Natural succession of microalgal communities during the cold-water season and the impact of increased solar irradiance on sea ice algae

The winter season in polar and sub-polar areas is commonly described as a dormant phase for microalgae, especially in the water column, although the sea ice is a habitat for diverse and active communities. However, these areas are subject to changing environmental conditions due to global warming and changes in ultraviolet radiation. This thesis describes the natural succession of microalgal communities in the water column and sea ice during the cold-water winter season. Results show that the cold-water season is dynamic with various microalgal communities and their variable photosynthetic activity in the water column and sea ice. Although microalgal biomass is relatively low throughout the cold-water season, especially in the water column, natural succession during the cold-water season can be divided into five different groups based on microalgal community composition. Similar to the water column, algal succession in the sea ice begins with low biomass and domination of various flagellates. Thereafter the biomass in the ice increases and the community shifts to being diatom and dinoflagellate dominated. In late spring, sea ice algae communities differ between the ice layers from the top to the bottom ice, and the highest biomass in the bottom ice layer (dominated by colonial pennate diatoms). However, the contribution of released dominant sea ice algae to the water column community is not significant, and the spring bloom community is largely formed by pelagic species of the early open-water season. This thesis also describes the effect of enhanced solar irradiance on the microalgal community at various ice depths.We studied the effects of enhanced solar irradiance (including PAR and UVR) on the microalgal community at various depths of the spring ice during a three-week experimental in situ study. Results show that the largest effect of enhanced solar irradiance occurs in the top 10-cm layer of ice, but even beneath this layer the diminishing amount of irradiance and change in light quality increase the photosynthetic activity and change the community composition of the sea ice algae. Exposure to ultraviolet radiation also increases the concentration of mycosporine-like amino acids (MAA) and the variety of MAA compounds in the sea ice algae. Global warming is likely to result in thinner ice and could thus lead to changes in sea ice algae community structure in the Baltic Sea area, i.e. changes in the sea-ice pennate diatom community. The altered community and population dynamics in the sea ice may decrease the productivity and change the functioning of the system in the sea ice-pelagic coupling and bentho-pelagic coupling.Korkeilla leveysasteilla kasviplanktonbiomassa on alhainen talvikaudella ja kasviplanktonyhteisöjen ajatellaan olevan lepotilassa. Alueilla, joissa muodostuu merijäätä, merijää muodostaa elinympäristön monimuotoiselle eliöyhteisölle, johon kuuluu viruksia, bakteereita sekä yksisoluisia mikroleviä. Väitöskirjassa kuvataan mikroleväyhteisön kehittyminen sekä vesipatsaassa että merijäässä Suomen lounaisrannikolla lokakuun alusta toukokuun loppuun asti. Itämerellä jäätalvien pituus on lyhentynyt viime vuosikymmenien aikana. Lisäksi jää ja jään päällä oleva lumikerros ohentuvat, jos ilmasto on aikaisempia vuosikymmeniä lämpimämpi. Jään mikrolevät altistuvat myös suuremmalle määrälle auringon valoa (sis. näkyvän valon ja ultraviolettisäteilyn). Merijäässä mikrolevät eivät pysty liikkumaan samalla tavalla kuin vesipatsaassa, mutta mikrolevät voivat suojautua haitalliselta ultraviolettisäteilyltä tuottamalla MAA-yhdisteitä (mycosporine-like amino acids). Tässä väitöskirjassa esitetään lisääntyneen näkyvän valon sekä ultraviolettisäteilyn vaikutus merijääleväyhteisöjen biomassaan, lajimonimuotoisuuteen, fotosynteettiseen aktiivisuuteen ja MAA-yhdisteiden monimuotoisuuteen ja pitoisuuksiin jään eri kerroksissa

Mamiellophyceae shift in seasonal predominance in the Baltic Sea

The green algae Mamiellophyceae are a group of marine picoeukaryotes. We studied the succession of Mamiellophyceae in the Baltic Sea water column and ice from autumn to summer, using the hypervariable V4 region of the 18S ribosomal RNA (18S rRNA) gene. We show that species of Mamiellophyceae shift in seasonal predominance and that different species characterize sea ice, under-ice water, and the water column in the Baltic Sea.peerReviewe

Phases of microalgal succession in sea ice and the water column in the Baltic Sea from autumn to spring

The phytoplankton biomass in the Baltic Sea is low during the cold-water season (October to May) compared to the warm-water season(June to September). However, the sea ice is a habitat for diverse assemblages in polar and subpolar areas. These areas, including the Baltic Sea, are subject to changing environmental conditions due to global warming, and temporal and spatial studies are required to understand changes in the processes the organisms are involved in. We delineated microalgal succession in the northern Baltic Sea during the cold-water season using a weekly collected data set. Microscopy results together with molecular methods showed that 5 microbial groups could be distinguished: the sea-ice microalgal assemblage and 4 phytoplankton assemblages(fall, winter, under-ice water and spring). Based on cell enumeration, the microalgal biomass in the water column remained low until the end of the ice-covered season and was dominated by small flagellates and dinoflagellates. The young-ice assemblage in January resembled the water-column assemblage, but indicated a partly selective species-concentrating mechanism during ice formation due to lower species richness in ice than in the water column. Biomass of microalgae increased in the ice and water column during the March to May period, and the assemblage changed from flagellate-dominated to diatom-and dinoflagellate-dominated. The result that the spring phytoplankton, based on species and biomass, formed a separate as semblage indicates that sea-ice algae did not contribute to the spring bloom phytoplankton assemblage.Peer reviewe

Autumn to spring microbial community in the northern Baltic Sea : temporal variability in bacterial, viral and nanoflagellate abundance during the cold-water season

Marine microbial communities undergo drastic changes during the seasonal cycle in high latitude seas. Despite the dominance of microbial biomass in the oceans, comprehensive studies on the seasonal changes of microbial plankton during the complete winter period are lacking. To study the seasonal variation in abundance of the microbial community, water samples were collected weekly in the Northern Baltic Sea from October to May. During ice cover from mid-January to April, samples from the sea ice and the underlying water were taken in addition to the water column samples. Abundances of bacteria, virus-like particles, nanoflagellates, and chlorophyll a concentrations were measured from sea ice, under-ice water, and the water column, and examined in relation to environmental conditions. All studied organisms had clear seasonal changes in abundance, and the sea-ice microbial community had an independent wintertime development compared to the water column. Bacteria were observed to have a key role in the biotic interactions in both ice and the water column, and the dormant period during the cold-water months (October–May) was limited to before ice formation. Our results provide the first insights into the temporal dynamics of bacteria and viruses during the whole cold-water season (October–May) in coastal high latitude seas, and demonstrate that changes in the environmental conditions are likely to affect bacterial dynamics and have implications on trophic interactions

Regulation of insulin-like growth factor-II expression and its role in autocrine growth of human neuroblastoma cells

Insulin-like growth factor-II (IGF-II) is highly expressed in fetal tissues and may act as an autocrine growth factor during early embryogenesis. The SH-SY5Y human neuroblastoma cell line also expresses IGF-II and its receptors and responds to exogenous IGF-II with increased DNA synthesis, cell division, and neuritic outgrowth. For this study, we tested the hypothesis that IGF-II mediates autocrine growth of SH-SY5Y cells in serum-free media. SH-SY5Y cells plated at high densities proliferated in serum-free media, whereas sparsely plated cells did not. IGF-II mRNA levels increased within 24 hours of serum deprivation and were associated with increased immunoreactive IGF-II protein. Exogenous addition of IGF-II increased 3 H-TdR incorporation and cell number in a dose- and time-dependent fashion. By nuclear labelling experiments using 5-Bromo-2′ deoxyuridine (BrdU), we detected a twofold higher percentage of S phase nuclei after a 24-hour incubation in IGF-II. Treatment of SH-SY5Y cells with anti-IGF-II antibodies in serum-free media inhibited cell proliferation, and this inhibition was partially overcome by the addition of increasing concentrations of IGF-II. Collectively, our results indicate that IGF-II mediates an autocrine growth mechanism in SH-SY5Y cells that is associated with increased IGF-II expression. © 1993 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49884/1/1041550210_ftp.pd

Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

Contains fulltext : 172380.pdf (publisher's version ) (Open Access

The independent audit and professional ethics for accountants according to the Swedish Auditors Act

Several industrial scandals, especially those about Enron and WorldCom, have lead to an intense debate about the independent audit and the independent auditor. A substantial part of the auditor’s income originates from counselling, and therefore the role of the auditor may be seen as double, and the auditor’s objectivity may be questioned. In the year of 2002, a new Auditors Act was legislated in Sweden. In the 21 § of the act, a model based on principles was introduced, to test the auditor independence in every single case. The question is if the new Auditors Act better ensures an independent audit than the preceding Act did. After the collapse of Enron, the international work on the development of rules that better can guarantee the independent audit, has been intensified. Will the wording and effect of the Swedish Auditors Act stand, will the international progress on this area influence the interpretation of the Act, or will the Swedish legislator be forced to rewrite the Act? Three problems are discussed in this thesis; 1. How shall an independent audit be ensured?, 2 What kind of activity may the auditor exercise?, 3 How should the auditor’s activities be organised to ensure the independence? This thesis describes howthe role of the auditor and his independence is regulated today, partly by legislation, partly by self- regulation, both national and international. Different regulations are compared and differences and similarities are described. A number of specific problems that may influence the independence of the auditor, in relation to his clients, and a discussion about how these problems may be avoided, is presented

Spatial restrictions inadvertently doubled the carbon footprint of Norway's mackerel fishing fleet

The ocean is increasingly used for industry, energy and recreation or protected for conservation, resulting in increasing spatial restrictions for fisheries. Simultaneously, producing seafood with a low climate footprint is becoming increasingly important. Despite this, the effects of spatial restrictions on the emissions of fishing fleets are poorly known. In the Northeast Atlantic, the withdrawal of the United Kingdom from the EU (Brexit) meant that the UK regained autonomy in its Exclusive Economic Zone (EEZ). This suddenly imposed a spatial restriction for several foreign fishing fleets targeting Northeast Atlantic mackerel (Scomber scombrus). Here, we use this natural experiment and open fisheries data to investigate how Brexit affected the performance and emissions of the Norwegian mackerel fishery. As the fleet was excluded from fishing grounds in the UK, the catch per fishing trip almost halved, while the number of trips per vessel doubled. As a result, fuel use intensity (FUI) more than doubled from ∼0.08 to ∼0.18 L fuel per kg mackerel. We estimate that this shift required an additional 23 million liters of fuel per year, causing additional fuel costs of ∼€18 million annually and emitting an additional ∼72,000 tonnes CO2 per year. The policy change undid ∼15 years of improved fuel efficiency in Norwegian pelagic fisheries. These findings provide rare empirical evidence on how spatial restrictions can undermine progress towards decreasing greenhouse gas emissions in fisheries, highlighting the need to monitor and account for emissions in fisheries management and consider these trade-offs in marine spatial management. This work is funded by the Norwegian Research Council , project 326896 </p