Effects of pool isolation on trophic ecology of fishes in a highland stream

Abstract

The objective of this study was to examine the effects of pool isolation on fish diet and to answer three questions: Were food resources different or reduced in isolated compared with connected pools? Were fishes more selective and did they increase resource partitioning in isolated pools? Would individuals exhibit increased gastrointestinal tract (GIT) length in isolation to aid nutrient absorption? Benthic macroinvertebrate density and richness were significantly lower in isolated pools compared with connected pools; fishes became more selective and partitioned resources more in isolated pools and all three species showed an increase in GIT length in isolated pools compared with connected pools. With a changing climate predicted to increase intermittency within headwater streams, the results show that these fishes have the adaptive ability to respond and continue to survive.

Ecological factors influencing movement of creek chub in an intermittent stream of the Ozark Mountains, Arkansas

“…Our results, in combination with previous studies on a widely distributed species, suggest creek chub are well adapted to survive in hydrologically dynamic, headwater streams. Creek chub not only have shown the adaptive capability to increase their gut length in intermittent environments (Christian & Adams 2014), but our results also suggest they have adapted movement responses associated with environmental cues of habitat size and complexity. Creek chub in the intermittent reach of North Sylamore Creek exhibited increases in movement (>40% for all mark-recapture samples) and greater distances moved compared to previous studies on creek chub movement (Smithson & Johnston 1999;Belica & Rahel 2008).…”

“…For example, in the Laramie River, Wyoming, creek chub movement between patches was associated with the availability of cover (Belica & Rahel 2008). Creek chub not only have shown the adaptive capability to increase their gut length in intermittent environments (Christian & Adams 2014), but our results also suggest they have adapted movement responses associated with environmental cues of habitat size and complexity. Furthermore, in Little Glayzpea Creek, Arkansas, mobile longear and green sunfish moved from smaller pools more frequently than larger pools (Johnston & Smithson 2000).…”

Effects of episodic stream dewatering on brook trout spatial population structure

“…Predation also can reduce fish abundance in isolated pools from aquatic animals (e.g., northern pike, Esox lucius; Labbe & Fausch, 2000), semi-aquatic animals (e.g., common watersnake; Nerodia sipedon; Lennon, 1961), and terrestrial animals (e.g., great blue heron, Ardea herodias; Steinmetz et al, 2003). Likewise, competition pressures typically increase in isolated pools due to a diminished food supply (i.e., reduced drift biomass; Christian & Adams, 2014) and elevated fish densities, which decrease body size and relative weight (Al-Chokhachy et al, 2022;Hakala & Hartman, 2004).…”

“…Predation also can reduce fish abundance in isolated pools from aquatic animals (e.g., northern pike, Esox lucius ; Labbe & Fausch, 2000), semi‐aquatic animals (e.g., common watersnake; Nerodia sipedon ; Lennon, 1961), and terrestrial animals (e.g., great blue heron, Ardea herodias ; Steinmetz et al., 2003). Likewise, competition pressures typically increase in isolated pools due to a diminished food supply (i.e., reduced drift biomass; Christian & Adams, 2014) and elevated fish densities, which decrease body size and relative weight (Al‐Chokhachy et al., 2022; Hakala & Hartman, 2004). Nonetheless, isolated pools can provide essential refuges for stream fish during drought conditions (Magoulick & Kobza, 2003), the spatial configuration of which can facilitate recovery of fishes after surface flows and habitat connectivity resumes (Lonzarich et al., 1998).…”