No abstract

Arctic Grayling Thymallus arcticus were once the dominant salmonid in the Big Manistee River, Michigan, but were extirpated from the watershed around 1900 and from the state of Michigan by 1936, likely due to overfishing, biotic interactions with introduced fish species, and habitat loss occurring largely around the turn of the 20th century. An interest in reestablishing native species by the Little River Band of Ottawa Indians led to an assessment of environmental conditions in a portion of the watershed encompassing 21 km of the Big Manistee River to determine whether suitable Arctic Grayling habitat remains. During summer in 2011–2013, abiotic habitat metrics, including water characteristics, substrate composition, channel profile, channel geomorphic unit, and stream velocity, were assessed across eight tributaries within the watershed. To assess whether abiotic conditions in these tributaries might support Arctic Grayling, the environmental conditions were compared to literature values from rivers where current or historical Arctic Grayling populations have been reported. This comparison, in conjunction with an assessment using a habitat suitability index for Arctic Grayling, indicated that important abiotic conditions were within ranges consistent with those associated with current and past populations of Arctic Grayling in North America. The results of this study will guide potential future reintroductions and indicate that suitable Arctic Grayling habitat does exist in portions of the Big Manistee River watershed, an assessment that will be further refined when coupled with biotic features of the environment. Received September 6, 2016; accepted February 28, 2017 Published online May 9, 2017

Widespread and intensive application of road deicers, primarily road salt (NaCl), in North America threatens water quality and the health of freshwater ecosystems. Intensive use of NaCl can be harmful to sensitive members of freshwater ecosystems such as amphibians. Detection of negative effects of NaCl application has prompted the search for alternative chemical deicers with lower environmental impacts. We conducted a series of 96-h acute toxicity tests to determine the negative sensitivity of larval wood frogs (Rana [Lithobates] sylvatica) to six deicing chemicals: urea (CH(4) N(2) O), sodium chloride (NaCl), magnesium chloride (MgCl(2) ), potassium acetate (CH(3) COOK), calcium chloride (CaCl(2) ), and calcium magnesium acetate (C(8) H(12) CaMgO(8) ). Acetates are sometimes touted as environmentally friendly alternatives to NaCl but have not been examined in enough detail to warrant this designation. When exposed to a range of environmentally realistic concentrations of these chemicals, larvae were least sensitive (i.e., had the lowest mortality rate) to CH(4) N(2) O, NaCl, and MgCl(2) and most sensitive to acetates (C(8) H(12) CaMgO(8) , CH(3) COOK) and CaCl(2) . Our observed median lethal concentration estimates (LC50(96-h) ) for NaCl were over two times higher than values presented in previous studies, which suggests variability in tolerance among R. sylvatica populations. The deicers varied greatly in their toxicity, and further research is warranted to examine the differential effects of this suite of deicers on other species.

Comparative studies of riparian and upland bird communities have focused primarily on larger streams (greater than second order). We examined breeding‐bird assemblages in relation to their proximity to small headwater streams in northern hardwood forests of the Otter River watershed in Michigan's Upper Peninsula, USA. At 10 study sites, we used fixed‐radius point counts to survey bird assemblages and measure forest habitat characteristics along riparian and upland transects. Forest structure and composition differed between riparian and upland areas, with more conifer stems and higher conifer basal area on riparian transects. We detected 46 bird species during 1999 and 2000. During each year, total bird abundance was similar for riparian and upland areas, whereas bird species richness and evenness was higher in riparian areas. When we pooled bird species by foraging guild, we found that foliage‐gleaning birds were more abundant in riparian areas. We found 12 bird species exclusively in riparian areas and only 2 species exclusively in the uplands. The northern parula (Parula americana) and Blackburnian warbler (Dendroica fusca) were among 5 species more abundant on riparian transects, whereas the least flycatcher (Empidonax minimus) and red‐eyed vireo (Vireo olivaceus) were among 5 species more abundant on upland transects. Although the vegetative gradient between riparian and upland habitat was subtle along these first‐ and second‐order streams, breeding‐bird assemblages differed between riparian and upland forests. This suggests that individual bird species respond to vegetative features of even narrow riparian areas. Managers working in northern and mixed‐hardwood forests therefore should consider maintaining habitat diversity in the form of native conifers, even on the smallest first‐order streams.