Effects of increases in temperature and nutrients on phytoplankton community structure and photosynthesis in the Western English Channel

Anthropogenic climate change is exerting pressures on coastal ecosystems through increases in temperature, precipitation and ocean acidification. Phytoplankton community structure and photo-physiology are therefore adapting to these conditions. Changes in phytoplankton biomass and photosynthesis in relation to temperature and nutrient concentrations were assessed using a 14 year dataset from a coastal station in the Western English Channel (WEC). Dinoflagellate and coccolithophorid biomass exhibited a positive correlation with temperature, reaching the highest biomass at between 15 and 17°C. Diatoms showed a negative correlation with temperature, with highest biomass at 10°C. Chlorophyll a (chl a) normalised light-saturated photosynthetic rates (PBm) exhibited a hyperbolic response to increasing temperature, with an initial linear increase from 8 to 11°C, and reaching a plateau from 12°C. There was however no significant positive correlation between nutrients and phytoplankton biomass or PBm, which reflects the lag time between nutrient input and phytoplankton growth at this coastal site. The major phytoplankton groups that occurred at this site occupied distinct thermal niches, which in turn modified PBm. Increasing temperature, and higher water column stratification, was major factors in the initiation of dinoflagellates blooms at this site. Dinoflagellates blooms during summer also co-varied with silicate concentration, and acted as a tracer of dissolved inorganic nitrogen and phosphate from river run-off, which were subsequently reduced during these blooms. The data implies that increasing temperature and high river runoff during summer, will promote dinoflaglellates blooms in the WEC.

Thermogravimetric evaluation of perennial ryegrass (Lolium perenne) for the prediction of in vitro dry matter digestibility

Thermogravimetry (TG) can be used for assessing the compositional differences in grasses that relate to dry matter digestibility (DMD) determined by pepsin-cellulase assay. This investigation developed regression models for predicting DMD of herbage grass during one growing season using TG results. The calibration samples were obtained from a field trial of eight cultivars and two breeding lines. The harvested materials from five cuts were analysed by TG to identify differences in the combustion patterns within the range of 30-600 degrees C. The discrete results including weight loss, peak height, area, temperature, widths and residue of three decomposition peaks were regressed against the measured DMD values of the calibration samples. Similarly, continuous weight loss results of the same samples were also utilised to generate DMD models. The r(2) for validation of the discrete and the best continuous models were 0.90 and 0.95, respectively, and the two calibrations were validated using independent samples from 24 plots from a trial carried out in 2004. The standard error for prediction of the 24 samples by the discrete model (4.14%) was higher than that by the continuous model (2.98%). This study has shown that DMD of grass could be predicted from the TG results. The benefit of thermal analysis is the ability to detect and show changes in composition of cell wall fractions of grasses during different cuts in a year.

The effect of glycerol inclusion on broiler performance and nutrient digestibility

1. Crude glycerol from biodiesel production was offered ad libitum to broiler chickens in a 21-d feeding and digestibility trial. The study was designed as a 3*2+1 factorial design with 3 concentrations (33, 67, 100 g/kg) of glycerol from 2 sources, A and B (PRS Environmental Ltd and John Thompson and Sons Ltd) and a control diet. The diets were formulated to contain apparent metabolisable energy (AME) of 12.95 MJ/kg (assuming 14.6 MJ/kg for glycerol).

Effects of species loss and nutrients on biodiversity:Anthropogenic impacts on marine biodiversity: effects of enhanced nutrients and species loss on the biodiversity and ecosystem functioning of rocky shores

The focus of this study was to disentangle the effects of multiple stressors on biodiversity, ecosystem functioning and stability. This project examined the effects of anthropogenic increased nutrient loads on the diversity of coastal ecosystems and the effects of loss of species on ecosystem functioning. Specifically, the direct effect of sewage outfalls on benthic communities was assessed using a fully replicated survey that incorporated spatial and temporal variation. In addition, two field experiments examined the effects of loss of species at multiple trophic levels, and tested for potential interactive effects with enhanced nutrient concentration conditions on benthic assemblage structure and ecosystem functioning. This research addressed priority issues outlined in the Biodiversity Knowledge Programme for Ireland (2006) and also aimed to deliver information relevant to European Union (EU) directives (the Water Framework Directive [WFD], the Habitats Directive and the Marine Strategy Framework Directive).

Folate and vitamin B-12: friendly or enemy nutrients for the elderly

In the UK vitamin B-12, deficiency occurs in approximately 20% of adults aged >65 years. This incidence is significantly higher than that among the general population. The reported incidence invariably depends on the criteria of deficiency used, and in fact estimates rise to 24% and 46% among free-living and institutionalised elderly respectively when methylmalonic acid is used as a marker of vitamin B-12 status. The incidence of, and the criteria for diagnosis of, deficiency have drawn much attention recently in the wake of the implementation of folic acid fortification of flour in the USA. This fortification strategy has proved to be extremely successful in increasing folic acid intakes pre-conceptually and thereby reducing the incidence of neural-tube defects among babies born in the USA since 1998. However, in successfully delivering additional folic acid to pregnant women fortification also increases the consumption of folic acid of everyone who consumes products containing flour, including the elderly. It is argued that consuming additional folic acid (as 'synthetic' pteroylglutamic acid) from fortified foods increases the risk of 'masking' megaloblastic anaemia caused by vitamin B-12 deficiency. Thus, a number of issues arise for discussion. Are clinicians forced to rely on megaloblastic anaemia as the only sign of possible vitamin B-12 deficiency? Is serum vitamin B-12 alone adequate to confirm vitamin B-12 deficiency or should other diagnostic markers be used routinely in clinical practice? Is the level of intake of folic acid among the elderly (post-fortification) likely to be so high as to cure or 'mask' the anaemia associated with vitamin B-12 deficiency?.

Pathways for delivery of surface water nutrients to receptors

Diffuse contaminants can make their way into rivers via a number of different pathways, including overland flow, interflow, and shallow and deep groundwater. Identification of the key pathway(s) delivering contaminants to a receptor is important for implementing effective water management strategies. The ‘Pathways Project’, funded by the Irish Environmental Protection Agency, is developing a catchment management tool that will enable practitioners to identify the critical source areas for diffuse contaminants, and the key pathways of interest in assessing contaminant problems on a catchment and sub-catchment scale.
One of the aims of the project is to quantify the flow and contaminant loadings being delivered to the stream via each of the main pathways. Chemical separation of stream event hydrographs is being used to supplement more traditional physical hydrograph separation methods. Distinct, stable chemical signatures are derived for each of the pathway end members, and the proportion of flow from each during a rainfall event can be determined using a simple mass balance approach.
Event sampling was carried out in a test catchment underlain by poorly permeable soils and bedrock, which is predominantly used for grazing with a number of one-off rural residential houses. Results show that artificial field drainage, which includes subterranean land drains and collector drains around the perimeters of the 1 to 10 ha fields, plays an important role in the delivery of flow and nutrients to the streams in these types of hydrogeological settings.
Nitrate infiltrates with recharge and is delivered to the stream primarily via the artificial drains and the shallow groundwater pathway. Longitudinal stream profiles show that the nitrate load input is relatively uniform over the 8 km length of the stream at high flows, suggesting widespread diffuse contaminant input. In contrast, phosphorus is adsorbed in the clay-rich soil and is transported mainly via the overland flow pathway and the artificial drains. Longitudinal stream profiles for phosphorus suggest a pattern of more discrete points of phosphorus inputs, which may be related to point sources of contamination.
These techniques have application elsewhere within a toolkit of methods for determining the key pathways delivering contaminants to surface water receptors.

The prediction of intake potential and organic matter digestibility of grass silages by near infrared spectroscopy analysis of undried samples

A study was undertaken to examine a range of sample preparation and near infrared reflectance spectroscopy (NIPS) methodologies, using undried samples, for predicting organic matter digestibility (OMD g kg(-1)) and ad libitum intake (g kg(-1) W-0.75) of grass silages. A total of eight sample preparation/NIRS scanning methods were examined involving three extents of silage comminution, two liquid extracts and scanning via either external probe (1100-2200 nm) or internal cell (1100-2500 nm). The spectral data (log 1/R) for each of the eight methods were examined by three regression techniques each with a range of data transformations. The 136 silages used in the study were obtained from farms across Northern Ireland, over a two year period, and had in vivo OMD (sheep) and ad libitum intake (cattle) determined under uniform conditions. In the comparisons of the eight sample preparation/scanning methods, and the differing mathematical treatments of the spectral data, the sample population was divided into calibration (n = 91) and validation (n = 45) sets. The standard error of performance (SEP) on the validation set was used in comparisons of prediction accuracy. Across all 8 sample preparation/scanning methods, the modified partial least squares (MPLS) technique, generally minimized SEP's for both OMD and intake. The accuracy of prediction also increased with degree of comminution of the forage and with scanning by internal cell rather than external probe. The system providing the lowest SEP used the MPLS regression technique on spectra from the finely milled material scanned through the internal cell. This resulted in SEP and R-2 (variance accounted for in validation set) values of 24 (g/kg OM) and 0.88 (OMD) and 5.37 (g/kg W-0.75) and 0.77 (intake) respectively. These data indicate that with appropriate techniques NIRS scanning of undried samples of grass silage can produce predictions of intake and digestibility with accuracies similar to those achieved previously using NIRS with dried samples. (C) 1998 Elsevier Science B.V.

Speciation and distribution of arsenic and localization of nutrients in rice grains

Arsenic (As) contamination of rice grains and the generally low concentration of micronutrients in rice have been recognized as a major concern for human health. Here, we investigated the speciation and localization of As and the distribution of (micro)nutrients in rice grains because these are key factors controlling bioavailability of nutrients and contaminants. Bulk total and speciation analyses using high-pressure liquid chromatography (HPLC)-inductively coupled plasma mass spectrometry (ICP-MS) and X-ray absorption near-edge spectroscopy (XANES) was complemented by spatially resolved microspectroscopic techniques (micro-XANES, micro-X-ray fluorescence (micro-XRF) and particle induced X-ray emission (PIXE)) to investigate both speciation and distribution of As and localization of nutrients in situ. The distribution of As and micronutrients varied between the various parts of the grains (husk, bran and endosperm) and was characterized by element-specific distribution patterns. The speciation of As in bran and endosperm was dominated by As(III)-thiol complexes. The results indicate that the translocation from the maternal to filial tissues may be a bottleneck for As accumulation in the grain. Strong similarities between the distribution of iron (Fe), manganese (Mn) and phosphorus (P) and between zinc (Zn) and sulphur (S) may be indicative of complexation mechanisms in rice grains.