Niangua Darter Monitoring Report 2010

Transcription

1 Niangua Darter Monitoring Report 2010 Longest Niangua Darter on record (total length 132 mm/5.2 in); Little Pomme de Terre River Doug Novinger and Jamey Decoske Missouri Department of Conservation Resource Science Division Tavern Creek Road crossing, June 1, 2010

2 Summary We performed annual monitoring surveys for the federally listed Threatened, Missouri listed Endangered Niangua Darter (Etheostoma nianguae) during June 2 through October 1, We collected data with the overall goals of describing spatial and temporal trends in Niangua Darter population densities and size structure, associated darter species diversity, and multi-scale habitat characteristics. Data collected during 2010 represented the 9th consecutive year of our surveys in fixed monitoring sites. We also provide an update of monitoring ongoing to evaluate several low water crossing improvement projects that have been underway since We found that population densities of adult-sized Niangua Darters as well as the number of monitoring sites occupied by Niangua Darters were reduced range-wide during 2010, with evidence for weak but detectable longer-term declines in densities in Little Niangua and Maries river watersheds. Distribution was particularly limited in Tavern Creek where just three sites were occupied. The recent decline in Niangua Darter populations and distributions appeared to be correlated with high flows that have occurred frequently since Our qualitative observations suggested that fine sediment concentrations were higher in many locations, particularly in Tavern Creek, compared to pre-2008 conditions. Frequent precipitation and fluctuating flows may have caused increased erosion and siltation that would degrade habitat quality. High flows also may be related to other hydrologic and environmental characteristics that could negatively interact with Niangua Darter habitat quality or physiological ecology to cause declines in population densities and distributions (reduced reproductive success, displacement, increased energetic costs). Although reduced detection probabilities could contribute to the appearance of population declines, the estimates we obtained during 2009 and 2010 and personal observations do not support this as a generic explanation. However, it does highlight the importance of accounting for detection to accurately and efficiently evaluate population trends of Niangua Darters in the future. General reductions in darter species richness measured in all of the watersheds during 2009 to 2010 paralleled the declines in Niangua Darter populations. The replacement of several low water crossings has generally led to favorable changes upstream of the new clear spans including increases in the abundance of Niangua Darters, improvements in habitat quality such as increased non-pool habitat and particle sizes that would be expected to benefit the darter species, and increased darter species diversity. Additional benefits to darter populations related to removal of a passage barrier (e.g. increased gene flow and access to habitat) were emphasized by the documented movement of darters upstream past a replaced crossing. However, there can be at least short-term negative impacts to darters and habitat downstream of crossings due to the transfer of accumulated fine sediments. Future surveys will allow us to evaluate the rate and degree of recovery as downstream reaches stabilize. Niangua Darter Monitoring Report 2010 Page 2

3 Introduction and Methods We performed annual monitoring surveys for the federally listed Threatened, Missouri listed Endangered Niangua Darter (Etheostoma nianguae) during June 2 through October 1, Personnel involved in field work included Doug Novinger, Jamey Decoske, and Resource Technicians Jason Bals, Miles Walz-Salvador, Alex Foster, and Dylan Spruance. We collected data with the overall goals of describing spatial and temporal trends in Niangua Darter population densities and size structure, associated darter species diversity, and multi-scale habitat characteristics. Data collected during 2010 represented the 9th consecutive year of surveys in monitoring sites. We also provide an update of monitoring ongoing to evaluate several low water crossing improvement projects that have been initiated since Similar sampling goals and methods were employed toward evaluating differences before and after road crossing improvement and between sites upstream and downstream of crossings. Surveys in low water crossing sites occurred during June and early July, whereas surveys in other monitoring sites occurred during July through September. Monitoring Protocol We surveyed 29 fixed monitoring sites distributed among five major Osage River tributary watersheds inhabited by populations of the Niangua Darter: Little Niangua River (n=6), Maries River (7), Niangua River (5), Pomme de Terre River (5), and Tavern Creek (6) watersheds (Table 1;Figure 1). Two sites monitored during previous years were not surveyed due to persistent livestock intrusion and poor water quality (LNR040, PDT050). We also surveyed sites associated with 12 low water road crossings, with a site established upstream and downstream of each crossing (Table 2; Figure 1). Some sites downstream of crossings were also fixed monitoring sites. Monitoring sites were m in length and partitioned into riffle, run, glide/shallow pool, pool edge, and deep pool habitat patches (Arend 1999). Glides and shallow pools were combined because the two types of habitat often occurred together, were similar in many respects, and it was difficult to determine where one type transitioned into the other. Pool edges were identified by a somewhat gentle slope of predominately clean gravel, often with water willow (Justicia sp.), bordering one or sometimes both sides of a deep pool. All non-deep pool habitats within the site boundaries were sampled. We recorded data on a Trimble Nomad hand-held computer with built-in GPS capability using an ArcPad geodatabase that included separate layers for site (a polygon enclosing the stream reach to be sampled), habitat (a line segment drawn to represent each habitat patch), and Niangua Darters (a point created at each focal observation location). Upon arriving at the downstream boundary of a site, we measured lateral secchi disk visibility, water temperature, and recorded date, weather conditions, and start time by editing the site layer data table. The data recorder next created a line segment in the GIS layer for the first habitat patch to be sampled and prepared to accept data communicated by the snorkelers. Fish sampling was performed by two snorkelers moving upstream through the habitat patch in a zigzag pattern at a rate of 3 m/min. In very shallow areas (<10 cm), counts were conducted by slowly walking and visually scanning the stream bottom with the aid of polarized sunglasses. When a Niangua Darter was sighted, snorkelers placed a color-coded marker at the location to indicate the relative size of the fish using the following length categories: small (<66 mm), medium (66 90 mm) and large (>90 mm) (Mattingly and Galat 1997). Smallsized Niangua Darters were assumed to be juveniles, whereas medium- and large-sized individuals were assumed to be adults (Pflieger 1978). Niangua Darter Monitoring Report 2010 Page 3

4 We used multiple-pass, depletion/removal methods (White et al. 1982) to allow for estimating Niangua Darter detection probabilities, population sizes, and precision of the estimates for each habitat patch. When an adult-sized Niangua Darter was sighted, the snorkeler attempted to capture it using aquarium nets, usually one held in each hand. An additional snorkeler who did not actively search for Niangua Darters often assisted, and by surrounding a fish with four nets we had a high degree of success at capturing it. Niangua Darters captured during this first pass through the habitat patch were placed in a floating net bag (3.2 mm mesh). Small-sized Niangua Darters were counted but not captured due to the increased risk of injury to juvenile fish and difficulties associated with holding them in the net bags. After the habitat patch had been searched, snorkelers performed additional passes according to the following guidelines: Stop after 1 pass if # Niangua Darters = 0 or 1 Stop after 2 passes if o pass 2 # Niangua Darters = 0 o pass 1 + pass2 # Niangua Darters 3 o depletion from pass 1 to 2 > 80% If time is limited Stop after 3 passes if no single pass # Niangua Darters > 3 The guidelines were selected to accelerate progress through habitat patches where Niangua Darters were sparse and sample size would be too low for meaningful population estimates. During each pass, snorkelers employed a comparable degree of effort by thoroughly searching the same locations within the habitat patch. Small-sized Niangua Darters were ignored during subsequent passes to avoid doublecounting. Additional net bags were used as necessary to reduce risks associated with overcrowding and for counting fish from different passes. After sampling of a habitat patch was completed, Niangua Darters were returned to locations with cover and distributed among original collection points at densities approximating those observed during sampling. Following a suitable distance downstream of the snorkelers, the data recorder created a point in the GIS layer at each Niangua Darter marker location. After noting the sampling pass number and fish size category, the recorder used a calibrated wading staff and current velocity meter (Marsh McBirney Flo- Mate 2000) to measure depth (nearest cm), mean water column velocity (nearest cm/s with the flow sensor at 60% depth), and bottom velocity (nearest cm/s with the flow sensor resting on substrate). The recorder also visually estimated the dominant substrate type based on a modified Wentworth classification of particle diameter including fines (< 2 mm), gravel (2-15 mm), pebble (16-63 mm), cobble ( mm), boulder (> 256 mm), and bedrock (Cummins 1962). Habitat data were only measured during the first pass because it was assumed that fish locations during subsequent passes were biased by the initial disturbance. We recorded the presence of all darter species observed by snorkelers as they searched the habitat patch, and counted bluestripe darters (Percina cymatotaenia) that occurred in the Niangua River and are listed as a species of conservation concern (S2). We recorded the length of each habitat patch and at three equally-spaced points at mid-channel measured stream width, depth, mean column water velocity, and dominant substrate type. We also classified the percentage length of each habitat patch bordered on either side by wetted water willow, dense algal blooms, streambank erosion (e.g. cutbanks generally without attached vegetation and eroding toe), livestock use, and other significant disturbances such as gravel removal operations. Habitat percentage classes included 0-5%, 6-25%, 26-50%, 51-75%, %. Measurements of linear distances were made to the nearest m with a laser rangefinder or visual estimation for distances < 10 m. Niangua Darter Monitoring Report 2010 Page 4

5 Methods used to monitor sites associated with low water crossings were identical with methods used in standard monitoring sites with the addition of a Wolman pebble count to ascertain patterns in the sizes of rocky substrates and estimation of the embeddedness of the rocky substrate matrix by fine sediments (Bain 1999). Both measurements are relevant to determining habitat suitability for small, benthic fishes that forage, find shelter, and reproduce dependent on characteristics of the interstitial spaces found on the stream bottom. The pebble count was performed by measuring the intermediate axis (nearest mm) of the particle encountered at toe-point as we walked transects crossing the stream channel diagonally from one high-water bank to the other. Each transect crossed a 50-m length of stream and particles were selected with a frequency that resulted in approximately 20 measurements per transect. At each point where a particle was measured, we also estimated the embeddedness or degree to which the larger rocky particles were surrounded or covered by fine sediment according to a percentage scale of 0-25%, 25-50%, 50-75%, and %. Statistical Analyses Population estimates were derived from the multi-pass, removal counts for adult-sized Niangua Darters using Program CAPTURE version 16 May 1995 found in Program MARK (Mark and Recapture Population Estimation version 6.0 by G. C. White). Typically, we used the Zippin M(b) model to obtain estimates for population size, estimate precision, and capture probability; however, for very small sample sizes the Jackknife M(h) model was used. We believe the population model assumption of closure was satisfied because Niangua Darter movements are generally limited, movement among habitat patches was often restricted by natural barriers (high flow, excess depth, lack of cover, unsuitable substrate), and our sampling method was of short duration and minimally intrusive to avoid pushing darters ahead of snorkelers. We used an information-theoretic approach (Anderson 2008) to evaluate temporal trends in the abundance of Niangua Darter adults in each watershed separately. We performed time series analysis by fitting linear mixed-effects models (Pinheiro and Bates 2000) and using the lme model formula available in the nlme package of the statistical program R v.2.9 (Crawley 2007). For abundance data, we used the single-pass ( ) and first pass ( ) counts of adult Niangua Darters totaled for each site per 100 m of habitat searched (nd100). We compared four models including a model with site as a random effect but no year effect (null model): and three models with year as a fixed effect: model0 <- lme(nd100~1,random=~1 site,method="ml"), modelx <- lme(nd100~year,random=~1 site,method="ml"). Models with a year effect included one that did not account for temporal autocorrelation, one that used a first order autoregressive autocorrelation structure, and one that used an autoregressive moving average structure. We compared the four models simultaneously by considering which model had the lowest AIC (using the AICc correction for small sample sizes), the relative magnitudes of the delta AIC and model Akaike weights or probabilities, and how convincing was the evidence ratio, the ratio of the weight of the best model with time to the probability of the model without time. Niangua Darter Monitoring Report 2010 Page 5

6 To describe patterns of co-occurrence between Niangua Darters and other darter species we calculated Sorensen distance using R (dsvdis function in package labdvs), a measure that ranged from 0 (similar) to 1 (dissimilar) using species presence/absence data across all years and sites. We evaluated changes in Niangua Darter populations, darter species richness, and habitat that occurred in relation to low water crossing replacements by inspecting means and variation for pre- and postreplacement time periods. For most crossings it was only possible to collect a single pre-replacement sample, therefore we visually compared the pre-replacement value with the mean and variation of postreplacement values and considered the degree of overlap and direction of change. Particle diameter and embeddedness measurements derived from pebble counts were summarized by calculating the mean of measurements for each 50-m transect for a particular year. The means for each transect were then averaged to obtain a mean and variation for each transect by time period, either pre- or postcrossing replacement. Results and Discussion Annual Population Monitoring Compared to previous years, counts of Niangua Darters during 2010 were reduced and totaled 176 compared to 218 during 2009 (Table 3). Overall reductions occurred in all size classes and all five watersheds. Numbers of small-sized Niangua Darters (young-of-year) observed during surveys are influenced by survey date, are particularly variable due to environmental conditions, and tend to be more difficult to detect because they use shallow edge habitats that are difficult to survey. To avoid such biases, we focused on the abundance of medium and large (adult-sized) Niangua Darters as a more accurate representation of population trends (Table 4). Numbers of adult-sized Niangua Darters decreased in many sites compared to 2009, most dramatically in LNR000 (downstream of Howards Ford), MAR050 (downstream of Sestak slab) and MAR070, PDT090 (Little Pomme de Terre River), and most sites on Tavern Creek. Monitoring history lows of 10 adult-sized Niangua Darters were found in Maries River sites and only 3 adult-sized Niangua Darters were found in Tavern Creek. Relationships between mean population densities of adult-sized Niangua Darters (#/100 m) and year (averaged across sites) suggested at least a short-term decline in all watershed (Figure 2, panels 1 to 5). Recent downturns may reflect the increases in stream discharges that have occurred range-wide since 2008, shown for the Maries River in Figure 2 (panel 6). We found evidence for temporal patterns in three of the five watersheds (Table 5). There was strong evidence that population densities in Little Niangua River, and to a lesser extent in Maries River, declined during 2002 to Model evidence ratios were relatively high with negative slopes estimated for trend; however, the 90% 1-sided confidence limit on the slope estimates for both watersheds included zero. Taken together these results confirm that detectable declines have occurred but were weak relative to the degree of variation in the data and with a rate of decline that was not significantly different from a hypothesis of no change. Declines in population densities since 2008 appeared to be driving the downward trends. By contrast, the best model indicated an increasing trend in population densities in Pomme de Terre River, though zero was included in the confidence limit on the slope. The best models for population densities in Niangua River and Tavern Creek did not include a time component. Graphical trends in population densities for sites in each watershed are provided for Little Niangua (Figure 3), Maries (Figure 4), Niangua (Figure 5), Pomme de Terre (Figure 6), and Tavern (Figure 7). Niangua Darter Monitoring Report 2010 Page 6

7 With regard to Little Niangua River, three of six sites had population densities that decreased during LNR000_00 (downstream of Bannister Hollow Rd), often boasting the highest population densities, has experienced two consecutive years of steep decline. In Maries River, population densities declined in six of seven sites and most notably remained depressed in MAR050_00 (downstream of County Rd 521 aka Sestak Slab). Population densities in Niangua River were uniformly low and variable. Population densities increased in four of five sites on Pomme de Terre River, though the site on Little Pomme de Terre River has experienced two consecutive years of decline. Tavern Creek sites were marked by a decline in population density in five of six sites. Our conclusion based on these analyses is that population densities of adult-sized Niangua Darters were reduced range-wide during 2010, with evidence for weak but detectable longer-term declines in Little Niangua and Maries river watersheds. In particular, high flows during 2008 through 2010 may be negatively affecting Niangua Darter populations. Unfortunately, it is not possible for us to distinguish between true declines in population density and declines in the probability of detecting Niangua Darters. Both factors may be related to hydrologic conditions, with high flows potentially redistributing fish, restructuring habitat, inundating peripheral cover, and increasing search area. Distribution The number of monitoring sites occupied by Niangua Darters (21 of 30) was reduced during 2010 compared to 2006 to 2009, but near the mean across all 9 years (20.7)(Table 6). Distribution was most reduced in Tavern Creek where Niangua Darters were found in only three of six sites, the lowest number of sites occupied in that watershed during this study. Niangua Darters were found in all sites surveyed on Pomme de Terre watershed. At a smaller scale, the proportion of habitat patches occupied by Niangua Darters during 2010 also was reduced in all watersheds with the exception of Pomme de Terre (Table 7). The most dramatic reductions were found for Maries River and Tavern Creek, where only 9 and 4% of patches were occupied (vs. means of 29 and 28%, respectively). Multiple-pass Depletion/Removal Population Estimates During 2009 and 2010, we used multiple-pass depletion/removal methods to obtain Niangua Darter population estimates and detection probabilities for each habitat patch and to evaluate the suitability of single-pass counts for accurately representing larger population trends. Population estimates were summarized for each monitoring site by adding the estimates and, separately, variances for each patch (Table 8). We found sufficient numbers of Niangua Darters to perform population estimation and calculate detection probability in 13 or 23% of the patches inhabited by Niangua Darters. In most watersheds, one or two sites contributed disproportionately to the watershed totals for population size and variance. Population estimates were reduced from 2009 to 2010 in all watersheds, ranging from a decline of 26% in Little Niangua to 87% in Tavern Creek. We investigated the potentially interacting effects of watershed and habitat characteristics on population estimates and detection probabilities and found somewhat different patterns in each watershed. Detection probabilities averaged 0.67 (SE=0.09) and continued to be higher at sites in Little Niangua and Maries watersheds (Table 8). Water clarity assessed with lateral secchi measurements were notably lower in Niangua River sites (mean ± SE = 0.9 ± 0.1) but similar in other watersheds (Little Niangua 1.8 ± 0.3, Maries 2.0 ± 0.3, Pomme de Terre 1.7 ± 0.4, Tavern 1.9 ± 0.2). Secchi measurement had a weak effect on detection probability when 2009 and 2010 data were combined; a 1-m increase in secchi corresponded to a 0.1 increase in detection probability across a range of 0.7 to 3.0 m for lateral secchi visibility (linear model, slope ± SE = ± 0.046, p = 0.04, adj. r 2 = 0.08, n = 40). Population densities (population estimate/100 m) tended to be higher in glides, runs, and pool edges and detection Niangua Darter Monitoring Report 2010 Page 7

8 probabilities higher in shallow pools and riffles though these were extremely minor differences (Table 9). The amount of physical structure might be expected to affect detection probabilities, for example if Niangua Darters used water willow for concealment cover. Runs tended to offer the highest concentrations of water willow compared to other habitat types but had intermediate detection probabilities. Overall, we could not distinguish a clear relationship between percent water willow in habitat patches and detection probability. We evaluated how well the first pass totals, representing the relative abundance data collected during 2002 to 2008, related to population estimates that were determined during 2009 and We found a positive relationship between the two measures; however, there was appreciable residual variation around the regression line with wide prediction intervals (Figure 8). Pass 1 totals were on average (mean ± SE) 61.1 ± 2.7% (range %) of the population estimates. While these results suggest that single-pass samples may fluctuate in a pattern related to real changes in the population, there is substantial variation that would reduce the effectiveness of using pass 1 totals to accurately detect trends. The loss of precision and accuracy inherent in relying on single-pass counts as a measure of relative abundance can be expected to reduce the statistical power of time series analyses, prolonging the time period required for monitoring to detect population declines. In summary, our evaluation suggested that single-pass methods may not provide reliable data, are limited in utility because detection probabilities are not accounted for, and would be inefficient in the long-term due to the variability of the data. Consequently, we do not recommend depending on singlepass/relative abundance measures to accurately assess population trends of Niangua Darters in the future. In particular, if managers require an accurate estimate of the number of Niangua Darters in a population (e.g., to judge the effect of low water crossing replacement on the number of Niangua Darters occupying a particular stream reach) then multiple-pass depletion/removal methods are an appropriate method. However, for range-wide monitoring of populations and distributions, methods incorporating an occupancy modeling approach would likely be more efficient and informative. Habitat Associations Data describing habitat characteristics were collected at the point locations where Niangua Darters were observed (depth, current velocities, substrate type/size) and associated with each habitat patch (amounts of water willow, algae, erosion, livestock impact). Patterns of microhabitat use related to Niangua Darter point locations do not imply preference because we did not measure the availability of microhabitat (which would have required intensive sampling). However, we can compare patterns of microhabitat use among size classes of Niangua Darters to investigate size- or age-related shifts in use. Small-sized Niangua Darters displayed a pattern of microhabitat use distinctive from the adult size classes. Compared to larger-sized Niangua Darters, small-sized individuals were most frequently found in edge habitat patches (45% vs. 31 and 18% for medium and large sizes; chi-square test of patch-type vs. Niangua Darter size category: = 24.1, p = 0.002). Large- and medium-sized Niangua Darters were more likely to occur in riffles and glides. Small-sized Niangua Darters used point locations that were more shallow (depth mean ± SE = 28.4 ± 0.7 cm) and with slower mean column and bottom velocities (mean column = 3.4 ± 0.4, bottom = 1.8 ± 0.2 cm/s) compared to the larger size classes (Figure 9; linear mixed models with significant size effect and multiple comparisons, p<0.05). Large and medium-sized Niangua Darters were found at similar depths (large: depth = 38.1 ± 0.8 cm; medium: 37.4 ± 1.0 cm); however, large-sized Niangua Darters were associated with faster velocities (mean column = 12.4 ± 0.9, bottom = 6.2 ± 0.5 cm/s) compared to medium-sized fish (mean column = 7.2 ± 0.8, bottom = 3.9 ± 0.5 cm/s). Most (>80%) Niangua Darters were found over gravel to pebble-sized substrates, with small- Niangua Darter Monitoring Report 2010 Page 8

9 sized individuals more often associated with gravel compared to larger size classes (Figure 9). Overall, large-sized Niangua Darters utilized a wider range of habitat characteristics probably due to relatively greater swimming ability, foraging plasticity (prey size, type), and reduced vulnerability to gape-limited predators. Niangua Darter population densities (population estimate/100m) were higher in habitat patches with >25% of the patch length bordered by water willow. Water willow is often associated with stable stream channels and provides structure that numerous aquatic organisms use for cover, foraging habitat, etc. We often observed Niangua Darters associated with the edge of water willow stands where substrates were relatively free of fine sediment. Significant concentrations of algae were rarely found to impact >5% of habitat patch length. High flows and cool temperatures during much of spring and early summer during 2009 and 2010 probably diluted nutrient inputs and inhibited algae growth and attachment to substrates. In the few patches with significant algae, the number of Niangua Darters observed was low with the highest population densities occurring in habitat patches with algae <50%. The degree of erosion of stream banks affected <25% of habitat patch length in 75% of patches. There was no discernible relationship between the amount of bank erosion and Niangua Darter population densities. Evidence of significant livestock intrusion into monitoring sites during 2009 and 2010 was limited. As described for algae, high flows and cool temperatures may have played a part in reducing the frequency of stock entering the stream corridor as livestock damage has appeared more severe during previous years. Nevertheless, Niangua Darters were not observed in the few (3%) habitat patches with >50% livestock impact. Species Associations The diversity of darter species is similar among the watersheds inhabited by Niangua Darter with the exception of the bluestripe darter that only is found in the Niangua River watershed. Monitoring during 2002 to 2010 has documented the occurrence of 11 darter species, including Niangua Darter. The maximum darter species richness recorded in habitat patches was 8 in Pomme de Terre watershed and 9 in Little Niangua, Maries, Niangua, and Tavern watersheds with annual means ranging from 5.3 to 8.8 species. We have found a consistent pattern in each watershed for higher darter species diversity in habitat patches occupied by Niangua Darters (Figure 10). There did not appear to be significant temporal trends in richness though there were general reductions in all of the watersheds during Niangua Darters were most likely to co-occur with Ozark logperch and were commonly found with four additional species including greenside darter, banded darter, orangethroat darter, and rainbow darter (Table 10). Missouri saddled darter and fantail darter tended to inhabit faster-flowing habitats than Niangua Darter. Stippled darter were more often found in slow to moderately flowing habitats but were difficult to detect because they were frequently concealed in rocky substrates or structural cover along the stream s edge. We likely underestimated the presence of that species. Finally, bluestripe darter and johnny darter were relatively uncommon and difficult to detect by snorkeling because they inhabit deeper habitats and may be associated with dense vegetation (especially bluestripe darter). Niangua Darter Monitoring Report 2010 Page 9

10 Low Water Crossing Monitoring Monitoring Niangua Darter populations, habitat, and fish community characteristics in conjunction with low water crossing improvements has followed the same protocols associated with sampling established monitoring sites with the exception of some additional habitat measurements (pebble counts). In some instances, monitoring sites were already associated with the crossings. Data analyses and presentation emphasize temporal comparisons before and after crossing replacement, and spatial comparisons downstream (site00) and upstream (site01) of each crossing. A list of the crossings monitored during 2010 including location information and analysis years can be found in Table 2. Niangua Darter population abundance data as determined by single-pass snorkeling are presented for all crossings in Table 11 and Table 12. For the time being, evaluations of population changes are based on these data. Population estimates obtained during 2009 and 2010 removal surveys are presented in Table 13; future evaluations of population changes will incorporate these data as appropriate. Percentages of habitat patches occupied by Niangua Darters are summarized in Table 14 to allow assessment of site-scale shifts in distribution. Changes in the mean percentage of non-pool habitat (excluding deep pools and pool edge) are presented in Table 15 and provided the basis for an assessment of macrohabitat alterations, whereas changes in darter species richness (also in Table 15) were used to evaluate the suitability of habitat for the darter component of the fish community. Trends in substrate composition determined during pebble counts and based on particle size can be found in Figure 11 (Little Niangua), Figure 12 (Maries and Niangua), and Figure 13 (Tavern). Trends based on embeddedness are in Figure 14 (Little Niangua), Figure 15 (Maries and Niangua), and Figure 16 (Tavern). Status and results for each site are presented separately by watershed: Little Niangua BANNISTER00,01 (Kolb Hollow Rd, Bannister Ford ). This crossing was first surveyed during 2009 and was replaced later that year. Estimated population sizes of Niangua Darters decreased during 2010, from 34 to 15 upstream and from 65 to 24 downstream. Niangua Darters occupied from 80 to 100% of habitat patches during both years. The length of non-pool habitat increased by 65% upstream of the crossing and 15% downstream. Mean darter species richness increased from 7 to 8 upstream. Particle diameters generally increased both upstream and downstream of the crossing. Embeddedness increased downstream of the crossing, perhaps as fine sediments previously deposited upstream of the old crossing were mobilized and transferred downstream. We will continue monitoring this site during GREENS00,01 (Green Ford Rd, Greens Ford ). Greens Ford was first sampled during 2008 and the crossing was replaced later that year. Abundance of adult-sized Niangua Darters from single-pass samples have declined slightly upstream of the crossing post-replacement but increased downstream. Changes in population estimates obtained during 2009 and 2010 indicate a similar pattern. Upstream of the crossing, 100% of the habitat patches sampled was occupied by Niangua Darters pre- and postcrossing replacement with a slight increase in the percentage of patches occupied post-replacement downstream. There was no non-pool habitat upstream of the crossing documented during our surveys, only pool edge habitat. Downstream of the crossing the length of non-pool habitat has increased by 10%. Mean darter species richness increased substantially upstream following replacement (from 2 to 5) with a lesser increase downstream (7 to 8). Particle diameter has remained relatively low and embeddedness high in response to the crossing replacement (an apparent increase downstream). We will continue monitoring this site during GRISWALD00,01 (Green Ridge Dr, Griswald Ford ). Griswald Ford was first sampled during 2008 and the crossing was replaced later that year. Niangua Darter single-pass mean abundance has increased Niangua Darter Monitoring Report 2010 Page 10

11 post-replacement from 1 to 3.5 in the site upstream of the new crossing and from 2 to 10.5 downstream of the crossing. Population estimates during 2009 were 4 upstream and 31 downstream compared to 3 and 11 during Niangua Darters occupied higher percentages of habitat patches sampled following crossing replacement, increasing from 17 to 50% of the habitat patches surveyed upstream and from 25 to 100% of the habitat patches downstream. The percentage of non-pool habitat increased by 29% upstream and 40% downstream of the crossing. Darter species richness increased both upstream (from a mean of 4 to 8) and downstream (6 to 7.5). Changes in particle size and embeddedness were relatively minor with an indication of slight increases in embeddedness downstream. We will continue monitoring this site during LAKOTA00,01 (Lakota Rd over Thomas Creek). This crossing was first monitored during 2004 and replaced later that year. We completed initial monitoring during We did not observe Niangua Darters either upstream or downstream of the crossing prior to replacement or during the first sample following; however, small numbers of Niangua Darters (1-6) were found both above and below the crossing each year during 2006 through 2009 with similar mean single-pass abundances (1.2 upstream and 2.2 downstream). Population estimates during 2009 were 3 and 2 in upstream and downstream sites. The mean percentage of habitat patches occupied by Niangua Darters were 10% upstream and 15% downstream of the crossing (all following replacement). Non-pool habitat increased by 31% upstream and 100% downstream yet there were only minor changes in mean darter species richness (from 4 to 6 species upstream and 6 to 6.2 downstream). Particle diameter increased slightly in the 100 m immediately upstream of the crossing with minimal indication of consistent changes elsewhere. There were no detectable changes in embeddedness. Overall, our monitoring suggests that replacement the Lakota Rd crossing was associated with increased use of habitat patches upstream and downstream of the crossing by a small number of Niangua Darters and benefits to habitat for darters that included increased non-pool habitat and some increased roughness of the substrate upstream of the crossing. LNR000_00,01 (Bannister Hollow Rd, Howards Ford ). We began monitoring these sites during 2008 and the crossing was replaced later that year. We also have sampled an established monitoring site downstream from Howards Ford since Single-pass abundance of Niangua Darters increased substantially upstream immediately following crossing replacement. Post-replacement population estimates declined by approximately 50% in both upstream and downstream sites during Upstream of the crossing, Niangua Darters have on average occupied 89% of the habitat patches surveyed post-replacement compared to 33% during 2008 (pre-replacement). In a concurrent study of Niangua Darter movement, McCleary (2010) found that two Niangua Darters marked downstream of the crossing before replacement had moved upstream of the crossing following replacement. During 2010, we observed that three Niangua Darters marked downstream of the crossing had moved upstream of the crossing for total distances of 500, 652, and 864 m. One Niangua Darter marked upstream of the crossing was resighted downstream of the crossing representing a total distance of 235 m. Two of the fish were marked during 2008, the other three during Amounts of non-pool habitat have increased by 39% in the upstream site and 15% in the downstream site following replacement of the crossing. Mean darter species richness increased dramatically from 2 to 8 upstream but declined from 10 to 8.5 downstream. Particle sizes have generally increased upstream of the crossing and decreased downstream. Embeddedness remained high upstream and has increased downstream. The changes in substrate composition correspond to the transfer of fine material downstream. We will continue to monitor this site during Niangua Darter Monitoring Report 2010 Page 11

12 LNR030_00,01 (Hickory Co Rd 96 at Muleshoe CA). We began surveys at this crossing during 2004 and it was replaced during We completed initial monitoring during 2009 when the last survey upstream of the crossing occurred; however, we surveyed downstream during 2010 as it is an established annual monitoring site that has been sampled since Pre-replacement, single-pass mean abundance of Niangua Darters was 1 upstream of the crossing and increased to 7.8 following replacement. Prereplacement abundance was 13 downstream of the crossing and declined to 8 post-replacement. Population estimates during 2009 were 71 upstream and 3 downstream, increasing to 10 downstream during The large numbers of Niangua Darters found upstream were associated with water willow in pool-edge habitat and an expanding area of glide habitat created by lowering of the formerly impounded pool. Niangua Darters occupied similar percentages of habitat patches before and after replacement of the crossing both upstream (67% during both time periods) and downstream (59% before and 61% after replacement, reducing to 57% when 2010 data were included). The percentage of non-pool habitat increased both upstream by 67% and downstream by 28%. Darter species richness was similar before and after crossing replacement in both upstream and downstream sites. Particle diameters changed minimally in relation to the crossing replacement; however, embeddedness declined substantially upstream of the crossing and increased downstream of the crossing. Overall, replacement of this crossing has been associated with remarkable increases in the abundances of Niangua Darters upstream of the crossing apparently in response to improvements in habitat quality that included increased glide and suitable pool-edge as well as a reduction in the amount of fine sediment. We noted indications of reduced abundances of Niangua Darters and habitat quality downstream of the crossing apparently related to the transfer of fine sediment following replacement of the crossing. LNR060_00,01 (Hickory Co Rd 200, Erikson Slab ). We began surveys at Co Rd 200 during 2007 and the crossing was replaced later that year. Initial monitoring was completed during The site downstream of the crossing is an established monitoring site that has been sampled since Since 2008, we have measured a slight increase in single-pass abundances of Niangua Darters upstream of the crossing, from 3 to a mean of 4.3, with a mean population estimate of 6.5 during 2009 and Downstream of the crossing, the abundances of Niangua Darters declined from 35 to a mean of 5.3 with a mean population estimate of 2. The percentage of habitat patches occupied by Niangua Darters increased slightly from 17% to 20% upstream of the crossing but declined from 89% to 29% downstream of the crossing following replacement. The percentage of non-pool habitat has increased by 36% upstream of the crossing and by 32% downstream. Mean darter species richness increased slightly from 6 to 7 upstream but decreased from 9 to 8 downstream. Particle diameters were little changed either upstream or downstream of the crossing two years following replacement; however, embeddedness increased greatly in both upstream and downstream sites. We suspect reduced abundances of Niangua Darters downstream of the crossing despite increases in non-pool habitat are related to the transfer of fine sediments following replacement of the crossing. The apparent increase in fine sediments upstream of the crossing indicated by high values for embeddedness may be related to ongoing streambank erosion problems we have observed in that reach. SCHOOLRD00,01 (School Rd). We first surveyed this crossing during 2010 and it was replaced later the same year. Niangua Darters were not found in either the site upstream or downstream of the crossing during Amounts of non-pool habitat were high in both sites (386 m upstream of the crossing and 405 m downstream) with similar, moderately low numbers of darter species observed (5 species in each site). Particle diameters were consistently low and embeddedness high upstream and downstream of the crossing. We will continue to monitor this site during Maries Niangua Darter Monitoring Report 2010 Page 12

13 MAR050_00,01 (Osage Co Rd 521, Sestak Slab ). This crossing was first surveyed during 2009 and may be replaced during A monitoring site downstream of the crossing has been sampled since Niangua Darters have not been observed in the site upstream of the slab; however, a significant population has existed downstream though only 1 Niangua Darter was observed during The mean population estimate was 6.5 (during 2009 and 2010) and Niangua Darters occupied 34% of the habitat patches downstream. Darter species richness was higher downstream (mean = 8.5) compared to upstream (5.0). Particle diameter increased slightly within proximity to the bridge but was otherwise similar upstream and downstream. Embeddedness was nearly 100% throughout the reach. We plan to continue monitoring this crossing during Niangua NIR060_00,01 (Steelman Rd at Big John CA). We first surveyed this crossing during 2005 with additional pre-replacement samples during 2006 and 2007; the crossing was replaced during fall, Initial monitoring surveys were completed during The site downstream of the crossing includes an established monitoring site that has been sampled since Adult-sized Niangua Darters were not detected either upstream or downstream of the crossing during pre-replacement samples (1 small-sized individual was observed downstream during 2006). However, 2 adult-sized Niangua Darters were found upstream of the crossing during 2008 and 3 were found downstream during post-replacement sampling during Percentages of non-pool habitats increased by 66% upstream of the crossing and by 9% downstream following replacement. Mean darter species richness increased from 5.7 to 6.7 both upstream and downstream. Particle diameters increased m upstream of the crossing following replacement but have changed minimally in other portions of the sites. Embeddedness has increased markedly beginning approximately 150 m upstream of the crossing and progressing throughout the 300- m reach downstream. The shifts in substrate composition likely reflect down-cutting and transfer downstream of fine sediments from the large pool immediately upstream of the crossing. WILLIAMS00,01 (Benton Branch Rd, Williams Ford ). We began monitoring Williams Ford during 2009 and completed a second pre-replacement survey before the crossing was replaced during summer, We found 1 large and 1 small Niangua Darter upstream of the crossing but none downstream during Niangua Darters were not observed during 2010 though one adult Niangua Darter was observed just outside of the site boundary downstream of the crossing (C. Fuller, pers. comm.). Nonpool habitat was limited in general but more abundant downstream of the crossing with several deep pools found in both sites. Mean darter species richness was 6.5 upstream and 7 downstream and included Bluestripe Darters in both sites. Particle diameters were generally low, with some large rock (e.g. boulders) in the bluff pool upstream of the crossing and occasional bedrock in a pool downstream. Embeddedness values were somewhat higher upstream in association with the deep pool. We plan to continue monitoring this crossing during Tavern BARREN00,01 (Sequoia Rd over Barren Fork). We first surveyed this crossing during 2008, with an additional survey during 2009 before the crossing was replaced later that year. The survey during 2010 was the first post-replacement survey. The mean single-pass abundances of Niangua Darters prereplacement was 1.5 upstream and 16 downstream of the crossing. During 2010, 1 Niangua Darter was found upstream and 9 downstream of the crossing. Population estimates determined during 2009 (prereplacement) were 2 and 47 compared to 1 and 13 during 2010 (post-replacement) upstream and downstream of the crossing, respectively. Niangua Darters occupied a mean of 21% of habitat patches surveyed upstream of the crossing and 60% downstream pre-replacement compared to 11 and 63% post-replacement. The amount of non-pool habitat declined slightly downstream of the crossing. Mean Niangua Darter Monitoring Report 2010 Page 13

14 darter species richness was 6.5 upstream and 6.0 downstream of the crossing pre-replacement with 7 and 6 species observed during the post-replacement survey. Particle diameters appeared to have increased 100 to 150 m upstream and within 50 m downstream of the crossing. Embeddedness increased markedly with increasing distance downstream of the crossing. We will continue monitoring this crossing during MASSMAN00,01 (Ridge Rd, Massman Slab ). We began monitoring Massman Slab during 2005 and the crossing was replaced later that year. Initial post-replacement surveys were completed during A small number of Niangua Darters (1 or 2) were observed downstream of the crossing during 2005 to 2007, though none were found during 2008 and Niangua Darters have yet to be observed upstream of the crossing. Replacement of the crossing had dramatic impacts on habitat, corresponding with an increase in non-pool habitat of 93% upstream of the crossing following elimination of a large, impounded pool. We found that the amount of non-pool habitat downstream of the crossing increased by 11%. Mean darter species richness increased from 3 to 5.5 upstream of the crossing and was essentially unchanged downstream (7 to 6.8). Particle diameters have increased within 200 m upstream of the crossing but changed minimally downstream. In response to the transfer of fine sediment, embeddedness declined upstream of the crossing and increased through much of the site downstream. TAVERNRD00,01 (Tavern Creek Rd). This crossing was first surveyed during 2010 and replaced later that year. We found 3 adult Niangua Darters downstream but none upstream of the crossing. Non-pool habitat accounted for 48% of the site sampled upstream of the crossing and 88% downstream. Three darter species were observed upstream of the crossing and 7 species downstream. Particle diameters were slightly higher downstream of the crossing with the exception of the first 50 m where there were frequent outcrops of bedrock. There were relatively similar, high degrees of embeddedness both upstream and downstream. We will continue to monitor this crossing during WATKINS00,01 (Watkins Ford Rd). This crossing was first surveyed during 2010 and replaced later that year. We discovered 9 Niangua Darters downstream of the crossing (estimated population size = 16) with 30% of the habitat patches occupied. Niangua Darters were not found upstream of the crossing where 32% of the site was composed of non-pool habitat compared to 84% of the site downstream. Darter species richness was 3 upstream and 9, a high level of diversity, downstream. Particle diameters were reduced within 200 m upstream of the crossing, increasing within 100 m downstream in relation to scour. Embeddedness of substrates was reduced immediately downstream of the bridge as well. We will continue to monitor this crossing during In summary, we observed strong evidence for benefits related to the replacement of low water crossings during initial, short-term monitoring periods. Favorable changes were greatest upstream of replaced crossings and included increases in the abundance of Niangua Darters and occupied habitat patches, improvements in habitat quality such as increases in the amount of non-pool habitat and particle diameter that would be expected to benefit the darter species, and increased darter species diversity. Of the 15 crossings we have monitored, 10 crossings were replaced with clear span bridges with at least 1 year of post-replacement monitoring. We found that the single-pass abundance of adultsized Niangua Darters was on average unchanged or increased compared to pre-replacement in 7 sites upstream of crossings and in 4 sites downstream of crossings. The percentage of habitat patches occupied by Niangua Darters was unchanged or increased in 8 sites upstream and in 5 sites downstream of crossings. The percentage of non-pool habitat increased both upstream and downstream of crossings following replacement in 9 sites and declined both upstream and downstream in 1 site. Darter species Niangua Darter Monitoring Report 2010 Page 14

15 richness was unchanged or increased in 9 sites upstream of crossings and in 4 sites downstream. Overall, these patterns are consistent with improved habitat quality that occurred upstream of several crossings as flowing habitats were restored and habitat heterogeneity increased through reduction or elimination of large pools. To a lesser degree, similar beneficial changes in habitat characteristics occurred downstream of replaced crossings; however, the transfer of fine sediments downstream may have had detrimental effects to darters and habitat in several sites as indicated by reduced Niangua Darter abundances and darter species richness combined with increased embeddedness of substrates. Future monitoring will hopefully reveal that negative changes to darters and habitat downstream of crossings diminish as high flow events redistribute materials and result in fewer differences between upstream and downstream reaches. The movement of darters upstream past a replaced crossing highlighted other potential benefits to Niangua Darters related to removal of these passage barriers including increased gene flow and access to additional suitable habitat. In fact, some of the initial increases in Niangua Darter abundances upstream of crossings may reflect emigration from downstream into newly created habitat. Conclusions We found that population densities of adult-sized Niangua Darters as well as the number of monitoring sites occupied by Niangua Darters were reduced range-wide during 2010, with evidence for weak but detectable longer-term declines in densities in Little Niangua and Maries river watersheds. Distribution was particularly limited in Tavern Creek where just three sites were occupied. The recent decline in Niangua Darter populations and distributions appeared to be correlated with high flows that have occurred frequently since 2008, however we only speculate about causal relationships. Our qualitative observations during surveys suggested that fine sediment concentrations were higher in many locations, particularly in Tavern Creek, compared to pre-2008 conditions. Perhaps the persistent precipitation and high flows has resulted in increased erosion and the introduction of fine sediments that would degrade habitat quality. High flows may be related to a number of other hydrologic and environmental characteristics that could negatively interact with Niangua Darter habitat quality or physiological ecology to cause declines in population densities and distributions (reproductive success, displacement, energetic costs). Although we cannot rule-out reduced detection probabilities via higher flows as an apparent cause of population declines, the estimates we obtained during 2009 and 2010 and personal observations do not support this as a generic explanation. However, it does highlight the importance of accounting for detection to accurately and efficiently evaluate population trends of Niangua Darters in the future. General reductions in darter species richness measured in all of the watersheds during 2009 to 2010 paralleled the declines in Niangua Darter populations. Our monitoring results showed that replacement of low water crossings can lead to favorable changes, particularly upstream of crossings, including increases in Niangua Darter populations, enhanced quality of benthic habitat, and increased darter species diversity. Additional benefits to darter populations related to removal of a passage barrier (e.g. increased gene flow and access to habitat) were emphasized by the documented movement of darters upstream beyond a replaced crossing. However, there can also be at least short-term negative impacts to darters and habitat downstream of crossings due to the transfer of fine sediments. Future surveys will allow us to evaluate the rate and degree of recovery as downstream reaches stabilize. Niangua Darter Monitoring Report 2010 Page 15

16 Literature Cited Anderson, D. R Model based inference in the life sciences. Springer, New York, New York. 184 pp. Arend, K. K Macrohabitat identification. Pages in M. B. Bain and N. J. Stevenson, editors. Aquatic habitat assessment: common methods. American Fisheries Society, Bethesda, Maryland. 216 pp. Bain, M. B Substrate. Pages in M. B. Bain and N. J. Stevenson, editors. Aquatic habitat assessment: common methods. American Fisheries Society, Bethesda, Maryland. 216 pp. Crawley, M. J The R book. John Wiley & Sons, Ltd, West Sussex. 942 pp. Cummins, K. W An evaluation of some techniques for the collection and analysis of benthic samples with special emphasis on lotic waters. American Midland Naturalist 67: Mattingly, H. T. and D. L. Galat Niangua Darter interim monitoring plan. Internal report to Niangua Darter Recovery Team and Missouri Department of Conservation. 32 pp. McCleary, C. M Spatial and temporal dynamics of habitat use and seasonal movements by Niangua Darters. M.S. Thesis. Missouri State University. 54 pp. Pflieger, W. F Distribution, status, and life history of the Niangua Darter, Etheostoma nianguae. Missouri Department of Conservation Aquatic Series No. 16. Jefferson City, Missouri. 25 pp. Pinheiro, J. C. and D. M. Bates Mixed-effects models in S and S-Plus. Springer-Verlag, New York. 528 pp. White, G. C., D. R. Anderson, K. P. Burnham, and D. L. Otis Capture-recapture and removal methods for sampling closed populations. Los Alamos National Laboratory Report. LA NERP, Los Alamos, New Mexico. 235 pp. Niangua Darter Monitoring Report 2010 Page 16

17 Table 1. Annual monitoring site locations by watershed, county, and legal description. Watershed/ Site County Township (N) Range (W) Section Little Niangua River LNR000_00 Camden LNR020 Hickory LNR025 Hickory LNR030_00 Hickory LNR040 Hickory LNR050 Camden LNR060_00 Hickory Maries River MAR000 Osage MAR020 Osage MAR040 Osage MAR050_00 Osage MAR060 Osage MAR070 Osage MAR080 Osage Niangua River NIR000 Dallas NIR030 Dallas NIR060_00 Dallas NIR070 Dallas NIR080 Dallas Pomme de Terre PDT000 Polk PDT030 Polk PDT040 Greene PDT050 Greene PDT060 Greene PDT090 Polk Tavern Creek TAC020 Miller TAC031 Miller TAC040 Miller TAC070 Miller TAC080 Miller TAC100 Miller Niangua Darter Monitoring Report 2010 Page 17

18 Table 2. List of sites monitored during 2010 to evaluate road crossing improvement projects including relevant watershed (italics), site name, road name, approximate date of crossing replacement, and analysis years before (PRE) and after (POST) road crossing replacement. Watershed, Site Road (Crossing) Name Replaced PRE year(s) POST years Little Niangua River BANNISTER00 Kolb Hollow Rd fall BANNISTER01 (Bannister Ford) GREENS00 Green Ford Rd fall ,2010 GREENS01 (Greens Ford) GRISWALD00 Green Ridge Dr fall ,2010 GRISWALD01 (Griswald Ford) LAKOTA00 Lakota Rd over Thomas Creek fall LAKOTA01 LNR000_00 Bannister Hollow Rd fall ,2010 LNR000_01 (Howards Ford) LNR030_00 Hickory Co Rd 96 spring , LNR030_01 (Muleshoe CA) LNR060_00 Hickory Co Rd 200 fall LNR060_01 (Erikson Slab) SCHOOLRD00 School Rd fall SCHOOLRD01 Maries River MAR050_00 Osage Co Rd 521 Expected ,2010 MAR050_01 (Sestak Slab) Niangua River NIR060_00 Steelman Rd fall NIR060_01 (Big John CA) WILLIAMS00 Benton Branch Rd fall ,2010 WILLIAMS01 (Williams Ford) Tavern Creek BARREN00 Sequoia Rd over Barren Fork fall BARREN01 TAVERN00 Tavern Creek Rd fall TAVERN01 WATKINS00 Watkins Ford Rd fall WATKINS01 Niangua Darter Monitoring Report 2010 Page 18

19 Table 3. Numbers of Niangua Darters by size class (Small, Medium, Large) observed during single-pass or the first pass of surveys in monitoring sites during 2002 to Year/Size class Watershed Site S M L S M L S M L S M L S M L S M L S M L S M L S M L Little Niangua LNR000_ LNR LNR LNR030_ LNR LNR LNR060_ Total Maries MAR MAR MAR MAR050_ MAR MAR MAR Total Niangua NIR NIR NIR060_ NIR NIR Total Pomme de Terre PDT PDT PDT PDT PDT PDT Total Niangua Darter Monitoring Report 2010 Page 19

20 Table 3 continued. Year/Size class Watershed Site S M L S M L S M L S M L S M L S M L S M L S M L S M L Tavern TAC TAC TAC TAC TAC TAC Total Grand Total Year Total Niangua Darter Monitoring Report 2010 Page 20

21 Table 4. Numbers of adult (medium + large)-sized Niangua Darters observed during single-pass or the first pass of surveys in monitoring sites during 2002 to Watershed Year Site Little Niangua LNR000_ LNR LNR LNR030_ LNR LNR LNR060_ Total Maries MAR MAR MAR MAR050_ MAR MAR MAR Total Niangua NIR NIR NIR060_ NIR NIR Total Pomme de Terre PDT PDT PDT PDT PDT PDT Total Niangua Darter Monitoring Report 2010 Page 21

22 Table 4 continued. Watershed Year Site Tavern TAC TAC TAC TAC TAC TAC Total Grand Total Niangua Darter Monitoring Report 2010 Page 22

23 Table 5. Trend analysis of the number of Niangua Darter adults per 100 m during 2002 to Shown for each watershed is a comparison of the best linear mixed model with a year effect and the model without a year effect included (the model with year that did not account for autocorrelation and the less suitable autocorrelation model are not shown). Model details indicate the autocorrelation model that was used (none, AR1 = first order autoregressive, ARMA = autoregressive moving average), number of model parameters (K), -2*log-likelihood or deviance (-2l), Akaike s information criterion corrected for small sample size (AICc), the difference between the AICc value of the model in question and the model with the lowest AICc or best model (Δ i ), the Akaike weight or model probability (w i ), evidence ratio that compares the best model to the alternate model (w i /w j = E i,j ), parameter estimate that would equal the intercept if no year effect or slope if a year effect was included (Par), 90% 1-sided confidence interval on the parameter estimate (CI), degrees of freedom (df), and sample size (n). Watershed Model K -2l AICc Δ i w i E i,j Par CI df n Little Niangua site,year AR site Maries site,year AR site Niangua site site,year ARMA Pomme de Terre site,year AR site Tavern site site,year Niangua Darter Monitoring Report 2010 Page 23

24 Table 6. Number of monitoring sites occupied by Niangua Darters / total number of sites (top row) and percentage of sites occupied (bottom row) for watersheds surveyed during 2002 to Also shown are the means (SE) of the number of sites and proportion of sites occupied across years. Watershed Mean (SE) Little Niangua 7/7 7/7 6/7 7/7 7/7 7/7 7/7 7/7 5/6 6.7(0.2) (2) Maries 5/7 3/7 3/7 5/7 4/7 3/7 6/7 7/7 6/7 4.7(0.5) (7) Niangua 0/5 0/5 2/5 1/5 2/5 3/5 1/5 1/5 2/5 1.3(0.3) (7) Pomme de Terre 2/6 2/6 4/6 2/6 5/6 3/6 5/6 4/6 5/5 3.6(0.4) (9) Tavern 4/5 4/6 4/6 4/5 5/5 6/6 4/6 6/6 3/6 4.4(0.3) (6) Total 18/30 16/31 19/31 19/30 23/30 22/31 23/31 25/31 21/ (1.0) (3) Year Niangua Darter Monitoring Report 2010 Page 24

25 Table 7. Number of habitat patches occupied by Niangua Darters / total number of patches (top row) and percentage of patches occupied (bottom row) for watersheds with monitoring sites surveyed during 2002 to Also shown are the means (SE) of the number of patches occupied, total number of patches, and percentage of patches occupied across years. Year Watershed Mean (SE) Little Niangua 12/25 17/34 21/28 37/60 22/42 32/61 22/49 20/50 32/ (2.7)/46.3(5.1) (3) Maries 8/22 10/26 6/22 16/41 7/38 5/50 20/42 22/56 7/ (2.1)/41.3(5.8) (5) Niangua 0/39 0/15 2/12 1/21 3/29 5/27 1/31 1/38 2/49 1.7(0.5)/29.0(4.0) (2) Pomme de Terre 2/42 2/27 6/26 3/34 10/42 6/45 17/47 13/60 13/62 8.0(1.8)/42.8(4.2) (3) Tavern 6/18 5/26 8/23 9/26 10/28 13/46 10/33 16/50 3/67 8.8(1.3)/35.2(5.3) (3) Total 28/146 34/128 43/111 66/182 52/179 61/229 70/202 72/254 57/ (5.2)/194.7(22.0) (2) Niangua Darter Monitoring Report 2010 Page 25

26 Table 8. Population estimates and mean probabilities of capture for monitoring sites where removal methods were used to estimate numbers of adult-sized Niangua Darters during 2009 and Standard errors are in parentheses and overall estimates for each watershed are in bold. Watershed (SE) Mean (SE) Site Little Niangua 159(8.4) 118(3.4) 0.68(0.05) 0.70(0.07) LNR000_00 127(8.3) 62(2.7) 0.65(0.06) 0.60(0.07) LNR020 3(0.0) 3(0.0) LNR025 21(0.4) 20(0.5) 0.82(0.03) 0.94(0.06) LNR030_00 3(1.2) 10(1.1) 0.33(0.00) 0.75(0.00) LNR LNR050 1(0.0) 23(1.7) 0.46(0.00) LNR060_00 4(0.7) (0.00) Maries 50(2.7) 18(1.3) 0.69(0.06) 0.71(0.29) MAR000 1(0.0) 0 MAR020 5(0.8) (0.00) MAR040 4(0.7) 4(0.0) 0.74(0.00) 1.00(0.00) MAR050_00 12(0.4) 1(0.0) 0.78(0.02) MAR (0.0) MAR070 22(2.1) 1(0.0) 0.71(0.10) MAR080 6(1.2) 11(1.3) 0.33(0.00) 0.42(0.00) Niangua 3(1.5) 1(0.0) 0.50(0.00) NIR000 1(0.0) NIR NIR060_00 3(1.5) (0.00) NIR NIR Pomme de Terre 92(9.4) 30(0.7) 0.43(0.05) 0.50(0.00) PDT000 10(2.3) 14(0.7) 0.39(0.06) 0.50(0.00) PDT030 1(0.0) 2(0.0) PDT (0.0) PDT060 6(1.9) 8(0.0) 0.42(0.00) PDT090 75(8.9) 5(0.0) 0.45(0.07) Tavern 23(2.4) 3(0.0) 0.46(0.08) TAC020 7(1.7) (0.00) TAC031 8(0.7) 1(0.0) 0.67(0.00) TAC040 4(1.5) (0.00) TAC (0.0) TAC080 2(0.0) 0 TAC100 2(0.0) 0 Niangua Darter Monitoring Report 2010 Page 26

27 Table 9. Mean Niangua Darter population densities (# adults/100 m (SE)) and detection probabilities (mean (SE)) by habitat patch type in each watershed where removal population estimates were performed during 2009 and 2010 (includes standard and road crossing monitoring sites). Watershed Habitat type Little Niangua Maries Niangua Pomme de Terre Tavern Population density Edge 7.4(1.8) 1.2(0.5) 0.1(0.1) 1.4(0.9) 0.4(0.4) Glide 5.6(1.1) 1.1(0.5) 0.0(0.0) 3.1(2.2) 2.2(1.3) Riffle 3.4(0.7) 1.0(0.4) 0.0(0.0) 0.5(0.2) 0.7(0.3) Run 4.9(1.4) 0.7(0.4) 0.1(0.1) 5.0(0.0) 0.7(0.5) Shallow pool 1.4(0.8) 0.0(0.0) 2.2(0.0) 0.8(0.5) 1.4(1.3) Detection probability Edge 0.61(0.06) 0.67(0.13) 0.54(0.21) 0.33(0.00) Glide 0.56(0.07) 0.69(0.20) 0.37(0.04) 0.50(0.07) Riffle 0.63(0.08) 0.73(0.04) 0.50(0.00) 0.50(0.10) Run 0.63(0.05) 0.65(0.22) 0.50(0.00) 0.42(0.05) 0.54(0.00) Shallow pool 1.00(0.00) 0.71(0.00) Niangua Darter Monitoring Report 2010 Page 27

28 Table 10. Sorensen distances (degree of disassociation, averaged by year ± SE) between Niangua Darter and other darter species based on presence/absence in habitat patches during 2002 to Species Sorensen Distance Ozark logperch 0.48 ± 0.03 Greenside darter 0.54 ± 0.02 Banded darter 0.55 ± 0.03 Orangethroat darter 0.57 ± 0.02 Rainbow darter 0.57 ± 0.02 Missouri saddled darter 0.69 ± 0.04 Fantail darter 0.74 ± 0.03 Stippled darter 0.84 ± 0.02 Bluestripe darter 0.97 ± 0.01 Johnny darter 0.97 ± 0.01 Niangua Darter Monitoring Report 2010 Page 28

29 Table 11. Numbers of Niangua Darters by size class (Small, Medium, Large) observed during singlepass or the first pass of surveys in sites associated with low water crossing improvements during 2002 to Bold numbers indicate data collected post-improvement of a low water crossing. Year/Size class Watershed Site S M L S M L S M L S M L S M L S M L S M L S M L S M L Little Niangua BANNISTER BANNISTER GREENS GREENS GRISWALD GRISWALD LAKOTA LAKOTA LNR000_ LNR000_ LNR030_ LNR030_ LNR060_ LNR060_ SCHOOLRD SCHOOLRD Maries MAR050_ MAR050_ Niangua NIR060_ NIR060_ WILLIAMS WILLIAMS Tavern BARREN BARREN MASSMAN MASSMAN TAVERN TAVERN WATKINS WATKINS Niangua Darter Monitoring Report 2010 Page 29

30 Table 12. Numbers of adult (medium + large)-sized Niangua Darters observed during single-pass or the first pass of surveys in sites associated with low water crossing improvements during 2002 to Bold numbers indicate data collected post-improvement of a low water crossing. Also shown are the pre- and post-improvement means (SE) calculated when both upstream and downstream sites were surveyed and percent change (after before). Percent change could not be calculated if PRE count = 0, therefore + indicates increase. Watershed Year Mean (SE) Change Site PRE POST % Little Niangua BANNISTER BANNISTER GREENS (8.5) 131 GREENS (0.5) -19 GRISWALD (0.5) 425 GRISWALD (0.5) 250 LAKOTA (1.0) + LAKOTA (0.6) + LNR000_ (30) -7 LNR000_ (3.5) + LNR030_ (3.3) -38 LNR030_ (4.6) 680 LNR060_ (3.9) -85 LNR060_ (2.8) 43 SCHOOLRD SCHOOLRD Maries MAR050_ MAR050_ Niangua NIR060_ (1) + NIR060_ (0.7) + WILLIAMS WILLIAMS Tavern BARREN (9.0) 9-44 BARREN (0.5) 1-33 MASSMAN (0.3) -75 MASSMAN TAVERN TAVERN WATKINS WATKINS Niangua Darter Monitoring Report 2010 Page 30

31 Table 13. Population estimate, standard error of the estimate, mean probability of capture, and standard error of the mean for sites associated with low water crossing improvements where removal methods were used to estimate numbers of adult-sized Niangua Darters during Watershed (SE) Mean Site Little Niangua BANNISTER00 65(5.7) 24(2.9) 0.45(0.12) 0.52(0.00) BANNISTER01 34(2.1) 15(5.0) 0.57(0.10) 0.86(0.15) GREENS00 18(2.4) 28(0.6) 0.41(0.05) 0.80(0.00) GREENS01 41(8.3) 16(0.9) 0.40(0.00) 0.90(0.00) GRISWALD00 31(6.5) 11(0.0) 0.37(0.11) GRISWALD01 4(0.0) 3(0.0) LAKOTA00 2(0.0) - LAKOTA01 3(1.2) (0.00) LNR000_00 127(8.3) 62(2.7) 0.65(0.06) 0.60(0.07) LNR000_01 49(4.3) 24(2.0) 0.70(0.15) 0.53(0.00) LNR030_00 3(1.2) 10(1.1) 0.33(0.00) 0.75(0.00) LNR030_01 71(22.2) (0.10) LNR060_00 4(0.7) (0.00) LNR060_01 11(0.4) 2(0.0) 0.91(0.00) SCHOOLRD00 0 SCHOOLRD01 0 Maries MAR050_00 12(0.4) 1(0.0) 0.78(0.02) MAR050_ Niangua NIR060_00 3(1.5) (0.00) NIR060_ WILLIAMS WILLIAMS01 1(1.0) 0 Tavern BARREN00 47(5.2) 13(0.6) 0.43(0.03) 0.71(0.00) BARREN01 2(0.0) 1(0.0) MASSMAN MASSMAN TAVERN00 3(0.0) TAVERN01 0 WATKINS00 16(2.1) 0.54(0.00) WATKINS01 0 Niangua Darter Monitoring Report 2010 Page 31

32 Table 14. Percentage of habitat patches occupied by Niangua Darters in sites associated with low water crossing improvements during Bold numbers indicate data collected postimprovement of a low water crossing. Also shown are pre- and post-improvement means (SE) calculated for years when both upstream and downstream sites were surveyed and the amount of change (after before). Watershed Year Mean (SE Change Site PRE POST Little Niangua BANNISTER BANNISTER GREENS (7) 14 GREENS (0) 0 GRISWALD (0) 75 GRISWALD (0) 33 LAKOTA (5) 15 LAKOTA (7) 14 LNR000_ (5) -4 LNR000_ (11) 56 LNR030_ (9) 57(7) -2 LNR030_ (4) 67(16) 0 LNR060_ (17) -60 LNR060_ (5) 3 SCHOOLRD00 0 SCHOOLRD01 0 Maries MAR050_ (24) MAR050_ Niangua NIR060_ (8) 8(8) 0 NIR060_ (22) 22 WILLIAMS WILLIAMS Tavern BARREN (3) BARREN (8) MASSMAN (3) -8 MASSMAN TAVERN TAVERN WATKINS WATKINS Niangua Darter Monitoring Report 2010 Page 32

33 Table 15. Mean length (SE) of non-pool habitat (pool edge and deep pool excluded) and mean darter species richness (SE) before and after road crossing improvements during calculated for years when both upstream and downstream sites were surveyed including the amount of change (after-before). Non-pool Habitat (m) Darter Species Richness Before After Change Before After Change Site mean (SE) mean (SE) % mean (SE) mean (SE) Little Niangua BANNISTER BANNISTER GREENS (23) (0.0) 1.0 GREENS (1.0) 3.0 GRISWALD (53) (0.5) 1.5 GRISWALD (60) (1.0) 4.0 LAKOTA (19) (0.4) 0.2 LAKOTA (24) (0.3) 2.0 LNR000_ (47) (0.5) -1.5 LNR000_ (56) (0.0) 6.0 LNR030_00 255(121) 326(40) (0.5) 7.3(0.3) -0.1 LNR030_01 107(30) 178(33) (0.5) 6.3(0.6) -0.3 LNR060_ (77) (0.6) -1.0 LNR060_ (25) (0.6) 1.0 SCHOOLRD SCHOOLRD Maries MAR050_00 280(29) 8.5(0.5) MAR050_01 162(0) 5.0(0.0) Niangua NIR060_00 180(34) 196(14) 9 5.7(2) 6.7(0.7) 1.0 NIR060_01 215(15) 357(39) (1.9) 6.7(0.9) 1.0 WILLIAMS00 106(14) 7.0(2.0) WILLIAMS01 70(8) 6.5(0.5) Tavern BARREN00 422(30) (0) BARREN01 437(49) (0.5) MASSMAN (25) (0.5) -0.3 MASSMAN (24) (0.3) 2.5 TAVERN TAVERN WATKINS WATKINS Niangua Darter Monitoring Report 2010 Page 33

34 Population Monitoring Site Low Water Crossing Site Niangua Darter Range Figure 1. Niangua Darter annual population monitoring sites and low water crossing improvement monitoring sites sampled during Niangua Darter Monitoring Report 2010 Page 34