There is a general perception that corals (and coral reefs) are highly susceptible to riverine inputs of terrigenous sediment, and that high rates of such inputs will negatively impact reef health and vitality (usually evidenced by low coral cover and/or high partial mortality rates). In coral reef settings where such inputs have been limited in the past and where corals are not adapted to deal with frequent sediment loading and reduced light penetration, this perception is likely to have considerable validity and may lead, over time, to shifts in coral community structure. However, there is an increasing body of sedimentological, geomorphological and palaeoecological data demonstrating not only long-term (>1,000 year) persistence of coral communities under conditions of high terrigenous sediment input and high turbidity, but also clear evidence of active and rapid reef-accretion. Under these conditions corals seem to be sufficiently adapted to these environmental conditions that coral cover is often high and well-developed reef structures can form. This has been demonstrated at sites in Thailand, Indonesia, Mozambique and at a range of sites along the nearshore (innermost shelf) areas of the Great Barrier Reef (GBR), Australia. An apparent paradox thus exists between the perceived negative effects of high turbidity and terrigenous sediment inputs on coral communities (which are widely referred to in the scientific literature) and the increasing sedimentary and palaeoecological evidence for historical timescale persistence of corals and of reef-building in these settings. This raises an intriguing question about coral carbonate production in these environments and about the nature of skeletal carbonate deposition. Are these coral communities able to produce reef structures, despite high terrigenoclastic sediment input and high turbidity regimes, because of particularly high coral growth and calcification rates? Little data exists from nearshore reefs of this type and there has been no attempt to quantify and compare these processes over temporal and spatial scales. This project thus aims to quantify coral extension (growth) and calcification rates, and to quantify the microskeletal characteristics (i.e., the size and density of key skeletal elements in the coral skeleton) from two of the dominant coral species associated with reef-building within nearshore, turbid-zone settings along the central GBR coastline. The focus for the research will be the two best-studied turbid-zone reefs in the region; Paluma Shoals and Lugger Shoal. Extensive datasets are available on the sedimentary environments, hydrodynamic conditions and contemporary community structures in each locality. In addition, radiocarbon (14C) date-constrained growth models exist for each site that allow data to be placed in a reliable chronological framework. Specifically, we will gather data on a massive coral species (Porites lobata) that makes a major contribution to contemporary reef-flat coral communities in both settings, and a branching coral species (Acropora pulchra) which previous research has demonstrated to have been a major framework contributor throughout the growth history of these reefs. The research will utilise novel Computerised (Axial) Tomography (CT) scanning and established Scanning Electron Microscopy (SEM) approaches to quantify coral growth rates and styles of coral skeletal deposition in these samples. Between-site comparisons will be made against data collected from the same species of Porites and Acropora that were collected from clear water sites at Low Isles during the 1928-1929 Great Barrier Reef Expedition. This extensive and well-catalogued coral repository is stored at the NHM and CT methodologies will allow us to examine the skeletal structures of these corals using non-destructive techniques.

Over the last two months there have been increasing reports of the current El Niño causing massive coral bleaching along Australia's Great Barrier Reef (GBR), with aerial surveys reporting that >90% of reefs are bleaching, and with more that 50% of corals on these reefs already dead. However, these surveys cannot assess what is happening on the nearshore turbid-zone reefs, firstly because turbidity levels inhibit aerial assessments, and secondly because there is little ecological data against which to compare change. The bleaching response of corals on these turbid-zone reefs is however of significant scientific interest. This interest relates specifically to the hypothesis that there may be particular marine environments that might act as important refugia sites from bleaching i.e., settings that are more effectively buffered from surface warming such that coral populations remain largely unaffected. Reefs forming in well-flushed, highly turbid settings are one such candidate location for these refugia. Increased bleaching resilience has been hypothesized because high particulate content in the water may limit UV stress, and because the corals may be more readily able to switch to predominantly heterotrophic feeding modes - reasons for enhanced protection from thermal stress events that were initially hypothesised in the early 2000's. However, recent modelling now provides a global-scale framework through which the spatial extent of such potential refugia can be defined. What is lacking however is any empirical field evidence definitively showing that these turbid-zone reefs are actually able to withstand major coral bleaching events. Without doubt the best studied of these turbid-zone reefs are those along the nearshore areas of the GBR, which have been the focus of intensive study by the PI and his group since 2006. This work has largely focused on assessing rates and styles of reef growth, but our most recent work has had as its central aim an assessment of the spatial extent and contemporary ecological structure of these reefs. Working at sites in the central GBR we have undertaken an unprecedented mapping and ecological surveying campaign, collecting >130 km of seafloor swath survey data and >4,500 video still quadrats. The resulting datasets have enabled us to develop high resolution maps of reef structure and ecological composition, which show that despite their narrow bathymetric extent, these reefs are characterised by a clear depth-controlled ecological zonation, and that they exhibit high live coral cover (mean: 38%, but up to ~80%). We are thus in a unique position to quantitatively assess the extent to which this major bleaching event has impacted these turbid-zone reefs, and to test the recently proposed hypothesis that such reefs may act as critical climate change refugia sites. In this project we will undertake a rapid assessment of the impacts of bleaching on the turbid-zone reefs in the vicinity of Paluma Shoals (central Halifax Bay). We will re-examine a suite of six proximal reefs using remotely-operated underwater video survey methods and collect ecological data along replicate transects across each reef. Video data will be used to determine species abundance and bleaching intensity. This will allow us to ascertain: 1) the total extent of bleaching-induced mortality; 2) the extent to which specific coral species have been impacted; and 3) any immediate impacts on the structural complexity and diversity of the reefs. We will also undertake comparable assessments at other turbid-zone reefs which have been the focus of our earlier studies e.g., further north around Dunk Island and to the south at Middle Reef- these reefs occupying similar geomorphic and sedimentary settings to the Paluma complex. The work would thus deliver not only data on the extent of turbid-zone reef bleaching, but also provide a robust test of the hypothesis that turbid-zone reefs may form critical climate change refugia sites.

For the UK to achieve net carbon neutrality by 2050, it is estimated that the mix of Greenhouse Gas Removal (GGR) technologies required will equate to ca. 35 M tonnes of carbon (MtC) p.a. Biochar can potentially make a major contribution both to this target and the adoption of farming practices described by the Committee on Climate Change (2020) to achieve a 64% reduction by 2050 in greenhouse gas emissions across agriculture, land use and peatlands by 64% from the 2017 level of 16 MtC. However, there are some significant challenges to overcome. There is limited availability of virgin wood to produce biochar and there are no large-scale production plants operating in the UK. Further, as well as economic viability and societal acceptability, there are concerns over biochar stability with initial degradation occurring over relatively short timescales. We propose to conduct the most ambitious and comprehensive demonstration programme to date involving arable and grassland, woodland, contaminated land, and where soil erosion control is required. Using over 200 tonnes of biochar, we will address uncertainties regarding the extent and scope of deployment and its stability with respect to carbon sequestration, together with quantifying effects on ecosystem services. The proposed research programme is highly inter-disciplinary, bridging engineering, geoscience, bioscience, social science and techno-economics, specifically designed to provide answers to the key challenges outlined and establish whether biochar can make a significant contribution to meet the UK's 2050 GGR target . The quantitative approach that we will adopt based on internationally leading science represents a step-change for biochar research in the UK, which has focussed primarily on agricultural benefits and not addressed the key challenges regarding carbon sequestration that are needed to reduce the uncertainty for policy development. Alternative bio-derived feedstocks that will significantly increase the production potential by >1 MtC p.a, will be identified. Two of our industrial partners, CEG and CPL operate demonstration and commercial plants, making them ideally placed to establish biochar production at scale in the UK. The extensive trials will provide a sound basis for establishing the potential for biochar deployment across agriculture, contaminated and reclaimed land and woodland, enabling regional and national scale effects to be quantified. To date, most field trials have been relatively localised and short-term. We aim to deploy char in large-scale farming and land management scenarios where the effects of 'real-world' management practices on the behaviour of char will be evaluated. Our excellent links with the farming sector, including the Agriculture and Horticulture Development Board and the National Farmers' Union, will provide the springboard to explore a wide range of stakeholder perspectives on biochar's role in GGR to aid policy development. . The Demonstrator will address concerns over environmental health and soil ecosystem service functioning and will provide the first comprehensive assessment of biochar stability in the UK and its impact on greenhouse gas soil emissions, with our international leading biological science and analytical capabilities. This will enable robust policy to be developed in which payments are based on the amount of carbon sequestered over extended timescales. Our business models will be based on our integrated life cycle and techno-economic analysis, identifying the carbon prices required to make deployment feasible and incorporating co-benefits of biochar use in agriculture. The Demonstrator will provide the Hub with all the necessary scientific, technological, environmental, economic and societal evidence to enable biochar deployment to be assessed in relation to other GGR approaches.

Many researchers in archaeology and the geosciences obtain timescales for their projects by radiocarbon dating plant or animal remains from the preserved deposits with which they work. Radiocarbon dates are not the same as calendar dates, however, and have to be corrected for variations in the radiocarbon content of the atmosphere at the time that the plant or animal lived. This conversion of radiocarbon dates to calendar ages, known as calibration, is not a straightforward correction. Calibration of radiocarbon dates can only be done by comparison to a suitable calibration curve. Such curves are based on measurements of radiocarbon in samples of known calendar age such as tree-rings, or in a less strict sense, on other types of samples where an independent method of dating can be used. For samples which grew in the ocean, such as shells and corals, a separate calibration curve is needed to account for changes in ocean water circulation which may bring up 'old' water from the ocean depths (the reservoir effect). The calibration curves have been refined periodically to provide better estimates of the calendar ages. In 2004, the IntCal Working Group constructed new calibration curves from radiocarbon dated tree-rings back to 12,400 years before present and from independently dated ocean samples, using an estimated correction for the reservoir effect, back to 26,000 years before present. Rather than simply averaging the data, these curves were constructed with statistical tools (models) that allowed for the uncertainty in the calendar ages of the samples used as well as the radiocarbon dates. At that time data beyond 26,000 years before present did not agree so no curve was provided but an estimate of how far the data sets differed from the underlying true curve was given. In the last few years a lot of research has gone into producing radiocarbon datasets from a variety of records. Many of these datasets are now in fairly good agreement so it should be possible to provide curves for estimating calendar ages back to 55,000 years before present. In addition new tree-ring records are becoming available which will improve the precision of the calibration curve. Statistical methods have also been rapidly advancing and so some of the simplifying assumptions that we made about the models in 2004 will no longer be necessary. Working in collaboration with the IntCal Working Group, this project will develop an easily maintainable database of calibration quality radiocarbon data to be used to produce updates to the calibration curves on a regular basis. Advances in statistics will allow us to improve on the previous models to further refine the calibration curves. Measurements of carefully selected coral will help determine what corrections are needed for ocean samples to be used in calibration curves. By improving radiocarbon calibration this project will improve the understanding of the sequence and timing of events in numerous studies in archaeology and in the reconstruction of past environments.

Regional-scale deteriorations in coral cover and reef architectural complexity, driven by a suite of environmental and climate-change related disturbances, have been documented, with the scale of global reef ecosystem change such that a cessation of reef accretion has been argued by many as the ultimate and imminent trajectory. One of the most pressing and fundamental challenges in coral reef science is thus to project the future for coral reefs under rapidly changing climatic and environmental conditions. Responses will likely vary region by region, and reef by reef, but will ultimately be determined by two basic sets of factors: 1) the ecology (and ecological responses to environmental change) of the key carbonate producers and eroders on a reef, because these interact to determine whether a reef has the potential to add new carbonate to its structure; and 2) the geomorphic evolutionary state and future growth potential of that reef as a function of its past growth history relative to sea level. Whilst there is an expansive and rapidly growing body of data on local and regional spatial scale contemporary ecological processes to inform this debate, there is a remarkable paucity of data on the age, growth history and morphogenetic evolutionary state of the reef structures on which these contemporary processes operate. Indeed, a review of the literature suggests that data on Holocene coral reef accretion rates (as a measure of net vertical reef growth over time) exists for something well below 1% of the World's coral reefs. This represents a major limitation in any attempts to project future rates of reef growth (and thus geomorphic change), and inherently inhibits attempts to integrate data on past rates and timescales of reef growth (at the individual reef scale) into assessments of future ecological states, and thus into management decision-making. For example, if a reef has been at sea level for the past several 100's to 1000's of years, and exists in an essentially senescent evolutionary state (a 'senile' state: sensu Hopley 1982), not only will its current habitat diversity be restricted but its immediate growth potential and its potential for sustained future growth will be severely impaired. The implications of this are clear - that the best informed management plans should integrate knowledge not only of contemporary reef ecology and habitat types but also, as a predictor of future potential geomorphic performance, an understanding of past and potential reef growth rates and of the current geomorphic evolutionary state of a reef. To address this issue, inclusive datasets are needed that can inform our understanding of: 1) when different reefs within individual regions started to grow; 2) how fast they accreted in different settings; 3) which reefs have been most actively accreting in the very recent past; and 4) which reefs, as a function of their current geomorphic state, have the greatest potential for further accretion in the future. The primary goal of this project is thus to address one part of the future reef trajectory challenge - the relevance and role of past geomorphic performance and of current reef evolutionary state as a predictor of future reef accretion potential. This has direct long-term management relevance because contemporary reef morphology is one of the key contributing factors that influences future morphology and thus the characteristics and diversity of reef habitats. Specifically, the project will develop new, spatially inclusive reef accretion and evolutionary state datasets - taking as a case site the inner-shelf regions of Australia's Great Barrier Reef. Whilst regionally focused, the work has global scale relevance because of the implications for understanding the links between reef growth histories, contemporary ecological states and future habitat complexity.