Leon C. Hinz

Ohio USA stoneflies (Insecta, Plecoptera): species richness estimation, distribution of functional niche traits, drainage affiliations, and relationships to other states

Abstract Ohio is an eastern USA state that historically was >70% covered in upland and mixed coniferous forest; about 60% of it glaciated by the Wisconsinan glacial episode. Its stonefly fauna has been studied in piecemeal fashion until now. The assemblage of Ohio stoneflies was assessed from over 4,000 records accumulated from 18 institutions, new collections, and trusted literature sources. Species richness totaled 102 with estimators Chao2 and ICE Mean predicting 105.6 and 106.4, respectively. Singletons and doubletons totaled 18 species. All North American families were represented with Perlidae accounted for the highest number of species at 34. The family Peltoperlidae contributed a single species. Most species had univoltine–fast life cycles with the vast majority emerging in summer, although there was a significant component of winter stoneflies. Nine United States Geological Survey hierarchical drainage units level 6 (HUC6) were used to stratify specimen data. Species richness was significantly related to the number of unique HUC6 locations, but there was no relationship with HUC6 drainage area. A nonparametric multidimensional scaling analysis found that larger HUC6s in the western part of the state had similar assemblages with lower species richness that were found to align with more savanna and wetland habitat. Other drainages having richer assemblages were aligned with upland deciduous and mixed coniferous forests of the east and south where slopes were higher. The Ohio assemblage was most similar to the well–studied fauna of Indiana (88 spp.) and Kentucky (108 spp.), two neighboring states. Many rare species and several high quality stream reaches should be considered for greater protection.

Modelling of historical stonefly distributions using museum specimens

Stoneflies are imperiled in many regions of the world, but it is often difficult to determine their relative imperilment because of the absence of reliable data. Natural history collections, such as those at the Illinois Natural History Survey (INHS), are sources for such data. We have used Random Forests models of the historical distributions of Illinois stoneflies to better understand their natural range. We have also determined which of 58 georeferenced reach, watershed, and climate summary data appear to explain these distributions. Four species were modelled with relative success, suggesting that this approach has merit and that it may be useful for determining the extent of loss and to informing future conservation efforts for Plecoptera in Illinois and surrounding areas. Expanding the range of this analysis to include adjacent states will improve the models and allow us to model rare species for which enough data were not present from Illinois alone.

Reconstructing the natural distribution of individual unionid mussel species and species diversity in wadeable streams of Illinois, USA, with reference to stream bioassessment

Freshwater mussels are considered one of the most imperiled aquatic species groups in the USA. One of the challenges in protecting and restoring mussel biodiversity effectively is a lack of understanding of their natural distributions at relevant spatial scales. Without this information, assessing the current status of individual species and overall biodiversity or evaluating restoration success is difficult. We compiled records for 45 mussel species and a range of natural environmental variables describing climate, geology, soil, land cover, and watershed topography in Illinois wadeable streams. We used reaches (segments between 2 neighboring tributaries) as the basic spatial unit of the stream network for modeling species distributions with Maxent. We applied these models statewide to all identified wadeable reaches. Stacking the predictions of individual models yielded an estimate of species richness for each reach. The estimates were compared with observed richness from 2 sets of independent sites: 17 sites sampled multiple times over the past 50 to 100 y and 18 sites intensively sampled in 2009 to 2010. The latter set was expected to represent much more impaired mussel assemblages than the former. These sets of sites lost an average of 25 and 46%, respectively, of species expected under natural conditions. Observed occupancy of individual species decreased by 27 and 35%, respectively, from expected natural values. Listed species suffered heavy occupancy loss more frequently than nonlisted species. Estimated mussel species loss was negatively correlated with 2 existing indices of biological integrity. These results, together with maps of natural distributions for individual species and for species richness, will assist with mussel biodiversity conservation and the development and use of mussel-based biological indicators in stream assessment.