ORCID Profile
0000-0001-8750-3433
Current Organisation
University of Technology Sydney
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Biological Oceanography | Marine and Estuarine Ecology (incl. Marine Ichthyology) | Oceanography | Biochemistry And Cell Biology Not Elsewhere Classified | Ecology | Microbiology | Microbial Ecology | Environmental Monitoring | Infectious Diseases | Biological Oceanography | Chemical Oceanography | Global Change Biology | Evolutionary Impacts of Climate Change | Other Chemical Sciences | Clinical Sciences | Ecological Impacts of Climate Change | Other Biological Sciences | Environmental Impact Assessment | Environmental Chemistry (incl. Atmospheric Chemistry) | Infectious Agents |
ANZSRC Socio-Economic Objective (SEO)
Ecosystem Assessment and Management of Coastal and Estuarine Environments | Marine Flora, Fauna and Biodiversity | Ecosystem Assessment and Management of Marine Environments | Effects of Climate Change and Variability on Australia (excl. Social Impacts) | Marine Oceanic Processes (excl. climate related) | Oceanic processes (excl. climate related) | Coastal and Marine Management Policy | Ecosystem Adaptation to Climate Change | Living resources (flora and fauna) | Coastal and Estuarine Flora, Fauna and Biodiversity | Control of Animal Pests, Diseases and Exotic Species in Coastal and Estuarine Environments | Climate Change Models | Infectious diseases | Endocrine organs and diseases (incl. diabetes) | Estuarine and lagoon areas | Living resources (incl. impacts of fishing on non-target species) | Fisheries - Wild Caught not elsewhere classified | Expanding Knowledge in the Biological Sciences | Other
Related Links
Publications
Contrasting microbial assemblages in adjacent water masses associated with the East Australian Current
Publisher: Wiley
Date: 27-06-2012
DOI: 10.1111/J.1758-2229.2012.00362.X
Abstract: Different oceanographic provinces host discrete microbial assemblages that are adapted to local physicochemical conditions. We sequenced and compared the metagenomes of two microbial communities inhabiting adjacent water masses in the Tasman Sea, where the recent strengthening of the East Australian Current (EAC) has altered the ecology of coastal environments. Despite the comparable latitude of the s les, significant phylogenetic differences were apparent, including shifts in the relative frequency of matches to Cyanobacteria, Crenarchaeota and Euryarchaeota. Fine-scale variability in the structure of SAR11, Prochlorococcus and Synechococcus populations, with more matches to 'warm-water' ecotypes observed in the EAC, indicates the EAC may drive an intrusion of tropical microbes into temperate regions of the Tasman Sea. Furthermore, significant shifts in the relative importance of 17 metabolic categories indicate that the EAC prokaryotic community has different physiological properties than surrounding waters.
Roadmaps and Detours: Active Chlorophyll-a Assessments of Primary Productivity Across Marine and Freshwater Systems
Publisher: American Chemical Society (ACS)
Date: 24-09-2018
Abstract: Assessing phytoplankton productivity over space and time remains a core goal for oceanographers and limnologists. Fast Repetition Rate fluorometry (FRRf) provides a potential means to realize this goal with unprecedented resolution and scale yet has not become the "go-to" method despite high expectations. A major obstacle is difficulty converting electron transfer rates to equivalent rates of C-fixation most relevant for studies of biogeochemical C-fluxes. Such difficulty stems from methodological inconsistencies and our limited understanding of how the electron requirement for C-fixation (Φ
Setting a size-exclusion limit to remove toxic dinoflagellate cysts from ships’ ballast water
Publisher: Elsevier BV
Date: 03-2006
DOI: 10.1016/J.MARPOLBUL.2005.12.014
Abstract: Dinoflagellate cysts are well-recognized biological constituents of ships' ballast tanks. They are present in ballast water, sediments and residual water in drained tanks, and in biofilms formed on interior tank surfaces. Therefore, cysts have the potential to be released during ballast discharge. The International Maritime Organization's (IMO) Ballast Water Management Convention (promulgated February 2004) stipulates a performance standard (Annex, Regulation D2) requiring discharged ballast water contain <10 viable organisms between 10 and 50 microm per ml and <10 viable organisms 50 microm per m3. The proposed size limit has potential to exclude both the smallest toxic and the largest toxic and non-toxic dinoflagellate (and other microalgal) cysts from discharged ballast water. Despite the appropriateness of size cutoffs however, ballast water containing predominantly small cysts ( 50 microm) could require a multiple-log reduction in abundance before its permissible discharge. Also of concern, it remains uncertain whether ballast-water treatment can remove sufficient organisms, including dinoflagellate cysts, to meet the performance standard.
Mucospheres produced by a mixotrophic protist impact ocean carbon cycling
Publisher: Springer Science and Business Media LLC
Date: 14-03-2022
DOI: 10.1038/S41467-022-28867-8
Abstract: Mixotrophic protists (unicellular eukaryotes) that engage in both phototrophy (photosynthesis) and phago-heterotrophy (engulfment of particles)—are predicted to contribute substantially to energy fluxes and marine biogeochemical cycles. However, their impact remains largely unquantified. Here we describe the sophisticated foraging strategy of a widespread mixotrophic dinoflagellate, involving the production of carbon-rich ‘mucospheres’ that attract, capture, and immobilise microbial prey facilitating their consumption. We provide a detailed characterisation of this previously undescribed behaviour and reveal that it represents an overlooked, yet quantitatively significant mechanism for oceanic carbon fluxes. Following feeding, the mucospheres laden with surplus prey are discarded and sink, contributing an estimated 0.17–1.24 mg m −2 d −1 of particulate organic carbon, or 0.02–0.15 Gt to the biological pump annually, which represents 0.1–0.7% of the estimated total export from the euphotic zone. These findings demonstrate how the complex foraging behaviour of a single species of mixotrophic protist can disproportionally contribute to the vertical flux of carbon in the ocean.
Long-term perspective on the relationship between phytoplankton and nutrient concentrations in a southeastern Australian estuary
Publisher: Elsevier BV
Date: 2017
DOI: 10.1016/J.MARPOLBUL.2016.09.011
Abstract: Sixteen years (1997-2013) of physicochemical, nutrient and phytoplankton biomass (Chlorophyll-a (Chl-a)) data and a decade (2003-2013) of phytoplankton composition and abundance data were analyzed to assess how the algal community in a temperate southeastern Australian estuary has responded to decreased chronic point source nitrogen loading following effluent treatment upgrade works in 2003. Nitrogen concentrations were significantly lower (P<0.05) following enhanced effluent treatment and Chl-a levels decreased (P<0.05) during the warmer months. Temperature and nutrient concentrations significantly influenced temporal changes of Chl-a (explaining 55% of variability), while salinity, temperature, pH and nutrient concentrations influenced phytoplankton abundance and composition (25% explained). Harmful Algal Bloom (HAB) dynamics differed between sites likely influenced by physical attributes of the estuary. This study demonstrates that enhanced effluent treatment can significantly decrease chronic point source nitrogen loading and that Chl-a concentrations can be lowered during the warmer months when the risk of blooms and HABs is greatest.
Hitchhiking in the East Australian Current: rafting as a dispersal mechanism for harmful epibenthic dinoflagellates
Publisher: Inter-Research Science Center
Date: 09-02-2023
DOI: 10.3354/MEPS12579
Application of an ELISA-type amperometric assay to the detection of Vibrio species with screen-printed electrodes
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3AY42169D
Abstract: Electrochemical detection of Vibrio parahaemolyticus cells at a minimum abundance of 4 × 10 2 cells per mL within 60 min.
Theory and Application of Pulse Amplitude Modulated Chlorophyll Fluorometry in Coral Health Assessment
Publisher: Wiley
Date: 02-10-2015
Reduced performance of native infauna following recruitment to a habitat-forming invasive marine alga
Publisher: Springer Science and Business Media LLC
Date: 22-10-2008
DOI: 10.1007/S00442-008-1181-0
Abstract: Despite well-documented negative impacts of invasive species on native biota, evidence for the facilitation of native organisms, particularly by habitat-forming invasive species, is increasing. However, most of these studies are conducted at the population or community level, and we know little about the in idual fitness consequences of recruitment to habitat-forming invasive species and, consequently, whether recruitment to these habitats is adaptive. We determined the consequences of recruitment to the invasive green alga Caulerpa taxifolia on the native soft-sediment bivalve Anadara trapezia and nearby unvegetated sediment. Initially, we documented the growth and survivorship of A. trapezia following a natural recruitment event, to which recruitment to C. taxifolia was very high. After 12 months, few clams remained in either habitat, and those that remained showed little growth. Experimental manipulations of recruits demonstrated that all performance measures (survivorship, growth and condition) were significantly reduced in C. taxifolia sediments compared to unvegetated sediments. Exploration of potential mechanisms responsible for the reduced performance in C. taxifolia sediments showed that water flow and water column dissolved oxygen (DO) were significantly reduced under the canopy of C. taxifolia and that sediment anoxia was significantly higher and sediment sulphides greater in C. taxifolia sediments. However, phytoplankton abundance (an indicator of food supply) was significantly higher in C. taxifolia sediments than in unvegetated ones. Our results demonstrate that recruitment of native species to habitat-forming invasive species can reduce growth, condition and survivorship and that studies conducted at the community level may lead to erroneous conclusions about the impacts of invaders and should include studies on life-history traits, particularly juveniles.
First description of the environmental niche of the epibenthic dinoflagellate species Coolia palmyrensis, C. malayensis, and C. tropicalis (Dinophyceae) from Eastern Australia
Publisher: Wiley
Date: 22-02-2019
DOI: 10.1111/JPY.12833
Abstract: Environmental variables such as temperature, salinity, and irradiance are significant drivers of microalgal growth and distribution. Therefore, understanding how these variables influence fitness of potentially toxic microalgal species is particularly important. In this study, strains of the potentially harmful epibenthic dinoflagellate species Coolia palmyrensis, C. malayensis, and C. tropicalis were isolated from coastal shallow water habitats on the east coast of Australia and identified using the D1-D3 region of the large subunit (LSU) ribosomal DNA (rDNA). To determine the environmental niche of each taxon, growth was measured across a gradient of temperature (15-30°C), salinity (20-38), and irradiance (10-200 μmol photons · m
Multiplex PCR allows simultaneous detection of pathogens in ships' ballast water
Publisher: Elsevier BV
Date: 06-2004
Thresholds for tracing ships’ ballast water: an Australian case study
Publisher: Inter-Research Science Center
Date: 03-06-2010
DOI: 10.3354/MEPS08599
Phytoplankton absorption predicts patterns in primary productivity in Australian coastal shelf waters
Publisher: Elsevier BV
Date: 06-2017
Assessing and evaluating the ocean-colour footprint of a regional observing system
Publisher: Elsevier BV
Date: 03-2015
Snapshot prediction of carbon productivity, carbon and protein content in a Southern Ocean diatom using FTIR spectroscopy
Publisher: Springer Science and Business Media LLC
Date: 31-07-2016
Effect of copper on multiple successional stages of a marine fouling assemblage
Publisher: Informa UK Limited
Date: 30-10-2017
DOI: 10.1080/08927014.2017.1384468
Abstract: Copper based paints are used to prevent fouling on the hulls of ships. The widely documented effect of copper on hull assemblages may be primarily due to direct effects on the invertebrates themselves or indirect effects from copper absorbed into the microbial biofilm before settlement has commenced. Artificial units of habitat were exposed to varied regimes of copper to examine (1) the photosynthetic efficiency and pigments of early-colonising biofilms, and (2) subsequent macroinvertebrate assemblage change in response to the different regimes of copper. Macroinvertebrate assemblages were found to be less sensitive to the direct effects of copper than indirect effects as delivered through biofilms that have been historically exposed to copper, with some species more tolerant than others. This raises further concern for the efficacy of copper as a universal antifoulant on the hulls of ships, which may continue to assist the invasion of copper-tolerant invertebrate species.
Multivariate trait analysis reveals diatom plasticity constrained to a reduced set of biological axes
Publisher: Springer Science and Business Media LLC
Date: 25-10-2021
DOI: 10.1038/S43705-021-00062-8
Abstract: Trait-based approaches to phytoplankton ecology have gained traction in recent decades as phenotypic traits are incorporated into ecological and biogeochemical models. Here, we use high-throughput phenotyping to explore both intra- and interspecific constraints on trait combinations that are expressed in the cosmopolitan marine diatom genus Thalassiosira . We demonstrate that within Thalassiosira , phenotypic ersity cannot be predicted from genotypic ersity, and moreover, plasticity can create highly ergent phenotypes that are incongruent with taxonomic grouping. Significantly, multivariate phenotypes can be represented in reduced dimensional space using principal component analysis with 77.7% of the variance captured by two orthogonal axes, here termed a ‘trait-scape’. Furthermore, this trait-scape can be recovered with a reduced set of traits. Plastic responses to the new environments expanded phenotypic trait values and the trait-scape, however, the overall pattern of response to the new environments was similar between strains and many trait correlations remained constant. These findings demonstrate that trait-scapes can be used to reveal common constraints on multi-trait plasticity in phytoplankton with ergent underlying phenotypes. Understanding how to integrate trait correlational constraints and trade-offs into theoretical frameworks like biogeochemical models will be critical to predict how microbial responses to environmental change will impact elemental cycling now and into the future.
Phytoplankton Functional Groups Variation and Influencing Factors in a Shallow Temperate Lake
Publisher: Wiley
Date: 06-2018
Primary productivity induced by iron and nitrogen in the Tasman Sea: An overview of the PINTS expedition
Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/MF13137
Abstract: The Tasman Sea and the adjacent subantarctic zone (SAZ) are economically important regions, where the parameters controlling the phytoplankton community composition and carbon fixation are not yet fully resolved. Contrasting nutrient distributions, as well as phytoplankton biomass, bio ersity and productivity were observed between the North Tasman Sea and the SAZ. In situ photosynthetic efficiency (FV/FM), dissolved and particulate nutrients, iron biological uptake, and nitrogen and carbon fixation were used to determine the factor-limiting phytoplankton growth and productivity in the North Tasman Sea and the SAZ. Highly productive cyanobacteria dominated the North Tasman Sea. High atmospheric nitrogen fixation and low nitrate dissolved concentrations indicated that non-diazotroph phytoplankton are nitrogen limited. Deck-board incubations also suggested that, at depth, iron could limit eukaryotes, but not cyanobacteria in that region. In the SAZ, the phytoplankton community was dominated by a bloom of haptophytes. The low productivity in the SAZ was mainly explained by light limitation, but nitrogen, silicic acid as well as iron were all depleted to the extent that they could become co-limiting. This study illustrates the challenge associated with identification of the limiting nutrient, as it varied between phytoplankton groups, depths and sites.
Pelagic forage fish distribution in a dynamic shelf ecosystem – Thermal demands and zooplankton prey distribution
Publisher: Elsevier BV
Date: 02-2020
Defining marine bacterioplankton community assembly rules by contrasting the importance of environmental determinants and biotic interactions
Publisher: Wiley
Date: 06-02-2023
Abstract: Bacterioplankton communities govern marine productivity and biogeochemical cycling, yet drivers of bacterioplankton assembly remain unclear. Here, we contrast the relative contribution of deterministic processes (environmental factors and biotic interactions) in driving temporal dynamics of bacterioplankton ersity at three different oceanographic time series locations, spanning 15° of latitude, which are each characterized by different environmental conditions and varying degrees of seasonality. Monthly surface s les (5.5 years) were analysed using 16S rRNA licon sequencing. The high‐ and mid‐latitude sites of Maria Island and Port Hacking were characterized by high and intermediate levels of environmental heterogeneity, respectively, with both alpha ersity (72% 24% of total variation) and beta ersity (32% 30%) patterns within bacterioplankton assemblages explained by day length, ammonium, and mixed layer depth. In contrast, North Stradbroke Island, a sub‐tropical location where environmental conditions are less variable, interspecific interactions were of increased importance in structuring bacterioplankton ersity (alpha: 33% beta: 26%) with environment only contributing 11% and 13% to predicting ersity, respectively. Our results demonstrate that bacterioplankton ersity is the result of both deterministic environmental and biotic processes and that the importance of these different deterministic processes varies, potential in response to environmental heterogeneity.
Zooplankton trophic niches respond to different water types of the western Tasman Sea: A stable isotope analysis
Publisher: Elsevier BV
Date: 10-2015
Sydney Harbour: What we do and do not know about a highly diverse estuary
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/MF15159
Abstract: Sydney Harbour is a global hotspot for marine and estuarine ersity. Despite its social, economic and biological value, the available knowledge has not previously been reviewed or synthesised. We systematically reviewed the published literature and consulted experts to establish our current understanding of the Harbour’s natural systems, identify knowledge gaps, and compare Sydney Harbour to other major estuaries worldwide. Of the 110 studies in our review, 81 focussed on ecology or biology, six on the chemistry, 10 on geology and 11 on oceanography. Subtidal rocky reef habitats were the most studied, with a focus on habitat forming macroalgae. In total 586 fish species have been recorded from the Harbour, which is high relative to other major estuaries worldwide. There has been a lack of process studies, and an almost complete absence of substantial time series that constrains our capacity to identify trends, environmental thresholds or major drivers of biotic interactions. We also highlight a lack of knowledge on the ecological functioning of Sydney Harbour, including studies on microbial communities. A sound understanding of the complexity, connectivity and dynamics underlying ecosystem functioning will allow further advances in management for the Harbour and for similarly modified estuaries around the world.
Evaluating vertical migration behavior of harmful raphidophytes in the Delaware Inland Bays utilizing quantitative real-time PCR
Publisher: Inter-Research Science Center
Date: 2005
DOI: 10.3354/AME040121
Heterogeneity in the photoprotective capacity of three Antarctic diatoms during short-term changes in salinity and temperature
Publisher: Springer Science and Business Media LLC
Date: 28-01-2011
Drift in ocean currents impacts intergenerational microbial exposure to temperature
Publisher: Proceedings of the National Academy of Sciences
Date: 02-05-2016
Abstract: Our current understanding of how marine biota are adapted to magnitudes, trends, and temporal patterns of variability in sea-surface temperature has arisen from examining long-term records at key ocean locations. However, floating plankton have a different perception of their habitat because they drift in ocean currents. Here we show that upper ocean microbes can be advected up to 3,500 km in latitude in 500 d, and that their operational temperatures exceed the in situ Eulerian temperature range by up to 10 °C, even in locations with strong seasonality. This result revises the present view of thermal exposure in the upper ocean, and provides a new framework for investigating climate change impacts on planktonic organisms.
Primary Production, an Index of Climate Change in the Ocean: Satellite-Based Estimates over Two Decades
Publisher: MDPI AG
Date: 03-03-2020
DOI: 10.3390/RS12050826
Abstract: Primary production by marine phytoplankton is one of the largest fluxes of carbon on our planet. In the past few decades, considerable progress has been made in estimating global primary production at high spatial and temporal scales by combining in situ measurements of primary production with remote-sensing observations of phytoplankton biomass. One of the major challenges in this approach lies in the assignment of the appropriate model parameters that define the photosynthetic response of phytoplankton to the light field. In the present study, a global database of in situ measurements of photosynthesis versus irradiance (P-I) parameters and a 20-year record of climate quality satellite observations were used to assess global primary production and its variability with seasons and locations as well as between years. In addition, the sensitivity of the computed primary production to potential changes in the photosynthetic response of phytoplankton cells under changing environmental conditions was investigated. Global annual primary production varied from 38.8 to 42.1 Gt C yr − 1 over the period of 1998–2018. Inter-annual changes in global primary production did not follow a linear trend, and regional differences in the magnitude and direction of change in primary production were observed. Trends in primary production followed directly from changes in chlorophyll-a and were related to changes in the physico-chemical conditions of the water column due to inter-annual and multidecadal climate oscillations. Moreover, the sensitivity analysis in which P-I parameters were adjusted by ±1 standard deviation showed the importance of accurately assigning photosynthetic parameters in global and regional calculations of primary production. The assimilation number of the P-I curve showed strong relationships with environmental variables such as temperature and had a practically one-to-one relationship with the magnitude of change in primary production. In the future, such empirical relationships could potentially be used for a more dynamic assignment of photosynthetic rates in the estimation of global primary production. Relationships between the initial slope of the P-I curve and environmental variables were more elusive.
Sydney Harbour: A review of anthropogenic impacts on the biodiversity and ecosystem function of one of the world's largest natural harbours
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/MF15157
Abstract: Sydney Harbour is a hotspot for ersity. However, as with estuaries worldwide, its ersity and functioning faces increasing threats from urbanisation. This is the first synthesis of threats and impacts in Sydney Harbour. In total 200 studies were reviewed: 109 focussed on contamination, 58 on habitat modification, 11 addressed non-indigenous species (NIS) and eight investigated fisheries. Metal concentrations in sediments and seaweeds are among the highest recorded worldwide and organic contamination can also be high. Contamination is associated with increased abundances of opportunistic species, and changes in benthic community structure. The Harbour is also heavily invaded, but invaders’ ecological and economic impacts are poorly quantified. Communities within Sydney Harbour are significantly affected by extensive physical modification, with artificial structures supporting more NIS and lower ersity than their natural equivalents. We know little about the effects of fishing on the Harbour’s ecology, and although ocean warming along Sydney is among the fastest in the world, we know little about how the ecosystem will respond to warming. The interactive and cumulative effects of stressors on ecosystem functioning and services in the Harbour are largely unknown. Sustainable management of this iconic natural system requires that knowledge gaps are addressed and translated into coherent environmental plans.
Impact of nitrogen availability upon the electron requirement for carbon fixation in Australian coastal phytoplankton communities
Publisher: Wiley
Date: 25-04-2018
DOI: 10.1002/LNO.10814
Assessment of Microzooplankton Grazing on Heterosigma akashiwo Using a Species- Specific Approach Combining Quantitative Real-Time PCR (QPCR) and Dilution Methods
Publisher: Springer Science and Business Media LLC
Date: 04-07-2007
DOI: 10.1007/S00248-007-9263-9
Abstract: Delaware's Inland Bays (DIB) are subject to numerous mixed blooms of harmful raphidophytes each year, and Heterosigma akashiwo is one of the consistently occurring species. Often, Chattonella subsalsa, C. cf. verruculosa, and Fibrocapsa japonica co-occur with H. akashiwo, indicating a dynamic consortium of raphidophyte species. In this study, microzooplankton grazing pressure was assessed as a top-down control mechanism on H. akashiwo populations in mixed communities. Quantitative real-time polymerase chain reaction (QPCR) with species-specific primers and probes were used in conjunction with the dilution method to assess grazing pressure on H. akashiwo and other raphidophytes. As a comparison, we measured changes in chlorophyll a (chl a) to determine whole community growth and mortality caused by grazing. We detected grazing on H akashiwo using QPCR in s les where chl a analyses indicated little or no grazing on the total phytoplankton community. Overall, specific microzooplankton grazing pressure on H akashiwo ranged from 0.88 to 1.88 day(-1) at various sites. Experiments conducted on larger sympatric raphidophytes (C. subsalsa, C. cf. verruculosa and F japonica) demonstrated no significant microzooplankton grazing on these species. Grazing pressure on H akashiwo may provide a competitive advantage to other raphidophytes such as Chattonella spp. that are too large to be consumed at high rates by microzooplankton and help to shape the dynamics of this harmful algal bloom consortium. Our results show that QPCR can be used in conjunction with the dilution method for evaluation of microzooplankton grazing pressure on specific phytoplankton species within a mixed community.
Sources and biogeochemical cycling of particulate selenium in the San Francisco Bay estuary
Publisher: Elsevier BV
Date: 05-2006
Toxicological characterization of Fukuyoa paulensis (Dinophyceae) from temperate Australia
Publisher: Wiley
Date: 16-10-2019
DOI: 10.1111/PRE.12349
Demography and interannual variability of salp swarms (Thalia democratica)
Publisher: Springer Science and Business Media LLC
Date: 15-09-2014
Long-term changes in temperate Australian coastal waters: Implications for phytoplankton
Publisher: Inter-Research Science Center
Date: 18-11-2009
DOI: 10.3354/MEPS08297
The role of 44-methylgambierone in ciguatera fish poisoning: Acute toxicity, production by marine microalgae and its potential as a biomarker for Gambierdiscus spp.
Publisher: Elsevier BV
Date: 07-2020
Rapid reductions in population size drive evolutionary divergence in diatoms
Publisher: Cold Spring Harbor Laboratory
Date: 27-09-2022
DOI: 10.1101/2022.09.25.509407
Abstract: Unicellular photosynthetic marine microbes, or phytoplankton, make up the base of marine food webs and drive global nutrient cycles. Despite their key roles in ecology and biogeochemistry, we have a limited understanding of how the basic features of their demographics along with dynamic environments affect trait evolution. A key feature of diatom ecology is frequent extreme reductions in population size, both as part of their bloom-and-bust growth dynamics, and as a result of living within ocean currents. Here, we use experimental evolution to understand which metabolic pathways and functions readily ersify in diatom populations following population bottleneck events. We subjected replicate populations of six genetically distinct diatom strains to population bottlenecks and then subsequently allowed them to evolve as large populations in the absence of environmental change. Phylogenies and global expression of orthologs were generally strain-specific, indicating that vertical (inherited) evolutionary constraints largely determine the occupation of specific locations in the transcriptional landscape (i.e. tran-scape). Following bottlenecks and subsequent evolution as large populations, transcriptional networks of most populations returned to those of the ancestral population. However, at least one replicate population per lineage migrated in the tran-scape, demonstrating that evolutionary changes in gene expression patterns and transcriptional relationships can be driven by population bottlenecks even in the absence of environmental change. Importantly, the orthologs dominating transcriptional ersification resided in common, central metabolic pathways. These data advance our understanding of constraints and patterns of transcriptional relationships underlying trait evolution in microbes that drive global food webs and elemental cycles.
Variation of phytoplankton functional groups modulated by hydraulic controls in Hongze Lake, China
Publisher: Springer Science and Business Media LLC
Date: 16-07-2015
DOI: 10.1007/S11356-015-4830-Y
Abstract: Hongze Lake is a large, shallow, polymictic, eutrophic lake in the eastern China. Phytoplankton functional groups in this lake were investigated from March 2011 to February 2013, and a comparison was made between the eastern, western, and northern regions. The lake shows strong fluctuations in water level caused by monsoon rains and regular hydraulic controls. By application of the phytoplankton functional group approach, this study aims to investigate the spatial and temporal dynamics and analyze their influencing factors. Altogether, 18 functional groups of phytoplankton were identified, encompassing 187 species. In order to seek the best variable describing the phytoplankton functional group distribution, 14 of the groups were analyzed in detail using redundancy analysis. Due to the turbid condition of the lake, the dominant functional groups were those tolerant of low light. The predominant functional groups in the annual succession were D (Cyclotella spp. and Synedra acus), T (Planctonema lauterbornii), P (Fragilaria crotonensis), X1 (Chlorella vulgaris and Chlorella pyrenoidosa), C (Cyclotella meneghiniana and Cyclotella ocellata), and Y (Cryptomonas erosa). An opposite relationship between water level and the biomass of predominant groups was observed in the present study. Water level fluctuations, caused by monsoonal climate and artificial drawdown, were significant factors influencing phytoplankton succession in Hongze Lake, since they alter the hydrological conditions and influence light and nutrient availability. The clearly demonstrated factors, which significantly influence phytoplankton dynamics in Hongze Lake, will help government manage the large shallow lakes with frequent water level fluctuations.
A new diatom species P. hallegraeffii sp. nov. belonging to the toxic genus Pseudo-nitzschia (Bacillariophyceae) from the East Australian Current
Publisher: Public Library of Science (PLoS)
Date: 12-04-2018
Modelling the impact of phytoplankton cell size and abundance on inherent optical properties (IOPs) and a remotely sensed chlorophyll-a product
Publisher: Elsevier BV
Date: 2021
Nutrient uplift in a cyclonic eddy increases diversity, primary productivity and iron demand of microbial communities relative to a western boundary current
Publisher: PeerJ
Date: 25-04-2016
DOI: 10.7717/PEERJ.1973
Abstract: The intensification of western boundary currents in the global ocean will potentially influence meso-scale eddy generation, and redistribute microbes and their associated ecological and biogeochemical functions. To understand eddy-induced changes in microbial community composition as well as how they control growth, we targeted the East Australian Current (EAC) region to s le microbes in a cyclonic (cold-core) eddy (CCE) and the adjacent EAC. Phototrophic and diazotrophic microbes were more erse (2–10 times greater Shannon index) in the CCE relative to the EAC, and the cell size distribution in the CCE was dominated (67%) by larger micro-plankton $(\\geq 20\\lrm{\\mu }\\mathrm{m})$, as opposed to pico- and nano-sized cells in the EAC. Nutrient addition experiments determined that nitrogen was the principal nutrient limiting growth in the EAC, while iron was a secondary limiting nutrient in the CCE. Among the diazotrophic community, heterotrophic NifH gene sequences dominated in the EAC and were attributable to members of the gamma-, beta-, and delta-proteobacteria, while the CCE contained both phototrophic and heterotrophic diazotrophs, including Trichodesmium , UCYN-A and gamma-proteobacteria. Daily s ling of incubation bottles following nutrient amendment captured a cascade of effects at the cellular, population and community level, indicating taxon-specific differences in the speed of response of microbes to nutrient supply. Nitrogen addition to the CCE community increased picoeukaryote chlorophyll a quotas within 24 h, suggesting that nutrient uplift by eddies causes a ‘greening’ effect as well as an increase in phytoplankton biomass. After three days in both the EAC and CCE, diatoms increased in abundance with macronutrient (N, P, Si) and iron amendment, whereas haptophytes and phototrophic dinoflagellates declined. Our results indicate that cyclonic eddies increase delivery of nitrogen to the upper ocean to potentially mitigate the negative consequences of increased stratification due to ocean warming, but also increase the biological demand for iron that is necessary to sustain the growth of large-celled phototrophs and potentially support the ersity of diazotrophs over longer time-scales.
Defining marine bacterioplankton community assembly rules by contrasting the importance of environmental determinants and biotic interactions
Publisher: Cold Spring Harbor Laboratory
Date: 04-05-2022
DOI: 10.1101/2022.05.02.490371
Abstract: Bacterioplankton communities play major roles in governing marine productivity and biogeochemical cycling, yet what drives the relative influence of the types of deterministic ecological processes which result in ersity patterns remains unclear. Here we examine how differing deterministic processes (environmental factors and biotic interactions) drive temporal dynamics of bacterioplankton ersity at three different oceanographic time-series locations, spanning 15 degrees of latitude, which are each characterized by different environmental conditions and varying degrees of seasonality. Monthly surface s les, collected over a period of 5.5 years, were analyzed using 16S rRNA licon sequencing. The high and mid-latitude sites of Maria Island and Port Hacking were characterized by high and intermediate levels of environmental heterogeneity respectively, with both alpha (local) ersity (72 % and 24 % of total variation) and beta ersity (32 % and 30 %) patterns within bacterioplankton assemblages primarily explained by environmental determinants, including day length, ammonium, and mixed layer depth. In contrast, at North Stradbroke Island, a sub-tropical location where environmental conditions are less seasonally variable, interspecific interactions were of increased importance in structuring bacterioplankton ersity (alpha ersity: 33 % beta ersity: 26 %) with environment only contributing 11 and 13 % to predicting ersity, respectively. Our results demonstrate that bacterioplankton ersity is the result of both deterministic environmental and biotic processes and that the importance of these different deterministic processes varies, potential in response to environmental heterogeneity. Marine bacterioplankton drives important biological processes, including the cycling of key nutrients or fixing atmospheric carbon. Therefore, to predict future climate scenarios its critical to model these communities accurately. Processes that drive bacterioplankton ersity patterns in the oceans however remain unresolved, with most studies focusing on deterministic environmental drivers, ie temperature or available inorganic nutrients. Biotic deterministic processes including interactions among in iduals are also important for structuring ersity patterns, however, this is rarely included to predict bacterioplankton communities. We develop an approach for determining the relative contribution of environmental and potential biotic interactions that structure marine bacterioplankton at three series at different latitudes. Environmental factors best predicted temporal trends in bacterioplankton ersity at the two high latitude time series, while biotic influence was most apparent at the low latitude time series. Our results suggest environmental heterogeneity is an important attribute driving the contribution of varying deterministic influence of bacterioplankton ersity.
Selenium in San Francisco Bay zooplankton: Potential effects of hydrodynamics and food web interactions
Publisher: Springer Science and Business Media LLC
Date: 08-2003
DOI: 10.1007/BF02803354
Comparative study of selenium requirements of three phytoplankton species: Gymnodinium catenatum, Alexandrium minutum (Dinophyta) and Chaetoceros cf. tenuissimus (Bacillariophyta)
Publisher: Oxford University Press (OUP)
Date: 06-1999
Application of ‘omics’ approaches to microbial oceanography
Publisher: Springer International Publishing
Date: 2017
Shaping up for stress: Physiological flexibility is key to survivorship in a habitat-forming macroalga
Publisher: Elsevier BV
Date: 12-2018
DOI: 10.1016/J.JPLPH.2018.10.005
Abstract: Organisms from all domains of life can have highly variable morphologies, with this plasticity suggested to increase fitness and survivability under stressful conditions. Predicting how organisms will adapt to environmental change requires an understanding of how variable morphologies perform under environmental stress. Morphological plasticity has been documented within marine macroalgae inhabiting environmental gradients, however the functional consequences of this variation has been rarely tested. In this study, form-function was assessed in the habitat-forming, intertidal macroalga Hormosira banksii. Morphological variation was quantified on two spatial scales (tidal gradient versus latitudinal gradient) and the performance tested (relative water content and photosynthetic efficiency) of morphological variants during heat and desiccation stress. At regional scales, in iduals at the warm distributional edge were overall smaller in size, and had smaller vesicles (higher surface area to volume ratio SA:VOL) than those from central populations. At local scales, in iduals high on the shore were generally shorter and had larger vesicles than those low on the shore. Vesicle morphology (SA:VOL) was found to predict relative water content and photosynthetic performance during desiccation and rehydration. Differences in SA:VOL of vesicles between heights on the shore may reflect water requirements needed to maintain tissue hydration for photosynthesis during low tide. Warm-edge populations showed increased thermal sensitivity as indicated by decreased photosynthetic yield of PSII and delays in recovery after desiccation. Sensitivities to higher temperatures amongst warm-edge populations are potentially due to smaller fluctuations in regional temperatures as well as their morphology. This study provides a mechanistic understanding of the morphological variation among H. banksii populations. It suggests that H. banksii has a high degree of morphological plasticity reflecting local climate, topography and environmental conditions, with this morphological variation having functional consequences. Morphological variation across local and regional scales will be important for resilience of this species to future climate warming.
Potential Invasion of Microorganisms and Pathogens via ‘Interior Hull Fouling’: Biofilms Inside Ballast Water Tanks
Publisher: Springer Science and Business Media LLC
Date: 11-2005
Iron-limitation and high light stress on phytoplankton populations from the Australian Sub-Antarctic Zone (SAZ)
Publisher: Elsevier BV
Date: 11-2011
Decontamination of water by excimer UV radiation
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 08-2002
Diel variation of chlorophyll-a fluorescence, phytoplankton pigments and productivity in the Sub-Antarctic and Polar Front Zones south of Tasmania, Australia
Publisher: Elsevier BV
Date: 11-2011
Warmer more acidic conditions cause decreased productivity and calcification in subtropical coral reef sediment-dwelling calcifiers
Publisher: Wiley
Date: 24-05-2011
Characterisation of Two Toxic Gambierdiscus spp. (Gonyaulacales, Dinophyceae) from the Great Barrier Reef (Australia): G. lewisii sp. nov. and G. holmesii sp. nov.
Publisher: Elsevier BV
Date: 12-2019
DOI: 10.1016/J.PROTIS.2019.125699
Abstract: Ciguatera fish poisoning (CFP) is a human illness caused via consumption of seafood contaminated with neurotoxins produced by some species from the epiphytic dinoflagellate genus Gambierdiscus. In this study, we describe two new species of Gambierdiscus isolated from Heron Island in the Southern Great Barrier Reef, Queensland, Australia. These new species were analysed using light microscopy, scanning electron microscopy, and phylogenetic analyses of nuclear encoded ribosomal ITS, SSU as well as D1-D3 and D8-D10 of the LSU gene regions. Gambierdiscus lewisii sp. nov. (Po, 3', 0a, 7″, 6c,? s, 5‴, 0p, 2'‴) is distinguished by its strong reticulate-foveate ornamentation and is genetically distinct from its sister species, G. pacificus. Gambierdiscus holmesii sp. nov. (Po, 3', 0a, 7″, 6c, 6s?, 5‴, 0p, 2'‴) is morphologically distinct from the genetically similar species G. silvae because of a strongly ventrally displaced apical pore complex and a characteristic fold at the anterior edge of the sulcus. Both G. lewisii and G. holmesii produce putative Maitotoxin-(44-Methylgambierone) and compounds which show ciguatoxin and maitotoxin-like activities. Identification of two new Gambierdiscus species will enable us to more accurately assess the risk of CFP in Australia and internationally.
Climate variability drives plankton community composition changes: The 2010-2011 El Niño to la Niña transition around Australia
Publisher: Oxford University Press (OUP)
Date: 09-2014
Characterising primary productivity measurements across a dynamic western boundary current region
Publisher: Elsevier BV
Date: 06-2015
Growth and biomass stimulation of the toxic dinoflagellate Gymnodinium catenatum (Graham) by dissolved organic substances
Publisher: Elsevier BV
Date: 03-1999
Subtropical zooplankton assemblage promotes the harmful cyanobacterium Cylindrospermopsis raciborskii in a mesocosm experiment
Publisher: Oxford University Press (OUP)
Date: 31-10-2014
Photosynthesis-irradiance parameters of marine phytoplankton: synthesis of a global data set
Publisher: Copernicus GmbH
Date: 07-06-2017
DOI: 10.5194/ESSD-2017-40
Abstract: Abstract. The photosynthetic performance of marine phytoplankton varies in response to a variety of factors, environmental and taxonomic. One of the aims of the MArine primary Production: model Parameters from Space (MAPPS) project of the European Space Agency is to assemble a global database of photosynthesis-irradiance (P-E) parameters from a range of oceanographic regimes as an aid to examining the basin-scale variability in the photophysiological response of marine phytoplankton and to use this information to improve the assignment of P-E parameters in the estimation of global marine primary production using satellite data. The MAPPS P-E Database, which consists of over 5000 P-E experiments, provides information on the spatio-temporal variability in the two P-E parameters (the assimilation number, PmB, and the initial slope, αB, where the superscripts B indicate normalisation to concentration of chlorophyll) that are fundamental inputs for models (satellite-based and otherwise) of marine primary production that use chlorophyll as the state variable. Quality-control measures consisted of removing s les with abnormally-high parameter values and flags were added to denote whether the spectral quality of the incubator l was used to calculate a broad-band value of αB. The MAPPS database provides a photophysiological dataset that is unprecedented in number of observations and in spatial coverage. The database would be useful to a variety of research communities, including marine ecologists, biogeochemical modellers, remote-sensing scientists and algal physiologists. The compiled data are available at 0.1594/PANGAEA.874087 (Bouman et al., 2017).
Live cell analysis at sea reveals divergent thermal performance between photosynthetic ocean microbial eukaryote populations
Publisher: Springer Science and Business Media LLC
Date: 31-01-2019
New resource for population genetics studies on the Australasian intertidal brown alga, Hormosira banksii: isolation and characterization of 15 polymorphic microsatellite loci through next generation DNA sequencing
Publisher: Springer Science and Business Media LLC
Date: 30-11-2017
Dynamic variability of the phytoplankton electron requirement for carbon fixation in eastern Australian waters
Publisher: Elsevier BV
Date: 02-2020
Potential for adaptation in response to thermal stress in an intertidal macroalga
Publisher: Wiley
Date: 03-05-2013
DOI: 10.1111/JPY.12067
Abstract: Understanding responses of marine algae to changing ocean temperatures requires knowledge of the impacts of elevated temperatures and the likelihood of adaptation to thermal stress. The potential for rapid evolution of thermal tolerance is dependent on the levels of heritable genetic variation in response to thermal stress within a population. Here, we use a quantitative genetic breeding design to establish whether there is a heritable variation in thermal sensitivity in two populations of a habitat-forming intertidal macroalga, Hormosira banksii (Turner) Descaisne. Gametes from multiple parents were mixed and growth and photosynthetic performance were measured in the resulting embryos, which were incubated under control and elevated temperature (20°C and 28°C). Embryo growth was reduced at 28°C, but significant interactions between male genotype and temperature in one population indicated the presence of genetic variation in thermal sensitivity. Selection for more tolerant genotypes thus has the ability to result in the evolution of increased thermal tolerance. Furthermore, genetic correlations between embryos grown in the two temperatures were positive, indicating that those genotypes that performed well in elevated temperature also performed well in control temperature. Chlorophyll a fluorescence measurements showed a marked decrease in maximum quantum yield of photosystem II (PSII) under elevated temperature. There was an increase in the proportion of energy directed to photoinhibition (nonregulated nonphotochemical quenching) and a concomitant decrease in energy used to drive photochemistry and xanthophyll cycling (regulated nonphotochemical quenching). However, PSII performance between genotypes was similar, suggesting that thermal sensitivity is related to processes other than photosynthesis.
Performance of Fast Repetition Rate fluorometry based estimates of primary productivity in coastal waters
Publisher: Elsevier BV
Date: 11-2014
Food Web Pathway Determines How Selenium Affects Aquatic Ecosystems: A San Francisco Bay Case Study
Publisher: American Chemical Society (ACS)
Date: 03-08-2004
DOI: 10.1021/ES0499647
Abstract: Chemical contaminants disrupt ecosystems, but specific effects may be under-appreciated when poorly known processes such as uptake mechanisms, uptake via diet, food preferences, and food web dynamics are influential. Here we show that a combination of food web structure and the physiology of trace element accumulation explain why some species in San Francisco Bay are threatened by a relatively low level of selenium contamination and some are not. Bivalves and crustacean zooplankton form the base of two dominant food webs in estuaries. The dominant bivalve Potamocorbula amurensis has a 10-fold slower rate constant of loss for selenium than do common crustaceans such as copepods and the mysid Neomysis mercedis (rate constant of loss, ke = 0.025, 0.155, and 0.25 d(-1), respectively). The result is much higher selenium concentrations in the bivalve than in the crustaceans. Stable isotope analyses show that this difference is propagated up the respective food webs in San Francisco Bay. Several predators of bivalves have tissue concentrations of selenium that exceed thresholds thought to be associated with teratogenesis or reproductive failure (liver Se >15 microg g(-1) dry weight). Deformities typical of selenium-induced teratogenesis were observed in one of these species. Concentrations of selenium in tissues of predators of zooplankton are less than the thresholds. Basic physiological and ecological processes can drive wide differences in exposure and effects among species, but such processes are rarely considered in traditional evaluations of contaminant impacts.
The cyanobacterium cylindrospermopsis raciborskii is facilitated by copepod selective grazing
Publisher: Elsevier BV
Date: 10-2013
Vertical migration of the toxic dinoflagellate Gymnodinium catenatum under different concentrations of nutrients and humic substances in culture
Publisher: Elsevier BV
Date: 12-2006
Dynamics of Prochlorococcus and Synechococcus at Station ALOHA Revealed through Flow Cytometry and High-Resolution Vertical Sampling
Publisher: Frontiers Media SA
Date: 27-11-2017
Temperature variability interacts with mean temperature to influence the predictability of microbial phenotypes.
Publisher: Wiley
Date: 20-07-2022
DOI: 10.1111/GCB.16330
Abstract: Despite their relatively high thermal optima ( T opt ), tropical taxa may be particularly vulnerable to a rising baseline and increased temperature variation because they live in relatively stable temperatures closer to their T opt . We examined how microbial eukaryotes with differing thermal histories responded to temperature fluctuations of different litudes (0 control, ±2, ±4°C) around mean temperatures below or above their T opt . Cosmopolitan dinoflagellates were selected based on their distinct thermal traits and included two species of the same genus (tropical and temperate Coolia spp.), and two strains of the same species maintained at different temperatures for generations (tropical Amphidinium massartii control temperature and high temperature, CT and HT, respectively). There was a universal decline in population growth rate under temperature fluctuations, but strains with narrower thermal niche breadth (temperate Coolia and HT) showed ~10% greater reduction in growth. At suboptimal mean temperatures, cells in the cool phase of the fluctuation stopped iding, fixed less carbon (C) and had enlarged cell volumes that scaled positively with elemental C, N, and P and C:Chlorophyll‐ a . However, at a supra‐optimal mean temperature, fixed C was directed away from cell ision and novel trait combinations developed, leading to greater phenotypic ersity. At the molecular level, heat‐shock proteins, and chaperones, in addition to transcripts involving genome rearrangements, were upregulated in CT and HT during the warm phase of the supra‐optimal fluctuation (30 ± 4°C), a stress response indicating protection. In contrast, the tropical Coolia species upregulated major energy pathways in the warm phase of its supra‐optimal fluctuation (25 ± 4°C), indicating a broadscale shift in metabolism. Our results demonstrate ergent effects between taxa and that temporal variability in environmental conditions interacts with changes in the thermal mean to mediate microbial responses to global change, with implications for biogeochemical cycling.
Ocean urea fertilization for carbon credits poses high ecological risks
Publisher: Elsevier BV
Date: 06-2008
Thermal niche evolution of functional traits in a tropical marine phototroph
Publisher: Wiley
Date: 13-08-2018
DOI: 10.1111/JPY.12759
Abstract: Land-based plants and ocean-dwelling microbial phototrophs known as phytoplankton, are together responsible for almost all global primary production. Habitat warming associated with anthropogenic climate change has detrimentally impacted marine primary production, with the effects observed on regional and global scales. In contrast to slower-growing higher plants, there is considerable potential for phytoplankton to evolve rapidly with changing environmental conditions. The energetic constraints associated with adaptation in phytoplankton are not yet understood, but are central to forecasting how global biogeochemical cycles respond to contemporary ocean change. Here, we demonstrate a number of potential trade-offs associated with high-temperature adaptation in a tropical microbial eukaryote, Amphidinium massartii (dinoflagellate). Most notably, the population became high-temperature specialized (higher fitness within a narrower thermal envelope and higher thermal optimum), and had a greater nutrient requirement for carbon, nitrogen and phosphorus. Evidently, the energetic constraints associated with living at elevated temperature alter competiveness along other environmental gradients. While high-temperature adaptation led to an irreversible change in biochemical composition (i.e., an increase in fatty acid saturation), the mechanisms underpinning thermal evolution in phytoplankton remain unclear, and will be crucial to understanding whether the trade-offs observed here are species-specific or are representative of the evolutionary constraints in all phytoplankton.
Effect of phytoplankton community size structure on remote-sensing reflectance and chlorophyll a products
Publisher: Elsevier BV
Date: 11-2020
Iron associated with exopolymeric substances is highly bioavailable to oceanic phytoplankton
Publisher: Elsevier BV
Date: 07-2015
Potential microbial bioinvasions via ships’ ballast water, sediment, and biofilm
Publisher: Elsevier BV
Date: 2007
DOI: 10.1016/J.MARPOLBUL.2006.11.007
Abstract: A prominent vector of aquatic invasive species to coastal regions is the discharge of water, sediments, and biofilm from ships' ballast-water tanks. During eight years of studying ships arriving to the lower Chesapeake Bay, we developed an understanding of the mechanisms by which invasive microorganisms might arrive to the region via ships. Within a given ship, habitats included ballast water, unpumpable water and sediment (collectively known as residuals), and biofilms formed on internal surfaces of ballast-water tanks. We s led 69 vessels arriving from foreign and domestic ports, largely from Western Europe, the Mediterranean region, and the US East and Gulf coasts. All habitats contained bacteria and viruses. By extrapolating the measured concentration of a microbial metric to the estimated volume of ballast water, biofilm, or residual sediment and water within an average vessel, we calculated the potential total number of microorganisms contained by each habitat, thus creating a hierarchy of risk of delivery. The estimated concentration of microorganisms was greatest in ballast water>>sediment and water residuals>>biofilms. From these results, it is clear microorganisms may be transported within ships in a variety of ways. Using temperature tolerance as a measure of survivability and the temperature difference between ballast-water s les and the water into which the ballast water was discharged, we estimated 56% of microorganisms could survive in the lower Bay. Extrapolated delivery and survival of microorganisms to the Port of H ton Roads in lower Chesapeake Bay shows on the order of 10(20) microorganisms (6.8 x 10(19) viruses and 3.9 x 10(18) bacteria cells) are discharged annually to the region.
Uptake of dissolved organic selenides by marine phytoplankton
Publisher: Wiley
Date: 11-2001
Multitrait diversification in marine diatoms in constant and warmed environments
Publisher: Cold Spring Harbor Laboratory
Date: 10-04-2022
DOI: 10.1101/2022.04.08.487611
Abstract: Phytoplankton are photosynthetic marine microbes that affect food webs, nutrient cycles, and climate regulation. Their roles are determined by a correlated set of phytoplankton functional traits including cell size, chlorophyll content, and cellular composition. Here, we explore how interrelated trait values and correlations evolve. Because both chance events and natural selection contribute to phytoplankton trait evolution, we used population bottlenecks to ersify six genotypes of Thalassiosirid diatoms. We then evolved them in two environments where natural selection could act on this ersity. Interspecific variation and within-species evolution were visualized for nine traits and their correlations using reduced axes (a trait-scape). Shifts in both trait values and correlations, resulting in movement of evolving populations on the trait-scape, occurred in both environments, and were more frequent under environmental change. Which trait correlations evolved was strain-specific, but greater departures from ancestral trait correlations were associated with lower population growth rates. There was no single master trait that could be used to understand multitrait evolution. Instead, repeatable multitrait evolution occurred along a major axis of variation defined by several diatom functional traits and trait relationships. Because trait-scapes capture changes in trait correlations and values together, they offer an insightful way to study multitrait variation.
Local Scale Thermal Environment and Limited Gene Flow Indicates Vulnerability of Warm Edge Populations in a Habitat Forming Macroalga
Publisher: Frontiers Media SA
Date: 27-08-2020
Ocean acidification and warming alter photosynthesis and calcification of the symbiont-bearing foraminifera Marginopora vertebralis
Publisher: Springer Science and Business Media LLC
Date: 18-07-2014
High levels of heterogeneity in diazotroph diversity and activity within a putative hotspot for marine nitrogen fixation
Publisher: Springer Science and Business Media LLC
Date: 27-11-2015
Contrasting oceanographic conditions and phytoplankton communities on the east and west coasts of Australia
Publisher: Elsevier BV
Date: 03-2011
The effect of surface flooding on the physical-biogeochemical dynamics of a warm-core eddy off southeast Australia
Publisher: Elsevier BV
Date: 03-2011
Rapid photoprotection in sea-ice diatoms from the East Antarctic pack ice
Publisher: Wiley
Date: 05-2010
A database of chlorophyll a in Australian waters
Publisher: Springer Science and Business Media LLC
Date: 20-02-2018
Abstract: Chlorophyll a is the most commonly used indicator of phytoplankton biomass in the marine environment. It is relatively simple and cost effective to measure when compared to phytoplankton abundance and is thus routinely included in many surveys. Here we collate 173, 333 records of chlorophyll a collected since 1965 from Australian waters gathered from researchers on regular coastal monitoring surveys and ocean voyages into a single repository. This dataset includes the chlorophyll a values as measured from s les analysed using spectrophotometry, fluorometry and high performance liquid chromatography (HPLC). The Australian Chlorophyll a database is freely available through the Australian Ocean Data Network portal ( portal.aodn.org.au/ ). These data can be used in isolation as an index of phytoplankton biomass or in combination with other data to provide insight into water quality, ecosystem state, and relationships with other trophic levels such as zooplankton or fish.
Relative impact of seasonal and oceanographic drivers on surface chlorophyll a along a Western Boundary Current
Publisher: Elsevier BV
Date: 2014
Predictability of thermal fluctuations influences functional traits of a cosmopolitan marine diatom
Publisher: The Royal Society
Date: 27-04-2022
Abstract: Evolutionary theory predicts that organismal plasticity should evolve in environments that fluctuate regularly. However, in environments that fluctuate less predictably, plasticity may be constrained because environmental cues become less reliable for expressing the optimum phenotype. Here, we examine how the predictability of +5°C temperature fluctuations impacts the phenotype of the marine diatom Thalassiosira pseudonana . Thermal regimes were informed by temperatures experienced by microbes in an ocean simulation and featured regular or irregular temporal sequences of fluctuations that induced mild physiological stress. Physiological traits (growth, cell size, complexity and pigmentation) were quantified at the in idual cell level using flow cytometry. Changes in cellular complexity emerged as the first impact of predictability after only 8–11 days, followed by deleterious impacts on growth on days 13–16. Specifically, cells with a history of irregular fluctuation exposure exhibited a 50% reduction in growth compared with the stable reference environment, while growth was 3–18 times higher when fluctuations were regular. We observed no evidence of heat hardening (increasingly positive growth) with recurrent fluctuations. This study demonstrates that unpredictable temperature fluctuations impact this cosmopolitan diatom under ecologically relevant time frames, suggesting shifts in environmental stochasticity under a changing climate could have widespread consequences among ocean primary producers.
Light dependence of selenium uptake by phytoplankton and implications for predicting selenium incorporation into food webs
Publisher: Wiley
Date: 03-2004
Characterisation of water masses and phytoplankton nutrient limitation in the East Australian Current separation zone during spring 2008
Publisher: Elsevier BV
Date: 03-2011
Dinoflagellate cyst abundance is positively correlated to sediment organic carbon in Sydney Harbour and Botany Bay, NSW, Australia
Publisher: Springer Science and Business Media LLC
Date: 12-12-2018
DOI: 10.1007/S11356-017-0886-1
Abstract: There is growing public concern about the global expansion of harmful algal bloom species (HABs), with dinoflagellate microalgae comprising the major portion of the harmful taxa. These motile, unicellular organisms have a lifecycle involving sexual reproduction and resting cyst formation whereby cysts can germinate from sediments and 'seed' planktonic populations. Thus, investigation of dinoflagellate cyst (dinocyst) distribution in sediments can provide significant insights into HAB dynamics and contribute to indices of habitat quality. Species composition and abundance of dinocysts in relation to sediment characteristics were studied at 18 stations in two densely populated temperate Australian estuaries, Sydney Harbour (Parramatta River/Port Jackson PS) and Botany Bay (including Georges River GB). Eighteen dinocyst taxa were identified, dominated by Protoceratium reticulatum and Gonyaulax sp.1 in the PS estuary, together with Archaeperidinium minutum and Gonyaulax sp.1 in the GB estuary. Cysts of Alexandrium catenella, which is one of the causative species of paralytic shellfish poisoning (PSP), were also detected in both estuaries. Out of the measured sediment characteristics (TOC, Cd, Cr, Cu, Fe, Pb, Mn, Ni, Zn and polycyclic aromatic hydrocarbons), TOC was the parameter explaining most of the variation in dinocyst assemblages and was positively correlated to most of the heavy metals. Given the significant relationship between sediment TOC and dinocyst abundance and heavy metal concentrations, this study suggests that sediment TOC could be broadly used in risk management for potential development of algal blooms and sediment contamination in these estuaries.
Global toxicology, ecophysiology and population relationships of the chainforming PST dinoflagellate Gymnodinium catenatum
Publisher: Elsevier BV
Date: 02-2012
The central role of selenium in the biochemistry and ecology of the harmful pelagophyte, Aureococcus anophagefferens
Publisher: Springer Science and Business Media LLC
Date: 07-03-2013
Toxicology of gambierdiscus spp. (dinophyceae) from tropical and temperate Australian waters
Publisher: MDPI AG
Date: 2018
DOI: 10.3390/MD16010007
Diurnal photosynthetic response of the motile symbiotic benthic foraminiferan marginopora vertebralis
Publisher: Inter-Research Science Center
Date: 25-03-2013
DOI: 10.3354/MEPS10187
Active water transport in unicellular algae: where, why, and how
Publisher: Oxford University Press (OUP)
Date: 09-09-2014
DOI: 10.1093/JXB/ERU360
Abstract: The occurrence of active water transport (net transport against a free energy gradient) in photosynthetic organisms has been debated for several decades. Here, active water transport is considered in terms of its roles, where it is found, and the mechanisms by which it could occur. First there is a brief consideration of the possibility of active water transport into plant xylem in the generation of root pressure and the refilling of embolized xylem elements, and from an unsaturated atmosphere into terrestrial organisms living in habitats with limited availability of liquid water. There is then a more detailed consideration of volume and osmotic regulation in wall-less freshwater unicells, and the possibility of generation of buoyancy in marine phytoplankton such as large-celled diatoms. Calculations show that active water transport is a plausible mechanism to assist cells in upwards vertical movements, requires less energy than synthesis of low-density organic solutes, and potentially on a par with excluding certain ions from the vacuole.
State transitions and nonphotochemical quenching during a nutrient-induced fluorescence transient in phosphorus-starved Dunaliella tertiolecta
Publisher: Wiley
Date: 10-2008
DOI: 10.1111/J.1529-8817.2008.00585.X
Abstract: Assessments of nutrient-limitation in microalgae using chl a fluorescence have revealed that nitrogen and phosphorus depletion can be detected as a change in chl a fluorescence signal when nutrient-starved algae are resupplied with the limiting nutrient. This photokinetic phenomenon is known as a nutrient-induced fluorescence transient, or NIFT. Cultures of the unicellular marine chlorophyte Dunaliella tertiolecta Butcher were grown under phosphate starvation to investigate the photophysiological mechanism behind the NIFT response. A combination of low temperature (77 K) fluorescence, photosynthetic inhibitors, and nonphotochemical quenching analyses were used to determine that the NIFT response is associated with changes in energy distribution between PSI and PSII and light-stress-induced nonphotochemical quenching (NPQ). Previous studies point to state transitions as the likely mechanism behind the NIFT response however, our results show that state transitions are not solely responsible for this phenomenon. This study shows that an interaction of at least two physiological processes is involved in the rapid quenching of chl a fluorescence observed in P-starved D. tertiolecta: (1) state transitions to provide the nutrient-deficient cell with metabolic energy for inorganic phosphate (Pi )-uptake and (2) energy-dependent quenching to allow the nutrient-stressed cell to avoid photodamage from excess light energy during nutrient uptake.
A limited legacy effect of copper in marine biofilms
Publisher: Elsevier BV
Date: 08-2016
DOI: 10.1016/J.MARPOLBUL.2016.06.011
Abstract: The effects of confounding by temporal factors remains understudied in pollution ecology. For ex le, there is little understanding of how disturbance history affects the development of assemblages. To begin addressing this gap in knowledge, marine biofilms were subjected to temporally-variable regimes of copper exposure and depuration. It was expected that the physical and biological structure of the biofilms would vary in response to copper regime. Biofilms were examined by inductively coupled plasma optical emission spectrometry, chlorophyll-a fluorescence and field spectrometry and it was found that (1) concentrations of copper were higher in those biofilms exposed to copper, (2) concentrations of copper remain high in biofilms after the source of copper is removed, and (3) exposure to and depuration from copper might have comparable effects on the photosynthetic microbial assemblages in biofilms. The persistence of copper in biofilms after depuration reinforces the need for consideration of temporal factors in ecology.
Photosynthesis-irradiance parameters of marine phytoplankton: Synthesis of a global data set
Publisher: Copernicus GmbH
Date: 06-02-2018
Abstract: Abstract. The photosynthetic performance of marine phytoplankton varies in response to a variety of factors, environmental and taxonomic. One of the aims of the MArine primary Production: model Parameters from Space (MAPPS) project of the European Space Agency is to assemble a global database of photosynthesis–irradiance (P-E) parameters from a range of oceanographic regimes as an aid to examining the basin-scale variability in the photophysiological response of marine phytoplankton and to use this information to improve the assignment of P-E parameters in the estimation of global marine primary production using satellite data. The MAPPS P-E database, which consists of over 5000 P-E experiments, provides information on the spatio-temporal variability in the two P-E parameters (the assimilation number, PmB, and the initial slope, αB, where the superscripts B indicate normalisation to concentration of chlorophyll) that are fundamental inputs for models (satellite-based and otherwise) of marine primary production that use chlorophyll as the state variable. Quality-control measures consisted of removing s les with abnormally high parameter values and flags were added to denote whether the spectral quality of the incubator l was used to calculate a broad-band value of αB. The MAPPS database provides a photophysiological data set that is unprecedented in number of observations and in spatial coverage. The database will be useful to a variety of research communities, including marine ecologists, biogeochemical modellers, remote-sensing scientists and algal physiologists. The compiled data are available at 0.1594/PANGAEA.874087 (Bouman et al., 2017).
Thermal Performance Curves of Functional Traits Aid Understanding of Thermally Induced Changes in Diatom-Mediated Biogeochemical Fluxes
Publisher: Frontiers Media SA
Date: 05-04-2016
First report of the potentially toxic marine diatom Pseudo-nitzschia simulans (Bacillariophyceae) from the East Australian Current
Publisher: Wiley
Date: 24-03-2020
DOI: 10.1111/PRE.12421
Local thermal adaptation and limited gene flow constrain future climate responses of a marine ecosystem engineer
Publisher: Wiley
Date: 25-01-2020
DOI: 10.1111/EVA.12909
Assessment of Microzooplankton Grazing on Heterosigma akashiwo Using a Species- Specific Approach Combining Quantitative Real-Time PCR (QPCR) and Dilution Methods
Publisher: Springer Science and Business Media LLC
Date: 26-03-2008
Taxon-specific responses of Southern Ocean diatoms to Fe enrichment revealed by synchrotron radiation FTIR microspectroscopy
Publisher: Copernicus GmbH
Date: 20-10-2014
Abstract: Abstract. Photosynthesis by marine diatoms contributes substantially to global biogeochemical cycling and ecosystem productivity. It is widely accepted that diatoms are extremely sensitive to changes in Fe availability, with numerous in situ experiments demonstrating rapid growth and increased export of elements (e.g. C, Si and Fe) from surface waters as a result of Fe addition. Less is known about the effects of Fe enrichment on the phenotypes of diatoms, such as associated changes in nutritional value – furthermore, data on taxon-specific responses are almost non-existent. Enhanced supply of nutrient-rich waters along the coast of the subantarctic Kerguelen Island provide a valuable opportunity to examine the responses of phytoplankton to natural Fe enrichment. Here we demonstrate the use of synchrotron radiation Fourier Transform Infrared (SR-FTIR) microspectroscopy to analyse changes in the macromolecular composition of diatoms collected along the coast and plateau of Kerguelen Island, Southern Ocean. SR-FTIR microspectroscopy enabled the analysis of in idual diatom cells from mixed communities of field-collected s les, thereby providing insight into in situ taxon-specific responses in relation to changes in Fe availability. Phenotypic responses were taxon-specific in terms of intraspecific variability and changes in proteins, amino acids, phosphorylated molecules, silicate/silicic acid and carbohydrates. In contrast to some previous studies, silicate/silicic acid levels increased under Fe enrichment, in conjunction with increases in carbohydrate stores. The highly abundant taxon Fragilariopsis kerguelensis displayed a higher level of phenotypic plasticity than Pseudo-nitzschia spp., while analysis of the data pooled across all measured taxa showed different patterns in macromolecular composition compared to those for in idual taxon. This study demonstrates that taxon-specific responses to Fe enrichment may not always be accurately reflected by bulk community measurements, highlighting the need for further research into taxon-specific phenotypic responses of phytoplankton to environmental change.
Evolution, Microbes, and Changing Ocean Conditions
Publisher: Annual Reviews
Date: 03-01-2020
DOI: 10.1146/ANNUREV-MARINE-010318-095311
Abstract: 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.
Contrasting phytoplankton composition and primary productivity in multiple mesoscale eddies along the East Australian coast
Publisher: Elsevier BV
Date: 03-2023
Colorimetric detection of caspase 3 activity and reactive oxygen derivatives: Potential early indicators of thermal stress in corals
Publisher: Hindawi Limited
Date: 2016
DOI: 10.1155/2016/6825949
Abstract: There is an urgent need to develop and implement rapid assessments of coral health to allow effective adaptive management in response to coastal development and global change. There is now increasing evidence that activation of caspase-dependent apoptosis plays a key role during coral bleaching and subsequent mortality. In this study, a “clinical” approach was used to assess coral health by measuring the activity of caspase 3 using a commercial kit. This method was first applied while inducing thermal bleaching in two coral species, Acropora millepora and Pocillopora damicornis . The latter species was then chosen to undergo further studies combining the detection of oxidative stress-related compounds (catalase activity and glutathione concentrations) as well as caspase activity during both stress and recovery phases. Zooxanthellae photosystem II (PSII) efficiency and cell density were measured in parallel to assess symbiont health. Our results demonstrate that the increased caspase 3 activity in the coral host could be detected before observing any significant decrease in the photochemical efficiency of PSII in the algal symbionts and/or their expulsion from the host. This study highlights the potential of host caspase 3 and reactive oxygen species scavenging activities as early indicators of stress in in idual coral colonies.
Information content of in situ and remotely sensed chlorophyll-a: Learning from size-structured phytoplankton model
Publisher: Elsevier BV
Date: 07-2018
Transport of the Harmful Bloom Alga Aureococcus anophagefferens by Oceangoing Ships and Coastal Boats
Publisher: American Society for Microbiology
Date: 11-2004
DOI: 10.1128/AEM.70.11.6495-6500.2004
Abstract: It is well established that cyst-forming phytoplankton species are transported in ships' ballast tanks. However, there is increasing evidence that other phytoplankton species which do not encyst are also capable of surviving ballast transit. These species have alternative modes of nutrition (hetero- or mixotrophy) and/or are able to survive long-term darkness. In our studies of no-ballast-on-board vessels arriving in the Great Lakes, we tested for the presence of the harmful algal bloom species Aureococcus anophagefferens (brown tide) in residual (i.e., unpumpable) ballast water using methods based on the PCR. During 2001, the brown tide organism was detected in 7 of 18 ballast water tanks in commercial ships following transit from foreign ports. Furthermore, it was detected after 10 days of ballast tank confinement during a vessel transit in the Great Lakes, a significant result given the large disparity between the salinity tolerance for active growth of Aureococcus ( ppt) and the low salinity of the residual ballast water (∼2 ppt). We also investigated the potential for smaller, recreational vessels to transport and distribute Aureococcus . During the summer of 2002, 11 trailered boats from the inland bays of Delaware and coastal bays of Maryland were s led. Brown tide was detected in the bilge water in the bottoms of eight boats, as well as in one live-well s le. Commercial ships and small recreational boats are therefore implicated as potential vectors for long-distance transport and local-scale dispersal of Aureococcus .
Impact of light limitation on seagrasses
Publisher: Elsevier BV
Date: 11-2007
Photophysiological responses of fragilariopsis cylindrus (bacillariophyceae) to nitrogen depletion at two temperatures
Publisher: Wiley
Date: 20-12-2012
DOI: 10.1111/J.1529-8817.2011.01107.X
Abstract: The photosynthetic efficiency and photoprotective capacity of the sea-ice diatom, Fragilariopsis cylindrus (Grunow) W. Krieg., grown in a matrix of nitrogen repletion and depletion at two different temperatures (-1°C and +6°C) was investigated. Temperature showed no significant effect on photosynthetic efficiency or photoprotection in F. cylindrus. Cultures under nitrogen depletion showed enhanced photoprotective capacity with an increase in nonphotochemical quenching (NPQ) when compared with nitrogen-replete cultures. This phenomenon was achieved at no apparent cost to the photosynthetic efficiency of PSII (FV /FM ). Nitrogen depletion yielded a partially reduced electron transport chain in which maximum fluorescence (FM ) could only be obtained by adding 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). reoxidation curves showed the presence of QB nonreducing PSII centers under nitrogen depletion. Fast induction curves (FICs) and electron transport rates (ETRs) revealed slowing of the electrons transferred from the primary (QA ) to the secondary (QB ) quinone electron acceptors of PSII. The data presented show that nitrogen depletion in F. cylindrus leads to the formation of QB nonreducing PSII centers within the photosystem. On a physiological level, the formation of QB nonreducing PSII centers in F. cylindrus provides the cell with protection against photoinhibition by facilitating the rapid induction of NPQ. This strategy provides an important ecological advantage, especially during the Antarctic spring, maintaining photosynthetic efficiency under high light and nutrient-limiting conditions.
Dynamics and short-term survival of toxic cyanobacteria species in ballast water from NOBOB vessels transiting the Great Lakes—implications for HAB invasions
Publisher: Elsevier BV
Date: 08-2007
Physical oceanographic processes influence bio-optical properties in the Tasman Sea
Publisher: Elsevier BV
Date: 04-2016
Surface immuno-functionalisation for the capture and detection of vibrio species in the marine environment: A new management tool for industrial facilities
Publisher: Public Library of Science (PLoS)
Date: 13-10-2014
Polychaete Richness and Abundance Enhanced in Anthropogenically Modified Estuaries Despite High Concentrations of Toxic Contaminants
Publisher: Public Library of Science (PLoS)
Date: 30-09-2013
Intraspecific variation in the selenium requirement of different geographic strains of the toxic dinoflagellate Gymnodinium catenatum
Publisher: Oxford University Press (OUP)
Date: 03-2000
Phosphate-inducible poly-hydroxy butyrate production dynamics in CO2 supplemented upscaled cultivation of engineered Phaeodactylum tricornutum
Publisher: Springer Science and Business Media LLC
Date: 09-07-2022
DOI: 10.1007/S10811-022-02795-Y
Abstract: Diatoms such as Phaeodactylum tricornutum are emerging as sustainable alternatives to traditional eukaryotic microbial cell factories. In order to facilitate a viable process for production of heterologous metabolites, a rational genetic design specifically tailored to metabolic requirements as well as optimised culture conditions are required. In this study we investigated the effect of constitutive and inducible expression of the heterologous poly-3-hydroxybutyrate (PHB) pathway in P. tricornutum using non-integrative episomes in 3 different configurations. Constitutive expression led to downregulation of at least one in idual gene out of three ( phaA , phaB and phaC ) and was outperformed by inducible expression. To further asses and optimise the dynamics of PHB accumulation driven by the inducible alkaline phosphatase 1 promoter, we upscaled the production to lab-scale bioreactors and tested the effect of supplemented CO 2 on biomass and PHB accumulation. While ambient CO 2 cultivation resulted in a maximum PHB yield of 2.3% cell dry weight (CDW) on day 11, under elevated CO 2 concentrations PHB yield peaked at 1.7% CDW on day 8, coincident with PHB titres at 27.9 mg L −1 that were approximately threefold higher than ambient CO 2 . With other more valuable bio-products in mind, these results highlight the importance of the genetic design as well as substrate availability to supply additional reduction equivalents to boost biomass accumulation and relieve potential enzymatic bottlenecks for improved product accumulation.
Effects of secondarily-treated sewage effluent on the early life-history stages of two species of brown macroalgae: Hormosira banksii and Durvillaea potatorum
Publisher: Springer Science and Business Media LLC
Date: 06-1995
DOI: 10.1007/BF00350691
Partitioning of fungal assemblages across different marine habitats
Publisher: Wiley
Date: 16-02-2016
Abstract: Fungi are a highly erse group of microbes that fundamentally influence the biogeochemistry of the biosphere, but we currently know little about the ersity and distribution of fungi in aquatic habitats. Here we describe shifts in marine fungal community composition across different marine habitats, using targeted pyrosequencing of the fungal Internal Transcribed Spacer (ITS) region. Our results demonstrate strong partitioning of fungal community composition between estuarine, coastal and oceanic s les, with each habitat hosting discrete communities that are controlled by patterns in salinity, temperature, oxygen and nutrients. Whereas estuarine habitats comprised a significant proportion of fungal groups often found in terrestrial habitats, the open ocean sites were dominated by previously unidentified groups. The patterns observed here indicate that fungi are potentially a significant, although largely overlooked, feature of the ocean's microbiota, but greater efforts to characterize marine species are required before the full ecological and biogeochemical importance of marine fungi can be ascertained.
Microbial tropicalization driven by a strengthening western ocean boundary current
Publisher: Wiley
Date: 27-07-2020
DOI: 10.1111/GCB.15257
Key drivers of seasonal plankton dynamics in cyclonic and anticyclonic eddies off East Australia
Publisher: Frontiers Media SA
Date: 30-08-2016
Microenvironmental changes support evidence of photosynthesis and calcification inhibition in Halimeda under ocean acidification and warming
Publisher: Springer Science and Business Media LLC
Date: 08-09-2012
Improved quantitative real-time PCR assays for enumeration of harmful algal species in field samples using an exogenous DNA reference standard
Publisher: Wiley
Date: 18-08-2005
Microbial consortia increase thermal tolerance of corals
Publisher: Springer Science and Business Media LLC
Date: 06-06-2012
Photoprotection of sea-ice microalgal communities from the east antarctic pack ice
Publisher: Wiley
Date: 13-01-2011
DOI: 10.1111/J.1529-8817.2010.00944.X
Abstract: All photosynthetic organisms endeavor to balance energy supply with demand. For sea-ice diatoms, as with all marine photoautotrophs, light is the most important factor for determining growth and carbon-fixation rates. Light varies from extremely low to often relatively high irradiances within the sea-ice environment, meaning that sea-ice algae require moderate physiological plasticity that is necessary for rapid light acclimation and photoprotection. This study investigated photoprotective mechanisms employed by bottom Antarctic sea-ice algae in response to relatively high irradiances to understand how they acclimate to the environmental conditions presented during early spring, as the light climate begins to intensify and snow and sea-ice thinning commences. The sea-ice microalgae displayed high photosynthetic plasticity to increased irradiance, with a rapid decline in photochemical efficiency that was completely reversible when placed under low light. Similarly, the photoprotective xanthophyll pigment diatoxanthin (Dt) was immediately activated but reversed during recovery under low light. The xanthophyll inhibitor dithiothreitol (DTT) and state transition inhibitor sodium fluoride (NaF) were used in under-ice in situ incubations and revealed that nonphotochemical quenching (NPQ) via xanthophyll-cycle activation was the preferred method for light acclimation and photoprotection by bottom sea-ice algae. This study showed that bottom sea-ice algae from the east Antarctic possess a high level of plasticity in their light-acclimation capabilities and identified the xanthophyll cycle as a critical mechanism in photoprotection and the preferred means by which sea-ice diatoms regulate energy flow to PSII.
Phenotypic plasticity of southern ocean diatoms: Key to success in the sea ice habitat?
Publisher: Public Library of Science (PLoS)
Date: 21-11-2013
Genetic differentiation between estuarine and open coast ecotypes of a dominant ecosystem engineer
Publisher: CSIRO Publishing
Date: 2019
DOI: 10.1071/MF17392
Abstract: 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 bio ersity on both rocky shores and estuarine habitats, yet we know little about the processes that structure populations. Herein we characterise the genetic ersity 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 ersity and gene flow in this important ecosystem engineer will enhance the ability to manage, conserve and restore this key species into the future.
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