Life history of a native emydid turtle (Malaclemys terrapin centrata) on the remote oceanic islands of Bermuda

Diamondback terrapins (Malaclemys terrapin) are native to the remote oceanic islands of Bermuda and presently inhabit only four small brackish water ponds on a private golf course. The life history of this species is poorly understood on Bermuda and so the aim of this study was to fill these knowledge gaps, to compare the results with what is known from other areas in the North American range, and to inform the development of a local management plan. The results of a mark-recapture census revealed that ca. 100 individuals ≥81 mm straight carapace length live on Bermuda, of which nearly half (48.5%) were considered sexually mature. The population is dominated by females (sex ratio 2.9:1) and annual recruitment over the three year period was found to be extremely low (approximately two terrapins). Female diamondback terrapins in Bermuda nest almost exclusively within a limited number of sand bunkers on the golf course. Nesting commenced in late March or early April and ended in late August. Peak oviposition was observed in May and June. Clutch size averaged 5.1 eggs (range 0-10; SD 2.4) and the incubation period averaged 61.8 days (range 49-83; SD 10.5). Delayed emergence was documented, with 43.8% of the hatchlings remaining in their natal nests over the winter months. The mean annual hatching success rate was determined to be 19% (range 17.6-21; SD 1.9). Radio-telemetry was used to investigate the movements and survivorship of postemergent hatchling diamondback terrapins. The results indicated that mangrove swamps and grass-dominated marshes adjacent to the ponds are important developmental habitats for hatchlings. Yellow-crowned night herons (Nyctanassa violacea) were found to be significant predators of small terrapins during spring emergence. Small aquatic gastropods comprised 66.7% of the faecal samples analysed from the Bermudian population. Scavenged fish and vertebrate animal remains, terrestrial arthropods, polychaete worms and bivalves were consumed in lesser amounts. Sediment from the pond environment was found in 74% of the faecal samples analysed and is believed to have been incidentally ingested while foraging for the small benthic gastropods. Eco-toxicological analyses of the pond sediment, prey and terrapin eggs showed that the Bermudian diamondback terrapins live and feed in wetland habitats characterised by chronic, multifactorial contamination; principally total petroleum hydrocarbons, polycyclic aromatic hydrocarbons and a variety of heavy metals. This study found that some of those contaminants are accumulating in the gastropod prey as well as being transferred to terrapin eggs. This may be reducing the incidence of successful embryonic development for this species in Bermuda and may likely contribute to the observed low hatching rates. These collective findings indicate that the Bermudian population is very vulnerable to local extirpation.

Cocrystallisation involving the thioamide, amide and imide functional groups

The work presented in this dissertation focused on the development and characterisation of novel cocrystals that incorporated the thioamide, amide and imide functional groups. A particular emphasis was placed on the characterisation of these cocrystals by single crystal X-ray diffraction methods. In Chapter One a summary of the intermolecular interactions utilised in this work and a short review of the solid state and multicomponent systems is provided. A brief introduction to the ways in which different multicomponent systems can be distinguished, crystal engineering strategies and a number of cocrystal applications highlights the importance the understanding of intermolecular interactions can have on the physical and chemical properties of crystalline materials. Chapter Two is the first Results and Discussion chapter and includes an introduction that is specific to the chapter. The main body of this work focuses on the primary aromatic thioamide functional group and its propensity to cocrystallise with a number of sulfoxides. Unlike the amide functional group, thioamides are not commonly employed in cocrystallisation studies. This chapter presents the first direct comparison between the cocrystallisation abilities of these two functional groups and the intermolecular hydrogen bonding interactions present in the cocrystal structures are examined. Chapter Three describes the crystal landscape of a short series of secondary aromatic amides and their analogous thioamides. Building on the results obtained in Chapter Two, a cocrystal screen of the secondary thioamides with the sulfoxide functional group was carried out in order to determine the effect removing a hydrogen bond had on the supramolecular synthons observed in the cocrystals. These secondary thioamides are also utilised in Chapter Four, which examines their halogen bonding capabilities with two organoiodine coformers: 1,2- and 1,4-diiodotetrafluorobenzene. Chapter Five explores the cocrystallisation abilities of three related cyclic imides as coformers for cocrystallisation with a range of commonly used coformers. Chapter Six is an overall conclusions chapter that highlights the findings of the results presented in Chapters Two to Five. Chapter Seven details the instrument and experimental data for the compounds and cocrystals discussed in the Results and Discussion Chapters. The accompanying CD contains all of the crystallographic data in .cif format for the novel single crystal structures characterised in this work.