A regression technique for the estimation of epiphytic invertebrate populations

SUMMARY. 1. A regression method is proposed for the estimation of populations of epiphytic invertebrates. Small samples of macrophytes and attached animals are taken by gentle enclosure. Regression analysis is used to relate the number of animals collected to the macrophyte species composition and ibiomass in these small samples. These relationships estimate the number of organisms of each taxon per unit mass of each macrophyte species. Areal population density is estimated by multiplication of macrophyte mass‐specific invertebrate density by standing macrophyte biomass. 2. The regression method yields population density estimates several times greater than the best of current methods for several fauna. Differences are most pronounced for active organisms such as water mites, amphipods, cladocerans, copepods, lepidopterans, ostracods, and trichopterans. 3. Precision levels obtained using the regression method are comparable to other techniques. The regression technique automatically provides estimates of macrophyte species‐specific colonization density and the abundance of organisms swimming among macrophytes in littoral areas.