Community Response to Habitat Restoration in Sickle and Bear Creeks, with Emphasis on Mottled Sculpin in Sickle Creek

摘要

Habitat restoration is employed by biologists and managers to improve the natural functionality and value of aquatic resources. Systems suffer impairment from many sources, including excessive fine sediment, which negatively affects substrate composition, channel morphology, aquatic invertebrate habitat, and fish reproduction and recruitment. Primary objectives included monitoring the biophysical response to sediment abatement in the Big Manistee River watershed. Secondary objectives included (1) placing the biophysical response to the restoration in the context of a much larger watershed plan, (2) quantifying seasonal mottled sculpin movement and habitat use in Sickle Creek for 1-year, and (3) determining habitat variables which may predict mottled sculpin distribution in Sickle Creek. Many sampling techniques were used to quantify metrics related to sediment, macroinvertebrates, and fish. Passive Integrated Transponder (PIT) tags were used to determine mottled sculpin seasonal movements. Efforts were often successful in (1) preventing input of sediment, and (2) flushing accumulated sediment from study reaches. Where a positive response in substrate was observed, there was (1) an increase in macroinvertebrate abundance (avg. 218-330 individuals/m2 in Sickle Creek (1st order tributary), and 514-975 individuals/m2 in Bear vii Creek (4th-order tributary)), (2) increased abundance of sensitive taxa (Baetidae), and (3) appearance of additional sensitive taxa (Ueonidae, seven others) from the Ephemeroptera, Plecoptera, and Trichoptera orders. The fish community showed a positive response, based on community metrics including richness, diversity, evenness, and similarity. Pronounced changes in Sickle Creek included the virtual disappearance of creek chub (Semotilus atromaculatus), brook stickleback (Culaea inconstans), and northern redbelly dace (Phoxinus eos), and increased abundance of key taxa (Chinook salmon, O. tshawytscha). Many taxa exhibited upstream longitudinal distribution shifts, especially mottled sculpin (Cottus bairdi). Mottled sculpin seasonal movements were larger than previous estimates (up to 839m, mean 107 ± 26m); distribution was linked to depth of fine sediment and percent medium and large wood. Bear Creek exhibited subtle changes, though we did observe increased CPUE for recreationally important fish taxa including rainbow and brown trout (Oncorhynchus mykiss and Salmo trutta). In conclusion, Sickle Creek responded more rapidly to restoration than Bear Creek, although in both, positive and statistically significant changes were observed.