Hydroecology of a New Zealand glacier‐fed river: linking longitudinal zonation of physical habitat and macroinvertebrate communities

Abstract

In comparison to European glacier-fed catchments, the hydroecology of New Zealand glacier-fed rivers has received limited attention, despite the Southern Alps markedly different maritime climate, a more precipitation dominated flow regime and an endemic species assemblage. This study linked longitudinal patterns of the physicochemical habitat and macroinvertebrate community along a New Zealand glacier-fed river and compared and contrasted these with understanding of European alpine river systems. Habitat variables and benthic macroinvertebrates were sampled over two consecutive summer melt periods at three sites along the Rob Roy stream, a tributary of the Matukituki River, in Mt Aspiring National Park near Wanaka, South Island. Although habitat stability increased downstream from the glacier terminus (Site R1), disturbance remained a limiting factor of macroinvertebrate abundance and species richness at the lower sites (R2 and R3). An average water temperature increase of 2°C over 3Ð3 km (from R1 to R3) was observed downstream with habitat heterogeneity and species richness highest at the downstream site (R3). The ephemeropterans Deleatidium cornutum and Nesameletus dominated at the upper two sites with the chironomids Eukiefferiella and Maoridiamesa, but became co-dominant at R3 with Deleatidium angustum, where other plecopteran and trichopteran taxa were also observed. Distributions were predominantly limited by temperature, thought to be due to adaptation to disturbance observed in taxa of New Zealand alpine streams. However, the plecopteran Zelandobius, although tolerant of cool temperatures, appeared limited to areas and periods when channel stability was higher. Modification of the conceptual model of the longitudinal zonation of macroinvertebrate taxa (Milner et al., 2001a) is proposed to account for the different species assemblage of New Zealand glacier-fed rivers.

Spatial variability in macroinvertebrate assemblages along and among neighbouring equatorial glacier-fed streams

“…Our levels of benthic CPOM were very high compared with other studies (Lods‐Crozet et al. , 2001; Cadbury et al. , 2010).…”

“…Hydrobiosidae (Trichoptera) were found in all three streams, and the family is abundant and widespread in high Andean (Jacobsen, 2004, 2008) as well as in New Zealand alpine streams (Milner et al. , 2001b; Cadbury et al. , 2010).…”

“…This could explain why different studies on glacier‐fed streams have reached different conclusions on the importance of the same regulating factors, such as chlorophyll a having a greater effect than CPOM on macroinvertebrate assemblages in the Swiss Mutt stream (Lods‐Crozet et al. , 2001), while the opposite was true in the New Zealand Rob Roy stream (Cadbury et al. , 2010).…”

“…For instance, in the Swiss glacier‐fed Mutt stream, maximum water temperature and periphyton biomass had parallel gradients and an almost similar effect on the macroinvertebrate assemblage composition (Lods‐Crozet et al. , 2001), while in the New Zealand glacier‐fed Rob Roy stream, these two variables were uncorrelated and maximum water temperature explained much more of variance in macroinvertebrate assemblages than did algae (Cadbury et al. , 2010).…”

Ecohydrology on the edge: interactions across the interfaces of wetland, riparian and groundwater‐based ecosystems

“…A hydroecological study of a New Zealand glacierfed river (Rob Roy Stream) is undertaken by Cadbury et al (2011), which links longitudinal patterns in physico-chemical habitat to macro-invertebrate communities. New Zealand glacier-fed rivers have received limited attention compared to Europe and North America despite the Southern Alps markedly different maritime climate, a more precipitation dominated river flow regime, and an endemic species assemblage.…”