The interactions between temperature and activity levels in driving metabolic rate: theory, with empirical validation from contrasting ectotherms

Abstract

The rate of change in resting metabolic rate (RMR) as a result of a temperature increase of 10 °C is termed the temperature coefficient (Q10), which is often used to predict how an organism's total MR will change with temperature. However, this method neglects a potentially key component of MR; changes in activity level (and thus activity MR; AMR) with temperature may significantly alter the relationship between MR and temperature. The present study seeks to describe how thermal effects on total MR estimated from RMR-temperature measurements can be misleading when the contribution of activity to total MR is neglected. A simple conceptual framework illustrates that since the relationship between activity levels and temperature can be different to the relationship between RMR and temperature, a consistent relationship between RMR and total MR cannot be assumed. Thus the thermal effect on total MR can be considerably different to the thermal effect on RMR. Simultaneously measured MR and activity from three ectotherm species with differing behavioural and physiological ecologies were used to empirically examine how changes in temperature drive changes in RMR, activity level, AMR and the Q10 of MR. These species exhibited varied activity- and MR-temperature relationships, underlining the difficulty in predicting thermal influences on activity levels and total MR. These data support a model showing that thermal effects on total MR will deviate from predictions based solely on RMR; this deviation will depend upon the difference in Q10 between AMR and RMR, and the relative contribution of AMR to total MR. To develop mechanistic, predictive models for species' metabolic responses to temperature changes, empirical information about the relationships between activity levels, MR and temperature, such as reported here, is required. This will supersede predictions based on RMR alone.

The speed and metabolic cost of digesting a blood meal depends on temperature in a major disease vector

“…Further research will be needed to determine which of these responses may be occurring in these flies. Nevertheless, the fact that these flies are capable of such flexibility in maintenance costs at a given temperature underscores some of the challenges in reporting SMR (reviewed in IUPS, 2001) and its thermal sensitivity (reviewed in Halsey et al, 2015).…”

“…Furthermore, none to our knowledge have examined SDA among different temperatures. The determination of ecological energetics across a range of temperatures may be compounded by changes in activity levels (Halsey et al, 2015) and we therefore consider changes in minimum, average and maximum metabolic rates.…”

Correlations of metabolic rate and body acceleration in three species of coastal sharks under contrasting temperature regimes

“…A Q 10 of the RMR was also calculated for blacktip sharks, as they do not exhibit a SMR. This RMR Q 10 was calculated using only RMR data from the two temperature groupings that overlapped in ODBA levels to ensure that the comparison was made between metabolic rates from similar activity levels, as volitional activity tends to increase with temperature (Halsey et al, 2015). All Q 10 values were calculated according to the Van't Hoff equation (Eqn 2):…”

LAJU RESPIRASI INDUK IKAN BLACKHEAD SEABREAM Acanthopagrus schlegelii PADA SUHU PEMELIHARAAN YANG BERBEDA

“…Dari perspektif tingkah laku, misalnya pada suhu di mana kemungkinannya tinggi untuk mendapatkan makanan, hewan dapat meningkatkan tingkat aktivitas mereka untuk memaksimalkan asupan energi (Speakman, 1986) atau alternatif lainnya mereka mungkin menjadi kurang aktif, misalnya karena banyak terdapat predator (Anholt et al, 2000;Werner & Anholt, 1993). Sedangkan dari perspektif fisiologis, ada efek langsung dari suhu pada reaksi biokimia yang terlibat dalam gerak (Halsey et al, 2015).…”