Aquatic invertebrate species of concern: updated distributions, vital watersheds and predicted sites within USFS Northern Region lands

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An additional 70 stream sites on U.S. Forest Service Northern Region lands in Montana were surveyed for the presence of 20 aquatic macroinvertebrate species meeting USFS Species of Concern (SOC) criteria. No new sites were sampled in Idaho in 2007, but 48 sites were sampled in 2008. Sampling was focused within or adjacent to the Northern Rocky Mountain Refugium (NRMR) area, but also included areas outside of this range. For 2007, nine of the 26 sites sampled (35%) had at least one SOC. In 2008, 36 of the 92 sites sampled (39%) had at least one SOC. The majority of sites with SOC were characteristic of headwater forested, high-gradient, fishless streams, with the exception of Vermillion River and Beaver Creek, which were lower-gradient, salmonid bearing streams. These surveys, as well as compilation of other records, resulted in 22 new stream locations harboring USFS aquatic macroinvertebrate SOC across three sub-watersheds within the Lolo National Forest. Detections from the 2006–2008 surveys and other compiled records were used to create models of species’ predicted distributions in order to assist with future sampling efforts and management decisions. The predictive models demonstrated that the majority of USFS SOC occur in moderate- to higher-elevation (>1700m), small tributary streams with wetter precipitation regimes. Surveys and predictive models support the conclusion that the number of USFS aquatic SOC increases near the Montana-Idaho border, especially within the Clearwater and Lolo National Forest Refugium area. The authors recommend protecting these critical watershed habitats (e.g., headwater NRMR areas) for these macroinvertebrate SOC from future road development and habitat degradation by following RCA management practices for protecting riparian areas, as well as designating the upper St. Regis basin of the Lolo National Forest, in particular the upper tributaries of Big Creek and Deer Creek downstream to, and including, Chromie Creek, a candidate on the Research Natural Area list for Montana. Extensive surveys were performed on USFS lands for the western pearlshell mussel, Margartifera falcata, a USFS Species of Interest (SOI). MTNHP and USFS biologists surveyed 230 stream reaches on or within 1 km of the Beaverhead-Deerlodge, Bitterroot, Gallatin, Helena, Kootenai, Lewis and Clark and Lolo National Forests. Only 16 viable populations from 11 streams were documented (6 exceptional and 10 with good viability). Western pearlshell populations were present in an additional 80 stream reaches, but all appeared to have poor viability. These findings add additional evidence of significant statewide population declines for this species.

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ELECTRONIC FILE - Zoology: Invertebrates

Suggested citation: Stagliano, David, M., and Bryce A. Maxell. 2010. Aquatic Invertebrate Species of Concern: Updated Distributions, Vital Watersheds and Predicted Sites within USFS Northern Region
Lands. Report to USDA Forest Service, Northern Region. Montana Natural Heritage Program,
Helena, MT. 30 p. plus appendices.

SWAP (2/19/2016) citation:
Stagliano DM, Maxell BA. 2010. Aquatic invertebrate species of concern: updated distributions, vital watersheds and predicted sites within USFS Northern Region lands. Helena (MT): Montana Natural Heritage Program. 30 p. Report prepared for US Forest Service, Northern Region. Agreement No.: 05-CS-11015600-036. [accessed 2015 Jun 1]. http://mtnhp.org/reports/2008RegionSOCAqInvert.pdf