Feeding,conversion efficiencies,and growth of larval mummichogs,Fundulus heteroclitus

Feeding rates, conversion efficiencies and growth of larvae of the mummichog Fundulus heteroclitus, an extremely abundant estuarine fish, were measured at temperatures ranging from 18° to 30°C. The food used was Artemia salina nauplii. At the time of total yolk sac absorption (5 to 7 days after hatching), the feeding rate decreased for a short time, an indication of a shift in metabolism. Higher feeding rates and growth occurred at higher rearing temperatures. The highest conversion efficiency (gross growth efficiency) was 1.1%, at 22°C. Mummichog larvae may be energetically inefficient compared with other fish species, but efficiency might not be critical for this fish, which is an opportunistic omnivore in an energy-rich environment.Contribution No. 291 of the Belle W. Baruch Institute for Marine Biology and Coastal Research, supported by DOE contract No. EY-76-5-09-0869.     

Monolignol biosynthesis and genetic engineering of lignin in trees, a review

This paper summarizes our previous and current research on genetic engineering of lignin biosynthesis for the purposes of improving wood pulping and bleaching efficiency. For these purposes, our targets were to produce transgenic trees with low content of lignin that is also chemically reactive (high lignin S/G ratio). Using aspen as a model species, we have characterized the biochemical functions of various genes and the kinetic properties of these gene products involved in monolignol biosynthetic pathway. The results of these characterizations proved strong evidence for a principle phenolic flux leading to the formation of monolignols. Biochemical evidence further demonstrated that, in this principle flux, 4CL could be the enzyme limiting total lignin accumulation, whereas CAld5H might control the lignin S/G ratio. These propositions were fully supported by the in vivo functions of these enzymes. Transgenic trees with inhibited 4CL enzyme activity exhibited 5–45% reduction in lignin contents. The chemical structure of the resulting lignin remained essentially unchanged. More importantly, the lignin reduction was compensated for by a concomitant increase in cellulose content. When antisense 4CL and sense coniferaldehyde 5-hydroxylase (CAld5H) genes were simultaneously transferred into aspen via Agrobacterium, transgenic trees expressing each one and both of the transgenes were produced. Lignin reductions up to 55% were achieved in antisense 4CL plants and up to 3-fold S/G increases were observed in sense CAld5H plants. These effects were independent but additive, with plants expressing both transgenes having less lignin and higher S/G ratio. Consistent with our previous results, lignin reduction has always resulted in an increase in cellulose content. These transgenics could be potentially valuable for pulp production. But more importantly, these benchmark transgenics are rich sources of information for functional genomics and metabolic engineering, allowing the generation of the ultimate raw materials for wood pulp production.     

Changes in the grassland-forest boundary at Ta-Ta-Chia long term ecological research (LTER) site detected by stable isotope ratios of soil organic matter

The carbon isotope analysis [delta13C values] of organic samples can be a useful research in ecological studies because delta13C values are indicative of the plant source. This study investigated the changes in plant communities along the grassland-forest boundary in the alpine forest at Ta-Ta-Chia long term ecological research (LTER) site in central Taiwan using carbon isotope data. The aim of this study was focused on the forest fire affected the change of vegetation community. Four pedons from grassland dominated by Miscanthus transmorrisonensis (pedons 1 and 2), transition zone by Tsuga and Yushania nittakeyamensis (pedon 3), and forest zone by Tsuga and nittakeyamensis (pedon 4) were examined. Soil organic matter (SOM) delta13C values in the upper soil horizon were similar to delta13C values of the overlaying vegetation types. This indicates that the boundary between these plant communities remained the same in the past decades. The delta13C values of the grassland SOM ranged from -19.4 per thousand to -24.1 per thousand, showing decrease with soil depth. This suggests that C4 plants (transmorrisonensis) have replaced C3 plants of Tsuga and nittakeyamensis. The delta13C values of the Tsuga forest area (pedon 4) range from -27.0 per thousand to -23.5 per thousand and showed only slight change with soil depth, implying that C3 plants have remained the major species in the forest.     

Pyrolysis kinetics and residue characteristics of petrochemical industrial sludge

This study investigated the pyrolysis characteristics of sludge from wastewater treatment plants in the petrochemical industry and focused on the pyrolysis kinetics, elemental composition of residue, and volatile organic compounds (VOCs) of exhaust gas. As pyrolysis temperature increased to 773 K, the increasing rate of crude oil production tended to a stable condition. The result indicated that the optimal temperature of crude oil and water mixed production was 773 K. When pyrolysis temperature increased from 673 to 973 K, carbon, oxygen, nitrogen, and hydrogen concentrations of residue decreased and the sulfur concentration of residue increased. The concentrations of benzene, toluene,ethylbenzene, and styrene increased by the increasing pyrolysis temperature. We found that the reaction order of sludge pyrolysis was 2.5 and the activation energy of the reaction was 11.06 kJ/mol. We believe that our pyrolysis system is transitional between devolatilization and combustion.     

Impact of acid mine drainage on benthic communities in streams: the relative roles of substratum vs. aqueous effects

Restoration of streams impacted by acid mine drainage (AMD) focuses on improving water quality, however precipitates of metals on the substrata can remain and adversely affect the benthos. To examine the effects of AMD precipitates independently of aqueous effects, four substrata treatments, clean sandstone, clean limestone, AMD precipitate-coated sandstone and coated limestone, were placed in a circumneutral stream of high water quality for 4 weeks. Iron and Al were the most abundant metals on rocks with AMD precipitate. and significantly decreased after the exposure. Precipitate on the substrata did not significantly affect macroinvertebrate or periphyton density and species composition. In an additional experiment, percent survival of caged live caddisflies was significantly lower when exposed in situ for 5 days in an AMD affected stream than in a reference stream. Caddisfly whole-body concentrations of all combined metals and Fe alone were significantly higher in the AMD stream. Whole-body metal concentrations were higher in killed caddisflies than in live, indicating the importance of passive uptake. The results suggest the aqueous chemical environment of AMD had a greater affect on organisms than a coating of recent AMD precipitate on the substrata (ca. 0.5 mm thick), and treatment that improves water quality in AMD impacted streams has the potential to aid in recovery of the abiotic and biotic benthic environment.     

Is Mutation Accumulation a Threat to the Survival of Endangered Populations?

The accumulation of new deleterious mutations has been predicted to constitute a significant threat to the survival of finite sexually reproducing populations. Three measures of genetic load were made on populations of Drosophila melanogaster maintained at effective population sizes of 25, 50, 100, 250, and 500 for 45 or 50 generations and their outbred base population and a new sample from the same wild population. Genetic loads were measured as fitness differentials between inbred and non-inbred lines derived from each population under both benign ( productivity of single pairs) and competitive (competitive index) conditions. No trend of smaller populations exhibiting greater genetic loads than larger ones was observed under either benign or competitive conditions. Further, genetic loads were similar in captive and wild populations. Frequencies of deleterious and lethal alleles on chromosome II were measured by making the chromosome (approximately 40% of the genome) homozygous using a marked balancer stock. Neither deleterious nor lethal allele frequencies exhibited a relationship with population size. The accumulation of detrimental mutations does not appear to pose a significant threat to finite sexual populations with effective sizes of 25 or more over the 100–200 year time frames considered in most wildlife conservation programs.     

Experimental studies on elimination of zinc-65, cesium-137 and cerium-144 by euphausiids

The elimination of 3 radionuclides from Euphausia pacifica was measured over a 5 month period. The biological half-lives for ⁶⁵Zn, ¹³⁷Cs, and ¹⁴⁴Ce, calculated after the euphausiids had ingested radioactive Artemia nauplii, were found to be 140 days, 6 days, and 7.5 h, respectively. The percentages of body burdens lost in molts were greatest for the fission products, ¹⁴⁴Ce (21%) and ¹³⁷Cs (7%), and least for ⁶⁵Zn (1%). Elimination of the isotopes in the feces could not be followed because of the difficulty in collecting fecal material for analysis; however, 1 sample collected 2 months after the beginning of the elimination experiment had no measurable radioactivity. Loss of ⁶⁵Zn from molts and time to disintegration of the molts were found to be temperature dependent over a 5° to 15°C range, and the sinking rate of molts was both temperature and salinity dependent. Calculations showed that, in areas in the North Pacific outside the influence of upwelling, percentage ⁶⁵Zn loss from sinking molts (before disintegration of the molts) was likely to be the same throughout the year, since the molts would be exposed to about the same mean temperature in the water column in all seasons. Even though temperature structure in the upper layers changes with season, mean temperatures change very little when calculated over the sinking distance of intact molts. Intact molts would sink to slightly over 400 m in the absence of turbulence, and would lose 87% of their ⁶⁵Zn by the time they reached this depth. Sinking molts thus might contribute substantially to the vertical transport of ⁶⁵Zn in the sea. If loss of ⁶⁵Zn in fecal pellets is assumed to be small under our experimental conditions, and molting loss is only 1% of ⁶⁵Zn body burden, the major mechanism of ⁶⁵Zn loss from euphausiids feeding on non-radioactive food must be isotopic exchange with the water. Approximately 96% of the initial body burden was eliminated over a period of 5 months.Supported by USAEC research contract AT (45-1)1830, PHS grant ES00026, and a Richland Graduate Fellowship to S. W. Fowler.     

Evidence for seasonal mate limitation in populations of an intertidal amphipod, Corophium volutator (Pallas)

Potential rates of reproduction (PRR) differ between the sexes of many animal species. Adult sex ratios together with PRR are expected to determine the operational sex ratio (OSR) defined as the ratio of fertilizable females to sexually active males at any given time. OSR is expected to determine the degree to which one sex competes for another—the limiting sex. We explored the potential for mate limitation in an intertidal amphipod, Corophium volutator (Pallas). Males have higher PRR than females, but males may be limiting because of extreme female-biased sex ratios observed in this species. Consistent with this idea, late season females were less likely to be ovigerous and had smaller size-specific clutches, both of which were associated with seasonal declines in availability of males of reproductive size. Seasonal changes in ovigery could not be explained by seasonal changes across sites in other factors (e.g., female body size or phenology of breeding). Smaller females were less likely to become ovigerous later in the season at three of four sites. Seasonal reductions in clutch size also occurred among small females expected to be reproducing for their first time. In complimentary laboratory experiments, reduced likelihood of ovigery and reduced fecundity occurred when the number of receptive females was increased relative to availability of a reproductively active male. Our results suggest male mate limitation can occur seasonally in this species and that male limitation is regionally widespread and may affect recruitment.     

Town-scale microbial sewer community and H2S emissions response to common chemical and biological dosing treatments

Controlling hydrogen sulfide (H₂S) odors and emissions using a single, effective treatment across a town-scale sewer network is a challenge faced by many water utilities. Implementation of a sewer diversion provided the opportunity to compare the effectiveness of magnesium hydroxide (Mg(OH)₂) and two biological dosing compounds (Bioproducts A and B), with different modes of action (MOA), in a field-test across a large sewer network. Mg(OH)₂ increases sewer pH allowing suppression of H₂S release into the sewer environment while Bioproduct A acts to disrupt microbial communication through quorum sensing (QS), reducing biofilm integrity. Bioproduct B reduces H₂S odors by scouring the sewer of fats, oils and grease (FOGs), which provide adhesion points for the microbial biofilm. Results revealed that only Mg(OH)₂ altered the microbial community structure and reduced H₂S emissions in a live sewer system, whilst Bioproducts A and B did not reduce H₂S emissions or have an observable effect on the composition of the microbial community at the dosed site. Study results recommend in situ testing of dosing treatments before implementation across an operational system.     

Practical Perspectives of 1,4‐Dioxane Investigation and Remediation

1,4‐Dioxane (dioxane) is a contaminant of emerging concern that is classified by the U.S. Environmental Protection Agency as a likely human carcinogen. Dioxane has been used as a minor or major ingredient in many applications, and is also generated as an unwanted by‐product of industrial processes associated with the manufacturing of polyethylene, nonionic surfactants, and many consumer products (cosmetics, laundry detergents, shampoos, etc.). Dioxane is also a known stabilizer of chlorinated solvents, particularly 1,1,1‐trichloroethane, and has been commonly found comingled with chlorinated solvent plumes. Dioxane plumes at chlorinated solvent sites can complicate site closure strategies, which to date have not typically focused on dioxane. Aggressive treatment technologies have greatly advanced and are clearly capable of achieving lower parts per billion cleanup criteria using ex situ advanced oxidation processes and sorption media. In situ chemical oxidation has also been demonstrated to effectively remediate dioxane and chlorinated solvents. Other in situ remedies, such as enhanced bioremediation, phytoremediation, and monitored natural attenuation, have been studied; however, their ability to achieve cleanup levels is still somewhat questionable and is limited by co‐occurring contaminants. This article summarizes and provides practical perspectives on dioxane analysis, plume stability relative to other contaminants, and the development of investigation tools and treatment technologies.