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Eichhornia crassipes (Waterhyacinth) occurs in isolated populations along the Waccamaw River in northeast South Carolina. Although actively managed with herbicides, plant biomass and growth in this coastal, blackwater river have not been measured. We located three persistent populations in protected backwaters during spring 2009 and used sequential harvests to measure biomass accumulation and allocation. Relative growth over one month in existing populations and in two downriver sites was measured by placing plants in floating cages. A separate experiment was conducted to determine salinity tolerance. Mean total biomass in the persistent populations was relatively low but increased from 202.9 g/m2 in spring to 380.1 g/m2 in fall, with leaves as the largest biomass component (72%). Absolute growth and leaf nutrient content for nitrogen, phosphorus, and potassium were highest for caged plants placed in a downriver site influenced by the Pee Dee River, a redwater system. Our results suggest that Waterhyacinth extent and growth in the Waccamaw River are limited by nutrient availability, but other factors may also be involved.
The seasonal movements of Lepisosteus osseus (Longnose Gar) are largely unknown. The goal of this project was to characterize spawning movements and seasonal distributions by using acoustic tagging methods and examining historical catch records from a trawl survey. This is the first time that movements have been studied for an estuarine population of Longnose Gar. Two individuals moved greater minimum distances (69 and 74 km) than found in the only other report on movement in this species. Spawningground residency time, collected from two tagged Longnose Gar, was approximately one month, and tidal periodicity was observed for one of the two fish. Data from a fisheries independent trawl survey were used to examine seasonal catch distributions in Longnose Gar and represents the first report of winter distributions for this species. Winter locations occurred both alongshore and mid-channel, and the distributions were similar to those in the summer and fall.
Concerns over the recent introduction of Micropterus punctulatus (Spotted Bass) on native M. salmoides (Largemouth Bass) and M. cataractae (Shoal Bass) prompted a one-year investigation into the food habits of these three congeneric species to determine diet overlap and potential for trophic competition in the Flint River, GA. Diet analyses among species were conducted for two size classes offish: juvenile (<200 mm total length) and subadult (200–300 mm TL). Because Spotted Bass had become established in the Flint River only a few years prior to this study, few fish >300 mm were collected; thus, diet overlap was not compared among species for larger fish. Juvenile and subadult Largemouth Bass diets were dominated by fish in all seasons, mainly sunfishes (e.g., Lepomis auritus, L. macrochirus). In contrast, Shoal Bass diets were generally dominated by insects and crayfish in the juvenile and subadult size classes, respectively. Juvenile Spotted Bass diets were variable and dominated by fish and insects depending on season. Overall, diets of introduced Spotted Bass appeared to occupy an intermediate position between Shoal Bass and Largemouth Bass. Significant diet overlap between Shoal Bass and Spotted Bass occurred in 50% of the samples, but only in 29% of the samples between Spotted Bass and Largemouth Bass and never between the two native Bass species. Thus, concerns about the trophic effects of Spotted Bass on Shoal Bass appear to be legitimate.
The southeastern United States contains ca. 250 species of crayfish. Of these, 85 are historically known from Alabama. Previous studies have shown that the Sipsey River drainage in western Alabama is a diversity “hotspot” for freshwater mussels (42 spp.) and fishes (102 spp.). This is attributed to diverse geologic features, an intact floodplain, lack of impoundments, and lack of urban centers. Intensive sampling of the Sipsey River drainage over a 2-year period resulted in a collection of 294 crayfish representing 12 species. Three of these species, Cambarus ludovicianus, Orconectes chickasawae, and Procambarus vioscai paynei are of conservation concern. Our results indicate that the Sipsey River harbors a greater richness of crayfish species per area than other drainages surveyed to date in Alabama.
Gambusia affinis (Western Mosquitofish) were sampled from 18 sites representing marsh, forested wetlands, and agricultural wetlands in south Louisiana to determine distribution and infection parameters of Eustrongylides ignotus, a potentially lethal nematode parasite of wading birds, (n = 400 per site). Overall, prevalence of infection was 0.3%, with significantly higher prevalence in agricultural wetlands than in marshes or swamps. Our findings are similar to work in Florida suggesting parasite prevalence is higher in disturbed wetlands, and suggest that birds foraging in crayfish ponds and rice fields may be at increased risk of exposure.
Many secretive marsh bird (SMB) species nest within rice fields, yet in most regions we do not understand the extent to which these birds use such habitats. In the summers of 2007 and 2008, we investigated summer use of rice fields by SMBs in northeast Louisiana and evaluated the local (within 100 m) and landscape (within 1 km) habitat characteristics influencing site selection. We did not encounter any SMB species in 2007, but we encountered low densities of Ixobrychus exilis (Least Bitterns), Rallus elegans (King Rails), and Fulica americana (American Coots) in mid-July of 2008. It is unclear whether or not the birds we detected were actually breeding in the rice fields, or merely using them as late summer foraging areas. When we combined detections of all species, we found that probability of occupancy was positively influenced by the proportion of the local habitat dominated by flooded ditches containing herbaceous emergent vegetation. Ditches likely provide refuge and resource alternatives that may be particularly important to these birds in the late summer when rice fields are drained and harvested. However, given that SMBs were detected at less than 10% of the 72 rice fields we surveyed, it appears as though Mississippi Alluvial Valley rice fields contribute very little toward supporting SMB populations.
From 1975 to 2009, 186 surveys for Rynchops niger (Black Skimmer) nests were conducted in South Carolina. The state was not thoroughly monitored until 1988, and between 1988 and 2009 nesting numbers were stable. The mean nest count from 1988 to 2009 was 889 ± 55 SE, (n = 21 years). Twenty-six different sites supported nesting colonies with Cape Island, Cape Romain National Wildlife Refuge being used most often (24 years). Publicly owned lands were used more often than privately owned lands, and seabird islands—small ephemeral islands with other species of seabirds nesting on them—supported colonies more often than other habitat types. The number of skimmer nests was much lower than nesting records prior to this study; thus, intensive monitoring during the breeding season should continue to provide managers with information that can assist in increasing fecundity and protect optimal nesting habitat.
Point-count surveys are useful in collecting information on breeding birds; however, species that are elusive, occupy dense forests, or call infrequently may be undersampled. In this study, we examined the responsiveness of Coccyzus minor (Mangrove Cuckoo) to call playbacks in southern Florida from May to June in both 2010 and 2011. Our objective was to determine if playback surveys would increase the detectability of Mangrove Cuckoos. At each of the 111 experimental points, either recorded Mangrove Cuckoo vocalizations (treatment) or no vocalizations (control) were broadcasted. We detected Mangrove Cuckoos at 14 of the 67 treatment points (20.9%) and at 1 of the 44 control points (2.3%), suggesting that using call-playbacks significantly increased the likelihood of detecting a Mangrove Cuckoo (P = 0.01) as compared to passive pointcount methods. In recent years, sharp declines in Mangrove Cuckoo populations have been noted, and little is known about their overall ecology. Before conservation for this species can take place, it is necessary to fill basic information gaps such as distribution and abundance. Once distribution is better understood, critical habitat can be protected and monitoring the effects of climate and habitat change can occur. Increasing the detectability of these birds is an important step toward achieving these goals.
Genetic diversity within and among nine Andropogon gerardii (Big Bluestem) populations from various physiographic regions of North and South Carolina was assessed. Genetic diversity was high at both the species level and at the population level. At the species level, percent polymorphic loci (P) was 96.4% (27 of 28 loci), the number of alleles per polymorphic locus (AP) was 4.07, and genetic diversity (He) was 0.425. Mean within population values were P= 82.6%, AP = 2.68, and He = 0.351. Within population genetic diversity (He) ranged from 0.190 to 0.466. Allelic richness values per population ranged from 37 to 71. The proportion of genetic diversity among populations (Gst) was 0.166. Mean genetic diversity for the 3 larger populations (He = 0.369) and within the 6 smaller populations (He = 0.341) did not differ significantly (P = 0.554). Nei's unbiased genetic identity between pairs of populations ranged from 0.652 to 0.975. Mean genetic identity of individual populations with the 8 other populations ranged from 0.71 to 0.89. A Mantel test showed no significant genetic isolation by geographic distance (r = 0.065; P = 0.614). While banding patterns for most of the loci were consistent with disomic inheritance, two loci (PGI3; UGPP1) displayed patterns consistent with tetrasomic inheritance. Results of this study suggest that Big Bluestem populations in the Carolinas were once more widespread.
Tardigrades were recovered from samples of moss and lichen growing on the bark of seven species of trees on the University of Central Arkansas (UCA) campus in Conway, AR. Of the 11 genera of tardigrades previously reported from the state, five were found in the UCA campus samples; of the 25 species previously reported, five were found in the UCA campus samples. Two species (Milnesium eurystomum, Macrobiotus polyopus) are new records for the state; one species of Echiniscus (arctomys group) could not be identified and may be new. Tardigrades were not uniformly distributed among available habitats (moss, lichen) or substrates (trees).
Macroalgal assemblages were described from Gray's Reef National Marine Sanctuary (GRNMS), GA and compared to records from 25 years ago. For quantitative comparisons in species richness and biomass, divers collected algae from Searle's four northern sites and another four southern sites (n = six 400-cm2 quadrats per site). To compare species richness among sites, algae were also collected across limestone reefs at each site, and any new species were added to those recorded from the quadrat samples. Of the 55 species identified, 8 were new GRNMS records, 4 were new records to Georgia, and 36 had been recorded previously. Nine species were present at all of the 8 sites. Although species richness per site was significantly greater in southern GRNMS, biomass and species richness per 400 cm2 were similar between northern and southern sites. Sediment movement likely contributed to variability in species composition across the reefs.
We provide a review of Dasypus novemcinctus (Nine-banded Armadillo) food studies and report on the diet on Cumberland Island, GA. Major invertebrate foods eaten by Armadillos on Cumberland Island were ants (19.3%); beetles, adults and larvae (27.4 %); centipedes (6.5%); lepidopterans, mostly larvae (caterpillars, 13.2%); millipedes (5.7%); spiders (2.1%); and sowbugs (2.2%). Vertebrates eaten (1.9% volume) were mostly frogs and lizards. Plant material comprised about 12% of the volume, including much fruit such as Melia azedarach (China Berry), Vitis (grapes), Ampelopsis arborea (Pepper Vine), and Serenoa repens (Saw Palmetto). The subterranean fungi, Endogonaceae, were eaten by 23.9% of the Armadillos, comprising 1.6% of the volume of their diet. The millipede Narceus sp. appears to have been greatly reduced, based on the significant reduction of this species as a component of the gut content over three decades. This reduction could be due to Armadillo predation. Ants, scarabaeid adults and larvae, and spiders also showed significant decreases during the period of study, which could be a result of Armadillo predation. A number of items—elaterid larvae, crickets, caterpillars, centipedes, sowbugs, and Endogonaceae—showed significant increases as components of Armadillo stomachs, but it is not known whether these changes might be related to Armadillo predation. The increases could have been due to other causes such as habitat or climatic changes.
Studies of Urocyon cinereoargenteus (Gray Fox) in suburban landscapes are rare. Past work has suggested that this species will only tolerate urbanization to a certain density of residences (50–125 residences/km2). To test this, we employed visual observations and camera traps to monitor Gray Fox activity within a suburban and adjacent rural property from January to July 2011. We also used a geographical information system (GIS) to calculate the density of buildings associated with both properties. We observed Gray Foxes and detected them with camera traps in our properties on numerous occasions. GIS analyses revealed an estimated suburban density of 237–347 residences/km2 (depending on spatial scale) and rural density of 50 residences/km2. The number of Gray Fox observations did not differ greatly between rural and suburban properties, although the peak periods of Gray Fox observations varied by site. We propose that a tolerance for high suburban building density exhibited by Gray Foxes at our site is related to the large amount of mature wooded buffers located adjacently.
We studied the denning chronology, den type, and den-site characteristics of Ursus americanus floridanus (Florida Black Bear) in Ocala National Forest (ONF) and the adjacent residential area of Lynne, FL. We monitored 35 radio-collared females for 62 den years from 1999 through 2003. Den entry dates did not differ between parturient females (females that gave birth to cubs during the winter) and nonparturient (solitary females or females with yearlings) (P = 0.139). Females with cubs exited dens later (P < 0.001), and denned longer (mean =113 ± 3.3 days) than females without cubs (mean = 54 ± 6.0 days; P < 0.001). Among females with cubs, primiparous females entered dens on average 28 days later than multiparous females (P = 0.003); however, exit date and duration of denning did not differ between the two groups. Female bears denned in ground nests most frequently (n = 45), followed by excavated dens (n = 7); one female used a tree den. Compositional analysis revealed that denning habitat selection occurred in ONF, with sand pine as the preferred denning habitat, followed by swamp and pine flatwoods habitats. Denning habitat selection was not evident in Lynne, although the majority of females denned in swamp habitats. Parturient females often denned in ecotones with dense vegetation, due perhaps to the fact that such ecotones offer better protection to the female and her cubs from potential predators and weather elements. Habitat management activities should be limited during peak denning of parturient females, from late December to mid-April, particularly in Sand Pine - xeric oak and pine flatwood - swamp ecotones.
Odocoileus virginianus (White-tailed Deer) have become overabundant in many urban and suburban areas, which can cause concern about exposure of humans and pets to zoonotic pathogens. Bald Head Island, NC is a small barrier island that has experienced ongoing residential development since the mid-1980s and has a relatively high deer density (15–17 deer/km2). To address concerns expressed by residents, we screened ≈13% of the White-tailed Deer population for potential zoonotic pathogens. We collected blood from 8 deer in January through March 2008 and 5 deer in January 2009. We tested sera for antibodies to Anaplasma phagocytophilum, Borrelia burgdorferi, and six serovars of Leptospira interrogans; and whole blood samples for Bartonella spp. and B. burgdorferi DNA. All sera were negative for antibodies to L. interrogans; two samples were seropositive for A. phagocytophilum, and one was seropositive for B. burgdorferi. Whole blood PCR results were negative for Bartonella spp. and B. burgdorferi. Continued surveillance for wildlife diseases on Bald Head Island is necessary to determine prevalence of specific pathogens, their impacts on the White-tailed Deer population, and the risk of exposure to humans and pets.
We radio-tracked 3 male and 1 female Lasiurus intermedius (Northern Yellow Bat) to 16 unique roosts on Sapelo Island, GA in summer 2010. All bats roosted in Tillandsia usneoides (Spanish Moss) hanging in hardwood trees. Trees used as roosts were similar in height as surrounding trees but were larger in diameter. Mature hardwood stands appear to be important roosting habitats for Northern Yellow Bats in areas where Pinus (pine) and mixed-pine hardwood habitats dominate the landscape.
As a result of declining populations and reduced availability of suitable habitat, Ambystoma bishopi (Reticulated Flatwoods Salamander) and A. cingulatum (Frosted Flatwoods Salamander) are federally listed as endangered and threatened, respectively, by the United States Fish and Wildlife Service under the Endangered Species Act. Recovery efforts are hindered by a lack of basic natural history information. Although the fossorial life history of ambystomatid salamanders often precludes direct observation of adults and juveniles, an incidental encounter of A. bishopi climbing on Aristida stricta (Wiregrass) sparked a new search effort. On 13 occasions from 29 April 2010 to 23 November 2011, we examined herbaceous ground cover in and around six known breeding wetlands in the Florida panhandle, documenting 36 observations of flatwoods salamanders (10 adults and 26 juveniles), 30 of which were climbing up to 0.5 m above the ground in Wiregrass. These observations led us to hypothesize that Wiregrass, a fire-dependent grass species associated with flatwoods salamander breeding habitat, may be used by juvenile and adult flatwoods salamanders as a foraging substrate (foliage) and/or as refugia (foliage and root base). Although these observations are interesting, further research is needed to determine if the salamanders are selectively using wiregrass and if a foraging and/or refugial advantage is gained by climbing.
Aphredoderus sayanus (Pirate Perch) is a widespread species whose life history is the subject of only a few studies. I recorded life-history data from a small sample of Pirate Perch collected from an intermittent stream in midcontinental highlands of Arkansas (Batesville, Independence County) on 30 June 2004. Our small sample suggests variation in prey consumption rates between sexes during the breeding season and in allocation to reproduction among females. Our survey confirmed that Pirate Perch from Arkansas have similar insectivorous diets to those reported from other regions.