Hayden T. Mattingly

Distributional Patterns of the Threatened Niangua Darter, Etheostoma nianguae, at Three Spatial Scales, with Implications for Species Conservation

Abstract The Niangua darter, Etheostoma nianguae, is a threatened stream fish endemic to the Osage River basin in south-central Missouri. We studied the darters distributional patterns at three spatial scales (stream, reach, and microhabitat) to assist ongoing conservation efforts. Darter presence-absence as a function of one or more habitat variables was modeled with logistic regression at each scale. The most important predictors of presence-absence were stream link magnitude, mean confluence difference (CD), reach length or gradient, streambed elevation, bank erosion index, water depth, and substrate mean particle size. At the stream scale, darters were present in larger streams (e.g., fifth order) with small CDs. A relatively small CD, for example, described the convergence of two streams of roughly equal size in the drainage basin, whereas a relatively large CD indicated a substantial difference at a confluence. We propose that the CD metric represents a large-scale zoogeographic barrier to E. nianguae, excluding this species from any tributary stream that flows into a receiving stream that is three or more stream orders larger than the tributary. Within one occupied stream, the Little Niangua River, darters were found disproportionately in reaches (1) located in the mid- to lower sections of the stream (elevations 230–250 m above sea level), (2) with riffles spaced 40–80 m apart or with gradients of 2–4 m × km−1, and (3) with relatively uneroded banks. Within occupied reaches, they were commonly located in microhabitats 20–40 cm deep with substrate particles averaging 30–50 mm in diameter. Multivariate model precision ranged from 29–57% within single scales. The models can be used to guide conservation and recovery efforts by ranking sites in the Osage basin based on their relative suitability for E. nianguae.

Efficacy of Internal PIT Tagging of Small-Bodied Crayfish for Ecological Study

Abstract Recent studies have demonstrated the feasibility of using passive integrated transponder (PIT) tags for tracking crayfish spatiotemporally in streams. PIT tags can be inserted internally for long-term tracking, assuming low tagging mortality, or attached externally for shorter-term tracking until the individual molts. To date, the practical use of internal cephalothorax tagging has been limited to individuals >30 mm carapace length (CL). The efficacy of internal tagging for small-bodied crayfish species or juveniles of large-bodied species remains poorly understood. We conducted studies with the small-bodied Orconectes compressus (Slender Crayfish) to assess whether internal placement of small PIT tags (8.5 mm long, 2.12 mm diameter) was a viable methodology for future ecological work. In the field, we tagged 63 crayfish and monitored them with a portable transceiver system for 1.5 weeks. In the laboratory, we tagged 21 crayfish and maintained 21 control crayfish for 12 weeks. Crayfish averaged 18 mm CL (n = 84). In the field, there was high initial (14 of 63) and delayed (16 of 63) mortality. We also observed initial (3 of 21) and delayed (11 of 21) mortality in the laboratory within the first 10 days. Smaller individuals had higher mortality rates in both studies. We constructed logistic regression models with field (P = 0.005) and laboratory data (P = 0.027) to show the likelihood of tagging mortality as a function of carapace length. Our results suggest that internal PIT tagging could induce undesirably high mortality in crayfish <22 mm CL for most ecological study objectives.

Reproductive Ecology and Captive Breeding of the Threatened Niangua Darter Etheostoma nianguae

Abstract The Niangua darter Etheostoma nianguae is a threatened stream fish endemic to the Osage River basin of Missouris Ozark uplands. We studied the darters reproductive behavior under natural conditions in the wild to assist recovery efforts. In addition, techniques for captive propagation were developed in the event that wild populations should suffer precipitous declines. Seven spawning events were witnessed by snorkelers in swift riffle areas at mean (± SD) water depths of 23 ± 5 cm, column current velocities of 83 ± 12 cm/s and focal current velocities of 43 ± 9 cm/s. This combination of depth and velocity was used only for spawning; darters were found at slower velocities and greater depths when not spawning during spring and at slower velocities during summer. Niangua darters in captivity spawned in 38 liter aquaria with fine uniform substrate and no current velocity, and larvae were reared to the juvenile stage. Time from fertilization to hatching was 10–11 d at 16 C. Larvae swam up 3 d after hatching and remained in the water column 31–33 d before returning to the substrate. We suggest a spawning protocol that includes capturing wild males and females during April, isolating spawning pairs in 38 liter aquaria with fine substrate and maintaining low light levels during hatching. Young can be reared on brine shrimp nauplii, zooplankton and, later, frozen adult brine shrimp. A chronology of Niangua darter reproductive and early life history events is provided.

Population Status and Nesting Biology of the Rare Barrens Darter, Etheostoma forbesi

Abstract The Barrens darter Etheostoma (Catonotus) forbesi (Teleostei: Percidae) is a rare stream fish endemic to the upper Caney Fork River system in the Barrens Plateau region of middle Tennessee. We studied the darters population characteristics and selected aspects of its nesting biology at 10 sites surveyed during April 2004. In our survey, we caught a total of 75 Barrens darters at a rate of 21 individuals per hour of backpack-electrofishing effort. At least one male Barrens darter was present at six of the 10 sites. Females outnumbered males by a ratio of 1.4 to 1. Total lengths ranged 44–97 mm, averaging 62 mm for females and 78 mm for males. The number of Barrens darters seen in the present survey was similar to a 1994 survey. However, both surveys reveal a species in need of conservation, with low abundance at most known sites within its limited geographic range. We found 20 Barrens darter nests located on the flat undersides of cobbles with a mean length, width and thickness of 17 × 13 × 5 cm. Nests in one stream, Duke Creek, were located at a mean water depth of 22 cm, column current velocity of 15 cm/s and bottom velocity of 7 cm/s. Stream channel widths averaged 3.5 m at nest rock locations. Nests contained a mean number of 463 eggs (range 69–976) arranged in a monolayer. Male size and the number of eggs per nest were positively correlated with nest rock size for eight nests where we captured the attending guardian male; however, egg number was not correlated with rock size for all nests in the study.

LIFE HISTORIES OF TWO POPULATIONS OF THE IMPERILED CRAYFISH ORCONECTES (PROCERICAMBARUS) WILLIAMSI (DECAPODA: CAMBARIDAE) IN SOUTHWESTERN MISSOURI, U.S.A.

The imperiled Williams’ Crayfish, Orconectes williamsi Fitzpatrick, 1966 is endemic to southwestern Missouri and northwestern Arkansas, U.S.A., an area experiencing rapid urbanization and other land use changes. Populations of O. williamsi in two small streams were studied for 26 months to describe annual reproductive cycles, and gather information about fecundity, sex ratio, size at maturity, size-class structure, and growth. We captured a monthly average of more than 120 O. williamsi from each of the two study populations. The life history of O. williamsi appeared generally similar to what has been reported for several other stream-dwelling species of Orconectes. Breeding season occurred in mid to late autumn and perhaps into early winter. Egg brooding occurred during late winter and early spring, although it was difficult to locate females carrying eggs or hatchlings. Young of year first appeared in samples during May and June. We estimated that these populations of O. williamsi contained 3 or 4 size-classes; smaller O. williamsi grew faster than larger individuals and the mean specific growth rate was about 2% per day during summer. Life history information presented herein will be important if expected future conservation efforts are required.

Threatened fishes of the world: Etheostoma forbesi Page and Ceas, 1992 (Percidae)

Common name: Barrens darter (E). Conservation status: Endangered (Tennessee); Species ofManagement Concern (US Fish & Wildlife Service). Identification: One of ten species in the Etheostoma squmiceps complex within subgenus Catonotus (Page et al. 1992). D 8-9 spines, 14-15 rays; A 2 spines, 7–9 rays; P 11-12; LL 41–54 (25–45 pored). Females 59 mm, males 74 mm average SL. Females and non-breeding males have brown mottling on tan background, and are morphologically indistinguishable from other females and non-breeding members of the E. squamiceps complex. Breeding males distinguished from all species (except allopatric E. corona) by 14-15 dorsal rays and yellow-gold margin on second dorsal fin. Illustration by Matthew R. Thomas. Distribution: Endemic to Caney Fork River headwaters in central Tennessee. Found at 11 sites within nine streams in 1994 (Madison 1995) and six of ten sites resurveyed in 2004 (Hansen et al. 2006). Present known range is limited to <10 stream km. Abundance: Considered one of the rarest fishes in North America (Page et al. 1992). Only 93 and 75 individuals were observed in 1994 and 2004 surveys. Habitat and ecology: Inhabits small headwater streams with gravel and slabrock cobble substrates (Etnier and Starnes 1993). Preferred habitat availability is currently being studied. Reproduction: Spawning occurs in AprilMay (Madison 1995) with male-guarded eggs laid in a monolayer on the underside of slabrock cobble. Average egg cluster size 463 (range 69–976). Mean length, width, and thickness of nesting rocks 17, 13, and 5 cm (Hansen et al. 2006). Threats: Vulnerable due to limited distribution and small population size. Other potential threats include habitat degradation, limited availability of spawning habitat, and competition or hybridization with closely related E. crossopterum. Conservation recommendations: Due to its restricted distribution, small population size, and current threats, E. forbesi may warrant stronger legal protection (Page et al. 1992; Etnier 1997). Remarks: Landowner cooperation will play an essential role in conserving this rare fish. Environ Biol Fish (2010) 87:249–250 DOI 10.1007/s10641-010-9596-y

Population Densities of Two Rare Crayfishes, Cambarus obeyensis and Cambarus pristinus, on the Cumberland Plateau in Tennessee

Abstract Cambarus obeyensis (Obey Crayfish) and Cambarus pristinus (Pristine Crayfish) are species of conservation concern, but basic information needed by conservation managers is lacking. To provide a quantitative measure of abundance, we conducted a mark—recapture study at six 100-m reaches per species during May–August 2013. These sites were a subset that we selected from eighty-nine 100-m reaches surveyed during 2011–2013. We built regression models to predict crayfish abundance based on single-pass capture rates for the 12 mark—recapture sites and for all occupied sites identified during the 2011–2013 surveys. We also calculated site-level density and capture efficiency for each species. Cambarus pristinus occurred at significantly lower densities across a larger range than C. obeyensis. Capture efficiency for both species varied across sites, suggesting that monitoring programs should incorporate regular, quantitative estimates of density and capture efficiency. Our results indicate that both species merit ongoing conservation attention and that C. pristinus may represent a higher conservation priority than previously recognized.