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result(s) for
"Gordon, Timothy A. C."
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Coral Reef Monitoring, Reef Assessment Technologies, and Ecosystem-Based Management
by
Gordon, Timothy A. C.
,
Gudka, Mishal
,
Chou, Loke Ming
in
Acidification
,
Algae
,
Anthropogenic factors
2019
Coral reefs are exceptionally biodiverse, and human dependence on their ecosystem services is high. Reefs experience significant direct and indirect anthropogenic pressures, and provide a sensitive indicator of coastal ocean health, climate change and ocean acidification, with associated implications for society. Monitoring coral reef status and trends is essential to better inform science, management and policy, but the projected collapse of reef systems within a few decades makes the provision of accurate and actionable monitoring data urgent. The Global Coral Reef Monitoring Network has been the foundation for global reporting on coral reefs for two decades, and is entering into a new phase with improved operational and data standards incorporating the Essential Ocean Variables (EOVs) (www.goosocean.org/eov) and Framework for Ocean Observing developed by the Global Ocean Observing System. Three EOVs provide a robust description of reef health: hard coral cover and composition, macro-algal canopy cover, and fish diversity and abundance. A data quality model based on comprehensive metadata is designed to facilitate maximum global coverage of coral reef data, and tangible steps to track capacity building. Improved monitoring of events such as mass bleaching and disease outbreaks, citizen science and socio-economic monitoring have the potential to greatly improve the relevance of monitoring to managers and stakeholders, and to address the complex and multi- dimensional interactions between reefs and people. XX THERE IS SOMETHING WRONG IN THE ABSTRACT WORD LIMIT, ONE MORE PARAGRAPH WAS INCLUDED IN THE ORIGINAL TEXT!!
Journal Article
Acoustic enrichment can enhance fish community development on degraded coral reef habitat
by
Gordon, Timothy A. C.
,
Nedelec, Sophie L.
,
Barnes, Kasey
in
631/158/2450
,
631/158/672
,
631/158/854
2019
Coral reefs worldwide are increasingly damaged by anthropogenic stressors, necessitating novel approaches for their management. Maintaining healthy fish communities counteracts reef degradation, but degraded reefs smell and sound less attractive to settlement-stage fishes than their healthy states. Here, using a six-week field experiment, we demonstrate that playback of healthy reef sound can increase fish settlement and retention to degraded habitat. We compare fish community development on acoustically enriched coral-rubble patch reefs with acoustically unmanipulated controls. Acoustic enrichment enhances fish community development across all major trophic guilds, with a doubling in overall abundance and 50% greater species richness. If combined with active habitat restoration and effective conservation measures, rebuilding fish communities in this manner might accelerate ecosystem recovery at multiple spatial and temporal scales. Acoustic enrichment shows promise as a novel tool for the active management of degraded coral reefs.
Healthy coral reefs have an acoustic signature known to be attractive to coral and fish larvae during settlement. Here the authors use playback experiments in the field to show that healthy reef sounds can increase recruitment of juvenile fishes to degraded coral reef habitat, suggesting that acoustic playback could be used as a reef management strategy.
Journal Article
Habitat degradation negatively affects auditory settlement behavior of coral reef fishes
by
Gordon, Timothy A. C.
,
McCormick, Mark I.
,
Meekan, Mark G.
in
Attraction
,
Biological Sciences
,
Bleaching
2018
Coral reefs are increasingly degraded by climate-induced bleaching and storm damage. Reef recovery relies on recruitment of young fishes for the replenishment of functionally important taxa. Acoustic cues guide the orientation, habitat selection, and settlement of many fishes, but these processes may be impaired if degradation alters reef soundscapes. Here, we report spatiotemporally matched evidence of soundscapes altered by degradation from recordings taken before and after recent severe damage on Australia’s Great Barrier Reef. Postdegradation soundscapes were an average of 15 dB re 1 μPa quieter and had significantly reduced acoustic complexity, richness, and rates of invertebrate snaps compared with their predegradation equivalents. We then used these matched recordings in complementary light-trap and patch-reef experiments to assess responses of wild fish larvae under natural conditions. We show that postdegradation soundscapes were 8% less attractive to presettlement larvae and resulted in 40%less settlement of juvenile fishes than predegradation soundscapes; postdegradation soundscapes were no more attractive than open-ocean sound. However, our experimental design does not allow an estimate of how much attraction and settlement to isolated postdegradation soundscapes might change compared with isolated predegradation soundscapes. Reductions in attraction and settlement were qualitatively similar across and within all trophic guilds and taxonomic groups analyzed. These patterns may lead to declines in fish populations, exacerbating degradation. Acoustic changes might therefore trigger a feedback loop that could impair reef resilience. To understand fully the recovery potential of coral reefs, we must learn to listen.
Journal Article
A simple model predicts how warming simplifies wild food webs
by
Pichler, Doris E
,
Woodward, Guy
,
Gallo, Bruno
in
Allometry
,
Aquatic ecosystems
,
Computer simulation
2019
Warming increases the metabolic demand of consumers1, strengthening their feeding interactions2. This could alter energy fluxes3–5 and even amplify extinction rates within the food web6–8. Such effects could simplify the structure and dynamics of ecological networks9,10, although an empirical test in natural systems has been lacking. Here, we tested this hypothesis by characterizing around 50,000 directly observed feeding interactions across 14 naturally heated stream ecosystems11–15. We found that higher temperature simplified food-web structure and shortened the pathways of energy flux between consumers and resources. A simple allometric diet breadth model10,16 predicted 68–82% of feeding interactions and the effects of warming on key food-web properties. We used model simulations to identify the underlying mechanism as a change in the relative diversity and abundance of consumers and their resources. This model shows how warming can reduce the stability of aquatic ecosystems by eroding the structural integrity of the food web. Given these fundamental drivers, such responses are expected to be manifested more broadly and could be predicted using our modelling framework and knowledge of how warming alters some routinely measured characteristics of organisms.
Journal Article
Changes in feeding selectivity of freshwater invertebrates across a natural thermal gradient
by
Furey, Paula C
,
Gordon, Timothy A C
,
O’Gorman, Eoin J
in
Bacillariophyta
,
Biofilms
,
Consumers
2018
Abstract
Environmental warming places physiological constraints on organisms, which may be mitigated by their feeding behavior. Theory predicts that consumers should increase their feeding selectivity for more energetically valuable resources in warmer environments to offset the disproportionate increase in metabolic demand relative to ingestion rate. This may also result in a change in feeding strategy or a shift towards a more specialist diet. This study used a natural warming experiment to investigate temperature effects on the feeding selectivity of three freshwater invertebrate grazers: the snail Radix balthica, the blackfly larva Simulium aureum, and the midgefly larva Eukiefferiella minor. Chesson’s Selectivity Index was used to compare the proportional abundance of diatom species in the guts of each invertebrate species with corresponding rock biofilms sampled from streams of different temperature. The snails became more selective in warmer streams, choosing high profile epilithic diatoms over other guilds and feeding on a lower diversity of diatom species. The blackfly larvae appeared to switch from active collector gathering of sessile high profile diatoms to more passive filter feeding of motile diatoms in warmer streams. No changes in selectivity were observed for the midgefly larvae, whose diet was representative of resource availability in the environment. These results suggest that key primary consumers in freshwater streams, which constitute a major portion of invertebrate biomass, can change their feeding behavior in warmer waters in a range of different ways. These patterns could potentially lead to fundamental changes in the flow of energy through freshwater food webs.
Journal Article
Redefining critical illness
by
Buchman, Timothy G.
,
Angus, Derek C.
,
Maslove, David M.
in
692/308/575
,
692/700/139/1420
,
692/700/565
2022
Research and practice in critical care medicine have long been defined by syndromes, which, despite being clinically recognizable entities, are, in fact, loose amalgams of heterogeneous states that may respond differently to therapy. Mounting translational evidence—supported by research on respiratory failure due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection—suggests that the current syndrome-based framework of critical illness should be reconsidered. Here we discuss recent findings from basic science and clinical research in critical care and explore how these might inform a new conceptual model of critical illness. De-emphasizing syndromes, we focus on the underlying biological changes that underpin critical illness states and that may be amenable to treatment. We hypothesize that such an approach will accelerate critical care research, leading to a richer understanding of the pathobiology of critical illness and of the key determinants of patient outcomes. This, in turn, will support the design of more effective clinical trials and inform a more precise and more effective practice at the bedside.
The authors propose a new conceptual model of critical illness that moves away from the current syndrome-based framework in favor of more precise biological descriptors—spurred by mounting translational evidence and insights from Coronavirus Disease 2019 (COVID-19) research.
Journal Article
Cediranib in patients with relapsed platinum-sensitive ovarian cancer (ICON6): a randomised, double-blind, placebo-controlled phase 3 trial
by
Ledermann, Jonathan A
,
Farrelly, Laura
,
Rustin, Gordon J S
in
Aged
,
Angiogenesis
,
Antineoplastic Combined Chemotherapy Protocols - therapeutic use
2016
Angiogenesis is a validated clinical target in advanced epithelial ovarian cancer. Cediranib is an oral antiangiogenic vascular endothelial growth factor receptor 1–3 inhibitor that has shown antitumour activity in recurrent ovarian cancer. We assessed efficacy and safety of cediranib in combination with platinum-based chemotherapy and as continued maintenance treatment in patients with first relapse of platinum-sensitive ovarian cancer.
In this randomised, three-arm, double-blind, placebo-controlled phase 3 trial, we randomly assigned patients aged 18 years or older with relapsed platinum-sensitive ovarian cancer at 63 centres in Australia, Canada, New Zealand, Spain, and the UK. Participants received up to six cycles of platinum-based chemotherapy (once every 3 weeks) then entered a maintenance phase. Participants were randomly allocated (2:3:3), with five stratification factors and in alternating blocks, to receive placebo alongside chemotherapy and then placebo only maintenance (arm A; reference), cediranib 20 mg once-daily alongside chemotherapy then placebo only maintenance (arm B; concurrent), or cediranib 20 mg once-daily alongside chemotherapy then cediranib 20 mg once-daily maintenance (arm C; maintenance). Patients continued treatment to progression or excessive toxic effects. The primary efficacy endpoint was progression-free survival between arms A and C. Efficacy analysis was by intention to treat. Safety was assessed in all patients who received the allocated study drug. This trial is registered with ClinicalTrials.gov, number NCT00532194; the ISRCTN registry, number ISRCTN68510403; and ANZ Clinical Trials Registry, number ACTRN1261000016003.
We randomly assigned 486 women between Nov 13, 2007, and Dec 23, 2011; results presented are for 456 patients randomly assigned subsequent to the 30mg safety phase. During a median of 19·5 months (IQR 14–26) follow-up, 113 (96%) of 118 women assigned to arm A and 141 (86%) of 164 assigned to arm C had disease progression. Median progression-free survival was 11·0 months (95% CI 10·4–11·7) in arm C and 8·7 months (7·7–9·4) in arm A (hazard ratio 0·56, 0·44–0·72, p<0·0001). 156 (90%) of 174 patients in arm B had disease progression, and median progression-free survival was 9·9 months (95% CI 9·4–10·5). Diarrhoea, neutropenia, hypertension, and voice changes were significantly more common, during chemotherapy with cediranib, and diarrhoea, hypothyroidism and voice changes were more common during maintenance. Poor compliance with cediranib was noted during maintenance treatment with toxic effects being the most common cause for discontinuation.
Cediranib, when given orally with chemotherapy and continued as maintenance, yielded a meaningful improvement in progression-free survival in women with recurrent platinum-sensitive ovarian cancer, albeit with added toxic effects. The positive results in ICON6 could provide women with a new therapeutic option for recurrent ovarian cancer. Assessment of the secondary endpoint of overall survival will need longer follow-up.
Medical Research Council, Cancer Research UK, Canadian Cancer Society Research Institute, Cancer Australia, National Gynecological Cancer Centre, and AstraZeneca.
Journal Article
Standard chemotherapy with or without bevacizumab for women with newly diagnosed ovarian cancer (ICON7): overall survival results of a phase 3 randomised trial
by
Cervantes, Andrés
,
Rustin, Gordon
,
Kaplan, Richard
in
Antibodies, Monoclonal, Humanized - administration & dosage
,
Antineoplastic Combined Chemotherapy Protocols - adverse effects
,
Antineoplastic Combined Chemotherapy Protocols - therapeutic use
2015
The ICON7 trial previously reported improved progression-free survival in women with ovarian cancer with the addition of bevacizumab to standard chemotherapy, with the greatest effect in patients at high risk of disease progression. We report the final overall survival results of the trial.
ICON7 was an international, phase 3, open-label, randomised trial undertaken at 263 centres in 11 countries across Europe, Canada, Australia and New Zealand. Eligible adult women with newly diagnosed ovarian cancer that was either high-risk early-stage disease (International Federation of Gynecology and Obstetrics [FIGO] stage I–IIa, grade 3 or clear cell histology) or more advanced disease (FIGO stage IIb–IV), with an Eastern Cooperative Oncology Group performance status of 0–2, were enrolled and randomly assigned in a 1:1 ratio to standard chemotherapy (six 3-weekly cycles of intravenous carboplatin [AUC 5 or 6] and paclitaxel 175 mg/m2 of body surface area) or the same chemotherapy regimen plus bevacizumab 7·5 mg per kg bodyweight intravenously every 3 weeks, given concurrently and continued with up to 12 further 3-weekly cycles of maintenance therapy. Randomisation was done by a minimisation algorithm stratified by FIGO stage, residual disease, interval between surgery and chemotherapy, and Gynecologic Cancer InterGroup group. The primary endpoint was progression-free survival; the study was also powered to detect a difference in overall survival. Analysis was by intention to treat. This trial is registered as an International Standard Randomised Controlled Trial, number ISRCTN91273375.
Between Dec 18, 2006, and Feb 16, 2009, 1528 women were enrolled and randomly assigned to receive chemotherapy (n=764) or chemotherapy plus bevacizumab (n=764). Median follow-up at the end of the trial on March 31, 2013, was 48·9 months (IQR 26·6–56·2), at which point 714 patients had died (352 in the chemotherapy group and 362 in the bevacizumab group). Our results showed evidence of non-proportional hazards, so we used the difference in restricted mean survival time as the primary estimate of effect. No overall survival benefit of bevacizumab was recorded (restricted mean survival time 44·6 months [95% CI 43·2–45·9] in the standard chemotherapy group vs 45·5 months [44·2–46·7] in the bevacizumab group; log-rank p=0·85). In an exploratory analysis of a predefined subgroup of 502 patients with poor prognosis disease, 332 (66%) died (174 in the standard chemotherapy group and 158 in the bevacizumab group), and a significant difference in overall survival was noted between women who received bevacizumab plus chemotherapy and those who received chemotherapy alone (restricted mean survival time 34·5 months [95% CI 32·0–37·0] with standard chemotherapy vs 39·3 months [37·0–41·7] with bevacizumab; log-rank p=0·03). However, in non-high-risk patients, the restricted mean survival time did not differ significantly between the two treatment groups (49·7 months [95% CI 48·3–51·1]) in the standard chemotherapy group vs 48·4 months [47·0–49·9] in the bevacizumab group; p=0·20). An updated analysis of progression-free survival showed no difference between treatment groups. During extended follow-up, one further treatment-related grade 3 event (gastrointestinal fistula in a bevacizumab-treated patient), three grade 2 treatment-related events (cardiac failure, sarcoidosis, and foot fracture, all in bevacizumab-treated patients), and one grade 1 treatment-related event (vaginal haemorrhage, in a patient treated with standard chemotherapy) were reported.
Bevacizumab, added to platinum-based chemotherapy, did not increase overall survival in the study population as a whole. However, an overall survival benefit was recorded in poor-prognosis patients, which is concordant with the progression-free survival results from ICON7 and GOG-218, and provides further evidence towards the optimum use of bevacizumab in the treatment of ovarian cancer.
The National Institute for Health Research through the UK National Cancer Research Network, the Medical Research Council, and Roche.
Journal Article
Characterizing Optical Fiber Transmission Matrices Using Metasurface Reflector Stacks for Lensless Imaging without Distal Access
by
Ramos, Alberto Gil C. P.
,
Wilkinson, Timothy D.
,
Bohndiek, Sarah E.
in
Algorithms
,
Bending
,
Calibration
2019
The ability to retrieve image data through hair-thin optical fibers promises to open up new applications in a range of fields, from biomedical imaging to industrial inspection. Unfortunately, small changes in mechanical deformation and temperature can completely scramble optical information, distorting any resulting images. Correction of these dynamic changes requires measurement of the fiber transmission matrix (TM) in situ immediately before imaging, which typically requires access to both the proximal and distal facets of the fiber simultaneously. As a result, TM calibration is not feasible during most realistic usage scenarios without compromising the thin form factor with bulky distal optics. Here, we introduce a new approach to determine the TM of multimode or multicore optical fibers in a reflection-mode configuration, without requiring access to the distal facet. We propose introducing a thin stack of structured metasurface reflectors at the distal facet of the fiber, to introduce wavelength-dependent, spatially heterogeneous reflectance profiles. We derive a first-order fiber model that compensates these wavelength-dependent changes in the fiber TM and show that, consequently, the reflected data at three wavelengths can be used to unambiguously reconstruct the full TM by an iterative optimization algorithm. Unlike previous approaches, our method does not require the fiber matrix to be unitary, making it applicable to physically realistic fiber systems that have non-negligible power loss. We demonstrate TM reconstruction and imaging first using simulated nonunitary fibers and noisy reflection matrices, then using larger experimentally measured TMs of a densely packed multicore fiber (MCF), and finally using experimentally measured multiwavelength TMs recorded from a step-index multimode fiber (MMF). Parallelization of multiwavelength in situ measurements could enable experimental characterization times comparable with state-of-the-art transmission-mode fiber TM experiments. Our findings pave the way for online TM calibration in situ in hair-thin optical fibers.
Journal Article