Oxygen consumption of active and inactive adult tiger beetles

ABSTRACT. Oxygen consumption (O₂) in six species of adult tiger beetles Cicindela spp. (Coleoptera: Cicindelidae) was correlated with body mass and temperature during rest. In beetles forced to run and/or right themselves continuously for 5–10 min at 25°C, O₂ was approximately 7–12 times as high as in resting individuals; the difference increased with increasing mass. Resting and active VO₂ were similar to previous results for other beetles, although the slope of log O₂ on log mass was lower. Detailed analysis suggests the existence of taxonomic and ecological correlates of resting metabolism. The possible ecological implications and adaptive advantages of these results for adult tiger beetles are discussed.     

Variation in chemical composition of the River Frome, England, from 1965 to 1972

This study covers a 7-year period from 1965 to 1972, and shows the variation in flow, water chemistry and throughput of nutrients. The annual discharge of the River Frome varied considerably from year to year, ranging from a mean value of 4.48 m³ sec⁻¹ in 1971 to one of 8.38 m³ sec⁻¹ in 1966. The mean annual nutrient losses calculated over all 7 years of study from the River Frome catchment were: Nitrate 11.4 kg ha⁻¹, phosphorus 0.49 kg ha⁻¹ and potassium 8.4 kg ha⁻¹. There has been an increase in annual throughput (in years of similar flow) of 21% in phosphate and 41% in nitrate from 1965 to 1972.     

The seasonal variation in silicon concentration in chalk-streams in relation to diatom growth

SUMMARY. Changes in silicon concentration were used to investigate the seasonal cycle of diatoms in chalk-streams. Bore-hole water shows no significant variation in silicon concentration. Five kilometres downstream there is a significant reduction between March and May. Further downstream the cumulative effect of biological silicon removal shows more complex patterns. There is a considerable variation in the seasonal pattern from year to year but an analysis of the seasonal pattern averaged over thirteen years on the River Frome confirms a later summer silicon reduction in August-September, in addition to a much larger reduction in the spring.
The negative correlation between suspended chlorophyll-α and silicon concentrations confirms that suspended chlorophyll-α concentrations respond more closely to changes in the loosely attached diatom flora than to other sources of chlorophyll-α. However, neither variable is always suitable for monitoring changes in benthic diatoms. In headwaters, for example, transitory changes in diatoms do not have a significant impact on silicon concentration, while further downstream the suspended solids are affected by many other factors.
Estimates of diatom production, based on changes in silicon concentration, gave rates of 1–2 g Si m_-2 day_-1 in a small headwater chalkstream during the spring.