The icy Galilean satellites: ultraviolet phase curve analysis

Ultraviolet disk-integrated solar phase curves of the icy galilean satellites Europa, Ganymede, and Callisto are presented, using combined data sets from the International Ultraviolet Explorer (IUE), Hubble Space Telescope (HST), and the Galileo Ultraviolet Spectrometer. Global, disk-integrated solar phase curves for all three satellites, in addition to disk-integrated solar phase curves for Europa's leading, trailing, jovian, and anti-jovian hemispheres, are modeled using Hapke's equations for 7 broadband UV wavelengths between 260 and 320 nm. The sparse coverage in solar phase angle, particularly for Ganymede and Callisto, and the noise in the data sets poorly constrain some of the photometric parameter values in the model. However, the results are sufficient for forming a preliminary relationship between the effects of particle bombardment on icy surfaces and photometric scattering properties at ultraviolet wavelengths. Callisto exhibits a large UV opposition surge and a surface comprised of relatively low-backward scattering particles. Europa's surface displays a dichotomy between the jovian and anti-jovian hemispheres (the anti-jovian hemisphere is more backward scattering), while a less pronounced hemispherical variation was detected between the leading and trailing hemispheres. Europa's surface, with the exception of the trailing hemisphere region, appears to have become less backscattering between the late-1970s-early-1980s and the mid-1990s. These results are commensurate with the bombardment history of these surfaces by magnetospheric charged particles.     

Vesta’s UV lightcurve: hemispheric variationin brightness and spectral reversal

Spectra of asteroid 4 Vesta obtained in October 1990 with the International Ultraviolet Explorer are reanalyzed and reinterpreted. A large portion of the eastern hemisphere (based on the prime meridian definition of Thomas et al., 1997a) is darker at UV wavelengths than much of the western hemisphere. The UV lightcurve is in contrast with the visible lightcurve, which shows that the eastern hemisphere is brighter than the western. These IUE spectra of Vesta thus may be evidence for the “spectral reversal,” first seen on the Moon by Apollo 17, where the visibly brighter lunar highlands are darker than the maria at far-UV wavelengths. This effect was linked to space weathering when it was noted (Wagner et al., 1987) that the spectral reversal appears in the laboratory spectra of lunar soils but not powdered lunar rocks.We investigate Vesta’s UV lightcurve and spectral reversal, and its possible connection with space weathering. The addition to grain coatings of small amounts of submicroscopic iron (SMFe) through vapor deposition causes drastic spectral changes at UV-visible wavelengths (Hapke, 2001), while the longer wavelength spectrum remains largely unaffected. Other laboratory results (e.g., Hiroi and Pieters, 1998) indicate that the UV-visible wavelength range is affected by simulated weathering processes in a manner similar to what is seen on Vesta. It is likely that Vesta has experienced relatively minor amounts of space weathering, as indicated by the spectral reversal, along with the subtle visible-near infrared weathering effects (e.g., Binzel et al., 1997).     

UV spectrum of Enceladus

We present a far ultraviolet (FUV) spectrum of Saturn’s moon Enceladus from the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST). We have put upper limits on emission from C, N, and O lines in Enceladus’ atmosphere and column densities for the C lines assuming solar resonance scattering. We find these upper limits to be relatively low—on the order of tens to thousands of Rayleighs and with C column densities on the order of 10⁸–10¹⁵ cm^?2, depending on the assumed source size. We also present a segment of a reflectance spectrum in the FUV from ～1900–2130 Å. This region was sensitive to the different ice mixtures in the model spectra reported by Hendrix et al. (Hendrix, A.R., Hansen, C.J., Holsclaw, G.M. [2010]. Icarus, 206, 608). We find the spectrum brightens quickly longward of ～1900 Å, constraining the absorption band observed by Hendrix et al. from ～170 to 190 nm. We find our data is consistent with the suggestion of Hendrix et al. of the presence of ammonia ice (or ammonia hydrate) to darken that region, and also possibly tholins to darken the mid-UV, as reported by Verbiscer et al. (Verbiscer, A.J., French, R.G., McGhee, C.A. [2005]. Icarus, 173, 66).     

An overview of Fiji's fisheries development

Development and societal changes in the twentieth century have transformed the nature of fishing in Fiji. This paper attempts to consolidate a large amount of decentralized work on the development of Fijian fisheries to address the long-term sustainability and economic viability of Fiji's marine resources. Taking a broad perspective, this paper provides an overview that connects the historic context of Fiji's fisheries development with economic policy to address overfishing. The analysis highlights the need for an overarching management approach that encompasses the integration of Fiji's offshore and inshore fisheries to ensure the achievement of long-term economic benefits.     

Toward Bayesian uncertainty quantification for forestry models used in the United Kingdom Greenhouse Gas Inventory for land use, land use change, and forestry

The Greenhouse Gas Inventory for the United Kingdom currently uses a simple carbon-flow model, CFLOW, to calculate the emissions and removals associated with forest planting since 1920. Here, we aim to determine whether a more complex process-based model, the BASic FORest (BASFOR) simulator, could be used instead of CFLOW. The use of a more complex approach allows spatial heterogeneity in soils and weather to be accounted for, but places extra demands on uncertainty quantification. We show how Bayesian methods can be used to address this problem.     

Spatial patterns and correlates of mortality due to selected non-communicable diseases among adults in South Africa, 2011

South Africa has a high prevalence of non-communicable diseases (NCDs) compared to other African countries. Government has predicted that NCDs will be a major threat of health in the country in the next 20–30 years and recommended a significant reduction in NCDs. This research studies spatial patterns of deaths resulting from chronic lower respiratory diseases (CLRD), malignant neoplasms of digestive organs (MNDO), diabetes mellitus (DM) and cerebrovascular diseases (CVD) among adults aged 15–69 years in 2011 at municipality level. The study uses secondary data from the civil registration system; population census; and supplementary information from the Business Register and a database of public health facilities. Moran’s Index, hot spot analysis and geographically weighted regression were applied to measure spatial autocorrelation of age-standardised death rates; to identify municipalities of high risk of deaths due to selected NCDs; and associated socio-economic and demographic factors. Clusters of high risk of deaths from selected NCDs were identified, with those for CLRD and MNDO mainly in the urban municipalities around the mid and western parts of the country while for DM and CVD they occurred mostly in the urban and rural north-eastern part, as well as in the urban municipalities of Northern Cape for CVD. Hot spots showed differential socio-economic and demographic risk factors in NCDs, which included sex, urbanisation, density of public hospitals; death occurrence in health facilities; smoking; asbestos roofing; mining and quarrying businesses. Findings highlight the importance of community-specific interventions and the need for a neighbourhood-based approach in tackling NCDs.     

Trophic structure of mesopelagic fishes in the Gulf of Mexico revealed by gut content and stable isotope analyses

Mesopelagic fishes represent an important component of the marine food web due to their global distributions, high abundances and ability to transport organic material throughout a large part of the water column. This study combined stable isotope (SIAs) and gut content analyses (GCAs) to characterize the trophic structure of mesopelagic fishes in the North‐Central Gulf of Mexico. Additionally, this study examined whether mesopelagic fishes utilized chemosynthetic energy from cold seeps. Specimens were collected (9–25 August 2007) over three deep (>1,000 m) cold seeps at discrete depths (surface to 1,503 m) over the diurnal cycle. GCA classified 31 species (five families) of mesopelagic fishes into five feeding guilds: piscivores, large crustacean consumers, copepod consumers, generalists and mixed zooplanktivores. However, these guilds were less clearly defined based on stable isotope mixing model (MixSIAR) results, suggesting diets may be more mixed over longer time periods (weeks–months) and across co‐occurring species. Copepods were likely important for the majority of mesopelagic fishes, consistent with GCA (this study) and previous literature. MixSIAR results also identified non‐crustacean prey items, including salps and pteropods, as potentially important prey items for mesopelagic fishes, including those fishes not analysed in GCA (Sternoptyx spp. and Melamphaidae). Salps and other soft‐bodied species are often missed in GCAs. Mesopelagic fishes had δ¹³C results consistent with particulate organic matter serving as the baseline organic carbon source, fueling up to three trophic levels. Fishes that undergo diel vertical migration were depleted in ¹⁵N relative to weak migrators, consistent with depth‐specific isotope trends in sources and consumers, and assimilation of ¹⁵N‐depleted organic matter in surface waters. Linear correlations between fish size and δ¹⁵N values suggested ontogenetic changes in fish diets for several species. While there was no direct measure of mesopelagic fishes assimilating chemosynthetic material, detection of infrequent consumption of this food resource may be hindered by the assimilation of isotopically enriched photosynthetic organic matter. By utilizing multiple dietary metrics (e.g. GCA, δ¹³C, δ¹⁵N, MixSIAR), this study better defined the trophic structure of mesopelagic fishes and allowed for insights on feeding, ultimately providing useful baseline information from which to track mesopelagic trophodynamics over time and space.     

Host‐dependent differences in resource use associated with Anilocra spp. parasitism in two coral reef fishes,as revealed by stable carbon and nitrogen isotope analyses

The role of parasites in trophic ecology is poorly understood in marine ecosystems. Stable isotope analyses (SIA) have been widely used in studies of trophic ecology, but have rarely been applied to study the role of parasites. Considering that some parasites are associated with altered host foraging patterns, SIA can help elucidate whether parasitism influences host trophic interactions. French grunt (Haemulon flavolineatum), an abundant Caribbean coral reef fish, contributes greatly to trophic connectivity. They typically depart the reef at dusk, feed overnight in seagrass beds, and return to the reef at dawn. The large parasitic isopod Anilocra haemuli commonly infects French grunt, and infected fish are less likely to complete their diel migration, and are in poorer condition than uninfected conspecifics. Brown chromis (Chromis multilineata) are diurnally feeding planktivores and infection by Anilocra chromis does not influence host condition. To determine if Anilocra infection influences host diet and foraging locality, we conducted stable carbon and nitrogen isotope analyses on scale, muscle, heart and gill tissues of infected and uninfected French grunt and brown chromis. We determined that all French grunt had δ¹³C values representative of seagrass habitats, but infected French grunt were significantly enriched in ¹³C and ¹⁵N compared to uninfected conspecifics. This suggests that compared to uninfected conspecifics, infected French grunt forage in seagrass, but on isotopically enriched prey, and/or are in poorer condition, which can elevate δ¹³C and δ¹⁵N values. For brown chromis, infection did not significantly influence any δ¹³C and δ¹⁵N values; hence they all foraged in the same environment and on similar prey. This is the first study to use SIA to examine differences in resource use by Caribbean coral reef fishes associated with parasitism and to evaluate how closely related parasites might have host‐dependent effects on host trophic ecology.