A5069213966- Geology and Paleoclimatology Research
- Marine and coastal ecosystems
- Marine Biology and Ecology Research
- Isotope Analysis in Ecology
- Paleontology and Stratigraphy of Fossils
- Marine and environmental studies
- Geochemistry and Elemental Analysis
- Microbial Community Ecology and Physiology
- Methane Hydrates and Related Phenomena
- Arctic and Antarctic ice dynamics
- Cryospheric studies and observations
- Aquatic Ecosystems and Phytoplankton Dynamics
- Hydrocarbon exploration and reservoir analysis
- Cutaneous Melanoma Detection and Management
- Oceanographic and Atmospheric Processes
- Marine and fisheries research
- Marine Bivalve and Aquaculture Studies
- Geological Formations and Processes Exploration
- Nail Diseases and Treatments
- Geological and Geophysical Studies
- Ocean Acidification Effects and Responses
- Atmospheric and Environmental Gas Dynamics
- Ionosphere and magnetosphere dynamics
- Groundwater and Isotope Geochemistry
- Water Quality Monitoring Technologies
University of Bristol
2014-2024
The Alan Turing Institute
2024
Royal Holloway University of London
2023
London Bridge Hospital
2022-2023
Massachusetts Institute of Technology
2010-2011
The Cenomanian‐Turonian oceanic anoxic event (OAE2) is characterized by large perturbations in the oxygen and sulfur cycles of ocean, potentially resulting from changes supply (via solubility ocean circulation) marine productivity. We assess relative impact these mechanisms, comparing model experiments with a new compilation observations for seafloor dysoxia/anoxia photic zone euxinia. employed an intermediate‐complexity Earth system which accounts main dynamics biogeochemistry Cretaceous...
The Paleocene-Eocene Thermal Maximum (PETM) hyperthermal, ~ 56 million years ago (Ma), is the most dramatic example of abrupt Cenozoic global warming. During PETM surface temperatures increased between 5 and 9 °C onset likely took < 20 kyr. provides a case study impacts rapid warming on Earth system, including both hydrological associated biogeochemical feedbacks, proxy data from can provide constraints changes in warm climate hydrology simulated by general circulation models (GCMs). In this...
The marine nitrogen fixing microorganisms (diazotrophs) are a major source of to open ocean ecosystems and predicted be limited by iron in most environments. Here we use global targeted proteomic analyses on key unicellular diazotroph Crocosphaera watsonii reveal large scale diel changes its proteome, including substantial variations concentrations metalloproteins involved fixation photosynthesis, as well nocturnal flavodoxin production. daily synthesis degradation enzymes coordination with...
We examine the interplay between iron supply, concentrations and phytoplankton communities in Pacific Ocean. present a theoretical framework which considers competition for nitrogen resources to explain where fixing autotrophs (diazotrophs, require higher quotas, have slower maximum growth) can co‐exist with other phytoplankton. The also indicates that fixed be strongly controlled by local community. Together results from three‐dimensional numerical model, we characterize three distinct...
We employ a global three‐dimensional model to simulate diverse phytoplanktonic diazotrophs (nitrogen fixers) in the oceans. In model, structure of marine phytoplankton community self‐assembles from large number potentially viable physiologies. Amongst them, analogs Trichodesmium , unicellular and diatom‐diazotroph associations (DDA) are successful abundant. The simulated biogeography nitrogen fixation rates modeled compare favorably with compilation published observations, which includes...
[1] We interpret the environmental controls on global ocean diazotroph biogeography in context of a three-dimensional model with self-organizing phytoplankton community. As is observed, model's total population distributed over most oligotrophic warm subtropical and tropical waters, exception southeastern Pacific Ocean. This broadly follows temperature light constraints which are often used both field-based studies to explain distribution diazotrophs. However, suggests that habitat not...
Abstract. Southern Ocean (SO) marine primary productivity (PP) is strongly influenced by the availability of iron in surface waters, which thought to exert a significant control upon atmospheric CO2 concentrations on glacial/interglacial timescales. The zone bordering Antarctic Ice Sheet exhibits high PP and seasonal plankton blooms response light variations availability. sources stimulating elevated SO are debate. Established contributors include dust, coastal sediments/upwelling, icebergs...
ABSTRACT Once thought to be devoid of life, the Antarctic Ice Sheet is now known a dynamic reservoir organic carbon and metabolically active microbial cells. At ice-bed interface, subglacial lake sedimentary environments support low diversity populations, adapted perennial cold, anoxia lack light. The exchange water between these shallow conveys meltwaters associated sediments into coastal ocean. This, together with release iceberg-rafted debris more distal environments, could important for...
Abstract. We present an extension to the carbon-centric Grid Enabled Integrated Earth system model (cGEnIE) that explicitly accounts for growth and interaction of arbitrary number plankton species. The new package (ECOGEM) replaces implicit, flux-based parameterisation community currently employed, with resolved populations ecological dynamics. In ECOGEM, any species, ecophysiological traits (e.g. grazing rates) assigned according organism size functional group phytoplankton zooplankton) can...
Abstract Calcification and biomass production by planktonic marine organisms influences the global carbon cycle fuels ecosystems. The major calcifying plankton group coccolithophores are highly diverse, comprising ca. 250–300 extant species. However, coccolithophore size (a key functional trait) degree of calcification poorly quantified, as most our understanding this comes from a small number We generated novel reference dataset morphological traits, including cell-specific data for...
Abstract The fossil record reveals large changes in marine plankton ecosystems linked with both environmental and ecological change across the Cenozoic. An understanding of drivers these is key to carbon cycle. response past warm climates also provides a analogue for current climate change. While models are employed quantify interactions between environment biota, Earth system strongly encode our modern ecosystems. By contrast, trait‐based aim describe ecosystem terms fundamental...
The present-day marine nitrogen (N) cycle is strongly regulated by biology. Deficiencies in the availability of fixed and readily bioavailable relative to phosphate (P) surface ocean are largely corrected activity diazotrophs. This feedback system, termed “nitrostat,” thought have provided close regulation fixed-N speciation inventory P since Proterozoic. In contrast, during intervals intense deoxygenation such as Cretaceous anoxic event (OAE) 2, a few regional sedimentary δ 15 N records...
The early Aptian Oceanic Anoxic Event (OAE) 1a represents a major perturbation of the Earth's climate system and in particular carbon cycle, as evidenced by widespread preservation organic matter marine settings characteristic negative isotopic excursion (CIE) at its onset, followed broad positive CIE. contemporaneous emplacement large igneous province (LIP) is invoked trigger for OAE (and OAEs general), but this link ultimate source onset still debated. In study, we simultaneously...
Marine extreme events, such as marine heatwaves (MHW), low oxygen (LOX), and acidity extremes (OAX), must be considered alongside long-term ocean changes potential ecosystem stressors. In recent years, events have been shown to more frequent, persistent, intense in response continued warming, underlining the urgent need for understanding mechanisms compounding effects. this study, we investigate potentially significant role of coherent mesoscale eddies driving by applying an eddy- tracking...
The Messinian Salinity Crisis (MSC, 5.9-5.3 Ma) is recognised as a period of dramatic regional environmental change but it rarely considered in the interpretation global late Miocene. Following Shields &amp; Mills (2021), who showed that evaporite deposition has potential to perturb carbon cycle, we investigate temporal and spatial patterns resulting from precession-paced extraction gypsum preserved until today Mediterranean basin 3D Earth system model cGENIE. prescribed causes transient...
Abstract. Coccolithophores are globally important marine calcifying phytoplankton that utilize a haplo-diplontic life cycle. The cycle allows coccolithophores to divide in both phases and potentially expands coccolithophore niche volume. Research has, however, date largely overlooked the of has instead focused on diploid phase coccolithophores. Through synthesis analysis global scanning electron microscopy (SEM) abundance data (n=2534), we find calcified haploid generally constitute minor...
Planktonic Foraminifera are unique paleo-environmental indicators through their excellent fossil record in ocean sediments. Their distribution and diversity affected by different environmental factors including anthropogenically forced climate change. Until now, historical changes have not been fully assessed at the global scale. Here we present FORCIS (Foraminifera Response to Climatic Stress) database on foraminiferal species from 1910 until 2018 published unpublished data. The includes...
Abstract. Despite the important role of planktonic foraminifera in regulating ocean carbonate production and their unrivalled value reconstructing paleoenvironments, our knowledge on ecology is limited. A variety observational techniques such as plankton tows, sediment traps experiments have contributed to understanding ecology. But, fundamental questions around costs benefits calcification effect nutrients, temperature ecosystem structure these organisms remain unanswered. To tackle...
Abstract The 2‐methylhopanes (2‐MeHops) are molecular fossils of 2‐methylbacteriohopanepolyols (2‐MeBHPs) and among the oldest biomarkers on Earth. However, these biomarkers’ specific sources currently unexplained, including whether they reflect an expansion marine cyanobacteria. Here, we study occurrence 2‐MeBHPs genes involved in their synthesis modern bacteria explore 2‐MeHops geological record. We find that gene responsible for 2‐MeBHP ( hpnP ) is widespread cyano‐ ⍺‐proteobacteria, but...
Regional and global nitrogen fixation rates are often estimated from geochemical tracers related to N* (= NO 3 − 16PO 4 3− ). However the patterns of this tracer reflect influence numerous processes including fixation, denitrification, remineralization organic matter, variable stoichiometry, atmospheric deposition physical transport. Here we have used idealized models illustrate how preferential phosphorous may explain observed features distribution in North Atlantic Ocean, a subsurface...
Abstract Over the past several decades, oxygen minimum zones have rapidly expanded due to rising temperatures raising concerns about impacts of future climate change. One way better understand drivers behind this expansion is evaluate links between and seawater deoxygenation in especially times geologically abrupt change such as Palaeocene‐Eocene Thermal Maximum (PETM), a well‐characterized period rapid warming ~56 Ma. We developed applied novel redox proxies foraminiferal Cr isotopes (δ 53...
Planktonic Foraminifera are ubiquitous marine protozoa inhabiting the upper ocean. During life, they secrete calcareous shells, which accumulate in sediments, providing a geological record of past spatial and temporal changes their community structure. As result, provide opportunity to analyze both current historical patterns species distribution turnover this plankton group on global scale. The FORCIS project aims unlock potential by synthesizing comprehensive database abundance diversity...
Abstract. Planktic foraminifera are major marine calcifiers in the modern ocean, regulating inorganic carbon pump, and generating fossil archives of past climate change. The contain ecogroups with without spines algal symbionts, creating functional trait diversity which expands their ecological niches. Here, we incorporate symbiosis spine traits into symbiont-barren non-spinose foraminifer type EcoGEnIE to represent all extant species. We calibrated modelled new using Latin hypercube...
Abstract. We extend the ecological component (ECOGEM) of carbon-centric Grid-Enabled Integrated Earth system model (cGEnIE) to include a diatom functional group. ECOGEM represents plankton community dynamics via spectrum ecophysiological traits originally based on size and food web (phyto- zooplankton; EcoGEnIE 1.0), which we developed here account for group (EcoGEnIE 1.1). tuned 1.1, exploring range parameter values specific phytoplankton, including growth survival (18 parameters over 550...