The community structure and predation impact of carnivorous macrozooplankton (>2 cm; chaetognaths, medusae, ctenophores and mysids), with particular emphasis on the chaetognaths Eukrohnia hamata and Sagitta gazellae, were investigated during three surveys conducted in late austral summer (April/May) of 2001, 2004 and 2005 in the Polar Frontal Zone in the vicinity of the Prince Edward Islands (46º45’S, 37º50’E), Southern Ocean. The 2001 survey formed part of the Marion Offshore Variability Ecosystem Study (MOVES II), while the 2004 and 2005 surveys formed part of the Dynamics of Eddy Impacts on Marion’s Ecosystem study (DEIMEC III and IV respectively). Macrozooplankton samples were collected using WP-2, RMT-8 and Bongo nets. Results of the hydrographic survey indicated that the region of investigation, the Polar Frontal Zone (PFZ), is an area of high mesoscale variability. During the 2004 survey the Antarctic Polar Front (APF) and the Subantarctic Front (SAF) merged to form an intense frontal feature with subsurface temperature and salinity ranging from 8.5-7.5ºC and 34.15-33.88, respectively. A cyclonic cold core eddy, believed to have been spawned from the APF, was observed during the 2005 survey. Macrozooplankton abundance and biomass ranged from 0 to 43.731 ind. m⁻³, and from 0 to 41.55 mg wwt m⁻³ respectively, during the three surveys. Among the carnivorous macrozooplankton, chaetognaths (Eukrohnia hamata and Sagitta gazellae) were most prominent, contributing up to 85% of the total biomass during all three surveys. Elevated biomass values were found near and within the frontal feature during the 2004 survey, and also along the eddy edge during the 2005 survey. However, hierarchical cluster analysis did not reveal the presence of distinct zooplankton groupings associated with the various water masses encountered during the surveys and this is probably due to the high mesoscale variability in oceanographic conditions that are characteristic of the PFZ. The total average predation impact of the selected carnivorous macrozooplankton during the 2001, 2004 and 2005 surveys accounted for 4.93 ± 6.76%, 0.55 ± 0.51% and 4.88 ± 4.45 of the mesozooplankton standing stock, respectively. S. gazellae had the highest consumption rate in all three surveys, consuming up to 800 g Dwt 1000m⁻³d⁻¹ during the study. Of the two chaetognaths, E. hamata dominated the chaetognath standing stock. The combined abundance and biomass values of E. hamata and S. gazellae ranged from 0 to 43.73 ind. m⁻³ and from 0 to 41.551 mg wwt m⁻³ respectively, during the three surveys. Inter-annual variability in the chaetognath densities was apparent. Highest abundances and biomasses tended to be associated with specific water masses, confirming the existence of a relationship between zooplankton community structure and hydrographic conditions. Generally, about 90% of the chaetognaths contained no food in their guts. S. gazellae consumed a wider variety of prey. Oil droplets occurred in the guts of ≈ 51% of E. hamata. Cannibalism was low in both species, but greater in S. gazellae than E. hamata. During the three surveys, the feeding rate values of E. hamata and S. gazellae went up to 0.48 and 2.099 prey d⁻¹ respectively. S. gazellae also had a greater predation impact on the mesozooplankton standing stock than E. hamata. The mean predation impact of the chaetognaths combined was 0.31 ± 0.291%, 0.52 ± 0.28% and 0.53 ± 0.56% of the mesozooplankton standing stock during the 2001, 2004 and 2005 surveys, respectively. During all three surveys, the majority of individuals (≈ 76%) of the chaetognaths were at stage I maturity, suggesting that during the time of study the chaetognaths were not reproducing. In both species a significant difference (log-linear analysis, p < 0.05) in maturities between the years investigated was observed. In general, there were no differences in lengths and maturities between the different water masses encountered during the surveys. The lengths of E. hamata and S. gazellae ranged from 5 to 24 mm and from 9.4 to 63.6 mm, respectively.

Note:

Antarctic tourism represents the largest and fastest growing commercial activity on the Antarctic continent. Under consideration of its unprecedented growth and diversification, the Antarctic tourism sector is viewed with increasing scrutiny and concern. This concern is expressed in discussions surrounding the success and effectiveness of the existing regulatory framework for Antarctic tourism and asks what changes might be required to adequately protect the Antarctic continent in the future. Viewpoints and interests among Antarctic tourism operators, policy-makers, researchers and other stakeholders diverge, and Antarctic tourism is discussed as being either or both benefactor and detractor to the environmental and political integrity of Antarctica. This thesis discusses, regulations drawing on regime theory, the effectiveness of Antarctic tourism. It postulates the theory that the combined regulatory efforts of Antarctic Treaty Consultative Parties (ATCPs) and industry self-regulation through the International Association of Antarctica Tour Operators (IAATO) define the Antarctic tourism regime. Using interviews and a Delphi study as the primary methods of inquiry, stakeholder viewpoints on regulatory and operational characteristics of Antarctic tourism were collected and integrated into a discussion of the effectiveness of the current regulatory regime and an assessment of potential options for regulating Antarctic tourism in the future. The interviews provide insights particularly into operational matters and the in situ practice of tour operators and their compliance with existing regulations. The Delphi study focuses on how the current regulatory issues are addressed, how rules and regulation are enacted and whether the current regulatory framework needs improvement. The thesis research shows that Antarctic tourism stakeholders are concerned about the increasing scale and diversification of Antarctic tourism and generally subscribe to a conservation imperative when assessing potential options for the future regulation of Antarctic tourism. The Antarctic Treaty System is regarded as being stable and having matured over the years, although the regime has not been tested to any great extent. Tourism development in the Antarctic may well prove to be a first test of the stability and success of the Antarctic Treaty System. Stakeholders desire a continued strong partnership between Antarctic Treaty Parties and IAATO regarding the regulation of Antarctic tourism, but conclude that in view of the rapid development of Antarctic tourism, structural, institutional and legislative changes are necessary if Antarctic tourism regulation is to remain successful. The thesis argues that these necessary changes do not inevitably involve a complete overhaul of the existing regulatory regime for Antarctic tourism and that a new overarching regulatory instrument such as a tourism convention may neither be the most desirable nor feasible approach to regulating tourism to the Antarctic. Instead, this thesis research suggests that regulatory improvements need to build on the strengths of the current regime and on a strategic vision that should guide the future regulation of Antarctic tourism.

Physical-biological interactions in the Southern Ocean were investigated using remote sensing data from several different satellite sensors. Satellite sea surface temperature data were used to study the dynamics of the Antarctic Polar Front (PF). Satellite ocean color data were used to estimate surface chlorophyll concentrations and their relation to various physical forcings within the Southern Ocean. A detailed study of phytoplankton blooms at the Antarctic Polar Front revealed that elevated chlorophyll concentrations (phytoplankton blooms) occur most often in areas where the PF interacts with large topographic features within the Southern Ocean. The physical dynamics of the PF are strongly influenced by the topography, and in turn strongly influence phytoplankton bloom dynamics. The analysis of satellite data from the modern Southern Ocean indicates that phytoplankton are limited by the availability of the micronutrient iron in most areas. This iron-limitation implies that the elevated iron inputs during glacial periods would have led to increased phytoplankton primary and export production and a stronger sink for atmospheric CO��� in the Southern Ocean. / Graduation date: 2000

Antarctic tourism represents the largest and fastest growing commercial activity on the Antarctic continent. Under consideration of its unprecedented growth and diversification, the Antarctic tourism sector is viewed with increasing scrutiny and concern. This concern is expressed in discussions surrounding the success and effectiveness of the existing regulatory framework for Antarctic tourism and asks what changes might be required to adequately protect the Antarctic continent in the future. Viewpoints and interests among Antarctic tourism operators, policy-makers, researchers and other stakeholders diverge, and Antarctic tourism is discussed as being either or both benefactor and detractor to the environmental and political integrity of Antarctica. This thesis discusses, regulations drawing on regime theory, the effectiveness of Antarctic tourism. It postulates the theory that the combined regulatory efforts of Antarctic Treaty Consultative Parties (ATCPs) and industry self-regulation through the International Association of Antarctica Tour Operators (IAATO) define the Antarctic tourism regime. Using interviews and a Delphi study as the primary methods of inquiry, stakeholder viewpoints on regulatory and operational characteristics of Antarctic tourism were collected and integrated into a discussion of the effectiveness of the current regulatory regime and an assessment of potential options for regulating Antarctic tourism in the future. The interviews provide insights particularly into operational matters and the in situ practice of tour operators and their compliance with existing regulations. The Delphi study focuses on how the current regulatory issues are addressed, how rules and regulation are enacted and whether the current regulatory framework needs improvement. The thesis research shows that Antarctic tourism stakeholders are concerned about the increasing scale and diversification of Antarctic tourism and generally subscribe to a conservation imperative when assessing potential options for the future regulation of Antarctic tourism. The Antarctic Treaty System is regarded as being stable and having matured over the years, although the regime has not been tested to any great extent. Tourism development in the Antarctic may well prove to be a first test of the stability and success of the Antarctic Treaty System. Stakeholders desire a continued strong partnership between Antarctic Treaty Parties and IAATO regarding the regulation of Antarctic tourism, but conclude that in view of the rapid development of Antarctic tourism, structural, institutional and legislative changes are necessary if Antarctic tourism regulation is to remain successful. The thesis argues that these necessary changes do not inevitably involve a complete overhaul of the existing regulatory regime for Antarctic tourism and that a new overarching regulatory instrument such as a tourism convention may neither be the most desirable nor feasible approach to regulating tourism to the Antarctic. Instead, this thesis research suggests that regulatory improvements need to build on the strengths of the current regime and on a strategic vision that should guide the future regulation of Antarctic tourism.

No description available.

No description available.

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No description available.

Thesis (Ph. D.)--Florida State University, 2003. / Advisor: Dr. Doron Nof, Florida State University, College of Arts and Sciences, Dept. of Oceanography. Title and description from dissertation home page (viewed Oct. 6, 2003). Includes bibliographical references.