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Background: The assessment of the severity and case fatality rates of coronavirus disease 2019 (COVID-19) and the determinants of its variation is essential for planning health resources and responding to the pandemic The interpretation of case fatality rates (CFRs) remains a challenge due to different biases associated with surveillance and reporting For example, rates may be affected by preferential ascertainment of severe cases and time delay from disease onset to death Using data from Spain, we demonstrate how some of these biases may be corrected when estimating severity and case fatality rates by age grouand gender, and identify issues that may affect the correct interpretation of the results Methods: Crude CFRs are estimated by dividing the total number of deaths by the total number of confirmed cases CFRs adjusted for preferential ascertainment of severe cases are obtained by assuming a uniform attack rate in all population groups, and using demography-adjusted under-ascertainment rates CFRs adjusted for the delay between disease onset and death are estimated by using as denominator the number of cases that could have a clinical outcome by the time rates are calculated A sensitivity analysis is carried out to compare CFRs obtained using different levels of ascertainment and different distributions for the time from disease onset to death Results: COVID-19 outcomes are highly influenced by age and gender Different assumptions yield different CFR values but in all scenarios CFRs are higher in old ages and males Conclusions: The procedures used to obtain the CFR estimates require strong assumptions and although the interpretation of their magnitude should be treated with caution, the differences observed by age and gender are fundamental underpinnings to inform decision-making

With a current estimate of ~1,000 million tons, mesopelagic fishes likely dominate the world total fishes biomass. However, recent acoustic observations show that mesopelagic fishes biomass could be significantly larger than the current estimate. Here we combine modelling and a sensitivity analysis of the acoustic observations from the Malaspina 2010 Circumnavigation Expedition to show that the previous estimate needs to be revised to at least one order of magnitude higher. We show that there is a close relationship between the open ocean fishes biomass and primary production, and that the energy transfer efficiency from phytoplankton to mesopelagic fishes in the open ocean is higher than what is typically assumed. Our results indicate that the role of mesopelagic fishes in oceanic ecosystems and global ocean biogeochemical cycles needs to be revised as they may be respiring ~10% of the primary production in deep waters.

Abstract Seagrass meadows are strong coastal carbon sinks of autochthonous and allochthonous carbon. The aim of this study was to assess the effect of coastal anthropogenic pressure on the variability of carbon sources in seagrass carbon sinks during the last 150 yr. We did so by examining the composition of the sediment organic carbon (C org ) stocks by measuring the δ 13 C org signature and C : N ratio in 210 Pb dated sediments of 11 Posidonia oceanica seagrass meadows around the Balearic Islands (Spain, Western Mediterranean) under different levels of human pressure. On average, the top meter sediment carbon deposits were mainly (59% ± 12%) composed by P. oceanica derived carbon whereas seston contribution was generally lower (41% ± 8%). The contribution of P. oceanica to the total sediment carbon stock was the highest (∼ 80%) in the most pristine sites whereas the sestonic contribution was the highest (∼ 40–80%) in the meadows located in areas under moderate to very high human pressure. Furthermore, an increase in the contribution of sestonic carbon and a decrease in that of seagrass derived carbon toward present was observed in most of the meadows examined, coincident with the onset of the tourism industry development and coastal urbanization in the region. Our results demonstrate a general increase of total carbon accumulation rate in P. oceanica sediments during the last century, mainly driven by the increase in sestonic C org carbon burial, which may have important implications in the long‐term carbon sink capacity of the seagrass meadows in the region examined.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 130:213-219 (1996) - doi:10.3354/meps130213 Loss-controlled phytoplankton production in nutrient-poor littoral waters of the NW Mediterranean: in situ experimental evidence Mura MP, Agustí S, del Giorgio PA, Gasol JM, Vaqué D, Duarte CM The role of losses in controlling phytoplankton biomass and production off Blanes Bay (NW Mediterranean) were examined, using insitu dialysis cultures, during a period of very low nutrient concentration. The ambient community experienced a negative net growth rate (-0.05 +/- 0.03 divisions d-1), compared to relatively high community growth rates (0.78 +/- 0.07 div. d-1) when metazoan grazers and physical losses, which appeared to be negligible, were excluded, indicating that loss rates (0.83 div. d-1) exceeded growth rates. This provided evidence that the biomass and production of the phytoplankton community was controlled by consumers, even at a time of very low nutrient concentrations. The community structure changed in response to the suppression of losses, leading to an enhanced growth of nano- and microphytoplankton, while the abundance of picoplanktonic autotrophs tended to decline slightly. Yet, the biomass attained by nano- and microphytoplankton was similar despite large differences in their initial density, indicating the existence of a resource limitation of the biomass the different groups may achieve. These results clearly provide evidence that the biomass and production of larger (&GT5 um) phytoplankton was controlled top-down by metazoan consumers, which were excluded from the dialysis bags, while picophytoplankton biomass was likely to be controlled by protists. This supports the notion that whether autotrophic production is channelled through metazoan herbivores or through the 'microbial loop' is closely dependent on the size (greater and smaller than about 5 um, respectively) of the autotrophs, and that top-down control of phytoplankton production may occur even when nutrients are very scarce. Phytoplankton . NW Mediterranean . Growth . Losses Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 130. Publication date: January 11, 1996 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1996 Inter-Research.

Black corals (Hexacorallia: Antipatharia) are a major component of mesophotic and deep marine ecosystems. Due to their preference for light deprived environments, black corals have historically been considered azooxanthellate, yet recent works have found them in association with dinoflagellates of the family Symbiodiniaceae down to 396 m depth. While corals and Symbiodiniaceae generally establish a symbiotic relationship in shallow water environments, the implications of this association is less well understood at deeper depths, where low light penetration cannot sustain efficient photosynthetic activity for the algae. However, Symbiodinaceae are not obligate autotrophs, and their capacity for heterotrophic feeding categorizes them as mixotrophs. In this study, we investigated the presence and diversity of Symbiodiniaceae associated with the deep-sea black coral Bathypathes thermophila (Antipatharia: Schizopathidae), collected from 204 to 655 m depth in the Saudi Arabian Red Sea. Using high-throughput sequencing of the ITS2 region, we report (1) the deepest record to date of Symbiodiniaceae associated with an anthozoan from 655 m, and (2) the first Red Sea record of Antipatharia in association with Symbiodiniaceae. Our analyses revealed that 14 out of 27 colonies of B. thermophila were associated with Symbiodiniaceae of the genera Cladocopium and Durusdinium . We unveiled 16 novel ITS2 type profiles, possibly unique to black corals and/or to these depths, along with seven profiles that were already known from shallow-water hard corals. No significant pattern was detected in terms of community diversity in relation to depth or sampling locality. Our study supports the existence of black corals-Symbiodiniaceae association and warrants further research to better understand the evolutionary processes and physiological mechanisms driving this association, specifically in light deprived environments.

Abstract Aim The seagrass, Posidonia oceanica is a clonal angiosperm endemic to the Mediterranean Sea. Previous studies have suggested that clonal growth is far greater than sexual recruitment and thus leads to low clonal diversity within meadows. However, recently developed microsatellite markers indicate that there are many different genotypes, and therefore many distinct clones present. The low resolution of markers used in the past limited our ability to estimate clonality and assess the individual level. New high‐resolution dinucleotide microsatellites now allow genetically distinct individuals to be identified, enabling more reliable estimation of population genetic parameters across the Mediterranean Basin. We investigated the biogeography and dispersal of P. oceanica at various spatial scales in order to assess the influence of different evolutionary factors shaping the distribution of genetic diversity in this species. Location The Mediterranean. Methods We used seven hypervariable microsatellite markers, in addition to the five previously existing markers, to describe the spatial distribution of genetic variability in 34 meadows spread throughout the Mediterranean, on the basis of an average of 35.6 (± 6.3) ramets sampled. Results At the scale of the Mediterranean Sea as a whole, a strong east–west cleavage was detected ( amova) . These results are in line with those obtained using previous markers. The new results showed the presence of a putative secondary contact zone at the Siculo‐Tunisian Strait, which exhibited high allelic richness and shared alleles absent from the eastern and western basins. F statistics (pairwise θ ranges between 0.09 and 0.71) revealed high genetic structure between meadows, both at a small scale (about 2 to 200 km) and at a medium scale within the eastern and western basins, independent of geographical distance. At the intrameadow scale, significant spatial autocorrelation in six out of 15 locations revealed that dispersal can be restricted to the scale of a few metres. Main conclusions A stochastic pattern of effective migration due to low population size, turnover and seed survival is the most likely explanation for this pattern of highly restricted gene flow, despite the importance of an a priori seed dispersal potential. The east–west cleavage probably represents the outline of vicariance caused by the last Pleistocene ice age and maintained to this day by low gene flow. These results emphasize the diversity of evolutionary processes shaping the genetic structure at different spatial scales.

Abstract This chapter reviews the mechanisms of transport and remineralization of organic matter in the dark water-columns and sediments of the oceans. Different approaches to estimating respiration rates are compared, and the discrepancies obtained by different methodologies are discussed. Finally, a respiratory carbon budget is produced for dark ocean areas, which includes vertical and lateral fluxes of organic matter. Overall, direct measurements of respiration, as well as indirect approaches, converge to suggest a total dark ocean respiration of 1.5-1.7 Pmol C/a. Carbon mass balances in the dark ocean suggest that the dark ocean receives 1.5-1.6 Pmol C/a, similar to the estimated respiration, of which >70% is in the form of sinking particles. Almost all the organic matter (~92%) is remineralized in the water column, the burial in sediments accounts for less than 1%. Mesopelagic (150-1000 m) respiration accounts for ~70% of dark ocean respiration, with average integrated rates of 3-4 mol C/m2-a, 6-8 times greater than in the bathypelagic zone. The results show that respiration in dark ocean is a major component of the carbon flux in the biosphere.