Sustainable management of natural resources requires an in-depth understanding of the interplay between social and ecological change. Linked social-ecological systems (SES) have been described as complex adaptive systems (CAS), which mean that they are irreducible, exhibit nonlinear dynamics, have interactions across scales and are uncertain and unpredictable. These propositions have however rarely been tested empirically, in part due to a lack of methodological approaches and suitable datasets. In this thesis, I address this methodological and empirical gap in a study of long-term change of Baltic Sea fisheries. In Paper I, we develop the concept of fishing style through integrating multivariate statistical analysis and in-depth interviews. We thereby identify an intermediate level of detail for analyzing social-ecological dynamics, embracing the case specific and context dependent approaches of the social sciences with the generalizable and quantifiable approaches from the natural sciences. In Paper II we ask: How has the Baltic Sea fishery been regulated over time, and can we identify a way to quantify regulations in order to be able to analyze their effects? We analyze all regulatory changes in Sweden since 1995 with a new methodology and conclude that there is a clear trend towards increased micro-management. In Paper III, we use the fishing styles developed in Paper I and examine how they have changed over time. We relate these changes to the dynamics of regulation (Paper II), as well as to the dynamics of fish stocks and prices. We conclude that regulation has been the main driving force for observed changes, but also that regulation has prompted significant specialization and decline in flexibility for fishers over time. These changes are unintended consequences and may represent a looming risk for the long-term sustainability of this social-ecological system. Paper IV zooms in on a particular fishery, the pelagic trawl fishery for sprat Sprattus sprattus and Atlantic herring Clupea harengus, mainly targeted for the production of fishmeal and fish oil. Suspicions of non-compliance in this fishery motivated us to apply a statistical approach where we used socioeconomic data to re-estimate the historical catches in this fishery (a novel approach to catch-reconstruction estimates). We found that catches had been significantly underreported over several years, with consequences for the quality of stock assessments and management. The study underlines the importance of understanding linked social, economic and ecological dynamics for sustainable outcomes. Finally, Paper V takes a longer historical look at the Baltic Sea fishery, using regionally disaggregated data from 1914-2009 (96 years), which were analyzed with a novel type of nonlinear statistical time-series methods (Empirical Dynamical Modeling). Our analysis explicitly recognized the potential nonlinear dynamics of SES and showed high predictability across regions of catches and prices of cod Gadus morhua and herring. The signal was generally nonlinear and predictability decreased strongly with time, suggesting that the dynamics of this SES are ever-changing. To our knowledge, this is the first long-term analysis of a SES using empirical data and methods developed from the CAS field of research. The main contributions of this thesis are the integrated analysis of social and ecological data, the development of novel methods for understanding SES dynamics, insights on the ever-changing nature of CAS and the quantitative analysis of management outcomes. Future work should focus on assessing the generality of these findings across a broad range of SES and evaluate alternative governance approaches given the complexity and uncertainty of SES suggested by this thesis. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 5: Manuscript.</p>

In this study, an analysis of upwelling and biological activities impact on the seawater pCO2 variability was done to improve the knowledge about the pCO2 variability in seawater in the Baltic Sea. During upwelling activity, CO2 rich waters are upwelled to the surface. This influences air-sea CO2 flux and thus the net uptake/emission of CO2 by the sea. pCO2 and SST measurements from a SAMI sensor, located at the Östergarnsholm site in the Baltic Sea, and SST satellite data, was used to identify periods affected by upwelling activity. A strong variability due to upwelling activity was observed on the pCO2 concentration. The frequency of upwelling activity at the Östergarnsholm site was estimated to be around 20 % of the time from May-November. The relationship between pCO2 and SST during upwelling activity was found to depend of the month. In November, this relationship can be used to characterise the effect of upwelling, but for the other months there are no differences between the none- upwelling periods and the upwelling periods. Another type of period, characterized by a diurnal variability of pCO2 mainly driven by the biological effect, was also observed. / I denna studie undersöktes hur uppvällning och biologisk aktivitet påverkar koncentrationen av pCO2 i havet. Detta gjordes för att få ökad förståelse för korttidsvariationen av pCO2 i Östersjön. Under uppvällning pressas CO2-rikt vatten upp till ytan. Detta påverkar flödet av CO2 mellan hav och atmosfär och då även det totala upptaget/utsläppet av CO2 från havet. I studien användes pCO2 och SST mätningar från en SAMI-sensor, placerad vid Östergarnsholm i Östersjön, och en del satellitdata för att identifiera perioder påverkade av uppvällning. Det observerades att uppvällnings inverkan på koncentrationen av pCO2 varierar kraftigt. Frekvensen av uppvällning vid Östergarnsholm uppskattades vara ungefär 20 % av tiden under maj-november. Relationen mellan SST och pCO2 under perioder med uppvällning observerades variera från maj-november. I november kan denna relation användas till att uppskatta effekten av uppvällning men under de andra månaderna är relationen under uppvällning för lika relationen under icke- uppvällning. Även en annan slags perioder observerades; under dessa perioder observerades en dygnscykel av pCO2, driven av biologisk aktivitet.

Žiemojantys vandens paukščiai Lietuvos pajūryje 2006, 2007 ir 2008 m. žiemojimo laikotarpiu tirti naudojant standartinę apskaitų nuo kranto metodiką. Gausiausiai stebėtos rūšys buvo: nuodėgulė, ledinė antis, didysis dančiasnapis, ausuotasis kragas, klykuolė, sibirinė gaga. Darbe yra pateikiama 2006, 2007 ir 2008 metų žiemos stebėjimo sezonų duomenų analizė, kurioje yra nagrinėjama vandens paukščių rūšinė sudėtis tiek 2006, 2007 ir 2008 metais atskirai, bei tarp atskirų teritorijų skirtingais metais. Palangos priekrantė 2006, 2007 ir 2008 metų stebėjimo sezonais buvo svarbi didžiųjų dančiasnapių, ausuotųjų kragų, klykuolių, ledinių ančių ir sibirinių gagų susitelkimo vieta. Priekrantė ties Kuršių nerija 2006–2007 metų stebėjimo sezonais buvo svarbi žiemojančioms nuodėgulėms, ledinėms antims ir ausuotiesiems kragams. Taip pat nagrinėjau žiemojančių vandens paukščių pasiskirstymą Lietuvos Baltijos jūros priekrantėje ties Palanga, bei ties Kuršių nerija tais pačiais, bei skirtinagais tyrimų sezonais. Ledinių ančių pagrindinės sankaupos stebėtos ties Giruliais ir mažesnė dalis iki Palangos tilto, nuodėgulių - ties Juodkrante ir Smiltyne. Klykuolių didesnės sankaupos stebėtos tarp Karklės ir Palangos tilto. Ausuotųjų kragų pasiskirstymas priekrantėje sąlyginai tolygus tiek ties Kuršių nerija, tiek ties Palanga. / Wintering wterbirds in Lithuanian costal waters were investigated in 2006–2007–2008 standart land-based surveys were used. Abuot 11900 in 2006, 6600 in 2007 and 4192 in 2008 waterbirds were cuonted. 20 species were recorded wintering in Lithuanian inshore waters of the Baltic sea. Velvet Scoter, Long-tailed Duck, Goosander, Great Crested Grebe, Goldeneye, Steller‘s Eider were the most numeruos species. Analysis of the wintering waterbird species composition in diferent years in the same study site and in different years in the same site in 2006–2007–2008 wintering seasons is presented. The coastal waters off the Palanga were important for wintering Long-tailed Ducks, Goosanders, Great Crested Grebes, Goldeneyes, Steller‘s Eiders in 2006–2007–2008 seasons. The coastal waters off the Curonian Spit were important for wintering Velvet Scoters, Long-tailed Ducks, Great Crested Grebes. Distribution of wintering waterbirds in the Lithuanian inshore waters in 2006–2007–2008 wintering seasons was also analysed. The greatest concentrations of Long-tailed Ducks were observed near the Giruliai and smaller numbers – all the way to Palanga bridge in the north, Velvet Scoters – between Juodkrante and Smiltyne. The greatest concentrations of Goldeneyes were observed between Karkle and the Palanga bridge. Great Crested Grebes were rather evenly distributed along the coastal waters both off the Palanga and the Curonian Spit coasts.

Diss. (sammanfattning) Umeå : Sveriges lantbruksuniv. / Härtill 5 uppsatser.

Issued also as thesis, Kiel, 1963. / Offa-Bücher, Bd. 19.

Thesis (doctoral)--Stockholms Universitet, 2003. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (p. 304-317).

Biogeochemical processes in the marine biosphere are important in global element cycling and greatly influence the gas composition of the Earth’s atmosphere. The nitrogen cycle is a key component of marine biogeochemical cycles. Nitrogen is an essential constituent of living organisms, but bioavailable nitrogen is often short in supply thus limiting primary production. The largest input of nitrogen to the marine environment is by N2-fixation, the transformation of inert N2 gas into bioavailable ammonium by a distinct group of microbes. Hence, N2-fixation bypasses nitrogen limitation and stimulates productivity in oligotrophic regions of the marine biosphere. Extensive blooms of N2-fixing cyanobacteria occur regularly during summer in the Baltic Sea. N2-fixation during these blooms adds several hundred kilotons of new nitrogen into the Baltic Proper, which is similar in magnitude to the annual nitrogen load by riverine discharge and more than twice the atmospheric nitrogen deposition in this area. N2-fixing cyanobacteria are therefore a critical constituent of nitrogen cycling in the Baltic Sea. In this thesis N2 fixation of common cyanobacteria in the Baltic Sea and the direct fate of newly fixed nitrogen in otherwise nitrogen-impoverished waters were investigated. Initially, the commonly used 15N-stable isotope assay for N2-fixation measurements was evaluated and optimized in terms of reliability and practicality (Paper I), and later applied for N2-fixation assessments (Paper II–IV). N2 fixation in surface waters of the Baltic Sea was restricted to large filamentous heterocystous cyanobacteria (Aphanizomenon sp., Nodularia spumigena, Dolichospermum spp.) and absent in smaller filamentous cyanobacteria such as Pseudanabaena sp., and unicellular and colonial picocyanobacteria (Paper II-III). Most of the N2-fixation in the Northern Baltic Proper was contributed by Aphanizomenon sp. due to its high abundance throughout the summer and similar rates of specific N2-fixation as Dolichospermum spp. and N. spumigena. Specific N2 fixation was substantially higher near the coast than in an offshore region (Paper II). Half of the fixed nitrogen was released as ammonium at the site near the coast and taken up by non-N2-fixing organisms including phototrophic and heterotrophic, prokaryotic and eukaryotic planktonic organisms. Newly fixed nitrogen was thereby rapidly turned-over in the nitrogen-depleted waters (Paper III). In colonies of N. spumigena even the potential for a complete nitrogen cycle condensed to a microcosm of a few millimeters could be demonstrated (Paper IV). Cyanobacterial colonies can therefore be hot-spots of nitrogen transformation processes potentially including nitrogen gain, recycling and loss processes. In conclusion, blooms of cyanobacteria are instrumental for productivity and CO2 sequestration in the Baltic Sea. These findings advance our understanding of biogeochemical cycles and ecosystem functioning in relation to cyanobacterial blooms in the Baltic Sea with relevance for both ecosystem-based management in the Baltic Sea, and N2-fixation and nitrogen cycling in the global ocean. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 2: Manuscript.</p>

Climate change is a pressing issue caused by the systematic increase of greenhouse gasses (GHG). One way to avoid higher GHG emissions is through an increased use of public transportation, transitioning society away from the personal automobile. Public transportation is more sustainable than the personal automobile as its emissions per person are less and it takes up significantly less space. Sustainability is defined through the principle-based definition of the Framework for Strategic Sustainable Development (FSSD). This research studied barriers and best practices to the use of public transportation in the South Baltic Sea Region (SBSR), in cooperation with the EU funded InterConnect Project. The research team was able to use the resources of the InterConnect Project for their methods in order to discover perceived barriers and potential best practices and ideas to overcome these barriers through the stakeholder perspective. The research team concludes that by addressing the perceived barriers, a first step towards transitioning society within the SBSR towards more sustainable transportation can be done. As transportation is complex and connected to other systems, the need for a systems perspective and a strategic and collaborative approach was identified. This could be achieved through using the FSSD in the SBSR.

Thiamine (vitamin B1) is involved in several basal metabolic processes. It is an essential compound for many organisms and in aquatic systems it is mainly produced by phytoplankton and prokaryotes and transferred to higher trophic levels through grazing and predation. The occurrence of thiamine deficiency in top predators has been reported from several aquatic systems. In the Baltic populations of the Atlantic salmon (Salmo salar) this has been observed since 1974 and recently thiamine deficiency has also been reported for Baltic sea birds. This thesis aims at investigating what processes that governs the flow of thiamine from the primary producers to top predators via zooplankton grazers and planktivoric fish. Paper I showed that abiotic stress factors such as salinity, temperature and light conditions can alter the thiamine content of phytoplankton. Paper II showed that abiotic factors indirectly can affect the stress resistance of zooplankton grazers by changing the nutritional quality of their food. In Paper III we found that the in situ thiamine content of zooplankton grazers was directly affected by that of the phytoplankton diet. In Paper IV we found a similar connection between the thiamine contents of Baltic salmon and herring, one of the major salmon prey species. In Paper V we looked at the thiamine content of the pelagic food web of the Baltic Sea as a whole and found a pattern of trophic dilution; the higher the trophic level of an organism (i.e. the further away from the source of thiamine in the food web), the lower was its thiamine content. In all, the results of this thesis suggests a bottom up effect on the thiamine status of the higher trophic levels of  the Baltic Sea and that external factors, both natural and man-made, have the capability to affect the thiamine status of the plankton communities and thereby the whole Baltic ecosystem. Thiamine and other micronutrients are not something generally considered in the environmental management of aquatic systems but the results of this thesis suggest that ecological disturbances indirectly can have negative effects on top predators via a disrupted supply of essential substances. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript. Paper 5: Manuscript.</p>

Eutrophication is a major concern in the Baltic Sea and it is affecting macrophyte communities by promoting the growth of opportunistic algae and decreasing the cover of perennial macrophyte species via shading. It is however uncertain how common eutrophication and its symptoms are in the northern parts of the Baltic Sea, the Botnian Sea. The aim of this study was to evaluate if Sörleviken, a bay in the Bothnian Sea, show signs of increased eutrophication pressure in 2020 compared to 2007 based on changes in macrophyte cover and composition. The macrophyte community was inventoried with under-water video techniques in 2020 along three transects, matching transects previously inventoried by a diver in 2007. The three transects were located in the inner, middle and the outer parts of the bay. The results showed that macrophyte diversity was lower in 2020 than in 2007 along the outer transect, but overall, the total cover of macrophytes, relative cover of opportunistic algae, species richness and evenness remained unchanged. A possible higher presence of Stuckenia pectinata (former Potamogeton pectinatus) and a possible lower presence of Chara aspera in 2o2o compared to 2007 might be evidence of higher eutrophication pressure in 2020. However, by observing the general changes in the macrophyte community, this study only provides weak or inconclusive signs of increased eutrophication pressure, thus Sörleviken shows no signs of either improvement of or further increases in eutrophication pressure by 2020 compared to the observations in 2007.