Why many aquatic insect species are difficult to identify: implications for stream monitoring and conservation

Abstract

In this article I outline how animal species are defined and discuss some of the difficulties aquatic ecologists have in identifying them. The mayfly genus Deleatidium (Ephemeroptera) is used as example. Implications of these difficulties are considered in relation to the monitoring of streams and rivers and in the context of species conservation. The discovery that river water samples contain a record of the aquatic biota as environmental DNA (eDNA) and major advances in high-input sequencing and metabarcoding, provide an alternative to traditional benthic invertebrate sampling and have the potential to resolve problems with morphological species identification.