Phytoplankton community succession and dynamics using optical approaches

The phytoplankton in coastal regions are responding to constant environmental changes, thus the use of proxies derived from in situ frequent time-series observations and validated from traditional microscopic or pigment methods can be a solution for detecting rapid responses of community dynamics and succession. In this study, we combined in situ high-frequency (every 30 min from May to September 2017) optical and hydrographic data from a moored buoy and weekly discrete samplings to track phytoplankton community dynamics and succession in Mausund Bank, a highly productive region of the coast of Norway. Three hydrographic regimes were observed: mixing period (MP) in spring, onset of stratification (transient period, TP) in summer and a stratified period (SP) in fall, with occasional strong winds that disrupted the surface stratification in the beginning of September. A bloom dominated by the diatom Skeletonema costatum was observed in the MP due to intense mixing and nutrient availability, while flagellates prevailed in nutrient-poor waters during the TP, followed by a bloom dominated by rhizosolenid diatoms (Proboscia alata and Guinardia delicatula), when stratification peaked. A mixed assemblage of diatoms (e.g. Pseudo-nitzschia), coccolithophores and dinoflagellates occurred during the SP, as strong winds reintroduced nutrients to surface waters. Through pigment (chemotaxonomy) and microscopic observations, we tested, for the first time in a coastal region, whether an ‘optical community index’ derived from in situ measurements of chlorophyll a fluorescence (Fchla) and optical particulate backscattering (bbp) is suitable to differentiate between diatom versus flagellate dominance. We found a negative relationship between Fchla:bbp and diatom:flagellate, contrary to previous observations, possibly because of the influence of non-algal contribution (e.g. zooplankton, fecal pellets and detritus) to the bbp pool in highly productive systems. This finding suggests that such relationship is not universal and that other parameters are needed to refine the optical community index in coastal regions

Klimatiltak i Klubben næringspark

Senja kommune regulerer planarbeidet for Klubben næringspark på Senja. Næringsparken er forbeholdt blågrønn næringsvirksomhet og så langt er det to aktører som har besluttet å etablere seg på området, herunder slakteri og bearbeidingsanlegg, og EPS-fabrikk. Videre er anlegg for videreforedling av biprodukter og biogassproduksjon øvrige aktøre som har vært nevnt i forbindelse med Klubben næringspark, men som foreløpig ikke har tatt beslutning om etablering. Formålet med prosjektet har vært å identifisere og evaluere synergier der uutnyttede material- og energistrømmer kan anvendes på tvers av aktørene i næringsparken, eller som utgangspunkt for å introdusere ny industriaktivitet. Kartleggingen av material- og energistrømmer har kulminert i en prioritert liste over klimatiltak, og det er gitt anbefalinger for videre arbeid. Det vurderes å være grunnlag for videre utredning av blant annet produksjon av marine organismer og utnyttelse av varme og CO2 i veksthus. Biogassproduksjon kan være en driver for sirkulære verdikjeder, og en videre utredning bør ses i sammenheng med øvrig planlagt aktivitet i næringsparken. Videre kan fiskefôrproduksjon være et interessant tilskudd til næringsparken som kan utredes nærmere.publishedVersio

Influence of Nitrogen Limitation on Lipid Accumulation and EPA and DHA Content in Four Marine Microalgae for Possible Use in Aquafeed

Microalgae are regarded as a promising alternative that can replace fishmeal and fish oil in aquaculture. Under N-limitation, many microalgae species change their carbon storage patterns in favor of neutral lipids (NLs) mainly in the form of triacylglycerol (TAG), but fatty acids in polar lipids (PL) are nutritionally more available for fish than those esterified into NLs. In the present study, the effect of N-limitation on the lipid content and fatty acid profiles in different lipid classes of Phaeodactylum tricornutum, Isochrysis aff. galbana clone T-Iso, Rhodomonas baltica, and Nannochloropsis oceanica were investigated. The microalgae cells were cultivated by two different methods, batch and semi-continuous culture, to create strong and moderate N-limitation, and this in turn will significantly affect the biomass and lipid productivity. All four species accumulated lipids mainly in the form of TAG, in response to strong nitrogen limitation. N. oceanica, however, accumulated 51% of the dry weight as lipid in moderate nitrogen limitation and up to 87% of the fatty acid was in TAG. Isochrysis aff. galbana clone T-Iso was the only species where the fraction of polyunsaturated fatty acid (PUFA), especially the fraction of docosahexaenoic acid (DHA), increased with increasing nitrogen limitation. Total lipid productivity showed no increase in batch culture although stronger nitrogen limitation led to lipid accumulation. P. tricornutum had the highest eicosapentaenoic acid (EPA) content, while N. oceanica showed the highest EPA productivity due to the high content of lipid. The highest DHA productivity was found in Isochrysis aff. galbana clone T-Iso from moderate N-limitation, mainly due to the high biomass productivity. Based on the results from the current study, N. oceanica and T-Iso are two promising microalgae strains ass long-term sustainable sources of n-3 long chain -PUFAs under moderate N-limitation. As shown in the present study, increased lipid content in microalgal cells due to strong N-limitation induction may not increase the lipid productivity because biomass production is usually reduced. Therefore, a combination of approaches such as metabolic engineering, conditioning and selection may be needed to further increase the n-3 LC-PUFA productivity without substantial loss of biomass

NordAqua, a Nordic Center of Excellence to develop an algae-based photosynthetic production platform

NordAqua is a multidisciplinary Nordic Center of Excellence funded by NordForsk Bioeconomy program (2017-2022). The research center promotes Blue Bioeconomy and endeavours to reform the use of natural resources in a environmentally sustainable way. In this short communication, we summarize particular outcomes of the consortium. The key research progress of NordAqua includes (1) improving of photosynthetisis, (2) developing novel photosynthetic cell factories that function in a "solar-driven direct CO2 capture to target bioproducts" mode, (3) promoting the diversity of Nordic cyanobacteria and algae as an abundant and resilient alternative for less sustainable forest biomass and for innovative production of biochemicals, and (4) improving the bio-based wastewater purification and nutrient recycling technologies to provide new tools for integrative circular economy platforms.Peer reviewe

NordAqua, a Nordic Center of Excellence to develop an algae-based photosynthetic production platform

NordAqua is a multidisciplinary Nordic Center of Excellence funded by NordForsk Bioeconomy program (2017-2022). The research center promotes Blue Bioeconomy and endeavours to reform the use of natural resources in a environmentally sustainable way. In this short communication, we summarize particular outcomes of the consortium. The key research progress of NordAqua includes (1) improving of photosynthetisis, (2) developing novel photosynthetic cell factories that function in a "solar-driven direct CO2 capture to target bioproducts" mode, (3) promoting the diversity of Nordic cyanobacteria and algae as an abundant and resilient alternative for less sustainable forest biomass and for innovative production of biochemicals, and (4) improving the bio-based wastewater purification and nutrient recycling technologies to provide new tools for integrative circular economy platforms.</p

Nuclear Magnetic Resonance spectroscopy of marine microalgae : Metabolic profiling and species discrimination from High-Resolution Magic Angle Spinning NMR analysis of whole-cell samples

Based on what is said about the background and structure, this thesis presents a discussion of the use of NMR spectroscopy as a tool for species discrimination and metabolic profiling of microalgae. The results of various analyses including NMR and statistics are evaluated from what is known from already established identification methods such as pigment chromatography and chemotaxonomy, and the chemical composition of microalgal cells. The main focus is on the application of HR MAS on whole cells, which means quick and easy sample preparation with no extraction involved and large information output in terms of metabolite composition in a single analysis run

Light and photosynthetic microalgae: A review of cellular- and molecular-scale optical processes

Light and its interaction with microalgae are essential concerns in the context of microalgae studies. The optical properties of microalgae have a great impact on the remote sensing ocean color, underwater light distribution and biomass accumulation, to mention some areas. A deep understanding of these processes requires knowledge on both the physical light interaction mechanisms with algae, and effects in cellular photophysiology and eventually primary production. Therefore, in this review we comprehensively explain the fundamental physical principles behind microalgae optical properties addressing the multidisciplinary microalgae community. We try to answer what happens with light in the microalgal cell on the cellular and molecular level, and explain the physical mechanisms of light absorption, scattering, fluorescence and diffraction. The current optical cell models that describe the absorbance and scattering properties of microalgae are compared and reviewed. The recent discoveries of the behavior of light in diatom frustules and coccolithophore coccoliths are represented, also showing the special role of these microalgae groups in terms of light interaction. Because microalgae and light are reciprocally interacting, we will briefly also view the photoacclimation and chromatic regulation associated with physical, metabolic and gene transcriptory changes. Finally, predictions and suggestions on the future research directions within oceanography, limnology, remote sensing and aqua culture are provided

Dynamic responses to silicon in Thalassiosira pseudonana - Identification, characterisation and classification of signature genes and their corresponding protein motifs

The diatom cell wall, or frustule, is a highly complex, three-dimensional structure consisting of nanopatterned silica as well as proteins and other organic components. While some key components have been identified, knowledge on frustule biosynthesis is still fragmented. The model diatom Thalassiosira pseudonana was subjected to silicon (Si) shift-up and shift-down situations. Cellular and molecular signatures, dynamic changes and co-regulated clusters representing the hallmarks of cellular and molecular responses to changing Si availabilities were characterised. Ten new proteins with silaffin-like motifs, two kinases and a novel family of putatively frustule-associated transmembrane proteins induced by Si shift-up with a possible role in frustule biosynthesis were identified. A separate cluster analysis performed on all significantly regulated silaffin-like proteins (SFLPs), as well as silaffin-like motifs, resulted in the classification of silaffins, cingulins and SFLPs into distinct clusters. A majority of the genes in the Si-responsive clusters are highly divergent, but positive selection does not seem to be the driver behind this variability. This study provides a high-resolution map over transcriptional responses to changes in Si availability in T. pseudonana. Hallmark Si-responsive genes are identified, characteristic motifs and domains are classified, and taxonomic and evolutionary implications outlined and discussed.publishedVersio

Klimatiltak i Klubben næringspark

Senja kommune regulerer planarbeidet for Klubben næringspark på Senja. Næringsparken er forbeholdt blågrønn næringsvirksomhet og så langt er det to aktører som har besluttet å etablere seg på området, herunder slakteri og bearbeidingsanlegg, og EPS-fabrikk. Videre er anlegg for videreforedling av biprodukter og biogassproduksjon øvrige aktøre som har vært nevnt i forbindelse med Klubben næringspark, men som foreløpig ikke har tatt beslutning om etablering. Formålet med prosjektet har vært å identifisere og evaluere synergier der uutnyttede material- og energistrømmer kan anvendes på tvers av aktørene i næringsparken, eller som utgangspunkt for å introdusere ny industriaktivitet. Kartleggingen av material- og energistrømmer har kulminert i en prioritert liste over klimatiltak, og det er gitt anbefalinger for videre arbeid. Det vurderes å være grunnlag for videre utredning av blant annet produksjon av marine organismer og utnyttelse av varme og CO2 i veksthus. Biogassproduksjon kan være en driver for sirkulære verdikjeder, og en videre utredning bør ses i sammenheng med øvrig planlagt aktivitet i næringsparken. Videre kan fiskefôrproduksjon være et interessant tilskudd til næringsparken som kan utredes nærmere