Observations on the plankton of some Costa Rican lakes

We sampled 30 lakes in Costa Rica in the wet season (July–August) of 1991 for phytoplankton (with integrated and whole water samples), and 17 for zooplankton (with net tows). Taxa of plankton and community richness were poorly related to geography, morphology, chemistry, and other biota. Neither the zooplankton nor the phytoplankton appeared to influence the composition of the other, and neither were apparently influenced by the presence of fish.Phytoplankton richness reflected primarily sampling method, but also tended to decrease with elevation and with Secchi disk depth, and tended to increase with pH and alkalinity. Chlorophytes were the most abundant division in 14 lakes; these lakes tended to be unstratified, turbid, and located at higher elevation. Diatoms were common in 4 of the 7 lakes with elevated silica (over 30 ppm). Each lake showed at least a 3 : 1 dominance by copepods, cladocera, or insect larvae. Copepods dominated 7 of the 17 lakes, most of which were shallow, turbid, and had low alkalinity. Cladocera dominated 7 lakes that were typically deeper and located at low-to mid-elevations. Insect larvae dominated two small, turbid lakes.     

Molecular zoogeography of freshwater fishes in the southeastern United States

Restriction fragment length polymorphisms in mitochondrial DNA (mtDNA) were used to reconstruct evolutionary relationships of conspecific populations in four species of freshwater fish—Amia calva, Lepomis punctatus, L. gulosus, and L. microlophus. A suite of 14-17 endonucleases was employed to assay mtDNAs from 305 specimens collected from 14 river drainages extending from South Carolina to Louisiana. Extensive mtDNA polymorphism was observed within each assayed species. In both phenograms and Wagner parsimony networks, mtDNA clones that were closely related genetically were usually geographically contiguous. Within each species, major mtDNA phylogenetic breaks also distinguished populations from separate geographic regions, demonstrating that dispersal and gene flow have not been sufficient to override geographic influences on population subdivision.—Importantly, there were strong patterns of congruence across species in the geographic placements of the mtDNA phylogenetic breaks. Three major boundary regions were characterized by concentrations of phylogenetic discontinuities, and these zones agree well with previously described zoogeographic boundaries identified by a different kind of data base—distributional limits of species—suggesting that a common set of historical factors may account for both phenomena. Repeated episodes of eustatic sea level change along a relatively static continental morphology are the likely causes of several patterns of drainage isolation and coalescence, and these are discussed in relation to the genetic data.—Overall, results exemplify the positive role that intraspecific genetic analyses may play in historical zoogeographic reconstruction. They also point out the potential inadequacies of any interpretations of population genetic structure that fail to consider the influences of history in shaping that structure.     

Agglutinins from marine macroalgae of the southeastern United States

Protein extracts from 22 species of marine macroalgae from Florida and North Carolina were compared for their abilities to agglutinate sheep and rabbit erythrocytes. Protein extracts from 21 algal species agglutinated rabbit erythrocytes compared to 19 for sheep erythrocytes. However, agglutination by brown algal extracts was variable. The agglutination produced by protein extracts from Dictyota dichotoma could be blocked by addition of polyvinylpyrrolidone. Protein extracts from North Carolina macroalgae were also tested against five bacterial species. Three of these agglutinated bacterial cells. Ulva curvata and Bryopsis plumosa agglutinated all five species. Protein extracts from five species of Florida algae were tested for their effects on mitogenesis in mouse splenocytes and human lymphocytes. Gracilaria tikvahiae HBOI Strain G-5, Ulva rigida and Gracilaria verrucosa HBOI Strain G-16S stimulated mitogenesis in mouse splenocytes, while Gracilaria tikvahiae HBOI Strain G-16stimulated mitogenesis in human lymphocytes.     

Phylogeography of the salamander genus Pseudobranchus in the southeastern United States

This study provides an extensive set of mitochondrial cytochrome b sequences for the salamander genus Pseudobranchus of the southeastern United States. These sequences were analysed by multiple phylogenetic methods that support a single set of major phylogeographic divisions for its two corroborated species (P. axanthus and P. striatus). These phylogeographic divisions overlap with the geographic breakpoints of other freshwater and terrestrial taxa in this region. Collectively, these overlapping patterns highlight the Central Highland and Tifton/Vidalia uplands as a significant barrier to Atlantic vs. Gulf coast groups, while reconfirming the phylogeographic significance of the Altamaha and Apalachicola river drainages. Despite their distinct phylogeographic split, P. striatus from west and east of these uplands are not currently recognizable as separate species according to the concordance principles for species definition.     

Observations on the Occurrence of the Parasitic Ciliate Synophrya in Decapods in Coastal Waters off the Southeastern United States*

SYNOPSIS. Past reports of Synophrya, the only apostome ciliate known to harm its host, indicated that it was restricted in its distribution and in the hosts it can infect. In recent collections of decapods from the off-shore waters of North Carolina and Georgia, 30% of all specimens were infected with Synophrya. Forty-four percent of all the species collected had individuals infected with Synophrya, and 63% of all the families collected contained species that had infected individuals. There is no obvious structural or phylogenetic relationship between these families that explain why they are infected. The presence of Synophrya may be related to salinity since decapods captured in estuaries were never infected and decapods captured close to shore were only rarely infected. The salinities of these waters range from 15–35%, but the salinity of the off-shore waters where the great majority of infected specimens was found ranges only from 35–36%.     

Observations and comments on the body temperatures of some New Zealand reptiles

Abstract

Rectal body temperatures (BTs) of tuataras (Sphenodon punctatus) and of endemic, ovoviviparous gekkonid lizards—mainly Hoplodactylus maculatus (=H. pacificus) and Heteropholis manukanus—were taken together with ambient temperatures during early summer 1970 in areas of central New Zealand. The results, combined with earlier data, enable a number of conclusions to be drawn. (a) The preferred body temperature of heliotherm reptiles is best deduced from the mode of rectal BTS taken in the field, but that of non-heliotherms, when unimodal, from the median or mean. (b) Among Gekkonoidea, specific thermal relations are highly variable in several ways. (c) Sphenodon foraged on cool nights at BTs of 10.5–12.5°c, yet basked in the forest by day at BTs up to 24°c; in pasture it apparently basks within the burrow entrance. (d) Similarly, H. maculatus foraged at night at BTs of 10–13°c, but by day thermoregulated at BTs up to 33°c by ‘indirect basking’ (under thin cover) or ‘protected basking’ (in crevices penetrated by solar radiation). The average BT of females was 2°c higher than that of males, presumably because many females were gravid. (e) H. manukanus is (tertiarily) diurnal, and thermoregulated by basking up to a BT of 31 °c. Towards evening it apparently cooled down voluntarily. (f) Whereas a high daytime BT probably assists digestion in nocturnal foragers, a voluntary low night-time BT in diurnal reptiles may help to conserve energy.     

Necropsy findings and arbovirus surveillance in mourning doves from the southeastern United States

Mourning doves (Zenaida macroura) are the most abundant and widespread native member of the columbid family, as well as a major migratory game species, in the United States. However, there is little information on mortality factors in mourning doves. Records of necropsy accessions at the Southeastern Cooperative Wildlife Disease Study (SCWDS) from 15 southeastern states, from 1971 through 2005, were reviewed. One hundred thirty-five mourning doves were submitted from nine states during the 35-yr period. Trichomonosis constituted 40% (n = 54) of all diagnoses and was the most frequent diagnosis. Toxicoses and avian pox constituted 18.5% (n = 25) and 14.8% (n = 20) of all diagnoses, respectively. Remaining diagnoses included trauma, suspected toxicosis, Ascaridia columbae infection, suspected tick paralysis, and undetermined. Adults were observed more frequently with trichomonosis (94.1%) and toxicoses (68%) as compared to juveniles, but a gender predisposition was not apparent for either disease. Age and gender predilections were not apparent for cases of avian pox. The majority of the trichomonosis and avian pox cases were observed in the spring-summer, whereas the majority of the toxicosis cases were observed in the winter-spring. Additionally, the Georgia Department of Human Resources-Division of Public Health and West Virginia Department of Health and Human Resources submitted 809 mourning doves to SCWDS from 2001 through 2005 for West Nile virus surveillance efforts. West Nile virus was isolated from 2.1% (n = 17) and eastern equine encephalitis virus (EEEV) was isolated from 0.2% (n = 2) of the submitted birds.     

Atrichum cylindricum (Polytrichaceae), an overlooked moss in the southeastern United States

The new combination,Atrichum cylindricum (Willd. ex Weber) G. Smith is made for a moss described in 1741 by Dillenius, based on a Clayton specimen from Virginia. This species, which has been overlooked by American bryologists, is now known from the southern Atlantic and Gulf coastal plain, and the Cumberland Plateau in eastern Tennessee.Atrichum undulatum var.attenuatum Bruch & Schimp. is a synonym. Illustrations of the species and a map of its distribution are included.     

Studies on endoparasites of the black bear (Ursus americanus) in the southeastern United States.

Examination of 53 black bears (Ursus americanus) from six states in the southeastern United States revealed at least 17 species of endoparasites, including Sarcocystis sp., Spirometra mansonoides (spargana), Macracanthorhynchus ingens, Ancylostoma caninum, Arthrocephalus lotoris, Baylisascaris transfuga, Capillaria aerophila, Capillaria putorii, Crenosoma sp., Cyathospirura sp., Dirofilaria immitis, Gnathostoma sp., Gongylonema pulchrum, microfilariae, Molineus barbatus, Physaloptera sp. and Strongyloides sp. Twelve of these represent new host records for black bear, and two are considered to be new species. Data are presented on prevalence, intensity and geographic distribution of each species. Pathologic effects were associated with infections of spargana of S. mansonoides and adults of C. aerophilia.     

Diseases diagnosed in wild turkeys (Meleagris gallopavo) of the southeastern United States

Diagnostic findings are presented on 139 sick or dead wild turkeys examined during the period 1972 through 1984. Turkeys originated from eight southeastern states (Alabama, Arkansas, Florida, Georgia, South Carolina, Tennessee, Virginia, West Virginia) and included 31 turkeys categorized as capture-related mortalities and 108 turkeys categorized as natural mortalities. Frequent diagnoses (greater than or equal to 10% of case accessions) in the natural mortality group were trauma, avian pox, and histomoniasis. Less frequent diagnoses (less than or equal to 4% of case accessions) included malnutrition/environmental stress syndrome, coligranuloma-like condition, crop impaction, bumblefoot, organophosphate toxicosis, infectious sinusitis, a lympho-proliferative disease, salmonellosis, aspergillosis, toxoplasmosis, crop trichomoniasis, and melorheostosis.     

Root-infecting fungi associated with a decline of longleaf pine in the southeastern United States

A 35-year-old longleaf pine stand exhibited trees in various stages of decline. A study was conducted to determine root-infecting fungi and other abnormalities associated with varying degrees of crown symptoms. A four-class crown symptom rating system was devised according to ascending symptom severity. Leptographium procerum and L. terebrantis were significantly associated with increasing crown symptom severity. Heterobasidion annosum was also isolated in higher frequency as crown symptoms increased. Also, evidence of insects on roots increased as did amount of resinosis observed. Edaphic and silvicultural factors may interact with these pathogens and insects to pose a pathological limitation on longer-term management objectives. Further research is needed to determine relationships among various edaphic, silvicultural, and biological factors associated with the decline syndrome on this site. This revised version was published online in June 2006 with corrections to the Cover Date.     

Biogeography of the southeastern United States: a comparison of salamander phylogeographic studies

Most phylogeographic studies of species from the southeastern United States have shown a simple east-west division of mtDNA variation. However, a study of the salamander Ambystoma maculatum resulted in a more complex pattern that includes a close affinity between populations from the Central Highlands of Missouri and Arkansas and the Coastal Plain separated by a genetically distinct central group of populations. We test the generality of this observation by surveying mitochondrial DNA (mtDNA) variation in the closely related species A. talpoideum. An Ambystoma-specific intergenic spacer was amplified and sequenced. The 26 resulting haplotypes varied from 380 to 800 base pairs, and alignments, including the outgroup, required 101 insertions/deletions. Sequence divergence among haplotypes ranged from 0.001 to 0.758. Population subdivision was extensive (theta = 0.64). Phylogenetic analysis of A. talpoideum mtDNA sequence reveals a close relationship between the populations from the Central Highlands and the Coastal Plain. This result is similar to that obtained for A. maculatum, although the A. talpoideum clade is not as well differentiated from its sister clades. We discuss the differences and similarities between the two Ambystoma species and previous studies and call for increased focus on multiple species with similar ecologies as a way to detect subtle biogeographic events.     

New species of Septobasidium from southern Costa Rica and the southeastern United States

New species are described in Septobasidium, a genus of urediniomycete parasites on scale insects. One new species, S. gomezii, is described from Costa Rica, and another, S. meredithiae, is described from Louisiana. S. gomezii is most similar to S. septobasidioides, but macroscopic and microscopic differences support it being a distinct species. S. meredithiae is similar to S. alni and S. castaneum but differs from these species in several macroscopic and microscopic characters, especially when the species are observed on the same host tree and insect species. Another species collected only once in Costa Rica is listed with observations but it is not formally described here. This Septobasidium species shares some key characteristics with S. ramorum but combines a dense, compact, nearly black thallus and pigmented probasidia-like structures with spindle-shaped haustoria. Implications for taxonomy, morphological evolution and host specificity in Septobasidium are discussed.     

Role of vegetation in determining carbon sequestration along ecological succession in the southeastern United States

Vegetation plays a central role in controlling terrestrial carbon (C) exchange, but quantifying its impacts on C cycling on time scales of ecological succession is hindered by a lack of long‐term observations. The net ecosystem exchange of carbon (NEE) was measured for several years in adjacent ecosystems that represent distinct phases of ecological succession in the southeastern USA. The experiment was designed to isolate the role of vegetation – apart from climate and soils – in controlling biosphere–atmosphere fluxes of CO₂ and water vapor. NEE was near zero over 5 years at an early successional old‐field ecosystem (OF). However, mean annual NEE was nearly equal, approximately ?450 g C m^?2 yr^?1, at an early successional planted pine forest (PP) and a late successional hardwood forest (HW) due to the sensitivity of the former to drought and ice storm damage. We hypothesize that these observations can be explained by the relationships between gross ecosystem productivity (GEP), ecosystem respiration (RE) and canopy conductance, and long‐term shifts in ecosystem physiology in response to climate to maintain near‐constant ecosystem‐level water‐use efficiency (EWUE). Data support our hypotheses, but future research should examine if GEP and RE are causally related or merely controlled by similar drivers. At successional time scales, GEP and RE observations generally followed predictions from E. P. Odum's ‘Strategy of Ecosystem Development’, with the surprising exception that the relationship between GEP and RE resulted in large NEE at the late successional HW. A practical consequence of this research suggests that plantation forestry may confer no net benefit over the conservation of mature forests for C sequestration.