Climate warming drives a temperate-zone lizard to its upper thermal limits, restricting activity, and increasing energetic costs.

Lizards are considered vulnerable to climate change because many operate near their thermal maxima. Exposure to higher temperatures could reduce activity of these animals by forcing them to shelter in thermal refugia for prolonged periods to avoid exceeding lethal limits. While rising temperatures should reduce activity in tropical species, the situation is less clear for temperate-zone species where activity can be constrained by both low and high temperatures.

Prey availability affects daily torpor by free-ranging Australian owlet-nightjars (Aegotheles cristatus).

Food availability, ambient temperatures (T(a)), and prevailing weather conditions have long been presumed to influence torpor use. To a large extent, this is based on measurements in the laboratory of animals placed on restricted diets and kept at low T (a). Information on the determinants of torpor employment in the field is limited.

Roost type influences torpor use by Australian owlet-nightjars.

Australian owlet-nightjars (Aegotheles cristatus; ∼50 g) are one of only a few avian species that roost in cavities year-round and regularly enter torpor. Cavity roosts act as thermal buffers, and roost type likely affects energy expenditure of small birds. We used radiotelemetry to locate diurnal winter roost sites of owlet-nightjars in central Australia and to measure body (T (b)) and skin (T (skin)) temperature.

Seasonal variation in thermal energetics of the Australian owlet-nightjar (Aegotheles cristatus).

Many birds living in regions with seasonal fluctuations in ambient temperatures (T(a)) typically respond to cold by increasing insulation and adjusting metabolic rate. Seasonal variation in thermal physiology has not been studied for the Caprimulgiformes, an order of birds that generally have basal metabolic rates (BMR) lower than predicted for their body mass. We measured the metabolic rate and thermal conductance of Australian owlet-nightjars (Aegotheles cristatus) during summer and winter using open-flow respirometry.

A micro-dilution method for detecting oxytetracycline-resistant bacteria in marine sediments from salmon and mussel aquaculture sites and an urbanized harbour in Atlantic Canada.

A micro-dilution technique with changes in optical density (OD) used to measure bacterial growth over 72 h in culture media containing 0, 5, 10, 20, 40, 80 and 160 microg OTC (oxytetracycline)ml(-1) was applied to determine growth inhibition (GI) in mixed bacterial strains cultured from samples of marine sediments and salmon feed pellets. Growth of control cultures (Aeromonas salmonicida) was inhibited at all OTC concentrations. Some feed pellet samples and under-cage sediments from salmon aquaculture sites in the Bay of Fundy showed GI up to > or = 160 microg OTCml(-1).