Aquatic Insects

Twice a summer, in June and again in August, Inletkeeper staff train citizen scientists to collect, identify, and record the abundance and diversity of aquatic insects in a selection of our monitoring streams. The numbers and types of aquatic insects, affectionately referred to as ‘bugs’, in our streams can tell us a great deal about water quality. We use these data, along with our citizen-collected water chemistry data, to look at changes and trends in water quality over time within the Kachemak Bay and Anchor River watersheds.

Macroinvertebrates (insects and other invertebrates that can be seen with the naked eye) are well suited for monitoring studies due to their abundance, diversity, and relative ease to sample and analyze. In most streams, the macroinvertebrate community is dominated by larval insects which live a completely aquatic existence, feeding on organic matter like fallen leaves and other invertebrates. Each insect group has specific requirements for food, substrate, temperature, and dissolved oxygen concentrations. The presence or absence of particular insects is a good indicator of certain water quality and habitat conditions.

This kind of monitoring is termed "biological assessment" - an evaluation of streams using biological surveys. The use of indicator species helps to characterize the current status of the biological condition in a watershed. Mayflies (Ephemeroptera), stoneflies (Plecoptera), and caddisflies (Trichoptera) are referred to as EPTs and are considered the key indicator species of stream health. These types of insects do not tolerate pollution, and you won't find them in streams that have poor habitat or water quality. These three groups are found in most streams in Alaska. In 2003, Cook Inletkeeper began incorporating EPA Rapid Bioassessment Protocols, refined for use in Alaska by the Environment and Natural Resources Institute (ENRI) at University of Alaska Anchorage, into our citizen-based water quality monitoring program.

Each one of Inletkeeper's Citzens' Environmental Monitoring Program annual water quality report includes a review of the previous years' biological assessment, and all baseline water quality reports for monitoring sites review the full set of bioassessment data, if it's available for that site.

2010 Biological Assessment Summary

From the 2010 Year In Review (check back in July 2011 for data from June 2011 sampling!):

Our summer Stream Team of specially-trained CEMP volunteers conducted biological monitoring, also known as bug assessment, at 5 CEMP sites in 2010: No Name Creek, Lower Diamond Creek, Upper Woodard Creek, Bridge Creek, and Upper Miller Creek. 2010 was the first year of biological monitoring at these sites, with the exception of 1 monitoring event at Lower Diamond Creek in 2004. Biological monitoring is done twice per summer, once in June and again in August, to capture seasonal variability in bug communities.

Water quality ratings (WQRs) are calculated for each site based on the types of bug communities present. This rating takes into account the different types of bugs that are found in the stream and how those types typically respond to pollution or disturbance. Higher WQRs indicate that there were more sensitive bugs present in the stream than tolerant bugs. The highest WQRs in 2010 were at No Name Creek in June (65.0) and Lower Diamond Creek in August (60.1). The WQRs at Upper Woodard Creek in 2010 (June = 58.5, August = 52.8) were higher than at Lower Woodard Creek at similar times of the summer in 2009 (June = 45.7, August = 40.1). Upper Miller Creek had the lowest WQRs in both June (39.6) and August (29.7).