Modeling population effects of the Deepwater Horizon oil spill on a long-lived species

This research was enabled partly by a grant from The Gulf of Mexico Research Initiative (GOMRI).The 2010 Deepwater Horizon (DWH) oil spill exposed common bottlenose dolphins (Tursiops truncatus) in Barataria Bay, Louisiana to heavy oiling that caused increased mortality and chronic disease and impaired reproduction in surviving dolphins. We conducted photographic surveys and veterinary assessments in the decade following the spill. We assigned a prognostic score (good, fair, guarded, poor, or grave) for each dolphin to provide a single integrated indicator of overall health, and we examined temporal trends in prognostic scores. We used expert elicitation to quantify the implications of trends for the proportion of the dolphins that would recover within their lifetime. We integrated expert elicitation, along with other new information, in a population dynamics model to predict the effects of observed health trends on demography. We compared the resulting population trajectory with that predicted under baseline (no spill) conditions. Disease conditions persisted and have recently worsened in dolphins that were presumably exposed to DWH oil: 78% of those assessed in 2018 had a guarded, poor, or grave prognosis. Dolphins born after the spill were in better health. We estimated that the population declined by 45% (95% CI 14–74) relative to baseline and will take 35 years (95% CI 18–67) to recover to 95% of baseline numbers. The sum of annual differences between baseline and injured population sizes (i.e., the lost cetacean years) was 30,993 (95% CI 6607–94,148). The population is currently at a minimum point in its recovery trajectory and is vulnerable to emerging threats, including planned ecosystem restoration efforts that are likely to be detrimental to the dolphins’ survival. Our modeling framework demonstrates an approach for integrating different sources and types of data, highlights the utility of expert elicitation for indeterminable input parameters, and emphasizes the importance of considering and monitoring long-term health of long-lived species subject to environmental disasters. Article impact statement: Oil spills can have long-term consequences for the health of long-lived species; thus, effective restoration and monitoring are needed.Publisher PDFPeer reviewe

Reflections on the Formation and Growth of the SURE Network: a National Disciplinary Network to Enhance Undergraduate Research in the Sciences

The Science Undergraduate Research Experience (SURE) Network is an academic network comprised of nine Higher Education Institutions (HEI) in Ireland that seeks to enhance the profile of, and practices in, undergraduate research in the Sciences within the Technological Higher Education Sector. This paper presents the reflections of the network\u27s leaders on the formation and growth of the network over the period from 2015, just prior to its establishment, to 2020 when the network hosted its seventh undergraduate research conference, published its second undergraduate journal issue, and initiated a coordinated community of practice in response to the Covid-19 crisis. The paper presents the motivations of the leaders for establishing and joining the SURE network, their interpretation of how involvement in the network enhances practice in their own HEI, their reflections on how their own personal development was enhanced, their interpretation of the factors that have contributed to the success of the network, and the direction in which they see the network going in the future. The collective reflections of the leaders of the SURE Network, as presented in this paper, provide importance guidance for those seeking to establish similar academic networks, both in the area of undergraduate research and elsewhere

The design of biofunctional cinchona alkaloid derived catalysts : a new departure

THESIS 10284This thesis reports the synthesis of a novel class of quinine derived catalyst and its application to the field of organocatalysis. Initially, a suite of seven novel C-9 phenol and naphthol substituted quinine derivatives were synthesised. The activity of this suite of catalysts has been explored in a range of reactions. The nature of these catalysts allowed for unprecedented tuneability, indeed it was possible to discriminate between 1,2 and 1,4 addition reactions based on iterative changes to the catalyst structure, which allowed alteration to the distances between hydrogen bond donors and acceptors within the catalyst. It was also possible to identify the conformation of the catalyst as a key component in determining their selectivity. Analysis of the solution phase conformations for several of the catalysts is shown. Efforts towards making C-9 aniline-substituted derivatives have also been attempted; however this was not successful, despite the investigation of a variety of synthetic pathways. The application of the catalysts which proved to be active in 1,2-addition reactions to the dynamic kinetic resolution of azlactones was undertaken. It was possible, based on the choice of C-9 substituent, to select for either product enantiomer without changing the stereochemistry within the catalyst. By optimisation of the azlactone substrate it was possible to increase both the reactivity and selectivity observed. The most suitable of these catalysts was shown to promote the room temperature DKR of azlactones, affording the products derived from hindered ?-amino acids in up to 95% ee. Unfortunately for less hindered substrates enantioselectivity observed was uniformly more modest. Further investigation of modifications to the catalyst structure aimed at improving the overall efficiency of this catalytic system has been made, with large improvements in activity and selectivity achieved. The generation of a library of novel catalysts with significantly enhanced activity profiles compared to earlier catalysts of the same class has been described. Key considerations in the synthesis of quinine derivatives modified at several positions have been considered, with the scope of C-9 arylation reactions explored in depth. Furthermore it has been possible, through systematic modification of the catalyst to identify features in the catalyst structure which are key to both the activity and selectivity profile of these systems. The systematic modification of the catalyst structure has been used to optimise catalyst performance in the DKR of azlactones. This has allowed for the DKR of 2,4,6-trichlorobenzene substituted azlactones with enantioselectivity in excess of 90% ee, even using azlactones derived from unhindered amino acids. In the case of hindered azlactones exceptional enantioselectivity could be achieved with ee of up to 97% possible. Interestingly it was also possible to examine the mode of action of the catalyst. It was possible to discount nucleophilic catalysis as a catalyst role despite circumstantial evidence initially favouring it as a possibility. Furthermore, it was possible to observe that the catalysts synthesised were active in more than one conformation, which could favour the promotion of the formation of different product enantiomers. The alteration of the relative populations of these conformations by changes in temperature was shown to be possible and it was even possible, in one case, to demonstrate a temperature dependent change in the sense of enantiocontrol

A Comparative Analysis of Conventional and Deep Eutectic Solvent (DES)-Mediated Strategies for the Extraction of Chitin from Marine Crustacean Shells

Chitin, the second most abundant biopolymer on earth, is utilised in a wide range of applications including wastewater treatment, drug delivery, wound healing, tissue engineering, and stem cell technology among others. This review compares the most prevalent strategies for the extraction of chitin from crustacean sources including chemical methods that involve the use of harsh solvents and emerging methods using deep eutectic solvents (DES). In recent years, a significant amount of research has been carried out to identify and develop environmentally friendly processes which might facilitate the replacement of problematic chemicals utilised in conventional chemical extraction strategies with DES. This article provides an overview of different experimental parameters used in the DES-mediated extraction of chitin while also comparing the purity and yields of associated extracts with conventional methods. As part of this review, we compare the relative proportions of chitin and extraneous materials in different marine crustaceans. We show the importance of the species of crustacean shell in relation to chitin purity and discuss the significance of varying process parameters associated with different extraction strategies. The review also describes some recent applications associated with chitin. Following on from this review, we suggest recommendations for further investigation into chitin extraction, especially for experimental research pertaining to the enhancement of the “environmentally friendly” nature of the process. It is hoped that this article will provide researchers with a platform to better understand the benefits and limitations of DES-mediated extractions thereby further promoting knowledge in this area

The Dynamic Kinetic Resolution of Azlactones with Thiol Nucleophiles Catalyzed by Arylated, Deoxygenated Cinchona Alkaloids

A significant improvement of the available organocatalytic methods (in terms of product substrate scope and product enantiomeric excess) for the generation of enantioenriched α-amino acid thioesters via the dynamic kinetic resolution of azlactones is reported. C-9 arylated cinchona alkaloid catalysts have been found to be considerably superior to other bifunctional alkaloid catalysts as the promoters of this asymmetric process