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Incidental observations of aquatic exotic species may represent important early indicators of established populations. Herein we report ecologically significant observations of 2 exotic fish taxa in southern Alabama—Pterygoplichthys disjunctivus x pardalis (Amazon Sailfin Catfish) and Oreochromis niloticus (Nile Tilapia). Our observations establish the presence and confirm reproduction, respectively, of these species in the state.
Naturally occurring mixed species broods are uncommon but can occur due to nest parasitism, and in rare cases, due to usurpation. We report on a mixed brood resulting from a pair of Tree Swallows usurping a Carolina Chickadee nest. The chickadee nest was constructed in a nest box, and 1 egg was laid prior to usurpation. This egg, in addition to the clutch of swallow eggs, was incubated, hatched, and fed by the adult swallows. The chickadee nestling grew and appeared to be healthy at 6–7 days of age, but was approximately 50% smaller than its nest mates at that time. The chickadee died after 8 days, most likely due to starvation. The remaining Tree Swallow nestlings were reared to fledging by the adults.
Calymmaria persica (Hentz) is a rarely collected spider in the family Hahniidae (Araneae) previously known to occur primarily in the Appalachian Mountains. This note reports 2 new localities, each of which is a significant range extension for this species. One specimen was collected on Mount Magazine, AR, and is the first record west of the Mississippi River. The second locality is the Loessal Hills in north-central Mississippi and represents the first specimen collected in the region between southwestern Mississippi (Wilkinson County) and the Appalachian region of northern Alabama. An updated range map is included.
Spilogale putorius (Eastern Spotted Skunk) is an elusive species, and little is known about their natural history in the southeastern US. We used a game camera to observe a female Eastern Spotted Skunk in the southern Appalachians of Alabama carrying 6 different prey items to her den from February to August 2015. Half of the observations occurred while she had 2 dependent kits, suggesting she was provisioning them with food. Identified food items included 3 snakes, a small mammal, a fungal sporocarp, and an anuran.
Macrochelys temminckii (Alligator Snapping Turtle) was petitioned for federal listing as threatened under the Endangered Species Act in 2012 as a result of population declines attributable in part to harvest for human consumption. The species was listed as threatened in 1992 in Georgia, where all harvest of the species was closed. Because little is known about how Alligator Snapping Turtle populations respond to protection, we surveyed Georgia's Flint River, which had originally been surveyed in 1989, to assess whether abundance of Alligator Snapping Turtles increased following close of commercial harvest. Our survey, conducted in 2014 and 2015 yielded captures of 52 Alligator Snapping Turtles with an overall catch per unit effort (CPUE) of 0.09 turtles/trap-night, as compared to 62 captures and a CPUE of 0.08 turtles/trap-night in the 1989 survey. Although CPUE was similar between the two studies, we observed differences among the lower, middle, and upper reaches of the river; CPUE increased in the lower reach, decreased slightly in the middle reach, and remained the same in the upper reach of the Flint River. Mean size (carapace length) of Alligator Snapping Turtles did not differ between the 2 surveys, but in 2014–2015 we caught nearly twice as many immature (<40 cm carapace length) turtles as adult males and females, and the highest proportion of immature turtles was captured in the upper reach. Our findings suggest that the Alligator Snapping Turtle population in the Flint River has not increased despite 22 years of protection from commercial harvest. Recovery may be hampered by life-history characteristics of the species including delayed maturity and low reproductive output; however, we cannot rule out possible ongoing mortality of Alligator Snapping Turtles from illegal harvest or drowning on abandoned limb lines, as has been observed in other populations.
Gopher Tortoise (Gopherus polyphemus) burrows are used by more than 60 vertebrate species, but the frequency with which species use burrows and the extent to which other vertebrates use the mound of sand at the burrow entrance, called the burrow apron, has not been quantitatively assessed. Between 2 June and 9 October 2014, we monitored active and inactive adult Gopher Tortoise burrows with motion-triggered trail cameras to identify and enumerate vertebrate burrow visitors. We recorded 12,238 video clips during 2299 trap nights, of which 10,151 (83%) contained a Gopher Tortoise and 1732 (14%) contained other vertebrate species. We reduced multiple videos of a single burrow visitation to 1 observation, resulting in 929 observations of 14 vertebrate species (not including the Gopher Tortoise) using tortoise burrows and 34 species on burrow aprons. Mammals were the most commonly recorded taxa (54%), followed by birds (32%), amphibians (9%), and reptiles (5%). Active burrows were visited more frequently than inactive burrows across all taxa, and burrow aprons were used more frequently than the burrow tunnel. Although active and inactive Gopher Tortoise burrows provide refuge for some vertebrate species, active burrows may provide additional resources, such as increased prey for insectivorous species. More species were found to be present on burrow aprons than within burrows, indicating the apron may be an important microhabitat for species, including those not known to use burrows.
A year-long continuous pitfall trapping program in 8 habitats at the Savannah River Site on South Carolina's coastal plain yielded over 4200 individual Opiliones, and the resulting data set provides a fine-grained description of Opiliones faunistics, habitat distribution, and phenology in southeastern North America, where Opiliones biology has been neglected. The 9 species reported from the site include a new state record (Vonones sayi), a rarely reported species (Bishopella laciniosa), and a common species that was undescribed at the time of the study (Hadrobunus fusiformis). All species abundant enough to examine seem to be univoltine and to reproduce in the warm season (adults mostly present in autumn), but species varied greatly in seasonality and duration of the peak adult sample period and in their habitat distribution. Leiobunum bimaculatum preferred xeric sites, H. fusiformis was widely distributed across habitats, and the other species were generally more abundant in more mesic habitats. Richness estimation showed that the ground-accessible Opiliones fauna was adequately sampled by this pitfall regime.
The Guana Tolomato Matanzas National Estuarine Research Reserve (GTMNERR), located in Northeast Florida, serves as an ideal estuarine habitat for many economically and ecologically important species of fish and crabs. As climate change affects Florida ecosystems, the replacement of Spartina alterniflora (Smooth Cordgrass) marshes by northward-moving mangroves is possible. A change in the dominant vegetation has the potential to alter organic carbon inputs, which can lead to a shift in the primary and secondary consumers in the area. An assessment of the fish community is needed in the systems where the change from Smooth Cordgrass to mangrove is the most likely in order to determine which species and which breeding populations will be affected. We conducted a biodiversity survey over the course of 24 months to document the seasonal and spatial patterns in species richness, seasonal abundance, and size of species caught. From May 2013 to April 2015, we used a 15.24-m seine net to sample 8 sites within the GTMNERR. Comparable to many other estuaries, the catch per unit effort and species richness decreased in the colder winter months and rose through spring and summer. Temperature was the main factor that controlled the species assemblage, with some species recorded only during certain months of the year, while salinity was a minor parameter. Certain species were correlated with colder seasons, i.e., Leiostomus xanthurus (Spot) juveniles and Menidia spp. (silverside), or negatively correlated with other species, i.e., Spot and Fundulus similis (Longnose Killifish). Temperature and species interactions can be useful in tracking specific populations and the effects of anthropogenic influences in this system.
Tsuga canadensis (Eastern Hemlock) and T. caroliniana (Carolina Hemlock) are important components of western North Carolina forests. The invasive Adelges tsugae (Hemlock Woolly Adelgid [HWA]) was first reported in NC in 1995, and by 2007 the entire range of hemlock in the state was infested. An examination of the Forest Inventory and Analysis (FIA) program data for FIA Unit 4 (21 mountainous counties in western North Carolina), looking at remeasured trees for the time period 1999–2013, demonstrated that diameter net growth of hemlock decreased and mortality increased with increasing duration of HWA infestation. Hemlock trees in this study had a ∼50% chance of survival after 12 years of confirmed HWA infestation in the county where they occur, and growth of surviving trees was reduced by ∼50% over the same time period. This study demonstrates the utility of FIA data for examining effects of an introduced, invasive pest on tree growth and mortality over a relatively small area. Some advantages and limitations to our approach are discussed.
Fire-suppressed forests in Oak Mountain State Park (OMSP; Shelby County, AL) have undergone experimental prescribed burning as a means to restore the open canopy architecture and diverse understory characteristic of Pinus palustris (Longleaf Pine) communities. Populations of a ground-hunting spider, Ctenus hibernalis, in the forests of OMSP were studied in order to examine the effect of restoration efforts on populations of understory arthropods. Study sites included regions burned 1 year prior and 5 years prior, as well as a region that has experienced 2 decades of fire suppression. No individuals of C. hibernalis were found in the region burned 1 year prior. There was no significant difference in the total number of spiders in the fire-suppressed region and the region burned 5 years prior, although the body mass of the spiders in the region burned 5 years prior was significantly greater than those in the fire-suppressed region. These results suggest that increased resource availability related to prescribed burns leads to increased spider fitness.
Scincella lateralis (Little Brown Skink, hereafter Skink) are ubiquitous throughout the southeastern US and primarily nest in leaf litter on the forest floor. However, their presence in coastal marsh settings necessitates their use of alternate nesting habitats. We investigated Skink nesting ecology in Alligator mississippiensis (American Alligator) nests and Ondatra zibethicus (Muskrat) houses in an intermediate/brackish coastal marsh habitat at Rockefeller Wildlife Refuge in southwestern Louisiana. For our field studies, we found and collected Skink eggs from 16 June through 5 October, and hatched eggshells from 6 July through 5 October. We found Skink eggs/eggshells in 36 of 109 active American Alligator nests (33.0%), 19 of 36 inactive Alligator nests (52.8%), and 13 of 51 Muskrat houses (25.5%). Clutch size ranged from 1 to 5 eggs (average = 3.0). The mean depth of Skink eggs was 24.6 cm in American Alligator nests and 17.1 cm in Muskrat houses. Multiple clutches commonly occurred in a structure, indicating repeated use by a single female Skink or communal nesting. In one extreme case of communal nesting, we collected at least 932 Skink eggs and hatched eggshells from a single Alligator nest. Skink eggs that we measured weekly during a 30-day incubation period increased in length and width. Earliest hatch dates for laboratory-incubated Skink eggs occurred from 28 June through 3 July; the last Skink hatched on 14 October. We documented a hatch rate of 87.6%. Hatchlings (n = 806) had a mean total length of 5.01 cm (n = 23) and a mean snout—vent length of 2.02 cm (n = 18). Our study indicated that Skinks readily nest commensally and communally within coastal marsh Alligator nests and Muskrat houses.
This study examines the effect of beech bark disease (BBD) on Sus scrofa (European Wild Boar) rooting in high-elevation Beech gaps of Great Smoky Mountains National Park. In 2011, we sampled vegetative cover by stratum (canopy, shrub, herb) and European Wild Boar rooting extent in pre-existing fenced boar-exclosure plots and corresponding unfenced plots. We also used data from previous studies to compare frequencies of individual herbaceous species collected pre-BBD to those collected post-BBD. Our results indicate that mortality of Fagus grandifolia (American Beech) trees due to BBD and the consequent growth of a dense shrub-layer significantly reduced boar rooting in gaps within the Beech stands. We found that herbs were affected by both European Wild Boar and the dense shrub-cover following American Beech mortality; however, some plant species remained abundant, possibly because they were protected from detection within the shrubs.
Results obtained in studies of grassland myxomycetes (plasmodial slime molds or myxogastrids), based on the species appearing in moist-chamber cultures, have indicated that forb microhabitats yield considerably more collections than grass microhabitats. We experimentally evaluated this pattern at the Tall Grass Prairie Preserve in Oklahoma by using litterbags prepared with autoclaved samples of grasses and forbs. We obtained a total of 162 collections representing 20 species; Perichaena pedata and Diderma effusum were the dominant species present. Total number of collections, species richness, and species diversity were significantly higher for forb microhabitats when compared to grass microhabitats. These results corroborate previous reports and demonstrate the utility of using litterbags as an experimental approach to assess myxomycete diversity and to confirm or refute observations from previous ecological studies.
Understanding differences in behavioral characteristics between invasive non-native species and native species is an important step in preventing, managing, and mitigating environmental impacts. This study examined the differences between adult life-stage native Pomacea paludosa (Florida Applesnail) and adult non-native Pomacea maculata (Giant Applesnail) grazing behavior and rates on Vallisneria americana (Tapegrass), a plant of restoration importance, to assess the potential ecological impact. We used an experimental design with entire intact specimens of Tapegrass placed in 8 tanks of each of 3 treatment groups: (1) grazed by Giant Applesnail, (2) grazed by Florida Applesnail, and (3) control with no snails. Rates of herbivory on, and physical and total biomass damage to, Tapegrass by Giant Applesnail were 1.8 cm/hr, 2.5cm/hr, and 4.2 cm/hr, respectively. Rates of herbivory on, and physical and total biomass damage to, Tapegrass by Florida Applesnail were 0.2 cm/hr, 1.2 cm/hr, and 1.4 cm/hr, respectively. The mean growth rate of Tapegrass in tanks containing no snails was 0.13 cm/hr. We used one-way ANOVAs and Tukey posthoc tests to examine statistically significant differences between the 2 gastropod species for rates of herbivory on (P = 0.006) and total biomass damage to (P = 0.024) Tapegrass. No statistical difference between the 2 species was found for the physical damage rate (P = 0.18). Statistical differences were found between controls without snails and Giant Applesnail and Florida Applesnail, respectively, for herbivory (P = 0.001, P = 0.05), physical damage (P = 0.007, P = 0.001) and total damage rates (P = 0.001, P = 0.002). The observed grazing behavior of adult life-stage specimens of the 2 species differed substantially, with Florida Applesnail grazing along blade edges and Giant Applesnail completely cutting off blades from their bases. These results also show that Giant Applesnail consumed and removed more Tapegrass biomass at a faster rate than the native Florida Applesnail. The introduction of Giant Applesnail, with its greater herbivory and total biomass damage rates over the native apple snail and behavior that removes leaf blades, may shift competitive interactions in Tapegrass communities under pressure from non-native plant invaders such as Hydrilla verticillata (Waterthyme).
Tsuga canadensis (Eastern Hemlock) is a keystone tree species currently experiencing high mortality in southeastern US forests due to Hemlock Woolly Adelgid (Adelges tsugae; HWA) invasion. Investigating the impacts of concurrent climate change on Eastern Hemlock is important given its potential direct effects on this species and possible interactions of climatic factors with the continued spread of HWA. We conducted a 2-factorial experiment in controlled-environment growth chambers to test for the main effects and interactions of projected atmospheric CO2 concentrations and transitional-season warming on gas-exchange traits of Eastern Hemlock saplings collected from a northern Georgia field site. We hypothesized that elevated CO2 would increase photosynthesis and that warming would not influence photosynthesis, given the demonstrated capacity for photosynthetic temperature-acclimation in this species. Saplings in elevated CO2 exhibited ∼30% greater leaf-level photosynthesis (A) and ∼35% greater maximum light-saturated photosynthesis (Amax) than saplings in ambient CO2. In contrast, warming did not influence A or Amax as a main effect. However, significant treatment interactions suggest that the response of Eastern Hemlock to rising CO2 could be impacted by associated warming. Specifically, when saplings were grown in elevated CO2, warming was associated with reductions in Amax, rate of respiration in the dark, and stomatal conductance, but these variables were not influenced by warming when combined with ambient CO2. An increase in the light-saturation estimate with elevated CO2 across temperature-treatment levels indicates that CO2 can be a limiting factor for Eastern Hemlock, but significant treatment interactions suggest that the capacity for this species to utilize increased CO2 may be impacted negatively by warming.
The purpose of this study was to define growth parameters, age-at-length, and the sex ratio for Rachycentron canadum (Cobia) in Port Royal Sound and the nearshore waters of South Carolina. We sampled Cobia from recreational-fishing efforts, and used otoliths to estimate age. Female Cobia (n = 245) fork length (FL) ranged from 798 mm to 1425 mm (mean = 1059 mm) and male (n = 221) FL ranged from 670 mm to 1183 mm (mean = 936 mm). The ratio of females to males was 1.1:1.0. Cobia ranged in age from 2 to 11 years; most (60.8%) were age 3. Estimates of von Bertalanffy growth parameters for Cobia were L∞ = 1212, K = 0.53, and t0 = -0.13 for females and L∞ = 1101, K = 0.51, and t0 = -0.13 for males. Life-history characteristics of Cobia as defined by this study provide managers with critical age-at-length and growth information necessary for the effective management of the species.
We surveyed for helminth parasites salvaged specimens of 27 Agkistrodon contortrix (Copperhead), 4 Agkistrodon piscivorus (Cottonmouth), and 7 Crotalus horridus (Timber Rattlesnake) collected between 2003 and 2010 from various locations in North Carolina. We detected 10 previously described helminths (2 trematodes: Ochetosoma kansensis, Travtrema stenocotyle; 1 cestode: Proteocephalus sp.; 6 nematodes: Kalicephalus inermis coronellae, Kalicephalus costatus parvus, Physalopterid larvae, Physaloptera squamatae, Capillaria colubra, Strongyloides serpentis; and 1 acanthocephalan: Macracanthorhynchid cystacanths). Herein, we report 7 new host records and 7 new geographic-distribution records with notes on host—parasite biology.
The objective of this study is to assess Tursiops truncatus truncatus (Common Bottlenose Dolphin) group behavior as a function of spatial, temporal, and vessel proximity variables within the Galveston—Port Bolivar ferry lane, in lower Galveston Bay, TX. This area is subjected to vessel traffic entering the Houston, Texas City, and Galveston ship channels and at risk for environmental accidents. We used the Galveston—Port Bolivar ferries as a platform of opportunity to observe group behavior within the ferry lane. We conducted 1412 hours of observation between 1 June and 30 November 2013 and then utilized canonical correspondence analysis to evaluate behavioral state as a function of spatial, temporal, and vessel-proximity variables. Principal response curve (PRC) analysis showed significant variation in behavioral states over time in the Bolivar and Galveston zones as compared to the passage zone. Chi-square goodness-of-fit tests showed significant deviations from expected behavior observation across zone and time block. These findings demonstrate finescale behavioral variability in an area of high anthropogenic activity.