... A. Kato (N gl)- Y. Naito National Insitute of Polar Research. 1-9-10 Kaga, Itabashi-ku, Tokyo... more ... A. Kato (N gl)- Y. Naito National Insitute of Polar Research. 1-9-10 Kaga, Itabashi-ku, Tokyo 173, Japan; Fax: + ~I1-3-3962-5743; E-mail: akato@nipr.ac.jp I. Nishiumi Department of Biology, Faculty of Science, Osaka City University, Sugimoto, Sumiyossi-ku, Osaka 558, Japan ...
Metamorphosis is a widespread developmental process that involves considerable changes in morphol... more Metamorphosis is a widespread developmental process that involves considerable changes in morphology, habitat use, ecology and behaviour between early developmental (larval) stages and adult forms. Among amphibians, anuran larvae (tadpoles) undergo massive morphological and ecological changes during their development, with early stages characterized by somatic growth, whereas more conspicuous changes (i.e. metamorphosis) occur later during development. In this study, we examined how locomotor and behavioural traits covary with morphology (body size) and metamorphosis (hindlimb and forelimb development) across developmental stages in spined toad (Bufo spinosus) tadpoles. As expected, we found that locomotion and behaviour undergo significant changes during tadpole development. These changes are curvilinear across developmental stages, with a phase of increasing activity and locomotion followed by a phase of stasis and/or reduction in locomotion and behavioural complexity. All the met...
important component of the Antarctic marine ecosys-tem, is closely associated with sea ice. Using... more important component of the Antarctic marine ecosys-tem, is closely associated with sea ice. Using data col-lected by Japanese Antarctic Research Expeditions since the 1960s, we examined trends in breeding populations of this species around Lützow-Holm Bay. Ten colonies ranging in size from 10 to 2,500 individuals were counted along the Soya Coast. Populations fluctuated synchronously, and overall increased at most colonies, except for two: one located deep inside the bay and another where human disturbance was substantial. Populations tended to increase during, or after, periods of sparse sea ice in summer, a condition that occurred once every decade. An increase in population size also occurred 5 years after a winter of extensive sea ice and after a winter of especially reduced sea ice.
The trends of penguin populations are thought to be reliable indicators of ecosystem changes in t... more The trends of penguin populations are thought to be reliable indicators of ecosystem changes in the Southern Ocean. There are seven Adelie penguin colonies and one emperor penguin colony along the Prince Olav Coast and one emperor penguin colony on the Riiser-Larsen Peninsula. We compiled and analyzed the available data collected by airborne and ground census between +31+ and ,*** in order to determine the breeding status of penguins in this area. Adelie penguin populations increased at two colonies; no apparent trends were observed at other colonies. Emperor penguin populations were high in the mid-+33*s and suddenly decreased in ,***. Populations need to be carefully monitored in the coming years. key words: Adelie penguin, emperor penguin, population, East Antarctica
Marine predators are ecosystem sentinels because their foraging behaviour and reproductive succes... more Marine predators are ecosystem sentinels because their foraging behaviour and reproductive success reflect the variability occurring in the lower trophic levels of the ecosystem. In an era of environmental change, monitoring top predators species can provide valuable insights into the zones of ecological importance that need to be protected. In this context, we monitored the Adélie penguin (Pygoscelis adeliae) as a bio-indicator near Dumont d'Urville, an area of the East Antarctic sector currently being considered for the establishment of a Marine Protected Area (MPA), using GPS-based tracking tags during the 2012/13 austral summer breeding season. The habitat use and foraging areas of the penguins differed by breeding stage and sex and were strongly associated with patterns in bathymetry and sea-ice distribution. The first trips, undertaken during the incubation phase, were longer than those during the guard phase and were associated with the northern limit of the sea-ice exten...
The diving pattems of two male and one female Blue-eyed Cormorants Phalacrocorax atriceps were re... more The diving pattems of two male and one female Blue-eyed Cormorants Phalacrocorax atriceps were recorded with continuous-recording time-depth recorders for l0-13 days during the 1990 breeding season. For the female only data on time and depth were retrieved: diving was distributed through the day (including 3lVo at nighQ; mean dive depth was 63 m. Males dived mainly in the afternoon and evening. Their mean dive clepths were 61.4 and 83.9 m; mean dive durations 3.4 and 4.6 min; t ime at maximum depth (bottom time) averaged 28 and 41 % of time submerged; descent time (0.4 and 0.5 min) was shorter than ascent time (1.6 ancl 2.9 min); dive/pause ratios were 0.4 and 0.5 and surface interval was not increased with preceding dive duration. The incubating male making one long dive bout per day, made fewer, longer dives, with less overall bottom time, than thc chick-rearing male, which made at least two bouts per day. Most characteristics of diving in 1990 (a year of avcragc breeding success) were similar to data from 1989 (a year of breeding failure). However, there were morc, shorter dive bouts in 1989 and shallow (travelling) dives were more frequent: both consistent with lower prey availabil ity in 1989 necessitating frequent changes of foraging sites.
SUMMARY Loggers were attached to free-ranging Brünnich's guillemots Uria lomvia during dives... more SUMMARY Loggers were attached to free-ranging Brünnich's guillemots Uria lomvia during dives, to measure swim speeds, body angles, stroke rates,stroke and glide durations, and acceleration patterns within strokes, and the data were used to model the mechanical costs of propelling the body fuselage(head and trunk excluding wings). During vertical dives to 102–135 m,guillemots regulated their speed during descent and much of ascent to about 1.6±0.2 m s–1. Stroke rate declined very gradually with depth, with little or no gliding between strokes. Entire strokes from 2 m to 20 m depth had similar forward thrust on upstroke vs downstroke,whereas at deeper depths and during horizontal swimming there was much greater thrust on the downstroke. Despite this distinct transition, these differences had small effect (<6%) on our estimates of mechanical cost to propel the body fuselage, which did not include drag of the wings. Work stroke–1 was quite high as speed increased dramatically in...
... A. Kato (N gl)- Y. Naito National Insitute of Polar Research. 1-9-10 Kaga, Itabashi-ku, Tokyo... more ... A. Kato (N gl)- Y. Naito National Insitute of Polar Research. 1-9-10 Kaga, Itabashi-ku, Tokyo 173, Japan; Fax: + ~I1-3-3962-5743; E-mail: akato@nipr.ac.jp I. Nishiumi Department of Biology, Faculty of Science, Osaka City University, Sugimoto, Sumiyossi-ku, Osaka 558, Japan ...
Metamorphosis is a widespread developmental process that involves considerable changes in morphol... more Metamorphosis is a widespread developmental process that involves considerable changes in morphology, habitat use, ecology and behaviour between early developmental (larval) stages and adult forms. Among amphibians, anuran larvae (tadpoles) undergo massive morphological and ecological changes during their development, with early stages characterized by somatic growth, whereas more conspicuous changes (i.e. metamorphosis) occur later during development. In this study, we examined how locomotor and behavioural traits covary with morphology (body size) and metamorphosis (hindlimb and forelimb development) across developmental stages in spined toad (Bufo spinosus) tadpoles. As expected, we found that locomotion and behaviour undergo significant changes during tadpole development. These changes are curvilinear across developmental stages, with a phase of increasing activity and locomotion followed by a phase of stasis and/or reduction in locomotion and behavioural complexity. All the met...
important component of the Antarctic marine ecosys-tem, is closely associated with sea ice. Using... more important component of the Antarctic marine ecosys-tem, is closely associated with sea ice. Using data col-lected by Japanese Antarctic Research Expeditions since the 1960s, we examined trends in breeding populations of this species around Lützow-Holm Bay. Ten colonies ranging in size from 10 to 2,500 individuals were counted along the Soya Coast. Populations fluctuated synchronously, and overall increased at most colonies, except for two: one located deep inside the bay and another where human disturbance was substantial. Populations tended to increase during, or after, periods of sparse sea ice in summer, a condition that occurred once every decade. An increase in population size also occurred 5 years after a winter of extensive sea ice and after a winter of especially reduced sea ice.
The trends of penguin populations are thought to be reliable indicators of ecosystem changes in t... more The trends of penguin populations are thought to be reliable indicators of ecosystem changes in the Southern Ocean. There are seven Adelie penguin colonies and one emperor penguin colony along the Prince Olav Coast and one emperor penguin colony on the Riiser-Larsen Peninsula. We compiled and analyzed the available data collected by airborne and ground census between +31+ and ,*** in order to determine the breeding status of penguins in this area. Adelie penguin populations increased at two colonies; no apparent trends were observed at other colonies. Emperor penguin populations were high in the mid-+33*s and suddenly decreased in ,***. Populations need to be carefully monitored in the coming years. key words: Adelie penguin, emperor penguin, population, East Antarctica
Marine predators are ecosystem sentinels because their foraging behaviour and reproductive succes... more Marine predators are ecosystem sentinels because their foraging behaviour and reproductive success reflect the variability occurring in the lower trophic levels of the ecosystem. In an era of environmental change, monitoring top predators species can provide valuable insights into the zones of ecological importance that need to be protected. In this context, we monitored the Adélie penguin (Pygoscelis adeliae) as a bio-indicator near Dumont d'Urville, an area of the East Antarctic sector currently being considered for the establishment of a Marine Protected Area (MPA), using GPS-based tracking tags during the 2012/13 austral summer breeding season. The habitat use and foraging areas of the penguins differed by breeding stage and sex and were strongly associated with patterns in bathymetry and sea-ice distribution. The first trips, undertaken during the incubation phase, were longer than those during the guard phase and were associated with the northern limit of the sea-ice exten...
The diving pattems of two male and one female Blue-eyed Cormorants Phalacrocorax atriceps were re... more The diving pattems of two male and one female Blue-eyed Cormorants Phalacrocorax atriceps were recorded with continuous-recording time-depth recorders for l0-13 days during the 1990 breeding season. For the female only data on time and depth were retrieved: diving was distributed through the day (including 3lVo at nighQ; mean dive depth was 63 m. Males dived mainly in the afternoon and evening. Their mean dive clepths were 61.4 and 83.9 m; mean dive durations 3.4 and 4.6 min; t ime at maximum depth (bottom time) averaged 28 and 41 % of time submerged; descent time (0.4 and 0.5 min) was shorter than ascent time (1.6 ancl 2.9 min); dive/pause ratios were 0.4 and 0.5 and surface interval was not increased with preceding dive duration. The incubating male making one long dive bout per day, made fewer, longer dives, with less overall bottom time, than thc chick-rearing male, which made at least two bouts per day. Most characteristics of diving in 1990 (a year of avcragc breeding success) were similar to data from 1989 (a year of breeding failure). However, there were morc, shorter dive bouts in 1989 and shallow (travelling) dives were more frequent: both consistent with lower prey availabil ity in 1989 necessitating frequent changes of foraging sites.
SUMMARY Loggers were attached to free-ranging Brünnich's guillemots Uria lomvia during dives... more SUMMARY Loggers were attached to free-ranging Brünnich's guillemots Uria lomvia during dives, to measure swim speeds, body angles, stroke rates,stroke and glide durations, and acceleration patterns within strokes, and the data were used to model the mechanical costs of propelling the body fuselage(head and trunk excluding wings). During vertical dives to 102–135 m,guillemots regulated their speed during descent and much of ascent to about 1.6±0.2 m s–1. Stroke rate declined very gradually with depth, with little or no gliding between strokes. Entire strokes from 2 m to 20 m depth had similar forward thrust on upstroke vs downstroke,whereas at deeper depths and during horizontal swimming there was much greater thrust on the downstroke. Despite this distinct transition, these differences had small effect (<6%) on our estimates of mechanical cost to propel the body fuselage, which did not include drag of the wings. Work stroke–1 was quite high as speed increased dramatically in...
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