Shane M. Welch

Semi-quantitative Methods for Crayfish Sampling: Sex, Size, and Habitat Bias

Abstract We evaluated the effectiveness of four sampling methods for freshwater crayfish in five aquatic habitat types in Congaree National Park, South Carolina, USA. Electrofishing was the most successful technique in terms of the diversity of species collected, the number of individuals collected, and the widest range of sizes collected. Seine netting was the next most successful method. Baited minnow traps were biased towards form I males and larger individuals, while dip netting was biased towards smaller individuals. The relative success of techniques depended somewhat upon species. For two stream dwelling species, Procambarus acutus and P. chacei, electrofishing collected significantly more individuals than any other technique. For P. troglodytes, the most abundant species and a habitat generalist, electrofishing was superior to dip netting in some habitats, but did not significantly differ from traps or seine netting. For Fallicambarus fodiens, no significant differences among the effectiveness of any sampling methods were detected.

The reproductive response of an endemic bunchgrass indicates historical timing of a keystone process

Restoration of the Pinus palustris (longleaf pine)-wiregrass ecosystem of the southeastern United States requires information on reference conditions such as the historical fire regime. Aristida beyrichiana (wiregrass), a keystone perennial bunchgrass, was historically widespread throughout the southeast, but its dependence upon growing season fires for sexual reproduction hastened its decline in the face of decades of human fire suppression. The reproductive response of wiregrass is described by patterns of meristem allocation between competing life history strategies (i.e., vegetative growth vs. sexual reproduction). The temporal link between fire and flowering indicates this allocation was optimized to the historical fire regime through selection. In this study, we used the observed allocation of wiregrass reproductive effort to sexual reproduction as the response variable to examine reproductive response to fire season, using plant size as a covariate. Sexual reproduction was positively associated with plant size. Plants burned during early summer (May–June) produced a greater proportion of inflorescences than did those burned in early spring (March–April) or in late summer (August). Using state records of natural (lightning-ignited) and anthropogenic (human-ignited) fires from historical (1933–1946) and contemporary (1998–2010) periods we found that the distribution of maximum wiregrass reproductive output most closely reflected the distribution of historical fires with natural ignition sources. Moreover, while the monthly distributions of historical and contemporary fires were different for anthropogenic ignitions, they did not differ for fires with natural ignitions. Our predictions of peak allocation based upon the biology of wiregrass provide strong support for the use of wiregrass as an indicator of the historical fire season (early summer). Efforts to restore the longleaf pine ecosystem should therefore consider the biological response of wiregrass in planning prescribed fires.

Seasonal Variation and Ecological Effects of Camp Shelby Burrowing Crayfish (Fallicambarus Gordoni) Burrows

ABSTRACT Foam casts and burrow excavations were used to examine Fallicambarus gordoni burrow occupancy rates, seasonal variation in burrow morphology, correlation between crayfish abundance and burrow abundance and potential ecological effects of burrowing through soil disturbance and the creation of fossorial habitat. Burrow occupancy rates were high (75%) and consistent between active and inactive seasons, although several burrow metrics differed significantly between seasons. Crayfish abundance was strongly correlated with burrow abundance. Estimates of annual soil disturbance (82 metric tons/ha/y) and fossorial habitat created (29–49 km/ha) suggest F. gordoni serves important ecological functions within the greater habitat.

Effects of parental radiation exposure on developmental instability in grasshoppers

Mutagenic and epigenetic effects of environmental stressors and their transgenerational consequences are of interest to evolutionary biologists because they can amplify natural genetic variation. We studied the effect of parental exposure to radioactive contamination on offspring development in lesser marsh grasshopper Chorthippus albomarginatus. We used a geometric morphometric approach to measure fluctuating asymmetry (FA), wing shape and wing size. We measured time to sexual maturity to check whether parental exposure to radiation influenced offspring developmental trajectory and tested effects of radiation on hatching success and parental fecundity. Wings were larger in early maturing individuals born to parents from high radiation sites compared to early maturing individuals from low radiation sites. As time to sexual maturity increased, wing size decreased but more sharply in individuals from high radiation sites. Radiation exposure did not significantly affect FA or shape in wings nor did it significantly affect hatching success and fecundity. Overall, parental radiation exposure can adversely affect offspring development and fitness depending on developmental trajectories although the cause of this effect remains unclear. We suggest more direct measures of fitness and the inclusion of replication in future studies to help further our understanding of the relationship between developmental instability, fitness and environmental stress.

Tree rings reveal extent of exposure to ionizing radiation in Scots pine Pinus sylvestris

Tree growth has been hypothesized to provide a reliable indicator of the state of the external environment. Elevated levels of background ionizing radiation may impair growth trajectories of trees by reducing the annual growth. Such effects of radiation may depend on the individual phenotype and interact with other environmental factors such as temperature and drought. We used standardized growth rates of 105 Scots pine Pinus sylvestris located near Chernobyl, Ukraine, varying in the level of background radiation by almost a factor 700. Mean growth rate was severely depressed and more variable in 1987–1989 and several other subsequent years, following the nuclear accident in April 1986 compared to the situation before 1986. The higher frequency of years with poor growth after 1986 was not caused by elevated temperature, drought or their interactions with background radiation. Elevated temperatures suppressed individual growth rates in particular years. Finally, the negative effects of radioactive contaminants were particularly pronounced in smaller trees. These findings suggest that radiation has suppressed growth rates of pines in Chernobyl, and that radiation interacts with other environmental factors and phenotypic traits of plants to influence their growth trajectories in complex ways.

The use of Citizen Scientists to Record and Map 13-Year Periodical Cicadas (Hemiptera: Cicadidae: Magicicada) in South Carolina

Citizen science is the process in which citizens are involved in science as researchers (Carr 2004). This can range from involvement in a collaborative effort from academic and government agencies in the assessment of a common environmental (community) concern to the management of common natural resources (Conrad & Hilchey 2011). Traditionally, the use of citizen scientists involved the collection of data on species detection and habitat. This is due to the difficulty of a single monitoring agency in obtaining accurate data for proper population assessment (Conrad & Hilchey 2011). Increasing concern regarding the effect of climate change and land development on biodiversity has raised interest in assessing evolutionary responses of plants and animals, particularly for species that are absent in some years but abundant in others (Heliovaara et al. 1994; Lepetz et al. 2009). Brood XIX of periodical cicadas (Hemiptera: Cicadidae: Magicicada) consists of 3 species (M. tredecassini, M. tredecim, M. tredecula) that emerge synchronously every 13 years. Historically, Brood XIX has been recorded to span along the United States east coast from Maryland to Georgia and in the Midwest from Iowa to Oklahoma (Simon 1988). Males and females emerge from the ground close to their host tree and eclose into their adult form. Adults are approximately 4 cm long with red eyes, orange-veined wings and black bodies (Fig. 1). They live above ground for approximately 4-6 wk. The males produce species-specific calls that attract both sexes in the forest canopy resulting in large aggregations in areas of high population densities. After mating, females disperse to nearby trees and lay eggs into slits cut into the branches. Nymphs hatch from eggs after 6-8 wk and drop to the ground where they feed on root xylem fluids for another 13 yr (White & Strehl 1978; Williams & Simon 1995). In South Carolina, the 1985 emergence began around 21 Apr in Abbeville and Saluda counties. Cold weather delayed the emergence in 1998 resulting in fewer sightings. Based on anecdotal and general accounts, periodical cicadas were suspected to emerge in approximately 25 South Carolina counties (Gorsuch 1998). The anticipated 2011 Brood XIX emergence provided a unique opportunity to apply the use of citizen scientists in obtaining a more accurate assessment of the species range in South Carolina. The aim of the project was to use voluntary internet reports of sightings to examine spatial and temporal patterns of periodical cicada emergence and document citizen’s impressions of the Brood XIX emergence. Three South Carolina state institutions established internet sites for citizens to report sightings (Clemson University: http://clemsoncicada.word-

Conservation Of Imperiled Crayfish – Distocambarus (fitzcambarus) youngineri Hobbs And Carlson 1985 (Decapoda: Cambaridae)

Conservation status.—Endangered (Taylor et al., 2007), critically imperiled in South Carolina and globally (S1, G1; South Carolina Comprehensive Wildlife Conservation Strategy 2005-2010, [SC CWCS] 2005). Based on the species’ limited distribution (, 20,000 km) and its observed decline at population sites (Eversole, 1995a, b, unpublished data) D. youngineri has been classified as vulnerable, VU B1b (i, iv), following IUCN (2001).

Light Bait Improves Capture Success of Aquatic Funnel-Trap Sampling for Larval Amphibians

Abstract Aquatic funnel traps are a non-destructive means of surveying amphibians in lentic habitats, particularly as compared to dip-net surveys that disturb aquatic vegetation and the substrate, and affect the water column through increased turbidity. The objective of this study was to examine the utility of glow stick-baited aquatic funnel traps for larval amphibians, with a particular emphasis on ambystomatid larvae. We sampled 12 isolated ponds in the Mid-Atlantic Coastal Plain of South Carolina between April and June 2010 and used detection/non-detection capture data to model the probability of capturing larval amphibians in baited and un-baited funnel traps. Further, we used count data (captures per trap) to examine whether glow stick-baited traps captured more amphibian larvae than un-baited traps. We captured four Ambystoma species (A. mabeei, A. opacum, A. talpoideum, and A. tigrinum) and tadpoles from the families Bufonidae, Ranidae, and Hylidae in light-baited funnel traps. Captures of both Ambystoma larvae and tadpoles were positively associated with light-baited traps, and we were 8.8 times more likely to capture Ambystoma larvae and 5.7 times more likely to capture tadpoles in glow stick-baited traps as compared to un-baited traps. Our results indicate that glow sticks can greatly improve capture success of larval amphibians in funnel traps, and we recommend their use as an active sampling method that is unbiased by surveyor experience and skill-level.

Using Occupancy Models to Examine Human–Wildlife Interactions

Occupancy models provide a structural template for modeling spatial and temporal components of human–wildlife interactions in which outcomes are contingent on both human–wildlife co-occurrence and encounter probability. Because human–rattlesnake interactions are often contingent on post-encounter, human-initiated contact, we categorized these interactions into discrete components: co-occurrence of rattlesnakes and humans, and the probability that a human detects the rattlesnake. We used occupancy models to examine correlates of human–rattlesnake co-occurrence and assumed human–rattlesnake encounter probability was synonymous with detection probability. Occupancy (i.e., proportion of sites occupied) was associated with rattlesnake habitat preference, and encounter probability was influenced by air temperature. Our results indicate that covariates associated with rattlesnake activity (e.g., air temperature) were the best predictors of encounters. This article illustrates the use of occupancy models for identifying spatial and temporal drivers of human–wildlife interactions. Our results will aid management actions and policies that maximize human safety and rattlesnake conservation.

Environmental Effects on Southern Two-Lined Salamander (Eurycea cirrigera) Nest-Site Selection

Nest-site selection is a critical process in the life history of amphibians, directly influencing offspring survival and parental fitness. When and where an amphibian chooses to nest is strongly influenced by a range of environmental cues. In this study, we evaluated nest-site selection of the Southern Two-lined salamander, Eurycea cirrigera, in relation to a range of environmental conditions. We monitored nesting E. cirrigera under coverboards at two seepage wetlands in the South Carolina inner Coastal Plain during the breeding season of E. cirrigera. We examined nest-site selection by E. cirrigera at two scales (landscape scale and microhabitat scale) using logistic regression and AIC model selection. We found that E. cirrigera select nest sites using environmental cues across multiple spatial scales where females actively discriminate among nesting locations based on measures of temperature, hydrology, and water depth. Because amphibians are so sensitive to environmental change and variation, understanding the factors that influence key life history processes, particularly breeding phenology and oviposition site choice, are critical to the conservation of amphibian populations and their habitats.