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Naturvårdsverket rankar övergödningen som det allvarligaste hotet mot Östersjön. Strategin för att bekämpa övergödningen i Östersjön har varit att reducera antropogena utsläpp av fosfor och kväve från punktkällor och diffusa källor. Många forskare anser att primärproduktionen i egentliga Östersjön huvudsakligen är begränsad av kväve varför Sverige har infört ett ambitiöst och kostsamt program för avancerad kväverening på reningsverk. Andra experter hävdar istället att reducerade kväveutsläpp är meningslösa eller rent av skadliga. I ljuset av dessa fundamentalt olika åsikter och de helt motsatta strategier de innebär syftar denna studie till att försöka klargöra vilka åtgärder som borde vidtas för att minska övergödningen genom att undersöka området Himmerfjärden som ofta används som ett exempel på lyckad kväverening. Området har också studerats intensivt sedan 1970-talet. Detta arbete har använt en processbaserad dynamisk massbalansmodell för salt för att beräkna vattenutbytestider i Himmerfjärden. Flöden av vatten och näringsämnen till och från fjärden har beräknats och det har visats att bidraget av kväve och fosfor till Himmerfjärden från reningsverket är mycket marginellt jämfört med bidraget från Östersjön. Denna studie har också genom att granska litteratur och mätdata från Himmerfjärden visat att det finns goda skäl att ifrågasätta hypotesen om att primärproduktionen i Himmerfjärden skulle vara långsiktigt begränsad av kväve. Resultaten av denna studie kommer att användas i framtida massbalansmodelleringar av fosfor, kväve och cyanobakterier i Himmerfjärden. / The Swedish Environmental Protection Agency has ranked eutrophication as the most severe threat to the Baltic Sea. The strategy to combat the eutrophication in the Baltic has been to reduce antrophogenous emissions of phosphorus and nitrogen from point and diffuse sources. Many scientists argue that the primary production in the Baltic proper is primarily limited by nitrogen which is why Sweden and other countries have implemented an ambitious and expensive program of advanced nitrogen removal in sewage treatment plants. Other experts argue that reduced nitrogen load to the Baltic Sea is either pointless or even harmful. In the light of these fundamentally different views and the very opposite management strategies they imply, this study aims to more bring clarity to which measures should be taken to reduce eutrophiction by investigating the area of Himmerfjärden. Himmerfjärden is often used as an example of successful removal of nitrogen and the area has been intensively monitored since the 1970’s. This work used a process-based dynamic mass balance model for salt to calculate water retention times in Himmerfjärden. Water and nutrient flows to and from the bay have been calculated. It was shown that the contribution of nutrients to Himmerfjärden from the treatment plant is small compared to the contribution from the Baltic Sea. This study showed by reviewing literature on Himmerfjärden that there are good reasons to question the hypothesis of Himmerfjärden being nitrogen limited in the long-run. The findings of this study will be used in future mass balance modelling of phosphorus, nitrogen and cyanobacteria in Himmerfjärden.

Log-boats within the Ertebölle culture have had a broad use in the society. From social usesas transport and communication devises to economical uses within hunting and fishing. Thelog-boats have been quite large, larger than log-boats in later periods. With a length of up to 10 meters and a width of 0,5-1 meter the log-boat have been big enough to carry a family andthere gear along the cost. Even though the long and narrow shape of the log-boat have made them mostly suitable for calm and shallow water they have still aloud the people of theErtebölle culture to cross major waters such as the sound between Denmark and Sweden.

The purpose of this thesis is to examine the earliest active time period of the harbour of Västergarn on the island of Gotland. The exact time of the founding of Västergarn has been debated for almost a century. Extensive excavations were conducted between 2005 and 2013 by the University of Gotland which resulted in a large amount of pottery, of which the earliest type was the Baltic Sea ware. I aim to add to this discussion with a study of the morphology and chronology of the Baltic Sea ware found at the site. This type of pottery is an excellent archaeological source material for exploring the early history of Västergarn. Because the Baltic Sea ware is found all over the excavated area it provides evidence for the material needs of a growing urban population. As an everyday resource for the people of Västergarn it also indicates when the site was permanently settled.    The study of the morphology and the distribution pattern clearly shows that Västergarn was well populated already in the 12th century. Such an early date for occupation of the site has been questioned in earlier research. There is now archaeological evidence to argue that the settlement within the earthen rampart was probably founded in the second half of the 11th century. In the same time period Visby was established as an urban site. Furthermore, based on a topographical study comparing the presence of Baltic Sea ware in different trenches with the shore line I argue the rampart was constructed somewhere between circa 1000 and 1200 A.D. / Syftet med denna uppsats är att undersöka den tidigaste aktivitetsperioden i den gotländska hamnen Västergarn. Den exakta tiden för Västergarns grundande har debatterats i nästan ett århundrade. Extensiva utgrävningar genomförda av Högskolan på Gotland mellan 2005 och 2013 resulterade i en stor mängd keramik, varav östersjökeramiken är den äldsta. Jag ämnar utveckla denna diskussion med en studie av morfologin och kronologin av östersjökeramiken som finns på platsen. Denna godstyp är ett utmärkt arkeologiskt källmaterial i undersökningen av Västergarns tidiga historia. Då östersjökeramiken har hittats på nästan hela det utgrävda området bevisar det att en växande befolkning fanns på platsen. Som vardagsgods i Västergarn antyder keramiken också när platsen blev permanent befolkad.    Studien av östersjökeramikens morfologi och korologi visar också tydligt att Västergarn var välbefolkat redan under 1100-talet. En så tidig datering för platsens befolkning har länge varit ifrågasatt inom tidigare forskning. Nu finns det dock arkeologiskt bevis att platsen troligen blivit grundad under den andra halvan av 1000-talet. Staden Visby grundades under samma tidsperiod. Fortsättningsvis, med basis i en topografisk analys som jämför östersjökeramikens närvaro i vissa schakt med strandlinjen argumenterar jag för att Västergarnsvallen byggdes någon gång mellan cirka år 1000 och 1200.

The reproductive success for pelagic spawning Baltic flounders is strongly linked to the hydrodynamics in the spawning areas. Egg survival is dependent upon the ability to achieve neutral buoyancy at a depth interval where temperature and oxygen concentrations are favourable for egg development. The main focus of this thesis was to compare egg survival probabilities of pelagic eggs from Baltic flounder in the Bornholm, Gdansk and Gotland basins, prior to and after the saline water inflow in December 2014. The results showed greatly enhanced survival probabilities in Bornholm basin 2015 (p<0.01), as egg survival increased from 47% in 2014 to 100% the following year. In Gdansk basin the situation was similar, and survival probability increased from 13% to 100% (p<0.01). In Gotland basin no difference in survival probability was identified, although the dominant cause of mortality shifted from sedimentation, i.e. due to low salinity conditions in 2014, to oxygen deficiency in 2015 (p<0,01). / BONUS INSPIRE-project, the joint Baltic Sea research and development programme (Art 185), funded jointly by the European Union’s Seventh Programme for research, technological development and demonstration and the Swedish Research Council Formas

Persistent organic pollutants such as polychlorinated biphenyls (PCBs), DDT and polybrominated diphenyl ethers (PBDEs) tend to accumulate in biota and are transferred through the aquatic food web, which result in a high accumulation in marine mammals. In recent years various novel flame retardants (nBFRs), which have replaced the banned PBDEs, have also started to occur in the environment. These nBFRs have similar properties as PBDEs, such as long-range transport and accumulation in biota. The purpose with this study was to evaluate a method by using pre-packed silica columns for quantification of PCBs, DDT, PBDEs and nBFRs in seal blubber, in order to facilitate the pre-treatment and decrease the time. To elute the different POPs from the pre-packed silica column; hexane, toluene and dichloromethane were used in different stages. By using this method levels of PCB and DDT were determined. For DDT the concentration was 8.28 ng/g lipid and 8.94 ng/g lipid for the two samples that was analysed, and the analysis of the PCBs showed a higher trend for the higher chlorinated PCBs. As the pre-packed silica columns are a relative new method. Further studies are therefore needed on these columns to further improve the sample clean-up and fractionation of the different POPs in environmental samples.

Global records of temperature show a warming trend both in the atmosphere and in the oceans. Current climate change scenarios indicate that global temperature will continue to increase in the future. The effects will however be very different in different geographic regions. In northern Europe precipitation is projected to increase along with temperature. Increased precipitation will lead to higher river discharge to the Baltic Sea, which will be accompanied by higher inflow of allochthonous organic matter (ADOM) from the terrestrial system. Both changes in temperature and ADOM may affect community composition, altering the ratio between heterotrophic and autotrophic organisms. Climate changes may thus have severe and complex effects in the Baltic Sea, which has low species diversity and is highly vulnerable to environmental change. The aim of my thesis was to acquire a conceptual understanding of aquatic food web responses to increased temperature and inputs of ADOM. These factors were chosen to reflect plausible climate change scenarios. I performed microcosm and mesocosm experiments as well as a theoretical modeling study. My studies had a holistic approach as they covered entire food webs, from bacteria and phytoplankton to planktivorous fish. The results indicate a strong positive effect of increased temperature and ADOM input on the bacterial community and the microbial food web. However, at the prevailing naturally low nutrient concentrations in the Baltic Sea, the effect of increased temperature may be hampered by nutrient deficiency. In general my results show that inputs of ADOM will cause an increase of the bacterial production. This in turn can negatively affect the production at higher trophic levels, due to establishment of an intermediate trophic level, consisting of protozoa. However, the described effects can be counteracted by a number of factors, as for example the relatively high temperature optimum of fish, which will lead to a more efficient exploitation of the system. Furthermore, the length of the food web was observed to be a strong regulating factor for food web responses and ecosystem functioning. Hence, the effect of environmental changes may differ quite drastically depending on the number of trophic levels and community composition of the system. The results of my thesis are of importance as they predict possible ecological consequences of climate change, and as they also demonstrate that variables cannot be examined separately. / <p>This thesis was supported by grants from the Swedish Research Council FORMAS to AA and SL (217-2006-674), the Centre for Environmental Research in Umeå (CMF) to UB, AA and SL, and by the Swedish strategic research program ECOCHANGE to Umeå University.</p>

Anthropogenic environmental changes can serve as drivers for evolutionary responses in wild populations. To predict the long-term impact of anthropogenic changes on populations, it is crucial to understand the genetic effects caused by these disturbances. The Baltic Sea is considered to be one of the world’s most contaminated seas, and the increase of anthropogenic chemical pollution is a major threat to its ecosystems. This thesis assesses the impact of harbors and sewage treatment plants on physiological traits and genetic structure of resident populations of blue mussels at replicated sites in the Baltic Sea. The initial evaluation of the overall genetic pattern in blue mussel populations in the Swedish West Coast, the Baltic Proper and the Bothnian Sea found genetic differentiation between the three water basins and a low genetic differentiation within each basin, especially within the Baltic Proper. Despite the low genetic differentiation among blue mussels within the Baltic Proper, a parallel genetic differentiation associated with sewage treatment plant effluents was found in this basin. This included genomic regions with a high degree of differentiation between reference sites and sites affected by sewage plants effluent. This genetic differentiation is suggested to be due to post-dispersal selection acting in each generation. In contrast, no parallel genetic differentiation was associated with harbors. We identified five genomic regions in blue mussels, showing strong signs of selection, shared among three out of four replicated reference sites and sites affected by sewage effluents in the Baltic Proper i.e. Askö, Tvärminne and Karlskrona. An initial characterization of these genomic regions revealed functions related to immune and endocrine responses, oxidative stress and shell formation. Our results indicate that selection caused by sewage effluents involves multiple loci. The same genomic regions are found across different locations in the Baltic Proper but there are also unique genomic regions at each location. No genotoxic or histopathological effects were found among blue mussels from sewage effluent-affected areas but a higher frequency of histological abnormalities in the digestive gland were observed in mussels from harbors. / Evolutionära anpassningar till miljöstörningar i marina ekosystem: genetisk ekotoxikologi i Östersjön

Forskare förutspår att den globala uppvärmningen kommer att påverka Öster-sjön och omgivande landmassor med högre temperatur och mer nederbörd. En konsekvens av högre nederbörd är ökat läckage och avrinning av sötvatten från landmassorna vilket leder till högre näringstillgång i Östersjön. Ytterligare en konsekvens av ökad tillförsel av sötvatten är utspädningseffekten av salthalten i Östersjön. Dessa förändringar kommer att påverka Östersjöns ekosystem och arterna i. Hur väl ett ekologiskt samhälle klarar av en förändrad miljö beror på minst tre faktorer; diversitet, artsammansättning och interaktionsmönster mellan arter. Denna studie undersöker interaktionen mellan mört och abborre samt hur interaktionen påverkas då salthalt, näringstillgång och temperatur förändras. Med provfiskedata från elva lokaler har interaktionen beräknats med tidsserieanalys genom att använda en multivariat autoregressiv modell. Resultaten visar att både abborre och mört har negativ effekt på varandra. Dessutom är båda arterna kraftigt täthetsberoende. Hur interaktionen påverkas av förändringar av påverkansvariablerna har studerats grafiskt. Abborres effekt på mört är den enda interaktionen som med statistisk signifikans konstateras temperaturberoende. Resultaten från studien visar att den negativa effekt abborre har på mört blir mindre då temperaturen ökar. Effekten avtar linjärt då vattentemperaturen är 15 °C. Detta tyder på att abborres reglerande effekt på mört eventuellt kommer att minska under de förväntade klimatförändringarna. / The science community predict that the rising global temperature will affect the region of Scandinavia with more precipitation and as a consequence more runoff and leakage of nutrients to the Baltic Sea. During this century salinity in the Baltic Sea is expected to decrease with up to 1.5 - 2 g / kg due to dilution from the higher runoff volumes and the temperature is expected to increase with 3 - 5 °C. All these changes will affect the Baltic Sea ecosystem and the species within it. How well an ecological community can adapt to these changes is determined by the community stability which is based on at least three factors; diversity, species composition and interaction patterns between species. This study aims to investigate the interaction patterns between perch and roach, two well represented species along the Swedish coastline, and how these interaction patterns are effected by changes in salinity, watertemperature, and nutrient load. The study used a multivariate autoregressive model (MAR(1)), which is a linear model that can be used to investigate interaction patterns. The input in the MAR(1)-model was time series based on catch per unit effort of perch and roach from eleven different places along the Swedish east coast. Both perch and roach have a negative impact on the other species, also a strong density dependence for both species were found. Temperatures effect on the interaction; perch effect on roach, is the only one in this study that is statistically significant. Perch has a strong negative effect on roach when the temperature is around 15 °C. This negative effect decreases linearly with higher temperatures.

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