—Authors' Response—

Medley, C. Nicolas; Kehmeier, Jon W.; Myers, Orrin; Valdez, Richard A.

doi:10.1080/02705060.2009.9664348

Cited by 2 publications

(2 citation statements)

References 9 publications

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“…However, BSM populations still persist in fragmented and highly modified river reaches. Alternatively, other studies have concluded that BSM species that spawn on the rising limb of a flood hydrograph take advantage of egg retention mechanisms associated with channel storage and flood attenuation that promotes entrainment and settling of drifting eggs in areas of low-velocity flow near spawning sites (Fluder et al, 2007;Medley et al, 2007;Medley, 2009;Medley et al, 2009;Widmer et al, 2012). These species may further enhance egg retention by spawning in remnant low-velocity river channels or inundated floodplain habitats (Gonzales et al, 2012) when available.…”

Section: Egg Biology and Life Historymentioning

confidence: 99%

“…No direct observations of broadcast spawning have been made in situ in these river systems (Moore, 1944;Bottrell et al, 1964). Studies using artificial eggs released in the river channel have shown that highly modified river reaches in the Rio Grande and Pecos River can transport BSM eggs great distances downstream (<30 to >150 km) (Dudley and Platania, 2007;Medley et al, 2007Medley et al, , 2009Widmer et al, 2012). The magnitude of egg displacement is highly variable, dependent upon the complex interaction between discharge, channel dimensions, channel complexity, flow attenuation, channel storage, and river floodplain connectivity, but egg retention may be very efficient when coincident with ascending high flows and floodplain inundation.…”

Section: Magnitude Of Downstream Egg Driftmentioning

confidence: 99%

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Review and reinterpretation of Rio Grande silvery minnow reproductive ecology using egg biology, life history, hydrology, and geomorphology information

Medley

Shirey

2013

Ecohydrology

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To inform management actions to recover the endangered Rio Grande silvery minnow (Hybognathus amarus, RGSM), we (1) calculated the terminal settling velocities of newly expelled and water-hardened RGSM eggs for the observed range of suspended sediment concentrations and water temperatures in the Rio Grande, New Mexico, USA, and (2) reviewed RGSM reproductive ecology in the context of egg biology, the species' life history, and the historic and contemporary hydrology and geomorphology of the Rio Grande. Results show that in a naturally functioning riverine environment, the location and timing of spawning, the ontogenic stage of egg development, and habitat-specific differences in sediment and temperature that influence egg-settling rates interact to (1) prevent egg suffocation, (2) promote egg entrainment in clear, warm, productive floodplain habitats, and (3) limit downstream population displacement. Our research suggests that the RGSM is primarily a demersal, floodplain spawning species that evolved eggs that are secondarily buoyant in high-sediment environments rather than a main channel, pelagic broadcast-spawning species with an evolved long-distance, downstream drift phase, as previously reported. The current high magnitude of egg drift is hypothesized to be an artefact of contemporary river management and channelization, leading to reduced lateral connectivity, floodplain abandonment, and habitat degradation. Conservation actions implemented to restore historic channel form and reconnect low-velocity backwater and floodplain habitats are recommended. In the absence of a documented upstream migration of adult fish, removal of barriers to a presumed upstream movement is unlikely to provide immediate benefits to RGSM.

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Section: Egg Biology and Life Historymentioning

confidence: 99%

Section: Magnitude Of Downstream Egg Driftmentioning

confidence: 99%

Review and reinterpretation of Rio Grande silvery minnow reproductive ecology using egg biology, life history, hydrology, and geomorphology information

Medley

Shirey

2013

Ecohydrology

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Sampling Efficiency of the Moore Egg Collector

Worthington¹,

Brewer²,

Grabowski³

et al. 2013

N American J Fish Manag

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Quantitative studies focusing on the collection of semibuoyant fish eggs, which are associated with a pelagic broadcast‐spawning reproductive strategy, are often conducted to evaluate reproductive success. Many of the fishes in this reproductive guild have suffered significant reductions in range and abundance. However, the efficiency of the sampling gear used to evaluate reproduction is often unknown and renders interpretation of the data from these studies difficult. Our objective was to assess the efficiency of a modified Moore egg collector (MEC) using field and laboratory trials. Gear efficiency was assessed by releasing a known quantity of gellan beads with a specific gravity similar to that of eggs from representatives of this reproductive guild (e.g., the Arkansas River Shiner Notropis girardi) into an outdoor flume and recording recaptures. We also used field trials to determine how discharge and release location influenced gear efficiency given current methodological approaches. The flume trials indicated that gear efficiency ranged between 0.0% and 9.5% (n = 57) in a simple 1.83‐m‐wide channel and was positively related to discharge. Efficiency in the field trials was lower, ranging between 0.0% and 3.6%, and was negatively related to bead release distance from the MEC and discharge. The flume trials indicated that the gellan beads were not distributed uniformly across the channel, although aggregation was reduced at higher discharges. This clustering of passively drifting particles should be considered when selecting placement sites for an MEC; further, the use of multiple devices may be warranted in channels with multiple areas of concentrated flow.Received August 8, 2012; accepted October 12, 2012

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—Authors' Response—

Cited by 2 publications

References 9 publications

Review and reinterpretation of Rio Grande silvery minnow reproductive ecology using egg biology, life history, hydrology, and geomorphology information

Review and reinterpretation of Rio Grande silvery minnow reproductive ecology using egg biology, life history, hydrology, and geomorphology information

Sampling Efficiency of the Moore Egg Collector

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