Sandra M. Saunders

A Rapid Method for Determining Lipid Fraction Ratios of Hard Corals under Varying Sediment and Light Regimes

Environmental Context.Monitoring the health of coral reef systems is vitally important to maintain and manage these threatened, complex and biodiverse natural ecosystems. Although total lipid content has been suggested as a potential index of coral condition, current methods of measurement are time consuming, technically challenging and expensive. These limitations have prohibited the application of coral lipid content as an impact-monitoring tool. The development of a practical and rapid method to determine lipid fraction ratios has the potential to lead towards an effective tool for coral reef monitoring. Abstract.Lipid content has been used as a measure of energetic status and condition in a number of fish and invertebrate species and can potentially be applied to hard corals. However, common methods for measuring lipid content are time consuming, technically challenging and expensive and these limitations have prohibited the application of lipid content as an impact-monitoring tool. To overcome these limitations, a rapid low-tech method for determining neutral to polar lipid ratios from hard coral tissue samples has been developed. This paper describes the development of the method together with a preliminary application of the technique carried out in a field study to determine whether the relative amounts of non-polar storage lipid to polar structural lipid may provide insight into the nutritional condition of individual coral colonies under differing environmental stresses. Variation in the lipid ratios of the hard coral Acropora nobilis, collected from the Montebello Islands off Western Australia, was correlated with local light and sediment regimes. This initial application of the method has demonstrated the viability of the technique, which subsequently has the potential to be applied in the analysis of a large number of samples as would be required in environmental monitoring.

Tropospheric volatile organic compounds in China

Photochemical smog, characterized by high concentrations of ozone (O3) and fine particles (PM2.5) in the atmosphere, has become one of the top environmental concerns in China. Volatile organic compounds (VOCs), one of the key precursors of O3 and secondary organic aerosol (SOA) (an important component of PM2.5), have a critical influence on atmospheric chemistry and subsequently affect regional and global climate. Thus, VOCs have been extensively studied in many cities and regions in China, especially in the North China Plain, the Yangtze River Delta and the Pearl River Delta regions where photochemical smog pollution has become increasingly worse over recent decades. This paper reviews the main studies conducted in China on the characteristics and sources of VOCs, their relationship with O3 and SOA, and their removal technology. This paper also provides an integrated literature review on the formulation and implementation of effective control strategies of VOCs and photochemical smog, as well as suggestions for future directions of VOCs study in China.

Symbiodinium Genotypic and Environmental Controls on Lipids in Reef Building Corals

Background Lipids in reef building corals can be divided into two classes; non-polar storage lipids, e.g. wax esters and triglycerides, and polar structural lipids, e.g. phospholipids and cholesterol. Differences among algal endosymbiont types are known to have important influences on processes including growth and the photobiology of scleractinian corals yet very little is known about the role of symbiont types on lipid energy reserves. Methodology/Principal Findings The ratio of storage lipid and structural lipid fractions of Scott Reef corals were determined by thin layer chromatography. The lipid fraction ratio varied with depth and depended on symbiont type harboured by two corals (Seriatopora hystrix and Pachyseris speciosa). S. hystrix colonies associated with Symbiodinium C1 or C1/C# at deep depths (>23 m) had lower lipid fraction ratios (i.e. approximately equal parts of storage and structural lipids) than those with Symbiodinium D1 in shallow depths (<23 m), which had higher lipid fraction ratios (i.e. approximately double amounts of storage relative to structural lipid). Further, there was a non-linear relationship between the lipid fraction ratio and depth for S. hystrix with a modal peak at ∼23 m coinciding with the same depth as the shift from clade D to C types. In contrast, the proportional relationship between the lipid fraction ratio and depth for P. speciosa, which exhibited high specificity for Symbiodinium C3 like across the depth gradient, was indicative of greater amounts of storage lipids contained in the deep colonies. Conclusions/Significance This study has demonstrated that Symbiodinium exert significant controls over the quality of coral energy reserves over a large-scale depth gradient. We conclude that the competitive advantages and metabolic costs that arise from flexible associations with divergent symbiont types are offset by energetic trade-offs for the coral host.

Development and preliminary test results of an expert system for the automatic generation of tropospheric VOC degradation mechanisms

Abstract The methodology and protocol used for the construction of the master chemical mechanism (MCM) has been coupled with techniques from knowledge-based systems to develop an expert system, specifically tailored for the automatic generation of tropospheric volatile organic compound (VOC) degradation schemes. To solve the problem of automatic mechanism construction processes leading to unmanageably large mechanisms for species containing more than a few carbon atoms, strategies are developed to reduce mechanism growth. To test the mechanisms generated by the expert system, some preliminary exemplar schemes have been embedded in a simple box model to provide a comparison with the complete degradation schemes available from the MCM web site. Profiles were obtained for several of the stable and radical species. Those of the parent VOC, O 3 , OH, HO 2 and CH 3 O 2 are in good agreement with profiles generated using the reference MCM schemes. Other profiles exhibited a much larger disparity, notably the sum of the peroxy radicals (RO 2 ). These disparities provide insights for refinement of the expert system rule base.

MECHANISM REDUCTION FOR TROPOSPHERIC CHEMISTRY : BUTANE OXIDATION

A detailed butane oxidation mechanism for the troposphere was reduced using objective methods. The reductions of this large scheme have been based on sensitivity analysis over a wide range of atmospheric conditions, characterised by extremely low, intermediate and high [NO x ]. The quasi-steady-state approximation (QSSA) was applied to reduce further the number of differential (rate) equations needed to describe the kinetics. Significant simplifications were achieved leading to reductions in the number of differential equations of a factor of 6–10, depending on the conditions. The reductions lead to a greater transparency in the mechanism and to a more facile identification of key reaction routes. This facility is demonstrated via a discussion of secondary routes to HO 2 via carbonyl photolysis.

Comments on Recent Work by Zhang and Colleagues: “Uropygial Gland-Secreted Alkanols Contribute to Olfactory Sex Signals in Budgerigars”

Comments on Recent Work by Zhang and Colleagues: ‘‘Uropygial GlandSecreted Alkanols Contribute to Olfactory Sex Signals in Budgerigars’’ Jérôme Mardon, Sandra M. Saunders and Francesco Bonadonna Behavioural Ecology Group, Department of Population Biology, Centre d’Ecologie Fonctionnelle et Evolutive, Centre National de la Recherche Scientifique (CEFE-CNRS UMR 5175), 1919 route de Mende, 34293 Montpellier, France and Atmospheric and Environmental Chemistry Research (AECR) Group, School of Biomedical, Biomolecular and Chemical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia

Examination of regional ozone formation

Airshed modeling to determine photochemical ozone creation potentials (POCPs) provides a means of ranking regional emission contributions of individual volatile organic compounds (VOC) to O3 formation. Here POCPs are determined for Perth, Western Australia and compared with those from other Continents; Europe (UK), America (USA) and Asia (The Pearl River Delta and Hong Kong). Considering only the commonality of VOC across the top 50 ranked VOC by POCP and top 15 ranked VOC by POCP-weighted emission, indicates a group of 27 alkane, alkene, aromatic and oxygenated VOC that should be considered as useful targets in emission limitation and reduction strategies. This target group includes; ethene, propene, the butenes (6 VOC) and pentenes (3 VOC), trimethyl benzenes (2 VOC), xylenes (3 VOC), toluene, ethyl benzene, m-ethyl toluene, butanes (2 VOC), pentanes (2 VOC) and 2-methyl heptane, as well as methanal, ethanal and methyl-i-butyl ketone. The top 50 ranked VOC by POCP (from >130 VOC) also highlights those more reactive VOC that should be taken note of, as potential high ozone contributors, should emissions increase. POCPs are determined for Perth, Western Australia & compared with those from other Continents.VOC are ranked by POCP & POCP-weighted emission across high and low air pollution regions.Some common VOC contributing to high O3 are identified across 4 Continents.These common VOC are a group of 27 alkane, alkene, aromatic and oxygenated compounds.Overall analysis identifies potential target VOC for further emission control studies.

Modeling C1–C4 Alkyl Nitrate Photochemistry and Their Impacts on O3 Production in Urban and Suburban Environments of Hong Kong

Author(s): Lyu, XP; Guo, H; Wang, N; Simpson, IJ; Cheng, HR; Zeng, LW; Saunders, SM; Lam, SHM; Meinardi, S; Blake, DR | Abstract: ©2017. American Geophysical Union. All Rights Reserved. As intermediate products of photochemical reactions, alkyl nitrates (RONO2) regulate ozone (O3) formation. In this study, a photochemical box model incorporating master chemical mechanism well reproduced the observed RONO2 at an urban and a mountainous site, with index of agreement in the range of 0.66–0.73. The value 0.0003 was identified to be the most appropriate branching ratio for C1 RONO2, with the error less than 50%. Although levels of the parent hydrocarbons and nitric oxide (NO) were significantly higher at the urban site than the mountainous site, the production of C2–C3 RONO2 was comparable to or even lower than at the mountainous site, due to the lower concentrations of oxidative radicals in the urban environment. Based on the profiles of air pollutants at the mountainous site, the formation of C2–C4 RONO2 was limited by NOx (volatile organic compounds (VOCs)) when total volatile organic compounds (TVOCs)/NOx was higher (lower) than 10.0 ± 0.4 parts per billion by volume (ppbv)/ppbv. This dividing ratio decreased (p l 0.05) to 8.7 ± 0.4 ppbv/ppbv at the urban site, mainly due to the different air pollutant profiles at the two sites. For the formation of C1 RONO2, the NOx-limited regime extended the ratio of TVOCs/NOx to as low as 2.4 ± 0.2 and 3.1 ± 0.1 ppbv/ppbv at the mountainous and urban site, respectively. RONO2 formation led to a decrease of simulated O3, with reduction efficiencies (O3 reduction/RONO2 production) of 4–5 parts per trillion by volume (pptv)/pptv at the mountainous site and 3–4 pptv/pptv at the urban site. On the other hand, the variations of simulated O3 induced by RONO2 degradation depended upon the regimes controlling O3 formation and the relative abundances of TVOCs and NOx.

Guidelines for Collecting and Extracting Avian Odors in a Remote Field: Case Study of a Subantarctic Seabird

Recent research on avian chemical signaling has highlighted the need for new appropriate protocols especially for sampling, and analyzing, compounds borne by individuals Although many studies have already examined the chemical substances secreted by birds, only few works have done so from the perspective of chemical communication and none have focused on the actual airborne compounds which make up the final odor. As well as the relative infancy of the field, this gap originates from the absence of an appropriate methodological framework. In this study, we provide a methodological guideline of various combinations of sampling and extraction techniques that have been developed and tested in our research. These include: analysis of (1) uropygial secretion samples by solvent extraction, (2) feather lipids by solvent extraction, (3) feather lipids by direct solid-phase thermal desorption, (4) cotton swab (rubbed on bird) by solid-phase microextraction (SPME), (5) cotton swab by direct solid-phase thermal desorption and (6) airborne volatiles by thermal desorption. To achieve this, we used the particular case study of blue petrels (Halobaena caerulea), a Subantarctic procellariiform seabird, living on remote islands and known for its good olfactory capabilities. Outcomes from the different methods are presented in terms of chromatographic quality, the number and properties of the analytes resolved, and their suitability for the work in isolated locations. Advantages and limitations of each method are discussed together with challenges that remain to make the new protocols presented more robust for field chemo-ecologists.