Assessment of artificial bryophytes for invertebrate sampling in two New Zealand alpine streams

Abstract

An artificial substratum invertebrate sampler, designed to mimic bryophytes, is described and evaluated. Invertebrate and algal colonisation of these structures was rapid, and invertebrate abundance peaked after 4 weeks. Following an exposure period of 2 months, total invertebrate density, taxonomic richness, and densities of many taxa were similar to those usually found on natural bryophytes, although densities of Nematoda, Limonia hudsoni (Tipulidae), and an empidid were lower. Taxa that are characteristic of riffles (e.g., Deleatidiwn sp. and Nesameletus sp. (Ephemeroptera), or Stenoperla prasina and Zelandobius sp. (Plecoptera) did not colonise the “stems” of the artificial bryophytes very extensively, but were present on the bases of these structures and on the underlying bedrock. TWINSPAN classifications identified a strong similarity between faunas of the artificial bryophytes and their real counterparts, but dissimilarity to faunas associated with riffles. Thus, the artificial bryophytes successfully mimicked their real counterparts as a habitat for invertebrate assemblages.

Keywords:

• aquatic bryophytes
• riffles
• invertebrates
• periphyton
• artificial substrata
• colonisation
• streams