Aguilar, C, Raina, JB, Fôret, S, Hayward, DC, Lapeyre, B, Bourne, DG & Miller, DJ 2019, 'Transcriptomic analysis reveals protein homeostasis breakdown in the coral Acropora millepora during hypo-saline stress', BMC Genomics, vol. 20, no. 1.
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© 2019 The Author(s). Background: Coral reefs can experience salinity fluctuations due to rainfall and runoff; these events can have major impacts on the corals and lead to bleaching and mortality. On the Great Barrier Reef (GBR), low salinity events, which occur during summer seasons and can involve salinity dropping ~ 10 PSU correlate with declines in coral cover, and these events are predicted to increase in frequency and severity under future climate change scenarios. In other marine invertebrates, exposure to low salinity causes increased expression of genes involved in proteolysis, responses to oxidative stress, and membrane transport, but the effects that changes in salinity have on corals have so far received only limited attention. To better understand the coral response to hypo-osmotic stress, here we investigated the transcriptomic response of the coral Acropora millepora in both adult and juvenile life stages to acute (1 h) and more prolonged (24 h) exposure to low salinity. Results: Differential gene expression analysis revealed the involvement of both common and specific response mechanisms in Acropora. The general response to environmental stressors included up-regulation of genes involved in the mitigation of macromolecular and oxidative damage, while up-regulation of genes involved in amino acid metabolism and transport represent specific responses to salinity stress. Conclusions: This study is the first comprehensive transcriptomic analysis of the coral response to low salinity stress and provides important insights into the likely consequences of heavy rainfall and runoff events on coral reefs.
Albert, LP, Restrepo-Coupe, N, Smith, MN, Wu, J, Chavana-Bryant, C, Prohaska, N, Taylor, TC, Martins, GA, Ciais, P, Mao, J, Arain, MA, Li, W, Shi, X, Ricciuto, DM, Huxman, TE, McMahon, SM & Saleska, SR 2019, 'Cryptic phenology in plants: Case studies, implications, and recommendations.', Global change biology.
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Plant phenology-the timing of cyclic or recurrent biological events in plants-offers insight into the ecology, evolution, and seasonality of plant-mediated ecosystem processes. Traditionally studied phenologies are readily apparent, such as flowering events, germination timing, and season-initiating budbreak. However, a broad range of phenologies that are fundamental to the ecology and evolution of plants, and to global biogeochemical cycles and climate change predictions, have been neglected because they are "cryptic"-that is, hidden from view (e.g., root production) or difficult to distinguish and interpret based on common measurements at typical scales of examination (e.g., leaf turnover in evergreen forests). We illustrate how capturing cryptic phenology can advance scientific understanding with two case studies: wood phenology in a deciduous forest of the northeastern USA and leaf phenology in tropical evergreen forests of Amazonia. Drawing on these case studies and other literature, we argue that conceptualizing and characterizing cryptic plant phenology is needed for understanding and accurate prediction at many scales from organisms to ecosystems. We recommend avenues of empirical and modeling research to accelerate discovery of cryptic phenological patterns, to understand their causes and consequences, and to represent these processes in terrestrial biosphere models.
Andersson, AJ, Venn, AA, Pendleton, L, Brathwaite, A, Camp, EF, Cooley, S, Gledhill, D, Koch, M, Maliki, S & Manfrino, C 2019, 'Ecological and socioeconomic strategies to sustain Caribbean coral reefs in a high-CO2 world', Regional Studies in Marine Science, vol. 29.
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© 2019 The Authors The Caribbean and Western Atlantic region hosts one of the world's most diverse geopolitical regions and a unique marine biota distinct from tropical seas in the Pacific and Indian Oceans. While this region varies in human population density, GDP and wealth, coral reefs, and their associated ecosystem services, are central to people's livelihoods. Unfortunately, the region's reefs have experienced extensive degradation over the last several decades. This degradation has been attributed to a combination of disease, overfishing, and multiple pressures from other human activities. Furthermore, the Caribbean region has experienced rapid ocean warming and acidification as a result of climate change that will continue and accelerate throughout the 21st century. It is evident that these changes will pose increasing threats to Caribbean reefs unless imminent actions are taken at the local, regional and global scale. Active management is required to sustain Caribbean reefs and increase their resilience to recover from acute stress events. Here, we propose local and regional solutions to halt and reverse Caribbean coral reef degradation under ongoing ocean warming and acidification. Because the Caribbean has already experienced high coral reef degradation, we suggest that this region may be suitable for more aggressive interventions that might not be suitable for other regions. Solutions with direct ecological benefits highlighted here build on existing knowledge of factors that can contribute to reef restoration and increased resilience in the Caribbean: (1)management of water quality, (2)reduction of unsustainable fishing practices, (3)application of ecological engineering, and (4)implementing marine spatial planning. Complementary socioeconomic and governance solutions include: (1)increasing communication and leveraging resources through the establishment of a regional reef secretariat, (2)incorporating reef health and sustainability goals into the bl...
Armbrecht, LH, Coolen, MJL, Lejzerowicz, F, George, SC, Negandhi, K, Suzuki, Y, Young, J, Foster, NR, Armand, LK, Cooper, A, Ostrowski, M, Focardi, A, Stat, M, Moreau, JW & Weyrich, LS 2019, 'Ancient DNA from marine sediments: Precautions and considerations for seafloor coring, sample handling and data generation', Earth-Science Reviews, vol. 196.
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Barraza, V, Alfredo Huete, Dara Entekhabi, Esteban Roitberg, Francisco Grings, María Gassmann, Mariano Franco, Natalia Restrepo-Coupe & Vanesa Douna 2019, 'Estimation of latent heat flux using satellite land surface temperature and a variational data assimilation scheme over a eucalypt forest savanna in Northern Australia', Agricultural and forest meteorology., vol. 268, pp. 341-353.
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In this study, the performance of the combined-source variational data assimilation scheme (CS-VDA) is assessed in detail using in situ heat fluxes (i.e. sensible heat (H) and latent heat (LE)) collected at a Eucalypt forest savanna of Northern Australia (Howard Springs). The CS VDA scheme estimates surface turbulent heat fluxes via assimilation of sequences of land surface temperature (LST) and meteorological data into a surface energy balance model and a dynamic model. The main objectives of this paper were to extend previous studies to a semi-arid ecosystem and to evaluate the potential of using global meteorological forcing data (GMD) to drive the CS VDA model (rather than in-situ meteorological observations). In order to study the new errors associated with the use of GMD, the effects on LE of the uncertainty in air temperature and wind speed (the two key meteorological factors that controls the total estimation error) was quantitatively characterized. Using hourly in-situ measurements as inputs, the daily-averaged LE RMSEdaily was 54 W/m2, which agrees with the errors previously reported in the literature. As expected, replacing local meteorological data with GMD reduces the performance of the LE estimation (GMA: RMSEdaily = 82 W/m2, GLDAS: RMSEdaily = 151 W/m2). However, LE RMSE values at 8-day temporal scale for GMA are RMSE8-days = 32 W/m2, similar to those reported in this area for other models (MODIS (MOD16A2) and Breathing Earth System Simulator (BESS)). The error propagation analysis indicate that the CS VDA model is very sensitive to uncertainties in wind speed measurements. Moreover, there are large discrepancies between in situ and GMD wind speed. These two factors combined can explain the degradation in LE estimations. In this context, our study is a first step towards the characterization of an operational daily LE estimation scheme using hourly LST observations.
Barros, FDV, Bittencourt, PRL, Brum, M, Restrepo-Coupe, N, Pereira, L, Teodoro, GS, Saleska, SR, Borma, LS, Christoffersen, BO, Penha, D, Alves, LF, Lima, AJN, Carneiro, VMC, Gentine, P, Lee, JE, Aragão, LEOC, Ivanov, V, Leal, LSM, Araujo, AC & Oliveira, RS 2019, 'Hydraulic traits explain differential responses of Amazonian forests to the 2015 El Niño-induced drought', New Phytologist, vol. 223, no. 3, pp. 1253-1266.
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© 2019 The Authors. New Phytologist © 2019 New Phytologist Trust Reducing uncertainties in the response of tropical forests to global change requires understanding how intra- and interannual climatic variability selects for different species, community functional composition and ecosystem functioning, so that the response to climatic events of differing frequency and severity can be predicted. Here we present an extensive dataset of hydraulic traits of dominant species in two tropical Amazon forests with contrasting precipitation regimes – low seasonality forest (LSF) and high seasonality forest (HSF) – and relate them to community and ecosystem response to the El Niño–Southern Oscillation (ENSO) of 2015. Hydraulic traits indicated higher drought tolerance in the HSF than in the LSF. Despite more intense drought and lower plant water potentials in HSF during the 2015-ENSO, greater xylem embolism resistance maintained similar hydraulic safety margin as in LSF. This likely explains how ecosystem-scale whole-forest canopy conductance at HSF maintained a similar response to atmospheric drought as at LSF, despite their water transport systems operating at different water potentials. Our results indicate that contrasting precipitation regimes (at seasonal and interannual time scales) select for assemblies of hydraulic traits and taxa at the community level, which may have a significant role in modulating forest drought response at ecosystem scales.
Behrendt, L, Trampe, EL, Nord, NB, Nguyen, J, Kühl, M, Lonco, D, Nyarko, A, Dhinojwala, A, Hershey, OS & Barton, H 2019, 'Life in the dark: Far-red absorbing cyanobacteria extend photic zones deep into terrestrial caves.', Environmental microbiology.
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Chlorophyll (Chl) f and d are the most recently discovered chlorophylls, enabling cyanobacteria to harvest near infrared radiation (NIR) at 700-780 nm for oxygenic photosynthesis. Little is known about the occurrence of these pigments in terrestrial habitats. Here we provide first details on spectral photon irradiance within the photic zones of four terrestrial cave systems in concert with a detailed investigation of photopigmentation, light reflectance, and microbial community composition. We frequently found Chl f and d along the photic zones of caves characterized by low-light enriched in NIR and inhabited by cyanobacteria producing NIR-absorbing pigments. Surprisingly, deeper parts of caves still contained NIR, an effect likely attributable to the reflectance of specific wavelengths by the surface materials of cave walls. We argue that the stratification of microbial communities across the photic zones of cave entrances resembles the light-driven species distributions in forests and aquatic environments. This article is protected by copyright. All rights reserved.
Bodachivskyi, I, Kuzhiumparambil, U & Williams, DBG 2019, 'A Systematic Study of Metal Triflates in Catalytic Transformations of Glucose in Water and Methanol: Identifying the Interplay of Bronsted and Lewis Acidity', CHEMSUSCHEM, vol. 12, no. 14, pp. 3263-3270.
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Bodachivskyi, I, Kuzhiumparambil, U & Williams, DBG 2019, 'A Systematic Study of Metal Triflates in Catalytic Transformations of Glucose in Water and Methanol: Identifying the Interplay of Brønsted and Lewis Acidity', ChemSusChem, vol. 12, pp. 3208-3208.
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© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Invited for this month′s cover is the group of Prof. Bradley Williams at the University of Technology Sydney. The image depicts the manifold products that can be selected in transformations of glucose through manipulation of the Brønsted or Lewis acidity of the catalyst. The Full Paper itself is available at 10.1002/cssc.201900292.
Bodachivskyi, I, Kuzhiumparambil, U & Williams, DBG 2019, 'Acid-Catalysed Conversion of Carbohydrates into Furan-Type Molecules in Zinc Chloride Hydrate', ChemPlusChem, vol. 84, no. 4, pp. 352-357.
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© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Acid-catalysed conversion of biomass, specifically cellulose, holds promise to create value-added, renewable replacements for many petrochemical products. We investigated an unusual acid-catalysed transformation of cellulose and cellobiose in the biphasic solvent system zinc chloride hydrate (ionic liquid)/anisole. Here, furyl hydroxymethyl ketone and furfural are obtained as major products, which are valuable but less commonly formed in high yields in transformations of cellulosic substrates. We explored this chemistry in small-scale model reactions and applied the optimised methods to the conversion of cellulose in bench-scale processes. The optimum reaction system and preferred reaction conditions are defined to select for highly desirable furanoid products in the highest known yields (up to 46 %) directly from cellulose or cellobiose. The method avoids the use of added catalysts: the ionic solvent zinc chloride hydrate possesses the intrinsic acidity required for the hydrolysis and chemical transformation steps. The process involves inexpensive media for the catalytic conversion of cellulose into high-value products under mild processing conditions.
Bramucci, AR & Case, RJ 2019, 'Phaeobacter inhibens induces apoptosis-like programmed cell death in calcifying Emiliania huxleyi', Scientific Reports, vol. 9, no. 1.
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© 2019, The Author(s). The model coccolithophore, Emiliania huxleyi, forms expansive blooms dominated by the calcifying cell type, which produce calcite scales called coccoliths. Blooms last several weeks, after which the calcified algal cells rapidly die, descending into the deep ocean. E. huxleyi bloom collapse is attributed to E. huxleyi viruses (EhVs) that infect and kill calcifying cells, while other E. huxleyi pathogens, such as bacteria belonging to the roseobacter clade, are overlooked. EhVs kill calcifying E. huxleyi by inducing production of bioactive viral-glycosphingolipids (vGSLs), which trigger algal programmed cell death (PCD). The roseobacter Phaeobacter inhibens was recently shown to interact with and kill the calcifying cell type of E. huxleyi, but the mechanism of algal death remains unelucidated. Here we demonstrate that P. inhibens kills calcifying E. huxleyi by inducing a highly specific type of PCD called apoptosis-like-PCD (AL-PCD). Host death can successfully be abolished in the presence of a pan-caspase inhibitor, which prevents the activation of caspase-like molecules. This finding differentiates P. inhibens and EhV pathogenesis of E. huxleyi, by demonstrating that bacterial-induced AL-PCD requires active caspase-like molecules, while the viral pathogen does not. This is the first demonstration of a bacterium inducing AL-PCD in an algal host as a killing mechanism.
Bretherton, L, Poulton, AJ, Lawson, T, Rukminasari, N, Balestreri, C, Schroeder, D, Mark Moore, C & Suggett, DJ 2019, 'Day length as a key factor moderating the response of coccolithophore growth to elevated pCO 2', Limnology and Oceanography, vol. 64, no. 3, pp. 1284-1296.
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© 2019 The Authors. Limnology and Oceanography published by Wiley Periodicals, Inc. on behalf of Association for the Sciences of Limnology and Oceanography. The fate of coccolithophores in the future oceans remains uncertain, in part due to key factors having not been standardized across experiments. A potentially moderating role for differences in day length (photoperiod) remains largely unexplored. We therefore cultured four different geographical isolates of the species Emiliania huxleyi, as well as two additional species, Gephyrocapsa oceanica (tropical) and Coccolithus braarudii (temperate), to test for interactive effects of pCO 2 with the light : dark (L : D) cycle. We confirmed a general regulatory effect of photoperiod on the pCO 2 response, whereby growth and particulate inorganic carbon and particulate organic carbon (PIC : POC) ratios were reduced with elevated pCO 2 under 14 : 10 h L : D, but these reductions were dampened under continuous (24 h) light. The dynamics underpinning this pattern generally differed for the temperate vs. tropical isolates. Reductions in PIC : POC with elevated pCO 2 for tropical taxa were largely through reduced calcification and enhanced photosynthesis under 14 : 10 h L : D, with differences dampened under continuous light. In contrast, reduced PIC : POC for temperate strains reflected increases of photosynthesis that outpaced increases in calcification rates under 14 : 10 h L : D, with both responses again dampened under continuous light. A multivariate analysis of 35 past studies of E. huxleyi further demonstrated that differences in photoperiod account for as much as 40% (strain B11/92) to 55% (strain NZEH) of the variance in reported pCO 2 -induced reductions to growth but not PIC : POC. Our study thus highlights a critical role for day length in moderating the effect of ocean acidification on coccolithophore growth and consequently how this response may play out across latitudes and seasons in future oceans.
Brodersen, KE, Koren, K, Revsbech, NP & Kühl, M 2019, 'Strong leaf surface basification and CO2 limitation of seagrass induced by epiphytic biofilm microenvironments.', Plant, cell & environment.
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Coastal eutrophication is a growing problem worldwide, leading to increased epiphyte overgrowth of seagrass leaves. Yet, little is known about how epiphytes affect key biogeochemical conditions and processes in the seagrass phyllosphere. We used electrochemical microsensors to measure microgradients of O2 , pH, and CO2 at the bare and epiphyte-covered leaf surface of seagrass (Zostera marina L.) to determine effects of epiphytes on the leaf chemical microenvironment. Epiphytes result in extreme daily fluctuations in pH, O2 and inorganic carbon concentrations at the seagrass leaf surface severely hampering the plant's performance. In light, leaf epiphyte biofilms and their diffusive boundary layer (DBL) lead to strong basification, markedly reducing the CO2 and HCO3 - availability at the leaf surface, leading to reduced photosynthetic efficiency as a result of carbon limitation and enhanced photorespiration. With epiphytes, leaf surface pH increased to >10, thereby exceeding final pH levels (~9.62) and CO2 compensation points for active photosynthesis. In darkness, epiphyte biofilms resulted in increased CO2 and hypoxia at the leaf surface. Epiphytes can lead to severe carbon limitation in seagrasses owing to strong phyllosphere basification leading to CO2 depletion and costly, yet limiting, HCO3 - utilization, increasing the risk of plant starvation.
Buapet, P, Mohammadi, NS, Pernice, M, Kumar, M, Kuzhiumparambil, U & Ralph, PJ 2019, 'Excess copper promotes photoinhibition and modulates the expression of antioxidant-related genes in Zostera muelleri', AQUATIC TOXICOLOGY, vol. 207, pp. 91-100.
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Canonico, G, Buttigieg, PL, Montes, E, Muller-Karger, FE, Stepien, C, Wright, D, Benson, A, Helmuth, B, Costello, M, Sousa-Pinto, I, Saeedi, H, Newton, J, Appeltans, W, Bednaršek, N, Bodrossy, L, Best, BD, Brandt, A, Goodwin, KD, Iken, K, Marques, AC, Miloslavich, P, Ostrowski, M, Turner, W, Achterberg, EP, Barry, T, Defeo, O, Bigatti, G, Henry, LA, Ramiro-Sánchez, B, Durán, P, Morato, T, Murray Roberts, J, García-Alegre, A, Cuadrado, MS & Murton, B 2019, 'Global observational needs and resources for marine biodiversity', Frontiers in Marine Science, vol. 6, no. JUL.
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© 2019 Canonico, Buttigieg, Montes, Muller-Karger, Stepien, Wright, Benson, Helmuth, Costello, Sousa-Pinto, Saeedi, Newton, Appeltans, Bednaršek, Bodrossy, Best, Brandt, Goodwin, Iken, Marques, Miloslavich, Ostrowski, Turner, Achterberg, Barry, Defeo, Bigatti, Henry, Ramiro-Sánchez, Durán, Morato, Roberts, García-Alegre, Cuadrado and Murton. The diversity of life in the sea is critical to the health of ocean ecosystems that support living resources and therefore essential to the economic, nutritional, recreational, and health needs of billions of people. Yet there is evidence that the biodiversity of many marine habitats is being altered in response to a changing climate and human activity. Understanding this change, and forecasting where changes are likely to occur, requires monitoring of organism diversity, distribution, abundance, and health. It requires a minimum of measurements including productivity and ecosystem function, species composition, allelic diversity, and genetic expression. These observations need to be complemented with metrics of environmental change and socio-economic drivers. However, existing global ocean observing infrastructure and programs often do not explicitly consider observations of marine biodiversity and associated processes. Much effort has focused on physical, chemical and some biogeochemical measurements. Broad partnerships, shared approaches, and best practices are now being organized to implement an integrated observing system that serves information to resource managers and decision-makers, scientists and educators, from local to global scales. This integrated observing system of ocean life is now possible due to recent developments among satellite, airborne, and in situ sensors in conjunction with increases in information system capability and capacity, along with an improved understanding of marine processes represented in new physical, biogeochemical, and biological models.
Cardona, T, Sánchez-Baracaldo, P, Rutherford, AW & Larkum, AW 2019, 'Early Archean origin of Photosystem II.', Geobiology, vol. 17, no. 2, pp. 127-150.
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Photosystem II is a photochemical reaction center that catalyzes the light-driven oxidation of water to molecular oxygen. Water oxidation is the distinctive photochemical reaction that permitted the evolution of oxygenic photosynthesis and the eventual rise of eukaryotes. At what point during the history of life an ancestral photosystem evolved the capacity to oxidize water still remains unknown. Here, we study the evolution of the core reaction center proteins of Photosystem II using sequence and structural comparisons in combination with Bayesian relaxed molecular clocks. Our results indicate that a homodimeric photosystem with sufficient oxidizing power to split water had already appeared in the early Archean about a billion years before the most recent common ancestor of all described Cyanobacteria capable of oxygenic photosynthesis, and well before the diversification of some of the known groups of anoxygenic photosynthetic bacteria. Based on a structural and functional rationale, we hypothesize that this early Archean photosystem was capable of water oxidation to oxygen and had already evolved protection mechanisms against the formation of reactive oxygen species. This would place primordial forms of oxygenic photosynthesis at a very early stage in the evolutionary history of life.
Clifton, J, Osman, EO, Suggett, DJ & Smith, DJ 2019, 'Resolving conservation and development tensions in a small island state: A governance analysis of Curieuse Marine National Park, Seychelles', Marine Policy.
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© 2019 Elsevier Ltd The management and conservation of marine resources in Seychelles, a small island developing state (SIDS) in the western Indian Ocean, is fundamental to maintaining the flow of international visitors which forms the mainstay of the nation's economy. There is an increasing trend towards empowering non-governmental organisations and parastatal entities with protected area management responsibilities, which partly reflects the chronic underfunding of the state protected area management institution. This paper explores these and related issues through a governance analysis of Curieuse Marine National Park, which is the most popular state-owned marine national park in terms of recorded visitor numbers. This demonstrates that the inability to implement economic incentives through not fully capitalising on the use and non-use values of the park has deleterious consequences for managing the combined impacts of tourism and fisheries on the ecological assets of the park. Furthermore, the capacity of the state management institution is being eroded through a focus on the development of an extensive network of new marine protected areas under the direction of an international non-governmental organisation. Suggestions are made that could strengthen economic, participative and interpretative incentives to provide a more sustainable basis for marine national park management.
Coleman, MA, Clark, JS, Doblin, MA, Bishop, MJ & Kelaher, BP 2019, 'Genetic differentiation between estuarine and open coast ecotypes of a dominant ecosystem engineer', Marine and Freshwater Research.
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© CSIRO 2018. Temperate intertidal shores globally are often dominated by habitat-forming seaweeds, but our knowledge of these systems is heavily biased towards northern hemisphere species. Rocky intertidal shores throughout Australia and New Zealand are dominated by a single monotypic species, Hormosira banksii. This species plays a key role in facilitating biodiversity on both rocky shores and estuarine habitats, yet we know little about the processes that structure populations. Herein we characterise the genetic diversity and structure of Hormosira and demonstrate strong restrictions to gene flow over small spatial scales, as well as between estuarine and open coast populations. Estuarine ecotypes were often genetically unique from nearby open coast populations, possibly due to extant reduced gene flow between habitats, founder effects and coastal geomorphology. Deviations from random mating in many locations suggest complex demographic processes are at play within shores, including clonality in estuarine populations. Strong isolation by distance in Hormosira suggests that spatial management of intertidal habitats will necessitate a network of broad-scale protection. Understanding patterns of genetic diversity and gene flow in this important ecosystem engineer will enhance the ability to manage, conserve and restore this key species into the future.
Collins, S, Boyd, PW & Doblin, MA 2019, 'Evolution, Microbes, and Changing Ocean Conditions.', Annual review of marine science.
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Experimental evolution and the associated theory are underutilized in marine microbial studies; the two fields have developed largely in isolation. Here, we review evolutionary tools for addressing four key areas of ocean global change biology: linking plastic and evolutionary trait changes, the contribution of environmental variability to determining trait values, the role of multiple environmental drivers in trait change, and the fate of populations near their tolerance limits. Wherever possible, we highlight which data from marine studies could use evolutionary approaches and where marine model systems can advance our understanding of evolution. Finally, we discuss the emerging field of marine microbial experimental evolution. We propose a framework linking changes in environmental quality (defined as the cumulative effect on population growth rate) with population traits affecting evolutionary potential, in order to understand which evolutionary processes are likely to be most important across a range of locations for different types of marine microbes. Expected final online publication date for the Annual Review of Marine Science, Volume 12 is January 3, 2020. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
Commault, AS, Fabris, M, Kuzhiumparambil, U, Adriaans, J, Pernice, M & Ralph, PJ 2019, 'Methyl jasmonate treatment affects the regulation of the 2-C-methyl-D-erythritol 4-phosphate pathway and early steps of the triterpenoid biosynthesis in Chlamydomonas reinhardtii', ALGAL RESEARCH-BIOMASS BIOFUELS AND BIOPRODUCTS, vol. 39.
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Curson, ARJ, Williams, BT, Pinchbeck, BJ, Sims, LP, Martínez, AB, Rivera, PPL, Kumaresan, D, Mercadé, E, Spurgin, LG, Carrión, O, Moxon, S, Cattolico, RA, Kuzhiumparambil, U, Guagliardo, P, Clode, PL, Raina, J-B & Todd, JD 2019, 'Author Correction: DSYB catalyses the key step of dimethylsulfoniopropionate biosynthesis in many phytoplankton.', Nature microbiology, vol. 4, no. 3, pp. 540-542.
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In the version of this Letter originally published, the Methods incorrectly stated that all phytoplankton cultures were sampled in mid-exponential phase. The low-nitrogen cultures were sampled in early stationary phase and at the point at which Fv/Fm values decreased, to indicate that cultures were experiencing low-nitrogen conditions. All other phytoplankton cultures were sampled in exponential phase. Growth and Fv/Fm data are provided here on high- and low-nitrogen cultures (Figs 1, 2 and 3) to clarify and support this correction. The Methods also stated that cell counting was done using a Beckman Multisizer 3 Coulter Counter, but a CASY Model TT Cell Counter was used.
De Lima Ribeiro, A, Artlett, C, Ajani, P, Derkenne, C & Pask, H 2019, 'Impact of fluorescence on Raman remote sensing of temperature in natural water samples', Optics Express, vol. 27, no. 16, pp. 22339-22351.
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Duke, NC, Field, C, Mackenzie, JR, Meynecke, JO & Wood, AL 2019, 'Rainfall and its possible hysteresis effect on the proportional cover of tropical tidal-wetland mangroves and saltmarsh-saltpans', Marine and Freshwater Research, vol. 70, no. 8, pp. 1047-1055.
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© 2019 CSIRO. Mangrove-saltmarsh tidal wetlands are highly dynamic ecosystems, responding and adapting to climate and physical conditions at all spatial and temporal scales. Knowledge of the large-scale ecosystem processes involved and how they might be influenced by climate variables is highly relevant today. For tidal-wetland sites well within the latitudinal range of the mostly tropical mangrove communities, we confirm that average annual rainfall influences vegetative cover, as well as species composition and biomass of tidal wetlands. On the basis of 205 largely unmodified, tropical and subtropical estuaries of northern Australia, a sigmoidal relationship, with a centroid inflection point ∼1368 mm, was derived between rainfall and the relative amounts of high-biomass mangroves and low-biomass saltmarsh-saltpan vegetation. The presence and probability of observed combinations of these community types were quantified using the wetland cover index, which is the ratio of total mangrove area to that of mangroves plus intertidal saltmarsh and saltpans. Accordingly, periodic changes in rainfall trends are likely manifest as either encroachment or dieback of mangroves along the ecotones separating them from tidal saltmarsh-saltpans. Presented is a new conceptual framework and model that describes how such ecosystem-scale processes take place in tropical and subtropical tidal wetlands.
Filippini, G, Bugnot, AB, Johnston, EL, Ruszczyk, J, Potts, J, Scanes, P, Ferguson, A, Ostrowski, M, Varkey, D & Dafforn, KA 2019, 'Sediment bacterial communities associated with environmental factors in Intermittently Closed and Open Lakes and Lagoons (ICOLLs)', Science of the Total Environment, vol. 693.
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© 2019 Elsevier B.V. Intermittently Closed and Open Lakes and Lagoons (ICOLLS) are important coastal systems that are periodically separated from the ocean by a sand barrier or a berm. In urban ICOLLs, continuous inputs of organic material and nutrients into coastal lagoons are contributing to eutrophic conditions that, together with natural environmental factors have implications for the resident sediment bacterial communities. We used molecular tools to investigate the ecological communities of four ICOLLs; Narrabeen, Dee Why, Curl Curl and Manly in Sydney, Australia, which have been subjected to increasing pressure from anthropogenic activities over the last century. We used targeted gene sequencing of the prokaryotic 16S ribosomal RNA gene to describe the bacterial diversity and community structure and discuss differences with respect to environmental factors at the ICOLL scale (e.g. size, shape, normalised N loading) and site scale (e.g. water and sediment quality) within each lagoon. Due to differences in hydrological patterns, we expected that sediment bacterial communities would be more heterogenous in displacement-dominated lagoons (Curl Curl and Manly) than the mixing-dominated lagoons (Narrabeen and Dee Why). Interestingly, we did not find strong relationships between the main bacterial groups and distance from the lagoon entrance (used as a proxy for salinity and silt) in the displacement-dominated lagoons. Moreover, we found that α diversity was highest in Narrabeen and Manly lagoons despite differences in lagoon size and shape. Furthermore, while bacterial community structure was similar in Curl Curl and Dee Why, communities in Manly and Narrabeen differed along temperature/TOC and salinity/silt gradients respectively. In Manly lagoon, we found relatively more anaerobic bacteria such as Epsilonbactereota which is involved in the oxidation and reduction of sulfur compounds. Moreover, we identified several bacterial taxa (including sulfur metabolising...
Fisher, A, Wangpraseurt, D, Larkum, AWD, Johnson, M, Kühl, M, Chen, M, Wong, HL & Burns, BP 2019, 'Correlation of bio-optical properties with photosynthetic pigment and microorganism distribution in microbial mats from Hamelin Pool, Australia.', FEMS microbiology ecology, vol. 95, no. 1.
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Microbial mats and stromatolites are widespread in Hamelin Pool, Shark Bay, however the phototrophic capacity of these systems is unknown. This study has determined the optical properties and light-harvesting potential of these mats with light microsensors. These characteristics were linked via a combination of 16S rDNA sequencing, pigment analyses and hyperspectral imaging. Local scalar irradiance was elevated over the incident downwelling irradiance by 1.5-fold, suggesting light trapping and strong scattering by the mats. Visible light (400-700 nm) penetrated to a depth of 2 mm, whereas near-infrared light (700-800 nm) penetrated to at least 6 mm. Chlorophyll a and bacteriochlorophyll a (Bchl a) were found to be the dominant photosynthetic pigments present, with BChl a peaking at the subsurface (2-4 mm). Detailed 16S rDNA analyses revealed the presence of putative Chl f-containing Halomicronema sp. and photosynthetic members primarily decreased from the mat surface down to a depth of 6 mm. Data indicated high abundances of some pigments and phototrophic organisms in deeper layers of the mats (6-16 mm). It is proposed that the photosynthetic bacteria present in this system undergo unique adaptations to lower light conditions below the mat surface, and that phototrophic metabolisms are major contributors to ecosystem function.
Gardner, SG, Camp, EF, Smith, DJ, Kahlke, T, Osman, EO, Gendron, G, Hume, BCC, Pogoreutz, C, Voolstra, CR & Suggett, DJ 2019, 'Coral microbiome diversity reflects mass coral bleaching susceptibility during the 2016 El Niño heat wave.', Ecology and Evolution, vol. 9, no. 3, pp. 938-956.
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Repeat marine heat wave-induced mass coral bleaching has decimated reefs in Seychelles for 35 years, but how coral-associated microbial diversity (microalgal endosymbionts of the family Symbiodiniaceae and bacterial communities) potentially underpins broad-scale bleaching dynamics remains unknown. We assessed microbiome composition during the 2016 heat wave peak at two contrasting reef sites (clear vs. turbid) in Seychelles, for key coral species considered bleaching sensitive (Acropora muricata, Acropora gemmifera) or tolerant (Porites lutea, Coelastrea aspera). For all species and sites, we sampled bleached versus unbleached colonies to examine how microbiomes align with heat stress susceptibility. Over 30% of all corals bleached in 2016, half of which were from Acropora sp. and Pocillopora sp. mass bleaching that largely transitioned to mortality by 2017. Symbiodiniaceae ITS2-sequencing revealed that the two Acropora sp. and P. lutea generally associated with C3z/C3 and C15 types, respectively, whereas C. aspera exhibited a plastic association with multiple D types and two C3z types. 16S rRNA gene sequencing revealed that bacterial communities were coral host-specific, largely through differences in the most abundant families, Hahellaceae (comprising Endozoicomonas), Rhodospirillaceae, and Rhodobacteraceae. Both Acropora sp. exhibited lower bacterial diversity, species richness, and community evenness compared to more bleaching-resistant P. lutea and C. aspera. Different bleaching susceptibility among coral species was thus consistent with distinct microbiome community profiles. These profiles were conserved across bleached and unbleached colonies of all coral species. As this pattern could also reflect a parallel response of the microbiome to environmental changes, the detailed functional associations will need to be determined in future studies. Further understanding such microbiome-environmental interactions is likely critical to target more effective manag...
Gleason, FH, Larkum, AWD, Raven, JA, Manohar, CS & Lilje, O 2019, 'Ecological implications of recently discovered and poorly studied sources of energy for the growth of true fungi especially in extreme environments', Fungal Ecology, vol. 39, pp. 380-387.
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© 2018 Rhodopsin transmembrane proton pumps (fuelled by visible light which is absorbed by retinal (carotenoid) chromophores) exist in all three domains of living species and in all groups of true fungi studied. Light driven proton and sodium pumps are likely to be essential for some marine fungi, especially hypersaline tolerant and endolithic species. Rhodopsin macromolecular machines, using visible light, drive metabolic reactions in addition to those provided by aerobic respiration, providing extra energy needed for the maintenance and growth of fungi, especially in euphotic environments where oxygen concentration is limited. In addition, dissimilatory nitrate and metal oxide reduction can provide sources of energy for fungi in the absence of oxygen, for example, in fungal species growing in marine sediments. Finally, the oxidation of elemental sulphur, iron and manganese can be a source of energy. Some fungi are, therefore, lithotrophs and photoheterotrophs. The ecological implications of these latter processes are discussed.
Goessling, JW, Su, Y, Maibohm, C, Ellegaard, M & Kuhl, M 2019, 'Differences in the optical properties of valve and girdle band in a centric diatom', INTERFACE FOCUS, vol. 9, no. 1.
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Goyen, S, Camp, EF, Fujise, L, Lloyd, A, Nitschke, MR, LaJeunensse, T, Kahlke, T, Ralph, PJ & Suggett, D 2019, 'Mass coral bleaching of P. versipora in Sydney Harbour driven by the 2015-2016 heatwave', CORAL REEFS, vol. 38, no. 4, pp. 815-830.
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Goyen, S, Camp, EF, Fujise, L, Lloyd, A, Nitschke, MR, LaJeunesse, TC, Kahlke, T, Ralph, PJ & Suggett, D 2019, 'Mass coral bleaching of P. versipora in Sydney Harbour driven by the 2015-2016 heatwave (vol 38, pg 815, 2019)', CORAL REEFS, vol. 38, no. 4, pp. 877-877.
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Gray, R, Jones, HA, Hitchcock, JN, Hardwick, L, Pepper, D, Lugg, A, Seymour, JR & Mitrovic, SM 2019, 'Mitigation of cold-water thermal pollution downstream of a large dam with the use of a novel thermal curtain', River Research and Applications.
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© 2019 John Wiley & Sons, Ltd. Hypolimnial releases from dams during periods of thermal stratification modify the downstream riverine thermal regime by decreasing water temperature and reducing natural diel thermal variability. This cold-water thermal pollution in rivers can persist for hundreds of kilometres downstream of dams and impact important ecological processes such as fish spawning. To mitigate this problem, a first-of-its-kind thermal curtain was fitted to the large bottom release Burrendong Dam on the Macquarie River, Australia. The thermal curtain acts by directing warmer, near-surface epilimnial water to the low-level hypolimnial offtake. This study aimed to test the efficacy of the thermal curtain by measuring temperatures before and after the curtains installation, quantifying the magnitude and extent of cold-water thermal pollution along the Macquarie River downstream of Burrendong Dam. Epilimnial releases with use of the curtain increased diel temperature ranges and the mean monthly water temperature below the dam. Epilimnial releases with use of the curtain increased diel temperature ranges from 0.9°C to 2.5°C and reduced the difference between the mean monthly water temperature of an upstream control and a downstream site by up to 3.5°C. A comparison of the monthly temperature means along the river, indicated that thermal recovery, whereby temperatures returned to within the natural range of upstream temperatures occurred 45 km downstream of the dam during summer when the thermal curtain was deployed, compared with approximately 200 km prior to deployment of the curtain. Our study suggests that the use of thermal curtains can reduce cold-water thermal pollution and improve ecological outcomes for river ecosystems downstream of dams.
Green, TJ, Siboni, N, King, WL, Labbate, M, Seymour, JR & Raftos, D 2019, 'Simulated Marine Heat Wave Alters Abundance and Structure of Vibrio Populations Associated with the Pacific Oyster Resulting in a Mass Mortality Event.', Microbial ecology.
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Marine heat waves are predicted to become more frequent and intense due to anthropogenically induced climate change, which will impact global production of seafood. Links between rising seawater temperature and disease have been documented for many aquaculture species, including the Pacific oyster Crassostrea gigas. The oyster harbours a diverse microbial community that may act as a source of opportunistic pathogens during temperature stress. We rapidly raised the seawater temperature from 20 °C to 25 °C resulting in an oyster mortality rate of 77.4%. Under the same temperature conditions and with the addition of antibiotics, the mortality rate was only 4.3%, strongly indicating a role for bacteria in temperature-induced mortality. 16S rRNA amplicon sequencing revealed a change in the oyster microbiome when the temperature was increased to 25 °C, with a notable increase in the proportion of Vibrio sequences. This pattern was confirmed by qPCR, which revealed heat stress increased the abundance of Vibrio harveyi and Vibrio fortis by 324-fold and 10-fold, respectively. Our findings indicate that heat stress-induced mortality of C. gigas coincides with an increase in the abundance of putative bacterial pathogens in the oyster microbiome and highlights the negative consequences of marine heat waves on food production from aquaculture.
Haro, S, Brodersen, KE, Bohorquez, J, Papaspyrou, S, Corzo, A & Kuhl, M 2019, 'Radiative Energy Budgets in a Microbial Mat Under Different Irradiance and Tidal Conditions', MICROBIAL ECOLOGY, vol. 77, no. 4, pp. 852-865.
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Hoppenrath, M, Kretzschmar, AL, Kaufmann, MJ & Murray, SA 2019, 'Morphological and molecular phylogenetic identification and record verification of Gambierdiscus excentricus (Dinophyceae) from Madeira Island (NE Atlantic Ocean)', Marine Biodiversity Records, vol. 12, no. 1.
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Hurtado-McCormick, V, Kahlke, T, Petrou, K, Jeffries, T, Ralph, PJ & Seymour, JR 2019, 'Regional and Microenvironmental Scale Characterization of the Zostera muelleri Seagrass Microbiome', FRONTIERS IN MICROBIOLOGY, vol. 10.
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Jacques, SL, Wangpraseurt, D & Kuhl, M 2019, 'Optical Properties of Living Corals Determined With Diffuse Reflectance Spectroscopy', FRONTIERS IN MARINE SCIENCE, vol. 6.
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Jaramillo-Madrid, AC, Ashworth, J, Fabris, M & Ralph, PJ 2019, 'Phytosterol biosynthesis and production by diatoms (Bacillariophyceae)', PHYTOCHEMISTRY, vol. 163, pp. 46-57.
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Kahlke, T & Ralph, PJ 2019, 'BASTA – Taxonomic classification of sequences and sequence bins using last common ancestor estimations', Methods in Ecology and Evolution, vol. 10, no. 1, pp. 100-103.
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1. Identification of the taxonomic origin of a DNA sequence is crucial for many sequencing projects, e.g. metagenomics studies, identification of contaminations in whole genome sequencing projects and filtering of organisms of interest in marker‐gene based community analyses.
2. Last common ancestor algorithms are powerful approaches to estimate the taxonomy of a given sequence and have been widely used for classification of next‐generation sequencing (NGS) reads, also known as 2nd generation sequencing reads.
3. Here, we present BASTA (https://github.com/timkahlke/BASTA), a basic sequence taxonomy annotator, which extends last common ancestor estimations from sequencing reads to any kind of nucleotide or amino acid sequence utilizing NCBI taxonomies of user‐defined best hits.
4. BASTA can be configured to use the output of many common sequence comparison tools, e.g. BLAST and Diamond, in conjunction with either provided or user‐defined target sequence databases.
Kim, JH, Kim, H, Kang, D, Lim, YK, Ajani, P, Jung, SW & Baek, SH 2019, 'Field application and validity of a red-tide acoustic sensing system (RASS) for monitoring and alerting of harmful algal blooms (HABs) in Korean coastal waters', Journal of Applied Phycology.
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Kim, M, Pernice, M, Watson-Lazowski, A, Guagliardo, P, Kilburn, MR, Larkum, AWD, Raven, JA & Ralph, PJ 2019, 'Effect of reduced irradiance on 13C uptake, gene expression and protein activity of the seagrass Zostera muelleri.', Marine environmental research, vol. 149, pp. 80-89.
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Photosynthesis in the seagrass Zostera muelleri remains poorly understood. We investigated the effect of reduced irradiance on the incorporation of 13C, gene expression of photosynthetic, photorespiratory and intermediates recycling genes as well as the enzymatic content and activity of Rubisco and PEPC within Z. muelleri. Following 48 h of reduced irradiance, we found that i) there was a ∼7 fold reduction in 13C incorporation in above ground tissue, ii) a significant down regulation of photosynthetic, photorespiratory and intermediates recycling genes and iii) no significant difference in enzyme activity and content. We propose that Z. muelleri is able to alter its physiology in order to reduce the amount of C lost through photorespiration to compensate for the reduced carbon assimilation as a result of reduced irradiance. In addition, the first estimated rate constant (Kcat) and maximum rates of carboxylation (Vcmax) of Rubisco is reported for the first time for Z. muelleri.
King, WL, Jenkins, C, Go, J, Siboni, N, Seymour, JR & Labbate, M 2019, 'Characterisation of the Pacific Oyster Microbiome During a Summer Mortality Event.', Microbial Ecology, vol. 77, pp. 502-512.
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The Pacific oyster, Crassostrea gigas, is a key commercial species that is cultivated globally. In recent years, disease outbreaks have heavily impacted C. gigas stocks worldwide, with many losses incurred during summer. A number of infectious agents have been associated with these summer mortality events, including viruses (particularly Ostreid herpesvirus 1, OsHV-1) and bacteria; however, cases where no known aetiological agent can be identified are common. In this study, we examined the microbiome of disease-affected and disease-unaffected C. gigas during a 2013-2014 summer mortality event in Port Stephens (Australia) where known oyster pathogens including OsHV-1 were not detected. The adductor muscle microbiomes of 70 C. gigas samples across 12 study sites in the Port Stephens estuary were characterised using 16S rRNA (V1-V3 region) amplicon sequencing, with the aim of comparing the influence of spatial location and disease state on the oyster microbiome. Spatial location was found to be a significant determinant of the disease-affected oyster microbiome. Furthermore, microbiome comparisons between disease states identified a significant increase in rare operational taxonomic units (OTUs) belonging to Vibrio harveyi and an unidentified member of the Vibrio genus in the disease-affected microbiome. This is indicative of a potential role of Vibrio species in oyster disease and supportive of previous culture-based examination of this mortality event.
King, WL, Jenkins, C, Seymour, JR & Labbate, M 2019, 'Oyster disease in a changing environment: Decrypting the link between pathogen, microbiome and environment.', Marine environmental research.
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Shifting environmental conditions are known to be important triggers of oyster diseases. The mechanism(s) behind these synergistic effects (interplay between host, environment and pathogen/s) are often not clear, although there is evidence that shifts in environmental conditions can affect oyster immunity, and pathogen growth and virulence. However, the impact of shifting environmental parameters on the oyster microbiome and how this affects oyster health and susceptibility to infectious pathogens remains understudied. In this review, we summarise the major diseases afflicting oysters with a focus on the role of environmental factors that can catalyse or amplify disease outbreaks. We also consider the potential role of the oyster microbiome in buffering or augmenting oyster disease outbreaks and suggest that a deeper understanding of the oyster microbiome, its links to the environment and its effect on oyster health and disease susceptibility, is required to develop new frameworks for the prevention and management of oyster diseases.
King, WL, Siboni, N, Williams, NLR, Kahlke, T, Nguyen, KV, Jenkins, C, Dove, M, O'Connor, W, Seymour, JR & Labbate, M 2019, 'Variability in the Composition of Pacific Oyster Microbiomes Across Oyster Families Exhibiting Different Levels of Susceptibility to OsHV-1 mu var Disease', FRONTIERS IN MICROBIOLOGY, vol. 10.
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Koren, K, Mosshammer, M, Scholz, VV, Borisov, SM, Holst, G & Kuehl, M 2019, 'Luminescence Lifetime Imaging of Chemical Sensors-A Comparison between Time-Domain and Frequency-Domain Based Camera Systems', ANALYTICAL CHEMISTRY, vol. 91, no. 5, pp. 3233-3238.
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Kretzschmar, AL, Verma, A, Murray, S, Kahlke, T, Fourment, M & Darling, A 2019, 'Trial by phylogenetics - Evaluating the Multi-Species Coalescent for phylogenetic inference on taxa with high levels of paralogy (Gonyaulacales, Dinophyceae)'.
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ABSTRACT From publicly available next-gen sequencing datasets of non-model organisms, such as marine protists, arise opportunities to explore their evolutionary relationships. In this study we explored the effects that dataset and model selection have on the phylogenetic inference of the Gonyaulacales, single celled marine algae of the phylum Dinoflagellata with genomes that show extensive paralogy. We developed a method for identifying and extracting single copy genes from RNA-seq libraries and compared phylogenies inferred from these single copy genes with those inferred from commonly used genetic markers and phylogenetic methods. Comparison of two datasets and three different phylogenetic models showed that exclusive use of ribosomal DNA sequences, maximum likelihood and gene concatenation showed very different results to that obtained with the multi-species coalescent. The multi-species coalescent has recently been recognized as being robust to the inclusion of paralogs, including hidden paralogs present in single copy gene sets (pseudoorthologs). Comparisons of model fit strongly favored the multi-species coalescent for these data, over a concatenated alignment (single tree) model. Our findings suggest that the multi-species coalescent (inferred either via Maximum Likelihood or Bayesian Inference) should be considered for future phylogenetic studies of organisms where accurate selection of orthologs is difficult.
Larsson, ME, Harwood, TD, Lewis, RJ, Himaya, SWA & Doblin, MA 2019, 'Toxicological characterization of Fukuyoa paulensis (Dinophyceae) from temperate Australia', Phycological Research, vol. 67, no. 1, pp. 65-71.
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© 2018 Japanese Society of Phycology Dinoflagellates of the genus Gambierdiscus are known to produce neurotoxins that cause the human illness ciguatera, a tropical and sub-tropical fish poisoning. Some species from the Gambierdiscus genus were recently re-classified into a new genus, Fukuyoa based on their phylogenetic and morphological divergence, however, little is known about their distribution, ecology and toxicology. Here we report the first occurrence of F. paulensis in the temperate coastal waters of eastern Australia and characterize its toxicology. Liquid chromatography–tandem mass spectrometry (LC–MS/MS) did not detect the presence of ciguatoxins, however, a putative maitotoxin congener (MTX-3) was present. Similarly, high maitotoxin-like activity was detected in High Performance Liquid Chromatography (HPLC) fractionated cell extracts using a Ca2+ influx bioassay on a Fluorescent Imaging Plate Reader (FLIPR), but no ciguatoxin-like activity was detected.
Larsson, ME, Smith, KF & Doblin, MA 2019, 'First description of the environmental niche of the epibenthic dinoflagellate species Coolia palmyrensis, C. malayensis, and C. tropicalis (Dinophyceae) from Eastern Australia', JOURNAL OF PHYCOLOGY, vol. 55, no. 3, pp. 565-577.
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Leggat, WP, Camp, EF, Suggett, DJ, Heron, SF, Fordyce, AJ, Gardner, S, Deakin, L, Turner, M, Beeching, LJ, Kuzhiumparambil, U, Eakin, CM & Ainsworth, TD 2019, 'Rapid Coral Decay Is Associated with Marine Heatwave Mortality Events on Reefs', CURRENT BIOLOGY, vol. 29, no. 16, pp. 2723-+.
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Leles, SG, Mitra, A, Flynn, KJ, Tillmann, U, Stoecker, D, Jeong, HJ, Burkholder, J, Hansen, PJ, Caron, DA, Glibert, PM, Hallegraeff, G, Raven, JA, Sanders, RW & Zubkov, M 2019, 'Sampling bias misrepresents the biogeographical significance of constitutive mixotrophs across global oceans', GLOBAL ECOLOGY AND BIOGEOGRAPHY, vol. 28, no. 4, pp. 418-428.
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Liao, J, Ye, J, Liang, Y, Khalid, M & Huang, D 2019, 'Pakchoi Antioxidant Improvement and Differential Rhizobacterial Community Composition under Organic Fertilization', SUSTAINABILITY, vol. 11, no. 8.
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Liu, Y, Ge, T, Ye, J, Liu, S, Shibistova, O, Wang, P, Wang, J, Li, Y, Guggenberger, G, Kuzyakov, Y & Wu, J 2019, 'Initial utilization of rhizodeposits with rice growth in paddy soils: Rhizosphere and N fertilization effects', GEODERMA, vol. 338, pp. 30-39.
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Lohr, KE, Camp, EF, Kuzhiumparambil, U, Lutz, A, Leggat, W, Patterson, JT & Suggett, DJ 2019, 'Resolving coral photoacclimation dynamics through coupled photophysiological and metabolomic profiling', JOURNAL OF EXPERIMENTAL BIOLOGY, vol. 222, no. 8.
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Lohr, KE, Khattri, RB, Guingab-Cagmat, J, Camp, EF, Merritt, ME, Garrett, TJ & Patterson, JT 2019, 'Metabolomic profiles differ among unique genotypes of a threatened Caribbean coral', SCIENTIFIC REPORTS, vol. 9.
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Macreadie, PI, Atwood, TB, Seymour, JR, Fontes, MLS, Sanderman, J, Nielsen, DA & Connolly, RM 2019, 'Vulnerability of seagrass blue carbon to microbial attack following exposure to warming and oxygen', Science of the Total Environment, vol. 686, pp. 264-275.
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© 2019 Seagrass meadows store globally-significant quantities of organic ‘blue’ carbon. These blue carbon stocks are potentially vulnerable to anthropogenic stressors (e.g. coastal development, climate change). Here, we tested the impact of oxygen exposure and warming (major consequences of human disturbance) on rates of microbial carbon break-down in seagrass sediments. Active microbes occurred throughout seagrass sediment profiles, but deep, ancient sediments (~5000 yrs. old) contained only 3% of the abundance of active microbes as young, surface sediments (<2 yrs. old). Metagenomic analysis revealed that microbial community structure and function changed with depth, with a shift from proteobacteria and high levels of genes involved in sulfur cycling in the near surface samples, to a higher proportion of firmicutes and euraracheota and genes involved in methanogenesis at depth. Ancient carbon consisted almost entirely (97%) of carbon considered ‘thermally recalcitrant’, and therefore presumably inaccessible to microbial attack. Experimental warming had little impact on carbon; however, exposure of ancient sediments to oxygen increased microbial abundance, carbon uptake and sediment carbon turnover (34–38 fold). Overall, this study provides detailed characterization of seagrass blue carbon (chemical stability, age, associated microbes) and suggests that environmental disturbances that expose coastal sediments to oxygen (e.g. dredging) have the capacity to diminish seagrass sediment carbon stocks by facilitating microbial remineralisation.
McInnes, AS, Laczka, OF, Baker, KG, Larsson, ME, Robinson, CM, Clark, JS, Laiolo, L, Alvarez, M, Laverock, B, Kremer, CT, van Sebille, E & Doblin, MA 2019, 'Live cell analysis at sea reveals divergent thermal performance between photosynthetic ocean microbial eukaryote populations', ISME JOURNAL, vol. 13, no. 5, pp. 1374-1378.
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Meunier, V, Bonnet, S, Pernice, M, Benavides, M, Lorrain, A, Grosso, O, Lambert, C & Houlbrèque, F 2019, 'Bleaching forces coral's heterotrophy on diazotrophs and Synechococcus.', The ISME journal.
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Coral reefs are threatened by global warming, which disrupts the symbiosis between corals and their photosynthetic symbionts (Symbiodiniaceae), leading to mass coral bleaching. Planktonic diazotrophs or dinitrogen (N2)-fixing prokaryotes are abundant in coral lagoon waters and could be an alternative nutrient source for corals. Here we incubated untreated and bleached coral colonies of Stylophora pistillata with a 15N2-pre-labelled natural plankton assemblage containing diazotrophs. 15N2 assimilation rates in Symbiodiniaceae cells and tissues of bleached corals were 5- and 30-fold higher, respectively, than those measured in untreated corals, demonstrating that corals incorporate more nitrogen derived from planktonic diazotrophs under bleaching conditions. Bleached corals also preferentially fed on Synechococcus, nitrogen-rich picophytoplanktonic cells, instead of Prochlorococcus and picoeukaryotes, which have a lower cellular nitrogen content. By providing an alternative source of bioavailable nitrogen, both the incorporation of nitrogen derived from planktonic diazotrophs and the ingestion of Synechococcus may have profound consequences for coral bleaching recovery, especially for the many coral reef ecosystems characterized by high abundance and activity of planktonic diazotrophs.
Moore, LR, Huang, T, Ostrowski, M, Mazard, S, Kumar, SS, Gamage, HKAH, Brown, MV, Messer, LF, Seymour, JR & Paulsen, IT 2019, 'Unicellular Cyanobacteria Are Important Components of Phytoplankton Communities in Australia's Northern Oceanic Ecoregions.', Frontiers in microbiology, vol. 9, pp. 3356-3356.
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The tropical marine environments of northern Australia encompasses a diverse range of geomorphological and oceanographic conditions and high levels of productivity and nitrogen fixation. However, efforts to characterize phytoplankton assemblages in these waters have been restricted to studies using microscopic and pigment analyses, leading to the current consensus that this region is dominated by large diatoms, dinoflagellates, and the marine cyanobacterium Trichodesmium. During an oceanographic transect from the Arafura Sea through the Torres Strait to the Coral Sea, we characterized prokaryotic and eukaryotic phytoplankton communities in surface waters using a combination of flow cytometry and Illumina based 16S and 18S ribosomal RNA amplicon sequencing. Similar to observations in other marine regions around Australian, phytoplankton assemblages throughout this entire region were rich in unicellular picocyanobacterial primary producers while picoeukaryotic phytoplankton formed a consistent, though smaller proportion of the photosynthetic biomass. Major taxonomic groups displayed distinct biogeographic patterns linked to oceanographic and nutrient conditions. Unicellular picocyanobacteria dominated in both flow cytometric abundance and carbon biomass, with members of the Synechococcus genus dominating in the shallower Arafura Sea and Torres Strait where chlorophyll a was relatively higher (averaging 0.4 ± 0.2 mg m-3), and Prochlorococcus dominating in the oligotrophic Coral Sea where chlorophyll a averaged 0.13 ± 0.07 mg m-3. Consistent with previous microscopic and pigment-based observations, we found from sequence analysis that a variety of diatoms (Bacillariophyceae) exhibited high relative abundance in the Arafura Sea and Torres Strait, while dinoflagellates (Dinophyceae) and prymnesiophytes (Prymnesiophyceae) were more abundant in the Coral Sea. Ordination analysis identified temperature, nutrient concentrations and water depth as key drivers of the region'...
Mosshammer, M, Brodersen, KE, Kuhl, M & Koren, K 2019, 'Nanoparticle- and microparticle-based luminescence imaging of chemical species and temperature in aquatic systems: a review', MICROCHIMICA ACTA, vol. 186, no. 2.
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Nguyen, LN, Johir, MAH, Commault, A, Bustamante, H, Aurisch, R, Lowrie, R & Nghiem, LD 2019, 'Impacts of mixing on foaming, methane production, stratification and microbial community in full-scale anaerobic co-digestion process', BIORESOURCE TECHNOLOGY, vol. 281, pp. 226-233.
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Ordoñez, A, Wangpraseurt, D, Lyndby, NH, Kühl, M & Diaz-Pulido, G 2019, 'Elevated CO2 leads to enhanced photosynthesis but decreased growth in early life stages of reef building coralline algae', Frontiers in Marine Science, vol. 5, no. JAN.
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© 2019 Ordoñez, Wangpraseurt, Lyndby, Kühl and Diaz-Pulido. Crustose coralline algae (CCA) are key organisms in coral reef ecosystems, where they contribute to reef building and substrate stabilization. While ocean acidification due to increasing CO2can affect the biology, physiology and ecology of fully developed CCA, the impacts of elevated CO2on the early life stages of CCA are much less explored. We assessed the photosynthetic activity and growth of 10-day-old recruits of the reef-building crustose coralline alga Porolithon cf. onkodes exposed to ambient and enhanced CO2seawater concentration causing a downward shift in pH of ~0.3 units. Growth of the CCA was estimated using measurements of crust thickness and marginal expansion, while photosynthetic activity was studied with O2microsensors. We found that elevated seawater CO2enhanced gross photosynthesis and respiration, but significantly reduced vertical and marginal growth of the early life stages of P. cf. onkodes. Elevated CO2stimulated photosynthesis, particularly at high irradiance, likely due to increased availability of CO2, but this increase did not translate into increased algal growth as expected, suggesting a decoupling of these two processes under ocean acidification scenarios. This study confirms the sensitivity of early stages of CCA to elevated CO2and identifies complexities in the physiological processes underlying the decreased growth and abundance in these important coral reef builders upon ocean acidification.
Pollier, J, Vancaester, E, Kuzhiumparambil, U, Vickers, CE, Vandepoele, K, Goossens, A & Fabris, M 2019, 'A widespread alternative squalene epoxidase participates in eukaryote steroid biosynthesis.', Nature Microbiology, vol. 4, pp. 226-233.
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Steroids are essential triterpenoid molecules that are present in all eukaryotes and modulate the fluidity and flexibility of cell membranes. Steroids also serve as signalling molecules that are crucial for growth, development and differentiation of multicellular organisms1-3. The steroid biosynthetic pathway is highly conserved and is key in eukaryote evolution4-7. The flavoprotein squalene epoxidase (SQE) catalyses the first oxygenation reaction in this pathway and is rate limiting. However, despite its conservation in animals, plants and fungi, several phylogenetically widely distributed eukaryote genomes lack an SQE-encoding gene7,8. Here, we discovered and characterized an alternative SQE (AltSQE) belonging to the fatty acid hydroxylase superfamily. AltSQE was identified through screening of a gene library of the diatom Phaeodactylum tricornutum in a SQE-deficient yeast. In accordance with its divergent protein structure and need for cofactors, we found that AltSQE is insensitive to the conventional SQE inhibitor terbinafine. AltSQE is present in many eukaryotic lineages but is mutually exclusive with SQE and shows a patchy distribution within monophyletic clades. Our discovery provides an alternative element for the conserved steroid biosynthesis pathway, raises questions about eukaryote metabolic evolution and opens routes to develop selective SQE inhibitors to control hazardous organisms.
Raina, JB, Fernandez, V, Lambert, B, Stocker, R & Seymour, JR 2019, 'The role of microbial motility and chemotaxis in symbiosis', Nature Reviews Microbiology.
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© 2019, Springer Nature Limited. Many symbiotic relationships rely on the acquisition of microbial partners from the environment. However, the mechanisms by which microbial symbionts find and colonize their hosts are often unknown. We propose that the acquisition of environmental symbionts often necessitates active migration and colonization by the symbionts through motility and chemotaxis. The pivotal role of these behaviours in the onset and maintenance of symbiotic interactions is well established in a small number of model systems but remains largely overlooked for the many symbioses that involve the recruitment of microbial partners from the environment. In this Review, we highlight when, where and how chemotaxis and motility can enable symbiont recruitment and propose that these symbiont behaviours are important across a wide range of hosts and environments.
Raven, JA, Gobler, CS & Hansen, PJ 2019, 'Dynamic CO 2 and pH levels in coastal, estuarine, and inland waters: Theoretical and observed effects on harmful algal blooms', Harmful Algae.
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© 2019 Elsevier B.V. Rising concentrations of atmospheric CO 2 results in higher equilibrium concentrations of dissolved CO 2 in natural waters, with corresponding increases in hydrogen ion and bicarbonate concentrations and decreases in hydroxyl ion and carbonate concentrations. Superimposed on these climate change effects is the dynamic nature of carbon cycling in coastal zones, which can lead to seasonal and diel changes in pH and CO 2 concentrations that can exceed changes expected for open ocean ecosystems by the end of the century. Among harmful algae, i.e. some species and/or strains of Cyanobacteria, Dinophyceae, Prymnesiophyceae, Bacillariophyceae, and Ulvophyceae, the occurrence of a CO 2 concentrating mechanisms (CCMs) is the most frequent mechanism of inorganic carbon acquisition in natural waters in equilibrium with the present atmosphere (400 μmol CO 2 mol −1 total gas), with varying phenotypic modification of the CCM. No data on CCMs are available for Raphidophyceae or the brown tide Pelagophyceae. Several HAB species and/or strains respond to increased CO 2 concentrations with increases in growth rate and/or cellular toxin content, however, others are unaffected. Beyond the effects of altered C concentrations and speciation on HABs, changes in pH in natural waters are likely to have profound effects on algal physiology. This review outlines the implications of changes in inorganic cycling for HABs in coastal zones, and reviews the knowns and unknowns with regard to how HABs can be expected to ocean acidification. We further point to the large regions of uncertainty with regard to this evolving field.
Rinke, C, Rubino, F, Messer, LF, Youssef, N, Parks, DH, Chuvochina, M, Brown, M, Jeffries, T, Tyson, GW, Seymour, JR & Hugenholtz, P 2019, 'A phylogenomic and ecological analysis of the globally abundant Marine Group II archaea (Ca. Poseidoniales ord. nov.).', The ISME Journal, vol. 13, no. 3, pp. 663-675.
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Marine Group II (MGII) archaea represent the most abundant planktonic archaeal group in ocean surface waters, but our understanding of the group has been limited by a lack of cultured representatives and few sequenced genomes. Here, we conducted a comparative phylogenomic analysis of 270 recently available MGII metagenome-assembled genomes (MAGs) to investigate their evolution and ecology. Based on a rank-normalised genome phylogeny, we propose that MGII is an order-level lineage for which we propose the name Candidatus Poseidoniales (after Gr. n. Poseidon, God of the sea), comprising the families Candidatus Poseidonaceae fam. nov. (formerly subgroup MGIIa) and Candidatus Thalassarchaeaceae fam. nov. (formerly subgroup MGIIb). Within these families, 21 genera could be resolved, many of which had distinct biogeographic ranges and inferred nutrient preferences. Phylogenetic analyses of key metabolic functions suggest that the ancestor of Ca. Poseidoniales was a surface water-dwelling photoheterotroph that evolved to occupy multiple related ecological niches based primarily on spectral tuning of proteorhodopsin genes. Interestingly, this adaptation appears to involve an overwrite mechanism whereby an existing single copy of the proteorhodopsin gene is replaced by a horizontally transferred copy, which in many instances should allow an abrupt change in light absorption capacity. Phototrophy was lost entirely from five Ca. Poseidoniales genera coinciding with their adaptation to deeper aphotic waters. We also report the first instances of nitrate reductase in two genera acquired via horizontal gene transfer (HGT), which was a potential adaptation to oxygen limitation. Additional metabolic traits differentiating families and genera include flagellar-based adhesion, transporters, and sugar, amino acid, and peptide degradation. Our results suggest that HGT has shaped the evolution of Ca. Poseidoniales to occupy a variety of ecological niches and to become the most succes...
Segečová, A, Pérez-Bueno, ML, Barón, M, Červený, J & Roitsch, TG 2019, 'Noninvasive determination of toxic stress biomarkers by high-throughput screening of photoautotrophic cell suspension cultures with multicolor fluorescence imaging.', Plant methods, vol. 15, p. 100.
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Background:With increasing pollution, herbicide application and interest in plant phenotyping, sensors capturing early responses to toxic stress are demanded for screening susceptible or resistant plant varieties. Standard toxicity tests on plants are laborious, demanding in terms of space and material, and the measurement of growth-inhibition based endpoints takes relatively long time. The aim of this work was to explore the potential of photoautotrophic cell suspension cultures for high-throughput early toxicity screening based on imaging techniques. The investigation of the universal potential of fluorescence imaging methods involved testing of three toxicants with different modes of action (DCMU, glyphosate and chromium). Results:The increased pace of testing was achieved by using non-destructive imaging methods-multicolor fluorescence (MCF) and chlorophyll fluorescence (ChlF). These methods detected the negative effects of the toxicants earlier than it was reflected in plant growth inhibition (decrease in leaf area and final dry weight). Moreover, more subtle and transient effects not resulting in growth inhibition could be detected by fluorescence. The pace and sensitivity of stress detection was further enhanced by using photoautotrophic cell suspension cultures. These reacted sooner, more pronouncedly and to lower concentrations of the tested toxicants than the plants. Toxicant-specific stress signatures were observed as a combination of MCF and ChlF parameters and timing of the response. Principal component analysis was found to be useful for reduction of the collected multidimensional data sets to a few informative parameters allowing comparison of the toxicant signatures. Conclusions:Photoautotrophic cell suspension cultures have proved to be useful for rapid high-throughput screening of toxic stress and display a potential for employment as an alternative to tests on whole plants. The MCF and ChlF methods are capable of distinguishing early stress sig...
Seguro, I, Marca, AD, Painting, SJ, Shutler, JD, Suggett, DJ & Kaiser, J 2019, 'High-resolution net and gross biological production during a Celtic Sea spring bloom', Progress in Oceanography.
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© 2017 The Authors Shelf seas represent only 10% of the ocean area, but support up to 30% of all oceanic primary production. There are few measurements of shelf-sea biological production at high spatial and temporal resolution in such heterogeneous and physically dynamic systems. Here, we use dissolved oxygen-to-argon (O2/Ar) ratios and oxygen triple isotopes (16O, 17O, 18O) to estimate net and gross biological production in the Celtic Sea during spring 2015. O2/Ar ratios were measured continuously using a shipboard membrane inlet mass spectrometer (MIMS). Additional discrete water samples from CTD hydrocasts were used to measure O2/Ar depth profiles and the δ(17O) and δ(18O) values of dissolved O2. These high-resolution data were combined with wind-speed based gas exchange parameterisations to calculate biologically driven air-sea oxygen fluxes. After correction for disequilibrium terms and diapycnal diffusion, these fluxes yielded estimates of net community (N(O2/Ar)) and gross O2 production (G(17O)). N(O2/Ar) was spatially heterogeneous and showed predominantly autotrophic conditions, with an average of (33 ± 41) mmol m−2 d−1. G(17O) showed high variability between 0 and 424 mmol m−2 d−1. The ratio of N(O2/Ar) to G(17O), ƒ(O2), was (0.18 ± 0.03) corresponding to 0.34 ± 0.06 in carbon equivalents. We also observed rapid temporal changes in N(O2/Ar), e.g. an increase of 80 mmol m−2 d−1 in <6 h during the spring bloom, highlighting the importance of high-resolution biological production measurements. Such measurements will help reconcile the differences between satellite and in situ productivity observations, and improve our understanding of the biological carbon pump.
Simoniello, C, Jencks, J, Lauro, FM, Loftis, JD, Weslawski, JM, Deja, K, Forrest, DR, Gossett, S, Jeffries, TC, Jensen, RM, Kobara, S, Nolan, L, Ostrowski, M, Pounds, D, Roseman, G, Basco, O, Gosselin, S, Reed, A, Wills, P & Wyatt, D 2019, 'Citizen-science for the future: Advisory case studies from around the globe', Frontiers in Marine Science, vol. 6, no. May.
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© 2019 Simoniello, Jencks, Lauro, Loftis, Weslawski, Deja, Forrest, Gossett, Jeffries, Jensen, Kobara, Nolan, Ostrowski, Pounds, Roseman, Basco, Gosselin, Reed, Wills and Wyatt. The democratization of ocean observation has the potential to add millions of observations every day. Though not a solution for all ocean monitoring needs, citizen scientists offer compelling examples showcasing their ability to augment and enhance traditional research and monitoring. Information they are providing is increasing the spatial and temporal frequency and duration of sampling, reducing time and labor costs for academic and government monitoring programs, providing hands-on STEM learning related to real-world issues and increasing public awareness and support for the scientific process. Examples provided here demonstrate the wide range of people who are already dramatically reducing gaps in our global observing network while at the same time providing unique opportunities to meaningfully engage in ocean observing and the research and conservation it supports. While there are still challenges to overcome before widespread inclusion in projects requiring scientific rigor, the growing organization of international citizen science associations is helping to reduce barriers. The case studies described support the idea that citizen scientists should be part of an effective global strategy for a sustained, multidisciplinary and integrated observing system.
Simoniello, C, Jencks, J, Lauro, FM, Loftis, JD, Weslawski, JM, Deja, K, Forrest, DR, Gossetts, S, Jeffries, TC, Jensen, RM, Kobara, S, Nolan, L, Ostrowski, M, Pounds, D, Roseman, G, Basco, O, Gosselin, S, Reed, A, Wills, P & Wyatt, D 2019, 'Citizen-Science for the Future: Advisory Case Studies From Around the Globe', Frontiers in Marine Science, vol. 6.
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Smith, MN, Stark, SC, Taylor, TC, Ferreira, ML, de Oliveira, E, Restrepo-Coupe, N, Chen, S, Woodcock, T, dos Santos, DB, Alves, LF, Figueira, M, de Camargo, PB, de Oliveira, RC, Aragao, LEOC, Falk, DA, McMahon, SM, Huxman, TE & Saleska, SR 2019, 'Seasonal and drought-related changes in leaf area profiles depend on height and light environment in an Amazon forest', NEW PHYTOLOGIST, vol. 222, no. 3, pp. 1284-1297.
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Sproles, AE, Oakley, CA, Matthews, JL, Peng, L, Owen, JG, Grossman, AR, Weis, VM & Davy, SK 2019, 'Proteomics quantifies protein expression changes in a model cnidarian colonised by a thermally tolerant but suboptimal symbiont', ISME JOURNAL, vol. 13, no. 9, pp. 2334-2345.
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Suggett, DJ, Camp, EF, Edmondson, J, Bostrom-Einarsson, L, Ramler, V, Lohr, K & Patterson, JT 2019, 'Optimizing return-on-effort for coral nursery and outplanting practices to aid restoration of the Great Barrier Reef', RESTORATION ECOLOGY, vol. 27, no. 3, pp. 683-693.
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Sutherland, DL & Ralph, PJ 2019, 'Microalgal bioremediation of emerging contaminants - Opportunities and challenges.', Water research, vol. 164, p. 114921.
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Emerging contaminants (ECs) are primarily synthetic organic chemicals that have a focus of increasing attention due to either increased awareness of their potential risks to humans and aquatic biota, or only recently been detected in the aquatic environment or drinking water supplies, through improved analytical techniques. . Many ECs have no regulatory standards due to the lack of information on the effects of chronic exposure. Pharmaceuticals, personal care products, pesticides and flame retardants are some of the most frequently detected ECs in aquatic environments, with over 200 individual compounds identified, to date. Current wastewater treatment is ineffective at removing ECs and there is a vital need for the development of efficient, cost-effective EC treatment systems that can be applied to a range of scales and wastewater types. Microalgae have demonstrated potential for detoxifying organic and inorganic pollutants, with a number of large-scale wastewater treatment microalgal technologies already developed. There are three main pathways that microalgae can bioremediate ECs; bioadsorption, bio-uptake and biodegradation. Microalgal bioadsorption occurs when ECs are either adsorbed to cell wall components, or onto organic substances excreted by the cells, while bio-uptake involves the active transport of the contaminant into the cell, where it binds to intracellular proteins and other compounds. Microalgal biodegradation of ECs involves the transformation of complex compounds into simpler breakdown molecules through catalytic metabolic degradation. Biodegradation provides one of the most promising technologies for the remediation of contaminants of concern as it can transform the contaminant to less toxic compounds rather than act as a biofilter. Further research is needed to exploit microalgal species for EC bioremediation properties, such as increased bioadsorption, enhanced biodegrading enzymes and optimised growth conditions. When coupled with nutrient...
Tan, ZH, Zhao, JF, Wang, GZ, Chen, MP, Yang, LY, He, CS, Restrepo-Coupe, N, Peng, SS, Liu, XY, da Rocha, HR, Kosugi, Y, Hirano, T, Saleska, SR, Goulden, ML, Zeng, J, Ding, FJ, Gao, F & Song, L 2019, 'Surface conductance for evapotranspiration of tropical forests: Calculations, variations, and controls', Agricultural and Forest Meteorology, vol. 275, pp. 317-328.
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© 2019 Elsevier B.V. Tropical forests are responsible for the evaporation and transpiration of large quantities of water into the atmosphere annually. Surface conductance (gs) is a poorly understood phenomenon that plays a central role in regulating this evapotranspiration. We studied the calculations, variations, and environmental factors controlling gs based on eddy flux measurements from 10 tropical forest sites that covered a wide range of water gradients across continents. We found that boundary layer conductance (gb) is comparable with aerodynamic conductance for momentum (gaM) and thus, it should not be ignored in estimations of total aerodynamic conductance for water vapor (gaV). Based on the findings, we have made some recommendations for gaM estimation both with and without measurements of turbulence. The seasonal variation of gs is low in humid sites but large in sites with a dry season. A value of 24.8 ± 13.8 mm s−1 was suggested for maximum surface conductance (gsmax) for tropical forests. Both water vapor deficit (D) and radiation (Q) play an important role in controlling gs. The model driven by both D and Q could capture the diurnal variations of gs well and could be implemented in large-scale models in future. We believe the findings of this study could contribute substantially to our understanding of tropical forest gs.
Thomson, A, Trevathan-Tackett, S, Ralph, P, Macreadie, P & Maher, D 2019, 'Bioturbator-stimulated loss of seagrass sediment carbon stocks', Limnology and Oceanography, vol. 64, pp. 342-356.
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Seagrass ecosystems are highly productive, and are sites of significant carbon sequestration. Sediment‐held carbon stocks can be many thousands of years old, and persist largely due to sediment anoxia and because microbial activity is decreasing with depth. However, the carbon sequestered in seagrass ecosystems may be susceptible to remineralization via the activity of bioturbating fauna. Microbial priming is a process whereby remineralization of sediment carbon (recalcitrant organic matter) is stimulated by disturbance, i.e., burial of a labile source of organic matter (seagrass). We investigated the hypothesis that bioturbation could mediate remineralization of sediment carbon stocks through burial of seagrass leaf detritus. We carried out a 2‐month laboratory study to compare the remineralization (measured as CO2 release) of buried seagrass leaves (Zostera muelleri) to the total rate of sediment organic matter remineralization in sediment with and without the common Australian bioturbating shrimp Trypaea australiensis (Decapoda: Axiidea). In control sediment containing seagrass but no bioturbators, we observed a negative microbial priming effect, whereby seagrass remineralization was favored over sediment remineralization (and thus preserving sediment stocks). Bioturbation treatments led to a two‐ to five‐fold increase in total CO2 release compared to controls. The estimated bioturbator‐stimulated microbial priming effect was equivalent to 15% of the total daily sediment‐derived CO2 releases. We propose that these results indicate that bioturbation is a potential mechanism that converts these sediments from carbon sinks to sources through stimulation of priming‐enhanced sediment carbon remineralization. We further hypothesized that significant changes to seagrass faunal communities may influence seagrass sediment carbon stocks.
Verma, A, Barua, A, Ruvindy, R, Savela, H, Ajani, PA & Murray, SA 2019, 'The Genetic Basis of Toxin Biosynthesis in Dinoflagellates.', Microorganisms, vol. 7, no. 8.
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In marine ecosystems, dinoflagellates can become highly abundant and even dominant at times, despite their comparatively slow growth rates. One factor that may play a role in their ecological success is the production of complex secondary metabolite compounds that can have anti-predator, allelopathic, or other toxic effects on marine organisms, and also cause seafood poisoning in humans. Our knowledge about the genes involved in toxin biosynthesis in dinoflagellates is currently limited due to the complex genomic features of these organisms. Most recently, the sequencing of dinoflagellate transcriptomes has provided us with valuable insights into the biosynthesis of polyketide and alkaloid-based toxin molecules in dinoflagellate species. This review synthesizes the recent progress that has been made in understanding the evolution, biosynthetic pathways, and gene regulation in dinoflagellates with the aid of transcriptomic and other molecular genetic tools, and provides a pathway for future studies of dinoflagellates in this exciting omics era.
Verma, A, Kohli, GS, Harwood, DT, Ralph, PJ & Murray, SA 2019, 'Transcriptomic investigation into polyketide toxin synthesis in Ostreopsis (Dinophyceae) species.', Environmental microbiology.
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In marine ecosystems, dinoflagellates can become highly abundant and even dominant at times, despite their comparatively slow growth. Their ecological success may be related to their production of complex toxic polyketide compounds. Ostreopsis species produce potent palytoxin-like compounds (PLTX), which are associated with human skin and eye irritations, and illnesses through the consumption of contaminated seafood. To investigate the genetic basis of PLTX-like compounds, we sequenced and annotated transcriptomes from two PLTX-producing Ostreopsis species; O. cf. ovata, O. cf. siamensis, one non-PLTX producing species, O. rhodesae and compared them to a close phylogenetic relative and non-PLTX producer, Coolia malayensis. We found no clear differences in the presence or diversity of ketosynthase and ketoreductase transcripts between PLTX producing and non-producing Ostreopsis and Coolia species, as both groups contained >90 and > 10 phylogenetically diverse ketosynthase and ketoreductase transcripts, respectively. We report for the first-time type I single-, multi-domain polyketide synthases (PKSs) and hybrid non-ribosomal peptide synthase/PKS transcripts from all species. The long multi-modular PKSs were insufficient by themselves to synthesize the large complex polyether backbone of PLTX-like compounds. This implies that numerous PKS domains, including both single and multi-, work together on the biosynthesis of PLTX-like and other related polyketide compounds.
Wangpraseurt, D, Jacques, S, Lyndby, N, Holm, JB, Pages, CF & Kuhl, M 2019, 'Microscale light management and inherent optical properties of intact corals studied with optical coherence tomography', JOURNAL OF THE ROYAL SOCIETY INTERFACE, vol. 16, no. 151.
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Wangpraseurt, D, Lichtenberg, M, Jacques, SL, Larkum, AWD & Kuehl, M 2019, 'Optical Properties of Corals Distort Variable Chlorophyll Fluorescence Measurements', PLANT PHYSIOLOGY, vol. 179, no. 4, pp. 1608-1619.
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Watson, CJ, Restrepo-Coupe, N & Huete, AR 2019, 'Multi-scale phenology of temperate grasslands: Improving monitoring and management with near-surface phenocams', Frontiers in Environmental Science, vol. 7, no. FEB.
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© 2019 Watson, Restrepo-Coupe and Huete. Grasslands of the Australian Southern Tablelands represent a patchwork of native and exotic systems, occupying a continuum of C 3 -dominated to C 4 -dominated grasslands where composition depends on disturbance factors (e.g., grazing) and climate. Managing these complex landscapes is both challenging and critical for maintaining the security of Australia's pasture industries, and for protecting the biodiversity of native remnants. Differentiating C 3 from C 4 vegetation has been a prominent theme in remote sensing research due to distinct C 3 /C 4 seasonal productivity patterns (phenology) and high uncertainty about how C 3 /C 4 vegetation will respond to a changing climate. Phenology is used in northern hemisphere ecosystems for a range of purposes but has not been widely adopted in Australia, where dynamic climate often results in non-repetitive seasonal vegetation patterns. We employed time-lapse cameras (phenocams) to study the phenology of twelve grassland areas dominated by cool season (C 3 ) and warm season (C 4 ), native or exotic grasses near Canberra, Australia. Our aims were to assess phenological characteristics of the functional types and to determine the drivers of phenological variability. We compared the fine-scale phenocam seasonal profiles with field sampling and MODIS/Landsat satellite products to assess paddock-to-landscape functioning. We found C 3 /C 4 species dominance to be the primary driver of phenological differences among grassland types, with C 3 grasslands demonstrating peak greenness in spring, and senescing rapidly in response to high summer temperatures. In contrast, C 4 grasslands showed peak activity in Austral summer and autumn (January-March). Some sites displayed primary and secondary peaks dependent on rainfall and species composition. We found that the proportion of dead vegetation is an important biophysical driver of grassland phenology, as were grazing pressures and species-depen...
You, F, Zhang, L, Ye, J & Huang, L 2019, 'Microbial decomposition of biomass residues mitigated hydrogeochemical dynamics in strongly alkaline bauxite residues', SCIENCE OF THE TOTAL ENVIRONMENT, vol. 663, pp. 216-226.
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Zhu, Y, Suggett, DJ, Liu, C, He, J, Lin, L, Le, F, Ishizaka, J, Goes, J & Hao, Q 2019, 'Primary productivity dynamics in the summer Arctic Ocean confirms broad regulation of the electron requirement for carbon fixation by light-phytoplankton community interaction', Frontiers in Marine Science, vol. 6, no. May.
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© 2019 Zhu, Suggett, Liu, He, Lin, Le, Ishizaka, Goes and Hao. Predicting conversion of photosynthetic electron transport to inorganic carbon uptake rates (the so-called electron requirement for carbon fixation, KC) is central to the broad scale deployment of Fast Repetition Rate fluorometry (FRRf) for primary productivity studies. However, reconciling variability of KC over space and time to produce robust algorithms remains challenging, given the large number of factors that influence KC. We have previously shown that light appears to be a proximal driver of Kc in several ocean regions and we therefore examined whether and how light similarly regulated KC variability in the Arctic Ocean, during a summer cruise in 2016. Sampling transited ice-free and ice-covered waters, with temperature, salinity and Chl-a concentrations all higher for the ice-free than ice covered surface waters. Micro- and pico-phytoplankton generally dominated the ice-free and ice-covered waters, respectively. Values of KC, determined from parallel measures of daily integrated electron transport rates and 14C-uptake, were overall lower for the ice-covered vs. ice-free stations. As in our previous studies, KC was strongly linearly correlated to daily PAR (r = 0.68, n = 46, p < 0.001) and this relationship could be further improved (r = 0.84, n = 46, p < 0.001) by separating samples into ice-free (micro-phytoplankton dominated) vs. ice-covered (Nano- and Pico-phytoplankton dominated water. We subsequently contrasted the PAR-KC relationship form the Arctic waters with the previous relationships from the Ariake Bay and East China Sea and revealed that these various PAR-KC relationships can be systematically explained across regions by phytoplankton community size structures. Specifically, the value of the linear slope describing PAR-KC decreases as water bodies have an increasing fraction of larger phytoplankton. We propose that this synoptic trend reflects how phytoplankton community structure ...