Rapid species replacements between fishes of the North American plains: a case history from the Pecos River

Abstract

This technical paper presents results from pilot field trials conducted on the novel use of a biodegradable jute material to eradicate the highly invasive aquatic macrophyte Lagarosiphon major Ridley from Lough Corrib, Ireland. The results demonstrate the ability of the jute material to comprehensively kill L. major and to restore native macrophyte communities to areas of the lake that were previously overgrown with this priority invasive species. To date, eight indigenous plant species (four charophytes and four angiosperms) have been recorded growing through the loose-weave jute fabric. However, no Lagarosiphon has been recorded as doing so. This material has the potential for broader application in the management of nuisance aquatic weeds and in the restoration of native flora extirpated by these alien species.

Intrafragment riverscape conservation for an imperiled, small-bodied, pelagic-broadcast spawning minnow: speckled chub (Macrhybopsis aestivalis)

“…The same pattern has been observed in similar-aged members of sympatric, pelagic-broadcast spawning species: plains minnow (Hybognathus placitus), Arkansas River shiner (Notropis girardi), Rio Grande shiner (Notropis jemezanus), and N. simus pecosensis (Hoagstrom and Brooks 2005;Hoagstrom et al 2008bHoagstrom et al , 2010. Evidence that distributions of M. aestivalis cohorts consistently shifted toward the relict-ecosystem reach over time suggested survival was higher in the relict-ecosystem reach.…”

“…Although reduced by flood control (Hoagstrom et al 2010), high-flow events in the study area were apparently adequate for critical ecological functions required for successful pelagic-broadcast spawning. These include nutrient enrichment through hyporheic and parafluvial pathways, nutrient concentration in potential nursery areas (i.e., slack waters), propagule retention in potential nursery areas, and provision of "loopholes" from predation and competition (Hoagstrom and Turner 2014).…”

“…This reach was previously identified as a stronghold for pelagic-broadcast spawning minnows because of (1) the concentration of adults there (Hoagstrom and Brooks 2005;Hoagstrom et al 2008bHoagstrom et al , 2010, (2) the wide river channel with relatively high base streamflow (Hoagstrom et al 2008a), and (3) the capacity of the river channel to retain pelagic-broadcast propagules (Dudley and Platania 2007). This relict ecosystem has persisted because of amelioration of downstream dam effects by distance and the restorative influences of uncontrolled tributaries (sensu Stanford and Ward 2001;Sabo et al 2012).…”

“…Extended base-flow periods were disrupted only by sporadic storm-induced flow pulses and by "block" releases that transported irrigation water at a fixed-maximum discharge (ϳ31 m 3 ·s −1 ) for two or, rarely, more weeks at a time (Hoagstrom et al 2010). The study period encompassed a range of flow-regime conditions, including periods with abundant water supply and vice versa (Hoagstrom et al 2008b).…”

Salinity and geomorphology drive long‐term changes to local and regional fish assemblage attributes in the lower Pecos River, Texas

“…Fundulus grandis was rare in the downstream sites with only two specimens collected downstream of Sheffield in October 2011. Hoagstrom et al (2010) discussed the rapid species replacement of Hybognathus amarus by Hybognathus placitus in the Pecos River, an invasion that is ecologically similar to the replacement of F. zebrinus by F. grandis. Pearson correlations of fish species with NMS axes for fish assemblages in the lower Pecos River (Figs 4 and 5).…”