Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniversitet, 2005. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2007. / Härtill 4 uppsatser.

Akademisk avhandling--Lund. / Extra t.p. with thesis note, inserted. "Källor och litteratur": p. [451]-466.

<p>During the 1960´s and 1970´s the number of grey seals in the Baltic Sea was decreasing rapidly, mostly due to hunting and toxic substances like DDT and PCB. When hunting became less intense and toxic substances decreased in the environment the grey seal population started to increase. Today grey seals are found common in the Baltic Sea and have started to become a big treat and a problem to the fishing industry. The grey seal destroys and enters fishing traps and consumes large quantities of the fish that have been caught.</p><p>The knowledge of the grey seal, like abundance and food preferences, is today limited. It is also important to define the position of the grey seal in the ecosystem in the Baltic Sea and to be able to predict changes that could occur if the population would rapidly decrease or increase. This project was therefore started in an attempt to increase the knowledge about the grey seals food preferences. The study was made in tree separate parts. Part one contained analyses of prey remains from stomachs and digestive tract from fourteen individuals put down in two geographically separate areas. The collected material from the seal digestive tract was cleaned and otoliths (hearing stones from fish), scales and back vertebra from fish eaten by the grey seal were sorted out. With the help of hard parts collected from the intestines the food preferences of the seals could be estimated. Eight different species of prey was found. The species were herring (Clupea harengus membras), sprat (Sprattus sprattus), common whitefish (Coregonus spp), perch (Perca fluviatilis), salmon (Salmo salar), trout (Salmo trutta) and roach (Rutilus rutilus). In two of the digestive tracts several individuals of the isopod Saduria entomon were found. No earlier studies describe the isopod as a food source for the grey seals in the Baltic Sea. The findings are therefore unique information. The results showed that during summer the main part of the grey seal diet in the gulf of Sundsvall and in the surrounding coastal area of Hårte was herring and sprat. No significant difference in food preferences was shown between the investigated seals from the gulf of Sundsvall and seals from the surrounding coastal area of Hårte.</p><p>The second part was made to investigate if it was possible to build a floating platform that would work as a resting place for the grey seal. The surface of the platform was covered by a layer that keeps the seal scats on the platform so that it could be collected. Otoliths from herring and common whitefish were found on the floating platform. Because the platform could not be under surveillance during the whole study some uncertainties about whether the otoliths found came from grey seal or from resting cormorants or other fish eating birds. However, the otolit size is linearly related to the fish size and this relationship can be used to track the predator. Otoliths from herring taken by grey seals and otoliths found on the platform were significantly bigger than the otoliths originating from the prey of cormorants. The results indicated that the common whitefish size was too big for a full grown cormorant bird to consume. The common whitefish size showed that it probably not had been cormorants that had deposited the otoliths on the platform. The platform method was concluded promising but it needs to be modified in order to work more effective in the future.</p><p>In the third part scats were collected from the area of Österåsen to increase the amount of information about the grey seals food preferences.</p><p>The knowledge of the grey seals diet in the Baltic Sea is today limited and few similar study’s have earlier been made. The collected scats and otoliths in this project are therefore unique.</p><p>2008:Bi 2</p>

Övergödning utgör ett av de allvarligaste hoten mot Östersjöns miljö. Storleken av näringsbelastningen till havet behöver därför bestämmas med hjälp av tillgängliga matematiska modeller. Modellen ”Generalised Watershed Loading Functions” (GWLF), en ickedistribuerad parametermodell som uppskattar hydrologi och månatlig näringsbelastning, tillämpades på avrinningsområdet till Daugava som mynnar i Östersjön. Syftet med studien var att genom modellering av historisk transport av näringsämnen till Östersjön ta fram parametrar och indata som sedan kan användas vid applicering av GWLF på omkringliggande avrinningsområden. Data från 1990-talet användes för kalibrering av modellen och data från 1980-talet för validering. Årlig kvävebelastning modellerades med R2värdet 0,78 för kalibreringsperioden. Modellerad årlig kvävebelastning för valideringsperioden underskattades med ungefär 30 % vilket troligen beror på att kvävekoncentrationer i grundvatten och ytavrinning minskade mellan 1980- och 1990-talen. Fosforbelastningen underskattades jämfört med rapporterade värden vilket troligen beror på att enskilda avlopp inte inkluderades och att rapporterade punktutsläpp är för låga. Modifikationer av modellen föreslås för prediktion av näringsbelastningar under lång tid och behovet av harmoniserad, uppdaterad och lättillgänglig data för näringstransportsmodellering diskuteras. / Eutrophication is one of the most serious threats to the Baltic Sea environment. Nutrient loading into the sea therefore needs to be quantified by available mathematical models. The Generalised Watershed Loading Functions (GWLF), a lumpedparameter model that predicts hydrology and monthly nutrient loads, was applied to the Daugava River Basin, discharging into the Baltic Sea. The aim of the study was to model historic transport of nutrients into the Baltic Sea and thereby produce estimates of parameters and input data needed for a spatial extension of the GWLF to surrounding river basins. Calibration data were taken from the 1990’s and validation data from the 1980’s. Yearly nitrogen loads were modelled with an R2 value of 0.78 for the calibration period. Predicted yearly nitrogen loads for the validation period were about 30 % lower than reported values, probably depending on decreasing groundwater and runoff concentrations between the 1980’s and 1990’s. Phosphorus loads were underestimated compared to reported values, the main reason probably being the exclusion of septic systems and too low reported point sources. Modifications of the model are suggested for longterm predictions of nutrient loads and the need for harmonised, uptodate and generally accessible data for nutrient transport modelling discussed.

No description available.

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.

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.