From the river to the open sea - a critical life phase of young Atlantic salmon migrating from the Simojoki river

Long-term monitoring data collected from wild smolts of Atlantic salmon (Salmo salar) in the Simojoki river, northern Finland, were used in studying the relationships between the smolt size and age, smolt and postsmolt migration, environmental conditions and postsmolt survival. The onset of the smolt run was significantly dependent on the rising water temperature and decreasing discharge of the river in the spring. The mean length of smolts migrating early in the season was commonly higher and the mean age always older than among smolts migrating later. Many of the smolts migrating early in the season and almost all smolts migrating later had started their new growth in spring in the river before their sea entry. Among postsmolts, the time required for emigration from the estuary was dependent on the sea surface temperature (SST) off the river, being significantly shorter in years with warm than cold sea temperatures. After leaving the estuary, the postsmolts migrated southwards along the eastern coast of the northern Gulf of Bothnia, the geographical distribution of the tag recoveries coinciding with the warm thermal zone in spring in the coastal area. After arriving in the southern Gulf of Bothnia in late summer the postsmolts mostly migrated near the western coast, reaching the Baltic Main Basin in late autumn. Until the early 1990s there was only a weak positive association between smolt length and postsmolt survival. However, following a subsequent decrease in the mean smolt size, a significant positive dependence was observed between smolt size and the reported recapture rate of tagged salmon. The differences in recapture rates between smolts tagged during the first and second half of the annual migration season were insignificant, indicating that the seasonal variation in smolt size and age seem to be too small to affect survival. Among the climatic factors examined, the summer SST in the Gulf of Bothnia was most clearly related to the survival of the wild postsmolts. Postsmolt survival appeared to be highest in years when the SST in June in the Bothnian Bay varied between 9 and 12 ºC. In addition, the survival of wild postsmolts showed a significant positive dependence on the SST in July in the Bothnian Sea, but not on the abundance of the prey fish (0+ herring, Clupea harengus and sprat, Sprattus sprattus) in the Bothnian Sea and in the Baltic Main Basin. The results suggest, that if the incidence of extreme weather conditions were to increase due to climatic changes, it would probably reduce the postsmolt survival of wild salmon populations. For improving the performance of hatchery-reared smolts, it could be useful to examine opportunities to produce smolts that are in their smolt traits and abilities more similar to the wild smolts described in this thesis.

Environmental factors and uncertainty in fisheries management in the northern Baltic Sea

The Baltic Sea is a geologically young, large brackish water basin, and few of the species living there have fully adapted to its special conditions. Many of the species live on the edge of their distribution range in terms of one or more environmental variables such as salinity or temperature. Environmental fluctuations are know to cause fluctuations in populations abundance, and this effect is especially strong near the edges of the distribution range, where even small changes in an environmental variable can be critical to the success of a species. This thesis examines which environmental factors are the most important in relation to the success of various commercially exploited fish species in the northern Baltic Sea. It also examines the uncertainties related to fish stocks current and potential status as well as to their relationship with their environment. The aim is to quantify the uncertainties related to fisheries and environmental management, to find potential management strategies that can be used to reduce uncertainty in management results and to develop methodology related to uncertainty estimation in natural resources management. Bayesian statistical methods are utilized due to their ability to treat uncertainty explicitly in all parts of the statistical model. The results show that uncertainty about important parameters of even the most intensively studied fish species such as salmon (Salmo salar L.) and Baltic herring (Clupea harengus membras L.) is large. On the other hand, management approaches that reduce uncertainty can be found. These include utilising information about ecological similarity of fish stocks and species, and using management variables that are directly related to stock parameters that can be measured easily and without extrapolations or assumptions.

Antipredator behaviour of Baltic planktivores

Predation is an important source of mortality for most aquatic animals. Thus, the ability to avoid being eaten brings substantial fitness benefits to individuals. Predator detection abilities and antipredator behaviour were examined in various planktivores, i.e. the littoral mysids Neomysis integer and Praunus flexuosus, three-spined stickleback Gasterosteus aculeatus larvae, pelagic mysids Mysis mixta and M. relicta, and the predatory cladoceran Cercopagis pengoi, with cues from their respective predators European perch Perca fluviatilis and Baltic herring Clupea harengus membras. The use of different aquatic macrophytes as predation refuges by the littoral planktivores was also examined. All pelagic planktivores and stickleback larvae were able to detect the presence of their predator by chemical cues alone. The littoral mysids N. integer and P. flexuosus responded only when chemical and visual predator cues were combined. The responses of stickleback larvae were stronger to the combined cues than the chemical cue alone. A common antipredator behaviour in all of the planktivores studied was decreased ingestion rate in response to predator cues. N. integer and stickleback larvae also decreased their swimming activity. Pelagic mysids and C. pengoi altered their prey selectivity patterns in response to predator cues. The effects of predator cues on the swarming behaviour of N. integer were examined. Swarming brings clear antipredator advantages to N. integer, since when they feed in a swarm, they do not significantly decrease their feeding rate. However, the swarming behaviour of N. integer was not affected by predation risk, but was instead a fixed strategy. Despite the presence or absence of predator cues, N. integer individuals attempted to associate with a swarm and preferred larger to smaller swarms. In studies with aquatic macrophytes, stickleback larvae and P. flexuosus utilized vegetation as a predation refuge, spending more time within vegetation when under predation threat. The two macroalgal species studied, bladderwrack Fucus vesiculosus and stonewort Chara tomentosa, were preferred by P. flexuosus, whereas Eurasian watermilfoil Myriophyllum spicatum was strongly avoided by N. integer and stickleback larvae. In fact, when in dense patches in aquaria, M. spicatum caused acute and high mortality (> 70%) in littoral mysids, but not in sticklebacks, whereas C. tomentosa and northern watermilfoil M. sibiricum did not. In contrast, only 2-4% mortality in N. integer was observed with intact and broken stems of M. spicatum in field experiments. The distribution of littoral mysids in different vegetations, however, suggests that N. integer avoids areas vegetated by M. spicatum.

Molecular Tuning of Rhodopsins for High Visual Sensitivity in Different Light Environments : Variation in Absorbance Spectrum and Opsin Sequence within and between Species

Visual pigments of different animal species must have evolved at some stage to match the prevailing light environments, since all visual functions depend on their ability to absorb available photons and transduce the event into a reliable neural signal. There is a large literature on correlation between the light environment and spectral sensitivity between different fish species. However, little work has been done on evolutionary adaptation between separated populations within species. More generally, little is known about the rate of evolutionary adaptation to changing spectral environments. The objective of this thesis is to illuminate the constraints under which the evolutionary tuning of visual pigments works as evident in: scope, tempo, available molecular routes, and signal/noise trade-offs. Aquatic environments offer Nature s own laboratories for research on visual pigment properties, as naturally occurring light environments offer an enormous range of variation in both spectral composition and intensity. The present thesis focuses on the visual pigments that serve dim-light vision in two groups of model species, teleost fishes and mysid crustaceans. The geographical emphasis is in the brackish Baltic Sea area with its well-known postglacial isolation history and its aquatic fauna of both marine and fresh-water origin. The absorbance spectrum of the (single) dim-light visual pigment were recorded by microspectrophotometry (MSP) in single rods of 26 fish species and single rhabdoms of 8 opossum shrimp populations of the genus Mysis inhabiting marine, brackish or freshwater environments. Additionally, spectral sensitivity was determined from six Mysis populations by electroretinogram (ERG) recording. The rod opsin gene was sequenced in individuals of four allopatric populations of the sand goby (Pomatoschistus minutus). Rod opsins of two other goby species were investigated as outgroups for comparison. Rod absorbance spectra of the Baltic subspecies or populations of the primarily marine species herring (Clupea harengus membras), sand goby (P. minutus), and flounder (Platichthys flesus) were long-wavelength-shifted compared to their marine populations. The spectral shifts are consistent with adaptation for improved quantum catch (QC) as well as improved signal-to-noise ratio (SNR) of vision in the Baltic light environment. Since the chromophore of the pigment was pure A1 in all cases, this has apparently been achieved by evolutionary tuning of the opsin visual pigment. By contrast, no opsin-based differences were evident between lake and sea populations of species of fresh-water origin, which can tune their pigment by varying chromophore ratios. A more detailed analysis of differences in absorbance spectra and opsin sequence between and within populations was conducted using the sand goby as model species. Four allopatric populations from the Baltic Sea (B), Swedish west coast (S), English Channel (E), and Adriatic Sea (A) were examined. Rod absorbance spectra, characterized by the wavelength of maximum absorbance (λmax), differed between populations and correlated with differences in the spectral light transmission of the respective water bodies. The greatest λmax shift as well as the greatest opsin sequence difference was between the Baltic and the Adriatic populations. The significant within-population variation of the Baltic λmax values (506-511 nm) was analyzed on the level of individuals and was shown to correlate well with opsin sequence substitutions. The sequences of individuals with λmax at shorter wavelengths were identical to that of the Swedish population, whereas those with λmax at longer wavelengths additionally had substitution F261F/Y in the sixth transmembrane helix of the protein. This substitution (Y261) was also present in the Baltic common gobies and is known to redshift spectra. The tuning mechanism of the long-wavelength type Baltic sand gobies is assumed to be the co-expression of F261 and Y261 in all rods to produce ≈ 5 nm redshift. The polymorphism of the Baltic sand goby population possibly indicates ambiguous selection pressures in the Baltic Sea. The visual pigments of all lake populations of the opossum shrimp (Mysis relicta) were red-shifted by 25 nm compared with all Baltic Sea populations. This is calculated to confer a significant advantage in both QC and SNR in many humus-rich lakes with reddish water. Since only A2 chromophore was present, the differences obviously reflect evolutionary tuning of the visual protein, the opsin. The changes have occurred within the ca. 9000 years that the lakes have been isolated from the Sea after the most recent glaciation. At present, it seems that the mechanism explaining the spectral differences between lake and sea populations is not an amino acid substitution at any other conventional tuning site, but the mechanism is yet to be found.

Archaeology of wings : Birds and people in the Baltic Sea region during the Stone Age

The prominent roles of birds, often mentioned in historical sources, are not well reflected in archaeological research. Absence or scarcity of bird bones in archaeological assemblages has been often seen as indication of a minor role of birds in the prehistoric economy or ideology, or explained by taphonomic loss. Few studies exist where birds form the basis for extensive archaeological interpretation. In this doctoral dissertation bird bone material from various Stone Age sites in the Baltic Sea region is investigated. The study period is approximately 7000-3400 BP, comprising mainly Neolithic cultures. The settlement material comes from Finland, Åland, Gotland, Saaremaa and Hiiumaa. Osteological materials are used for studying the economic and cultural importance of birds, fowling methods and principal fowling seasons. The bones were identified and earlier identifications partially checked with help of a reference material of modern skeletons. Fracture analysis was used in order to study the deposition history of bones at Ajvide settlement site. Birds in burials at two large cemeteries, Ajvide on Gotland and Zvejnieki in northern Latvia were investigated in order to study the roles of birds in burial practices. My study reveals that the economic importance of birds is at least seasonally often more prominent than usually thought, and varies greatly in different areas. Fowling has been most important in coastal areas, and especially during the breeding season. Waterbirds and grouse species were generally the most important groups in Finnish Stone Age economy. The identified species composition shows much resemblance to contemporary hunting with species such as the mallard and capercaillie commonly found. Burial materials and additional archaeological evidence from Gotland, Latvia and some other parts of northern Europe indicate that birds –e.g., jay, whooper swan, ducks – have been socially and ideologically important for the studied groups (indicating a place in the belief system, e.g. clan totemism). The burial finds indicate that some common ideas about waterbirds (perhaps as messengers or spirit helpers) might have existed in the northern European Stone Age.

Death, Destruction and Commemoration : Tracing ritual activities in Finnish Late Iron Age cemeteries (AD 550-1150)

The thesis is connected with death, memory and ancestor commemoration during the Merovingian Period, the Viking Age and the beginning of the Crusade Period (AD 550-1150) in Finland. During this time, cremation was the dominant burial rite. It was not until the end of the Viking Age that inhumation became more common but both cremations and inhumations are performed even at the same sites throughout the time. Three different burial types 1) cremation cemeteries below level ground, 2) inhumation burials and 3) water burials are discussed in five articles. I consider these burial forms from three different viewpoints; collectivity-individuality, visibility-invisibility and cremation-inhumation. The thesis also discusses the topics of memory, memorialisation and monument re-use, which have been neglected subjects in Finnish archaeology until now. Both cremation cemeteries below level ground and inhumation burials have been re-used during their time of usage, and on most occasions are situated in a landscape that is overlaid by other monuments as well. The main questions of the thesis are: What kinds of ritual behaviour can we detect in the burials during the period (AD 550-1150)? How did people perceive the moraine hills that functioned as burial places? What kind of re-use can be detected in the Iron Age cemeteries? Why have ancient sites and artefacts been re-used? This thesis shows that it is possible to claim that both artefact and site re-use is a much more widespread phenomenon than has previously been thought in Finnish archaeology. It is also a conscious and deliberate behaviour that can be related to an ancestor cult and commemoration of the dead. The funerary rituals during this time period show great variation and complex, both regionally and nationally. Not only have the dead been buried using elaborate rituals, they have also been mourned and commemorated in intricate ways that proves that death was not an end product, but the start of something new.

Lithics after Stone Age in East Africa : Wadh Lang'o case study

Tutkielmassa käsitellään kiviesineiden käytön jatkumista kivikauden jälkeen Itä-Afrikassa. Rautakauden alku Itä- ja Etelä-Afrikassa liitetään perinteisesti bantuheimojen migraatioon näille alueille. Tämä vallitseva teoria otettiin tässä tutkimuksessa lähtökohdaksi. Afrikasta tunnetaan runsaasti sekä etnografisia että arkeologisia esimerkkejä kiviteknologian säilymisestä paikoin 1900-luvun loppupuolelle. Nämä liittyvät usein perimätiedon perusteella "kivikautisten" metsästäjä-keräilijöiden ja rautakautisten maanviljelijä- ja karjanhoitajayhteisöjen rinnakkaiseloon. Tutkimuskysymystä lähestytään sekä julkaistun että primääriaineiston kautta. Alussa esitellään kirjallisuudesta löytyviä esimerkkejä myöhäisestä kiviesineiden käytöstä, minkä jälkeen käydään tarkemmin läpi Malawin alueelta julkaistu aiheeseen liitettävissä oleva arkeologinen aineisto. Tätä käytetään vertailuaineistona tutkimuksen pääasiallista tapaustutkimusta käsiteltäessä. Pääasiallisena tapaustutkimuksena toimii Viktoria-järven läheisyydessä sijaitsevan Wadh Lang'o:n asuinpaikan kiviesineistön analyysi. Wadh Lang'o:sta tunnetaan pitkä kulttuurisekvenssi, joka kattaa alueen myöhäiskivikautiset ja rautakautiset kulttuurivaiheet. Stratigrafisen aineiston perusteella kiviesineet ovat säilyneet asuinpaikalla käytössä ainakin keskisen rautakauden alkuun. Varhaisimmassa vaiheessa asuinpaikkaa on asuttanut Oltome-kulttuuriin kuuluva väestö. Suurimmat muutokset materiaalisessa kulttuurissa analyysin kattamana aikana ovat aiheutuneet seuraavan kulttuurivaiheen, Elmenteitan-kulttuurin, myötä. Kiviesineistön perusteella Elmenteitan-keramiikan ilmaantuminen asuinpaikalle on liitettävissä idästäpäin Itä-Afrikan hautavajoaman suunnalta tapahtuneeseen migraatioon. Jatkuvuuden puolesta puhuvat esimerkiksi tehdyt kiviraaka-aine valinnat. Vaikuttaa, että edeltänyt Oltome-keraaminen väestö on säilyttänyt vaikutuksensa asuinpaikalla vielä tänäkin aikana. Varhaisrautakautisen Urewe-keramiikan ilmestymiseen asuinpaikalle ei näyttäisi olevan liitettävissä mitään suurisuuntaista migraatiota, toisin kuin vallalla oleva teoria bantumigraatiosta antaisi olettaa. Mahdollisesti uusi keramiikka on omaksuttu spesialistien, esimerkiksi seppien, muuton myötä tai vaeltavien kauppiaiden vaikutuksesta. Kiviesineistö osoittaa jatkuvuutta esimerkiksi mikroliittien morfologisten piirteiden ja käytettyjen raaka-aineiden perusteella. Mahdollisesti Elmenteitan-kulttuurin karjanhoitoa harjoittanut väestö on kyennyt estämään bantusiirtolaisten muuton alueelleen. Rauta ei vaikuta olleen asuinpaikalla missään vaiheessa erityisen yleistä, eikä paikalta tunneta merkkejä raudanvalmistuksesta. Tutkielman lopussa esitellään kaksi vaihtoehtoista mallia, joiden pohjalta myöhäinen kiviesineiden käyttö voisi selittyä. Niistä ensimmäinen perustuu konventinaaliseen käsitykseen, jossa rautakauden alku nähdään bantumigraation seurauksena. Toinen malli perustuu varhaisrautakautisten kulttuuripiirteiden leviämiseen diffuusion avulla. Wadh Lang'o:n tapaustutkimus näyttäisi puhuvan diffuusion puolesta, mutta toisilla alueilla, esimerkiksi Malawissa, migraatio vaikuttaa olevan todennäköisin selitysmalli. Avainsanat: arkeologia, kiviteknologia, Itä-Afrikka, Oltome, Elmenteitan, Urewe, bantumigraatio, myöhäiskivikausi, rautakausi

Stroke and coronary heart disease in relation to hyperglycemia gender and age

This study was carried out to compare the fasting plasma glucose (FPG) and 2-h plasma glucose (2-h PG) criteria for diabetes with regard to their relation to stroke mortality and the incidence of ischemic and hemorrhagic stroke. In addition, the age-and gender difference in the incidence of coronary heart disease (CHD) and stroke and their relation with known cardiovascular disease risk factors and diabetes mellitus was examined. The study was a sub-data analysis of the Diabetes Epidemiology: Collaborative analysis Of Diagnostic criteria in Europe (DECODE) study including 25 181 individuals, 11 844 (47%) men and 13 345 (53%) women aged 25 to 90 years, from 14 European cohorts. In individuals without a history of diabetes elevated 2-h post-challenge glucose was a better predictor of stroke mortality than elevated fasting glucose in men, whereas the latter was better than the former in women. Elevated FPG and 2-h PG levels were associated with an increased risk of ischemic stroke incidence. 2-h PG contributed to the risk more strongly than FPG. No relationship between hyperglycemia and the risk of hemorrhagic stroke was found. The risk of CHD and ischemic stroke incidence increased with age in both genders, but was higher in all age groups in men than in women. The gender difference was, however, more marked for CHD than for ischemic stroke. Age, smoking and diabetes contributed to the development of both CHD and ischemic stroke. Elevated cholesterol levels predicted CHD only, whereas elevated blood pressure was a risk predictor for the incidence of ischemic stroke. The CHD and ischemic stroke risk was higher in men than in women with and without diabetes, however, the gender difference diminished for CHD but enlarged for ischemic stroke in diabetic individuals. The known risk factors including diabetes contributed differently to the risk of CHD and ischemic stroke in women and in men. Hyperglycemia defined by FPG or 2-h PG increases the risk of ischemic stroke in individuals without diabetes. FPG better predicts stroke mortality in women and 2-h PG in men. The risk of acute CHD and ischemic stroke is higher in men than in women in all ages, but such gender difference is more marked for CHD than for ischemic stroke. CHD risk is higher in men than in women, but the difference is reduced in diabetic population. Diabetes, however, increases stroke risk more in men than in women in all ages.

Amyloid diseases at old age : a pathological, epidemiological, and genetic study

Along with the increased life span of individuals, the burden of old age-associated diseases has inevitably increased. Alzheimer s disease (AD), probably the most well known geriatric disease, belongs to the old age-associated amyloid diseases. The purpose of this study was to investigate the frequency, genetic and health-associated risk factors, mutual association, and amyloid proteins in two old age-associated amyloid disorders senile systemic amyloidosis (SSA) and cerebral amyloid angiopathy (CAA) as part of the prospective population-based Vantaa 85+ autopsy study on a Finnish population aged 85 years or more (Studies I-III), completed with a case report on a patient with advanced AGel amyloidosis (Study IV). The numbers of patients investigated in the studies (I-III) were 256, 74, and 63, respectively. The diagnosis and grading of amyloid were based upon histological examination of tissue samples obtained post mortem and stained with Congo red. The amyloid fibril and associated proteins were characterized by immunohistochemical staining methods. The genotype frequencies of 20 polymorphisms in 9 genes and information on health-associated risk factors in subjects with and without SSA and CAA were compared. In a Finnish population ≥ 95 years of age, SSA and CAA occurred in 36% and 49% of the subjects, respectively. In total, two-thirds of these very elderly individuals had SSA, CAA, or both. However, in only 14% of the population these two conditions co-occurred. In subjects 85 years or older, the prevalence of SSA was 25%. In this population, SSA was associated with age at the time of death (p=0.002), myocardial infarctions (MIs; p=0.004), the G/G (Val/Val) genotype of the exon 24 polymorphism in the alpha2-macroglobulin (α2M) gene (p=0.042) and with the H2 haplotype of the tau gene (p=0.016). In contrast, the presence of CAA was strongly associated with APOE e4 (p=0.0003), with histopathological AD (p=0.0005), and with clinical dementia (p=0.01) in both e4+ (p=0.02) and e4- (p=0.06) individuals. Apart from demonstrating the amyloid fibril proteins, complement proteins 3d (C3d) and 9 (C9) were detected in the amyloid deposits of CAA and AGel amyloidosis, and α2M protein was found in fibrous scar tissue close to SSA. In conclusion, this first population based study on SSA shows that both SSA and CAA are common in very elderly individuals. Old age, MIs, the exon 24 polymorphism of the α2M gene, and H1/H2 polymorphism of the tau gene associate with SSA while clinical dementia and APOE ε4 genotype associate with CAA. The high prevalence of CAA, combined with its association with clinical dementia independent of APOE genotype, neuropathological AD, or SSA, also highlights its clinical significance in the very aged, among which the serious end stage complications of CAA, namely multiple infarctions and hemorrhages, are rare. The report on a patient having advanced AGel amyloidosis added knowledge on the disease and showed that this generally benign condition occasionally may lead to death. Further studies are warranted to confirm the findings in other populations. Also, the role of α2M and tau in the pathogenesis of SSA and the involvement of complement in the process of amyloid beta (Aβ) protein elimination from the brain remain to be clarified. Finally, the high prevalence of SSA in the elderly raises the need for prospective clinical studies to define its clinical significance.