Diatoms, dinoflagellates and their distinct effects on the structure and function of the bacterioplankton

Global warming is one of the most alarming pressures affecting marine ecosystems worldwide. One of the indirect effects of the increasing surface-water temperature is the change in phytoplankton community composition, shifting in some ecosystems from diatom predominance towards the dinoflagellate predominance or co-occurrence with diatoms during blooms. These distinct phytoplankton groups vary in the quality and/or quantity of the dissolved organic matter (DOM) they release, which may have contrasting effects on the associated bacterioplankton communities, in terms of structure and function, and also on the carbon flux passing through the microbial loop. The main objective of this thesis was to assess the effect of diatoms and dinoflagellates on shaping the bacterial community composition and dynamics in different ecosystems in which either one or both of these two groups dominate the phytoplankton bloom, such as the Baltic Sea and the Humboldt Current System (HCS) off Chile. This was achieved by conducting both experimental and field studies in these areas. Phytoplankton community composition and the stage of the bloom phase clearly affected to the bacterial community composition and dynamics in both ecosystems. Alphaproteobacteria, dominated by SAR11 and Rhodobacteraceae, was the most abundant bacterial class in all studies. The oligotrophic SAR11 dominated in pre-bloom conditions and was associated with dinoflagellates. In contrast, copiotrophic bacteria belonging to the classes Flavobacteriia, Gammaproteobacteria, Betaproteobacteria and the family Rhodobacteraceae (genera Loktanella, Planktotalea, Planktomarina and Amylibacter) were associated with diatom species such as Achnanthes taeniata, Chaetoceros spp., Skeletonema costatum and Thalassiosira levanderi in the Baltic Sea and with Thalassiosira spp. in the HCS. In addition, in the Baltic Sea, bacterial communities dominated by copiotrophs had higher bacterial production rates than in SAR11 dominated bacterial communities. Hence, the diatom-released DOM boosted the development of more productive bacterial communities during phytoplankton blooms. Further differences in the bacterial community composition were driven by the different salinities in these two ecosystems; Betaproteobacteria, Planctomycetes and Actinobacteria were more abundant in the brackish Baltic Sea than in the HCS. The results of this thesis highlight that the shift to the dinoflagellate dominance or co-occurrence with diatoms may affect the bacterial community composition and activity during bloom events. Certain diatom species promote the growth of copiotrophic bacteria, which contribute largely to high bacterial production rates and recycling of carbon. In contrast, the increase in dinoflagellate abundance associated with global warming may potentially change the pelagic remineralization of organic matter, which could reduce the carbon flux to higher trophic levels.Ilmaston lämpeneminen vaikuttaa meriekosysteemeihin maailmanlaajuisesti. Kasvavat pintalämpötilat muuttavat kasviplanktonyhteisöjen koostumusta ja tietyissä ekosysteemeissä kevätkukintaa dominoivat piilevät saattavat menettää osin tai kokonaan valta-asemansa panssarisiimaleville. Nämä kaksi kasviplanktonryhmää eroavat toisistaan niiden vapauttaman liuenneen eloperäisen aineen laadun ja/tai määrän suhteen vaikuttaen näiden ekosysteemien bakteeriyhteisöjen lajistoon ja toimintaan ja edelleen mikrobisilmukan kautta kulkevan hiilen määrään. Tämän työn päätavoitteena oli arvioida kokeellisesti sekä kenttätutkimuksin piilevien ja panssarisiimalevien vaikutusta bakteeriyhteisön rakenteeseen ja dynamiikkaan Itämeren ja Chilen rannikon (Humboldtin merivirran alue) ekosysteemeissä, joissa nämä leväryhmät, joko yhdessä tai erikseen, dominoivat kevätkukinnan kasviplanktonlajistoa. Kasviplanktonyhteisön lajisto ja kukinnan vaihe vaikuttivat selvästi bakteeriyhteisön rakenteeseen ja dynamiikkaan molemmissa tutkituista ekosysteemeistä. Alphaproteobakteerit, pääosin SAR11-kladiin ja Rhodobacteraceae-heimoon kuuluvat bakteerit, oli hallitseva bakteeriluokka kaikissa tutkimuksissa. Oligotrofiset SAR11-kladiin kuuluvat bakteerit olivat runsaslukuisa ennen kevätkukintaa sekä assosioituivat panssarisiimaleviin, kun taas kopiotrofisten flavo-, gammaproteo- ja betaproteobakteerien sekä Rhodobacteraceae-heimoon kuuluvien bakteerien (Loktanella, Planktotalea, Planktomarina ja Amylibacter suvut) runsaudet olivat suorassa yhteydessä tiettyihin piilevälajeihin kuten Achnanthes taeniata, Chaetoceros, Skeletonema costatum ja Thalassiosira levanderi -lajeihin Itämerellä sekä Thalassiosira -lajeihin Chilen rannikolla. Itämerellä havaittiin lisäksi, että piilevien vapauttama liuennut eloperäinen aines kiihdytti tuottavampien bakteeriyhteisöjen muodostumista kevätkukinnan aikana, mikä näkyi kopiotrofisten bakteerien dominoimien bakteeriyhteisöjen korkeampana tuotantona verrattuna SAR11-valtaisiin yhteisöihin. Myös suolaisuus vaikutti tutkittujen ekosysteemien bakteeriyhteisöjen välisiin eroihin; Betaproteobacteria, Planctomycetes ja Actinobacteria olivat yleisempiä murtovetisessä Itämeressä kuin Chilen rannikolla. Tässä työssä saatujen tulosten perusteella voidaan sanoa, että muutokset piilevien ja panssarisiimalevien määräsuhteissa kevätkukinnan aikana vaikuttavat hyvin todennäköisesti bakteeriyhteisön rakenteeseen ja toimintaan. Tietyt piilevälajit edistävät kopiotrofisten bakteerien kasvua, mikä näkyy korkeana bakteerituotantona ja indikoi tehokasta eloperäisen aineksen hajotusta. Panssarisiimalevien yleistyminen ilmastonmuutoksen myötä mahdollisesti heikentää tätä pelagiaalista hajotustoimintaa vähentäen ylemmille tuotantotasoille siirtyvää hiilen määrää

Phosphorylation of MAP Kinases crucially controls the response to environmental stress in Dunaliella viridis

The green unicellular microalga Dunaliella viridis has the ability to cope with a wide variety of environmental stressful conditions, such as thermal and osmotic shocks, high PAR, UV radiation and nitrogen deficiency. The lack of a rigid cell wall makes D. viridis an excellent model organism to study stress signaling in eukaryotic unicellular organisms. Mitogen-activated protein kinases (MAPKs) are highly conserved serine/threonine kinases that convert extracellular stimuli into a wide range of responses at both cellular and nuclear levels. In eukaryotic cells, MAPKs are involved in both cell proliferation and differentiation (ERK pathway) and stress responses (JNK and p38 pathways), through protein kinase cascades. Significantly lesser phosphorylation levels of ERK-like protein were observed in D. viridis cultures acclimated to high salinity (3-4 M NaCl). In contrast, JNK-like and p38-like proteins phosphorylation levels increased in stressed cells. Likewise, the efficacy of specific commercial inhibitors of the phosphorylation of ERK (PD98059), JNK (SP600125) and p38 (SB203580) revealed the importance of JNK-like proteins in the maintenance of cell viability, the highlighted participation of p38-like proteins and the non-direct implication of the ERK-like proteins in the acclimatization process. In summary, specific blockade of JNK- and p38-like cascades in stressed cells led to rapid cell death. The behavior of MAPK-like proteins in algae is not known in depth, so the analysis of their mechanism of action, as well as their function in this model microalga, will allow to estimate the fate of unicellular eukaryotic organisms in aquatic ecosystems subjected to environmental stress derived from the conditions prevailing within a framework of global climate change.Peer reviewe

Phosphorylation of MAP kinases crucially controls the response to environmental stress in Dunaliella viridis

El objetivo principal de este estudio fue analizar el papel que llevan a cabo las cascadas de las proteínas tipo MAPKs en la transducción de señales de estrés ambiental en el organismo modelo D. viridis. Se detectó la activación/desactivación y la función de las proteínas tipo MAPKs en este microalga adaptada a condiciones de alta salinidad, ante condiciones de hipersalinidad, alta irradiancia y UV.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Bacterioplankton dynamics driven by interannual and spatial variation in diatom and dinoflagellate spring bloom communities in the Baltic Sea

In parts of the Baltic Sea, the phytoplankton spring bloom communities, commonly dominated by diatoms, are shifting toward the co‐occurrence of diatoms and dinoflagellates. Although phytoplankton are known to shape the composition and function of associated bacterioplankton communities, the potential bacterial responses to such a decrease of diatoms are unknown. Here we explored the changes in bacterial communities and heterotrophic production during the spring bloom in four consecutive spring blooms across several sub‐basins of the Baltic Sea and related them to changes in environmental variables and in phytoplankton community structure. The taxonomic structure of bacterioplankton assemblages was partially explained by salinity and temperature but also linked to the phytoplankton community. Higher carbon biomass of the diatoms Achnanthes taeniata, Skeletonema marinoi, Thalassiosira levanderi, and Chaetoceros spp. was associated with more diverse bacterial communities dominated by copiotrophic bacteria (Flavobacteriia, Gammaproteobacteria, and Betaproteobacteria) and higher bacterial production. During dinoflagellate dominance, bacterial production was low and bacterial communities were dominated by Alphaproteobacteria, mainly SAR11. Our results suggest that increases in dinoflagellate abundance during the spring bloom will largely affect the structuring and functioning of the associated bacterial communities. This could decrease pelagic remineralization of organic matter and possibly affect the bacterial grazers communities.Academy of Finland | Ref. 292711Agencia Estatal de Investigación | Ref. RTI2018-099740-J-I00Walter ja Andrée de Nottbeckin Säätiö | Ref. 25916

European Union legislation on macroalgae products

Macroalgae-based products are increasing in demand also in Europe. In the European Union, each category of macroalgae-based products is regulated separately. We discuss EU legislation, including the law on medicinal products, foods including food supplements and food additives, feed and feed additives, cosmetics, packaging materials, fertilizers and biostimulants, as well as biofuels. Product safety and consumer protection are the priorities with any new products. Macroalgae products can be sold as traditional herbal medicines. The novel food regulation applies to macroalgae foods that have not previously been used as food, and organic macroalgae are a specific regulatory category. The maximum levels of heavy metals may be a barrier for macroalgae foods, feeds, and fertilizers. Getting health claims approved for foods based on macroalgae is demanding. In addition to the rules on products, the macroalgae business is strongly impacted by the elements of the general regulatory environment such as agricultural/aquacultural subsidies, maritime spatial planning and aquaculture licensing, public procurement criteria, tax schemes, and trade agreements.</p

European Union legislation on macroalgae products

Macroalgae-based products are increasing in demand also in Europe. In the European Union, each category of macroalgae-based products is regulated separately. We discuss EU legislation, including the law on medicinal products, foods including food supplements and food additives, feed and feed additives, cosmetics, packaging materials, fertilizers and biostimulants, as well as biofuels. Product safety and consumer protection are the priorities with any new products. Macroalgae products can be sold as traditional herbal medicines. The novel food regulation applies to macroalgae foods that have not previously been used as food, and organic macroalgae are a specific regulatory category. The maximum levels of heavy metals may be a barrier for macroalgae foods, feeds, and fertilizers. Getting health claims approved for foods based on macroalgae is demanding. In addition to the rules on products, the macroalgae business is strongly impacted by the elements of the general regulatory environment such as agricultural/aquacultural subsidies, maritime spatial planning and aquaculture licensing, public procurement criteria, tax schemes, and trade agreements

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Macroalgae production in Northern Europe : Business and government perspectives on how to regulate a novel blue bioeconomy

Macroalgae biomass production, understood as cultivation and harvesting, is a minor industry in Europe at present, but the sector is recognized as having substantial growth potential. Here, we framed the environmental license as a boundary object between business and authorities and investigated the details of macroalgal licensing procedures in seven Northern European countries (Finland, Estonia, Sweden, Germany, Norway, Iceland, and Scotland). We conducted surveys and interviews with macroalgae companies and licensing authorities to understand the challenges faced by both sides. Generally, macroalgae production in Northern European countries is regulated by environmental and water laws and is not included in maritime spatial plans. Private actors need to apply for an environmental, water and/or fishing permit to start operations in this sector, often with several authorities involved. The companies expressed their dissatisfaction with non-specific laws and burdensome licensing procedures that may delay or even prevent the start-up. The authorities highlighted the lack of scientific environmental risk assessments of macroalgae production and the need to resolve possible conflicts with other marine sectors. Companies need the license to access markets while authorities view the license as a tool to enforce environmental legislation. As a boundary object, the license is the result of correspondence and cooperation between companies and authorities. A one-step licensing procedure for macroalgae production should be applied to encourage this business and to facilitate the compliance of legislation. In addition, macroalgae related activities should be recognized in the national maritime spatial plans to facilitate long-term planning. Highlights • Producers and authorities are key players developing the macroalgae sector in Europe. • Companies demand a specific macroalgae regulatory framework. • Authorities require assessment of the environmental risks of macroalgae production. • The license can be viewed as a boundary object between macroalgae companies and authorities

European Union legislation on macroalgae products

Macroalgae-based products are increasing in demand also in Europe. In the European Union, each category of macroalgae-based products is regulated separately. We discuss EU legislation, including the law on medicinal products, foods including food supplements and food additives, feed and feed additives, cosmetics, packaging materials, fertilizers and biostimulants, as well as biofuels. Product safety and consumer protection are the priorities with any new products. Macroalgae products can be sold as traditional herbal medicines. The novel food regulation applies to macroalgae foods that have not previously been used as food, and organic macroalgae are a specific regulatory category. The maximum levels of heavy metals may be a barrier for macroalgae foods, feeds, and fertilizers. Getting health claims approved for foods based on macroalgae is demanding. In addition to the rules on products, the macroalgae business is strongly impacted by the elements of the general regulatory environment such as agricultural/aquacultural subsidies, maritime spatial planning and aquaculture licensing, public procurement criteria, tax schemes, and trade agreements