Frequency of sublethal injury in a deepwater ophiuroid, <Emphasis Type="Italic">Ophiacantha bidentata</Emphasis>, an important component of western Atlantic <Emphasis Type="Italic">Lophelia</Emphasis> reef communities

The occurrence and relative abundance of tissue (arm) regeneration in the ophiuroid, Ophiacantha bidentata (Retzius), was examined in individuals collected primarily among colonies of the deep-water coral Lophelia pertusa off the southeastern United States. Seven deep-water coral sites (384–756 m), located between Cape Lookout, NC, and Cape Canaveral, FL, were sampled in June 2004 using a manned submersible. The presence of regenerative tissue was evaluated by visual inspection of each individual ophiuroid, and the proportion of regenerating arms per individual was examined relative to size of individual, geographic location, and depth of collection. Ophiacantha bidentata, the dominant brittle star collected, commonly displayed signs of sublethal injury with over 60% of individuals displaying some evidence of regeneration. These levels of regeneration rival those reported for shallow-water ophiuroids. Larger individuals (>6.5 mm disc size) had a higher incidence of regeneration than smaller individuals. Size of individual and percent of regeneration were negatively correlated with depth. Although O. bidentata was significantly less abundant in southern versus northern sites, ophiuroid abundance did not appear to be influenced by amount or density of coral substratum. Presence of dense aggregations of O. bidentata indicates that they are an important component of the invertebrate assemblage associated with deep-water coral habitat especially in the northern part of the study area. Assuming that observed frequencies of injury and subsequent regeneration represent predation events then dense ophiuroid aggregations in deep-water coral habitats represent an important renewable trophic resource within these communities.     

Controlled release, blind test of DNAPL remediation by ethanol flushing

A dense nonaqueous phase liquid (DNAPL) source zone was established within a sheet-pile isolated cell through a controlled release of perchloroethylene (PCE) to evaluate DNAPL remediation by in-situ cosolvent flushing. Ethanol was used as the cosolvent, and the main remedial mechanism was enhanced dissolution based on the phase behavior of the water-ethanol-PCE system. Based on the knowledge of the actual PCE volume introduced into the cell, it was estimated that 83 L of PCE were present at the start of the test. Over a 40-day period, 64% of the PCE was removed by flushing the cell with an alcohol solution of approximately 70% ethanol and 30% water. High removal efficiencies at the end of the test indicated that more PCE could have been removed had it been possible to continue the demonstration. The ethanol solution extracted from the cell was recycled during the test using activated carbon and air stripping treatment. Both of these treatment processes were successful in removing PCE for recycling purposes, with minimal impact on the ethanol content in the treated fluids. Results from pre- and post-flushing partitioning tracer tests overestimated the treatment performance. However, both of these tracer tests missed significant amounts of the PCE present, likely due to inaccessibility of the PCE. The tracer results suggest that some PCE was inaccessible to the ethanol solution which led to the inefficient PCE removal rates observed. The flux-averaged aqueous PCE concentrations measured in the post-flushing tracer test were reduced by a factor of 3 to 4 in the extraction wells that showed the highest PCE removal compared to those concentrations in the pre-flushing tracer test.     

Native ecotypic variation and the role of host identity in the spread of an invasive herbivore, Cactoblastis cactorum

Environmental niche models (ENMs) have gained enormous popularity as tools to investigate potential changes in species distributions resulting from climate change and species introductions. Despite recognition that species interactions can influence the dynamics of invasion spread, most implementations of ENMs focus on abiotic factors as the sole predictors of potential range limits. Implicit in this approach is the assumption that biotic interactions are relatively unimportant, either because of scaling issues, or because fundamental and realized niches are equivalent in a species' native range. When species are introduced into exotic landscapes, changes in biotic interactions relative to the native range can lead to occupation of different regions of niche space and apparent shifts in physiological tolerances. We use an escaped biological control organism, Cactoblastis cactorum (Berg.), to assess the role of the environmental envelope as compared with patterns of host-herbivore associations based on collections made in the native range. Because all nonnative populations are derived from a single C. cactorum ecotype, we hypothesize that biotic interactions associated with this ecotype are driving the species' invasion dynamics. Environmental niche models constructed from known native populations perform poorly in predicting nonnative distributions of this species, except where there is an overlap in niche space. In contrast, genetic isolation in the native range is concordant with the observed pattern of host use, and strong host association has been noted in nonnative landscapes. Our results support the hypothesis that the apparent shift in niche space from the native to the exotic ranges results from a shift in biotic interactions, and demonstrate the importance of considering biotic interactions in assessing the risk of future spread for species whose native range is highly constrained by biotic interactions.     

Effect of surface incorporation of broiler litter applied to no-till cotton on runoff quality

Surface application of broiler litter to no-till cotton could lead to degradation of water quality. Incorporation of broiler litter into the top surface soil (0.05 m) could alleviate this risk. A 2-yr field study was conducted on a silt loam upland soil to determine the effect of incorporation of broiler litter into the soil surface on nutrient and bacterial transport in runoff. The experimental design was a randomized complete block with four treatments and three replications. Treatments were (i) unfertilized control; (ii) surface-appliedbroiler litter at 7.8 Mg ha(-1) without incorporation; (iii) surface-applied broiler litter at 7.8 Mg ha(-1) with immediate incorporation; and (iv) inorganic fertilizer N (urea ammonium nitrate, 32% N) and inorganic fertilizer P (triple superphosphate) at the recommended rate. Phosphorus was surface appliedat 25 kg ha(-1) and N was injected at 101 kg ha(-1) into the soil using a commercial liquid fertilizer applicator. Runoff was collected from small runoff plots (2.4 m by 1.6 m) established at the bottom side of main plots (13.7 m by 6.0 m). Incorporation of broiler litter reduced total N (TN), NO3-N, water soluble P (WSP), and total P (TP) concentrations in runoffby 35, 25, 61, and 64%, respectively, and litter-associated bacteria by two to three orders of magnitude compared with unincorporated treatment. No significant difference in total suspended solids (TSS) in runoffwas obtained between incorporated and unincorporated treatments. Incorporation of broiler litter into the surface soil in the no-till system immediately after application minimized the potential risk for surface nutrient losses and bacteria transport in runoff.     

Spatial contrasts of seasonal and intraflock broiler litter trace gas emissions, physical and chemical properties

Comprehensive mitigation strategies for gaseous emissions from broiler operations requires knowledge of the litters' physical and chemical properties, gas evolution, bird effects, as well as broiler house management and structure. This research estimated broiler litter surface fluxes for ammonia (NH3), nitrous oxide (N2O), and carbon dioxide (CO2). Ancillary measurements of litter temperature, litter total N, ammonium (NH4+), total C content, moisture, and pH were also made. Grid sampling was imposed over the floor area of two commercial broiler houses at the beginning (Day 1), middle (Day 23), and end (Day 43) of a winter and subsequent summer flock housed on reused pine shavings litter. The grid was composed of 36 points, three locations across the width, and 12 locations down the length of the houses. To observe feeder and waterer (F/W) influences on the parameters, eight additional sample locations were added in a crisscross pattern among these automated supply lines. Color variograms illustrate the nature of parameter changes within each flock and between seasons. Overall trends for the NH3, N2O, and CO2 gas fluxes indicate an increase in magnitude with bird age during a flock for both summer and winter, but flux estimates were reduced in areas where compacted litter (i.e., caked litter or cake) formed at the end of the flocks (at F/W locations and in the fan area). End of flock gas fluxes were estimated at 1040 mg NH3 m(-2) h(-1), 20 mg N2O m(-2) h(-1), and 24,200 mg CO2 m(-2) h(-1) in winter; and 843 mg NH3 m(-2) h(-1), 18 mg N2O m(-2) h(-1)), and 27,200 mg CO2 m(-2) h(-1) in summer. The results of intensive sample efforts during winter and summer flocks, reported visually using contour plots, offer a resource to the poultry industry and researchers for creating new management strategies for improving production and controlling gas evolution. Particularly, efforts could focus on designing housing systems that minimize extremes in litter compaction. The extremes are undesirable with more friable litter prone to greater gas evolution and more compacted litter providing a slippery, disease-sustaining surface.     

Knowledge gain and behavioral change in citizen-science programs

Citizen-science programs are often touted as useful for advancing conservation literacy, scientific knowledge, and increasing scientific-reasoning skills among the public. Guidelines for collaboration among scientists and the public are lacking and the extent to which these citizen-science initiatives change behavior is relatively unstudied. Over two years, we studied 82 participants in a three-day program that included education about non-native invasive plants and collection of data on the occurrence of those plants. Volunteers were given background knowledge about invasive plant ecology and trained on a specific protocol for collecting invasive plant data. They then collected data and later gathered as a group to analyze data and discuss responsible environmental behavior with respect to invasive plants. We tested whether participants without experience in plant identification and with little knowledge of invasive plants increased their knowledge of invasive species ecology, participation increased knowledge of scientific methods, and participation affected behavior. Knowledge of invasive plants increased on average 24%, but participation was insufficient to increase understanding of how scientific research is conducted. Participants reported increased ability to recognize invasive plants and increased awareness of effects of invasive plants on the environment, but this translated into little change in behavior regarding invasive plants. Potential conflicts between scientific goals, educational goals, and the motivation of participants must be considered during program design.     

Chromium transport, oxidation, and adsorption in manganese-coated sand

We examine how the processes of advection, dispersion, oxidation-reduction, and adsorption combine to affect the transport of chromium through columns packed with pyrolusite (beta-MnO2)-coated sand. We find that beta-MnO2 effectively oxidizes Cr(III) to Cr(VI) and that the extent of oxidation is sensitive to changes in pH, pore water velocity, and influent concentrations of Cr(III). Cr(III) oxidation rates, although initially high, decline well before the supply of beta-MnO2 is depleted, suggesting that a reaction product inhibits the conversion of Cr(III) to Cr(VI). Rate-limited reactions govern the weak adsorption of each chromium species, with Cr(III) adsorption varying directly with pH and Cr(VI) adsorption varying inversely with pH. The breakthrough data on chromium transport can be matched closely by calculations of a simple model that accounts for (1) advective-dispersive transport of Cr(III), Cr(VI), and dissolved oxygen, (2) first-order kinetics adsorption of the reduced and oxidized chromium species, and (3) nonlinear rate-limited oxidation of Cr(III) to Cr(VI). Our work supplements the limited database on the transport of redox-sensitive metals in porous media and provides a means for quantifying the coupled processes that contribute to this transport.     

Factors Influencing Prymnesium parvum Population Dynamics During Bloom Initiation: Results from In-lake Mesocosm Experiments1

Roelke, Daniel L., Leslie Schwierzke, Bryan W. Brooks, James P. Grover, Reagan M. Errera, Theodore W. Valenti, Jr., and James L. Pinckney, 2010. Factors Influencing Prymnesium parvum Population Dynamics During Bloom Initiation: Results from In-Lake Mesocosm Experiments. Journal of the American Water Resources Association (JAWRA) 46(1):76-91. DOI: 10.1111/j.1752-1688.2009.00392.x Abstract: The alga Prymnesium parvum forms large fish-killing blooms in many Texas lakes. In some of these lakes, however, P. parvum occurs but does not develop blooms. In this study, we investigated factors that may influence bloom initiation by conducting a series of in-lake experiments involving mixing of waters from Lake Whitney, which has a history of P. parvum blooms, with waters from Lake Waco where no blooms have occurred. In all experiments, the addition of Lake Waco waters resulted in a poorer performance of P. parvum. Various experimental treatments and field data show that differences in grazing, pathogens, nutrients, and salts between the two lakes were not likely factors that contributed to this observation. Industrial and agricultural contaminants, allelochemicals and algicidal chemicals were not measured as a part of this research. However, anthropogenic contaminants other than nutrients were not observed at levels exceeding water quality standards in Lake Waco in recent years. On the other hand, nuisance cyanobacteria are common in Lake Waco, where Microcystis sp. and Anabaena sp. were abundant during the initiation of our experiments, both taxa are known to produce chemicals with allelopathic properties. In addition, the emergent field of algal-heterotrophic bacteria interactions suggests that chemicals produced by heterotrophic bacteria should not be overlooked. Further research focusing on the chemical interactions between cyanobacteria and P. parvum, as well as the potential role of algicidal bacteria, in the initiation of P. parvum blooms is necessary, as it may be important to the management of these blooms.     

Comparison of selected nutrients and bacteria from common contiguous soils inside and outside swine lagoon effluent spray fields after long-term use

Swine (Sus scofa domestica) lagoon effluent is a valuable resource. In the U.S. Mid-South it is applied from April to September to fertilize grass hay in spray-irrigated fields. Lagoon levels of nutrients and bacteria, and soil levels of nutrients have been documented, but little was known of effluent bacterial levels in soil. The present study examined levels of selected effluent bacteria and nutrients in soils inside and outside spray fields after >15 yr of effluent irrigation. Samples were collected February to March 2009 from contiguous soils spanning adjacent irrigated and nonirrigated areas. Separate soil cores for bacterial and nutrient tests were collected in pairs <10 cm apart. Five cores each were collected at 15-m intervals and combined, respectively, to comprise inside and outside samples from each of 20 soils (four each from five farms/spray fields). Analyses of data combined across all soils showed higher pH and Mehlich-3-extracrable (M3-) P, Mg, K, Na, Cu, and Zn inside than outside spray fields, while total N, total C, M3-Ca, and M3-Mn did not differ. Bacterial levels were higher inside than outside spray fields for heterotrophic plate counts, thermotolerant coliforms, Staphylococcus spp., and Clostridium perfringens, but levels of Escherichia coli and Enterococcus spp. were not different. Cultural presence/absence tests for three pathogens (Listeria spp., Campylobacter spp., and Salmonella spp.) detected only Listeria spp., which did not differ inside (23% positive samples) and outside (28% positive). Molecular tests detected all three pathogens at low levels that were not different inside and outside. We found no evidence of cumulative buildup of Campylobacter spp., Listeria spp., or Salmonela s. in spray field soils.     

Estimated occupational risk from bioaerosols generated during land application of class B biosolids

Some speculate that bioaerosols from land application of biosolids pose occupational risks, but few studies have assessed aerosolization of microorganisms from biosolids or estimated occupational risks of infection. This study investigated levels of microorganisms in air immediately downwind of land application operations and estimated occupational risks from aerosolized microorganisms. In all, more than 300 air samples were collected downwind of biosolids application sites at various locations within the United States. Coliform bacteria, coliphages, and heterotrophic plate count (HPC) bacteria were enumerated from air and biosolids at each site. Concentrations of coliforms relative to Salmonella and concentrations of coliphage relative to enteroviruses in biosolids were used, in conjunction with levels of coliforms and coliphages measured in air during this study, to estimate exposure to Salmonella and enteroviruses in air. The HPC bacteria were ubiquitous in air near land application sites whether or not biosolids were being applied, and concentrations were positively correlated to windspeed. Coliform bacteria were detected only when biosolids were being applied to land or loaded into land applicators. Coliphages were detected in few air samples, and only when biosolids were being loaded into land applicators. In general, environmental parameters had little impact on concentrations of microorganisms in air immediately downwind of land application. The method of land application was most correlated to aerosolization. From this large body of data, the occupational risk of infection from bioaerosols was estimated to be 0.78 to 2.1%/yr. Extraordinary exposure scenarios carried an estimated annual risk of infection of up to 34%, with viruses posing the greatest threat. Risks from aerosolized microorganisms at biosolids land application sites appear to be lower than those at wastewater treatment plants, based on previously reported literature.