. The size class structure of L. retroversa comprised mainly small and mediumsized individuals during all four surveys. This corresponds well with records from the northern hemisphere (sub-Arctic and Arctic waters) where Limacina spp. are reported to exhibit maximum spawning during mid to late-summer. Higher abundances of large individuals only occurred during April 2005, when chl-a concentrations were very low; possibly the result of delayed spawning, due to reduced food availability. Ingestion ... Doctoral or Postdoctoral Thesis Antarc* Antarctic Antarctic Ocean Arctic Mesozooplankton Phytoplankton Southern Ocean Zooplankton Copepods Rhodes University Cory: Repository Antarctic Antarctic Ocean Arctic Austral Indian Southern Ocean |
institution |
Open Polar |
collection |
Rhodes University Cory: Repository |
op_collection_id |
ftrhodesunivcory |
language |
English |
topic |
Pteropoda Limacidae Zooplankton -- Antarctic Ocean Copepoda Phytoplankton |
spellingShingle |
Pteropoda Limacidae Zooplankton -- Antarctic Ocean Copepoda Phytoplankton Bernard, Kim Sarah The role of the euthecosome pteropod, limacina retroversa, in the polar frontal zone, Southern Ocean |
topic_facet |
Pteropoda Limacidae Zooplankton -- Antarctic Ocean Copepoda Phytoplankton |
description |
The aim of the present study was to assess the ecological role of the euthecosome pteropod, Limacina retroversa, in particular, and the mesozooplankton community, in general, in the pelagic ecosystem of the Polar Frontal Zone (PFZ), Southern Ocean. Data were collected from four oceanographic surveys to the Indian sector of the PFZ during austral autumn 2000, 2002, 2004 and 2005. Copepods, mainly Calanus simillimus, Oithona similis, Clausocalanus spp. and Ctenocalanus spp., typically dominated total mesozooplankton counts, accounting for, on average, between 75.5 % and 88.1 % (Mean = 77.4 %; SD = 13.4 %) of the total, during the present investigation. Results of the study indicate that L. retroversa may, at times, contribute substantially to total mesozooplankton abundances. During the study, L. retroversa contributed between 0.0 and 30.0 % (Mean = 5.3 %; SD = 7.1 %) to total mesozooplankton numbers. Significant small-scale variability in abundance and size structure of L. retroversa and abundance of copepods was minimal. Inter-annual variability, on the other hand, was significant between some years. Total pteropod numbers were greatest during April 2002 and 2004, while copepods exhibited greatest abundances during April 2004 only. Pearson’s Correlation analysis suggested that L. retroversa abundances were positively correlated to total surface chlorophyll-a (chl-a) concentrations. The significantly lower chl-a concentrations recorded during April 2005 may explain the reduced pteropod numbers observed during that survey. The size class structure of L. retroversa comprised mainly small and mediumsized individuals during all four surveys. This corresponds well with records from the northern hemisphere (sub-Arctic and Arctic waters) where Limacina spp. are reported to exhibit maximum spawning during mid to late-summer. Higher abundances of large individuals only occurred during April 2005, when chl-a concentrations were very low; possibly the result of delayed spawning, due to reduced food availability. Ingestion ... |
format |
Doctoral or Postdoctoral Thesis |
author |
Bernard, Kim Sarah |
author_facet |
Bernard, Kim Sarah |
author_sort |
Bernard, Kim Sarah |
title |
The role of the euthecosome pteropod, limacina retroversa, in the polar frontal zone, Southern Ocean |
title_short |
The role of the euthecosome pteropod, limacina retroversa, in the polar frontal zone, Southern Ocean |
title_full |
The role of the euthecosome pteropod, limacina retroversa, in the polar frontal zone, Southern Ocean |
title_fullStr |
The role of the euthecosome pteropod, limacina retroversa, in the polar frontal zone, Southern Ocean |
title_full_unstemmed |
The role of the euthecosome pteropod, limacina retroversa, in the polar frontal zone, Southern Ocean |
title_sort |
role of the euthecosome pteropod, limacina retroversa, in the polar frontal zone, southern ocean |
publisher |
Rhodes University |
publishDate |
2007 |
url |
http://hdl.handle.net/10962/d1005449 https://corycommons.ru.ac.za/vital/access/manager/Repository/vital:5761 |
geographic |
Antarctic Antarctic Ocean Arctic Austral Indian Southern Ocean |
geographic_facet |
Antarctic Antarctic Ocean Arctic Austral Indian Southern Ocean |
genre |
Antarc* Antarctic Antarctic Ocean Arctic Mesozooplankton Phytoplankton Southern Ocean Zooplankton Copepods |
genre_facet |
Antarc* Antarctic Antarctic Ocean Arctic Mesozooplankton Phytoplankton Southern Ocean Zooplankton Copepods |
op_relation |
vital:5761 https://corycommons.ru.ac.za/vital/access/manager/Repository/vital:5761 http://hdl.handle.net/10962/d1005449 |
op_rights |
Bernard, Kim Sarah |
_version_ |
1766264845698596864 |