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

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

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

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

What drives study-dependent differences in distance–decay relationships of microbial communities?

Aim Ecological communities that exist closer together in space are generally more compositionally similar than those far apart, as defined by the distance?decay of similarity relationship. However, recent research has revealed substantial variability in the distance?decay relationships of microbial communities between studies of different taxonomic groups, ecosystems and spatial scales and between those using different molecular methodologies (e.g., high-throughput sequencing versus molecular fingerprinting). Here, we test how these factors influence the strength of microbial distance?decay relationships, in order to draw generalizations about how microbial ?-diversity scales with space. Location Global. Time period Studies published between 2005 and 2019 (inclusive). Major taxa studied Bacteria, Archaea and microbial Eukarya. Methods We conducted a meta-analysis of microbial distance?decay relationships, using the Mantel correlation coefficient as a measure of the strength of distance?decay relationships. Our final dataset consisted of 452 data points, varying in environmental/ecological context or methodological approaches, and we used linear models to test the effects of each variable. Results Both ecological and methodological factors had significant impacts on the strength of microbial distance?decay relationships. Specifically, the strength of these relationships varied between environments and habitats, with soils showing significantly weaker distance?decay relationships than other habitats, whereas increasing spatial extents had no effect. Methodological factors, such as sequencing depth, were positively related to the strength of distance?decay relationships, and choice of dissimilarity metric was also important, with phylogenetic metrics generally giving weaker distance?decay relationships than binary or abundance-based indices. Main conclusions We conclude that widely studied microbial biogeographical patterns, such as the distance?decay relationship, vary by ecological context but are primarily distorted by methodological choices. Consequently, we suggest that by linking methodological approaches appropriately to the ecological context of a study, we can progress towards generalizable biogeographical relationships in microbial ecology

Comparison of performance of the Assessment of Spondyloarthritis International Society, the European Spondyloarthropathy Study Group and the modified New York criteria in a cohort of Chinese patients with spondyloarthritis

Early diagnosis of spondyloarthritis (SpA) is essential as anti-tumor necrosis factor therapy can achieve significant symptomatic relief and control of disease activity. This study aims to compare the clinical characteristics, disease activity, and functional status of a Chinese cohort of SpA patients who were re-classified into ankylosing spondylitis (AS) patients fulfilling the modified New York (MNY) criteria, those with undifferentiated SpA (USpA) fulfilling the European Spondyloarthropathy Study Group (ESSG) classification criteria only (USpA/ESSG) and those who fulfill Assessment of SpondyloArthritis International Society (ASAS) only (USpA/ASAS). Disease activity was evaluated by Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), severity of morning stiffness, patient global assessment, and C-reactive protein. Functional status was evaluated by Bath Ankylosing Spondylitis Functional Index (BASFI), modified Schober index, and dimension of chest expansion. One hundred and twenty-eight patients with disease duration of 16.3 ± 10.4 years were recruited. Patients in USpA/ESSG and USpA/ASAS were significantly younger (p = 0.01), had shorter disease duration (p < 0.01), and lower BASFI (p = 0.03) than established AS patients. All three groups have active disease with comparable BASDAI >3. BASFI correlated inversely with dimension of chest expansion and negatively modified Schober index in AS patients (p < 0.01) and modestly with BASDAI (r = 0.25, p < 0.01). BASFI correlated moderately with BASDAI in USpA/ESSG (r = 0.61, p < 0.01) but not with chest expansion or modified Schober index. Compared with established AS patients recognized by MNY criteria, patients fulfilling USpA defined by ESSG or ASAS criteria had earlier disease, as active disease and less irreversible functional deficit

Spontaneous Abortion and Preterm Labor and Delivery in Nonhuman Primates: Evidence from a Captive Colony of Chimpanzees (Pan troglodytes)

Preterm birth is a leading cause of perinatal mortality, yet the evolutionary history of this obstetrical syndrome is largely unknown in nonhuman primate species.We examined the length of gestation during pregnancies that occurred in a captive chimpanzee colony by inspecting veterinary and behavioral records spanning a total of thirty years. Upon examination of these records we were able to confidently estimate gestation length for 93 of the 97 (96%) pregnancies recorded at the colony. In total, 78 singleton gestations resulted in live birth, and from these pregnancies we estimated the mean gestation length of normal chimpanzee pregnancies to be 228 days, a finding consistent with other published reports. We also calculated that the range of gestation in normal chimpanzee pregnancies is approximately forty days. Of the remaining fifteen pregnancies, only one of the offspring survived, suggesting viability for chimpanzees requires a gestation of approximately 200 days. These fifteen pregnancies constitute spontaneous abortions and preterm deliveries, for which the upper gestational age limit was defined as 2 SD from the mean length of gestation (208 days).The present study documents that preterm birth occurred within our study population of captive chimpanzees. As in humans, pregnancy loss is not uncommon in chimpanzees, In addition, our findings indicate that both humans and chimpanzees show a similar range of normal variation in gestation length, suggesting this was the case at the time of their last common ancestor (LCA). Nevertheless, our data suggest that whereas chimpanzees' normal gestation length is ∼20-30 days after reaching viability, humans' normal gestation length is approximately 50 days beyond the estimated date of viability without medical intervention. Future research using a comparative evolutionary framework should help to clarify the extent to which mechanisms at work in normal and preterm parturition are shared in these species

Evidence for the h_b(1P) meson in the decay Upsilon(3S) --> pi0 h_b(1P)

Using a sample of 122 million Upsilon(3S) events recorded with the BaBar detector at the PEP-II asymmetric-energy e+e- collider at SLAC, we search for the $h_b(1P)$ spin-singlet partner of the P-wave chi_{bJ}(1P) states in the sequential decay Upsilon(3S) --> pi0 h_b(1P), h_b(1P) --> gamma eta_b(1S). We observe an excess of events above background in the distribution of the recoil mass against the pi0 at mass 9902 +/- 4(stat.) +/- 2(syst.) MeV/c^2. The width of the observed signal is consistent with experimental resolution, and its significance is 3.1sigma, including systematic uncertainties. We obtain the value (4.3 +/- 1.1(stat.) +/- 0.9(syst.)) x 10^{-4} for the product branching fraction BF(Upsilon(3S)-->pi0 h_b) x BF(h_b-->gamma eta_b).Comment: 8 pages, 4 postscript figures, submitted to Phys. Rev. D (Rapid Communications