Search

The goal of the DISCOVR consortium is to improve the annualized areal production of open algal production systems through a process of algal strain evaluation and selection combined with testing in outdoor pilot scale production systems. The role of Sandia National Laboratories, in this evaluation process, has been to screen the selected subset of algal strains for resistance to grazing. Sandia tested 9 marine and 8 freshwater strains of algae against a panel of 14 grazer species, (5 marine, 5 freshwater and 4 euryhaline). A total of 153 algal/grazer pairs at two grazer concentrations for a total of 306 assays in triplicate. The relative resistance of each algal strain to each grazer strain was expressed as the decimal fraction of its specific growth rate 29in the presence of the grazer divided by the growth rate of the algae alone. Of the strains tested, those with the greatest resistance to the grazer panel were the freshwater strains Acutodesmus obliquus UTEX 393 and Scenedesmus obliquus. DOE 152z, and the marine strains Micractinium sp 14-F2 and Scenedesmus sp. 46B-D3. Additionally, these assays revealed the unexpected levels of variation in grazer resistance between taxonomically related organisms. • Large variation exists in algal resistance to grazing. • Resistance to a given grazer species is not indicative to resistance to a similar species. • Taxonomically related strains can demonstrate different patterns of grazer resistance. [ABSTRACT FROM AUTHOR]

Abstract: Large-scale cultivation of microalgae for biofuels may avoid competing for agriculture, water, and fertilizer by using wastewater and avoid competing for land by using the Offshore Membrane Enclosures for Growing Algae (OMEGA) system. Some microalgae thrive in wastewater; however, wastewater also contains a complex mixture of organisms. An algae culture in wastewater from a San Francisco Treatment Facility in a 1600-L OMEGA culture system was monitored by standard methods. Prima facie evidence of a chytrid infection prompted a detailed investigation of the microbiome over a 13-day period using second generation sequencing of hypervariable regions of the small subunit rRNA genes. The observed bacteria, initially dominated by γ-proteobacteria, shifted to Cytophagia, Flavobacteriia, and Sphingobacteriia after addition of exogenous nutrients. The dominant algae genera introduced with the inoculum, Desmodesmus and Scenedesmus, remained over 70% of the sequence reads on day 13, although the optical density and fluorescence of the culture declined. Nonalgal eukarya, initially dominated by unclassified alveolates, chrysophytes, and heliozoan grazers, shifted to chytrid fungi on day 5 and continued to day 13. The results of this microbiome analysis can facilitate the development of probe or primer based surveillance systems for routine monitoring of large-scale microalgae cultures. [Copyright &y& Elsevier]

The meteorological conditions are investigated over the state of Victoria, Australia on 7 February 2009, the day of the 'Black Saturday' fires. Daytime temperatures exceeding 45°C, strong surface winds and extremely dry conditions combined to produce the worst fire weather conditions on record. A high-resolution nested simulation with the UK Met Office Unified Model and available observations are used to identify the important mesoscale features of the day. The highest resolution domain has horizontal grid spacing of 444 m and reproduces most aspects of the observed meteorological conditions. These include organized horizontal convective rolls, a strong late-afternoon cool change with many of the characteristics of an unsteady gravity current, a weaker late-evening cold front and propagating nocturnal bores. These mesoscale phenomena introduce variability in the winds, temperature and humidity at short temporal and spatial scales, which in turn lead to large spatial and temporal variability in fire danger. Copyright © 2012 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

Grazing and parasitism in algal production systems are significant causes of crop loss. Biological control of algal ponds, such as application of protective bacteria, represents a promising alternative to current mitigation strategies. The major barriers to probiotic methods are the lack of identified protective bacteria and uncertainty of scale-up effects, including potential negative interactions with the resident algal microbiome. Here, we report that application of Janthinobacter lividum affords robust protection against rotifer (Brachionus plicatilis) grazing on Microchloropsis salina. Protection was observed at laboratory scale from live bacteria and solvent extract additions as well as in biologically complex communities from bacterial additions to outdoor mesocosms. J. lividum persisted in outdoor communities for at least 3 days following addition, and did not lead to selective exclusion of specific taxa in the resident microbiome. These results demonstrate that J. lividum can provide protection against grazers in these diverse communities, without severe effects on the resident microbiome. Our results suggest that J. lividum is a promising treatment to mitigate algal crop losses due to pests. Additionally, the study highlights the importance of an ecologically-informed approach to algal crop management that will aid future applications in the biological control of algal ponds. • Bacterial addition reduces algal grazing without negatively affecting algal growth. • Bacterial extracts reduce grazing and algal growth, implicating bacterial toxins. • Outdoor bacterial additions do not reduce yield, nor displace microbiome taxa. • Bacterial control of grazers may be a promising tool for algal crop protection. [ABSTRACT FROM AUTHOR]

Investigates the characteristics of gravity waves induced by mesoscale convective storms and the gravity wave sources using a two-dimensional cloud-resolving numerical model. Similarity of vertical wavelengths; Magnitudes of gravity waves in the quasi-linear dry simulations comparable with each other in spite of the differences in the magnitude of the nonlinear and diabatic sources.

To address challenges in early detection of pond pests, we have extended a spectroradiometric monitoring method, initially demonstrated for measurement of pigment optical activity and biomass, to the detection of algal competitors and grazers. The method relies upon measurement and interpretation of pond reflectance spectra spanning from the visible into the near-infrared. Reflectance spectra are acquired every 5 min with a multi-channel, fiber-coupled spectroradiometer, providing monitoring of algal pond conditions with high temporal frequency. The spectra are interpreted via numerical inversion of a reflectance model, in which the above-water reflectance is expressed in terms of the absorption and backscatter coefficients of the cultured species, with additional terms accounting for the pigment fluorescence features and for the water-surface reflection of sunlight and skylight. With this method we demonstrate detection of diatoms and the predator Poteriochromonas in outdoor cultures of Nannochloropsis oceanica and Chlorella vulgaris , respectively. The relative strength of these signatures is compared to microscopy and sequencing analysis. Spectroradiometric detection of diatoms is then further assessed on beaker-contained mixtures of Microchloropsis salina with Phaeodactylum tricornutum, Thalassiosira weissflogii , and Thalassiosira pseudonana , respectively, providing an initial evaluation of the sensitivity and specificity of detecting pond competitors. • Spectroradiometric monitoring has been extended to the detection of algal competitors and grazers • Demonstrate early detection of a diatom invasion and the predator Poteriochromonas in outdoor algal cultures • Results are compared to microscopy and sequencing analysis • Approach could be extended to drone-based deployment for application to large-scale algal farming [ABSTRACT FROM AUTHOR]

Algal biomass is a proposed feedstock for sustainable production of petroleum displacing commodities. However, production of 10% of US demand for liquid transportation fuel from algae would require a 60–150% increase over current agricultural demand for phosphorus fertilizers. Without efforts to recycle major nutrients, algal biomass production can be expected to catalyze a food versus fuel crisis. We have developed a novel and simple process for efficient liberation of phosphate from algal biomass and have demonstrated recycling at both laboratory and pilot scale, of up to 70% of total cellular phosphate from osmotically-shocked but non-denatured Microchloropsis salina biomass using a range of mild incubation conditions. The phosphate released in this process is bioavailable, can support the same level of algal growth as standard nutrients, and does not contain any growth inhibitory compounds as evidenced by its ability to support multiple sequential cycles of growth and remineralization. • Short incubation of native disrupted algal biomass will release cellular phosphate. • Released soluble phosphate will support algal growth. • There is no evidence of the presence of algal growth inhibitors in recycled phosphate. [ABSTRACT FROM AUTHOR]

Open algal ponds are likely to succumb to unpredictable, devastating crashes by one or several deleterious species. Developing methodology to mitigate or prevent pond crashes will increase algal biomass production, drive down costs for algae farmers, and reduce the risk involved with algae cultivation, making it more favorable for investment by entrepreneurs and biotechnology companies. Here, we show that specific algal-bacterial co-cultures grown with the green alga Microchloropsis salina prevented grazing by the marine rotifer, Brachionus plicatilis. We obtained seven algal-bacterial co-cultures from crashed rotifer cultures, maintained them in co-culture with Microchloropsis salina , and used a microalgal survival assay to determine that algae present in each co-culture were protected from rotifer grazing and culture crash. After months of routinely diluting and maintaining these seven algal-bacterial co-cultures, we repeated the assay and found the opposite result: none of the seven bacterial communities protected the microalgae from rotifer grazing. We performed 16S rRNA gene amplicon sequencing on the protective and nonprotective co-culture samples and identified substantial differences in the makeup of the bacterial communities. Protective bacterial communities consisted primarily of Alphaproteobacteria (Rhodobacteraceae) and Gammaproteobacteria (Marinobacter , Pseudomonas , Methylophaga) while nonprotective bacterial communities were less diverse and missing many putatively crucial members. We compared the seven protective communities with the seven nonprotective communities and we correlated specific bacterial amplicon sequence variants with algal protection. With these data, our future work will aim to define and develop an engineered-microbiome that can stabilize industrial Microchloropsis salina cultures by protecting against grazer-induced pond crashes. Unlabelled Image • Unpredictable pond crashes limit the economic feasibility of microalgal biofuel. • Seven bacterial communities are shown to protect microalgae from rotifer grazing. • We conducted community profiling to compare protective and nonprotective cultures. • Bacterial taxa putatively responsible for protective function were identified. • Algal cultivation may benefit from protective microbes that mitigate pond crashes. [ABSTRACT FROM AUTHOR]

Microalgae have major functions in global biogeochemical cycles and are promising sources of renewable energy, yet the relationships between algal hosts and their associated microbiomes remain relatively underexplored. Understanding community organization of microalgal microbiomes, such as how algal species identity influences bacterial community structure, will aid in efforts to engineer more efficient phototrophic ecosystems. Here, we examined the community assembly of phycosphere-associated (attached) and free-living bacterial taxa associated with two marine microalgae: the diatom Phaeodactylum tricornutum and eustigmatophyte Microchloropsis salina. Samples were collected from outdoor mesocosms, raceway ponds, and laboratory enrichments, and bacterial taxa identified by 16S rRNA gene sequences. In outdoor mesocosms, we found distinct bacterial taxa associated with each algal species, including the Cytophagaceae and Rhodobacteraceae families with P. tricornutum , and Rhodobacteraceae, Hyphomonadaceae, and Saprospiraceae with M. salina. Additionally, there were host-specific differences in the bacterial genera associated with the phycosphere, including Novosphingobium and Rhodopirellula with P. tricornutum , and Methylophaga and Dyadobacter with M. salina. Bacterial communities from outdoor monoalgal P. tricornutum and polyalgal P. tricornutum / M. salina samples were used as inocula for laboratory enrichments with axenic P. tricornutum. Here, similar bacterial communities emerged, suggesting that the algal host exerts substantial influence over bacterial community assembly. Further enrichments for phycosphere-association revealed differing outcomes of community assembly processes contingent on the initial community composition. Phycosphere-associated communities from monoalgal P. tricornutum mesocosms were highly similar to one another, suggesting deterministic processes, whereas cultures from mixed M. salina / P. tricornutum raceways followed two apparent paths differentiated by the stochastic loss of specific community members and convergence towards or further deviation from the monoalgal samples. These results demonstrate that algal-associated bacterial communities are controlled by algal host, culture conditions, and the initial inoculum composition of the algal microbiome, and this knowledge can inform the engineering of more productive algal systems. • Microalgae influence bacterial community compositions. • Different microalgae select for different phycosphere-associated bacteria. • Stochastic events can lead to multiple stable community compositions. [ABSTRACT FROM AUTHOR]

Extended warning of above‐average and extreme precipitation is valuable to a wide range of stakeholders. However, the sporadic nature of precipitation makes it difficult to forecast skilfully beyond one week. Subseasonal forecasting is a growing area of science that aims to predict average weather conditions multiple weeks in advance using dynamical models. Building on recent work in this area, we test the hypothesis that using large‐scale horizontal moisture transport as a predictor for precipitation may increase the forecast skill of the above‐median and high‐precipitation weeks on subseasonal time‐scales. We analysed retrospective forecast (hindcast) sets from the Australian Bureau of Meteorology's latest operational subseasonal‐to‐seasonal forecasting model, ACCESS‐S2, to compare the forecast skill of precipitation using integrated water vapour transport (IVT) as a proxy, compared to using precipitation forecasts directly. We show that ACCESS‐S2 precipitation generally produces more skilful forecasts, except over some regions where IVT could be a useful additional diagnostic for warning of heavy precipitation events. [ABSTRACT FROM AUTHOR]

This study focuses on future seasonal changes in daily precipitation using Regional Climate Models (RCMs) from the Coordinated Regional Climate Downscaling Experiments-Southeast Asia ensemble (CORDEX-SEA). Projections using this RCM ensemble generally show a larger inter-model spread in winter than in summer, with higher significance and model agreement in summer over most land areas. We evaluate how well the RCMs simulate climatological precipitation using two skill metrics. To extract reliable projections, two sub-ensembles of 'better' and 'worse' performing models are selected and their respective projections compared. We find projected intensification of summer precipitation over northern SEA, which is robust across RCMs. On the contrary, in the southern part of SEA, the 'worse' ensemble projects a significant and widespread decrease in summer rainfall intensity whereas a slight intensification is projected by the 'better' ensemble. Further exploration of inter-model differences in future changes reveals that these are mainly explained by changes in moisture supply from large-scale sources (i.e., moisture convergence) with enhanced effects from local sources (i.e., evapotranspiration). The 'worse' models project greater changes in atmospheric circulation compared with the 'better' models, which can explain part of the uncertainty in projections for daily precipitation over the CORDEX-SEA domain. Hence, our findings might help assess more reliable projections over the SEA region by selecting models based on a two-step model evaluation: the ability of models to simulate historical daily precipitation and their performance in reproducing key physical processes of the regional climate. [ABSTRACT FROM AUTHOR]