Movement of Red Shiner during a regulated, intentional surface‐flow recession

Abstract

Understanding how fish respond to drought and streamflow intermittency is important for designing effective conservation actions. Fish could move to refuge areas prior to intermittency, or be trapped in nearby habitats at the onset. We used mechanical pumps to simulate streamflow intermittency in the Rio Grande, New Mexico. We conducted a 5‐week before–after impact‐only experiment. We seined at 10 sites each week to observe changes in Red Shiner Cyprinella lutrensis abundance and distribution in a 35‐km reach. We conducted two surveys prior to any flow reduction. Next, we reduced flows each week to simulate streamflow intermittency and repeated surveys to identify changes in distribution that would suggest large‐scale movement of Red Shiner to refuge areas. During the first survey, we marked Red Shiner with elastomeric tags to observe movement. In a separate effort, we surveyed all isolated pools that formed after flow reductions for tagged Red Shiner. We observed no patterns that suggested large‐scale movement to refuge areas. Instead, numbers remained steady or increased at all sites in surveys 1 through 4 and declined sharply when sites dried. Tagged fish also supported this conclusion: dispersal models estimated 56% remained within ~0.5 km of the tagging location. We suggest Red Shiner is resilient to drought because of their opportunistic life history and potential for rapid recolonisation, rather than resistant to drought through population‐scale movements to refuge areas. Conservation actions to benefit species threatened by drought must consider the mechanisms of persistence, including both behaviour and life‐history strategy, to be effective.

Effects of flow recession regime on stranding of Rio Grande silvery minnow suggests that conservation actions must overcome evolutionary traps

“…Marking with unique identifiers is difficult, time‐consuming and usually only suitable in laboratory settings (Archdeacon, Remshardt & Knecht, 2009; Neufeld, Blair & Poesch, 2015; Moore & Brewer, 2021). Many small fishes are short‐lived and highly mobile, with low recapture rates of marked fish potentially hindering inferences, particularly on the movements of individual fish or evaluating specific abiotic factors (Platania et al, 2020; Archdeacon, Gonzales & Thomas, 2022; Steffensmeier et al, 2022). As in this study, many inferences on movement rely on population‐level changes (Hoagstrom, Brooks & Davenport, 2008; Walters et al, 2014; Ruppel et al, 2020), but other methods, such as otolith micro‐chemistry (Chase et al, 2015; Duncan, Bramblett & Zale, 2021), genetic analyses of parentage (McBaine, Hallerman & Angermeier, 2022), or the use of tagged hatchery fish (Archdeacon & Remshardt, 2012; Platania et al, 2020) are beginning to allow a more complete understanding of movement behaviour of these small fishes at different temporal and spatial scales.…”

“…In 2018 and 2020, flow recession in the downstream segment was managed by three mechanical pumps that move water from the low‐flow conveyance channel back to the river channel when upstream areas lack surface flows (Figure 1). The pumps have the capacity to discharge ~0.33 m 3 s −1 each, resulting in sustained flows between 0.4 and 0.6 m 3 s −1 at the San Marcial gauge 11 km downstream (Archdeacon, Gonzales & Thomas, 2022). During 2019, no channel drying occurred in either study segments because of prolonged snowmelt runoff.…”

“…In 2018 and 2020, flow recession in the downstream segment was managed by three mechanical pumps that move water from the lowflow conveyance channel back to the river channel when upstream areas lack surface flows (Figure 1). The pumps have the capacity to discharge $0.33 m 3 s À1 each, resulting in sustained flows between 0.4 and 0.6 m 3 s À1 at the San Marcial gauge 11 km downstream (Archdeacon, Gonzales & Thomas, 2022) Intermittent streams undergo a change from a low flow phase (oligorheic) to isolated pools (arheic) to a dry phase with no surface waters (sensu Bonada et al, 2020). These intermittent streamflow regimes can be characterized with multiple metrics, including the fraction of no flow days, first day of no flow and dry-down duration (Hammond et al, 2021).…”

“…Previous research suggests that flow recession rates of 0.1–8 km day −1 (mean ~3 km d −1 ) had little influence on the spatial distribution of adult Rio Grande silvery minnow but were positively correlated with stranding of young‐of‐year fish (Archdeacon & Reale, 2020). Similarly, some marked red shiner Cyprinella lutrensis exhibited upstream movements during controlled flow recession in the Middle Rio Grande, but the population showed no evidence of synchronized movement towards refuge areas, and many were stranded in isolated pools resulting in a significant reduction in abundance (Archdeacon, Gonzales & Thomas, 2022). In an effluent‐dependent stream subject to similar wet‐and‐dry cycles at finer spatio‐temporal scales of drying (0–1.88 km d −1 , mean ~0.8 km d −1 ), drying rate was positively associated with stranding rate of western mosquitofish Gambusia affinis , yet some fish were still stranded in isolated pools regardless of drying rate (Eppenhimer et al, 2021).…”

Fishes move to transient local refuges, not persistent landscape refuges during river drying experiment

“…Understanding how fish populations are affected by streamflow intermittency will be key information for designing effective conservation. For example, some riverine fish species show no clear directional movement to refuge patches during low‐flow events (Archdeacon, Gonzales, Thomas, 2022; Hodges & Magoulick, 2011), becoming trapped in local habitats, which may or may not persist and provide refuge, at the onset of intermittency. Areas that remain wetted can offer refuge (Hopper et al., 2020), allow recruitment (Kereszy et al., 2011) and provide a source of colonists after intermittency; however, these habitats can also transition into ecological traps as water quality and quantity decreases (Archdeacon, Gonzales, Thomas, Rudolph, 2022; Tramer, 1977; Vander Vorste et al., 2020) and density‐dependent interactions increase as a consequence of reduction in volume (Schlosser, 1987).…”