Masteruppsatser, Biologi / Institutionen för biologi och miljövetenskap

Permanent URI for this collectionhttps://gupea-staging.ub.gu.se/handle/2077/69815

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Testing the resilience of Apis mellifera mellifera with other subspecies in Sweden: Nectar sources and mismatches in pollination timing during adverse weather
(2025-08-20) Faraaz, Aamir; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskap
The European dark honey bee (apis mellifera mellifera) is one of several honey producing Apis species and is considered to be the most economically important globally, for pollination services as well as for honey production .It plays a vital role in maintaining biodiversity by providing essential pollination services to numerous wild plants and crops. Its role as a pollinator supports the reproduction of both cultivated and wild plants, which, in turn, contributes to the stability and resilience of ecosystems. This research aims to investigate the resilience of apis mellifera mellifera with other subspecies such as Buckfast,carnica and ligustica and also what kind of nectar sources are used by these subspecies and how adverse weather affects bees foraging in honey yield. Samples were collected from various parts of Northern and central regions of Sweden such as Södertälje, Arboga, Västerås, Östervåla. Pollens were then observed from 18 different slides to see the abundance of different flora, around 33 different types of pollen were found. mellifera showed a little more resilience as compared to other subspecies; its foraging diversity was also higher as compared to other subspecies. The reason could be that mellifera is adapted to this climate as compared to Buckfast which is a hybrid species and carnica which originates from balkan region. This study helps us to identify the different subspecies behaviour in cold climates which in turn can help us to strategize for crop pollination stability, biodiversity support and bee conservation efforts particularly in Sweden.
Evaluating the status and potential of honey production in Nepal. Insight from pollen analysis and beekeeping practices
(2025-08-20) Gyawali, Aarati; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskap
Honey production is essential for sustaining rural livelihoods and preserving ecological balance in Nepal. Although it is significant, studies focusing on the authenticity and plant composition of Nepalese honey are still scarce. This research investigates the existing conditions and future possibilities of honey production nationwide, concentrating on pollen analysis to gain insights into bee foraging behaviours and the quality of honey from various ecological regions. Nepal's landscape features a broad elevation spectrum from the subtropical Terai lowlands to the temperate hilly areas, providing diverse ecosystems. Samples of honey were gathered from various sites in Nepal and transported to Sweden for laboratory testing. Pollen grains were obtained from each sample, mounted on microscope slides, and classified to assess the variety and prevalence of floral sources, in addition to checking for potential adulteration. Statistical and floristic evaluations were performed to investigate the connection between geographic origin and pollen diversity. More than 70 distinct types of pollen were recognized, featuring some uncommon and previously unrecorded species. The Brassicaceae family was identified as the predominant nectar source, highlighting its significance in both wild and cultivated honey production systems. Honey sourced from hilly areas exhibited greater pollen diversity and was deemed more genuine, whereas samples from the Terai indicated the possibility of sugar feeding in beekeeping, raising concerns about honey purity in that region. This study shows the value of melissopalynology in determining the plant and geographic sources of honey. The results provide important perspectives on both traditional and contemporary beekeeping practices in Nepal and emphasize the necessity for better quality control, conservation initiatives, and region-specific beekeeping strategies
Assessing patterns of extinction risk among mammal species in Nigeria: a comparative analysis of human impact
(2025-08-15) Asanbe, Bernard; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskap
This study aimed to evaluate how biological traits influence extinction risk among mammal species in Nigeria, and how these traits interact with specific anthropogenic threats such as agriculture, urbanization and climate change. Focusing on mammal species in Nigeria, we used phylogenetic logistic regression to test the influence of five biological traits: body mass, brain mass, generation time, current geographic range and historical range contraction, on extinction risk across 9 IUCN threat categories. Standardized models were used to compare trait sensitivity across threats. Brain mass emerged as the most consistent and influential predictor of extinction risk, particularly under threats such as agriculture, biological resource use and urban development. Species with larger brains, often primates and carnivores, were highly vulnerable. Geographic range size was a strong negative predictor of risk across most models, with range-restricted species more susceptible to habitat loss and fragmentation. Generation time was positively associated with risk under direct human pressures but inversely linked under climate threats. Body mass showed weak and inconsistent effects, which suggests its influence may be secondary to cognitive or spatial traits. The number of species affected was highest under human threats, compared to climate change or pollution. Extinction risk in Nigerian mammals is shaped by intrinsic traits that interact predictably with human pressures. Species with large brains, small ranges and slow reproduction are at greatest risk. Trait-based models can improve conservation planning by identifying vulnerable species before population declines become critical, especially in regions facing intensive land-use change.
Environmental and social determinants of elephant walking speed in conflict-prone areas
(2025-07-01) Kleinjan, Lynn; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskap
African savannah elephants (Loxodonta africana) are keystone species whose movements play a crucial role in shaping ecosystems. Yet, their populations are under increasing pressure from poaching, habitat loss, and rising levels of human-elephant conflict (HEC). Gaining a better understanding of how elephants move, particularly their walking speed, can help improve conservation efforts and reduce conflict. This study explores how time of day, environmental conditions (temperature, rainfall, water availability), and social factors (sex and age class) influence walking speed in elephants living in the Makgadikgadi Pans National Park in Botswana, a high-conflict area known for its large number of male elephants, called bulls. Between June 2014 and April 2017, camera traps were placed along established elephant paths to monitor movement. The data were analysed using linear models and generalized additive models (GAMs). The direction of travel turned out to be the strongest predictor of speed: elephants moved significantly faster when heading toward water or food. Time of day also had a clear influence, with a 24-hour rhythm showing higher speeds at night, likely reflecting both thermoregulatory needs and possible crop-raiding behaviour. Temperature had a non-linear relationship with speed: elephants moved faster as temperatures rose, up to a point, after which their speed dropped, suggesting an optimal temperature range for activity. Interactions between time of day and temperature, as well as between time and direction, pointed to a complex mix of behavioural drivers. Other factors like rainfall, sex, and age had only weak or inconsistent effects. Taken together, these findings, based on a unique ecological and social context, shed light on the movement patterns of elephants and point to the importance of considering time, environment, and social structure when developing conservation strategies and managing coexistence in human-altered landscapes.
Arctic plant phenology and abundance. Understanding temperature-sensitivity and warming impacts
(2025-07-01) Landgren, Malin; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskap
The Arctic is warming four times faster than the global average, driving major changes in tundra ecosystems. One key response is shifts in plant phenology, the timing of life events like flowering. These shifts can cause trophic mismatches, affecting insects, birds, mammals, and human societies. Plants that adjust their phenology with warming are considered temperature sensitive. Understanding plant phenology is key to predicting how tundra vegetation may change in the future. With this in mind, our study aims to understand the relationship between temperature sensitivity of plant phenology and abundance change, both experimentally and over time with natural warming. We used an experimental setup in Greenland, Disko Island, with warming chambers (open top chambers, OTC), creating a 1.5–3°C warmer and more humid environment, and monitored plant phenology in both OTCs and control plots. Previously recorded abundance data from the same site was used to see how experimental warming affected abundance, along with a 30-years old dataset to explore changes over time with natural climate warming. Our results showed that flowering time advanced with warming, indicating that most species were temperature sensitive. Betula nana and Bistorta vivipara were most sensitive, flowering 7 and 15 days earlier, respectively, under experimental warming. We found no strong overall trend of increased abundance under experimental warming; over time the trend was more positive but still modest. B. nana consistently increased under both experimental and natural warming, while B. vivipara showed a continuous decline. Overall, we found that temperature sensitivity alone did not predict abundance changes. This suggests that other environmental factors (e.g. microclimate variation, soil conditions, and species interactions) likely play important roles. Our study also highlights species-specific responses, with shrubs like B. nana would likely expand, while species like B. vivipara may struggle in a warmer Arctic.
Exploring the diet of harbour seals (Phoca vitulina)
(2025-06-30) Schött, Malin; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskap
Changes in fish species abundance in the marine environment, can influence the prey composition of harbour seal diet and ultimately cause a decline in somatic growth and pregnancy rates. Thus, diet analysis enables early detection of changes in the marine ecosystem with consequences for seal health. The present study aims to assess both the overall diet of harbour seals and to elaborate several statistical methods to describe what we can learn from different methods of analysis. In particular, the variation in consumption is compared when the samples are treated individually (per sample) or at the population level (pooled samples). Diet composition was determined by identifying remains of the prey species in scat samples. To assess the variance in diet composition of individual samples, the data was tested for Local Contribution to Beta Diversity. To further explore differences among scats, two different distances were applied, the Jaccard similarity and the Bray-Curtis dissimilarity. Wrasse, Trisopterus spp., haddock/pollack/saithe, flatfish and cod were shown to be the most important prey species when accounting for abundance and haddock/pollack/saithe, wrasse, cod, Trisopterus spp. and flatfish when accounting for biomass. The results showed moderate to high variation in diet composition among scat samples, and the data treatment (individual samples or pooled) did affect the results significantly regarding prey species abundance estimated to be consumed by seals. However, when the biomass of prey species was estimated, the two methods produced similar results regarding the importance of different fish prey species in the diet. The results imply that former studies treating diet samples pooled can be used for comparisons with recent samples, when it comes to relative importance regarding biomass in the seal diet. The result showed that herring, which historically was highly important in the diet of harbour seals, showed low abundance in the present study. This could be explained by their migratory patterns or the decline in the fish stocks due to overfishing. The variance in prey species composition among scats can indicate that harbour seals show individual habitat- or prey species preferences or random events in encountering prey while foraging.
Potential of behavioral and morphological bias in invasive brook trout capture methods
(2025-06-30) Olson, Mitch; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskap
Invasive species in aquatic systems can result in numerous adverse effects such as reduced native populations, loses in biodiversity, and degraded ecological services. When these effects become too great to ignore management techniques available for invasive fish programs vary greatly. Selective manual methods of species removal such as electrofishing and trapping have been shown to be part of successful removal programs but typically require extensive effort and multiple treatments. Electrofishing requires specialized equipment and training to actively capture invasives whereas trapping uses commonly available traps and after installation is more passive. Due to differences between capture method it was theorized by this study that capture method may be biased for different behavioral and morphological characteristics of invasive brook trout (Salvelinus fontinalis) in Swedish streams. It was theorized that bolder brook trout would be selected for by trapping as the method requires trout to investigate and enter the new and foreign traps while electrofishing would select for less bold individuals that would remain stationary upon disturbance. Morphological differences could occur as salmonids such as brook trout demonstrate high phenotypical plasticity as potentially part of dietary niche exploitation which has been linked to personality. Behavioral analysis consisted of startle response field boldness testing at the study location, group feeding boldness, and individual feeding behavior in a simulated stream. Morphological analysis was performed using facial digitization and principal component analysis. Results showed that capture method did not select for size, weight or individual feeding or in-group boldness. Morphological analysis showed that while two facial morphs made up 47% of facial morphological differences there was no significant difference in facial morphology. Trapping did select for more bold than shy trout. This study’s findings suggest that using only trapping will select for more bold trout, but further studies are needed to understand the population impacts.
The impact of fasting and refeeding on intestinal fluid transport capacity and cortisol levels in salmonids
(2025-06-30) Gagandeep, Kaur; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskap
The intestine in fish, as in most animals, plays a central role in nutrient absorption and contributes significantly to osmoregulatory balance, particularly under fasting or salinity-related stress conditions. This thesis investigated the impact of fasting and subsequent refeeding on intestinal fluid transport capacity, empty gut mass, plasma ion concentrations, and cortisol levels in seawater-acclimated rainbow trout (Oncorhynchus mykiss). The primary aim was to determine how fasting influences fluid absorption in the proximal and distal intestine and how systemic responses such as ion balance, intestinal mass, and endocrine regulation are affected. Fish were fed on day 1, followed by fasting periods of 24 to 120 hours, and then refed for 48 hours. Fluid transport was assessed using the non-inverted gut sac method. Plasma concentrations of Na⁺, K⁺, Ca²⁺, and Cl⁻ were measured using a plasma ion analyser, and cortisol levels were quantified using radioimmunoassay (RIA). Fluid transport per intestine (μL/h) increased with fasting and remained elevated after refeeding, particularly in the distal intestine. However, when normalized to surface area (μL/h/cm²), no significant differences between fed and fasted were observed, suggesting that tissue-level transport efficiency remained stable. Empty gut mass increased during fasting, especially in the distal region, and in the refeeding group it remained reduced in both intestinal regions. Plasma sodium levels decreased significantly during early fasting (24-48h) but recovered by 72h, while potassium showed a transient increase at 48h. Calcium was highly variable, and chloride remained unaffected. Cortisol levels progressively increased with fasting duration, peaking at 120h, and declined after refeeding. Notably, the fed control group showed poor feed intake, which may have limited the reliability of comparisons against truly fed individuals. These findings may suggest that intestinal fluid transport remains functionally responsive during extended fasting, potentially supported by plasma cortisol levels. However, the absence of histological and molecular data limits clear interpretation. Future studies should incorporate freshwater comparisons to further elucidate fluid transport rates under fasting conditions in rainbow trout.
Genetic regulation of the short-term stomatal CO2 response in Arabidopsis thaliana
(2025-06-30) Joseph, Neethu; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskap
Plants respond to various environmental stimuli, including elevated CO₂, by partially closing their stomatal pores. This partial closure reduces water loss through transpiration while allow-ing photosynthesis to continue. Understanding how plants regulate this response is important for improving water use efficiency, especially in the context of climate change. However, the signalling pathways that control stomatal closure in response to CO₂ are complex, and many components are still unknown. This study aimed to investigate the genetic basis of CO₂-induced stomatal closure in Arabidop-sis thaliana using a Multiparent Advanced Generation Inter-Cross (MAGIC) population based on 19 founder lines. Gas exchange measurements were taken in 206 RILs, and quantitative trait locus (QTL) mapping was used to identify the genome regions linked to stomatal response to elevated CO₂ and related traits. A significant QTL was found on chromosome 1 associated with the percentage reduction in stomatal conductance in response to elevated CO₂. Further analysis of the genes in this region revealed 15 potential candidates. Additionally, a QTL on the same chromosome was linked to the speed of the response when CO₂ concentrations increased from 420 to 800 ppm. This study provides a foundation for exploring these QTLs and candidate genes, with the po-tential to improve plant adaptation to increased CO₂ and enhance water-use efficiency in future climates.
How environmental variation affects genetics trade-offs among life-history traits
(2025-06-30) van Putten, Deborah; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskap
To predict how populations will adapt and evolve, it is essential to understand how costly life-history traits genetically covary and trade off in response to variable environments. These trade-offs can limit the response to selection and thus can constrain adaptation in populations. Understanding these genetic trade-offs is especially important for managing pesticide resistance in pest populations. My thesis aims to quantify genetic effects between life-history traits and varying environmental conditions, in Helicoverpa armigera moth larvae infected by different doses of a fungal biopesticide. Survival, pupal mass and development rate were measured as response variables. To estimate genetic effects, a half-sibling design was used to partition sire variance from the phenotypic variation. Although the biopesticide did not appear to affect traits on a phenotypic level, including low mortality across all doses, the Bayesian model revealed some evidence for genetic effects. Genetic correlations within development rate were highest for similar doses and lowest for vastly different doses, suggesting gene-by-environment interactions. A positive genetic correlation between pupal mass and development rate was found in the highest dose, while the genetic correlations in the lower doses were closer to 0. This may suggest that certain genetic effects only influence performance under high stress conditions, and that genetic correlations can be masked at low stress environments, due to favorable conditions. Despite limited statistical power due to the number of half-sibling families, my results show that genetic effects are environment-dependent. My thesis shows the importance of considering environmental variability when predicting evolutionary responses, especially in the context of managing pesticide resistance, where hidden genetic constraints may only emerge under stress.
The Population Crisis in Sub-Saharan Africa: Biodiversity Threats and Swedish Foreign Aid Perceptions
(2025-05-21) Köster, Ella; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskap
The global population crisis remains underrepresented in public discourse, despite its critical impact on biodiversity and sustainable development. Population growth intensifies environmental challenges such as habitat loss, exploitation of resources, and greenhouse gas emissions. This thesis examines 1) the relationship between human population density and the threat to wild species in countries in Sub-Saharan Africa, nearly all of which face high population growth, and 2) public support to family planning in international aid to Africa in a donor country, Sweden. Correlation analyses with data from the IUCN Red List and population metrics from the World Bank show a positive association between human population density and species threats across the following taxonomic groups: all assessed vulnerable, endangered, and critically endangered species, Animalia, Plantae, Primates and birds combined, and primates and birds separately. Equatorial Guinea and the Gambia, deviate from the trend in the graph including all assessed species (vulnerable, endangered, and critically endangered), making them the focal point of discussion. In Equatorial Guinea, primates and plants are particularly threatened, while the Gambia mainly experiences threats to birds, both based on the measure species threat density. In a survey among 1,333 Swedes, they ranked foreign aid alternatives to Africa. 42% chose democracy and human rights as the highest priority, 41% chose humanitarian aid, 12% chose family planning, while only 5.5% chose trade and business. There were no significant differences in rankings across gender, age, or geographic region; however, respondents with lower education levels were more likely to prioritize family planning compared to those with higher education. Despite little information in Swedish media and books about family planning, Swedes recognized its importance in reducing population growth in Africa. Human population dynamics need to be part of public discourse and policies.
Genetic diversity of the green macroalga Ulva linza in Kattegat and the Baltic sea with recommendations for aquaculture
(2025-02-24) Janning, Mona; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskap
Genetic diversity is essential for the establishment of a sustainable seaweed aquaculture, as it serves as the foundation for population health and resilience to environmental stressors. The interest in green algal species cultivation has grown worldwide, particularly of the genus Ulva, commonly known as sea lettuces. Ulva is characterized by a haplodiplontic life cycle, with partially clonal reproduction. The mode of reproduction, sexual versus asexual, affects the genetic composition of a population and thereby shaping its ecological success and adaptive capacity. In this MSc thesis, the genetic diversity of U. linza was assessed and clonal lineages were characterized along the salinity gradient of Skagerrak, Kattegat, Öresund, and the Baltic Sea. To assess the genetic variation, 67 samples of U. linza were genotyped with 21,205 2b-RAD derived single nucleotide polymorphisms (SNPs). Overall, clonality was high. Among the 67 samples, 31 multilocus genotypes (MLG) were identified, two of which comprised 10 ramets each. Individuals in the Baltic Sea are predominantly clonal and genetic diversity in this region is low. In contrast, the highest genetic diversity was identified in Kattegat and Öresund with several smaller clonal lineages. In the Baltic Sea, individuals belonging to the same clonal lineage showed a broad distribution. This is the first study outlining the genetic diversity of U. linza in the Nordics. The here identified clusters of clonality and genetic variation can be used for prioritizing genetic resources of populations for the recruitment of individuals for aquaculture practices.
Sex-specific behavior in juvenile brown trout (Salmo trutta). Investigating the impact of sex on dominance and aggression among juvenile brown trout by using new DNA-based sex identification.
(2025-02-17) Olsen, Evelina; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskap
In salmonid populations, social structures generate dominant individuals that typically display higher ag-gression, securing high-quality resources and optimize chances of survival. Studies within the subject of dominance and sex-specific behavior within adult salmonid groups concludes that salmonid males usually take on the dominant role, likely due to distinct reproductive roles between the sexes. Similar previous research on juvenile salmonids is limited and instead indicates that males are also more aggressive, but not consistently more dominant. This study addresses this gap in knowledge by combining a short-term domi-nance assessment using an artificial stream and 96 brown trout captured by electric fishing around Lunz am see, Austria, with a non-lethal DNA sex identification method using DNA from the same individuals. The study explores how residency during 10-day rounds and time of day influences the overall aggression level and when dominance is established. Additionally, it investigates how sex and group body size influences dominance and aggression. The result indicates that both residency and time of day were significantly af-fecting the overall aggression, with higher levels at dawn, consistent with earlier studies. The interaction of day and time also significantly affected the establishment of dominance, with early dominance also visible at dawn, and were overall stable from day 8. Both sexes became dominant within the groups, but the ag-gression in groups with female dominant individuals significantly increased with group body size, opposite to earlier studies. These findings may provide insight into how various factors can influence aggression and dominance in juvenile brown trout populations, which could help develop strategies for their conservation.
Allometric models for aboveground biomass in small and multi-stemed trees in Rwanda
(2025-02-17) Svensson, Carl; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskap
Estimates of aboveground biomass (AGB) of trees are crucial for understanding how forest ecosystems influence the global carbon cycle and tropical forests are of particular importance. Allometric equations are used to estimate AGB but the allometric relationship differs between sites, species and size of the trees. Most developed equations focus on large trees with one dominate stem. This study focuses on estimating AGB in a population of small and multi-stemmed trees from species native to Rwanda. It aims to test the validity of available equations developed for larger trees and to develop new equations for accurate AGB estimates. Additional measurements of multiple stem diameter, stem count and crown area are tested. A total of 83 trees from 8 species were harvested, and their AGB was measured. The samples’ diameter at breast height ranged from 1.6-13.4 cm and 16 samples had multiple stems. Wood density, height, all diameters at 1.3 m and 0.3 m above ground and crown area were measured. AGB was compared to the estimates derived from several equations reported in the literature. New equations were developed through regression analysis. The results show that a commonly used pantropical equation also is valid for the smaller trees of this study. This equation performed almost as good as the model developed in this study, when using the same variables. Moreover, the equation, as well as the simplest equation of this study, is biased regarding trees with different number of stems. Additional measurements of multiple stem diameter or two measurements of the main stem, at different heights, as well as a stem count largely improves the estimates, in particular for multi-stemmed samples. Crown area also improves the estimates. New site- and species-specific equations are presented in this study.
Dynamics in brood chamber pH of the European flat oyster (Ostrea edulis) in response to ocean acidification
(2025-02-10) van Acker, Lore; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskap
Ocean acidification is posing a threat to marine bivalve species who struggle to deposit calcium carbonate in order to grow their shell. Some oyster species have developed a brooding reproductive strategy which might help them cope with this acidification stress. Brooding oysters have shown to be more resilient against ocean acidification than broadcast spawning oyster species. It is suspected that because the brood chamber is on top of the maternal gills, the mothers add carbon dioxide into the chamber from her respiration. This suggests larvae evolved to develop in a more acidic environment than the surrounding water column. Through exaptation the larvae may have coopted traits needed for development in the brood chamber which now enable them to be more resilient to ocean acidification. In this study, we measured the pH inside the brood chamber of Ostrea edulis under current and future predicted ocean conditions (i.e., elevated temperature and decreased seawater pH) to get a better understanding of the ambient-maternal relationship on brood chamber pH fluctuations under ocean acidification scenarios. The results suggested that maternal respiration indeed makes the brood chamber always a more acidified environment then the surrounding water. Elevated temperatures in the surrounding water slightly lower the pH as a result of increased maternal metabolism. Yet lowering the ambient pH causes a much larger and significant reduction of internal pH levels since the oyster is constantly filtering the overlaying water while the valves open. Additionally, there seems to be a positive relationship between shell gape and internal pH changes suggesting that the mothers behaviour may also influence how fast and to which level pH values can drop inside the brood chamber. These results give an indication of what conditions brooding oysters larvae will have to face in the future and helps determine possible winners and beneficial strategies in an acidified ocean.
NOVEL CULTIVATION METHOD INCREASES CRUDE PROTEIN CONTENT AND IMPACTS SENSORY ATTRIBUTES OF RED SEAWEED PALMARIA PALMATA
(2025-01-14) Skagerlind, Moa; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskap
The red seaweed Palmaria palmata could be a sustainable protein source with a low environmental footprint to feed a growing global population. However, its protein content should ideally be optimised to be on par with other protein sources and its sensory attributes as a food ingredient must appeal to consumers. This study aims to enhance the crude protein content of P. palmata by using herring production process water (HPPW) in the cultivation as nutrient enrichment. Moreover, the study establishes a sensory profile of cultivated P. palmata and investigates if HPPW changes its sensory attributes. It does so through two cultivation experiments and one sensory evaluation of the cultivated biomass. In the first experiment, a suitable dilution level of HPPW was established. This knowledge was used when scaling up in the second experiment where growth, crude protein content and chlorophyll a were compared between cultivation in HPPW and seawater controls. Biomass from the second experiment was then tested by a selected and trained panel in a sensory evaluation, using quantitative descriptive analysis (QDA). The results show that cultivation in HPPW significantly increased the crude protein content, chlorophyll a and growth of P. palmata. Additionally, the findings suggests that constant supply of nutrients, e.g. by having flow-through of water, is of great importance when growing P. palmata in land-based tanks. The sensory panel established that cultivated P. palmata has a strong taste of umami, salt and fish, a prominent ocean scent and a firm, sticky and chewy texture. These attributes were shared between the two evaluated treatments. However, the HPPW changed the appearance of P. palmata as colour, structure and glossiness significantly differed from seawater control. This study showcases that HPPW can have a positive impact on the nutritional characteristics and change the sensory attributes of P. palmata, establishing this red seaweed’s role as an important sustainable protein source that contributes to circular food production.
Is the city buzzing? Functional diversity of wild bees in an urban park.
(2024-11-29) Axelsson, Lova; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskap
Wild bees are in decline, threatening the ecosystem functioning and pollination services that we are so dependent on. The rapid fragmentation and urbanisation are some of the major threats to the bee habitats, with deteriorating dietary resources and suitable nesting sites as some of the consequences. Quantifying functional traits is one important way of measuring biodiversity, instead of solely focusing on species richness. Therefore, the functional traits of the wild bee fauna found in the park Slottsskogen, Gothenburg, Sweden, were investigated and compared to two different rural areas with high nature values in two munici-palities on the Westcoast of Sweden: Borås and Mark. The functional traits were compiled through literature search, and tongue lengths, foraging distances and body sizes were estimated based on measured intertegular distances. The three different assemblages were then compared through a principal coordinate analysis. The traits making up most of the variation between the assemblages were whether or not the bees had pollen-carrying structures, their preferred pollen and nectar sources, what kind of habitat they choose to inhabit and if they nest aggregated or not. Nearly all bee species in Slottsskogen are polylectic, but the proportions of oligolectic bees were not significantly higher in Borås and Mark municipalities. The functional evenness and divergence within all three assemblages were high, but the functional richness of Slottsskogen was lower than both Borås and Mark municipalities. Comparing the beta diversity, the dissimilarity of the functional traits between Borås and Mark was low, and higher when Slottsskogen was compared to either of the two more rural assemblages. Slottsskogen is shown to be a sub-sample of the other two localities, indicated by a high nestedness coefficient, which suggests that the diversity differences are mainly due to dissimilarities in area size and nature types, and sampling methodologies. This is not to say that Slottsskogen is remarkably species-poor, given its circumstances. Nonetheless, to increase the functional diversity and richness of wild bees in a park like Slottsskogen, different measures are likely needed to enrich the dietary and nesting resources available, and the habitat diversity of the park.
Movement patterns and social dynamics of male African Savannah elephants (Loxodonta africana). Following the steps of giants.
(2024-11-29) Isaksson, Simon; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskap
Wildlife populations are decreasing all over the globe. Conflicts with humans increase as the wild landscapes shrink. The African savannah elephant (Loxodonta africana) used to roam in most parts of Africa but only a fraction of the historical numbers remains today. Botswana is home to 130,000 elephants, about 1/3 of the elephants remaining in Africa. Savannah elephants have traditionally made large seasonal migrations for resources, but landscape fragmentation has made these movements much harder. The savannah elephant is an endangered species and even if the social lives of matriarchal families are well-studied, the groups that the bulls may form have been less so. This study aimed to fill some of these gaps and contribute with knowledge about movement patterns and social dynamics of males to better conserve the species and decrease human-wildlife conflicts. Photo identification was used to track individuals in the Makgadikgadi and Nxai Pan National Park in Botswana to estimate how many days the bulls stayed inside and outside the park, and how it differed between different age groups and seasons of the year. I also investigated the social dynamics of male associations to increase the knowledge about bull groups. I found that a bull on average stayed for 37 (CI 31-48) days inside the park before leaving the park for 108 (CI 87-138) days. My findings also suggest that the youngest males stayed and left for shorter periods under both the wet and dry seasons compared to the oldest bulls. Both age groups stayed and left for longer periods during the dry season compared to the wet. The research also showed that bull association isn’t random even though most relationships will be short-term. My results indicated that elephant movement generally increased during the wet season and that young bulls in general moved more in and out of the park, increasing their risk of conflict with people living in the surroundings. It also indicated that elephants do have preferred companions, and all these findings should be taken into consideration for the conservation of the species.
EVALUATION OF THE PERFORMANCE OF MARINE ANAMMOX, Candidatus SCALINDUA, UNDER REAL RECIRCULATING AQUACULTURE SYSTEM NITROGEN CONDITIONS
(2024-11-28) Marqué, Amélie; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskap
In an effort to find a sustainable and nutritious food source to meet the demands of an increasing population, recirculating aquaculture systems (RAS) have proven to be a promising candidate. RAS are tank-based setups which mechanically and biologically filter water before recirculating it back into the system. A current challenge with RAS is the potential accumulation of nitrogenous wastes, ammonium (NH4 +), nitrite (NO2 −), and nitrate (NO3 −), which could impact the health and welfare of fish. This waste, primarily in the form of NH4 +, is generated as a byproduct of protein synthesis during digestion, and from the microbial decomposition of organic matter such as feces. In RAS, nitrifying bacteria transform NH4 + into NO3 −, via NO2 −. This NO3 − product needs to be removed from the system through frequent water exchange or by denitrification. Recently, an alternative pathway has been explored involving anaerobic ammonium oxidizing (anammox) bacteria for nitrogen removal from marine wastewater. Anammox bypasses nitrification and denitrification, and directly converts NH4 + to harmless nitrogen gas (N2) by using NO2 − as an electron acceptor. The performance of the marine anammox species Candidatus Scalindua in treating enriched synthetic RAS wastewater has previously been established, however the concentrations of NH4 + and NO2 − (ca. 30 mg/L) used in previous experiments are unsuitable for fish. As such, Experiment I of this thesis assesses the performance of the bacteria when exposed to real RAS nitrogen conditions in two phases. In the first phase, the bacteria were fed with a synthetic feed with 1.4 mg/L of NH4 +, 1.7 mg/L of NO2 −, and an additional trace element (TE) mix. Average removal rates of 80% for NH4 + and 85.2% for NO2 − were achieved. During the second phase, NH4 + and NO2 − concentrations remained the same but the TE mix was removed, this phase is still ongoing. Similarly, previous research showed that Ca. Scalindua tolerated NO3 − concentrations up to 1600 mg/L, but at 3200 mg/L the total nitrogen removal rate collapsed. Therefore, Experiment II of this thesis aims to identify the exact NO3 − tolerance threshold of Ca. Scalindua by incrementally increasing the concentration of NO3 − starting at 1600 mg/L and going up by 200-400 mg/L every 20-40 days. This experiment remains ongoing but preliminary results showed that the bacteria were able to tolerate concentrations up to 2800 mg/L and had an average removal efficiency of 92.1% between 2000 mg/L and 2600 mg/L. With these two experiments, it can be concluded that Ca. Scalindua can successfully be used to treat marine wastewater under real RAS conditions and adapt to incrementally increasing NO3 −concentrations.
REPLACEMENT OF FEED FOR AFRICAN CATFISH (CLARIAS GARIEPINUS) WITH BYPRODUCTS FROM LOCAL FISHING: Are local fish wastes trash or treat, can they replace commercial feeds for more sustainable production?
(2024-11-28) Claus, Joris; University of Gothenburg / Department of Biological and Environmental Sciences; Göteborgs universitet / Institutionen för biologi och miljövetenskap
A persisting issue with current aquaculture practices is the large-scale demand for fishmeal in aquafeeds, which puts pressure on wild fish stocks as well as on markets, creating environmental and social dilemmas. Omnivorous warmwater species like African catfish hold the potential for local and sustainable fish production in recirculating aquaculture systems (RAS). But the feeds used in production facilities are largely fishmeal based, contributing to the global demand problematic. The use of locally available fish products has potential to be an alternative to traditional fishmeal. Two byproducts from the fishery industry in South Sweden are tested in this study. The first is trimmings like heads and carcasses from herring fisheries (H). The second is freshwater cyprinid fish, which are caught from lakes to reduce eutrophication (“reduktionsfiske“, R). I conducted a feeding trial in an experimental RAS, approximating commercial production conditions. For the three experimental groups C (control, standard catfish pellets), H, and R, I evenly distributed 90 African catfish into 12 tanks to create triplicates per group. After 30 days, the average weight increase per group was 55.6% in the control, 67.6% in the R, and significantly lower 25.6% in the H. The mean feed conversion ratio (FCR) per treatment group was 0.80 in C, 0,96 in H, and 0.63 in R. No difference in health and welfare was found between the treatment groups and the control group according to haematology and liver weight assessment. Altogether, the R feed showed very promising results because it showed good results in health and welfare, growth, FCR and final product taste. This locally and cheaply available feed or potential feed ingredient could be a starting point for more profitable production of sustainable African catfish feed in Sweden.

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