Influence of an insect growth regulator on the larval development of an estuarine shrimp

The influence of methoprene, an insect growth regulator used in mosquito control, on larval development of the estuarine grass shrimp (Palaemonetes pugio) was examined in the laboratory. No grass shrimp larvae successfully completed metamorphosis when continuously exposed to 1000 microg methoprene litre(-1). Completion of larval metamorphosis was significantly reduced by exposure to 100 microg litre(-1) of the isomeric mixture (R,S)-methoprene but not the single isomer formulation (S)-methoprene. No statistically significant difference was revealed, however, in ability to inhibit metamorphosis between these two isomeric types across the broad range of exposure concentrations from 0.1 to 1000.0 microg litre(-1). The first two larval stages and the final premetamorphic larval stage were more sensitive to methoprene toxicity than intermediate larval stages. Methoprene exposure did not alter either the duration of total larval development or the total number of larval stages prior to metamorphosis.     

Comparison of the 1-hr and 8-hr National Ambient Air Quality Standards for ozone using Models-3

In 1997, the U.S. Environmental Protection Agency revised the National Ambient Air Quality Standard governing ozone (O3), adding an 8-hr standard of 0.08 ppm and phasing out the 1-hr requirement of 0.12 ppm. The 8-hr standard is intended to provide greater protection for human health. This research examines spatial and temporal patterns of exceedances of the standards using monitoring data and modeled estimates. The Penn State/National Center for Atmospheric Research Mesoscale Model and Models-3 framework were used to estimate hourly O3 concentrations for 4-km resolution in the Maryland/Virginia/Delaware/Washington, DC, and northern Georgia domains. Results reveal that the spatial and temporal nature of compliance is considerably different under the 8-hr standard. In the modeling simulations, the 8-hr standard was exceeded 2-5.2 times more often and in a 1.8-16.2 times larger area than the 1-hr standard. The 8-hr standard was exceeded in areas that generally comply with the 1-hr standard and are not well covered by the monitoring network. These results imply that a larger population resides in areas with unhealthy O3 levels than noncompliance with the original 1-hr standard suggests. For the MD/VA/DE/DC domains, 80 and 98% of the total population live in areas with 8-hr National Ambient Air Quality Standards (NAAQS) exceedances for the 1990 and 1995 episodes, respectively.     

Predicting invasion risk using measures of introduction effort and environmental niche models.

The Chinese mitten crab (Eriocheir sinensis) is native to east Asia, is established throughout Europe, and is introduced but geographically restricted in North America. We developed and compared two separate environmental niche models using genetic algorithm for rule set prediction (GARP) and mitten crab occurrences in Asia and Europe to predict the species' potential distribution in North America. Since mitten crabs must reproduce in water with >15% per hundred salinity, we limited the potential North American range to freshwater habitats within the highest documented dispersal distance (1260 km) and a more restricted dispersal limit (354 km) from the sea. Applying the higher dispersal distance, both models predicted the lower Great Lakes, most of the eastern seaboard, the Gulf of Mexico and southern extent of the Mississippi River watershed, and the Pacific northwest as suitable environment for mitten crabs, but environmental match for southern states (below 35 degrees N) was much lower for the European model. Use of the lower range with both models reduced the expected range, especially in the Great Lakes, Mississippi drainage, and inland areas of the Pacific Northwest. To estimate the risk of introduction of mitten crabs, the amount of reported ballast water discharge into major United States ports from regions in Asia and Europe with established mitten crab populations was used as an index of introduction effort. Relative risk of invasion was estimated based on a combination of environmental match and volume of unexchanged ballast water received (July 1999-December 2003) for major ports. The ports of Norfolk and Baltimore were most vulnerable to invasion and establishment, making Chesapeake Bay the most likely location to be invaded by mitten crabs in the United States. The next highest risk was predicted for Portland, Oregon. Interestingly, the port of Los Angeles/Long Beach, which has a large shipping volume, had a low risk of invasion. Ports such as Jacksonville, Florida, had a medium risk owing to small shipping volume but high environmental match. This study illustrates that the combination of environmental niche- and vector-based models can provide managers with more precise estimates of invasion risk than can either of these approaches alone.     

Potential effects of climate change on birds of the Northeast

We used three approaches to assess potential effects of climate change on birds of the Northeast. First, we created distribution and abundance models for common bird species using climate, elevation, and tree species variables and modeled how bird distributions might change as habitats shift. Second, we assessed potential effects on high-elevation birds, especially Bicknell’s thrush (Catharus bicknelli), that may be particularly vulnerable to climate change, by using statistical associations between climate, spruce-fir forest vegetation and bird survey data. Last, we complemented these projections with an assessment of how habitat quality of a migratory songbird, the black-throated blue warbler (Dendroica caerulescens) might be affected by climate change. Large changes in bird communities of the Northeast are likely to result from climate change, and these changes will be most dramatic under a scenario of continued high emissions. Indeed, high-elevation bird species may currently be at the threshold of critical change with as little as 1°C warming reducing suitable habitat by more than half. Species at mid elevations are likely to experience declines in habitat quality that could affect demography. Although not all species will be affected adversely, some of the Northeast’s iconic species, such as common loon and black-capped chickadee, and some of its most abundant species, including several neotropical migrants, are projected to decline significantly in abundance under all climate change scenarios. No clear mitigation strategies are apparent, as shifts in species’ abundances and ranges will occur across all habitat types and for species with widely differing ecologies.     

Modeling potential climate change impacts on the trees of the northeastern United States

We evaluated 134 tree species from the eastern United States for potential response to several scenarios of climate change, and summarized those responses for nine northeastern United States. We modeled and mapped each species individually and show current and potential future distributions for two emission scenarios (A1fi [higher emission] and B1 [lower emission]) and three climate models: the Parallel Climate, the Hadley CM3, and the Geophysical Fluid Dynamics Laboratory model. Climate change could have large impacts on suitable habitat for tree species in this region, especially under a high emissions trajectory. Results indicate that while species with potentially increasing areas of suitable habitat in the Northeastern US substantially outnumber those with decreasing areas of habitat, there are key species that show diminishing habitat area: balsam fir (Abies balsamea), paper birch (Betula papyrifera), red spruce (Picea rubens), bigtooth and quaking aspen (Populus grandidentata and P. tremuloides), and black cherry (Prunus serotina). From these results we identified the top 10 losers and gainers for each US state in the region by scenario and emissions trajectory. By combining individual species importance maps and developing assembly rules for various classes, we created maps of potential forest types for the Northeast showing a general loss of the spruce–fir zone with advancing oak–hickory type. Further data, maps, and analysis can be found at http://www.nrs.fs.fed.us/atlas.     

Sexual behavior among parasitic Megarhyssa wasps (Hymenoptera: Ichneumonidae)

Summary Male wasps of three sympatric species of Nearctic Megarhyssa (Hymenoptera: Ichneumonidae) typically form mixed-species (61.7%) aggregations composed of up to 28 males over sites of female emergence. Observations of 107 aggregations over two seasons in New York state revealed two male mating strategies: postemergence copulation on the tree surface and preemergence insemination accomplished by male abdominal insertion into the female emergence hole. Insertions by one or more males (as many as ten consecutively but not more than two simultaneously) occurred at 88% of the aggregations, with each inserting for an average of 24.8 min. Insemination as a result of preemergence insertion had a success rate of 83% while postemergence copulation attempts were successful 30% of the time (average duration 61.9 s). Individual male reproductive success was very low and not correlated with size, arrival order at emergence sites, or tenacity at the site. Males frequently aggregated at sites of male emergences as well as those of nonconspecifics, though conspecifics to the emerger ultimately played the major role at aggregations. Male-male aggression in aggregations was not apparent, though jostling occurred during the insertion period and during postemergence copulation attempts.     

A comparison of the social organization of three syntopic species of Australian thornbill,Acanthiza

Summary Brown (Acanthiza pusilla), buff-rumped (A. reguloides) and striated thronbills (A. lineata) were studied over three years in eucalypt forest in northern New South Wales. All three are small, sexually monomorphic insectivores. A. pusilla is a shrub-feeder, reguloides a bark and ground forager and lineata gleans from eucalypt leaves. A. reguloides and lineata show a two-tiered social organization with territorial clans in the non-breeding season which split up into breeding pairs or groups of 3 or 4. Non-breeding birds feed nestlings and fledglings, and after reformation of the clan adults feed fledglings belonging to other groups. Females tend to disperse more than males before the next breeding season, males tend to stay and help. A. pusilla breeds in pairs, with no helpers, defends year-round territories and expels juveniles a few months after they fledge. We discuss possible reasons why A. pusilla is not cooperative whereas the other two species are. It seems not to be due to greater adult survival and habitat saturation in the latter two, nor to reduced seasonal fluctuations in food. We propose that a major factor is the low risk of dispersing relative to staying at home in pusilla compared with the other two species.     

Honest begging in the blue-footed booby: signaling food deprivation and body condition

To determine whether solicitation by blue-footed booby chicks accurately encodes their need for food, we independently manipulated the body condition and recent food ingestion of singleton chicks and recorded three measures of begging. Variations in the three measures of begging covaried only partially, but in general, chicks begged more intensely when they were in poor body condition and also when suffering recent food deprivation. Effects of body condition and recent food deprivation on begging were broadly additive, although deprived chicks in poor condition failed to beg more intensely than those in good condition. Protracted short-term deprivation may create such a high level of need that the body condition component of need becomes temporarily unimportant. Parents more frequently fed chicks that begged more intensely, chicks in poor condition, and chicks suffering food deprivation. Deprived chicks in poor condition received more food than deprived chicks in normal condition even though they did not beg more intensely, possibly because parents responded not only to current begging but also to begging earlier in the day, or to other cues to body condition. These results support the hypothesis that begging of boobies represents honest signaling of need.     

Fenarimol solar degradation pathways and photoproducts in aqueous solution

The degradation photoproducts of the fungicide fenarimol obtained from irradiation of aqueous solutions with sunlight were characterised. The photoproducts resulting from samples with different exposure times were extracted and separated using chromatographic techniques. Seven main photoproducts were detected using high performance liquid chromatography with a photodiode array detector, gas chromatography with mass spectrometry detector and Fourier transform infrared spectroscopy. Structures are suggested for possible photoproducts based on the characterisation results, minimum energy geometry of the parent compound, and the mass spectral behaviour of fenarimol. These correspond to the compounds with m/z 328 (three structural isomers (a), (b) and (c)), m/z 294 (two structural isomers (a) and (b)), m/z 292, 278 and 190. Of the various major products detected, the isomer 328(a) is seen to be particularly unstable under the action of sunlight. The most stable photoproducts are found to be those with m/z 294(a), 278 and 190. However, upon prolonged solar irradiation all of these break down to produce polar, low molecular weight compounds. Comparison with our own and other results on fenarimol photolysis indicate significant solvent effects on the process. The combination of these structural characterisation results and previous data from spectroscopic and photodegradation kinetics studies allows us to suggest some possible mechanisms for the photodegradation of fenarimol under sunlight.     

The impact of climate change on the soil/moisture regime of Scottish mineral soils

The likely impact of climate change on the moisture regime of Scottish soils and consequently on agriculture and land use has been addressed using a novel Geographic Information Systems (GIS) approach. Current estimates of changes in summer precipitation by the year 2030 are 0% with an associated uncertainty of +/- 11%. This study considers the worst case scenario of a decrease in rainfall by 11% which will lead to some low rainfall areas experiencing an increased drought risk, particularly on lighter soils. Wet areas with heavy soils could benefit from an increase in the accessibility period for machinery. As the major agricultural land in Scotland is located on the relatively dry east coast where localised problems due to drought are not uncommon even under the present climate, the detrimental effects of a decrease in rainfall for the whole of Scotland are therefore likely to outweigh the benefits. Approximately 8% of Scotland has been identified in this study as soil/climate combinations which will be susceptible to drought should summer rainfall decrease by 11% and summer temperature increase by 1.4 degrees C.