Status and Trends
This study began as a multi-year comparison of the streamflow and water temperature regimes of five headwater basins on the east side of MORA. The streams were chosen for their similarities in drainage area, bedrock geology, climate, and topography. Our results showed that hydrologic regimes varied by an order of magnitude between the basins, a finding that could not be explained by standard parameters such as differences in drainage area. Of the five basins surveyed, Lost, Shaw, and Crystal Creeks exhibited moderated temperature and streamflow regimes associated with a significant amount of groundwater storage. In contrast, Deer and Laughingwater Creeks showed high peak flows in response to storm events and lower baseflows. These basin-wide differences in streamflow response were explained by the greater spatial extent of headwater channel length embedded within depositional landforms and paraglacial landscape features.
We then tested macroinvertebrates as indicator species in relation to colluvial and alluvial channel habitats within cirque basin headwater initiation zones. This research was intended to facilitate development of a new method to identify the hydrologic characteristics of aquatic habitat at intermediate scales. The study was based on the hypothesis that channels associated with paraglacial depositional features (e.g., steep talus footslopes with limited soil development) store and release runoff more slowly than other channel types. The study was designed to evaluate a channel segment sequence commonly found along the channel longitudinal profile in three uncontiguous cirque basins that exhibited similar paraglacial features. We used streamflow, water temperature and insect assemblage type as hydrological metrics.
Our results showed differences in insect assemblage, streamflow, and water temperature between the colluvial and the two types of alluvial channels. Temperatures did not drop below 4⁰ C and above 7⁰C in the colluvial channels throughout the year, while the alluvial channels registered both lower and higher temperatures depending upon the season. Streamflow regimes also varied between channel types, especially during stormflow events.
A total of 9871 aquatic insect specimens were collected during the 8 sampling weeks. Sixty-six taxa groups were used for subsequent multivariate analyses. Taxonomic richness ranged from 8 taxa in the alluvial lake inlet segment of Owyhigh Lakes basin to 28 taxa in the cascade-bedrock lake outlet of Snow Lake basin. Alluvial lake inlet segments displayed generally lower taxonomic richness among segment types in Owyhigh and Snow Lakes basins. All stream segments in Owyhigh lakes basin had lower taxonomic richness compared to the other basins. Alluvial lake inlet segments displayed lower diversity in Owyhigh and Snow Lakes basins. We collected several cold-water, spring-seep, and/or rare taxa, including mayflies Baetis bicaudatus (Dodds), Cinygmula sp., Ephemerella alleni (Jensen and Edmunds), stoneflies Lednia borealis (Baumann and Kondratieff), Despaxia augusta (Banks), Setvena tibialis (Banks), Zapada columbiana (Claassen), and caddisflies Allomyia sp., Chyranda centralis (Wiggins), Ecclisocosmoecus scylla (Ross), Homophylax sp., Neothremma didactyla (Ross), Rhyacophila vagrita (Milne), R. alberta group, and R. rickeri (Ross). Additionally, several Lednia instars were collected that aided in the description of L. borealis (Baumann and Kondratieff, 2010). Most of the cold-water, spring-seep, and/or rare taxa were collected in colluvial stream segment types.