Community-level response of coastal microbial biofilms to ocean acidification in a natural carbon dioxide vent ecosystem.

The version on PEARL: Corrected proofs are Articles in Press that contain the authors' corrections. Final citation details, e.g., volume/issue number, publication year and page numbers, still need to be added and the text might change before final publication. Although corrected proofs do not have all bibliographic details available yet, they can already be cited using the year of online publication and the DOI , as follows: author(s), article title, journal (year), DOIThe impacts of ocean acidification on coastal biofilms are poorly understood. Carbon dioxide vent areas provide an opportunity to make predictions about the impacts of ocean acidification. We compared biofilms that colonised glass slides in areas exposed to ambient and elevated levels of pCO(2) along a coastal pH gradient, with biofilms grown at ambient and reduced light levels. Biofilm production was highest under ambient light levels, but under both light regimes biofilm production was enhanced in seawater with high pCO(2). Uronic acids are a component of biofilms and increased significantly with high pCO(2). Bacteria and Eukarya denaturing gradient gel electrophoresis profile analysis showed clear differences in the structures of ambient and reduced light biofilm communities, and biofilms grown at high pCO(2) compared with ambient conditions. This study characterises biofilm response to natural seabed CO(2) seeps and provides a baseline understanding of how coastal ecosystems may respond to increased pCO(2) levels

Effectiveness of commercial versus homemade sports drinks on fluid balance and exercise capacity during high-intensity intermittent exercise

Commercial sports drinks are used widely by athletes involved in high-intensity intermittent (HII) exercise. However, little has been reported on their relative effectiveness compared to simple homemade drink formulations. The purpose of this study was to investigate the effects of different sports drink formulations (commercial v homemade), water and no drink on fluid balance and exercise capacity during HII exercise. Twelve trained men (age: 27 ± 2.1 y) performed a 90-min HII running protocol designed to simulate activity experienced during a football match. The protocol was arranged in six 15-min stages where running speeds ranged between 55% and 120% of VO2max. The HII protocol included half-time and a run to fatigue post 90 min. Using a single-blind, randomized, cross-over design, participants ingested a preload of 5 mlkg-1 10 min before HII exercise and 3 mlkg-1 every 15 min of either Isostar® (ISO), a homemade sports drink (CHO), placebo (P) or no drink (ND). Blood lactate (Hla), blood glucose (Bgluc), heart rate (HR) and ratings of perceived exertion (RPE) were measured before, during (every 15 min) and after the 90-min HII protocol. Changes in plasma volume were measured at half-time and post 90 min. Sweat rate and fluid balance were calculated post each trial. Time to fatigue (TTF) was recorded at exhaustion. In the ND trial, TTF decreased by approximately 17%, 28% and 43% compared to P, CHO and ISO, respectively (p0.05). No differences were noted in HLa, RPE, PV or SR between the trials (p>0.05) but there were significant effects of time (p<0.05). Bgluc peaked at 30 minutes in ISO and CHO, but dropped by ~27% in ISO and by ~30% in CHO after half time. Absence of fluid ingestion surprisingly had no significant effect on altering plasma volume or decreasing sweat rate despite causing noticeable decreases in exercise capacity. The homemade drink improved exercise capacity in a similar manner to that of the commercial drink, but neither sports drink achieved superior hydration compared to water. Ingestion of exogenous carbohydrate through sports drink consumption caused an exercise-induced glycemic response when exercise was restarted after half-time. This decline in blood glucose after half-time appears to be marginally attenuated in P trial. A possible suggestion for team sports could be to drink water rather than sports drink prior to half-time period

Sediment microbial assemblage structure is modified by marine polychaete gut passage

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Active bacterioplankton community response to dissolved ‘free’ deoxyribonucleic acid (dDNA) in surface coastal marine waters

Seawater contains dissolved ‘free’ DNA (dDNA) that is part of a larger &lt;0.2 μm pool of DNA (D-DNA) including viruses and uncharacterised bound DNA. Previous studies have shown that bacterioplankton readily degrade dDNA and culture-based approaches have identified several potential dDNA-utilising taxa. This study characterised the seasonal variation in D-DNA concentrations at Station L4, a coastal marine observatory in the Western English Channel, and linked changes in concentration to cognate physicochemical and biological factors. The impact of dDNA addition on active bacterioplankton communities at Station L4 was then determined using 16S rRNA high-throughput sequencing and RNA Stable Isotope Probing (RNA SIP) with 13C-labelled diatom-derived dDNA. Compared to other major bacterioplankton orders, the Rhodobacterales actively responded to dDNA additions in amended microcosms and RNA SIP identified two Rhodobacterales populations most closely associated with the genera Halocynthiibacter and Sulfitobacter that assimilated the 13C-labelled dDNA. Here we demonstrate that dDNA is a source of dissolved organic carbon for some members of the major bacterioplankton group the Marine Roseobacter Clade. This study enhances our understanding of roles of specific bacterioplankton taxa in dissolved organic matter cycling in coastal waters with potential implications for nitrogen and phosphorus regeneration processes

Community responses to seawater warming are conserved across diverse biological groupings and taxonomic resolutions

Temperature variability is a major driver of ecological pattern, with recent changes in average and extreme temperatures having significant impacts on populations, communities and ecosystems. In the marine realm, very few experiments have manipulated temperature in situ, and current understanding of temperature effects on community dynamics is limited. We developed new technology for precise seawater temperature control to examine warming effects on communities of bacteria, microbial eukaryotes (protists) and metazoans. Despite highly contrasting phylogenies, size spectra and diversity levels, the three community types responded similarly to seawater warming treatments of +3°C and +5°C, highlighting the critical and overarching importance of temperature in structuring communities. Temperature effects were detectable at coarse taxonomic resolutions and many taxa responded positively to warming, leading to increased abundances at the community-level. Novel field-based experimental approaches are essential to improve mechanistic understanding of how ocean warming will alter the structure and functioning of diverse marine communities

Eurasian beaver activity increases water storage, attenuates flow and mitigates diffuse pollution from intensively-managed grasslands

This is the final version of the article. Available from Elsevier via the DOI in this record.Beavers are the archetypal keystone species, which can profoundly alter ecosystem structure and function through their ecosystem engineering activity, most notably the building of dams. This can have a major impact upon water resource management, flow regimes and water quality. Previous research has predominantly focused on the activities of North American beaver (Castor canadensis) located in very different environments, to the intensive lowland agricultural landscapes of the United Kingdom and elsewhere in Europe. Two Eurasian beavers (Castor fiber) were introduced to a wooded site, situated on a first order tributary, draining from intensively managed grassland. The site was monitored to understand impacts upon water storage, flow regimes and water quality. Results indicated that beaver activity, primarily via the creation of 13 dams, has increased water storage within the site (holding ca. 1000m(3) in beaver ponds) and beavers were likely to have had a significant flow attenuation impact, as determined from peak discharges (mean 30±19% reduction), total discharges (mean 34±9% reduction) and peak rainfall to peak discharge lag times (mean 29±21% increase) during storm events. Event monitoring of water entering and leaving the site showed lower concentrations of suspended sediment, nitrogen and phosphate leaving the site (e.g. for suspended sediment; average entering site: 112±72mgl(-1), average leaving site: 39±37mgl(-1)). Combined with attenuated flows, this resulted in lower diffuse pollutant loads in water downstream. Conversely, dissolved organic carbon concentrations and loads downstream were higher. These observed changes are argued to be directly attributable to beaver activity at the site which has created a diverse wetland environment, reducing downstream hydrological connectivity. Results have important implications for beaver reintroduction programs which may provide nature based solutions to the catchment-scale water resource management issues that are faced in agricultural landscapes.The Devon Beaver Project is led by Devon Wildlife Trust, monitored by the University of Exeter, and funded by Devon Wildlife Trust and Westland Countryside Stewards