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Lichens are sensitive organisms widely used for environmental biomonitoring. Urban environments have been under heavy pollution, especially sulphur dioxide and nitrogen oxides, due to human activity which has led to the disappearance of lichens in city centres. Regulations and technological changes have led to cleaner air and less deposition of pollutants, especially sulphur dioxide on the vegetation in both rural and urban areas. This in turn has led to recolonization of lichens in former lichen deserted areas. In this study epiphytic macrolichens on park maples were surveyed using simple tree-based random sampling in three parks in Helsinki, and in one park in Loviisa, Siuntio and Raasepori each. The sampling and surveying methods were selected based on the SFS standard “Ambient air. Biomonitoring with lichens. Assessing epiphytic lichen diversity”. Species identification took place on site and in Botanical museum (Finnish Museum of Natural History). The results from parks in Helsinki were used to estimate if lichens have recolonized the trees. In addition, the results from the other Uusimaa municipalities were used to assess how different is the lichen species assemblage when comparing the relatively more polluted region of Helsinki to the less polluted regions in Uusimaa. The study found that pollution levels in Helsinki have declined enough to enable recolonization, of which there have been signs already in 1990s and 2000. The study used lichen diversity value of defined functional groups as one of the statistical methods which gave new information about how the species tolerance or sensitivity to pollutants shapes the recolonization. Comparison between the study areas in Uusimaa region revealed that concentrations of nitrogen oxides steer lichen species assemblage in Helsinki. Lichen surveys in Helsinki are scarce. This study brings topical information about the lichen situation in Helsinki, and it uses an as yet relatively unknown method to extract information from lichen assemblage. Regular, comparable lichen surveys are needed to further research the pressure that human activities cause on urban nature. Such time series would help to monitor both the urban nature loss and the impact of climate change on the urban nature.

Marine debris is a problem that also affects sea birds. Several bird species are known to utilise marine debris among their nest materials in different parts of the world. Debris in nests can cause entanglement and increase the risk of debris ingestion, and hazardous substances leaching from plastics can have negative effects on birds. There are also anecdotal observations of debris in the great cormorant (Phalacrocorax carbo sinensis) nests in the Gulf of Finland, however, systematic studies are lacking. In this Master’s thesis I examined the prevalence of debris in cormorant nests in the Gulf of Finland, focusing mainly on plastic debris. The study was carried out in four nesting islets, which were located in Kotka, Porvoo, Espoo and Kirkkonummi. The sampling took place in autumn 2021. 50 nests were randomly sampled on each nesting islet, and plastic debris in the nest was counted and classified according to their type, colour and origin. Plastic debris was further categorized in the laboratory according to their polymer type using Fourier Transform Infrared spectroscopy (FTIR). Debris from the nesting islets was also counted and classified according to their type, colour and origin. In total, 58% of the nests contained debris, but the prevalence of debris in the nests varied between the colonies; In Kirkkonummi debris was found in 92% of the nests while in Porvoo only 34% of the nests included debris. Plastics constituted great majority of nest debris (95%). Most common source for plastic debris was consumers, most common plastic type threadlike and polymer type polyethylene (PE). The number of debris in the nests was linked to the width and location of the nests: core nests contained more debris than periphery nests and the number of debris in the nest was positively correlated with the width of the nest. The amount of threadlike plastics in the nests was higher than that in the surrounding environment, indicating active selection by cormorants for threadlike debris types as nest material. Based on the results of this thesis, nest surveys could be a useful tool in evaluating the effectiveness of certain reduction measures aiming to tackle marine plastic pollution.

Kv7.1 is a potassium ion channel comprised of the KCNQ1 protein, which can coassemble with distinct β-subunits modulating the channel functions in different tissues. In 2017, Raivio’s group (from the University of Helsinki) found two missense mutations in the KCNQ1 gene, p.(Arg116Leu) and p.(Pro369Leu), responsible for causing pituitary hormone deficiency and maternally inherited gingival fibromatosis. The facial features and bone structure pointed to a cranial neural crest (CNC)-derived phenotype caused by an alteration in the potassium channel balance, given that these cells form the bone and cartilage of the cranial zone. To understand the implication of the CNC in the KCNQ1 syndrome, I attempted to replicate the CNC differentiation protocol of Suga and Furue (2019) with the aim of obtaining cranial neural crest cells (CNCCs). This would enable future generation of a KCNQ1-related disease model. The differentiation process was carried out thrice, and two BMP4 concentrations (10 and 100 ng/ml) were assayed. The differentiated cells exhibited a CNC-like morphology as well as upregulation of the marker genes (TFAP2A, SOX10, DLX1, MSX1, and DLX2) associated to this cell lineage. However, the gene expression was low according to the qRT-PCR Ct values, which were in most cases higher than 30. Additionally, no differences were found between the two BMP4 treatments. Furthermore, the cells did not express KCNQ1, and thus the impact of the two KCNQ1 mutations was not investigated under this protocol. In conclusion, the protocol had a low efficiency in the generation of CNCCs that was not improved by increasing the BMP4 concentration. Further optimization of the protocol, such as the BMP4 concentration or the cell density of the culture, will be needed to improve its efficiency and obtain an adequate disease model.

My master’s thesis aims to determine the effect of salinity on phytoplankton traits related to nutrient acquisition, and particularly how this interacts with resource availability. Salinity is an important driver structuring phytoplankton communities in the Baltic Sea. Salinity can also influence nutrient uptake by increasing metabolic rates required for osmotic adjustment. Thus, interaction between salinity and nutrient availability is expected to change community structure by altering phytoplankton traits determining resource competition. This is a particularly relevant area of study for the Baltic Sea due to predicted future freshening of the sea’s upper layer. We performed a microcosm experiment using artificial communities of 10 diverse phytoplankton species grown under different combinations of salinity (0, 5, 12 and 24), Nitrogen to Phosphorus molar ratio (N:P ratio = 2, 10, 16 and 80) and light (10 and 130 µmol photon m-2 s-1) conditions. A three-way interaction among these environmental parameters influenced phytoplankton traits associated with resource competition, as well as the presence and proportions of phytoplankton taxa. Light limitation inhibited community growth under all salinity conditions, but allowed diatom Phaeodactylum tricornutum to dominate. Community growth rate was higher under high light, but also more variable between salinity conditions. The strongest negative effects of nutrient limitation (N, P, and both nutrients together), both on growth rate and taxonomic diversity, were observed in the highest salinity treatment. In the freshwater treatment with the highest proportion of green algae Monoraphidium sp., N-limitation did not inhibit phytoplankton community growth and P-limitation had a more profound negative effect on community performance. Decreasing salinity appeared to decrease community C:N and C:P ratios. This shift is in opposition to the increasing C:N and C:P predicted as a consequence of other climate change-related drivers. Our results emphasise the importance of a trade-off between salinity and resource limitation in functioning of phytoplankton communities and suggest that future freshening of the Baltic Sea is likely to modify phytoplankton community composition and performance.

Climate change causes changes in the Arctic lakes, such as shortening of the ice-covered period and changes in hydrology as well as vegetation of the drainage area around the lakes. With these shifts in the function of the ecosystems, dissolved organic matter drainage from terrestrial sources is expected to increase. Terrestrial, allochthonous DOM is more refractory, higher molecular weight organic matter, which is less available to bacterial consumption. Alterations in the DOM pool of the lake may change the bacterial community composition, which could in turn alter the lake ecosystem. Four ice-covered lakes in Kilpisjärvi region were sampled in spring 2021. Water samples were filtered and analyzed for dissolved and particulate nutrients and carbon. Coloured dissolved organic matter and fluorescent dissolved organic matter properties were defined. Bacterial community composition was determined with multiplex polymerase chain reaction and sequences analyzed with DADA2 pipeline. Principal component analysis (PCOA) was done to visualize differences between lakes, and distance-based redundancy analysis (dbRDA) was used to detect any associations between dissolved organic matter properties and bacterial community composition. The lakes had low nutrient and carbon concentrations and had mainly similar properties of dissolved organic matter. However, P3 surface water had higher nitrate and total dissolved nitrogen concentrations. Optical properties in P3 surface water, Peak T, Peak M, biological index and humification index, indicated autochthonous production and lability of organic matter. This was reflected also in bacterial community composition by higher relative abundance of Gammaproteobacteriales. Lake P3 had also higher relative abundance of Cyanobacteria, which could be the cause for labile organic matter in the site. Sites P2 and P3 had similar bacterial community compositions, which is likely due to the sites forming a lake chain and sharing the same catchment area. The sites were oligotrophic and low nutrient environments as expected in the arctic environment. One of the sites had indications of more labile organic matter, which was reflected in the bacterial community structures. In the future shorter ice-cover period may induce autochthonous production such as Cyanobacteria, which reflects in the bacterial community. Changes in the DOM properties and bacterial communities can alter the whole food chain. with A more comprehensive study on this issue could be useful way of understanding the carbon cycling and impacts of climate change to the subarctic lakes.

Light is crucial for aquatic ecosystems, as photosynthesis supports the higher trophic levels. Light attenuates in water due to absorption and scattering by optically active substances (OAS), the main ones in coastal environments being chlorophyll-a (chl-a), particulate matter and coloured dissolved organic matter (CDOM). Light attenuation measurements are also important indicators of many environmental changes. Traditionally, Secchi depth has been used to monitor changes in light attenuation. However, Secchi depth (ZS) is a not an accurate estimate of light attenuation, and conversion to light attenuation coefficient (Kd) is needed to study light conditions as aquatic organisms observe them. Therefore, calibration between methods is important. In this study, light attenuation was estimated with Secchi disc, a light meter and light loggers to scrutinize the possibilities of autonomous measurements in this context. The aims of the study were 1) to compare three methods for estimating light attenuation and 2) to identify the environmental drivers affecting the relationships and accuracy of these methods, and 3) to assess the possibility of using conductivity as a proxy for light attenuation. The main hypotheses were that the differences in conversion between ZS and the two sensor-based methods in different concentrations of optically active substances can be explained by contribution of scattering to light attenuation, and that variation in different Kd-estimates is due to the different measurement spectra. The effect of three OASs (chl-a, particulate matter, CDOM) on differences among light attenuation estimates were quantified in Pohjanpitäjänlahti bay. Light attenuation was mainly controlled by CDOM, followed by particulate matter and chl-a. Conductivity was found to be a good proxy for light attenuation. However, there was a mixed signal if the differences among methods could be explained by OAS concentrations or conductivity, as the hypotheses were supported with one device pair but not with the other. Therefore, the differences among light measurement methods might stem from the characteristics of the devices or measurement errors. However, all the methods were found suitable for tracking changes in light attenuation and a summary table of the advantages and disadvantages of each method is presented to help choose a suitable method to estimate light attenuation e.g., in future studies or environmental monitoring.

Eläinten tunnemaailma on meille melko vieras. Sen takia on tärkeää tutkia, millaiset asiat vaikuttavat siihen, miten tulkitsemme niiden tunteita. Tunteiden tulkintaan voivat vaikuttaa tulkitsijan omat kokemukset. Tämän tutkielman tarkoituksena on tutkia sitä, mitkä asiat vaikuttavat siihen, kuinka hyvin eläintarhakävijät tunnistavat villieläinten tunteita. Erityisesti keskityn siihen, miten vastaajan sukupuoli, ikä, kasvuympäristö ja lapsuuden ja aikuisuuden aikaiset eläinkokemukset vaikuttavat eläintarhakävijöiden kykyyn tunnistaa eläinten tunteita. Tutkimus tehtiin kyselytutkimuksena Korkeasaaren eläintarhassa kesällä 2021. Osallistujille näytettiin videolta eläin ja heidän tuli kertoa, onko eläimen tunnetila neutraali, myönteinen vai kielteinen ja onko se rauhallinen vai kiihtynyt. Tutkimuksessa tutkittiin tiikereiden, berberiapinoiden ja markhorvuohien tunnetilan tunnistamista. Osallistujista kerättiin taustatietoja, kuten ikä ja sukupuoli. Tulosteni perusteella eläinlajilla on vaikutusta tunnetilan tunnistamiseen. Tiikerin myönteisyys tai kielteisyys osattiin arvioida huonommin kuin berberiapinan. Myös vastaajan ikä vaikuttaa tunteiden tunnistukseen. Vanhemmat tunnistivat myönteisyyden tai kielteisyyden nuorempia ihmisiä heikommin. Sukupuoli vaikuttaa yhdessä iän kanssa kiihtyneisyyden tunnistamiseen. Kiihtyneisyyden tunnistivat paremmin 18–30-vuotiaat naiset kuin 61–75-vuotiaat naiset, mutta muiden ryhmien välillä ei havaittu merkitseviä eroja. Kiihtyneisyys tunnistettiin myös paremmin, jos eläimet ovat olleet osana vastaajan elämää vain lapsuudessa sen sijaan, että ne olisivat olleet aina osana elämää. Tulosten perusteella voidaan päätellä, että ihmiset tunnistavat eri eläinten tunteet eri tavalla ja ihmismäisempien eläinten tunteet ovat muita helpommin tunnistettavissa. Iällä ja sukupuolella voi olla vaikutusta ihmisten kykyyn tunnistaa eläinten tunteita. Myös eläinkokemus vaikuttaa ihmisten kykyyn tunnistaa tunteita ja kokemus ei ole sama kuin tiedon omaksuminen. Tuloksiani voidaan hyödyntää esimerkiksi ympäristökasvatuksessa.

Kiihtyvän ilmastonmuutoksen aikana on entistä tärkeämpää löytää tapoja vähentää päästöjä ja sitoa hiiltä. Biohiilen käyttö on yksi keino ilmastonmuutoksen hillitsemiseen, ja sillä on potentiaalia parantaa maatalouden satoja. Ennen kuin biohiilen käyttö voi yleistyä, sen mahdolliset ulkoisvaikutukset, kuten vaikutukset maaperän eliöstöön, on kuitenkin ensin selvitettävä. Tässä opinnäytetyössä tutkittiin biohiilen käytön vaikutuksia mikrobien suhteelliseen runsauteen, kastematoyhteisöihin ja mikrobibiomassaan. Vain lauhkean ja boreaalisen vyöhykkeen kenttätutkimukset olivat osana tutkimusta. Biohiilen vaikutukset mikrobiryhmien suhteelliseen määrään selvitettiin kirjallisuuskatsauksella. Kirjallisuuskatsaus tehtiin myös selvittäessä biohiilen vaikutuksia kastematoihin. Biohiilen vaikutukset mikrobibiomassaan selvitettiin meta-analyysillä. Meta-analyysissä käytetyt tutkimukset luokiteltiin muuttujien, kuten biohiilen raaka-aineen, pyrolyysilämpötilan, maaperän pH:n, SOC:n, maaperän rakenteen ja biohiilen levitysmäärän perusteella. Tätä kautta voitiin selvittää, voisiko jokin näistä muuttujista selittää meta-analyysin tulokset. Mikrobien suhteellisen runsauden havaittiin muuttuvan biohiilen lisäyksen myötä, mutta reagoivat organismiryhmät vaihtelivat suuresti ja vaikutus yleensä haihtui ajan myötä. Biohiilen lisääminen ei vaikuttanut kastematoihin merkittävästi. Meta-analyysien tulokset viittaavat siihen, että biohiilellä ei myöskään ole merkittävää vaikutusta mikrobien kokonaisbiomassaan. Eri muuttujilla tehdyt meta-analyysit viittaavat siihen, että biohiilen lisäyksellä on positiivisin vaikutus mikrobien biomassaan happamissa maaperissä, joissa on karkea rakenne ja korkea SOC-pitoisuus, kun biohiiltä tuotetaan 500 °C–700 °C:ssa ja levitetään määrinä, jotka ovat suurempia tai yhtä suuri kuin 30 t ha-1. Biohiilen raaka-aineella ei havaittu olevan merkittävää vaikutusta. Yhteenvetona voidaan todeta, että mikrobi- ja kastematoyhteisöt pysyvät yleensä vakaina biohiiltä käytettäessä. Tämä mahdollistaisi biohiilen käytön mm. hiilen sitomiseen ja maaperän hedelmällisyyden lisäämiseen maaperän eliöstöä vahingoittamatta. Lisätutkimusta kaivataan kuitenkin erityisesti boreaalisilla alueilla sekä biohiilen ja pääviljelykasvin mahdollisista vuorovaikutuksista. Tutkia kannattaisi myös mahdollisuuksia käyttää biohiiltä yhdessä muiden orgaanisten käsittelyjen, kuten lannan tai kompostin kanssa biologisen monimuotoisuuden ja sadon parantamiseksi.

Climate change is expected to cause salinity change in the Baltic Sea and therefore may affect organisms living in the Baltic such as plankton. The microbial loop is an important part of the plankton food web. It consists of heterotrophic bacteria, nanoflagellates and ciliates and is connected with the classic plankton food chain through interactions with primary producers and mesozooplankton. Therefore, salinity affects the functioning of the microbial food web not only directly, but also through salinity induced changes on primary producers and mesozooplankton. In this master’s thesis I studied the effects of salinity change on microbial loop components bacteria, nanoflagellates and ciliates in an outdoor mesocosm experiment containing four salinity treatments with salinities of 3.5, 5.5, 7.5 and 9.5, three replicas each. The experiment took place offshore at the Tvärminne Zoological Station. Bacteria were sampled from the mesocosms every other day and nanoflagellates and ciliates every 6th day. Bacteria were analysed with the flow cytometer, nanoflagellates with epifluorescent microscopy and ciliates using an inverted microscope. The effects of salinity on microbial loop components were statistically tested using linear mixed effects models. Results of the experiment show that salinity had an indirect effect on microbial loop components through changes in mesozooplankton composition. There were significant differences between high and low salinity treatments in bacteria abundance and composition, the interaction strength between HNFs and bacteria and in the mean cell size of ciliate communities. These were mainly caused by differences in mesozooplankton community structure between salinity treatments, which had cascading effects on the strength of top-down and bottom-up control on the trophic levels of the microbial loop, leading to changes in bacteria abundances and composition. Based on the results of this thesis, more studies are needed to detect the effects that changes in the composition and functioning of the microbial loop might have on the ecosystem. Further research should also focus on the significance of the structure and diversity of the communities within the microbial loop as well as the functional roles of different species in the microbial food web.

Mercury (Hg) is a heavy metal acknowledged as a worldwide contaminant that accumulates in organisms and biomagnifies in food webs. The organic methylmercury (MeHg) species is harmful to animals, including humans, and mainly derived from the diet. The dietary Hg consumed by fish is mostly removed through the intestine, but some of the MeHg bioaccumulates, especially in the white muscle tissue of fish. Perch (Perca fluviatilis) and roach (Rutilus rutilus) are commonly found fish species in Finland. Perch has additional im-portance as it is the national fish of Finland, a popular food fish, as well as a monitoring species used to evaluate the chemical status of lakes. Seasonal variation of Hg in muscle tissue of fish is supposedly caused by starvation in winter, which condenses Hg in the muscle, and growth dilution in summer, which refers to fast somatic growth during the growing season, which dilutes Hg in the muscle. Similar to winter, spawning has also been found to condense Hg in muscle tissue of fish due to high energy investment into gonad development. Seasonal variation of Hg and variables driving seasonal changes have been shown to differ between fish species. Seasonal variation has been studied mainly during the open-water season. However, less is known about how winter conditions under ice affect Hg levels in fish. In this MSc thesis, I asked (Q1) How total mercury (THg) content in the muscle tissue of perch and roach change annually? (Q2) How THg bioaccumulation in the muscle tissue of perch and roach change annually? (Q3) What are the factors explaining annual variation in THg content in the muscle tissue of perch and roach? The practical application of results was to discuss if annual variation should be considered in monitoring programs and human health questions. The materials used in this study were collected from Lake Pääjärvi monthly from March 2020 to March 2021. Fish were collected using gillnet series. Length, weight, sex, sexual maturity, stomach fullness, Fulton’s condition factor (K), and muscle THg were determined from each fish. The annual length-corrected THg content variation was tested using analysis of variance. The annual THg bioaccumulation variation in the relationship between muscle and fish length was tested using simple linear regression analysis, and the seasonal variation in THg bioaccumulation was tested with LOESS regression analysis. Variables affecting seasonal variation were tested with stepwise multiple linear regression analysis. THg content of perch was the highest in winter and spring and the lowest in fall, while roach showed no significant seasonal variation. THg bioaccumulation of both species was highest in winter, spring, and early summer and lowest in fall. Perch displayed more substantial seasonal variation than roach. Biological and environmental variables that explained the THg content of perch were length, ice thickness, gonadosomatic index (GSI), light, and condition factor. Variables that explained the THg content of roach were length, sex, and total phosphorus (Tot-P). This study confirmed that starvation in winter, growth dilution in summer, and spawning in spring/early summer are vital factors driving seasonal variation. Due to evident seasonal variation, monitoring month should be pre-set in current monitoring programs.