The gulf of Nicoya is one of the most productive estuaries in the world and is home to many artisanal fishermen who rely on the gulf as both an economical source but also a way of feeding their families. The Marine Protected Area (MPA) named “Marine area for responsible fishing Paquera – Tambor” is located between Paquera and Tambor on the Nicoya peninsula on the Pacific coast of Costa Rica. In this area, fishing is regulated by laws that are enforced by Instituto Costarricense de Pesca y Acuicultura (INCOPESCA), a Costa Rican governmental organ. This study investigated gillnet fishing in the Marine area for responsible fishing Paquera – Tambor by comparing previously collected data from 2016, 2017 with data that was collected in 2023 and investigated the artisanal fishermen perception about the fishing and regulations through interviews. The parameters compared between the years were, (I) the bycatch species, (II) the target catch per net, (III), the total amount of fish caught per net, and (IV) the mean length of the fish. The 2023 data was collected by laying down gillnets in the same area and with the same equipment and effort as done in 2016 and 2017. The target catch was significantly lower in 2023 compared to that of 2016 and 2017. There was a similar negative trend, albeit nonsignificant for the total amount of fish caught per net. The interviews were carried out with a standardized survey and, 10 fishermen active in this protected area were interviewed. This was done to get a wider view about the fishing in the gulf of Nicoya and to compliment the results of this study. All the interviewees expressed negative views about INCOPESCA and three claimed that INCOPESCA officials can be open to bribery. All interviewees contested that the fishing had become noticeable worse during their time as artisanal fishermen. Eight reported that they thought that solely relying on fishing as a means of stable income will not be sufficient in the future. The investigations conducted in this study suggest that INCOPESCA have not succeeded in managing a sustainable fishery in this marine area of responsible fishing. More research is required to gain a better understanding of how the gillnet fishing in the gulf of Nicoya affects the ecosystem and its fish stocks.

Temporal stratification in lakes due to high air temperatures and dynamic wind conditions changes the environment for organisms in the depth gradient. For fish that have narrow requirements for temperature and oxygen conditions, stratification can lead to a significant reduction in habitat volume during the summer when surface temperatures are high. In Sweden, temporal stratification occurs between July and October. The vendace (Coregonus albula) is a cold-water fish that is found in several waters around Sweden. In Lake Mälaren, there is targeted commercial fishing for the species, but the total annual catch has drastically decreased in recent decades. Shrinking habitats and longer periods of temporal stratification during the summer could be a partial explanation. Understanding and predicting changes of the vendace populationin Lake Mälaren requires mapping of available habitat during the summer temporal stratification. This study has investigated the worst habitat conditions in terms of habitat thickness for vendace during the years 2017-2022 in Lake Mälaren based on the habitat requirements temperature ≤18 °C and DO concentration ≥2 mg/L. The spatial distribution in two basins where analysed. The results showed that the vendace had limited available habitat in three of seven water bodies investigated (habitat thickness ≤2.5 m). The spatial analysis of the two basins showed that habitat volume represented 41 % and 11 % of the total volume of water in each basin. The available habitat of the vendace during the summer temporal stratification in Lake Mälaren is thus limited in parts of the lake.

No description available.

No description available.

Biodiversity loss as a consequence of extreme weather is becoming more frequent. To ensure the stability of future ecosystems it is important to study what makes species survive extreme weather events. Here I analyzed habitat choice  during and after a drought of the specialized butterfly Phengairs arion to determine where the species managed to survive an extreme drought on Gotland (Sweden). Four years (2018-2021) of mark-release-recapture data was used to estimate change in population size and (large scale) distribution based on a hectare grid survey. A small scale habitat preference study was made to add to the larger scale. The small scale is done based on 10x10 m squares. In addition a smaller ant-lure study was done to see how butterfly presence affected ant abundance. This study shows a great decline of the population after the drought in 2018. After the drought the population of P. arion was found in areas with higher tree and bush cover and higher ground moisture index (GMI). The small scale habitat study show that individuals prefer an open landscape with high nectar quantity and sheltering bushes in north east direction. These results show the importance of landscape heterogeneity to buffer for extreme changes in species habitat and that butterfly presence may have a negative effect on population size of Myrmica spp. ants.

The population of common eider (Somateria mollissima) has suffered a dramatic decline in several breeding locations since the 1990s. Predation is described as one of the main reasons, along with other suggested explanations such as food shortage, environmental pollutants, and thiamine shortage. Data about the common eider in Swedish waters is missing to a large extent. To better understand breeding behavior and predation, my study has investigated basic breeding parameters through camera surveillance at Stora Karlsö from late April until mid-June 2022. My study also aimed to investigate whether camera surveillance is a possible method. In total, 14 females were investigated. The hatching success was determined to be 79 %. Predation was carried out by hooded crows (Corvus cornix) and herring gulls (Larus argentatus). Out of > 400 observed nest days and 14 observed females, predation was only observed nine times. This study concluded that predation may not be a big threat to the species during incubation at Stora Karlsö. The first egg was observed on average on May 4th. The incubation started on average May 8th and lasted an average of 25 days, 12 hours, and 6 minutes. During the incubation period, the females left the nest on average 0.87 times per 24 hours, with a median leaving time of 22:10. These incubation intermissions had an average duration of 31 minutes and did not change over time. The average duration did significantly vary between females.  Further studies are needed to clarify if the females are foraging during the incubation intermissions. Males were observed in the nest area, with most observations between May 3rd and May 8th. This study concluded that camera surveillance is a possible method to investigate the basic breeding behavior of the common eider. The recording should start in mid-April and end in mid-June and an improved camera system is necessary to gain more reliable data.

This study investigates what the future might hold for an endemic goose species, found exclusively in the low Arctic region of West Greenland. Facing a decline since four decades, the Greenland White-fronted Goose constitutes one of few goose populations showing a declining trend. Warmer temperatures on the breeding grounds and improved winter survival seem to benefit most populations of geese. Here, a species distribution model is applied to predict how the environmental conditions of low Arctic Greenland might change in the future. A ‘business as usual’ scenario, projected with two different climate models, indeed showed improved future conditions within the summer range of the Greenland White-fronted Goose. Snow cover, followed by temperature, was found to be the most important environmental factor shaping the distribution. Furthermore, novel potential breeding grounds were located on the southeast coast of Greenland, opposite the current summer range. This area is discussed in terms of becoming a future refuge for this vulnerable population, away from the newly established Greater Canada Goose in West Greenland. Interactions between the two species seem to have increasingly negative effects on the breeding success of Greenland White-fronted Goose. Whether the novel breeding grounds will eventually become colonized or not remains highly uncertain. However, other goose populations have shown such range shifts to be possible. / I föreliggande studie undersöks huruvida förutsättningarna för en endemisk fågelpopulation, hemmahörande i Lågarktis, kan komma att förändras i framtiden. Den grönländska bläsgåsen minskar kontinuerligt sedan fyra årtionden tillbaka, och den tillhör således en av få gåspopulationer som har en vikande populationstrend. Varmare temperaturer i häckningsområdena, tillsammans med ökad överlevnad vintertid, tycks gynna de flesta populationer av gäss. Här tillämpas en modell för artutbredning för att undersöka hur de miljömässiga förutsättningarna i lågarktiska Grönland kan komma att förändras framöver. I processen användes ett ‘business as usual’-scenario, som presenterades utifrån två olika klimatmodeller. Modellerna påvisade mycket riktigt att, när det kommer till de abiotiska förutsättningarna, även den grönländska bläsgåsen borde gynnas i framtidens Arktis. Av de miljömässiga variablerna som användes i processen tycks snötäckt yta, följt av temperatur, vara den viktigaste faktorn i att forma bläsgåsens utbredningsområde. Vidare fann studien att områden längs den sydöstra kusten av Grönland, motsatt dagens utbredningsområde, kan bli potentiellt gynnsamma för grönländsk bläsgås framöver. Idag tycks bläsgåsens föryngringsmöjligheter begränsas av den på Västgrönland nyetablerade kanadagåsen (ssp. interior), vilket här har lett till diskussioner rörande bläsgåsens möjligheter att finna en, om än tillfällig, fristad undan kanadagåsen i framtidens Sydostgrönland. Huruvida den grönländska bläsgåsen kommer att kolonisera dessa områden i framtiden är högst osäkert. Andra populationer av gäss har samtidigt visat att sådana förändringar i utbredning är möjliga.

Biodiversity is declining worldwide, and the biggest reason for this is habitat destruction. In Sweden one third of all the red listed species belongs in broadleaved deciduous forests. The  most common reason for the endangerment of these species is the destruction of the deciduous forest. Pendulate oak (Quercus robur) hosts the largest number of red listed species in Sweden. The reason is this tree grows to be very old, and with age accumulates many different microhabitats that can harbor a variety of different species. One of these species is the endangered longhorn beetle Plagionotus detritus, which specializes in newly dead, sunlit oak trees. P. detritus has over the last century suffered a great decline in its Swedish distribution, mainly because of the lack of sunlit oaks due to encroachment of spruce, and a lack of succession in oak trees.   The aim of this thesis was to investigate which environmental variables that affect habitat choice in P. detritus in an area in central Sweden. I did this by estimating nine different variables collected from oak trees in and around Stockholm- and Solna municipality and associate these variables with the abundance of exit holes. Exit holes are a good approximation of population abundance. In addition, the age of the exit holes was used to investigate the recent historic spread of the species in the area.   I found that Vitality of the tree, the Openness surrounding each tree, and the amount of Canopy cover had the highest impact on the abundance of P. detritus. These results are consistent with previous research findings. I also found indications of a recent west-wards expansion of P. detritus. My result should be useful information for future conservation of the species in neighboring areas.

No description available.

The Greater Hoopoe-Lark (Alaemon alaudipes) is a sedentary bird distributed from Cape Verde and Northwest Africa to India. Four subspecies are usually recognized (A. a. alaudipes, A. a. doriae, A. a. desertorum, and A. a. boavistae), with molecular evidence pointing to a deep mitochondrial difference between two of the subspecies (Western A. a. alaudipes and A. a. desertorum). My aim in this study was to perform the first comprehensive analysis of the Greater Hoopoe-Lark’s song, to study the vocal variation across its distribution, in order to get insight in its taxonomical status. 82 songs from 27 individuals were sampled with raven pro with the data gathered from open source song-banks. I conclude that compositional differences are present between different populations, this mainly being the different incorporation of a trill in the song. These differences also relate to western and eastern populations of A. a. alaudipes. My results are in line with the molecular evidence, that indicates a species split between African and Middle Eastern/Asian populations, but the sample size and representation of all subspecies in my dataset are insufficient, and the results should therefore be considered to be preliminary and setting a ground for more extensive genetic and vocal analyses.