Plains Topminnow Fundulus Sciadicus Research Articles

Large-scale dispersal patterns and habitat use of plains topminnow Fundulus sciadicus: implications for species conservation

Movement behaviors attributed to spawning, dispersal, or altered habitat availability are essential to the ecology of many lotic fishes and, although considerable research has described movements of sport fish, little is known about the movement patterns of nongame species. Streams and rivers, wherein plains topminnow Fundulus sciadicus are prevalent, occur in a nonequilibrium state in which habitat patches are sporadically created and lost due to hydrologic variability. This results in regular extirpation and need for recolonization of many plains fishes, including plains topminnow. Species persistence, therefore, is dependent on tolerances to fluctuating habitat conditions and life-history traits that allow dispersal over large areas. To better understand the regional distribution of plains topminnow, we monitored large-scale dispersal patterns and habitat use of two introduced populations in Nebraska. In 2011 and 2012, plains topminnow were marked using visible implanted elastomer (VIE) marks and released at the center of two 3000-m study reaches. Populations were sampled monthly from April to November in 2011 and April through September in 2012 to describe movement patterns and habitat use. Plains topminnow were highly mobile, consistently associated with select habitat features, and the estimated individual home range exceeded standard sampling reach distances by nearly four times. The movement of plains topminnow occurred at greater rates and to distances further than known for similar species. These large-scale movements likely help maintain connectivity among populations within stream drainages and facilitate recolonization of regularly extirpated habitat patches. In this context, species movement may be critical to the maintenance and potential recovery of populations of this and other rare lotic fishes.

Conservation Status of Five Headwater Stream Specialists in South Dakota

Native stream fish zoogeography has changed substantially across North America during the last century because habitat degradation, stream fragmentation and introductions of nonnative species have led to numerous extinctions, extirpations, and altered distributions. Insufficient information regarding imperiled species often results in reactive, rather than proactive, management, and knowledge of species status and ecology is critical in identifying conservation priorities. We used fish collection records and a habitat assessment to update the status of five fishes of conservation interest in South Dakota (Northern Redbelly Dace Chrosomus eos, Finescale Dace Chrosomus neogaeus, Northern Pearl Dace Margariscus nachtriebi, Blacknose Shiner Notropis heterolepis, and Plains Topminnow Fundulus sciadicus). We compiled records from previous collections within the White, Little White, and Keya Paha River Basins in South Dakota as well as adjoining and neighboring drainage basins in Nebraska. We also sampled fish and habitat at 42 stream reaches within the White, Little White, and Keya Paha river basins during 2010–2012, focusing on tributary streams. We detected all target species except for Finescale Dace. All species preferred tributary streams over larger rivers (third order or greater). All target species except Blacknose Shiner exhibited patchy distribution and abundance patterns, normally occurring at low relative abundance where present but occasionally detected at moderate to high relative abundance. Each target species was limited to landscapes with perennial, springfed streams that are not present in neighboring drainages. This study updates the distribution of conservation listed species, identifies landscape level habitat filters, and offers guidance for conservation and research efforts.

Culture of Plains Topminnow in a Pond Constructed for Species Conservation

AbstractThe plains topminnow Fundulus sciadicus appears to be experiencing reductions in geographic range and local abundance, which has led to regional protection throughout its native range. Conservation of this species may require introductions to reestablish populations at known historic locations. Therefore, a pond was constructed during September 2007 to house a refuge population of plains topminnow in Nebraska. A total of 123 plains topminnow were stocked into the pond in two stocking events during 2008. Plains topminnow populations were sampled throughout 2008 and mark–recapture population estimates were conducted after reproductive events during 2009 and 2010 resulting in estimates of 9,844 ± 1,698 (mean ± SD) and 3,974 ± 452 plains topminnow, respectively. Mean fish weight was used as an estimate of pond biomass, which was 28.4 kg/ha in 2009 and 44.9 kg/ha in 2010. Reproduction was first observed in 2008 and in each following year, and a strong year‐class was produced in 2009, which suggested there were factors that limited reproduction in the other 2 years. Extensive culture may be an effective way to rear plains topminnow and related species. However, more research is needed to determine factors that affect year‐class strength and production.

Changes in range-wide distribution of plains topminnow Fundulus sciadicus

Globally, riverine fishes are affected by degradation of habitat, stream alterations, lost stream connectivity and introduction of non-native species. The plains topminnow Fundulus sciadicus, a small stream-dwelling fish, currently does not have a federal conservation status in the USA; however, anecdotal reports have suggested its decline for the last 20 yr. Our goals were to evaluate the validity of its reported decline and to determine the current range-wide status of this species. We identified 927 historical sites (1889�1999) of occurrence and compiled recent records or re-visited 667 sites (2000�2010). We found plains topminnow at 189 (28.0%) of these sites. Although Nebraska represented the center of distribution and included 66.7% of all histori- cal sites, plains topminnow were only found at 34.4% of historical sites, with the largest declines observed in the Platte and Republican River drainages. Current sampling efforts in Colorado, Mis- souri, Oklahoma, South Dakota and Wyoming found similar declines. In Iowa and Kansas, plains topminnow was not found, whereas potential increases in distribution were observed in a single drainage in Minnesota and Wyoming. In addition to our sampling efforts, we repeatedly sampled 40 sites within Nebraska to determine detection probability. Detection probabilities for plains top- minnow were consistent at 0.76 ± 0.05 (mean ± SE) among sites that were sampled with a single visit. Further research is needed on the species and the potential threats to its occupation of sites, as no singular cause for decline seems plausible. Observed threats include degradation and loss of habitat and shifts in species assemblages towards generalist non-native species.

Low variation but strong population structure in mitochondrial control region of the plains topminnow, Fundulus sciadicus

The plains topminnow Fundulus sciadicus is a freshwater killifish endemic to the Great Plains of North America. Rising concerns for future viability of this species have prompted recent changes in its conservation status. In this study, the results of a range-wide population genetic survey based on the sequence of entire mitochondrial control region (CR) are presented. A total of 181 fish were collected from 11 sites in Nebraska and 10 sites in Missouri spanning the distribution range of the species. Seven polymorphic sites were found in the 966 base pairs of the CR, and only nine unique haplotypes were detected among all fish. Phylogenetic analysis and statistical parsimony networks identified two distinct clades. The first included fish in the Osage, Gasconade and Spring River drainages in Missouri, while the second included individuals from Nebraska and the Lamine River in Missouri, although the Lamine River is much closer to the other Missouri sites than to the Nebraska sites. Pair-wise F(ST) and average population distances indicated that populations from most drainages are genetically distinct, as 93% of the total molecular variance was attributed to among-drainage effects. Four sites within the main distributions of this species and a highly disjunct site from the south-western portion of the range are suggested as potential targets for conservation.

Patterns of Morphological Variation of Salsuginus yutanensis (Monogenea: Ancyrocephalidae) over Space and Time

Salsuginus yutanensis occurs on the gills of the plains topminnow Fundulus sciadicus Cope. The fish of this species have been found to vary morphologically and biochemically among disjunct populations. Morphological characteristics of the sclerotized parts of S. yutanensis were examined from 3 localities in Nebraska, over a 2-yr collecting period. Analysis of variance was used to assess morphological variation with respect to site and date. Worms from 2 localities, Keith and Saunders counties, differed significantly for most characters considered. A third site, also in Keith County, contained worms for which measurement means tended to be intermediate between those in the other 2 sites. This site-related difference was maintained over a pattern of broad seasonal variation and suggests that the site-related differences are of evolutionary origin. If this interpretation is true, then the parasite populations likely are isolated in a manner analogous to those of the host. However, differences due to effects of temperature on worm development were not ruled out as possible explanations for the observations although consistent temperature differences between the sites are unlikely, given the nature of the habitats studied.