Ventilation rate and behavioural responses of two species of intertidal goby (Pisces : Gobiidae) at extremes of environmental temperature

We investigated the behavioural responses of two gobiid fish species to temperature to determine if differences in behaviour and ventilation rate might explain any apparent vertical zonation. A survey of the shore at Manly, Moreton Bay revealed Favonigobius exquisitus to dominate the lower shore and Pseudogobius sp. 4 the upper shore. These species were exposed to a range of temperatures (15-40 degreesC) in aquaria for up to 6 h. At 20 degreesC F. exquisitus exhibited a mean gill ventilation rate of 26 +/- 1.4 bpm (beats per minute) differing significantly from Pseudogobius, which ventilated at a fivefold greater rate of 143 +/- 6 bpm. The ventilation rate in F. exquisitus underwent a fivefold increase from normal local water temperature (20 degreesC) to high temperature (35 degreesC) conditions, whereas that of Pseudogobius did not even double, suggesting that Pseudogobius sp. is a better thermal regulator than F. exquisitus. While both species emerged from the water at high temperatures (>30 degreesC) the behaviours they exhibited while immersed at high temperature were quite different. F. exquisitus undertook vertical displacement movements we interpret as an avoidance response, whereas Pseudogobius sp. appeared to use a coping strategy involving movements that might renew the water mass adjacent to its body. The thermal tolerances and behaviours of F. exquisitus and Pseudogobius sp. are in broad agreement with their vertical distribution on the shore.

Understanding environmental influences on walking - Review and research agenda

Background: Understanding how environmental attributes can influence particular physical activity behaviors is a public health research priority. Walking is the most common physical activity behavior of adults; environmental innovations may be able to influence rates of participation. Method: Review of studies on relationships of objectively assessed and perceived environmental attributes with walking. Associations with environmental attributes were examined separately for exercise and recreational walking, walking to get to and from places, and total walking. Results: Eighteen Studies were identified. Aesthetic attributes, convenience of facilities for walking (sidewalks, trails); accessibility of destinations (stores, park, beach); and perceptions about traffic and busy roads were found to be associated with walking for particular purposes. Attributes associated with walking for exercise were different front those associated with walking to get to and from places. Conclusions: While few studies have examined specific environment-walking relationships, early evidence is promising. Key elements of the research agenda are developing reliable and valid measures of environmental attributes and walking behaviors, determining whether environment-behavior relationships are causal, and developing theoretical models that account for environmental influences and their interactions with other determinants. (C) 2004 American Journal of Preventive Medicine.

Physiological mechanisms of thermoregulation in reptiles: a review

The thermal dependence of biochemical reaction rates means that many animals regulate their body temperature so that fluctuations in body temperature are small compared to environmental temperature fluctuations. Thermoregulation is a complex process that involves sensing of the environment, and subsequent processing of the environmental information. We suggest that the physiological mechanisms that facilitate thermoregulation transcend phylogenetic boundaries. Reptiles are primarily used as model organisms for ecological and evolutionary research and, unlike in mammals, the physiological basis of many aspects in thermoregulation remains obscure. Here, we review recent research on regulation of body temperature, thermoreception, body temperature set-points, and cardiovascular control of heating and cooling in reptiles. The aim of this review is to place physiological thermoregulation of reptiles in a wider phylogenetic context. Future research on reptilian thermoregulation should focus on the pathways that connect peripheral sensing to central processing which will ultimately lead to the thermoregulatory response.