Declines in annual oyster landings and problems associated with seasonal reduction of oyster meat yields have increased interest for development of techniques to produce oysters with enhanced growth characteristics. Research interest has been focused on developing improved lines by induction of polyploidy. The goal of the present study was to evaluate the enhancement of gonadal development of triploid oysters, by the use of the hormone estradiol 17-â (E2) to produce viable eggs for the development of tetraploid broodstocks. Previous studies with the Pacific oyster, Crassostrea gigas, have shown: (1) the need to use the larger eggs of triploid females to accommodate a tetraploid nucleus, and (2) that E2 appears to be responsible for ovarian maturation. The objective of this research was to compare the effect of three dosages of E2 (0.0, 37.5, 75.0 ng/g wet weight) on ovarian maturation of diploid and triploid eastern oysters, Crassostrea virginica, by measuring: 1) gonad-to-body ratio; 2) oocyte area; 3) levels of E2 in the hemolymph; and, 4) by qualitatively staging gonadal development. Experiments were performed in August of 2003 and May and August of 2004 for 9, 12, and 15 days. Image analysis of histological sections (gonadal condition) and enzyme immunoassays (E2 levels) were used to evaluate the effects of steroidal treatments. There was no evidence of oysters in spawning condition in any of the control groups of the triploid oysters, yet oysters in spawning condition were found in the low and high dose treatments in percentages as high as 40%. For the diploid oysters, the effect of E2 was less apparent due to their natural state of fecundity during the summer months. Concentrations of E2 were measured in diploid and triploid oysters and their levels fluctuated from 13.8 to 29.1 for diploids and from 16 to 33.8 for diploids, with respect to the stage of gonadal maturation. The overall response of triploid oysters to E2 suggested that this hormone had a positive effect on ovarian maturation. These results can have direct applicability for the development of tetraploid broodstocks in the eastern oyster.

In 1994, a 17 yr old, slash pine spacing study was thinned to 35% of the maximum stand density to evaluate the influence of prethinning stand conditions on postthinning growth after thinning to a common stand density. It was expected that plots thinned to a common growing stock level should have equal growth increments and if growth was not equal then the difference was related to prethinning stand conditions. Stand growth variables of quadratic mean diameter increment, stand-level basal area increment, and gross-volume increment were evaluated to determine the influence of initial spacing, stand density, and prethinning crown size before thinning and for 5 years after thinning. Lower values of relative stand densities were associated with initially wider spacings before thinning and higher values 2-5 yr after thinning. Before thinning, quadratic mean diameter increment was positively related to initial spacing and prethinning crown dimensions and negatively related to relative stand density. After thinning, quadratic mean diameter increment was not significantly influenced by initial spacing, but it was inversely correlated with prethinning crown ratio 5 yr after thinning as relative stand density increased. Stand-basal area increment was negatively correlated with prethinning crown width, crown ratio, and crown volume before thinning, but it was not significantly related to initial spacing or relative stand density before or after thinning. Gross-volume increment was positively influenced by initial spacing and prethinning crown dimensions and negatively related to relative stand density prior to thinning. These positive relationships were observed during yr 2, 3, and 4 after thinning where wider initial spacings produced larger increments in volume as relative stand densities increased. Prethinning crown dimensions remained correlated with gross-volume increment after thinning. However, after thinning, these correlations with prethinning crown dimensions held a consistent relation with postthinning growth and also conformed to conventional growth-growing stock relationships as stands developed. The significant relationships detected between gross-volume increment and initial spacing, prethinning crown dimensions, and relative stand densities support that prethinning tree characteristics affected postthinning gross-volume increment for the duration of this study.

Decline of amphibians, reptiles, and numerous Neotropical migrant birds has been attributed to habitat destruction and alteration, which warrants examination of these groups in managed forests and their association with habitat characteristics at multiple spatial scales. We surveyed avifauna and herpetofauna communities in 3 managed forests in Louisiana during 2003-2004. Study areas included Sherburne Wildlife Management Area (WMA), a bottomland hardwood forest under uneven-aged management, Bens Creek WMA, an even-aged, short-rotation loblolly pine plantation, and Sandy Hollow WMA, a longleaf pine-savannah maintained with prescribed fire. Field techniques included surveys consisting of avian point counts, drift fence arrays (PFFT), cover boards, visual encounters, anuran calls (ACS), and microhabitat. We derived landscape variables with GIS landcover maps and ArcView GIS 3.3. General trends included the following: PFFT and ACS accounted for the greatest percentage of detections among herpetofauna surveys, and results primarily reflect these efforts. Anuran calling surveys made a substantial contribution to total number species of detected. Species of conservation concern were among detections of both early- and late-successional bird species. At Sherburne, abundance and richness of amphibians, and occurrence of late-successional birds were greater in uncut and individual-selection stands, whereas occurrence of early-successional birds was greater in recent selection cuttings with groups. Abundance of reptiles did not differ across stand type. At Bens Creek, abundance and richness of anurans was greater in 1-year and 11-23-year stands, whereas abundance and richness of lizards was similar across stand age. Late-successional bird species occurred with greater frequency in 11-23-year stands at Bens Creek, whereas frequency of occurrence of early-successional bird species was greater in 1-year and 4-5-year stands. At Sandy Hollow, abundance of reptiles was greater than amphibians, and occurrence of avifauna was similar to pine-savannah ecosystems elsewhere. Responses to habitat factors at all scales were species specific. In general, canopy closure and shrub cover were the most frequent predictors of occurrence at the microhabitat scale. At the landscape scale, canopy closure and streamside management zones were important predictors of occurrence at Bens Creek, whereas openings and shape complexity of longleaf pine and longleaf savannah were frequent predictors of occurrence at Sandy Hollow. Effects of selection cutting and stand age appear to benefit certain species, including species of conservation concern, but are potentially costly for other species. Efforts to combine management of timber with conservation of amphibians, reptiles, and songbirds must take into consideration both the complexity of habitat requirements of species within these groups and the landscape context in which these requirements occur.

Body size is highly variable among geese, both at intra- and interspecific levels. Interspecific variation in several behaviors has been attributed to differences in body size in geese: incubation constancy, tendency to maintain family units, and time spent foraging. Body size has important physiological implications for birds, mostly because mass-specific metabolic rate is greater for birds of smaller mass. The Body-size Hypothesis predicts that smaller species deplete their energy reserves at relatively faster rates than do larger species. Hypotheses and conclusions concerning effects of body size on waterfowl behavior often are based on comparisons of species that confront different climates, habitat types, and food resources, and migrate variable distances with different energetic costs. Accordingly, I controlled for such variation by comparing the behavior and physiology of lesser snow geese (hereafter snow geese) and Ross's geese, which are closely related and highly sympatric throughout the annual cycle. I found that incubation constancies of both species averaged 99%. The defeathered ventral area was positively related to clutch volume and inversely related to prolactin levels in female Ross's geese, but not in female snow geese; moreover, prolactin levels and body condition were inversely related in Ross's geese, but not in snow geese. I documented that 5 of 5 female snow geese and 1 of 5 female Ross's geese possessed fully-developed brood patches. In winter, I documented that Ross's geese spent more time feeding than did snow geese. All these findings, except that for incubation constancy, were consistent with predictions of the Body-size Hypothesis. Finally, I studied effects of intraspecific body size variation on goose behavior by studying movements and behavior of snow geese in southwest Louisiana. I found that both adult and juvenile snow geese from coastal marshes had larger bodies and bills than did those from rice-prairie habitats. Adult snow geese from coastal marshes spent more time feeding than did those in rice-prairies, whereas the opposite was true for juveniles. I conclude that snow geese in southwest Louisiana segregate into coastal marsh and rice-prairie habitats by body morphometrics, but move too frequently between the 2 habitats to be considered separate populations.

Studies in upland forests of the northeastern and upper mid-western U.S. indicate that high densities of white-tailed deer can reduce vegetation abundance, survival, and richness through over-browsing. In the southern U.S., few studies have examined the effects of deer herbivory on vegetation, and even fewer have done so in forested wetlands. At Jean Lafitte National Park's Barataria Preserve in south Louisiana, managers were concerned that white-tailed deer were concentrating and limiting forest regeneration near a walking trail, where hunting is not allowed. An exclosure study was started there in December 2002 and was conducted through July 2004 to quantify the effects of white-tailed deer on forest regeneration. Differences in densities and heights of naturally occurring tree and woody shrub species > 15 cm but < 200 cm in height were compared between six pairs of fenced and unfenced plots under the forest canopy. Fraxinus pennsylvanica and Quercus nigra juveniles also were planted in these plots, and survival and growth were compared between treatments. Naturally occurring shrub and juvenile tree abundance was compared among plots in treefall gaps and the paired plots under the forest canopy. White-tailed deer decreased the survival of planted Fraxinus pennsylvanica juveniles, but did not affect planted Quercus nigra juveniles or naturally occurring shrubs and juvenile trees. Juvenile trees were ten times more dense in treefall gaps than under the canopy because of the dominance of the exotic Triadica sebifera in gaps. Gap disturbances may be reducing diversity in these coastal wetland forests, rather than promoting diversity as they do in other forests. A more complete understanding of how deer modify the landscape may require future exclosure studies in treefall gaps.

Bottomland hardwood forests and associated fauna, including frogs, are disappearing. The 1990 Farm Bill created a wetland restoration program on private lands called the Wetland Reserve Program (WRP) that has the potential to reverse the declines in species associated with bottomland hardwood forests. As of September 2005, nearly 85,000 ha had been enrolled in Louisiana, but the structure and value of these wetlands to frogs is not known. I evaluated 22 restored and 8 reference wetlands from January through May in 2004 and 2005 to determine the effects of local and landscape scale habitat characteristics on frog species richness and occurrence. I used chorus count surveys, egg mass searches, and dipnet surveys to detect frog species each season. Vegetation characteristics at each wetland were determined seasonally. I evaluated landscape influences by using aerial photography and satellite imagery of the sites to determine the surrounding land use. I used multiple linear and logistic regression analysis and t-tests to evaluate the effects of local and landscape variables on species richness and individual species occurrence. I detected 12 of the 13 species expected to occur. Frog species richness did not differ between restored and natural wetlands, but species richness was higher in 2004 than 2005 (P < 0.0001), presumably due to much greater amounts of rainfall in 2004. Species richness in 2004 was positively influenced by median water depth and canopy cover (P = 0.0011). In 2005, permanent flooding, median water depth, emergent and floating vegetation, and canopy cover positively influenced species richness (P < 0.0001). Species richness also increased with forest in the surrounding landscape. Bullfrogs and bronze frogs were associated with canopy closure, herbaceous vegetation, and nearby forest. Northern cricket frogs were associated with shallow wetlands with floating vegetation, litter, and nearby forest. Gray tree frogs were found in wetlands with canopy cover, low emergent vegetation, and nearby agriculture. Restored wetlands in this study provided suitable frog habitat and supported similar frog species comparable to reference wetlands; however, additional frog and vegetation monitoring should be continued to evaluate restored sites throughout maturation.

I tested the scope of the Spring Condition Hypothesis in explaining the continental population decline of lesser scaup (Aythya affinis; hereafter scaup) and explored potential mechanisms affecting female body condition to assist conservation efforts for population recovery. Lipid reserves of females currently are lower than historical values during spring migration throughout Iowa, Minnesota, and North Dakota; females catabolized lipids throughout this area (indexed by concentrations of plasma-lipid metabolites, which accounted for 75% of the variation in mass change). My results indicate that a large segment of the continental scaup population likely is affected by decreased lipid reserves, which could cause reductions in breeding propensity and reproductive success. Hepatic cadmium was negatively correlated with lipid reserves of females during spring migration; however, current cadmium concentrations only accounted for 11% of the observed decrease in lipid reserves of females between Illinois and Minnesota. Wetland use by scaup was positively correlated with amphipod densities throughout the upper-Midwest, indicating a preference for amphipods. Amphipod densities were markedly lower (1 - 12 m^-3) and scaup were consuming fewer amphipods in the upper-Midwest relative to historical records. Scaup probably must spend more time searching for food within and among wetlands than they did historically. Fish occurred in 74, 78 - 84, and 31 - 45% of wetlands in Iowa, Minnesota, and North Dakota, respectively, whereas historically they occurred in only 10 - 20% of wetlands. Amphipod densities were negatively correlated to fish densities and sedimentation. My results indicate that there has been a decrease in amphipod densities throughout the upper-Midwest, which likely is causing the observed decreases in lipid reserves of scaup. My results generally were consistent with the Spring Condition Hypothesis and indicate that wetland restoration efforts are needed throughout the upper-Midwest, but especially in Iowa and southern Minnesota. Managers should provide abundant populations of amphipods (over 26 m^-3 geometric mean across the landscape) and target wetlands that: (1) have large (> 500 m diameter) open-water zones, (2) are deep enough to support over-wintering populations of amphipods, (3) allow management of fish communities, and (4) the surrounding land can be managed to reduce sedimentation.

A variety of techniques have been employed in attempts to mitigate the extensive wetland loss occurring in coastal Louisiana. Marsh terracing is a wetland restoration technique that has rapidly gained in popularity in recent years. Terraces are assumed to benefit coastal restoration by providing areas for emergent plant growth, reducing wave energies, and increasing edge habitat to support nekton communities. The objectives of this study were to: 1) determine the effect of marsh terraces on adjacent water quality and sediment characteristics, 2) compare nekton abundance, species richness, and diversity in edge and open water habitats within terraced and unterraced ponds, and 3) compare the condition of numerically dominant fishes between terraced and unterraced ponds as an indicator of habitat quality. Three study sites located in southwest Louisiana at Sabine National Wildlife Refuge and Rockefeller State Wildlife Refuge were selected for the study. Each study site consisted of a terraced pond and a nearby unterraced reference pond. Nekton was quantitatively sampled in four different habitat types at each study site with a 1-m² throw trap. The habitat types sampled were: 1) terraced marsh edge, 2) unterraced marsh edge, 3) open water within terraced ponds, and 4) open water within unterraced ponds. Nekton density (P = 0.0004), biomass (P = 0.002), species richness (P = 0.0007), and diversity (H', P = 0.01) (1-D, P = 0.007) were all significantly greater at terraced edge habitats (treatment) as compared to unterraced open water habitats (control). There was no significant difference in these variables between terraced and unterraced edge habitats. While terraced pond habitats were superior to pre-restoration conditions in terms of nekton habitat value, they lacked functional equivalency with comparable unterraced ponds in several areas: 1) nekton community composition differed between terraced and unterraced edge habitats, and 2) several fish species were found to be in poorer condition in terraced ponds as compared to unterraced ponds. A lack of functional equivalency between terraced and unterraced habitats may be partially attributable to the relatively young age of the terraces studied, as many functions of created marshes may take years to develop.

Impacts red imported fire ants (RIFA) exert on native faunal communities were monitored in two pine-dominated ecosystems in Louisiana. After suppression of established RIFA populations with Amdro®, cotton mice (Peromyscus gossypinus), herpetofaunal, ground-dwelling invertebrate, Lycosidae, and non-target ant communities were compared between untreated-control and treated plots with respect to possible ecological impacts of RIFA on these communities. Efficacy of Amdro® (A. I. 0.7% hydramethylnon) was tested at Alexander State Forest and Sandy Hollow WMA, and was found to be effective at both sites for 99-42.3% and 97-48%, respectively, suppression of RIFA on treated plots, for three to seven months, with treatments administered in the evening at a rate 1.68 kg/ha. Following suppression, RIFA were shown to minimally impact cotton mice, ground-dwelling invertebrate populations, and Lycosidae species, indicating that RIFA is not the regulating factor in these communities. In the case of cotton mice, habitat conditions that favor cotton mice may also favor RIFA. The majority of non-target ants analyzed at Alexander State Forest and Sandy Hollow WMA also seem to coexist with RIFA, although some species including Aphaenogaster rudis-texana, Crematogaster lineolata, Brachymrymex musculus, Paratrechina faisonensis, Pheidole dentata, and Pheidole metallescens may occur in sparse, small populations in the presence of RIFA. At Alexander State Forest, both Brachymrymex musculus and Tapinoma sessile showed a positive response to RIFA suppression, indicating signs of competitive release. At Sandy Hollow WMA Monomorium minimum and Prenolepis imparis responded negatively to treatment, indicating that Amdro® may exhibit non-target effects to these two species. Herpetofaunal communities, particularly ground skink and southeastern five-lined skink populations may be negatively impacted by RIFA. However sample sizes for all herpetofauna species were low. Amdro® is effective at suppressing RIFA populations in forested ecosystems; however the impacts RIFA pose on native ground-dwelling faunal communities may be minimal in these two pine-dominated communities.

Tropical forests, which contain 50 percent of the planet's biodiversity, are threatened by deforestation and illegal logging. Forest certification was initiated initially as a s certification: forest management practices and chain of custody (CoC). The United States is the largest market for secondary, or value-added, tropical hardwood products (STHP) which influences forest management practices in supplier countries. In 2004, this study was conducted to measure the demand for certified products in the U.S. The objectives of the study were to identify characteristics of U.S. demand for secondary (value-added) tropical hardwood products and to understand market perceptions regarding certification of secondary tropical hardwood products. Two sectors were surveyed: importers / brokers / manufacturers / wholesalers / retailers (Supply Chain) and builders and architects (B&A). Response rates were 19 percent for Supply Chain and 12 percent for B&A. For both groups, brokers and wholesalers are the dominant purchase channels for tropical hardwoods. More than 50 percent of TSHP originates from South America with Brazil being the primary export country. The main TSHP imported are doors, flooring, cabinets, and millwork. The most important criteria for respondents when selecting tropical hardwoods are quality, availability, and performance. Consistent supply is the greatest barrier to purchasing TSHP. With regard to certified tropical value-added hardwoods, generally respondents do not pay premiums relative to non-certified alternatives. Certification is not an important product selection attribute relative to price and quality. The B&A respondent group experienced more unexpected costs relative to Supply Chain members while Supply Chain members are more likely to promote certified product to their customers. Overall, in order to target the U.S. market tropical hardwood suppliers, particularly those that are engaged in certification, need to improve consistency of their supply and ensure that product quality standards remain at or above non-certified alternatives.