Benthic Faunas of Forested Streams and Suggestions for Their Management

The influence of physical factors and forest type on the distribution of benthic invertebrates in 43 New Zealand streams was investigated using a systematic survey technique. A small nucleus of common taxa was numerically dominant at most sites regardless of forest type. The mayfly, Deleatidium was found at 42 of the sites and was the most abundant taxon at 27. Other widely distributed genera were Nesameletus, Coloburiscus (Ephemeroptera), Stenoperla, Zelandoperla, Zelandobius (Plecoptera), Olinga and Hydrobiosis (Trichoptera). Numbers of invertebrate taxa and relative abundance of shredders (large particle detritivores) were not correlated with stream gradient but were correlated significantly with stream stability. Implications of these findings for stream management are discussed, and it is suggested that combined physical-faunal surveys of the kind used in this study have the potential to identify streams which may require particular protection.