Browsing by Subject "diet"
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(2023)Diets of wild owls have been studied by pellets, when the nutritional value of owl prey remains unclear. Fatty acids are an essential part of animal nutrition, acting as energy reserve, building blocks of membranes and precursors for signaling molecules. I studied whether Finnish owl species have species-specific characteristics in the fatty acid profiles of adipose tissue due to different diets and feeding habits. I also compared fatty acid profiles between wild and captive owls to elucidate if the diet of captive owls resembles the diet in the wild. Fatty acids from visceral adipose tissue and a liver were transesterified to fatty acid methyl esters, which were identified and quantified by gas-chromatographs linked to either a mass spectrometry or flame ionisation detector. The fatty acid compositions were compared with Principal Component Analysis and statistical significance of the separations between species, origins and tissues were studied by Soft Independent Modelling of Class Analogies. Differences in the relative concentrations of individual fatty acids and their structural category sums were evaluated by the Kruskal-Wallis test followed by the Wilcoxon rank-sum test. Compared to wild owls, captive owl (snowy owl Bubo scandiacus and Eurasian eagle-owl Bubo bubo) adipose tissues had lower relative concentrations of many long-chain polyunsaturated fatty acids (PUFAs), such as arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid. The captive owls also had lower n-3 PUFA/n-6 PUFA ratio than the wild owls. I suggest that these differences arise from anthropogenic food given to the prey of the captive owls. In the future, the feeding and breeding of captive owls could be improved and potential health hazards prevented by giving the owls a diet rich in long-chain PUFAs, either by giving the prey more versatile diet or adding supplements to the owl’s diet. The adipose tissues of wild Eurasian eagle-owls contained higher total relative concentrations of monounsaturated fatty acids than the species belonging to the Strix genus. On the other hand, long-chain PUFAs were more prominent in the Strix owls. I suggest that these differences in the fatty acid composition are due to the disparities in feeding behaviour: the Eurasian eagle-owls eat carrions and large prey that cannot be swallowed whole, which may lead to consuming more the body outer parts of the prey. The fatty acid composition of the eagle-owls can also be affected by urban prey that have consumed anthropogenic food. In the future, the fatty acid composition of wild prey should be examined to be able to evaluate the prey composition of owls and its effect on the owl fatty acid profile with physiological consequences, the knowledge that could be used in the future decision-making that supports the conservation of owls.
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(2020)Food literacy is a noteworthy topic to be studied due to food’s considerable environmental and health effects. When food literacy and its characteristics are known, food literacy can be used as a tool to improve people’s health and the condition of the environment. Thus, this thesis aims to reveal the extent of food literacy among Finnish upper secondary school students. In this context, food literacy emphasises food-related environmental and health knowledge. Environmental knowledge is understanding of the global environmental impact of food. Health knowledge, on the other hand, is the familiarity with the relationship between excessive meat consumption and Finnish common diseases along with beliefs regarding diets and food products as a source of protein. This thesis also aims to identify to what extent does the food literacy differ based on gender, study year and living area. This study was performed as a quantitative sample survey and the data was collected using an online Typeform -questionnaire. The questionnaire reached respondents from many different Finnish localities, mainly from cities. The final data consisted of 1320 individuals and it was analysed using IMB SPSS Statistics 24 software. The following methods were used to analyse data: frequency analysis, an Independent Samples t Test, a One-way ANOVA, and a Post-hoc LSD test. Gender, study year and living area were used as grouping variables to examine the differences between groups. The results show that the students named school as the main source of food literacy. Moreover, the results indicate that awareness regarding food production, dietary health and proteins increase significantly from the first to the third study year. The students acknowledged food production causing environmental problems and that the share of food in the consumer’s climatic impact is considerable. Nevertheless, the students underestimated the climatic impact of cheese and they were unaware of the more specific characteristics of food’s environmental impacts. They also had food-related environmental misconceptions considering packaging, transportation and meat consumption. Moreover, approximately half or more of the students were aware of the connection between excessive meat consumption and the increased risk of distinct common diseases. Most of the students acknowledged a versatile vegetarian diet as being a healthy choice. The study also reveals that female students had notably higher dietary health knowledge than male students. This Master’s thesis study mainly supports the findings of previous studies on food-related knowledge. The results elucidate the extent, characteristics, gaps and misconceptions of students’ food literacy. These findings may be utilized to improve school education on food literacy, alter misconceptions and fill the gaps of knowledge in pursuit of improving the health of people and the condition of the environment.
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(2022)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.
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(2021)The general structure of the vertebrate brain is highly conserved. However, a large amount of variation exists in brain size and shape, both regarding the whole brain and its subdivisions. This variation is caused by selection acting on species’ behavioural traits and shaping the evolution of the brain in the same process. It is known that one of the factors affecting vertebrate brain morphology is ecology, including habitat complexity, activity patterns and diet. The effects of diet on brain size have been studied in primates, bats and small mammals, where frugivory in primates and bats and insectivory in small mammals, are linked to larger brains. The effect of diet on brain morphology has not been studied in squamate reptiles (lizards and snakes) and the ecological factors behind size and shape variation are largely unknown in squamates compared to other vertebrates. Squamates show large diversity in diet preference as well as feeding behaviour in general, which makes them a suitable model organism to study brain evolution. Further, squamates have highly developed nasal chemical senses that are important for feeding behaviour. These factors in mind, it would be expected that diet has an effect on squamate brain morphology, and especially the brain regions important for feeding behaviour, such as the olfactory bulbs in the forebrain. To study the effects of diet on squamate brain size and shape, the brains of 51 squamate species were micro-CT scanned and 3D-brain surfaces were generated for each species. The species were categorized into four diet groups: carnivorous, herbivorous, omnivorous and insectivorous. To analyse shape and size change across species and diet groups, 73 landmarks were placed on each 3D-brain surface, covering all brain regions: olfactory bulbs, cerebral hemispheres, telencephalon, diencephalon, midbrain, cerebellum and hindbrain. The results from this study show that diet affects significantly the shape of the whole squamate brain, as well as the size of the telencephalon. Telencephalon size differed significantly between the herbivorous and carnivorous groups. Diet had no significant effect on the other brain subdivisions studied here, including the olfactory bulbs. Diet is a large part of a species’ ecology and it is very complex behaviour involving several senses and brain regions, which could explain the results obtained from this study. The results from this study are preliminary, but they indicate that diet could be one of the factors affecting brain morphology in squamates. In the future, including other factors of feeding behaviour than food choice and analysing the effects of diet on a deeper level, such as including brain regions within the brain and analysing cellular organization, could shed some new light on how diet affects squamate brain morphology.
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(2021)Tiivistelmä Referat – Abstract One of the major fundamental ecological questions is the composition of a species diet. The diet of a species is crucially linked to finding out its environmental requirements, and information about the possible changes in the diet is needed when studying the impact of environmental changes such as climate change on species. Siberian flying squirrel (Pteromys volans), classified as endangered in Finland, is a species living in coniferous and mixed forests. More precise information about the dietary habits of the species is needed to support conservation. The aim of my thesis was to investigate the diet composition and diet diversity of adult flying squirrels using DNA barcoding of their excrement pellets, a technique that provides highly accurate information quickly and effectively. The main research questions were whether the diet varies between sexes and seasons, whether diet has an influence on body condition and breeding success of the females, and whether diet diversity is related to the amount of suitable forest habitat near the nests. We collected faecal samples from 51 different flying squirrel individuals from two different study areas near the cities of Vaasa and Pietarsaari in June of 2020. Another set of samples from 8 individuals was collected in November 2020 in Vaasa. The collected samples were sent to a laboratory in Turku, where the DNA barcoding was conducted. I then made further statistical analyses from the laboratory results using general linear models to test my study questions. Although the sample size was too small to obtain statistically significant results for all the research questions, my results indicated that the diet of the Siberian flying squirrel differs between males and females just like its other living habits. Male flying squirrels have more diverse diet than female flying squirrels which have more specific and narrow diet, as they also have smaller home ranges during the breeding season and are more linked to their nesting forest patch compared to males. The aspect that female flying squirrels are more specialists during breeding time is crucial for the species conservation planning. DNA barcoding studies with bigger sample sizes should be done to further investigate the relationship between diet diversity and individual’s body condition and to ascertain the statistical significance to the results of this study.
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