Elevated Nutrient Levels Research Articles

Local and regional disturbances associated with the invasion of Chesapeake Bay marshes by the common reed Phragmites australis

The invasion of wetlands by Phragmites australis is a conservation concern across North America. We used the invasion of Chesapeake Bay wetlands by P. australis as a model system to examine the effects of regional and local stressors on plant invasions. We summarized digital maps of the distributions of P. australis and of potential stressors (especially human land use and shoreline armoring) at two spatial scales: for 72 subestuaries of the bay and their local watersheds and for thousands of 500 m shoreline segments. We developed statistical models that use the stressor variables to predict P. australis prevalence (% of shoreline occupied) in subestuaries and its presence or absence in 500 m segments of shoreline. The prevalence of agriculture was the strongest and most consistent predictor of P. australis presence and abundance in Chesapeake Bay, because P. australis can exploit the resulting elevated nutrient levels to enhance its establishment, growth, and seed production. Phragmites australis was also positively associated with riprapped shoreline, probably because it creates disturbances that provide colonization opportunities. The P. australis invasion was less severe in areas with greater forested land cover and natural shorelines. Surprisingly, invasion was low in highly developed watersheds and highest along shorelines with intermediate levels of residential land use, possibly indicating that highly disturbed systems are uninhabitable even to invasive species. Management strategies that reduce nutrient pollution, preserve natural shorelines, and limit nearshore disturbance of soils and vegetation may enhance the resilience of shorelines to invasion.

Phytoplankton dynamics in a subtropical lake dominated by cyanobacteria: cyanobacteria ‘Like it Hot’ and sometimes dry

An 18-year data set (1993–2010) of water column variables from Lake George, Florida (USA), was used to examine relationships between the phytoplankton community (composition and biomass) and physical variables (temperature and hydrologic discharge rates). Lake George is a large shallow eutrophic lake located in the subtropical environment of north Florida and is subject to frequent and intense blooms of cyanobacteria. Cyanobacteria dominated the phytoplankton community during warmer months of the year (May–September). Other phytoplankton taxa increased their relative contributions to phytoplankton biomass during the colder months (November–March), when cyanobacterial biomass was low. Increased discharge rates during the peak flushing season (September–December) were correlated to diminished cyanobacterial biomass despite elevated nutrient levels. Analysis of time series data revealed higher warm season peaks in cyanobacteria biomass during years of relatively low discharge, whereas other phytoplankton groups showed the opposite trend with peaks during the colder months. These observations indicate a need for lake management strategies that consider both hydrologic and nutrient loadings within the context of possible future changes in temperature and rainfall regimes.

16S rRNA assessment of the influence of shading on early-successional biofilms in experimental streams.

Elevated nutrient levels can lead to excessive biofilm growth, but reducing nutrient pollution is often challenging. There is therefore interest in developing control measures for biofilm growth in nutrient-rich rivers that could act as complement to direct reductions in nutrient load. Shading of rivers is one option that can mitigate blooms, but few studies have experimentally examined the differences in biofilm communities grown under shaded and unshaded conditions. We investigated the assembly and diversity of biofilm communities using in situ mesocosms within the River Thames (UK). Biofilm composition was surveyed by 454 sequencing of 16S amplicons (∼400 bp length covering regions V6/V7). The results confirm the importance of sunlight for biofilm community assembly; a resource that was utilized by a relatively small number of dominant taxa, leading to significantly less diversity than in shaded communities. These differences between unshaded and shaded treatments were either because of differences in resource utilization or loss of diatom-structures as habitats for bacteria. We observed more co-occurrence patterns and network interactions in the shaded communities. This lends further support to the proposal that increased river shading can help mitigate the effects from macronutrient pollution in rivers.

Algae alleviate carbon limitation of heterotrophic bacteria in a boreal peatland

Summary In most high‐latitude wetlands, carbon accumulation as peat represents a balance between plant net primary productivity and heterotrophic decomposition. We hypothesized that this assessment of ecosystem metabolism is incomplete as it does not include information on energy inputs from microalgae, which form complex biofilms with heterotrophic micro‐organisms on the peat surface. To investigate the potential for algae (and associated exudates) to support heterotrophic metabolism under ambient and elevated nutrient levels, we conducted a factorial enrichment of nutrients (nitrogen and phosphorus) and carbon (glucose) in mesocosms with and without the presence of algae (using light‐transparent and dark treatments, respectively) in an Alaskan fen. We measured respiration rates and changes in bacterial biomass to characterize the response of heterotrophic bacteria to our experimental treatments. During incubation assays, algae released up to 38% of their net productivity as exudates and there was a positive relationship between algal production and concentrations of dissolved organic carbon inside mesocosms. Elevated algal productivity in the presence of nutrient enrichment stimulated heterotrophic bacterial respiration and biomass. These responses did not occur with nutrient enrichment in the dark (without algae). The response of bacteria to algae was similar in magnitude to bacterial responses to glucose enrichment. Synthesis. We conclude that bacteria in this boreal fen were primarily limited by labile carbon, and this constraint was alleviated in the presence of elevated algal production. Consequently, algae may facilitate hotspots of microbial activity in northern peatlands, especially in conditions of greater nutrient availability associated with more variable hydrology expected for this region with ongoing climate change.

Glucose-dependent acetylation of Rictor promotes targeted cancer therapy resistance

Cancer cells adapt their signaling in response to nutrient availability. To uncover the mechanisms regulating this process and its functional consequences, we interrogated cell lines, mouse tumor models, and clinical samples of glioblastoma (GBM), the highly lethal brain cancer. We discovered that glucose or acetate is required for epidermal growth factor receptor vIII (EGFRvIII), the most common growth factor receptor mutation in GBM, to activate mechanistic target of rapamycin complex 2 (mTORC2) and promote tumor growth. Glucose or acetate promoted growth factor receptor signaling through acetyl-CoA-dependent acetylation of Rictor, a core component of the mTORC2 signaling complex. Remarkably, in the presence of elevated glucose levels, Rictor acetylation is maintained to form an autoactivation loop of mTORC2 even when the upstream components of the growth factor receptor signaling pathway are no longer active, thus rendering GBMs resistant to EGFR-, PI3K (phosphoinositide 3-kinase)-, or AKT (v-akt murine thymoma viral oncogene homolog)-targeted therapies. These results demonstrate that elevated nutrient levels can drive resistance to targeted cancer treatments and nominate mTORC2 as a central node for integrating growth factor signaling with nutrient availability in GBM.

Between and within paddock soil chemical variability and forage production gradients in grazed dairy pastures

Soil chemical properties are likely to be unevenly distributed within grazed dairy farms. Paddocks that dairy cows graze more frequently, or parts of paddocks that they regularly visit potentially have elevated nutrient levels due to the excreta returned by the herd. We measured the between and within paddock distribution of a range of agronomic soil chemical properties on four commercial dairy farms. Between paddock spatial variability was high for most properties and varied between the farms (range in CV of 13–127 %). Aluminium had the widest range in CV (50–127 %) while oxidisable organic C was similar between farms (22–25 %). Only plant available K was greater at the front than at the back of the paddocks on these farms, with a trend towards higher levels at the front observed for the strip grazed farms. The impact of strip grazing on within paddock soil nutrient and pasture growth distribution was further investigated in an experimental farmlet study. Significantly greater Colwell K, EC and increased pasture production were observed in the front of strip grazed paddocks compared with the back, while soil pH and KCl-S levels were similar at both ends. The gradient of nutrients from the front to the back of these paddocks was greater in the more intensive (higher stocking rate and P fertiliser rate) systems. Soil sampling and fertiliser application strategies are needed that address nutrient variability between and within paddocks, as influenced by differences in paddock management and animal excreta distribution.

Microbial community development on the surface of Hans and Werenskiold Glaciers (Svalbard, Arctic): a comparison.

Surface ice and cryoconite holes of two types of polythermal Svalbard Glaciers (Hans Glacier—grounded tidewater glacier and Werenskiold Glacier—land-based valley glacier) were investigated in terms of chemical composition, microbial abundance and diversity. Gathered data served to describe supraglacial habitats and to compare microbe–environment interactions on those different type glaciers. Hans Glacier samples displayed elevated nutrient levels (DOC, nitrogen and seston) compared to Werenskiold Glacier. Adjacent tundra formations, bird nesting sites and marine aerosol were candidates for allochtonic enrichment sources. Microbial numbers were comparable on both glaciers, with surface ice containing cells in the range of 104 mL−1 and cryoconite sediment 108 g−1 dry weight. Denaturating gradient gel electrophoresis band-based clustering revealed differences between glaciers in terms of dominant bacterial taxa structure. Microbial community on Werenskiold Glacier benefited from the snow-released substances. On Hans Glacier, this effect was not as pronounced, affecting mainly the photoautotrophs. Over-fertilization of Hans Glacier surface was proposed as the major factor, desensitizing the microbial community to the snow melt event. Nitrogen emerged as a limiting factor in surface ice habitats, especially to Eukaryotic algae.Electronic supplementary materialThe online version of this article (doi:10.1007/s00792-015-0764-z) contains supplementary material, which is available to authorized users.

Calculating discharge of phosphorus and nitrogen with groundwater base flow to a small urban stream reach

Summary Elevated levels of nutrients, especially phosphorus, in urban streams can lead to eutrophication and general degradation of stream water quality. Contributions of phosphorus from groundwater have typically been assumed minor, though elevated concentrations have been associated with riparian areas and urban settings. The objective of this study was to investigate the importance of groundwater as a pathway for phosphorus and nitrogen input to a gaining urban stream. The stream at the 28-m study reach was 3–5 m wide and straight, flowing generally eastward, with a relatively smooth bottom of predominantly sand, with some areas of finer sediments and a few boulders. Temperature-based methods were used to estimate the groundwater flux distribution. Detailed concentration distributions in discharging groundwater were mapped using in-stream piezometers and diffusion-based peepers, and showed elevated levels of soluble reactive phosphorus (SRP) and ammonium compared to the stream (while nitrate levels were lower), especially along the south bank, where groundwater fluxes were lower and geochemically reducing conditions dominated. Field evidence suggests the ammonium may originate from nearby landfills, but that local sediments likely contribute the SRP. Ammonium and SRP mass discharges with groundwater were then estimated as the product of the respective concentration distributions and the groundwater flux distribution. These were determined as approximately 9 and 200 g d−1 for SRP and ammonium, respectively, which compares to stream mass discharges over the observed range of base flows of 20–1100 and 270–7600 g d−1, respectively. This suggests that groundwater from this small reach, and any similar areas along Dyment’s Creek, has the potential to contribute substantially to the stream nutrient concentrations.

The role of maternal obesity in the risk of neuropsychiatric disorders.

Recent evidence indicates that perinatal exposure to maternal obesity, metabolic disease, including diabetes and hypertension, and unhealthy maternal diet has a long-term impact on offspring behavior and physiology. During the past three decades, the prevalence of both obesity and neuropsychiatric disorders has rapidly increased. Epidemiologic studies provide evidence that maternal obesity and metabolic complications increase the risk of attention deficit hyperactivity disorder (ADHD), autism spectrum disorders, anxiety, depression, schizophrenia, eating disorders (food addiction, anorexia nervosa, and bulimia nervosa), and impairments in cognition in offspring. Animal models of maternal high-fat diet (HFD) induced obesity also document persistent changes in offspring behavior and impairments in critical neural circuitry. Animals exposed to maternal obesity and HFD consumption display hyperactivity, impairments in social behavior, increased anxiety-like and depressive-like behaviors, substance addiction, food addiction, and diminished cognition. During development, these offspring are exposed to elevated levels of nutrients (fatty acids, glucose), hormones (leptin, insulin), and inflammatory factors (C-reactive protein, interleukin, and tumor necrosis factor). Such factors appear to permanently change neuroendocrine regulation and brain development in offspring. In addition, inflammation of the offspring brain during gestation impairs the development of neural pathways critical in the regulation of behavior, such as serotoninergic, dopaminergic, and melanocortinergic systems. Dysregulation of these circuits increases the risk of mental health disorders. Given the high rates of obesity in most developed nations, it is critical that the mechanisms by which maternal obesity programs offspring behavior are thoroughly characterized. Such knowledge will be critical in the development of preventative strategies and therapeutic interventions.

Assessment of tillage effects on soil quality of pastures in South Africa with indexing methods

Soil quality of pastures changes through time because of management practices. Excessive soil disturbance usually leads to the decline in soil quality, and this has resulted in concerns about kikuyu (Pennisetum clandestinum)–ryegrass (Lolium spp.) pasture systems in the southern Cape region of South Africa. This study aimed to understand the effects of tillage on soil quality. The soil management assessment framework (SMAF) and the locally developed soil quality index for pastures (SQIP) were used to assess five tillage systems and were evaluated at a scale inclusive of variation in topography, pedogenic characteristics and local anthropogenic influences. Along with assessment of overall soil quality, the quality of the physical, chemical and biological components of soil were considered individually. Soil physical quality was largely a function of inherent pedogenic characteristics but tillage affected physical quality adversely. Elevated levels of certain nutrients may be warning signs to soil chemical degradation; however, tillage practice did not affect soil chemical quality. Soil disturbance and the use of herbicides to establish annual pastures has lowered soil biological quality. The SQIP was a more suitable tool than SMAF for assessing soil quality of high-input, dairy-pasture systems. SQIP could facilitate adaptive management by land managers, environmentalists, extension officers and policy makers to assess soil quality and enhance understanding of processes affecting soil quality.

Increasing algal biomass in Lake Vänern despite decreasing phosphorus concentrations: A lake-specific phenomenon?

Algal blooms in lake waters are frequently associated with elevated nutrient levels, in particular phosphorus. Here we show, with long-term data from Sweden’s largest lake, Lake Vänern, that total phytoplankton biomass has significantly increased since the 1980s at the same time as total phosphorus and inorganic nitrogen concentrations have significantly decreased (non-parametric Mann-Kendall test: P < 0.01). Lake Vänern was not the only lake showing such a pattern: evaluating long-term data from 13 small oligotrophic reference lakes revealed the same pattern. Other synchronous changes observed in Sweden’s oligotrophic lakes included strongly decreasing sulfate concentrations and increasing water temperatures. We found that alkalinity, water temperatures, silica and sulfate concentrations were the strongest predictors for total phytoplankton biomass at all three sites in Lake Vänern when we used partial least squares regression models with 11 input variables. From our results, we suggest that decreasing acidity in combination with increasing water temperatures has been more important for phytoplankton growth than total phosphorous and nitrogen concentrations. Thus, we conclude that phytoplankton biomass in oligotrophic small and large lakes is strongly associated with climate and atmospheric depositional changes, and consequently needs to be managed beyond catchment scales.

Termitaria as preferred browsing patches for black rhinoceros (Diceros bicornis) in Chipinge Safari Area, Zimbabwe

Abstract:This study tested the hypothesis that the black rhinoceros browses more on termitaria than off termitaria vegetation due to elevated soil and foliar nutrient levels on termitaria. We investigated the role of termitaria in providing nutrient-rich forage for the black rhinoceros, by comparing the preference (selection ratio) for vegetation occurring on and off termitaria, and then testing its relationship with foliar nutrient concentrations. Soil nutrients, bite intensity, tree species diversity, vegetation density, canopy cover and basal area were also surveyed on and off termitaria. We sampled 25 termite mounds together with their corresponding control plots in Chipinge Safari Area, Zimbabwe. Soil and foliar N, P, K, Ca and Na concentrations were greater on termitaria than off termitaria, with approximately twice the concentration of these nutrients. Browse preference followed the between-site differences in soil and foliar nutrient concentrations, with higher selection ratios and bite intensities for vegetation on termitaria than off termitaria. Diospyros quiloensis was the most preferred browse species whilst Combretum imberbe, Kigelia africana and Strychnos innocua were the least. In conclusion, the black rhino preferred vegetation on termitaria to that in the surrounding matrix, and utilization of vegetation can be influenced by the soil substrate on which tree species grow.

Complex ecological associations: competition and facilitation in a sponge–algal interaction

Over the past few decades, Caribbean coral reefs have undergone a phase shift from coral-dominated to algal-dominated communities due to several factors, including increased input of anthropogenic nutrients. With the decline in coral cover, sponges have also become more dom- inant members of Caribbean coral reef communities. Increased algal and sponge dominance on Caribbean reefs has led to an increase in the frequency of interaction between these 2 groups. This study used a factorial design to assess the independent and interactive effects of contact and elevated nutrient levels on 2 common members of these communities, the sponge Aplysina cauli- formis, and the macroalga Microdictyon marinum. Algal contact had a significant negative phys- iological effect on A. cauliformis, affecting both the host sponge and its cyanobacterial symbionts. While elevated nutrient levels had some positive effects on the sponge photosymbionts, this only occurred in the absence of algal contact or a shading/abrasion control, and elevated nutrient lev- els had a negative effect on the sponge holobiont. In contrast, M. marinum responded positively to experimentally enhanced nutrient levels and to sponge contact under ambient nutrient regimes, but was not affected by sponge contact under elevated nutrient concentrations. Stable isotope enrichment experiments showed that the alga's positive response to sponge contact was associated with nitrogen transfer from the sponge over the course of the experiment. Thus, while A. cauliformis facilitates increased productivity in M. marinum, algal contact competitively inhibits sponge condition.

Nutria Grazing Preference as a Function of Fertilization

In Louisiana, subsiding wetlands frequently receive diverted fresh river water, which contains nutrients, stimulates vegetative growth, and may increase vertical accretion via vegetative growth. When river water is introduced, varying nutrient and salinity concentrations are produced. These varying conditions within marshes probably influence the feeding habits of herbivorous animals because of a preference for vegetation high in nutrients and low in salinity. Nutria (Myocastor coypus), a large introduced rodent, can negatively affect wetlands. We speculate that, driven by a biological need for nitrogen, nutria may affect treated wetlands more than untreated wetlands. Therefore, we sought to determine if wild-captured nutria preferred fertilized versus unfertilized plants of the following species: Panicum hemitomon Schult., Sagittaria lancifolia L., and Spartina patens (Aiton) Muhl. Nutria showed a significant preference for fertilized over non-fertilized samples, potentially caused by nutrient-driven increases in the nitrogen concentrations of fertilized plants, changes in the carbon to nitrogen ratio within plant tissue, and the universal animal need for biologically available nutrients to maintain homeostasis. Preliminary findings may partially explain observations of reduced plant abundance where elevated levels of nutrients are introduced to nutrient-limited wetlands, possibly necessitating a re-examination of proposed diversion implications and focusing nutria control efforts in such places.

Responses of the invasive aquatic plant water hyacinth to altered nutrient levels under experimental warming in China

Global warming and eutrophication may interact and increase the invasiveness of certain aquatic plants. To test this hypothesis, a mesocosm experiment was conducted to investigate the growth, biomass allocation and carbon/nitrogen balance of the invasive aquatic plant Eichhornia crassipes (Mart.) Solms in response to three nutrient levels representing oligotrophic to eutrophic water under simulated warming in a greenhouse. The growth and clonal propagation of E. crassipes were significantly promoted by simulated warming and elevated nutrient levels. The mean relative growth rate and mean clonal propagation rate of the plants increased 32% and 152% due to elevated nutrient levels, whereas those values increased 18.3% and 14.9% due to warming. The shoot/root ratio of E. crassipes was also greatly improved by simulated warming (50.2% increase) and elevated nutrient levels (475% increase). Moreover, the leaf and stembase N concentrations increased and C/N mass ratios decreased with elevated temperature and nutrient levels. These results suggest that the ecological invasion of the highly invasive aquatic plant E. crassipes will be exacerbated by increasing eutrophication under future climate warming in China.

Nearshore benthic blooms of filamentous green algae in Lake Baikal

For the first time, species of the genus Spirogyra, non-typical of the open nearshore waters of Lake Baikal, formed algal mats with Ulothrix zonata, Ulothrix tenerrima, and Ulothrix tenuissima near the village of Listvyanka, Russia. Normally widely distributed in the 0- to 1.5-m depth range, the growth of U. zonata was now evident and dominant (63% of the biomass) in the 2- to 5-m depth range. The overgrowth of the lake bottom by filamentous green algae, changes in distributional boundaries, the emergence and mass development of species of the genus Spirogyra, the presence of the eutrophic diatom indicator Fragilaria capucina var. vaucheriae, elevated abundances of coliform bacteria, and elevated levels of nutrients suggest an early stage of cultural eutrophication in the nearshore of Lake Baikal near Listvyanka, a popular tourist destination. The unusual abundance of Fragilaria associated with the filamentous green algae consisted of long-ribbon colonies of F. capucina var. vaucheriae, a eutrophic species, wound around the filamentous green algae, enhancing the dense algae mats. Historically dominant species, such as Didymosphenia geminata, Tetraspora cylindrica var. bullosa, and Draparnaldioides baicalensis typically observed at deeper depths of Lake Baikal, are now subdominants or minor species in the nearshore along the shoreline near Listvyanka.

Nutritional Significance of the Edible Insect,Hemijana variegataRothschild (Lepidoptera: Eupterotidae), of the Blouberg Region, Limpopo, South Africa

Hemijana variegata Rothschild, an edible caterpillar of Limpopo, South Africa, is little known to science but is a delicacy in the region. Harvesters believe the caterpillar is nourishing but there are no data on its nutritional value. This study reports on the proximate nutrient analysis of sun-dried (traditionally prepared) specimens and specimens oven-dried at 60 °C for three different time periods (24, 48 and 72 h). For the vitamin content analysis, fresh caterpillars were used. Drying at 60 °C for 24 h produced the highest energy value at 552 kcal/100 g while traditionally prepared caterpillars produce 306 kcal/100 g. The caterpillar was found to be rich in protein varying between 51 and 54 % for oven-dried and 44.5 % for traditionally prepared caterpillars. The fat content of 20 % is favourable, as is the percentage ash (10.47 % for traditionally prepared caterpillars), indicating elevated levels of nutrients. In fresh caterpillars, vitamin content was low for vitamin A (0.02 mg/100 g) and vitamin B...

Fine-scale nutrient enrichment and water quality on the rural shores of Southeast Lake Huron

Recently, there has been public concern that water quality in the nearshore of Southeast Lake Huron has been deteriorating, inferred partly from fouling of shoreline by algae. In 2010, fine-scale patterns in nutrient concentrations and other water quality features were examined to better understand the influence of the adjacent land on the nearshore environment in the region. Surveys at two areas of coastline were conducted over a seasonal cycle. Monitoring of water quality in tributaries to the study areas indicated that water of poor quality was periodically discharged to the lake as indicated by elevated levels of nutrients, fecal indicator bacteria, suspended solids and chloride. The extent of the nearshore that was directly influenced by land runoff was small, restricted to the shoreline fringe, relative to the broader nearshore. Pulse-like inputs of phosphorus from wave-induced erosional events and periods of precipitation-related runoff, both characterized by high levels of particle-bound phosphorus, contributed to highly dynamic and spatially variable levels of total phosphorus (TP), and proportions of TP in dissolved form, in the nearshore. The proportion of TP associated with particulate material was strongly correlated with lake depth. Phosphorus distributions in the nearshore indicate contrasting conditions with proximity to shoreline. Land runoff enriches nutrient levels along sections of the immediate shoreline, which contrasts sharply with the ultraoligotrophic conditions in the broader nearshore. The nearshore of Lake Huron arguably has always been highly sensitive to phosphorus pollution and it appears likely that the shoreline may be even more so today.

Implications of applied best management practice for peatland forest harvesting

Elevated levels of nutrients and suspended sediment (SS), and changes to other environmental parameters, are frequently associated with forestry harvesting (clearfelling) operations, and are indicative of the potentially complex changing environment associated with clearfelling. Current and future recommended best management practices (BMPs) for forestry clearfelling on upland peat catchments must provide for a healthy soil and good water quality. The aim of this study was to quantify the effects of implementation, or violation, of BMPs in the clearfelling of an upland peat conifer forest. Over periods of 12 months prior to clearfelling and 15 months after clearfelling, two peatland forests, comprising a study control (no clearfelling) and a study site (clearfelling), were monitored for the release of phosphorus (P) and nitrogen (N) species (dissolved reactive phosphorus (DRP), total phosphorus (TP), total oxidised nitrogen (TON) and ammonium nitrogen (NH4+-N)), SS, dissolved oxygen (DO), electrical conductivity (EC), pH and stream water temperature. Clearfelling was conducted during poor weather conditions and a watercourse, which drained the study site, was not protected. The maximum recorded concentration exported from the study site after clearfelling was 471μgL−1 for DRP, 611μgL−1 for TP, 1336μgL−1 for NH4+-N, and 194μgL−1 for TON. Concentrations of SS exiting the study site increased in one of the two samples taken during clearfelling (maximum release of 481mgL−1, with 68% of this organic) and returned to pre-clearfelling levels, or below, within 6 months of the commencement of clearfelling. Exports of TP and DRP from the study site were 0.9 and 0.4kgha−1yr−1, which were greater than the study control (0.6 and 0.2kgha−1yr−1, respectively). This indicated that the mitigation practices employed on site were not effective in phosphorus retention.

Is there a role for the adaptive immune system in pancreatic beta cell failure in type 2 diabetes?

Pancreatic beta cell failure dictates the clinical onset of type 2 diabetes, with insulin secretion insufficient to overcome peripheral tissue insulin resistance. Over the past 5-10 years, a convincing case has emerged supporting the contribution of islet inflammation to this beta cell failure. IL-1 is central to this insult, impairing insulin secretion in preclinical and clinical studies. Further, islet-infiltrating macrophages are a major source of IL-1 and other cytokines in response to elevated levels of nutrients (glucose, saturated fatty acids), endocannabinoids and islet amyloid polypeptide (IAPP). In this issue of Diabetologia, Butcher et al have further characterised immune cell subsets present in islets from individuals with type 2 diabetes (DOI: 10.1007/s00125-013-3116-5). Increased numbers of CD45(+) leucocytes were found in these islets compared with islets from healthy controls, with an elevated proportion of CD20(+) B cells within the CD45(+) population. Their data also suggest that absolute numbers of CD3(+) T cells and CD11b(+)CD11c(+) myeloid cells may be increased in islets from individuals with type 2 diabetes. While many aspects of islet inflammation await further exploration, the study from Butcher and colleagues suggests a role for immune cell-mediated inflammation early in disease pathogenesis, and supports the concept that targeting the immune system may slow continued beta cell demise in type 2 diabetes.