Comparative productivity in ecosystems—secondary productivity

The role of zoobenthos in energy flow in two shallow lakes

“…The parameters influencing NPE most were temperature and population biomass during periods with high water temperature. NPE values of 0.41 to 0.48 is within the range found for invertebrates (McNeil & Lawton, 1970;Heal & MacLean, 1975;Alimov, 1991), but as an average for the total community the value for Myvatn seems high. Humphreys (1979) suggested a NPE of 0.3-0.4 for invertebrates.…”

“…Published values of assimilation efficiency (A/I = assimilation/ingestion) vary greatly (e.g. Welch, 1968;Heal & MacLean, 1975;Berrie, 1976;Schroeder, 1981). Therefore, to estimate the ingestion, an assimilation efficiency of 50% for herbivores, 20% for detritivores, and 60% for carnivores was assumed as did Strayer & Likens (1986) in their computation of an energy budget for the zoobenthos of Mirror Lake.…”

Effect of Sludge Addition on Biological Properties of Soil under Rice Cultivation

“…Microbial activity is a good measure of organic matter turnover in soil since generally more than 90% of energy flow through microbial decomposer (Heal and MacLean, 1975). Hence activity of acid phosphatase, alkaline phosphatase and fluorescein diacetate in soil was studied in sludge amended soil.…”

Theoretical estimates of consumable food and probability of acquiring food in larvae of Chrysomya putoria (Diptera: Calliphoridae)

“…However, Ullyett makes an assumption of a theoretically value of 100% of food conversion into biomass, which is very unrealistic. In the present study, we utilize an ECI of 39%, considered by Heal (1974) as a mean value for saprophagous invertebrates. For insects, such as blowflies, whose larvae experience competition for food, the maximum weight will, to a large extent, depend on the degree of larval crowding, which is known to impose constraints both in the number and weight of survivors.…”

“…This approach combines estimates of densityindependent larval mortality (Morris 1990) to infer the amount of food consumable according to Ullyett (1950), using pupal weight and survival data. The key calculations are based on a theoretical mean value of efficiency of conversion of ingested food (ECI) obtained in saprophagous invertebrates by Heal (1974) (see review in Slansky & Scriber 1982). The probability of acquiring food per unit of time, the time in discrete units necessary for the larvae to attain the minimal pupal weight, and the time taken to exhaust the food supply were also calculated (de Jong 1976), because of their importance for organisms that compete for limited amounts of food such as the majority of larvae of calliphorid flies.…”