The effect of chlorine, heat and physical stress on entrained plankton at Koeberg Nuclear Power Station

Bibliography: pages 112-138.The large volume of seawater used for cooling at Koeberg Nuclear Power Station contains many planktonic organisms which are exposed to heat, chlorine and physical stress during their passage through the system. Phytoplankton biomass, measured as chlorophyll a, was reduced by an average of 55.32% due to entrainment, and productivity was decreased by 38.30% on average, mainly due to chlorination. Zooplankton mortality averaged 22.34% for all species and 30.52% for copepods, the dominant group. The copepod Paracartia africana was used in laboratory experiments designed to simulate entrainment. Latent mortality was monitored up to 60 hours after a 30-minute application of stress factors (physical stress was not simulated), and approximately 75% of the total mortality occurred within the 30-minute period. Male Paracartia experienced higher mortalities than females. Extrapolation of these results predicts an overall entrainment mortality (including latent mortality) of 40% for copepods and 29.04% for total zooplankton, although the latter cannot be substantiated. Plankton entrainment at Koeberg was not considered to be overly detrimental to the marine environment because of the very localised area affected, rapid dispersion of heat and chlorine, rapid regeneration times of phytoplankton and some zooplankton, low abundance of commercially important species and potential recruitment from the surrounding productive Benguela upwelling region

Metabarcoding of zooplankton to derive indicators of pelagic ecosystem status

Zooplankton play a key role in marine food webs and carbon cycling and are useful indicators of climate-related changes and ocean health in pelagic ecosystems. Zooplankton are traditionally identified to species through microscopy, but new molecular techniques have enabled the identification of individual specimens (DNA barcoding) or multiple species in the same sample (DNA metabarcoding). Metabarcoding has been tested and refined using zooplankton collected in South African waters for the first time. Challenges to the implementation of DNA-based methods to measure zooplankton biodiversity easily and routinely include an incomplete DNA barcode reference library, logistical complexity and uptake of the new technology by environmental management agencies. These challenges call for a national effort to intensify zooplankton barcoding initiatives and to effectively engage stakeholders in developing a roadmap towards application of DNA-based methods in marine environmental management

Metabarcoding of zooplankton to derive indicators of pelagic ecosystem status

Zooplankton play a key role in marine food webs and carbon cycling and are useful indicators of climate-related changes and ocean health in pelagic ecosystems. Zooplankton are traditionally identified to species through microscopy, but new molecular techniques have enabled the identification of individual specimens (DNA barcoding) or multiple species in the same sample (DNA metabarcoding). Metabarcoding has been tested and refined using zooplankton collected in South African waters for the first time. Challenges to the implementation of DNA-based methods to measure zooplankton biodiversity easily and routinely include an incomplete DNA barcode reference library, logistical complexity and uptake of the new technology by environmental management agencies. These challenges call for a national effort to intensify zooplankton barcoding initiatives and to effectively engage stakeholders in developing a roadmap towards application of DNA-based methods in marine environmental management. Significance: Metabarcoding has been successfully applied to marine zooplankton for the first time in South Africa, demonstrating its potential as a tool to generate ecosystem indicators during routine ocean observations. National barcoding efforts must be intensified to provide a comprehensive reference library of zooplankton DNA. Effective engagement with stakeholders is required to overcome logistical and policy challenges, and to provide a roadmap towards application of DNA-based methods in marine environmental management

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

Accommodating Dynamic Oceanographic Processes and Pelagic Biodiversity in Marine Conservation Planning

Pelagic ecosystems support a significant and vital component of the ocean's productivity and biodiversity. They are also heavily exploited and, as a result, are the focus of numerous spatial planning initiatives. Over the past decade, there has been increasing enthusiasm for protected areas as a tool for pelagic conservation, however, few have been implemented. Here we demonstrate an approach to plan protected areas that address the physical and biological dynamics typical of the pelagic realm. Specifically, we provide an example of an approach to planning protected areas that integrates pelagic and benthic conservation in the southern Benguela and Agulhas Bank ecosystems off South Africa. Our aim was to represent species of importance to fisheries and species of conservation concern within protected areas. In addition to representation, we ensured that protected areas were designed to consider pelagic dynamics, characterized from time-series data on key oceanographic processes, together with data on the abundance of small pelagic fishes. We found that, to have the highest likelihood of reaching conservation targets, protected area selection should be based on time-specific data rather than data averaged across time. More generally, we argue that innovative methods are needed to conserve ephemeral and dynamic pelagic biodiversity

Zooplankton adrift: investigating transportation by cyclonic eddy

<p>Eddies are important not just because they have momentum and can transfer water properties, but also because they play an important role in increasing the trophic energy available to organisms, thereby enhancing primary productivity. This study was conducted to test the ‘suitcase hypothesis’ – the inclusion of organic matter (OM), plankton and larvae within the single water mass of an eddy, which are then highly conserved and transported to another location. Here we hypothesize that particulate OM (POM) and zooplankton from the continental shelf of Madagascar become trapped as the eddy forms and are transported westwards. We analysed stable isotope signatures of POM and zooplankton from samples collected from the continental shelf (CS) as well as within an eddy that had recently formed off the south-west coast of Madagascar. There was no statistical difference in the POM isotopic signature or C/N ratios between the continental shelf or any of the eddy regions. However, some C/N ratio values could suggest that some OM from close to the coastal region could have been transported by the eddy. This was not the case for zooplankton, however, with isotopic signatures on the CS greatly differing from those in the eddy. Several factors could account for these differences including feeding behaviour or tissue turnover rate. We conclude that our study did not gather enough evidence to support (or reject) the ‘suitcase’ hypothesis, and further studies are needed in order to fully understand the transport of material, including zooplankton and larvae, by eddies.</p

Metabarcoding of zooplankton to derive indicators of pelagic ecosystem status

Zooplankton play a key role in marine food webs and carbon cycling and are useful indicators of climaterelated changes and ocean health in pelagic ecosystems. Zooplankton are traditionally identified to species through microscopy, but new molecular techniques have enabled the identification of individual specimens (DNA barcoding) or multiple species in the same sample (DNA metabarcoding). Metabarcoding has been tested and refined using zooplankton collected in South African waters for the first time. Challenges to the implementation of DNA-based methods to measure zooplankton biodiversity easily and routinely include an incomplete DNA barcode reference library, logistical complexity and uptake of the new technology by environmental management agencies. These challenges call for a national effort to intensify zooplankton barcoding initiatives and to effectively engage stakeholders in developing a roadmap towards application of DNA-based methods in marine environmental management. Significance: Metabarcoding has been successfully applied to marine zooplankton for the first time in South Africa, demonstrating its potential as a tool to generate ecosystem indicators during routine ocean observations. National barcoding efforts must be intensified to provide a comprehensive reference library of zooplankton DNA. Effective engagement with stakeholders is required to overcome logistical and policy challenges, and to provide a roadmap towards application of DNA-based methods in marine environmental management

Nutrient, Phytoplankton and Zooplankton Variability in the Indian Ocean

International audienceThis chapter provides an overview of the physical and biogeochemical factors that control spatial and temporal variability in macro-and micro-nutrient concentrations, phytoplankton biomass and production, and zooplankton biomass and grazing in the Indian Ocean. As in other ocean basins, in the Indian Ocean there is a strong connection between the physics that drives (or suppresses) nutrient delivery to the photic zone and responses of phytoplankton and zooplankton. Wind forcing during the Southwest/Southeast Monsoon (boreal summer, austral winter) is a major biogeochemical and ecological driver with broad stimulatory effects throughout many regions, including the Arabian Sea, Bay of Bengal, Seychelles Chagos Thermocline Ridge, Java, and the central/eastern subtropical gyre. In contrast, substantial stimulatory response to the Northeast/Northwest Monsoon (boreal winter, austral summer) is manifested primarily in the Arabian Sea and Bay of Bengal. In addition, there are regionally specific processes that significantly modulate the biogeochemical and ecological responses. For example, strong advective impacts and Fe/Si limitation in the Arabian Sea; freshwater and stratification in the Bay of Bengal; the influence of Indonesian Throughflow nutrient inputs, poleward transport, downwelling and seaward-propagating eddies in the southeastern Indian Ocean; and alongshorepropagating eddies, meanders, upwelling and poleward transport in the southwestern Indian Ocean. The southern subtropical gyre is extremely oligotrophic except when/where the Southeast Madagascar bloom occurs. Recommendations for future work include the need to reassess the potential effects of climate change on the biogeochemistry and ecology of the Indian Ocean basin, and motivate more planktonic food web studies

Nutrient, Phytoplankton and Zooplankton Variability in the Indian Ocean

International audienceThis chapter provides an overview of the physical and biogeochemical factors that control spatial and temporal variability in macro-and micro-nutrient concentrations, phytoplankton biomass and production, and zooplankton biomass and grazing in the Indian Ocean. As in other ocean basins, in the Indian Ocean there is a strong connection between the physics that drives (or suppresses) nutrient delivery to the photic zone and responses of phytoplankton and zooplankton. Wind forcing during the Southwest/Southeast Monsoon (boreal summer, austral winter) is a major biogeochemical and ecological driver with broad stimulatory effects throughout many regions, including the Arabian Sea, Bay of Bengal, Seychelles Chagos Thermocline Ridge, Java, and the central/eastern subtropical gyre. In contrast, substantial stimulatory response to the Northeast/Northwest Monsoon (boreal winter, austral summer) is manifested primarily in the Arabian Sea and Bay of Bengal. In addition, there are regionally specific processes that significantly modulate the biogeochemical and ecological responses. For example, strong advective impacts and Fe/Si limitation in the Arabian Sea; freshwater and stratification in the Bay of Bengal; the influence of Indonesian Throughflow nutrient inputs, poleward transport, downwelling and seaward-propagating eddies in the southeastern Indian Ocean; and alongshorepropagating eddies, meanders, upwelling and poleward transport in the southwestern Indian Ocean. The southern subtropical gyre is extremely oligotrophic except when/where the Southeast Madagascar bloom occurs. Recommendations for future work include the need to reassess the potential effects of climate change on the biogeochemistry and ecology of the Indian Ocean basin, and motivate more planktonic food web studies