Urchin predation and marine park residency in the Eastern Rock Lobster (Sagmariasus verreauxi): an initial assessment of its potential to control urchin populations

It has been speculated that Sagmariasus verreauxi (Eastern Rock Lobster) is an important predator of the barrens-forming urchin species Centrostephanus rodgersii (Long-Spined Urchin) and Heliocidaris erythrogramma (Short-Spined Urchin). Both urchin species can cause extreme habitat modification when occurring at high densities and this is considered a problem within NSW marine parks. Elsewhere, lobster predation on urchin by similar species Jasus edwardsii (Southern Rock Lobster) is considered key in controlling urchin populations, but whether S. verreauxi has a similar trophic impact is unknown. In this study, I for the first time investigate the likely value of S. verreauxi as an urchin control agent. I use a holistic approach that investigates lobster diet and feeding behaviour by using dissections and feeding trials and investigate urchin predation rates inside and outside of No-Take Sanctuary Zones (SZ’s) using diver surveys and urchin tethering experiments. I also use external tagging and passive-receiver acoustic telemetry to observe whether large and small lobster use and remain resident within sanctuary zones. Additionally, I have collated 125 observations on lobster size (carapace length, mm) between all experimental locations to test whether larger S. verreauxi are associated with SZ’s. My dissections and Gut Contents Analysis (GCA) of 118 S. verreauxi freshly collected and donated frozen from areas within the Sydney, Shoalhaven, Illawarra and Central Coast regions of NSW imply that lobsters eat urchins less frequently than expected and did not support the prediction that large lobsters eat more urchins. I found urchin material in \u3c 20% of the 118 lobsters dissected and did not find urchin in 96 individuals. I found H. erythrogramma exclusively in small-sized lobsters and C. rodgersii in lobster of various sizes, though at a lower frequency. Using open water mesocosms I presented two urchins of one species to 14 S. verreauxi during nocturnal feeding trials. Six of 14 lobsters fed on urchin (≈ 40%) and eight lobsters did not for the 14-day duration. I found that five of 16 H. erythrogramma (≈ 30%) and two of 12 C. rodgersii (≈ 17%) were eaten in total, and only the largest lobster consumed two urchins. When I performed GCA on the two lobsters that had eaten C. rodgersii I found no urchin spines in their guts, while I found H. erythrogramma spines in the guts of lobsters that had eaten H. erythrogramma. This 6 indicates that the accuracy of GCA may vary with factors such as lobster size and urchin species. Using a dataset gained through all experiments where lobsters were measured (dissections, feeding trials, acoustic tagging of lobsters) I found that S. verreauxi occurs within both SZs and surrounding fished areas and appears significantly larger on average within SZ areas. I also found that individually tagged C. rodgersii and H. erythrogramma presented on benthic urchin tethers were consumed ≈ 2-3x faster within SZs than in fished areas. I tagged and released 12 S. verreauxi across a range of sizes (105mm – 150mm CL) in Jervis Bay Marine Park (JBMP) and Bendalong, tracking them over 6 months (July – January). The largest lobsters were found in SZ’s. My acoustic receiver data download in January 2020 confirmed residency periods of S. verreauxi at SZ sites of 10 – 44 days. I found three JBMP lobsters showed residency in SZ areas while one was resident in a fished zone. Surprisingly, all lobsters showed a lag-time of 5 - 31 days between tagged-release and the first receiver detection. Lobsters were detected at times ranging from 12 - 72 days after tagging, with gaps of over one day between some detections. I could not estimate minimum distances travelled after tagging, as each lobster was only detected on a single receiver. Three lobsters tagged in JBMP were not detected at all, and no individuals were detected entering or leaving JBMP. The results of this initial study confirm that S. verreauxi consumes barrens-forming urchin species and that JBMP SZ’s are beneficial to lobster populations, though more research is needed. I indicate through urchin tethering and acoustic telemetry experiments that SZ’s could be an effective tool in controlling potential future outbreaks of barrens forming urchin-species. However, my dissections and feeding trials indicate that the contributions of S. verreauxi alone to urchin control might be less than expected. Lobster did show an apparent preference for H. erythrogramma over C. rodgersii, though this result should be treated with caution as GCA detection rates appear to differ between species. Importantly, I have shown that the medium-term tagging of lobsters using external tags and passive receiver acoustic telemetry is possible, although seemingly not overly efficient, and that lobsters can remain in SZ’s for up to 44 days. More work is needed to confirm the trends I discuss here, and these results are intended as the basis for future research

Cryptococcal Meningitis in Viet Nam

Cryptococcal neoformans is the commonest cause of invasive fungal disease in the world, causing up to 1.5 million cases of meningitis each year, and 1 million deaths. The aims of this thesis were to understand the differences in cryptococcal meningitis in Viet Nam in relation to the HIV infection status of the host, focussing on disease clinical phenotype, prognostic factors and the molecular epidemiology of the infecting isolates. In addition, the thesis examines the antifungal susceptibilities of Vietnamese Cryptococcus spp, how these vary by species and time, and the clinical utility of their measurement. Patients drawn from two prospective cohorts (HIV infected and HIV uninfected) form the basis of the thesis. The HIV uninfected patients are predominantly immunocompetent. Clinical and investigational findings are compared in relation to the literature. HIV patients had shorter durations of history and more frequent headache, but there were few differences in clinical presentation. Previously published prognostic factors were reassessed; only 3 of 40 (altered consciousness, cerebrospinal fluid (CSF) white cell count, and CSF cryptococcal antigen titre) were independently associated with outcome. Mortality was significantly higher in HIV infected patients, but the shapes of the survival curves were similar for both groups, most deaths occurring in the first 4 weeks of treatment. Amplified Fragment Length Polymorphism analysis was used to define the relationships between HIV positive and negative strains - a clade of C. neoformans var grubii with increased propensity to cause disease in immunocompetent patients was identified. The Sensititre® YeastOne® system was used to determine MICs of 7 antifungal drugs. The susceptibility of C. neoformans has decreased significantly over a 13 year period. No relationship with the rate of clearance of yeast from CSF and antifungal MIC was found, but raised amphotericin B MIC after 48 hours incubation may be associated with early death and warrants further investigation

Cellular and Chemical Dynamics Within the Nucleus Accumbens During Reward-related Learning and Decision Making

The ability to form and maintain associations between environmental cues, actions, and rewarding stimuli is an elementary yet fundamental aspect of learned behavior. Moreover, in order for organisms to optimize behavioral allocation after learning has occurred, such associations must be able to guide decision making processes as animals weigh the benefits and costs of potential actions. Multiple lines of research have identified that reward-related learning and decision making are mediated by a distributed network of brain nuclei that includes the nucleus accumbens (NAc) and its innervation from dopamine neurons located in the midbrain. However, the precise neural processing that underlies this function is unclear. The first set of experiments detailed in this dissertation took advantage of technological advances to characterize patterns of NAc dopamine release in real time, during behavioral performance. The results of the first experiment demonstrate for the first time that rapid dopamine release in the NAc is dramatically altered during stimulus-reward learning. Before learning, reward delivery produced robust increases in NAc dopamine concentration. After learning, these increases had completely transferred to the predictive cue and were no longer present when rewards were delivered. Further experiments revealed that cue-evoked increases in NAc dopamine concentration did not signal reward prediction alone, but reflected the work required to obtain rewards. Together, these results suggest that NAc dopamine encodes both the benefits and costs of predicted rewards. A second set of experiments used electrophysiological techniques to measure neural activity within the nucleus accumbens during decision making tasks. These experiments show that when rats were choosing between rewards with different effort requirements, a subset of NAc neurons tracked the degree of effort predicted by cues, while other neurons exhibited prolonged activation or inhibition as animals overcame large effort requirements to obtain rewards. Finally, when rats were choosing between rewards that came at different temporal delays, many NAc neurons exhibited changes in activity that correlated with reward delay. Such activity represents a candidate mechanism for linking actions with outcomes, and may also provide insight into the role of the NAc in psychiatric disorders characterized by maladaptive goal-directed behavior and decision making processes

Nucleus accumbens neurons encode Pavlovian approach behaviors: evidence from an autoshaping paradigm

Environmental stimuli predictive of appetitive events can elicit Pavlovian approach responses that enhance an organism’s ability to track and secure natural rewards. We examined the activity of individual nucleus accumbens (NAc) neurons during the performance of approach behaviors. Animals were presented with conditioned stimuli that were either positive (the CS+) or negative (the CS-) predictors of reward. Approach responses directed at these cues were recorded as lever presses and were significantly more likely to occur during CS+ presentations. On the test day, 75% of NAc neurons exhibited changes in firing rate (termed 'phasically active') during CS+ presentations. Of these cells, 47% were characterized by time-locked increases in cell firing while 53% showed reductions in firing for the duration of the CS+. The same cells typically showed little or no change during CS- presentations. These results suggest that NAc neurons encode reward prediction and/or approach responses elicited by reward-paired cues

Changes in UK ophthalmology surgical training: analysis of cumulative surgical experience 2009-2015.

OBJECTIVE: To investigate changes in the patterns of cumulative surgical experience for ophthalmologists in the UK following the introduction of a new national training scheme. DESIGN: Retrospective review of all surgical training records submitted to the UK Royal College of Ophthalmologists by trainees for the award of Certificate of Completion of Training (CCT) for the period 2009-2015. SETTING: Secondary level care, UK. PARTICIPANTS: 539 trainees achieving CCT over the 7-year study period. INTERVENTIONS: Higher specialist training or ophthalmology specialist training. OUTCOME MEASURES: Number of CCT awards by years and procedures performed for cataract surgery, strabismus, corneal grafts, vitreoretinal (VR) procedures, oculoplastics and glaucoma. RESULTS: Cataract surgical experience showed little change with median number performed/performed supervised (P/PS) 592, IQR: 472-738; mean: 631. Similarly, the median number of strabismus (P/PS 34), corneal grafts (assisted, 9) and VR procedures (assisted, 34) appeared constant. There was a trend towards increasing surgical numbers for oculoplastics (median 116) and glaucoma (57). Overall case numbers for ophthalmic specialist training (OST) trainees (7-year training programme) were higher than higher surgical training (HST) trainees (4.5-year programme) with the exception of squint (P/PS), corneal grafts (P/PS) and VR cases (P/PS). CONCLUSIONS: Overall case numbers reported at time of CCT application appear stable or with a marginal trend towards increasing case numbers. HST (4.5-year programme) case numbers do not include those performed before entry to HST, and although case numbers tended to be higher for OST trainees (7-year programme) compared with HST trainees, they were not proportionately so

Advances in quantum machine learning

Here we discuss advances in the field of quantum machine learning. The following document offers a hybrid discussion; both reviewing the field as it is currently, and suggesting directions for further research. We include both algorithms and experimental implementations in the discussion. The field's outlook is generally positive, showing significant promise. However, we believe there are appreciable hurdles to overcome before one can claim that it is a primary application of quantum computation.Comment: 38 pages, 17 Figure

Development of behavioral preferences for the optimal choice following unexpected reward omission is mediated by a reduction of D 2‐like receptor tone in the nucleus accumbens

To survive in a dynamic environment, animals must identify changes in resource availability and rapidly apply adaptive strategies to obtain resources that promote survival. We have utilised a behavioral paradigm to assess differences in foraging strategy when resource (reward) availability unexpectedly changes. When reward magnitude was reduced by 50% (receive one reward pellet instead of two), male and female rats developed a preference for the optimal choice by the second session. However, when an expected reward was omitted (receive no reward pellets instead of one), subjects displayed a robust preference for the optimal choice during the very first session. Previous research shows that, when an expected reward is omitted, dopamine neurons phasically decrease their firing rate, which is hypothesised to decrease dopamine release preferentially affecting D 2‐like receptors. As robust changes in behavioral preference were specific to reward omission, we tested this hypothesis and the functional role of D 1‐ and D 2‐like receptors in the nucleus accumbens in mediating the rapid development of a behavioral preference for the rewarded option during reward omission in male rats. Blockade of both receptor types had no effect on this behavior; however, holding D 2‐like, but not D 1‐like, receptor tone via infusion of dopamine receptor agonists prevented the development of the preference for the rewarded option during reward omission. These results demonstrate that avoiding an outcome that has been tagged with aversive motivational properties is facilitated through decreased dopamine transmission and subsequent functional disruption of D 2‐like, but not D 1‐like, receptor tone in the nucleus accumbens. This study investigates the role of dopamine receptors in the nucleus accumbens in altering behavior in response to the omission of an expected reward. Similarly to controls, multiple doses of a D 1‐like receptor agonist, D 1‐like receptor antagonist, and D 2‐like receptor antagonist do not prevent subjects from developing a robust behavioral preference for the rewarded lever and avoiding the omitted‐reward lever during the first session of reward omission. However, the D 2‐like agonist quinpirole dose‐dependently blocks a behavioral preference for the rewarded lever, suggesting that reductions in D 2‐like receptor tone are necessary for altering behavior away from an aversive option and toward the optimal choice.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/99645/1/ejn12253.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/99645/2/ejn12253-sup-0001-Supplement.pd