Sperm competition in horseshoe crabs (Limulus polyphemus)

Male horseshoe crabs have two mating tactics. Some males come ashore attached to a female (clasping the posterior margin of the females' carapace with their modified pedipalps) and nest with her on the intertidal portion of the beach during the high tide. Other males come ashore unattached and crowd around nesting couples. Fertilization is external and unattached males that are in contact with a pair, i.e. satellite males, release sperm, so the assumption has been that they are fertilizing eggs. We conducted a paternity analysis to determine the proportion of eggs fertilized by attached and satellite males. Pairs with one satellite were observed during nesting on beaches in Florida and Delaware and their eggs were collected and reared to the late trilobite or first instar horseshoe crab stage. DNA was extracted from these offspring and from each adult (female, attached and satellite male) for use in paternity analysis. A Limulus-specific hypervariable microsatellite locus was identified and primers were constructed to amplify this locus via the polymerase chain reaction (PCR). Genotypes of putative parents and offspring were determined by resolving length variants of these PCR products on acrylamide gels. This allowed us to determine parentage of the offspring. We demonstrate that satellite males fertilized 40% of the eggs on average, attached males fertilized 51% and 4% of the eggs that were laid by the female were fathered neither by the attached male nor by the satellite (and 5% could not be determined unambiguously). There is high variability in the success of satellite males, ranging from 0 to 88%. Part of this variability can be explained by the position of the satellite relative to the attached male. We discuss the mechanics of fertilization and the possible advantages for multiple mating in this species.     

Preliminary prioritization based on partial order theory and R software for compositional complexes in landscape ecology,with applications to restoration,remediation, and enhancement

The present purpose is to provide convenient computational capability and visualizations for preliminary partial or progressive prioritization based largely on concepts of partial order theory and implemented in R software as illustrated in a context of conservation and sustainable stewardship across landscapes with ecosystem services as a complex multidimensional domain that must be placed in public and private perspective in pursuit of multi-resource management. Practical perspective is promoted by graphic visualization with local partial order modeling (LPOM) methods for screening of settings and scenarios involving interactions of ecosystem elements as evidenced by environmental indicators. ORDIT ordering and precedence plots arise from ascribed advantage as an outcome of a rating regime. Representative ranks constitute criteria drawn from the rank distribution for the case in question. Distal data are determined with regard to remediation and retention. Median mismatches reflect interplay of indicators appearing as isolated instances in plotting patterns. A suggested strategy to circumvent computational constraints is partitioning the pool of cases into collectives by clustering, pursuing classes of partitions, and then prioritizing in particular partitions. When prime prospects have been obtained, detailed determinations can be done with partial ordering procedures involving Hasse diagrams and similarly complex constructs that are difficult to apply with many cases and/or indicator criteria.     

A fiber-optic redox sensor for the iron(III)–iron(II) transition

A phenosafranine-containing Nafion film attached to the distal end of a fiber-optic probe forms a functional redox-sensitive optical sensor. The synthetic cationic photoactive dye phenosafranine, 3,7-diamino-5-phenylphenazinium chloride, responds with changes in light absorbance between its oxidized and reduced forms. This optical property persists when phenosafranine is sorbed into Nafion, a perfluorosulfonate anionic film. Optical properties of the sensor are similar to those seen by others in solution. At high redox conditions, such as an open nitrogen-purged aqueous pH 6.5 solution, optical absorbance of phenosafranine is high, while at low redox conditions, such as an aqueous pH 6.5 iron(II) solution, optical absorbance of phenosafranine is low. Titration of a closed pH 6.5 aqueous solution with a standard iron(II) solution lowers redox potential in a predictable manner and can be followed by the optical redox sensor in parallel with a commercial redox potential electrode.     

Idle emissions from heavy-duty diesel vehicles: review and recent data

Heavy-duty diesel vehicle idling consumes fuel and reduces atmospheric quality, but its restriction cannot simply be proscribed, because cab heat or air-conditioning provides essential driver comfort. A comprehensive tailpipe emissions database to describe idling impacts is not yet available. This paper presents a substantial data set that incorporates results from the West Virginia University transient engine test cell, the E-55/59 Study and the Gasoline/Diesel PM Split Study. It covered 75 heavy-duty diesel engines and trucks, which were divided into two groups: vehicles with mechanical fuel injection (MFI) and vehicles with electronic fuel injection (EFI). Idle emissions of CO, hydrocarbon (HC), oxides of nitrogen (NOx), particulate matter (PM), and carbon dioxide (CO2) have been reported. Idle CO2 emissions allowed the projection of fuel consumption during idling. Test-to-test variations were observed for repeat idle tests on the same vehicle because of measurement variation, accessory loads, and ambient conditions. Vehicles fitted with EFI, on average, emitted approximately 20 g/hr of CO, 6 g/hr of HC, 86 g/hr of NOx, 1 g/hr of PM, and 4636 g/hr of CO2 during idle. MFI equipped vehicles emitted approximately 35 g/hr of CO, 23 g/hr of HC, 48 g/hr of NOx, 4 g/hr of PM, and 4484 g/hr of CO2, on average, during idle. Vehicles with EFI emitted less idle CO, HC, and PM, which could be attributed to the efficient combustion and superior fuel atomization in EFI systems. Idle NOx, however, increased with EFI, which corresponds with the advancing of timing to improve idle combustion. Fuel injection management did not have any effect on CO2 and, hence, fuel consumption. Use of air conditioning without increasing engine speed increased idle CO2, NOx, PM, HC, and fuel consumption by 25% on average. When the engine speed was elevated from 600 to 1100 revolutions per minute, CO2 and NOx emissions and fuel consumption increased by >150%, whereas PM and HC emissions increased by approximately 100% and 70%, respectively. Six Detroit Diesel Corp. (DDC) Series 60 engines in engine test cell were found to emit less CO, NOx, and PM emissions and consumed fuel at only 75% of the level found in the chassis dynamometer data. This is because fan and compressor loads were absent in the engine test cell.     

Method for determining minimum pool requirements to maintain and enhance salmonid fisheries in small Wyoming reservoirs

Methods for determination of minimum pool levels in reservoirs that consider sport fishery values are being sought by managers. We developed a technique for assessing the effects of incremental changes in minimum pool levels on potential salmonid abundance in small (<100 surface hectares at full pool) reservoirs in Wyoming managed for irrigation and municipal water supplies. The method has two components. One component is used to determine the minimum pool level needed to eliminate the risk of overwinter loss of salmonids due to low dissolved oxygen concentrations. The other component predicts the potential biomass of salmonids in reservoirs as a function of water depth and total dissolved solids concentration of the reservoir water. Application of the method is demonstrated for two reservoirs in Wyoming. The unit is jointly supported by the University of Wyoming, the Wyoming Game and Fish Department, and the US Fish and Wildlife Service.     

VOLATILE ORGANIC COMPOUNDS IN GROUND WATER FROM RURAL PRIVATE WELLS, 1986 TO 19991

ABSTRACT: The U.S. Geological Survey (USGS) collected or compiled data on volatile organic compounds (VOCs) in samples of untreated ground water from 1,926 rural private wells during 1986 to 1999. At least one VOC was detected in 12 percent of samples from rural private wells. Individual VOCs were not commonly detected with the seven most frequently detected compounds found in only 1 to 5 percent of samples at or above a concentration of 0.2 microgram per liter (μg/l). An assessment level of 0.2 μg/l was selected so that comparisons of detection frequencies between VOCs could be made. The seven most frequently detected VOCs were: trichloromethane, methyl tert‐butyl ether, tetrachloroethene, dichlorodifluoromethane, methylbenzene, 1,1,1‐trichloroethane, and 1,2‐dibromo‐3‐chloropropane. Solvents and trihalomethanes were the most frequently detected VOC groups in private wells. The distributions of detections of gasoline oxygenates and fumigants seemed to be related to the use patterns of compounds in these groups. Mixtures were a common mode of occurrence of VOCs with one‐quarter of all samples with detections including two or more VOCs. The concentrations of most detected VOCs were relatively small and only 1.4 percent of samples had one or more VOC concentrations that exceeded a federally established drinking water standard or health criterion.