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We document the continued population expansion of red lionfish, Pterois volitans, the first documented successful introduction of an invasive marine fish species from the western Pacific to Atlantic coastal waters of the United States. Red lionfish are indigenous to the Indo-Pacific and have apparently established one or more breeding populations on reefs off the southeastern United States. Fifty-nine specimens, most presumably adult red lionfish, were documented or collected on live-bottom reefs off North Carolina, South Carolina, and Florida, and on a manmade structure off Georgia. Observation/collection depths and bottom water temperatures for these fish ranged from 40–99 m and 13.8–24.4°C, respectively. Eleven juvenile lionfish, believed to be expatriated from southeastern waters, were collected in estuaries along the coast of Long Island, NY, at depths of 0–5 m and water temperatures ranging from 13.8–16.5 °C. Twelve of the total 70 specimens collected or observed were positively identified as red lionfish. Based on histological assessment of gonad tissue, two reproductively-active males and one immature female were collected. The life history of red lionfish, especially their reproductive biology and food habits, should be investigated along the east coast of the US to determine the potential impacts of this species on ecosystems they have invaded.
Cathy Koczaja, Laura McCall, Elizabeth Fitch, Brad Glorioso, Chad Hanna, Juliana Kyzar, Matthew Niemiller, Jeremy Spiess, Amy Tolley, Richie Wyckoff, Dennis Mullen
The purpose of this study was to investigate patterns of size-specific habitat use by banded sculpin (Cottus carolinae) in Brawley's Fork (Cumberland River Basin, TN). In a survey of three riffle and three pool habitats in a first order stream, adults were found almost exclusively in the pools, while young-of-the-year (YOY) were found almost exclusively in the riffles; juveniles were found in both habitat types. In-stream habitat-choice chambers were used to examine the velocity and depth preferences of juveniles and YOY sculpin and to determine the influence of adult presence on habitat selection of juveniles and YOY. Size-specific habitat segregation is not related to velocity differences between pool and riffle habitats. None of the size classes demonstrated a velocity preference, and the presence of adults did not affect the velocity use of the juveniles or YOY. However, adults showed a strong preference for deep habitat, YOY tended to prefer shallow habitat, both when alone and when in the presence of an adult, and juveniles strongly preferred deep habitat when no adult was present, but chose shallow habitat in the presence of an adult. The ontogenetic habitat shift from riffles to pools by juvenile sculpin may be explained by a change in predation risk as sculpin grow. The most significant predation risk to smaller sculpin is posed by larger piscivorous fish, which primarily inhabit deeper pool habitats. The greatest risk of predation for larger sculpin is posed by piscivorous mammals, reptiles, and birds, and this risk is minimized by the fishes' use of deeper pool habitats. The timing of this habitat shift appears to be a function of the density of adult sculpin, which are potential competitors/predators of the juvenile sculpin.
We sampled fishes and measured physical habitat in 14 first-order streams in north-central Mississippi to document fish community characteristics and examine the relationships between the fish communities and physical habitat characteristics. We documented 36 species and 11 families from 6943 captures. The five most abundant species were creek chub (Semotilus atromaculatus Mitchell), least brook lamprey (Lampetra aepyptera Abbot), blackspotted topminnow (Fundulus olivaceus Storer), creek chubsucker (Erimyzon oblongus Mitchell), and green sunfish (Lepomis cyanellus Rafinesque). We also observed that most streams (> 50%) were numerically dominated by: 1) Cyprinidae, 2) fishes having a maximum body size between 300–399 mm TL, 3) insectivores, and 4) guarder-nest spawners. Fish species composition of our study streams was similar to the species composition documented in other medium- and low-gradient headwater streams in the Gulf Coastal Plain. Additionally, fish community structure in first-order streams was significantly correlated with channel cross-section area, woody debris, canopy cover, water depth, velocity, wet width, and substrate types. The observed relationships between fish communities and physical habitat characteristics in first-order stream were similar to fish-habitat relationships observed by previous investigators working in northern Mississippi streams ranging in size from first to fifth-order.
A self-releasing satellite “pop-up” tag was attached to an adult male shortfin mako captured off of the southeastern United States. The tag was deployed in the spring of 2002 and detached after 60 days in an area approximately 72 km from the tagging location. Archived tag data indicated a depth range of 0 to 556 m in ambient temperatures between 10.4 and 28.6 °C. The shortfin mako demonstrated a diel pattern of vertical movement defined by greater mean depths and larger depth ranges during daylight hours. Depth and temperature data suggested a seasonal behavioral change in vertical movements associated with an increase in sea-surface temperatures during the study period.
Accurate knowledge of an organism's distribution is necessary for conserving species with small or isolated populations. A perceived rarity may only reflect inadequate sampling effort and suggest the need for more research. We used a recently developed method to evaluate the distribution of a rare fish species, the blackmouth shiner Notropis melanostomus Bortone 1989 (Cyprinidae), which occurs in disjunct populations in Mississippi and Florida. Until 1995, N. melanostomus had been collected from only three localities in Mississippi, but in 1995, eight new localities were discovered. We analyzed museum records of fish collections from Mississippi, Florida, and Alabama to compare sampling effort before and after 1995. Results supported our predictions that 1) pre-1995 data would indicate inadequate sampling effort in Mississippi, 2) additional post-1995 sampling improved confidence in the currently known Mississippi distribution, and 3) there has not been enough sampling to accurately represent the actual distribution of N. melanostomus in Florida and across its entire known range. This last prediction was confirmed with the recent (2003) discovery of the first N. melanostomus in Alabama.
We conducted a thorough survey of the Bogue Chitto River fish assemblage from February 1996 to January 1997 to examine long-term trends in the assemblage by comparing our findings to surveys conducted in 1971–1974 and 1987–1988. The 1971–1974 survey described an assemblage dominated by Cyprinidae (50%), Percidae (9%), and Ictaluridae (8%). Numerically abundant species included Notropis longirostris (19%), Cyprinella venusta (13%), and Percina sciera (10%). The 1987–1988 survey described an assemblage dominated by Cyprinidae (74%), Percidae (9%), and Centrarchidae (9%). The numerically dominant species were C. venusta (36%) and N. longirostris (16%). Our survey described an assemblage dominated by Cyprinidae (75%), Percidae (8%), Centrarchidae (6%), and Poeciliidae (6%). We identified a decline in the relative abundance or possible extirpation of over twenty species during the 27-year period and the numerically dominant species was C. venusta (57%). Using Morisita's Index of Similarity, we found relatively low faunal similarity between the 1970–1974 survey and our study, but relatively high similarity between the 1987–1988 survey and our survey. In addition, assemblage evenness and heterogeneity decreased over time, indicating a change in the system's fish fauna from one with relatively high species evenness and diversity to a fauna dominated by a few, abundant species. We speculate that increased siltation has contributed to changes in the Bogue Chitto River fish assemblage because many of the declining species were benthic minnows and darters, which would be adversely effected by increasing substrate loads.
In coastal Louisiana many restoration projects are approved based on assumed regeneration of submerged aquatic species (SAV) in shallow marsh interior ponds. In this study, we estimated seed bank size and composition of shallow water areas in oligohaline fringing and restored (terraced) marsh, and a freshwater managed (impounded) marsh, located in Sabine NWR, LA, using the sieving method. For the same marshes, we also provided an estimate of the readily germinable fraction of the seed bank using the germination method. Sieving results indicated that restored marsh edges had very low seed densities (5034 seeds/m2) compared to fringing marsh (331,185 seeds/m2), although species composition was similar. Managed freshwater marsh ponds had more diverse seed banks and mid-range seed densities (80,500 seeds/m2). Viability estimates of dominant species in the seed bank reduced seed density estimates at all sites by as much as 10 fold (fringing marsh: 36,185 seeds/m2; restored marsh: 859 seeds/m2; managed marsh 44,388 seeds/m2) suggesting that a correction factor should be applied to future seed density estimates in this region. Seedling emergence was significantly higher in the managed marsh under drawdown conditions (> 2500 seedlings/m2) as compared to flooded conditions (< 500 seedlings/m2; ANOVA, p = 0.0001). Seedling emergence in oligohaline marsh was significantly affected by salinity and management (fringing, restored) (ANOVA, p = 0.0186). Fringing marsh at 0 g/L had the highest seedling emergence (> 500 seedlings/m2). At higher salinities, fringing and restored marsh had similar emergence (< 150 seedlings/m2). Results indicate that recruitment is likely to be more successful under drawdown conditions, and in low salinity conditions. However, both a lack of SAV emergence in the germination experiment and a lack of SAV seeds in the seed banks using the sieving method suggest that reliance on seed banks for the restoration of shallow water areas in southwest Louisiana may prove unsuccessful.
The genetics of small population size is of considerable interest to conservation biologists and land managers concerned with maintaining genetic diversity in populations of rare plants. In this paper, I present evidence obtained through starch gel electrophoresis of allozymes that an isolated population of Cleistes bifaria (Fern.) Gregg and Catling is multiclonal with levels of genetic diversity comparable to other taxa in the Orchidaceae. A total of 24 unique multilocus genotypes were resolved by eight alleles expressed by three polymorphic loci in a census of 64 aboveground stems. Levels of clonal diversity and evenness in the distribution of genotypes indicate that the population rapidly responds to favorable habitat conditions maintaining allozyme diversity despite repeated population contractions to few reproductive individuals. Sixty stems (35 flowering) had appeared in a newly created field after only five years with allozyme and clonal diversity mirroring that found in a long-existing habitat. The population genetic data obtained from allozymes plus population monitoring and knowledge of site history suggest that intrapopulation genetic variation is maintained within persistent individual clones that apparently survive underground during periods of adverse environmental conditions.
Hybrid imported fire ants (S. invicta × S. richteri) outcompeted several native ant genera at baits in pasture and field sites in southeastern Tennessee. They more quickly discovered and recruited to baits than native ants, and they ultimately controlled more baits. After half of the fire ant mounds were experimentally removed by poisoning, native ants were quicker than fire ants to discover and recruit to baits, but fire ants still ultimately controlled about half the baits. Interactions between fire ants and native ants at baits were very rarely directly aggressive; rather, either the later arrival left or the different species spatially partitioned the bait without fighting. Occasionally control of a bait changed between species, but such shifts were not accompanied by aggression between the contenders. These results suggest that, like the red imported fire ant, Solenopsis invicta, the hybrid fire ant outcompetes native ants in disturbed habitats. This competitive superiority rests at least partly on numbers, and interference competition is not operating at the scale of individual baits.
Sixteen species of odonates, representing 9.2% of Alabama's odonate fauna, were collected from flowing waters 10–450 m wide in the poorly surveyed Mobile/Tensaw Delta of Baldwin County over a one-year period. The number of species was positively correlated with the number of specimens per site, with sites nearest Mobile Bay having fewer species, possibly reflecting higher salinities. Odonate assemblages in large flows of the Delta are unpredictable in terms of species co-occurrence, and fit a model of non-equilibrium community structure.
Silphid larvae of three species of potential forensic importance were studied to verify total instar number, document instar size classes, and illustrate frequencies of instars through time. Larval material was collected at seven large vertebrate carcasses during spring 1999 in East Baton Rouge Parish, LA. A total of 534 Necrodes surinamensis (F.), 80 Oiceoptoma inaequale (F.), and 13 Necrophila americana (L.) larvae were evaluated using three morphological measurements. Three instars were identified for N. surinamensis and O. inaequale. The distance between dorsal stemmata was found to be a more reliable indicator of instar size than body length with results (in mm) as follows for N. surinamensis and O. inaequale, respectively: 1st (0.87–1.09), (0.95–1.08), 2nd (1.30–1.60), (1.28–1.51), and 3rd (1.78–2.07), (1.66–1.79).
This study examines the relationship between Red-cockaded Woodpecker (Picoides borealis Vieillot) reproduction and rainfall during May when group members are provisioning nestlings with food. Patterns of variation over a 4-year period of approximately 30 woodpecker groups suggested that the mean number of hatchling deaths was positively related to the amount of rainfall that occurred during May. During the same 4 years, the mean number of young fledged from nests appeared to be inversely related to May rainfall. Observations of nestling provisioning behavior during four breeding seasons indicate that group members slow down or stop feeding nestlings during periods of heavy rainfall. During a 20-year period, total May rainfall was related to the percentage of woodpecker groups producing fledgling-sized young in cavities (rs = −0.56, P = 0.0097) and the occurrence of El Niño events (rs = −0.50, P = 0.0347).
Black Vultures (Coragyps atratus) and Turkey Vultures (Cathartes aura) are found throughout many parts of southeastern North America, but relatively little is known about the factors that may negatively impact their populations. We surveyed both species for blood parasites to learn more about factors that may influence their health. During 2000–2001, 22 Black Vultures and 11 Turkey Vultures were live-captured at the Savannah River Site in South Carolina. Two blood smears from each bird were made on microscope slides, stained, and examined at 1000× magnification. A Haemoproteus sp. was found in blood smears of one Turkey Vulture and microfilariae were detected in smears of one Black and two Turkey Vultures. We did not detect Leucocytozoon or Plasmodium in our samples, even though they have been reported in vultures from other parts of eastern North America.
Iguana iguana is a well-established introduced species in southern Florida, including a large population on Key Biscayne. In its native range, I. iguana is known to be almost strictly herbivorous. Juveniles are often reported to be somewhat omnivorous, but prey items are rarely identified. The tree snail Drymaeus multilineatus is common in southern Florida, where it is found on stems and leaves and in edificarian habitats. The examination of I. iguana stomachs from Bill Baggs Cape Florida State Park, Key Biscayne, resulted in the discovery of D. multilineatus in two lizards, including 12 snails in one juvenile I. iguana. The large and rapidly growing I. iguana populations in southern Florida may have the potential to devastate some highly localized native species of tree snails.
We assessed daily and seasonal activity and movements of reintroduced elk in eastern Kentucky from March 1999 to November 2000. Elk activity was determined by monitoring radio-transmitter pulse rate changes, and movements were calculated using hourly ground locations. A total of 1469 activity bouts and 1441 locations were collected on 38 and 32 radio-collared elk, respectively. Elk exhibited a tri-modal activity pattern with peaks near dawn, dusk, and midnight. Activity did not differ between seasons, although it was influenced by gender and time of day. Peak movements corresponded with peaks in activity at dawn and dusk, and increased from spring to winter. Elk were more gregarious and visible during the fall and winter, which increased their susceptibility to human disturbance and caused longer movements.
We report use of an underground roost by an adult male evening bat (Nycticeius humeralis) during winter in southwestern Missouri. The bat was fitted with a radio-transmitter and followed to tree roosts for 28 days before it was found in a hole covered by leaf litter at the base of a live white oak tree (Quercus alba). The bat remained in the underground roost for 3 days that coincided with extremely cold ambient temperatures before moving back to a tree roost.
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