Factors Influencing Carbon Stocks and Accumulation Rates in Eelgrass Meadows Across New England, USA.

Increasing the protection of coastal vegetated ecosystems has been suggested as one strategy to compensate for increasing carbon dioxide (CO2) in the atmosphere as the capacity of these habitats to sequester and store carbon exceeds that of terrestrial habitats. Seagrasses are a group of foundation species that grow in shallow coastal and estuarine systems and have an exceptional ability to sequester and store large quantities of carbon in biomass and, particularly, in sediments. However, carbon stocks (Corg stocks) and carbon accumulation rates (Corg accumulation) in seagrass meadows are highly variable both spatially and temporally, making it difficult to extrapolate this strategy to areas where information is lacking. In this study, Corg stocks and Corg accumulation were determined at 11 eelgrass meadows across New England, representing a range of eutrophication and exposure conditions. In addition, the environmental factors and structural characteristics of meadows related to variation in Corg stocks were identified. The objectives were accomplished by assessing stable isotopes of δ13C and δ15N as well as %C and %N in plant tissues and sediments, measuring grain size and 210Pb of sediment cores, and through assessing site exposure. Variability in Corg stocks in seagrass meadows is well predicted using commonly measured environmental variables such as grain size distribution. This study allows incorporation of data and insights for the northwest Atlantic, where few studies on carbon sequestration by seagrasses have been conducted.

Exponential increase of plastic burial in mangrove sediments as a major plastic sink.

Sequestration of plastics in sediments is considered the ultimate sink of marine plastic pollution that would justify unexpectedly low loads found in surface waters. Here, we demonstrate that mangroves, generally supporting high sediment accretion rates, efficiently sequester plastics in their sediments. To this end, we extracted microplastics from dated sediment cores of the Red Sea and Arabian Gulf mangrove (Avicennia marina) forests along the Saudi Arabian coast. We found that microplastics <0.5 mm dominated in mangrove sediments, helping explain their scarcity, in surface waters. We estimate that 50 ± 30 and 110 ± 80 metric tons of plastic may have been buried since the 1930s in mangrove sediments across the Red Sea and the Arabian Gulf, respectively. We observed an exponential increase in the plastic burial rate (8.5 ± 1.2% year-1) since the 1950s in line with the global plastic production increase, confirming mangrove sediments as long-term sinks for plastics.

Role of carbonate burial in Blue Carbon budgets.

Calcium carbonates (CaCO3) often accumulate in mangrove and seagrass sediments. As CaCO3 production emits CO2, there is concern that this may partially offset the role of Blue Carbon ecosystems as CO2 sinks through the burial of organic carbon (Corg). A global collection of data on inorganic carbon burial rates (Cinorg, 12% of CaCO3 mass) revealed global rates of 0.8 TgCinorg yr-1 and 15-62 TgCinorg yr-1 in mangrove and seagrass ecosystems, respectively. In seagrass, CaCO3 burial may correspond to an offset of 30% of the net CO2 sequestration. However, a mass balance assessment highlights that the Cinorg burial is mainly supported by inputs from adjacent ecosystems rather than by local calcification, and that Blue Carbon ecosystems are sites of net CaCO3 dissolution. Hence, CaCO3 burial in Blue Carbon ecosystems contribute to seabed elevation and therefore buffers sea-level rise, without undermining their role as CO2 sinks.

Impact of mooring activities on carbon stocks in seagrass meadows.

Boating activities are one of the causes that threaten seagrass meadows and the ecosystem services they provide. Mechanical destruction of seagrass habitats may also trigger the erosion of sedimentary organic carbon (Corg) stocks, which may contribute to increasing atmospheric CO2. This study presents the first estimates of loss of Corg stocks in seagrass meadows due to mooring activities in Rottnest Island, Western Australia. Sediment cores were sampled from seagrass meadows and from bare but previously vegetated sediments underneath moorings. The Corg stores have been compromised by the mooring deployment from 1930s onwards, which involved both the erosion of existing sedimentary Corg stores and the lack of further accumulation of Corg. On average, undisturbed meadows had accumulated ~6.4 Kg Corg m(-2) in the upper 50 cm-thick deposits at a rate of 34 g Corg m(-2) yr(-1). The comparison of Corg stores between meadows and mooring scars allows us to estimate a loss of 4.8 kg Corg m(-2) in the 50 cm-thick deposits accumulated over ca. 200 yr as a result of mooring deployments. These results provide key data for the implementation of Corg storage credit offset policies to avoid the conversion of seagrass ecosystems and contribute to their preservation.

Infección nosocomial en la Unidad Cuidados Intensivos / Nosocomial infection in the Intensive Care Unit

Se realizó un estudio descriptivo longitudinal con el objetivo de describir el comportamiento de la infección nosocomial en pacientes egresados de la Unidad de Cuidados Intensivos del hospital provincial universitario «Carlos Manuel de Céspedes», de Bayamo, desde el 1ro de enero de 1999 hasta el 31 de diciembre del 2000. De 1418 pacientes egresados, 110 (7,7%) cumplieron los criterios de infección nosocomial. Se seleccionaron variables tales como: edad, sexo, factores de riesgos, principales localizaciones, gérmenes frecuentes, tiempo de aparición de la infección y evolución final. En el análisis estadístico se utilizaron medidas de tendencia central y dispersión, así como los intervalos de confianza al 95% para la media. Existió discreto predominio de la infección en el grupo de45 a 59 años, con una media de 51,14 años. La línea venosa central (19,60%), sonda vesical (18,30%) y sonda de levine (13,72%) constituyeron los factores de riesgo principales. Las localizaciones más frecuentes de infección fueron las respiratorias bajas (36,23%) y las urinarias(25,19%). Existió predominio de los gérmenes gramnegativos, entre ellos el enterobacter sp. (35,09%) y la Escherichiacoli (23,07%). La infección apareció entre el segundo y el sexto día (en el 66,3%) y fallecieron el 20,9% delos pacientes que la adquirieron

A longitudinal descriptive study was done with the objective of describing the behaviour of nosocomial infection inpatients discharged from the Intensive Care Unit at «Carlos Manuel de Cespedes» universitary provincial hospital, in Bayamo, from january 1st 1999 to december 31st,2000. From 1418 discharged patients, 110 had criteria of nosocomial infections. Variables such as age, sex, risk factors, principal location, most frequent germs, time of appearance and final evaluation were selected. In the statiscal analysis measures of central tendency and dispersion, as well as intervals of reliance to 95% for the media among others were used. The rate of nosocomial infection was 7, 7 per 100 discharged patients. There was a discreet predominant infection in the 45–59 year-old group whit a media of 51-14 years. The presence of central venous line (19, 60%), vesical catheter (18, 30%)and nasogástrica tube (13, 72%) constituted the main risk factors. The most frequent location of infection were the low respiratory (36, 23%) and the urinaries (25,19%).There was a prevalence of gramnegative germs among them, enterobacter sp (35,09%), escherichiacoli (23,07%) and Proteus sp (21, 15%). The infection appeared between the second and the sixth day in (66, 3%) and20,9% of the patients who adquired the infection died