Seasonal changes in the diving performance of the bimodally respiring freshwater turtle Rheodytes leukops in a natural setting

2003 ◽  
Vol 81 (4) ◽  
pp. 617-625 ◽  
Author(s):  
Matthew A Gordos ◽  
Craig E Franklin ◽  
Colin J Limpus
Keyword(s):  
Metabolic Acidosis ◽  
Environmental Conditions ◽  
Seasonal Changes ◽  
Physiological State ◽  
Metabolic Cost ◽  
Freshwater Turtle ◽  
Natural Setting ◽  
Aquatic Respiration ◽  
Pressure Sensitive ◽  
Austral Autumn

The objective of this study was to investigate how seasonally fluctuating environmental conditions influence the diving performance of the highly aquatic, bimodally respiring turtle Rheodytes leukops in a natural setting. Over four consecutive seasons (Austral autumn 2000 to summer 2001), the diving behaviour of adult turtles was recorded via pressure-sensitive time–depth recorders within Marlborough Creek, central Queensland, Australia. Short surfacing intervals recorded for R. leukops in winter suggest that the species utilizes aquatic respiration as an overwintering strategy to prevent the development of a metabolic acidosis during the long inactive dives observed during the season. As water temperature increases and aquatic PO2 decreases, R. leukops switches from facultative to obligate air-breathing, presumably because of the increased metabolic cost associated with aquatic respiration under summer conditions. Increases in mean surfacing time from winter to spring and summer are attributed to seasonal changes in behaviour possibly associated with foraging rather than to the physiological state of the turtle, given that no difference in median surfacing time among seasons was observed.

Seasonal changes in the diel surfacing behaviour of the bimodally respiring turtle Rheodytes leukops

2003 ◽  
Vol 81 (9) ◽  
pp. 1614-1622 ◽  
Author(s):  
Matthew A Gordos ◽  
Craig E Franklin ◽  
Colin J Limpus
Keyword(s):  
Water Temperature ◽  
Seasonal Changes ◽  
Abiotic Factors ◽  
Diurnal Variations ◽  
Freshwater Turtle ◽  
Behavioural State ◽  
Pressure Sensitive ◽  
Diel Fluctuations ◽  
Increased Activity ◽  
Austral Autumn

The purpose of this study was to determine whether a relationship existed between the diel surfacing trends of the bimodally respiring freshwater turtle Rheodytes leukops and daily fluctuations in specific biotic and abiotic factors. The diel surfacing behaviour of adult R. leukops was recorded over four consecutive seasons (Austral autumn 2000 – summer 2001) within Marlborough Creek, central Queensland, Australia, using pressure-sensitive time–depth recorders. Additionally, diurnal variations in water temperature and aquatic PO2 level, as well as the turtle's behavioural state (i.e., active versus resting), were monitored. In autumn and summer, surfacing frequency increased significantly during the daylight hours, with peak levels normally occurring around dawn (0500–0700) and dusk (1700–1900). However, no consistent diel surfacing trend was recorded for the turtles in winter or spring, owing to considerable variation among individual R. leukops. Diurnal surfacing trends recorded for R. leukops in autumn and summer are attributed to periods of increased activity (possibly associated with foraging) during the daylight hours and not to daily variations in water temperature or aquatic PO2 level. Turtles generally remained at a depth greater than 1 m throughout the day, where the effect of diel fluctuations in water temperature (<0.5 °C) and aquatic PO2 level (<15 mm Hg (1 mm Hg = 133.322 Pa)) was considered to be negligible.

Maintaining the Camps

2018 ◽  
Author(s):  
Connie Y. Chiang
Keyword(s):  
Environmental Conditions ◽  
Seasonal Changes ◽  
Natural World ◽  
Japanese American ◽  
Alkaline Soil ◽  
Water Pipelines ◽  
American Labor

This chapter focuses on the maintenance of the camps. It explores how wartime shortages and Japanese American labor protests intersected with harsh environmental conditions, complicating the WRA’s efforts to keep the camps running smoothly. One of the first challenges was finding adequate coal to heat the camps during the winter. The WRA then confronted the protests of detainees, who called attention to how seasonal changes added to their labor duties. Alkaline soil, moreover, ate away at water pipelines and required constant repairs. The natural world helped to shape modes of Japanese American resistance, as some individuals refused to work or went on strike.

scholarly journals Photoperiodic regulation of prolactin secretion: changes in intra-pituitary signalling and lactotroph heterogeneity

2004 ◽  
Vol 180 (3) ◽  
pp. 351-356 ◽  
Author(s):  
JD Johnston
Keyword(s):  
Environmental Conditions ◽  
Seasonal Changes ◽  
Mammalian Species ◽  
Prolactin Secretion ◽  
Day Length ◽  
Pars Tuberalis ◽  
Photoperiodic Regulation ◽  
Pituitary Lactotroph

Many mammalian species utilise day-length (photoperiod) to adapt their physiology to seasonal changes in environmental conditions, via secretion of pineal melatonin. Photoperiodic regulation of prolactin secretion is believed to occur via melatonin-mediated changes in the secretion of a putative prolactin secretagogue, tuberalin, from the pituitary pars tuberalis. Despite the in vivo and in vitro evidence in support of this intra-pituitary signalling mechanism, the identity of tuberalin has yet to be elucidated. This paper reviews recent advances in the characterisation of tuberalin and the regulation of its secretion. Furthermore, the hypothesis that pituitary lactotroph cells display heterogeneity in their response to changing photoperiod and tuberalin secretion is examined.

Studies of the hydrobiology of a tropical lake in north-western Queensland. II. Seasonal changes in thermal and dissolved oxygen characteristics

1980 ◽  
Vol 31 (5) ◽  
pp. 589 ◽  
Author(s):  
CM Finlayson ◽  
TP Farrell ◽  
DJ Griffiths
Keyword(s):  
Dissolved Oxygen ◽  
Water Column ◽  
Environmental Conditions ◽  
Seasonal Changes ◽  
Thermal Stratification ◽  
Oxygen Depletion ◽  
Tropical Lake ◽  
North Western

The stratification characteristics of Lake Moondarra (24�34'S.,139�35'E.), a man-made lake in north- western Queensland, have been studied. Evidence is presented that the lake approximates the warm polymictic type in which no persistent thermal stratification ever develops. During the cooler months, thermal stratification breaks down during the night; in the warmer months, the intense rainstorms prevent the establishment of a persistently stratified water column. The shallowness of the lake relative to its surface areaand the prevailing environmental conditions ensure that extensive periods of oxygen depletion do not develop in the water column. It is concluded that a strong and prolonged period of thermal stratification, with subsequent serious effects of the availability of dissolved oxygen in the deeper layers, would only arise if, in a particular year. there were no significant rainstorms.

Variation in calcification rate of Acropora downingi relative to seasonal changes in environmental conditions in the northeastern Persian Gulf

Coral Reefs ◽  
2016 ◽  
Vol 35 (4) ◽  
pp. 1371-1382 ◽  
Author(s):  
Jahangir Vajed Samiei ◽  
Abolfazl Saleh ◽  
Arash Shirvani ◽  
Neda Sheijooni Fumani ◽  
Mehri Hashtroudi ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Persian Gulf ◽  
Seasonal Changes ◽  
Calcification Rate
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