Factors Associated with Detection and Distribution of Native Brook Trout and Introduced Brown Trout in the Driftless Area of Iowa

Abstract

Fish populations at the fringe of their geographic range often inhabit marginal habitats and are vulnerable to ecological disturbances, such as species invasion, land cover conversion, and climate change. The Driftless Area of northeastern Iowa, USA represents the southwestern edge of the native range of Brook Trout Salvelinus fontinalis, where endemic populations have been greatly reduced due to habitat degradation and introduced Brown Trout Salmo trutta. Therefore, documenting Brook Trout occurrence patterns at the southern tip of their range may prove useful for the conservation of peripheral populations. We fitted single-species occupancy models at multiple spatial scales to estimate the relative effects of biotic (e.g., Brown Trout density) and habitat (instream, riparian, and watershed) variables on Brook and Brown Trout occupancy to predict their current distribution in the Iowa Driftless Area. Species occurrence and physical habitat data were collected at 138 stream segments of the Upper Iowa, Yellow, and Little Maquoketa River watersheds (8-digit hydrologic unit codes) during May-September in 2018 and 2019. Brook Trout occupancy was low (19 of 138 sites) and affected by local (instream and riparian) habitat covariates, particularly August--September stream temperatures, but no adverse effects of Brown Trout density were detected. Brown Trout occupied 54% of streams (74 of 138 sites), and occupancy was influenced by a combination of local-scale (mean stream velocity, percentage of run macrohabitat, and August-September stream temperatures) and catchment-scale (percent forested land cover and upstream catchment area) habitat variables. Our results provide evidence that instream thermal conditions are a critical determinant of Brook Trout distribution, while Brown Trout exhibit plasticity in habitat suitability and increased colonization in areas where they are introduced. Given the dependence of Brook Trout on cold stream temperatures, the projected loss of thermally suitable habitats due to climate change may facilitate their replacement by naturalized Brown Trout at the southwestern extent of their range.

Differences in Native and Invasive Fish Larval Occupancy and Detection Probabilities in the Upper Mississippi River

“…2 ΔAIC c from the top model as competitive in analyses. Finally, we calculated detection probabilities under increasing sampling size (cumulative detection probability) using the most supported detection model (e.g., Kelly et al, 2021).…”

“…Within fisheries, occupancy and detection modeling has been primarily used to describe distribution of adult fishes (Potoka et al, 2016;Schumann et al, 2020;Sullivan et al, 2018;), but models are plastic and have been adapted to evaluate age-0 fish habitat use (Burdick et al, 2008;Falke et al, 2010Falke et al, , 2012, timing of reproduction events associated with environmental conditions (Falke et al, 2010;Peoples and Frimpong, 2011;Pritt et al, 2014), and recruitment of cryptic invaders (Weber & Brown, 2019). These models also provide sample size requirements to achieve desired detection probabilities, improving sampling designs and monitoring programs (Kelly et al, 2021;Kuehne & Olden, 2016;Rodtka et al, 2015). Consequently, occupancy models can serve as a useful tool for assessing reproductive dynamics of bigheaded carp along leading edges of invasion where reproduction may be limited, and spawning events can be brief and difficult to detect.…”

Sicklefin Chub (Macrhybopsis meeki) and Sturgeon Chub (M. gelida) Temporal and Spatial Patterns from Extant Population Monitoring and Habitat Data Spanning 23 Years

“…The PSPAP and MRBFS used different benthic trawls; the PSPAP used a 4.8 m-wide otter trawl (OT16; [27]), and the MRBFS used a 2 m bottom trawl (BT; [26,29]). To structure data for an occupancy model with spatially replicated visits [37], the full definition of a site was a macrohabitat within a river bend sampled during a particular year. Each river bend was only visited once during the fish community season within a year.…”

Applying High-Resolution Satellite and UAS Imagery for Detecting Coldwater Inputs in Temperate Streams of the Iowa Driftless Region

“…Canoe Creek is a HUC 10 watershed that covers approximately 172 km 2 , ranges in elevation from 219 m to 419 m, and contains roughly 733 km of streams including Canoe Creek, North Canoe Creek, and their tributaries [41]. Land use and cover within the watershed is predominantly pasture and cropland with tracts of deciduous forest [42]. The karst topography that dominates this region creates an eroded valley-ridge patchwork with limestone and dolomite rock Therefore, the objectives of our study were to (i) use optical VHR imagery collected during winter seasons to delineate open water reaches of streams in a northeastern Iowa watershed using semi-automatic and manual approaches, (ii) validate the coldwater stream status of selected reaches using water temperature data, fish community data, instream habitat data, and UAS imagery, and (iii) use the extent of coldwater stream segments identified in this study to recommend updates to existing stream classification datasets.…”

“…Canoe Creek is a HUC 10 watershed that covers approximately 172 km 2 , ranges in elevation from 219 m to 419 m, and contains roughly 733 km of streams including Canoe Creek, North Canoe Creek, and their tributaries [41]. Land use and cover within the watershed is predominantly pasture and cropland with tracts of deciduous forest [42]. The karst topography that dominates this region creates an eroded valley-ridge patchwork with limestone and dolomite rock outcroppings [43] and an extensive network of coldwater streams, providing suitable habitat for coldwater fishes [44].…”