Cyanobacteria are widely distributed in marine, freshwater and terrestrial habitats. Some cyanobacterial genera can convert di-nitrogen gas (N2) to bioavailable ammonium, i.e. perform nitrogen (N) fixation, and are therefore of profound significance for N cycling. N fixation by summer blooms of cyanobacteria is one of the largest sources of new N for the Baltic Sea. This thesis investigated N fixation by cyanobacteria in the Baltic Sea and explored the fate of fixed N at different spatial and temporal scales. In Paper I, we measured cell-specific N fixation by Aphanizomenon sp. at 10 ºC, early in the season. Fixation rates were high and comparable to those in late summer, indicating that Aphanizomenon sp. is an important contributor to N fixation already in its early growth season. In Paper II, we studied fixation and release of N by Aphanizomenon sp. and found that about half of the fixed N was rapidly released and transferred to other species, including autotrophic and heterotrophic bacteria, diatoms and copepods. In Paper III, we followed the development of a cyanobacterial bloom and related changes in dissolved and particulate N pools in the upper mixed surface layer. The bloom-associated total N (TN) increase was mainly due to higher particulate organic N (PON) concentrations, but also to increases in dissolved organic nitrogen (DON). About half the PON-increase could be explained by the sum of N-fixing cyanobacteria, other phytoplankton (&gt;2µm) and zooplankton, indicating that production was stimulated by the N fixation. In Paper IV, we used a growth model based on measured photosynthesis–irradiance relationships to explore the production potential of Aphanizomenon sp. The model included data on irradiance, biomass, temperature and light attenuation (1999–2013). Until the bloom peak, the modelled production matched the measured biomass, indicating low production losses. Over the whole season, the modelled production could explain a substantial part of the summer TN increase, assuming that plausible losses (such as grazing or cell lysis) are retained within the upper mixed layer. Complementing the other data, we also investigated the nutrient content (Paper I) and varying cell width (Paper IV) of Aphanizomenon sp. By a combination of approaches, this thesis has contributed new information on cyanobacterial N fixation rates, the transfer of fixed N to other organisms in the food web and shown the potential for fixed N to stimulate summer primary and secondary production in the Baltic Sea. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.</p>

Beobachtete und über parametns1erte Beziehungen berechnete Windreibungs-koeffizienten werden für die Zeit eines Sturms, der in der Zeit zwischen dem 08.07.96 und 11.07.96 an der Ostseeküste tobte, verglichen. Die innerhalb der ufernahen Zone aus Windprofildaten ermittelten Reibungskoeffizienten lassen sich mit weniger als 20% Fehler auch über vorliegende parametrisierten Beziehungen aus einer standardisierten Windgeschwindigkeitsmessung berechnen. / A comparison between observed and calculated wind drag coefficients were investigated during a storm with wind speeds up to 20 m/s at the Baltic Sea coast between 3th July, 1996 and 1 lth July, 1996. The drag coefficient which was determined from observed wind speeds from wind profile measurements can also be predicted on behalf of parameterised relations with a random error less then 20%.

Through complex metabolic interactions aquatic microbial life is essential as a driver of ecosystem functions and hence a prerequisite for sustaining plant and animal life in the sea and on Earth. Despite its ecological importance, infor­mation on the complexity of microbial functions and how these are related to environmental conditions is limited. Due to climate change and eutrophication, marine areas facing oxygen depletion are increasing and predicted to continue to do so in the future. Vertically steep oxygen gradients are particularly pronoun­ced in the Baltic Sea. In this thesis, therefore, the ecosystem functions of micro­bial communities were investigated, using metagenomics, to understand how they were distributed along the steep oxygen gradient at the Landsort Deep, the deepest point of the Baltic Sea. Furthermore, microbial communities from the Lands­ort Deep transect were compared to microbial communities of other marine environments to establish whether the environment at this site resulted in a characteristic community. To reveal what microbial community functions and taxa were active in the anoxic sediment a metatranscriptomic approach was used. Results showed a marked effect of the coupled environmental parameters dissolved oxygen, salinity and temperature on distribution of taxa and par­ti­cularly community functions. Microbial communities showed functional capa­cities consistent with a copiotrophic life-style dependent on organic ma­terial sinking through the water column. The eutrophic condition with high organic load was further reflected in the metatranscriptome of the anoxic sedi­ment com­munity, which indicated active carbon mineralisation through ana­erobic hetero­trophic-autotrophic community synergism. New putative linkages between nitro­gen and- sulphur metabolisms were identified at anoxic depths. Further­more, viable Cyanobacteria in the anoxic sediment was evident from the tran­script analyses as another reflection of marine snow. High abundance and expres­­sion of integron integrases were identified as a charac­teristic feature of the Lands­ort Deep communities, and may provide these communities with a mech­an­ism for short-term-adaptation to environmental change. In summary, this thesis clearly documents what impact eutrophication and oxygen depletion have on microbial community functions. Furthermore, it specifically advances the mechanistic insight into microbial processes in anoxic deep-water sediment at both genomic and transcriptional level. Given the predicted progress of oxygen depletion in marine and brackish environments, this work advances information necessary to estimate effects on marine and in particular brackish ecosystem functions where anoxic conditions prevail. / Mikroorganismer är essentiella för fungerande ekosystemfunktioner i akvatiska miljöer och därmed en förutsättning för övrigt växt- och djurliv på vår planet. Trots deras ekologiska nyckelroll är kunskapen om mikroorganismernas funk­tion och komplexitet samt hur dessa är relaterade till miljön begränsad. På grund av eutrofiering och klimatförändringar har marina områden som lider av syrebrist ökat och en ytterligare utbredning av marina och bräckta områden med syrebrist är predicerad i framtiden. Stora områden av Östersjön kännetecknas av vertikala syregradienter med syresatt ytvatten och anoxiskt bottenvatten. I denna avhandling undersöktes därför med metagenomik hur mikrobiella ekosystems funktioner var utbredda längs den vertikala syregradienten i Östersjöns djupaste del, Landsortsdjupet. Dessutom jämfördes de mikrobiella samhällena från Lands­­­ortsdjupet med mikrobiella samhällen från andra marina miljöer för att utröna om den karakteristiska miljön i Landsortsdjupet återspeglade de mikro­biella samhällen som lever där. För att undersöka vilka mikroorganismer samt vilka mikrobiella ekosystemfunktioner som var aktiva i det anoxiska sedimentet i Lands­ortsdjupet användes metatranskriptomik. Resultaten visade en stark kor­re­lation mellan miljöparametrarna syrehalt, salinitet och temperatur och för­del­ningen av mikrobiell taxa och i synnerhet mikrobiell funktion längs Lands­orts­djupets transekt. De mikrobiella samhällena uppvisade en funktionell kapa­citet förenlig med en livsstrategi beroende av organiskt material som sjunker genom vattenkolonnen som en konsekvens av eutrofiering. Eutrofa förhållanden med hög halt av organiskt material var även återspeglad i metatranskriptomet från det anoxiska sedimentet, som indikerade aktiv mineralisering av organiskt kol genom anaerob heterotrof-autotrof synergism. Nya möjliga kopplingar mellan kväve- och svavelmetabolism identifierades i det anoxiska vattnet. Vidare visade resultat från metatranskriptom-analys att livsdugliga cyanobakterier var abun­danta i det mörka och anoxiska sedimentet, vilket även detta kan vara en konse­kvens av sjunkande organiskt material. Hög abundans och hög transkribering av integrongener kunde identifieras som ett karakteristiskt kännetecken hos de mikro­biella samhällena i Landsortsdjupet vilket skulle kunna förse dem med en me­kanism för anpassning till miljöförändringar. Sammanfattningsvis dokumen­terar denna avhandling tydligt vilken påverkan eutrofiering och syrebrist har på mikrobiella funktioner. Dessutom för den specifikt kunskapen om mikrobiella processer i anoxiska djupvattensediment framåt på både genom- och transkrip­tions­nivå. Mot bakgrund av en predicerad ökning av syrebristen i marina mil­jöer, bidrar denna avhandling med information som är viktig för att kunna förutse vilka effekter anoxiska förhållanden kan komma att få på ekosystemfunktioner i marina miljöer och i brackvattenmiljöer i synnerhet.

Gotska Sandön is the Baltic ocean’s most isolated island, located approximately 40 kilometres north from the closest civilisation. Today the island serves as a national park and a tourist attraction. The remoteness has made the island a difficult place to reach both in the past and today. Yet, excavations on the island show that human activity existed long before tourists arrived.                     The study observes Gotska Sandön through a long-term perspective by examining the osteological and archaeological findings from the island. The study is part of a larger project conducted by Uppsala university and Södertörns högskola. The purpose of the study is to examine the historic human activity on the island to determine the island’s importance for humans in the past. Therefore, this paper examines all ages where human activity can be traced, resulting in a perspective from the stone age to present-time.         Results indicate human activity through different eras where the island has worked as a hunting ground as well as a place for rituals such as funeral sites. Conclusions that can be drawn from the study is that the island has had different meanings through different times, ritual such as functional. The study finds a strong connection between human activity and seal hunting throughout the ages and indicates the impact seal hunting has had for human survival.

The purpose of this thesis is to make a thorough but compact description of the international laws concerning solid garbage generated by vessels and sludge treatment. It is also to construct a pamphlet that can be used as a guide by ports when constructing their own information sheets to the vessels. The questions given to us from Baltic Master II were: what does the international legislation state about waste handling from vessels and in the port facilities, both sludge and solid garbage? Describe routines for receiving sludge, with concern taken to the rules that apply today. Describe routines for receiving sorted garbage and recycling, with concern taken to the rules that apply today. Look at the present symbols and labelling and develop a standard for vessels and port facilities. To solve these questions we choose an investigative method based on a literature study. The research of earlier studies showed that the parties involved consider the waste- and sludgetreatment to be flawed. In some cases the problems are fictitious or exaggerated. The main problem originates from the fact that there are no uniform routines for the interaction between vessel and port. Although there is more then one way to deal with this problem, we have concluded that the best way to improve the present day situation is to implement uniform routines. To make the routines effective they should be developed and agreed upon by the parties involved taking into consideration present day international legislation. In this thesis we present a suggestion on such a routine.

<p>A low content of organic matter, which is largely refractory in nature, is characteristic of most sediments, meaning that aquatic deposit-feeders live on a very poor food source. The food is derived mainly from sedimenting phytodetritus, and in temperate waters like the Baltic Sea, from seasonal phytoplankton blooms. Deposit-feeders are either bulk-feeders, or selective feeders, which preferentially ingest the more organic-rich particles in the sediment, including phytodetritus, microbes and meiofauna.</p><p>The soft-bottom benthos of the Baltic Sea has low species biodiversity and is dominated by a few macrobenthic species, among which the most numerous are the two deposit-feeding amphipods <i>Monoporeia affinis</i> and<i> Pontoporeia femorata</i>, and the bivalve <i>Macoma balthica</i>. This thesis is based on laboratory experiments on the feeding of these three species, and on the priapulid <i>Halicryptus spinulosus.</i> </p><p>Feeding by benthic animals is often difficult to observe, but can be effectively studied by the use of tracers. Here we used the radioactive isotope ¹⁴C to label food items and to trace the organic matter uptake in the animals, while the stable isotopes ¹³C and¹⁵N were used to follow feeding on aged organic matter in the sediment. </p><p>The abundance of<i> M. balthica</i> and the amphipods tends to be negatively correlated, i.e., fewer bivalves are found at sites with dense populations of amphipods, with the known explanation that newly settled <i>M. balthica</i> spat are killed by the amphipods. Whether the postlarvae are just accidentally killed, or also ingested after being killed was tested by labelling the postlarvae with ¹⁴C and Rhodamine B. Both tracer techniques gave similar evidence for predation on and ingestion of postlarval bivalves. We calculated that this predation was likely to supply less than one percent of the daily carbon requirement for <i>M. affinis</i>, but might nevertheless be an important factor limiting recruitment of <i>M. balthica. </i></p><p>The two amphipods <i>M. affinis</i> and <i>P. femorata </i>are partly vertically segregated in the sediment, but whether they also feed at different depths was unknown. By adding fresh 14C-labelled algae either on the sediment surface or mixed into the sediment, we were able to distinguish surface from subsurface feeding. We found <i>M. affinis</i> and <i>P. femorata</i> to be surface and subsurface deposit-feeders, respectively. </p><p>Whether the amphipods also feed on old organic matter, was studied by adding fresh ¹⁴C-labelled algae on the sediment surface, and using aged, one-year-old ¹³C- and ¹⁵N-labelled sediment as deep sediment. Ingestion of old organic matter, traced by the stable isotopes, differed between the two species, with a higher uptake for <i>P. femorata</i>, suggesting that <i>P. femorata</i> utilises the older, deeper-buried organic matter to a greater extent.</p><p>Feeding studies with juveniles of both <i>M. affinis</i> and <i>P. femorata</i> had not been done previously. In an experiment with the same procedure and treatments as for the adults, juveniles of both amphipod species were found to have similar feeding strategies. They fed on both fresh and old sediment, with no partitioning of food resources, making them likely to be competitors for the same food resource. </p><p>Oxygen deficiency has become more wide-spread in the Baltic Sea proper in the last half-century, and upwards of 70 000km² are now devoid of macrofauna, even though part of that area does not have oxygen concentrations low enough to directly kill the macrofauna. We made week-long experiments on the rate of feeding on ¹⁴C-labelled diatoms spread on the sediment surface in different oxygen concentrations for both the amphipod species, <i>M. balthica</i> and <i>H. spinulosus. </i>The amphipods were the most sensitive to oxygen deficiency and showed reduced feeding and lower survival at low oxygen concentrations.<i> M. balthica</i> showed reduced feeding at the lowest oxygen concentration, but no mortality increase. The survival of <i>H. spinulosus</i> was unaffected, but it did not feed, showing that it is not a surface deposit-feeder. We conclude that low oxygen concentrations that are not directly lethal, but reduce food intake, may lead to starvation and death in the longer term.</p>

<p>Summer blooms of filamentous, diazotrophic cyanobacteria are typical of the Baltic Sea Proper, and are dominated by <i>Aphanizomenon </i>sp<i>.</i> and the toxic <i>Nodularia spumigena.</i> Although occurring every summer, the blooms vary greatly in timing and spatial distribution, making monitoring difficult and imprecise. This thesis studies how the spatial variability of Baltic cyanobacterial blooms influences estimates of abundance, vertical and horizontal distribution and N₂-fixation. Implications for sampling and monitoring of cyanobacterial blooms are also discussed.</p><p>The results of the thesis confirm the importance of diazotrophic cyanobacteria in providing N for summer production in the Baltic Proper. It also highlights the large spatial and temporal variation in these blooms and argues that improved spatial coverage and replication could make monitoring data more useful for demonstrating time trends, and for identifying the factors regulating the blooms. The vertical distribution of <i>Aphanizomenon</i> and <i>Nodularia</i> was found to be spatially variable, probably as a combination of species-specific adaptations and ambient weather conditions. Vertical migration in <i>Aphanizomenon</i> was more important towards the end of summer, and is probably regulated by a trade-off between P-availability and light and temperature.</p>

<p>The aim of this thesis was to estimate and possibly quantify ocean flow by utilizing conventional and novel observational methods as well as model results. Motionally induced voltages, from a cable-based observational system in the Baltic Sea, were analysed to determine their utility for ocean monitoring. The data set was examined as regards the influence of single- and multi-layer flow. Correlation analyses undertaken in the first study showed that the geoelectric installation is capable of providing good estimates of the net flow across the Visby-Västervik transect. The second study focused on possible effects of multi-layer flow on the signal. Comparisons were made with tidal-gauge geostrophic flow estimates, and a good agreement was found, except for a few brief winter periods characterized by significant discrepancies. The velocity fields from a three-dimensional model showed that these events coincided with strong surface and bottom currents, and hence the attenuated voltage signal was suggested as being caused by the non-uniform velocity distribution.</p><p>The third study dealt with the deep-water flow through the Understen-Märket trench. Observational data indicated that this flow could be described by applying hydraulic theory. Since the passage is narrow compared to the internal Rossby radius of deformation, rotational effects could be neglected to lowest order. The theoretical predictions proved to agree well with the observational results.</p><p>The final study examined the effects of the heat flux and the wind forcing on the circulation in Bahía de Concepción, Chile, where three field surveys were undertaken during the extended austral summer 2002. Hydrographic and current measurements were compared to local tidal-gauge records. Rough estimates of the barotropic and the baroclinic flow across the transect indicated an unusual vortex circulation during periods of weak wind forcing and strong surface heating; results which were corroborated by numerical simulations.</p>

<p>The purpose of this thesis is to make a thorough but compact description of the international laws concerning solid garbage generated by vessels and sludge treatment. It is also to construct a pamphlet that can be used as a guide by ports when constructing their own information sheets to the vessels. The questions given to us from Baltic Master II were: what does the international legislation state about waste handling from vessels and in the port facilities, both sludge and solid garbage? Describe routines for receiving sludge, with concern taken to the rules that apply today. Describe routines for receiving sorted garbage and recycling, with concern taken to the rules that apply today. Look at the present symbols and labelling and develop a standard for vessels and port facilities. To solve these questions we choose an investigative method based on a literature study. The research of earlier studies showed that the parties involved consider the waste- and sludgetreatment to be flawed. In some cases the problems are fictitious or exaggerated. The main problem originates from the fact that there are no uniform routines for the interaction between vessel and port. Although there is more then one way to deal with this problem, we have concluded that the best way to improve the present day situation is to implement uniform routines. To make the routines effective they should be developed and agreed upon by the parties involved taking into consideration present day international legislation. In this thesis we present a suggestion on such a routine.</p>

<p>Passagerarna behöver mera tid än säkerhetsinformation eftersom passagerarna har så bråttom att komma ombord, boka bord och handla tax-free. Därmed missar passagerarna viktig säkerhetsinformation som alltid ges vid avgång via fartygets högtalarsystem. Det finns klar och tydlig säkerhetsinformation ombord. Det viktiga är sättet att ge information än att ge mera information. Idag informeras passagerarna via videoskärmar, utrymningskartor på hyttdörrar, via högtalarsystemet ombord, säkerhetsbroschyrer i hytter och information, välutbildad besättning och det är väl skyltat ombord. Att överinformera om riskerna ombord kan skapa en oro bland passagerarna. Passagerarna är oftast ute på nöjeskryssningar och vill inte bli påminda om tidigare fartygskatastrofer eller om risker.</p><p>Det är upp till varje passagerare att söka säkerhetsinformation och hur passagerarna tar till sig säkerhetsinformationen beror till viss del på deras attityd och intresse att ta till sig säkerhetsinformationen. Det finns säkerhetsinformation att tillgå ombord och detta ger passageraren ett väsentligt bättre utgångsläge att klara sig om det bli aktuellt att utrymma fartyget.</p><p>Det är svårt att få information om säkerheten innan avgång, eftersom passageraren hänvisas till rederiernas hemsida. Rederierna skyltar inte med säkerhetsinformation på startsidan, utan passageraren måste själv leta sig vidare till denna information.</p><p>Rederierna har en god säkerhetskultur och med detta menas, safety first och ständig förbättring.</p><p> </p>