An Investigation into changes in the phytoplankton community in Loch Creran, a Scottish sea loch

Short term and irregular sampling in Loch Creran over recent decades suggested that changes may be occurring in the phytoplankton community in the loch. This study sought to confirm this suggestion. After instigating a regular sampling regime during 2008 and 2009 it became clear that significant changes had occurred, relative to information from the 1970s, in both the numbers of phytoplankton in the loch and in their biomass, particularly during the time of the spring bloom. Utilising a tool to assess change in the phytoplankton community, it also became clear that significant changes had occurred in the composition of the phytoplankton in Loch Creran. Work was undertaken to explore possible explanations behind these changes.The effect that toxic, anti-fouling compounds, arising from an increase in leisure boating in Loch Creran, were having on the productivity of phytoplankton in the loch was considered by adapting an existing assimilative capacity model for phytoplankton growth. It was found, that at present levels of boating activity, the concentration of anti-fouling products present in the loch, would not be great enough to significantly impact on phytoplankton growth.Nutrient samples collected during 2009 showed no significant changes in the concentration of silicate or nitrate in the loch, but phosphate levels were found to be significantly lower. A review of the effects of grazing on phytoplankton by farmed mussels in Loch Creran indicated that, at current levels, this would not account for the decrease in phytoplankton numbers observed in the loch.Significant changes were observed in the water temperature in the loch and in the intensity and pattern of local rainfall. Increased levels of rainfall in the first three months of the year were found to be high enough to influence the rate of flushing and the rate of phytoplankton washout from the loch. A correlation was found between the availability of light in the surface layers of the loch and the concentration of phytoplankton present in these layers. This correlation was found to exist, throughout the year and not only, as previously thought, during the winter months.In conclusion, the observed decline in phytoplankton numbers in Loch Creran, was attributed to changes in local weather patterns, that had an impact on the physical structure of the water column, washout rates, the pattern and intensity of heterotrophic grazing and the availability of light

mNCEA policy brief - Mind the Gap – The need to continue long-term plankton monitoring

This policy brief argues that while it is beneficial to explore novel plankton survey technology, it is essential that we also continue to maintain traditional long-term monitoring programmes to generate the necessary information to inform policy. Changes in plankton have important implications for the continued provision of ecosystem services, including supporting commercial fish stocks, carbon sequestration, and oxygen production. Such changes can only be detected by studying long-term, consistent plankton datasets which are needed to understand the pressures driving these changes and how we can manage them. Traditional long-term plankton monitoring relies on light microscopy to identify and count plankton taxa, with methods fully supported by national / international QA/QC standards and providing high quality trusted data. Novel technologies, including imaging and molecular methods, offer more efficient means of collecting some types of plankton data, filling targeted knowledge gaps left by traditional monitoring. However, these data are often semi-quantitative, lacking in QA/QC standards, and/or in taxonomic resolution. While these technologies are developed it remains critical to maintain the continuity of traditional plankton monitoring to inform policy assessments of important changes in biodiversity. Losing these time-series, many of which span multiple decades, would impair our ability to detect important change in pelagic habitats, as most changes cannot be detected from short-term data. This would also accelerate the loss of taxonomic expertise, already under threat globally, diminishing our UK skill-base. Novel technologies should be explored in parallel to traditional monitoring, as they can provide complementary data to support policy assessments and research, however, it is important that we do not attempt to replace traditional monitoring with new technology before it has been thoroughly integrated into long-term monitoring programmes. This project was funded by the Department for Environment, Food and Rural Affairs (Defra) as part of the marine arm of the Natural Capital and Ecosystem Assessment (NCEA) programme. The marine NCEA programme is leading the way in supporting Government ambition to integrate natural capital approaches into decision making for the marine environment. Find out more at https://www.gov.uk/government/publications/natural-capital-and-ecosystem-assessment-programme

Plankton community respiration and bacterial metabolism in a North Atlantic Shelf Sea during spring bloom development (April 2015)

Spring phytoplankton blooms are important events in Shelf Sea pelagic systems as the increase in carbon production results in increased food availability for higher trophic levels and the export of carbon to deeper waters and the sea-floor. It is usually accepted that the increase in phytoplankton abundance and production is followed by an increase in plankton respiration. However, this expectation is derived from field studies with a low temporal sampling resolution (5–15 days). In this study we have measured the time course of plankton abundance, gross primary production, plankton community respiration, respiration of the plankton size classes (>0.8 µm and 0.2–0.8 µm) and bacterial production at ≤5 day intervals during April 2015 in order to examine the phasing of plankton autotrophic and heterotrophic processes. Euphotic depth-integrated plankton community respiration increased five-fold (from 22 ± 4 mmol O2 m−2 d−1 on 4th April to 119 ± 4 mmol O2 m−2 d−1 on 15th April) at the same time as gross primary production also increased five-fold, (from 114 ± 5 to 613 ± 28 mmol C m−2 d−1). Bacterial production began to increase during the development of the bloom, but did not reach its maximum until 5 days after the peak in primary production and plankton respiration. The increase in plankton community respiration was driven by an increase in the respiration attributable to the >0.8 µm size fraction of the plankton community (which would include phytoplankton, microzooplankton and particle attached bacteria). Euphotic depth-integrated respiration of the 0.2–0.8 µm size fraction (predominantly free living bacteria) decreased and then remained relatively constant (16 ± 3 – 11 ± 1 mmol O2 m−2 d−1) between the first day of sampling (4th April) and the days following the peak in chlorophyll-a (20th and 25th April). Recent locally synthesized organic carbon was more than sufficient to fulfil the bacterial carbon requirement in the euphotic zone during this productive period. Changes in bacterial growth efficiencies (BGE, the ratio of bacterial production to bacterial carbon demand) were driven by changes in bacterial production rates increasing from 0.8 µm during the development of the spring bloom, followed 5 days later by a peak in bacterial production. In addition, the size fractionated respiration rates and high growth efficiencies suggest that free living bacteria are not the major producers of CO2 before, during and a few days after this shelf sea spring phytoplankton bloom.The Leverhulme Trust | Ref. RPG-2017-089UK Natural Environment Research Council (NERC) | Ref. NE/K00168X/1UK Natural Environment Research Council (NERC) | Ref. NE/ K001884/1UK Natural Environment Research Council (NERC) | Ref. NE/K002058/1UK Natural Environment Research Council (NERC) | Ref. NE/K001701/

Tocilizumab in patients admitted to hospital with COVID-19 (RECOVERY): a randomised, controlled, open-label, platform trial

Background: In this study, we aimed to evaluate the effects of tocilizumab in adult patients admitted to hospital with COVID-19 with both hypoxia and systemic inflammation. Methods: This randomised, controlled, open-label, platform trial (Randomised Evaluation of COVID-19 Therapy [RECOVERY]), is assessing several possible treatments in patients hospitalised with COVID-19 in the UK. Those trial participants with hypoxia (oxygen saturation <92% on air or requiring oxygen therapy) and evidence of systemic inflammation (C-reactive protein ≥75 mg/L) were eligible for random assignment in a 1:1 ratio to usual standard of care alone versus usual standard of care plus tocilizumab at a dose of 400 mg–800 mg (depending on weight) given intravenously. A second dose could be given 12–24 h later if the patient's condition had not improved. The primary outcome was 28-day mortality, assessed in the intention-to-treat population. The trial is registered with ISRCTN (50189673) and ClinicalTrials.gov (NCT04381936). Findings: Between April 23, 2020, and Jan 24, 2021, 4116 adults of 21 550 patients enrolled into the RECOVERY trial were included in the assessment of tocilizumab, including 3385 (82%) patients receiving systemic corticosteroids. Overall, 621 (31%) of the 2022 patients allocated tocilizumab and 729 (35%) of the 2094 patients allocated to usual care died within 28 days (rate ratio 0·85; 95% CI 0·76–0·94; p=0·0028). Consistent results were seen in all prespecified subgroups of patients, including those receiving systemic corticosteroids. Patients allocated to tocilizumab were more likely to be discharged from hospital within 28 days (57% vs 50%; rate ratio 1·22; 1·12–1·33; p<0·0001). Among those not receiving invasive mechanical ventilation at baseline, patients allocated tocilizumab were less likely to reach the composite endpoint of invasive mechanical ventilation or death (35% vs 42%; risk ratio 0·84; 95% CI 0·77–0·92; p<0·0001). Interpretation: In hospitalised COVID-19 patients with hypoxia and systemic inflammation, tocilizumab improved survival and other clinical outcomes. These benefits were seen regardless of the amount of respiratory support and were additional to the benefits of systemic corticosteroids. Funding: UK Research and Innovation (Medical Research Council) and National Institute of Health Research

Convalescent plasma in patients admitted to hospital with COVID-19 (RECOVERY): a randomised controlled, open-label, platform trial

Background: Many patients with COVID-19 have been treated with plasma containing anti-SARS-CoV-2 antibodies. We aimed to evaluate the safety and efficacy of convalescent plasma therapy in patients admitted to hospital with COVID-19. Methods: This randomised, controlled, open-label, platform trial (Randomised Evaluation of COVID-19 Therapy [RECOVERY]) is assessing several possible treatments in patients hospitalised with COVID-19 in the UK. The trial is underway at 177 NHS hospitals from across the UK. Eligible and consenting patients were randomly assigned (1:1) to receive either usual care alone (usual care group) or usual care plus high-titre convalescent plasma (convalescent plasma group). The primary outcome was 28-day mortality, analysed on an intention-to-treat basis. The trial is registered with ISRCTN, 50189673, and ClinicalTrials.gov, NCT04381936. Findings: Between May 28, 2020, and Jan 15, 2021, 11558 (71%) of 16287 patients enrolled in RECOVERY were eligible to receive convalescent plasma and were assigned to either the convalescent plasma group or the usual care group. There was no significant difference in 28-day mortality between the two groups: 1399 (24%) of 5795 patients in the convalescent plasma group and 1408 (24%) of 5763 patients in the usual care group died within 28 days (rate ratio 1·00, 95% CI 0·93–1·07; p=0·95). The 28-day mortality rate ratio was similar in all prespecified subgroups of patients, including in those patients without detectable SARS-CoV-2 antibodies at randomisation. Allocation to convalescent plasma had no significant effect on the proportion of patients discharged from hospital within 28 days (3832 [66%] patients in the convalescent plasma group vs 3822 [66%] patients in the usual care group; rate ratio 0·99, 95% CI 0·94–1·03; p=0·57). Among those not on invasive mechanical ventilation at randomisation, there was no significant difference in the proportion of patients meeting the composite endpoint of progression to invasive mechanical ventilation or death (1568 [29%] of 5493 patients in the convalescent plasma group vs 1568 [29%] of 5448 patients in the usual care group; rate ratio 0·99, 95% CI 0·93–1·05; p=0·79). Interpretation: In patients hospitalised with COVID-19, high-titre convalescent plasma did not improve survival or other prespecified clinical outcomes. Funding: UK Research and Innovation (Medical Research Council) and National Institute of Health Research

Mussels and yachts in Loch Fyne, Scotland:a case study of the science-policy interface

We report an application of the Science and Policy Integration for Coastal System Assessment (SPICOSA) Systems Approach Framework (SAF) to Loch Fyne, a fjord in western Scotland. The issue was the potential for conflict between shellfish aquaculture and recreational use for yachting. This was investigated by building an ecological-economic model to simulate: (1) release of modern anti-fouling compounds by recreational boats; (2) dilution of these in the upper layers of the loch by exchange with the sea; (3) their effects on photosynthesis by phytoplankton; (4) the role of phytoplankton (along with non-algal particulate matter) in providing food for mussels; (5) the growth of seeded mussels to harvest, determining (6) the cash input to farms, offset by their costs and allowing (7) the farm revenue to be compared with that from marinas used to berth the yachts. It was concluded from simulations that no noticeable effect on mussel harvest would occur (from this route) for any likely number of yachts berthed in the loch. The application took place in consultation with a local environmental forum and a small reference group of public officials; we reflect on it in the context of a 3-component schema for the science-policy interface and changes in the culture of UK science

Tracking changes to a microplankton community in a North Atlantic sea loch using the microplankton index PI(mp).

Microplankton plays a vital part in marine ecosystems and its importance has been recognised by the inclusion of microplankton community composition in regulatory frameworks such as the European Water Framework Directive and the Marine Strategy Framework Directive as an indicator of ecological status. Quantitative techniques are therefore required to assess the environmental status of the microplankton in a water body. Here we demonstrate the use of a method known as the Microplankton Index PI(mp) to evaluate changes in the microplankton community of the West coast Scottish Sea Loch Creran. Microplankton in this fjord has been studied since the 1970’s providing a data set spanning four decades. Our analysis compares an arbitrarily chosen reference period between 1979 and 1981 with a period between 2011 and 2013 and demonstrates that between these two periods community structure has changed considerably with a substantial drop in the numbers of observed diatoms accompanied by a rise in the number of autotrophic/mixotrophic dinoflagellates as well as an increase in the potentially toxin producing genus Pseudo-nitzschia and that these are related to changes in both the intensity and timing of local patterns of precipitation. The PI(mp) is shown to be a useful and robust method to visualise and quantify changes in the underlying structure of the microplankton community and is a powerful addition to the toolbox of techniques needed to determine the health of our seas

Dinophysis acuta in Scottish Coastal Waters and Its Influence on Diarrhetic Shellfish Toxin Profiles

Diarrhetic shellfish toxins produced by the dinoflagellate genus Dinophysis are a major problem for the shellfish industry worldwide. Separate species of the genus have been associated with the production of different analogues of the okadaic acid group of toxins. To evaluate the spatial and temporal variability of Dinophysis species and toxins in the important shellfish-harvesting region of the Scottish west coast, we analysed data collected from 1996 to 2017 in two contrasting locations: Loch Ewe and the Clyde Sea. Seasonal studies were also undertaken, in Loch Ewe in both 2001 and 2002, and in the Clyde in 2015. Dinophysis acuminata was present throughout the growing season during every year of the study, with blooms typically occurring between May and September at both locations. The appearance of D. acuta was interannually sporadic and, when present, was most abundant in the late summer and autumn. The Clyde field study in 2015 indicated the importance of a temperature front in the formation of a D. acuta bloom. A shift in toxin profiles of common mussels (Mytilus edulis) tested during regulatory monitoring was evident, with a proportional decrease in okadaic acid (OA) and dinophysistoxin-1 (DTX1) and an increase in dinophysistoxin-2 (DTX2) occurring when D. acuta became dominant. Routine enumeration of Dinophysis to species level could provide early warning of potential contamination of shellfish with DTX2 and thus determine the choice of the most suitable kit for effective end-product testing

The Presence of <i>Pseudo-nitzschia australis</i> in North Atlantic Aquaculture Sites, Implications for Monitoring Amnesic Shellfish Toxins

The farming of shellfish plays an important role in providing sustainable economic growth in coastal, rural communities in Scotland and acts as an anchor industry, supporting a range of ancillary jobs in the processing, distribution and exporting industries. The Scottish Government is encouraging shellfish farmers to double their economic contribution by 2030. These farmers face numerous challenges to reach this goal, among which is the problem caused by toxin-producing microplankton that can contaminate their shellfish, leading to harvesting site closure and the recall of product. Food Standards Scotland, a non-ministerial department of the Scottish Government, carries out a monitoring programme for both the toxin-producing microplankton and the toxins in shellfish flesh, with farms being closed when official thresholds for any toxin are breached. The farm remains closed until testing for the problematic toxin alone, often diarrhetic shellfish toxin (DST), shows the site to have dropped below the regulatory threshold. While this programme has proved to be robust, questions remain regarding the other toxins that may be present at a closed site. In this study, we tested archival material collected during site closures but only tested for DSTs as part of the official control monitoring. We found the presence of amnesic shellfish toxin (AST) in low concentrations in the majority of sites tested. In one case, the level of AST breached the official threshold. This finding has implications for AST monitoring programmes around Europe