Environmental context determines the impact of titanium oxide and silver nanoparticles on the functioning of intertidal microalgal biofilms

Coastal environments are receiving habitats for most nanoparticle (NP) waste. Coastal sediments, into which NPs accumulate, support microalgal biofilms that provide important ecosystem processes: primary production, enhanced sediment stabilisation, and nutrient recycling. We assessed the impact of realistic concentrations of titanium oxide (TiO₂) and silver (Ag) NPs on marine microalgal biofilms and associated ecosystem processes in simulated natural conditions, by exposing natural biofilms to TiO₂ and Ag-NPs for one-month periods in outdoor tidal mesocosms under three contrasted environmental contexts (seasons). Ag-NPs had no significant effects on microalgal biomass, sediment biostabilisation potential and sediment–water oxygen and nutrient fluxes, even at concentrations (25 μg l¯¹) higher than current estimated levels (25 ng l¯¹). TiO₂-NPs had no significant effect at current expected concentrations (25 μg l¯¹), but higher concentrations (25 mg l¯¹) resulted in decreased microalgal biomass; decreased ability of biofilms to biostabilise sediment, therefore limiting their coastal protection potential; reduced primary production and modified nutrient recycling. TiO₂-NPs impacts were dependent on the environmental context: most effect was seen in winter, while no toxicity on biofilms was demonstrated in early spring. Our findings demonstrate that while Ag-NPs, being liable to dissolution into Ag+ ions under the conditions tested, are not expected to have an environmental impact if current predictions of environmental loading prevail, TiO₂-NPs may have ecological consequences in coastal environments in addition to direct impacts on microbial biomass

Patterns and drivers of carbohydrate budgets in ice algal assemblages from first year <scp>A</scp>rctic sea ice

AbstractOngoing changes in sea ice distribution will have major implications for the ecology of the Arctic Ocean. First year ice (FYI) supports abundant ice‐algae communities that produce dissolved and particulate carbohydrates, including extracellular polymeric substances (EPS), which are significant carbon sources, influence ice formation and microbial survival within sea ice, and water column carbon cycling following ice melt. Key drivers of the distribution and composition of these carbohydrates are poorly characterised. Carbohydrates and chlorophyll a concentrations were linearly related in springtime bottom FYI at 36 sites in the Canadian Archipelago region, with high levels of spatial heterogeneity. Nanoeukaryote cell density and phosphate concentration were strong drivers of total and dissolved carbohydrate and uronic acid concentrations. Particulate carbohydrates were strongly related to total bacterial abundance. Dissolved carbohydrates contributed 77% of total carbohydrate: the most abundant (51%) size fraction being dissolved carbohydrates &lt; 8 kDa in size, with dissolved EPS contributing 7% to total carbohydrate. Carbohydrate fractions differed in monosaccharide profiles; dissolved components being glucose rich; particulate EPS containing more mannose, xylose, fucose and arabinose. These profiles corresponded to those of cultured sea‐ice diatoms. Microbial abundance, silicate, nitrate and phosphate concentration and ice thickness were important environmental drivers, with thicker ice containing relatively more particulate EPS, with thinner ice containing high amounts of glucose‐rich smaller‐sized carbohydrate moieties. Changes in ice characteristics will alter the relative balance of labile and refractory carbohydrates generated within bottom ice layers, with implications for food webs and carbon turnover in the warming Arctic Ocean.</jats:p

Probiotic administration in congenital heart disease: a pilot study.

ObjectiveTo investigate the impact of probiotic Bifidobacterium longum ssp. infantis on the fecal microbiota and plasma cytokines in neonates with congenital heart disease.Study designSixteen infants with congenital heart disease were randomly assigned to receive either B. infantis (4.2 × 10(9) colony-forming units two times daily) or placebo for 8 weeks. Stool specimens from enrolled infants and from six term infants without heart disease were analyzed for microbial composition. Plasma cytokines were analyzed weekly in the infants with heart disease.ResultsHealthy control infants had increased total bacteria, total Bacteroidetes and total bifidobacteria compared to the infants with heart disease, but there were no significant differences between the placebo and probiotic groups. Plasma interleukin (IL)10, interferon (IFN)γ and IL1β levels were transiently higher in the probiotic group.ConclusionCongenital heart disease in infants is associated with dysbiosis. Probiotic B. infantis did not significantly alter the fecal microbiota. Alterations in plasma cytokines were found to be inconsistent

Strongholds of Ostrea edulis populations in estuaries in Essex, SE England and their association with traditional oyster aquaculture: evidence to support a MPA designation

The flat oyster Ostrea edulis has declined significantly in European waters since the 1850s as a result of anthropogenic activity. Ostrea edulis was designated a UK Biodiversity Action Plan Species and Habitat in 1995, and as a Feature of Conservation Importance (FOCI) within the UK Marine & Coastal Access Act 2009. To promote the recovery of oyster beds, a greater understanding of its abundance and distribution is required. Distribution of O. edulis across the proposed Blackwater, Crouch, Roach and Colne MCZ in Essex was determined between 2008 and 2012. Ostrea edulis were present in four estuary zones; with highest sample abundance in the Blackwater and Ray Sand zones. Size structure of populations varied, with the Ray Sand and Colne zones showing a significant lack of individuals with shell height <39 mm. Ostrea edulis occurred in highest number on shell substratum, followed by silty sediments. There were no significant associations between O. edulis abundance or size structure with water column Chl a, suspended solids, oxygen, nitrate or ammonium concentrations, temperature or pH. Highest abundance and most equitable population shell-size distribution for O. edulis were located within, or adjacent to, actively managed aquaculture zones. This suggests that traditional seabed management contributed to the maintenance or recovery of the species of conservation concern. Demonstration that the Essex estuaries were a stronghold for Ostrea edulis in the southern North sea area led to the designation of the Blackwater, Crouch, Roach and Colne estuaries Marine Conservation Zone in 2013

Movement of microphytobenthos and sediment between mudflats and salt marsh during spring tides

The movement of sediment and associated microphytobenthos (MPB) between the upper mudflat and salt marsh in a macrotidal estuary was investigated by comparing the variability of benthic chlorophyll a (Chl. a) and suspended Chl. a during flood and ebb spring tides during the 2015 super moon event. Sampling was carried out for four days in August and September. Flood tide water carried significantly higher amounts of Chl. a from the mudflat transition zone onto the salt marsh compared to the amount of leaving the salt marsh during ebb tides. Suspended solid loads, suspended Chl. a concentrations, and diatom species composition provided evidence that resuspended mudflat sediments containing biofilm material was transferred onto the salt marsh by flood tide. Significant negative correlations between sediment Chl. a concentrations on the upper mudflat transition zone and Chl. a concentrations in flood tide water indicated biostabilisation of sediments by biofilms reducing sediment resuspension. Mean wind speed had a significant positive effect on resuspending Chl. a from the salt marsh sediment surface into the ebb tide (p < 0.001). The amount of Chl. a being resuspended in flood and ebb tidal waters was significantly correlated with MPB biomass on the sediment surface on the mudflat and salt marsh, respectively. Resuspended diatoms over the mudflat during high tide shared a total of 54.3 % similar species with diatoms recorded in flood tidal water over the salt marsh. Diatom taxa characteristic of salt marsh assemblages, and some deposited diatom taxa were resuspended and carried off the salt marsh during ebb tide. Resuspension of Chl. a in both flood and ebb waters was significantly controlled by the tidal range (both significant at p < 0.001). During spring tides, there was a net movement of characteristic MPB mudflat diatom taxa and sediment from the adjacent mudflat to the salt marsh, contributing to the accumulation of material within vegetated marshes during summer months

The importance of weather and tides on the resuspension and deposition of microphytobenthos (MPB) on intertidal mudflats

Abiotic variables, such as weather and tidal forces, are potentially as important as biotic factors (growth, predation, competition) in driving the variability of microphytobenthic (MPB) biomass on intertidal flats. Patterns of spatial distribution and temporal variability in MPB Chl. a, sediment Extracellular Polymeric Substances (EPS) and benthic diatom species composition were investigated during daily sampling spanning neap to spring tide periods on intertidal mudflats in the Colne Estuary, U.K., in three different seasons, with a particular focus on the influence of wind, rainfall, sun hours in the days prior to sampling, and tidal range. Spatial distribution (at < 1 m and <5 m scales) made the greatest contribution to biomass variability, followed by temporal (inter-monthly) variability. MPB Chl. a and EPS concentrations were positively correlated with sun-hours and tidal range, and negatively with rainfall and wind speed. Higher benthic MPB biomass was associated with lower suspended solid and Chl a loads, indicating biostabilisation of surface sediment. Suspended sediment loads and suspended Chl. a concentrations were positively correlated, and were significantly higher during neap rather than spring tides. Sediment settlement rates were higher during neap tides and related to suspended sediment load. The percent similarity in the benthic and suspended diatom assemblages (species relative abundance, RA) increased linearly with suspended solid load, with highest similarity during neap tides, with pennate benthic diatom taxa (Gyrosigma balticum, G. scalproides and Pleurosigma angulatum) dominant, indicating local sediment resuspension. During Spring tides, species similarity was lower, with a higher RA of planktonic centric diatoms (Actinoptychus, Coscinodiscus and Odontella) and lower sediment loads. Despite greater volumes of water movement during high tidal range periods, the highest levels of localised resuspension and remobilisation of MPB biomass across the mudflats occurred during low tidal range neap tide periods, when wind-induced waves were a key factor, particularly with shallower water depths over the intertidal mudflats

Whole home exercise intervention for depression in older care home residents (the OPERA study) : a process evaluation

Background: The ‘Older People’s Exercise intervention in Residential and nursing Accommodation’ (OPERA) cluster randomised trial evaluated the impact of training for care home staff together with twice-weekly, physiotherapist-led exercise classes on depressive symptoms in care home residents, but found no effect. We report a process evaluation exploring potential explanations for the lack of effect. Methods: The OPERA trial included over 1,000 residents in 78 care homes in the UK. We used a mixed methods approach including quantitative data collected from all homes. In eight case study homes, we carried out repeated periods of observation and interviews with residents, care staff and managers. At the end of the intervention, we held focus groups with OPERA research staff. We reported our first findings before the trial outcome was known. Results: Homes showed large variations in activity at baseline and throughout the trial. Overall attendance rate at the group exercise sessions was low (50%). We considered two issues that might explain the negative outcome: whether the intervention changed the culture of the homes, and whether the residents engaged with the intervention. We found low levels of staff training, few home champions for the intervention and a culture that prioritised protecting residents from harm over encouraging activity. The trial team delivered 3,191 exercise groups but only 36% of participants attended at least 1 group per week and depressed residents attended significantly fewer groups than those who were not depressed. Residents were very frail and therefore most groups only included seated exercises. Conclusions: The intervention did not change the culture of the homes and, in the case study homes, activity levels did not change outside the exercise groups. Residents did not engage in the exercise groups at a sufficient level, and this was particularly true for those with depressive symptoms at baseline. The physical and mental frailty of care home residents may make it impossible to deliver a sufficiently intense exercise intervention to impact on depressive symptoms

Are Drivers of Root-Associated Fungal Community Structure Context Specific?

The composition and structure of plant-root-associated fungal communities are determined by local abiotic and biotic conditions. However, the relative influence and identity of relationships to abiotic and biotic factors may differ across environmental and ecological contexts, and fungal functional groups. Thus, understanding which aspects of root-associated fungal community ecology generalise across contexts is the first step towards a more predictive framework. We investigated how the relative importance of biotic and abiotic factors scale across environmental and ecological contexts using high-throughput sequencing (ca. 55 M Illumina metabarcoding sequences) of >260 plant-root-associated fungal communities from six UK salt marshes across two geographic regions (South-East and North-West England) in winter and summer. Levels of root-associated fungal diversity were comparable with forests and temperate grasslands, quadrupling previous estimates of salt-marsh fungal diversity. Whilst abiotic variables were generally most important, a range of site- and spatial scale-specific abiotic and biotic drivers of diversity and community composition were observed. Consequently, predictive models of diversity trained on one site, extrapolated poorly to others. Fungal taxa from the same functional groups responded similarly to the specific drivers of diversity and composition. Thus site, spatial scale and functional group are key factors that, if accounted for, may lead to a more predictive understanding of fungal community ecology

The OPERA trial : a protocol for the process evaluation of a randomised trial of an exercise intervention for older people in residential and nursing accommodation

Background: The OPERA trial is large cluster randomised trial testing a physical activity intervention to address depression amongst people living in nursing and residential homes for older people. A process evaluation was commissioned alongside the trial and we report the protocol for this process evaluation. Challenges included the cognitive and physical ability of the participants, the need to respect the privacy of all home residents, including study non-participants, and the physical structure of the homes. Evaluation activity had to be organised around the structured timetable of homes, leaving limited opportunities for data collection. The aims of this process evaluation are to provide findings that will assist in the interpretation of the clinical trial results, and to inform potential implementation of the physical activity intervention on a wider scale. Methods/design: Quantitative data on recruitment of homes and individuals is being collected. For homes in the intervention arm, data on dose and fidelity of the intervention delivered; including individual rates of participation in exercise classes are collected. In the control homes, uptake and delivery of depression awareness training is monitored. These data will be combined with qualitative data from an in-depth study of a purposive sample of eight homes (six intervention and two control). Discussion: Although process evaluations are increasingly funded alongside trials, it is still rare to see the findings published, and even rarer to see the protocol for such an evaluation published. Process evaluations have the potential to assist in interpreting and understanding trial results as well as informing future roll-outs of interventions. If such evaluations are funded they should also be reported and reviewed in a similar way to the trial outcome evaluation