Plankton bloom controlled by horizontal stirring.

Here we show a simple mechanism in which changes in the rate of horizontal stirring by mesoscale ocean eddies can trigger or suppress plankton blooms and can lead to an abrupt change in the average plankton density. We consider a single species phytoplankton model with logistic growth, grazing and a spatially non-uniform carrying capacity. The local dynamics have multiple steady states for some values of the carrying capacity that can lead to localized blooms as fluid moves across the regions with different properties. We show that for this model even small changes in the ratio of biological timescales relative to the flow timescales can greatly enhance or reduce the global plankton productivity. Thus, this may be a possible mechanism in which changes in horizontal mixing can trigger plankton blooms or cause regime shifts in some oceanic regions. Comparison between the spatially distributed model and Lagrangian simulations considering temporal fluctuations along fluid trajectories, demonstrates that small scale transport processes also play an important role in the development of plankton blooms with a significant influence on global biomass

Investigation of model capability in capturing vertical hydrodynamic coastal processes: a case study in the north Adriatic Sea

Abstract. In this work we consider a numerical study of hydrodynamics in the coastal zone using two different models, SHYFEM (shallow water hydrodynamic finite element model) and MITgcm (Massachusetts Institute of Technology general circulation model), to assess their capability to capture the main processes. We focus on the north Adriatic Sea during a strong dense water event that occurred at the beginning of 2012. This serves as an interesting test case to examine both the models strengths and weaknesses, while giving an opportunity to understand how these events affect coastal processes, like upwelling and downwelling, and how they interact with estuarine dynamics. Using the models we examine the impact of setup, surface and lateral boundary treatment, resolution and mixing schemes, as well as assessing the importance of nonhydrostatic dynamics in coastal processes. Both models are able to capture the dense water event, though each displays biases in different regions. The models show large differences in the reproduction of surface patterns, identifying the choice of suitable bulk formulas as a central point for the correct simulation of the thermohaline structure of the coastal zone. Moreover, the different approaches in treating lateral freshwater sources affect the vertical coastal stratification. The results indicate the importance of having high horizontal resolution in the coastal zone, specifically in close proximity to river inputs, in order to reproduce the effect of the complex coastal morphology on the hydrodynamics. A lower resolution offshore is acceptable for the reproduction of the dense water event, even if specific vortical structures are missed. Finally, it is found that nonhydrostatic processes are of little importance for the reproduction of dense water formation in the shelf of the north Adriatic Sea

Investigation of model capability in capturing vertical hydrodynamic coastal processes: a case study in the north Adriatic Sea

In this work we consider a numerical study of hydrodynamics in the coastal zone using two different models, SHYFEM (shallow water hydrodynamic finite element model) and MITgcm (Massachusetts Institute of Technology general circulation model), to assess their capability to capture the main processes. We focus on the north Adriatic Sea during a strong dense water event that occurred at the beginning of 2012. This serves as an interesting test case to examine both the models strengths and weaknesses, while giving an opportunity to understand how these events affect coastal processes, like upwelling and downwelling, and how they interact with estuarine dynamics. Using the models we examine the impact of setup, surface and lateral boundary treatment, resolution and mixing schemes, as well as assessing the importance of nonhydrostatic dynamics in coastal processes. Both models are able to capture the dense water event, though each displays biases in different regions. The models show large differences in the reproduction of surface patterns, identifying the choice of suitable bulk formulas as a central point for the correct simulation of the thermohaline structure of the coastal zone. Moreover, the different approaches in treating lateral freshwater sources affect the vertical coastal stratification. The results indicate the importance of having high horizontal resolution in the coastal zone, specifically in close proximity to river inputs, in order to reproduce the effect of the complex coastal morphology on the hydrodynamics. A lower resolution offshore is acceptable for the reproduction of the dense water event, even if specific vortical structures are missed. Finally, it is found that nonhydrostatic processes are of little importance for the reproduction of dense water formation in the shelf of the north Adriatic Sea

Population dynamics in compressible flows

Organisms often grow, migrate and compete in liquid environments, as well as on solid surfaces. However, relatively little is known about what happens when competing species are mixed and compressed by fluid turbulence. In these lectures we review our recent work on population dynamics and population genetics in compressible velocity fields of one and two dimensions. We discuss why compressible turbulence is relevant for population dynamics in the ocean and we consider cases both where the velocity field is turbulent and when it is static. Furthermore, we investigate populations in terms of a continuos density field and when the populations are treated via discrete particles. In the last case we focus on the competition and fixation of one species compared to anotherComment: 16 pages, talk delivered at the Geilo Winter School 201

Oceanic biogeochemical characteristic maps identified with holistic use of satellite, model and data

This is the final published version.Ocean province level plankton community exhibit heterogeneity across Arctic, Nordic, Atlantic Gyre and Southern Ocean provinces. GreenSeas research is an international FP7 consortium that includes Arctic, Atlantic and Southern Ocean based research teams who are analysing the planktonic ecosystem. We are looking at how the planktonic ecosystem responds to environmental and climate change. Using Earth Observation monitoring data we report new results on identifying generic plankton characteristics observable at a province level, and also touch on spatial and temporal trends that are evident using a holistic analysis framework. Using advanced statistical methods this framework compares and combines Earth Observation information together with an in-situ Oceanic plankton Analytical Database and up to 40 year ocean general circulation biogeochemical model (OGCBM) time series of the equivalent plankton and sea-state measures of this system. Specifically, we outline the use of the GreenSeas Analytical Database, which is a harmonised set of Oceanic in-situ plankton and sea-state measures covering different cruises and time periods. The Analytical Database information ranges from plankton community, primary production, nutrient cycling to physical sea state temperature and salinity measures. The combined analysis utilises current, 10 year+ Earth Observations of ocean colour and sea surface temperature metrics and interprets these together with biogeochemical model outputs from PELAGOS, ERSEM & NORWECOM model runs to help identify planktonic based biomes. Generic planktonic characteristic maps that are equivalently observable in both the Earth Observations and numerical models are reported on. Both ocean surface and sub-surface signals are analysed together with relevant Analytical Database biome extracts. We present the current results of this inter-comparison & discuss challenges of identifying the province level plankton dominance with the satellite, model and data. In particular we discuss the strategic importance of systematically analysing the knowledge present in the existing key long term Oceanic observation platforms through such holistic analysis frameworks. These maps help to enhance and improve current biogeochemical models, our understanding of the plankton community structure and predictions used for future assessment of climate change

Addition of elotuzumab to lenalidomide and dexamethasone for patients with newly diagnosed, transplantation ineligible multiple myeloma (ELOQUENT-1): an open-label, multicentre, randomised, phase 3 trial

BACKGROUND: Elotuzumab plus lenalidomide and dexamethasone has shown improved progression-free and overall survival versus lenalidomide and dexamethasone in patients with relapsed or refractory multiple myeloma. We aimed to assess these regimens in patients with newly diagnosed multiple myeloma who are ineligible for haematopoietic stem-cell transplantation (HSCT). METHODS: ELOQUENT-1 is an open-label, multicentre, randomised, phase 3 trial conducted at 185 hospitals, oncology practices, and research centres in 19 countries. Eligible patients were aged 18 years or older with newly diagnosed, untreated, symptomatic myeloma and not candidates for high-dose therapy plus HSCT, and an Eastern Cooperative Oncology Group (ECOG) performance status of 2 or lower. Patients were randomly assigned (1:1) to receive elotuzumab plus lenalidomide and dexamethasone or lenalidomide and dexamethasone using an interactive voice response system, stratified by the International Staging System (ISS; stage I-II vs III), age (<75 years vs ≥75 years), and ECOG performance status (0 vs 1-2). Patients in the elotuzumab plus lenalidomide and dexamethasone group received elotuzumab administered intravenously at 10 mg/kg on days 1, 8, 15, and 22 during cycles 1 and 2, days 1 and 15 during cycles 3-18, and then at 20 mg/kg on day 1 for subsequent cycles. In both treatment groups, patients received 25 mg lenalidomide orally on days 1-21 of each cycle and 40 mg dexamethasone on days 1, 8, 15, and 22 of each cycle. The primary endpoint was progression-free survival, as per the primary definition from European Society for Blood and Marrow Transplantation criteria in all randomly assigned patients (intention-to-treat population). This study is registered with ClinicalTrials.gov, NCT01335399 (completed). FINDINGS: Between Aug 4, 2011, and June 19, 2014, 748 patients were randomly assigned (374 in each treatment group) and 742 patients received treatment (333 (90%) of 371 in the elotuzumab plus lenalidomide and dexamethasone group vs 339 (91%) of 371 in the lenalidomide and dexamethasone group discontinued treatment). The median age of patients was 73·0 years (IQR 69·0-78·0), 294 (39%) patients were 75 years or older. Most patients were White (711 [95%]) and male (412 [55%]). At a minimum follow-up of 65·3 months, the median progression-free survival was not significantly different between the groups: 31·4 months (95% CI 26·2-36·8) in the elotuzumab plus lenalidomide and dexamethasone group versus 29·5 months (23·5-34·3) in the lenalidomide and dexamethasone group (HR 0·93, 95·71% CI 0·77-1·12; stratified log-rank p=0·44). The median follow-up was 70·6 months (IQR 35·1-79·2). The most common grade 3-4 treatment-related adverse event was neutropenia (64 [17%] of 371 vs 79 [21%] of 371). Study drug toxicity was the reported cause of death in five (1%) versus four (1%) patients. INTERPRETATION: Elotuzumab plus lenalidomide and dexamethasone did not significantly improve progression-free survival versus lenalidomide and dexamethasone in patients with newly diagnosed multiple myeloma who are ineligible for HSCT. Although these data contribute to the treatment landscape, further research is needed to find ways to improve treatments in the front-line setting. FUNDING: Bristol Myers Squibb. Copyright © 2022 Elsevier Ltd. All rights reserved