THE USE OF THE SIZE STRUCTURE OF BENTHIC MACROFAUNAL COMMUNITIES TO ESTIMATE FAUNAL BIOMASS AND SECONDARY PRODUCTION

A general allometric equation (P = 0.0049 * B0.80T0.89) which relates daily macrobenthic production P (μg· day-1) to ash-free dry weight B (μg) and water temperature T (°C) was calculated from the published production rates of 41 invertebrate species. Allometric equations were also calculated from the same literature set for adult (P = 0.0050 * B0.78T0.92) and juvenile (P = 0.0049 * B0.86 T0.80) animals. The biomass exponent of the general equation (0.80) differed significantly from 0.63, the value predicted by Banse & Mosher's (1980) equation P B = 0.65Ms-0.37. A new method of estimating the secondary production of benthic macrofaunal communities based on the use of these equations is outlined. The method requires relatively little sampling effort and is applicable to marine and estuarine species living in water temperatures of 5-30°C. Production is calculated using the mean ash-free dry weight of animals retained by sieves of differing mesh size, the abundances of animals in different sieve size classes, and the general equations described above. The mean biomass of animals in the various sieve size classes used in production calculations can be measured directly, or, providing that the faunal assemblage does not contain many long flexible individuals or is dominated by a few very large animals, using the empirically derived equation log B = - 1.01 + 2.64 *log S, where B is faunal ash-free dry weight (mg) and S is sieve size (mm). © 1990.