
%0 Journal Article
%A Marchant, R. 
%A Hehir, G. 
%T How efficient is extraction of stream insect larvae from quantitative benthic samples?
%J Marine and Freshwater Research
%D 2000/10/30
%V 51
%N 8
%P 825-826
%K glossosomatids
%R https://doi.org/10.1071/MF00072
%U https://www.publish.csiro.au/paper/MF00072 
%X The efficiency of extraction of Agapetus larvae (Glossosomatidae : Trichoptera) from quantitative benthic samples was estimated by the use of two approaches: an indirect estimate based on the probability of missing a specimen in two scans of a sample (the two-count method) and a direct estimate derived by re-picking samples. Both approaches gave similar estimates for the probability of missing a specimen of a given size and both showed that this probability increased as size decreased; losses ranged from 6% to 30%. The two-count method thus provides a reliable way to compensate for these losses. Such corrections made little difference to conclusions concerning Agapetus population density, larval growth or secondary production derived from a previous study. However, when no corrections are applied, mortality estimates may be inaccurate if early instars are picked with less efficiency than later ones. 
