2 results
A top–down, multidisciplinary study of the structure and function of the pack-ice ecosystem in the eastern Ross Sea, Antarctica
- S.F. Ackley, J.L. Bengtson, P. Boveng, M. Castellini, K.L. Daly, S. Jacobs, G.L. Kooyman, J. Laake, L. Quetin, R. Ross, D.B. Siniff, B.S. Stewart, I. Stirling, J. Torres, P.K. Yochem
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- Journal:
- Polar Record / Volume 39 / Issue 3 / July 2003
- Published online by Cambridge University Press:
- 26 June 2003, pp. 219-230
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- Article
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We used a top–down, multidisciplinary approach to examine the physical and biological environment of the pack ice of the eastern Ross Sea (approximately 125–170°W) during the austral summer of 1999/2000 from RVIB Nathaniel B. Palmer and its ship-based helicopters. The approach focused on pack-ice seals while incorporating studies of biotic and abiotic factors that may influence the distribution and abundances of these apex predators in the Ross Sea to yield a holistic understanding of the structure and function of this complex, large marine ecosystem. This research represented the US component of the international Antarctic Pack Ice Seal (APIS) program, which was designed to document the circumpolar distribution and abundance of Antarctic pack-ice seals. The eastern Ross Sea is one of the two major areas in the Southern Ocean where substantial pack ice exists throughout summer. We found that vast multi-year ice floes (>20 km diameter) and smaller floes north of the shore-fast ice front provide a unique habitat for seals and penguins (apex predators) to forage and haul out while molting in late summer. Farther north, more Ross seals were observed than in any previous surveys in the circumpolar pack ice, perhaps because they are attracted to the area in summer to molt on large stable first-year ice floes. Extensive fast ice along the coastline and drifting pack ice in the shelf–slope boundary zone provided haul-out areas for seals and penguins with access to feeding in the coastal shelf region. Distributions of potential prey for seals and penguins varied over the study area, as determined by nets, acoustics, and diving surveys. Antarctic krill (Euphausia superba) were found throughout the survey region, overlapping the distributions of two smaller species, Thysanoëssa macrura (primarily off-shelf) and E. crystallorophias (primarily found on-shelf). In some locations, E. superba occurred at high densities underneath ice floes, where they foraged on the sea-ice microbial community. Two general fish communities, oceanic and shelf, were distinguished. Off-shelf fishes were members of the classic oceanic midwater fish fauna, whereas on-shelf fishes were Antarctic endemics. The abundance of pelagic fishes was relatively low throughout the study area compared with other Southern Ocean ecosystems. In contrast, benthic fish biomass and diversity on-shelf were high (41 species, 6 families). Hydroacoustic analyses indicated that densities of potential prey were highest in the coastal shelf region where large aggregations of euphausiids (primarily E. crystallorophias) and individual juvenile Antarctic silverfish (Pleuragramma antarcticum) occurred.
5 - Telemetry and electronic technology
- Edited by R. M. Laws, St Edmund's College, Cambridge
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- Book:
- Antarctic Seals
- Published online:
- 05 February 2010
- Print publication:
- 07 October 1993, pp 119-139
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Summary
Introduction
Rapid advances in the field of electronics over the past several years have made powerful research tools available to pinniped investigators. In particular, the remarkable miniaturization of solid-state circuitry through semiconductor technology has made it feasible to deploy highly sophisticated instruments on free-ranging individuals. These instruments have become important assets in the study of pinniped behaviour, ecology and physiology.
This chapter briefly outlines some of the types of instruments that have relevance to studies of free-ranging Antarctic seals. No attempt has been made to include a description of instruments and devices principally used in captive or laboratory studies. The main categories of instruments described are radio tracking and telemetry, sonic devices, archival recorders (behavioural, ecological and physiological) and satellite-linked hardware. A section on attachment methods is also included. A list of the addresses of research groups or manufacturers is provided in Appendix 5.1, at the end of this chapter.
Radio tracking and telemetry
Radio transmitters have been utilized in wildlife studies since the early 1960s (Cochran & Lord, 1963), and have assisted research on Antarctic pinnipeds since 1968 (Siniff, Tester & Kuechle, 1969, 1971). Transmitters can be monitored for two basic types of information: (1) the presence or absence of a signal (e.g. haul-out patterns, location) and (2) the relay of various types of data (e.g. heart rate, ambient temperature). Most studies using radio transmitters attached to Antarctic seals have involved monitoring activity patterns and movements of individuals (e.g. Siniff J.L. Bengtson et al., 1975). In addition to the brief description given below, several other sources offer a helpful introduction to using radio transmitters in wildlife studies (Cochran, 1980; Amlaner & Macdonald, 1980;Cheeseman & Mitson, 1982; Kenward, 1987).