Predicting fine‐scale distributions of peripheral aquatic species in headwater streams

Abstract

Headwater species and peripheral populations that occupy habitat at the edge of a species range may hold an increased conservation value to managers due to their potential to maximize intraspecies diversity and species' adaptive capabilities in the context of rapid environmental change. The southern Appalachian Mountains are the southern extent of the geographic range of native Salvelinus fontinalis and naturalized Oncorhynchus mykiss and Salmo trutta in eastern North America. We predicted distributions of these peripheral, headwater wild trout populations at a fine scale to serve as a planning and management tool for resource managers to maximize resistance and resilience of these populations in the face of anthropogenic stressors. We developed correlative logistic regression models to predict occurrence of brook trout, rainbow trout, and brown trout for every interconfluence stream reach in the study area. A stream network was generated to capture a more consistent representation of headwater streams. Each of the final models had four significant metrics in common: stream order, fragmentation, precipitation, and land cover. Strahler stream order was found to be the most influential variable in two of the three final models and the second most influential variable in the other model. Greater than 70% presence accuracy was achieved for all three models. The underrepresentation of headwater streams in commonly used hydrography datasets is an important consideration that warrants close examination when forecasting headwater species distributions and range estimates. Additionally, it appears that a relative watershed position metric (e.g., stream order) is an important surrogate variable (even when elevation is included) for biotic interactions across the landscape in areas where headwater species distributions are influenced by topographical gradients.

Seasonal temperature and precipitation regulate brook trout young‐of‐the‐year abundance and population dynamics

“…This study contributes to these knowledge areas by examining mechanisms of population regulations and complements a series of recent brook trout studies that examined distribution patterns using presence and abundance data over a broad spatial scale without rich temporal coverage (e.g. Hudy et al ., ; McKenna & Johnson, ; DeRolph et al ., ; DeWeber & Wagner, ; Kanno et al ., ).…”

Headwater Streams and Wetlands are Critical for Sustaining Fish, Fisheries, and Ecosystem Services

“…Further, headwaters often support ecological specialist as well as threatened taxa not found elsewhere within the river network (DeRolph et al. ; Liang et al. ; Lowe and Likens ; also see The importance of headwaters for imperiled species ).…”

“…Although fish abundance and diversity generally are lower in headwater systems compared to downstream reaches (Schlosser 1987), species composition can be distinct from the rest of the network (Paller 1994). Further, headwaters often support ecological specialist as well as threatened taxa not found elsewhere within the river network (DeRolph et al 2015;Liang et al 2013;Lowe and Likens 2005; also see The importance of headwaters for imperiled species). Fish inhabiting wetlands located outside of floodplains may benefit from greater availability of food resources compared to habitats in other aquatic ecosystems (Snodgrass et al 2001;Baber et al 2002).…”

Fisheries Volume 44 Number 2 February 2019

“…Although fi sh abundance and diversity generally are lower in headwater systems compared to downstream reaches (Schlosser 1987 ), species composition can be distinct from the rest of the network (Paller 1994 ). Further, headwaters often support ecological specialist as well as threatened taxa not found elsewhere within the river network (DeRolph et al 2015 ;Liang et al 2013 ;Lowe and Likens 2005 ; also see The importance of headwaters for imperiled species ). Fish inhabiting wetlands located outside of fl oodplains may benefi t from greater availability of food resources compared to habitats in other aquatic ecosystems (Snodgrass et al 2001 ;Baber et al 2002 ).…”