Technical Note: A mobile sea-going mesocosm system - new opportunities for ocean change research

One of the great challenges in ocean change research is to understand and forecast the effects of environmental changes on pelagic communities and the associated impacts on biogeochemical cycling. Mesocosms, experimental enclosures designed to approximate natural conditions, and in which environmental factors can be manipulated and closely monitored, provide a powerful tool to close the gap between single species laboratory experiments and observational and correlative approaches applied in field surveys. Existing pelagic mesocosm systems are stationary and/or restricted to well-protected waters. To allow mesocosm experimentation in a range of hydrographic conditions and in areas considered most sensitive to ocean change, we developed a mobile, sea-going mesocosm facility, the Kiel Off-Shore Mesocosms for Future Ocean Simulations (KOSMOS). The KOSMOS platform, which can be transported and deployed by mid-sized research vessels, is designed for operation in moored and free-floating mode under low to moderate wave conditions (up to 2.5 m wave heights). It encloses a water column 2 m in diameter and 15 to 25 m deep (~50–75 m3 in volume) without disrupting the vertical structure or disturbing the enclosed plankton community. Several new developments in mesocosm design and operation were implemented to (i) minimize differences in starting conditions between mesocosms, (ii) allow for extended experimental duration, (iii) precisely determine the mesocosm volume, (iv) determine air–sea gas exchange, and (v) perform mass balance calculations. After multiple test runs in the Baltic Sea, which resulted in continuous improvement of the design and handling, the KOSMOS platform successfully completed its first full-scale experiment in the high Arctic off Svalbard (78° 56.2′ N, 11° 53.6′ E) in June/July 2010. The study, which was conducted in the framework of the European Project on Ocean Acidification (EPOCA), focused on the effects of ocean acidification on a natural plankton community and its impacts on biogeochemical cycling and air/sea exchange of climate relevant gases. This manuscript describes the mesocosm hardware, its deployment and handling, CO2 manipulation, sampling and cleaning, including some further modifications conducted based on the experiences gained during this study

EPOCA 2010 mesocosm CO2 enrichment experiment in Arctic waters

Due to its naturally low carbonate saturation states the Arctic Ocean is considered particularly vulnerable to ocean acidification. If CO2 emissions continue to rise at current rates, half of the Arctic Ocean will be undersaturated with respect to calcium carbonate and, therefore, corrosive for calcareous organisms within the next three to four decades. While recent studies have demonstrated sensitivities of some Arctic species to ocean acidification, no information is presently available on community- and ecosystem-level responses. As a first attempt to closing this gap, an off-shore mesocosm system (KOSMOS) developed at IFM-GEOMAR was deployed in the Kongsfjord off Spitsbergen - about 1000 nautical miles south of the North Pole - in June/July 2010 and was used to conduct a pelagic CO2 enrichment experiment. IFM-GEOMAR, which provided the logistics for this experiment, received support from the Greenpeace vessel M/S ESPERANZA, transporting the mesocosms and assisting during deployment and recovery. In nine 15mlong mesocosms, each enclosing about 50m3 of seawater, stepwise addition of CO2 saturated seawater was applied to achieve CO2 concentrations ranging from ca. 180 to 1400 atm. Half way through the experiment inorganic nutrients (5, 2.5, and 0.32 mol L1 nitrate, silicate, and phosphate, respectively) were added to the enclosed, nutrient-poor waters. In the framework of the EU integrated project EPOCA a team of 35 scientists from 12 institutes monitored the mesocosms over a period of 35 days. In total 45 parameters were measured daily and over 15000 samples analysed to cover aspects ranging from viral, bacterial, phytoplankton and zooplankton abundances, compositions, biomasses, and productivities, carbon and nutrient dynamics and stoichiometry, vertical particle fluxes, to the production of climate relevant gases and air/sea gas exchange. In bringing together a wide range of scientific expertise this study provides a comprehensive data set on pelagic ecosystem and biogeochemical responses to ocean acidification in Arctic waters

Prevalence, years lived with disability, and trends in anaemia burden by severity and cause, 1990–2021: findings from the Global Burden of Disease Study 2021

Background: Anaemia is a major health problem worldwide. Global estimates of anaemia burden are crucial for developing appropriate interventions to meet current international targets for disease mitigation. We describe the prevalence, years lived with disability, and trends of anaemia and its underlying causes in 204 countries and territories. Methods: We estimated population-level distributions of haemoglobin concentration by age and sex for each location from 1990 to 2021. We then calculated anaemia burden by severity and associated years lived with disability (YLDs). With data on prevalence of the causes of anaemia and associated cause-specific shifts in haemoglobin concentrations, we modelled the proportion of anaemia attributed to 37 underlying causes for all locations, years, and demographics in the Global Burden of Disease Study 2021. Findings: In 2021, the global prevalence of anaemia across all ages was 24·3% (95% uncertainty interval [UI] 23·9–24·7), corresponding to 1·92 billion (1·89–1·95) prevalent cases, compared with a prevalence of 28·2% (27·8–28·5) and 1·50 billion (1·48–1·52) prevalent cases in 1990. Large variations were observed in anaemia burden by age, sex, and geography, with children younger than 5 years, women, and countries in sub-Saharan Africa and south Asia being particularly affected. Anaemia caused 52·0 million (35·1–75·1) YLDs in 2021, and the YLD rate due to anaemia declined with increasing Socio-demographic Index. The most common causes of anaemia YLDs in 2021 were dietary iron deficiency (cause-specific anaemia YLD rate per 100 000 population: 422·4 [95% UI 286·1–612·9]), haemoglobinopathies and haemolytic anaemias (89·0 [58·2–123·7]), and other neglected tropical diseases (36·3 [24·4–52·8]), collectively accounting for 84·7% (84·1–85·2) of anaemia YLDs. Interpretation: Anaemia remains a substantial global health challenge, with persistent disparities according to age, sex, and geography. Estimates of cause-specific anaemia burden can be used to design locally relevant health interventions aimed at improving anaemia management and prevention. Funding: Bill & Melinda Gates Foundation