Marine Seaweed Invasions : the Ecology of Introduced Fucus evanescens

Biological invasions are an important issue of global change and an increased understanding of invasion processes is of crucial importance for both conservation managers and international trade. In this thesis, I have studied the invasion of the brown seaweed Fucus evanescens, to investigate the fate and effect of a perennial, habitat-forming seaweed introduced to a coastal ecosystem. A long-term study of the spread of F. evanescens in Öresund (southern Sweden) showed that the species was able to expand its range quickly during the first 20 years after the introduction, but that the expansion has been slow during the subsequent 30 years. Both in Öresund and in Skagerrak, the species is largely restricted to sites where native fucoids are scarce. Laboratory experiments showed that the restricted spread of F. evanescens cannot be explained by the investigated abiotic factors (wave exposure and salinity), although salinity restricts the species from spreading into the Baltic Sea. Neither did I find evidence for that herbivores or epibiota provide biotic resistance to the invader. On the contrary, F. evanescens was less consumed by native herbivores, both compared to the native fucoids and to F. evanescens populations in its native range, and little overgrown by epiphytes. Instead, the restricted spread may be due to competition from native seaweeds, probably by pre-occupation of space, and the establishment has probably been facilitated by disturbance. The studies provided little support for a general enemy release in introduced seaweeds. The low herbivore consumption of F. evanescens in Sweden could not be explained by release from specialist herbivores. Instead, high levels of chemical anti-herbivore defence metabolites (phlorotannins) could explain the pattern of herbivore preference for different fucoids. Likewise, the low epibiotic colonisation of F. evanescens plants could be explained by high resistance to epibiotic survival. This shows that colonisation of invading seaweeds by native herbivores and epibionts depends on properties of the invading species. The large differences between fucoid species in their quality as food and habitat for epibionts and herbivores imply that invasions of such habitat-forming species may have a considerable effect on a number of other species in shallow coastal areas. However, since F. evanescens did not exclude other fucoids in its new range, its effect on the recipient biota is probably small.

Exercising the self : On the Role of Exercise, Gender and Culture in Physical Self-Perceptions

In modern society, individuals constantly pass judgments on their own body and physical competence as well as that of other people. All too often, the verdict is less favourable. For the person, these physical self-perceptions (PSP) may negatively affect global self-esteem, identity, and general mental well being. The overall aim of this thesis is to examine primarily the role that exercise, but also the roles that gender and culture, play in the formation of PSP. In Study I, using confirmatory factor analyses, strong support for the validity of a first-order, and a second-order hierarchical and multidimensional model of the Physical Self-Perception Profile (PSPP: Fox & Corbin, 1989) was found across three national samples (Great Britain, Sweden and Turkey) of university students. Cross-cultural differences were detected, with the British sample demonstrating higher latent means on all PSPP subdomains except for the physical condition subdomain (Condition), than the Swedish and Turkish samples. In Study II, a higher self-reported exercise frequency was associated with more positive PSP (in particular for Condition) and more importance attributed to PSP in Swedish university students. Males demonstrated higher overall PSPP-scores than females. In Study III, a true-experimental design with randomisation into an intervention and a control group was adopted. Strong support for the effects of an empowerment-based exercise intervention programme on PSP and social physique anxiety (SPA) over six months for adolescent girls was found. The relations of exercise, gender and culture with PSP, SPA and self-esteem are discussed from the standpoints of a variety of theoretical models (the EXSEM-model), and frameworks (self-presentation and objectification theory). The two theories of self-enhancement and skill-development are examined with regard to the direction of the exercise-physical self relationship and motivation for exercise. Arguments for the relevance of exercise and PSP for practitioners in promoting general mental well-being and preventing modern-day diseases are outlined.

On the lifecycle of aerosol particles : Sources and dispersion over Scandinavia

Aerosol particles are likely important contributors to our future climate. Further, during recent years, effects on human health arising from emissions of particulate material have gained increasing attention. In order to quantify the effect of aerosols on both climate and human health we need to better quantify the interplay between sources and sinks of aerosol particle number and mass on large spatial scales. So far long-term, regional observations of aerosol properties have been scarce, but argued necessary in order to bring the knowledge of regional and global distribution of aerosols further. In this context, regional studies of aerosol properties and aerosol dynamics are truly important areas of investigation. This thesis is devoted to investigations of aerosol number size distribution observations performed through the course of one year encompassing observational data from five stations covering an area from southern parts of Sweden up to northern parts of Finland. This thesis tries to give a description of aerosol size distribution dynamics from both a quantitative and qualitative point of view. The thesis focuses on properties and changes in aerosol size distribution as a function of location, season, source area, transport pathways and links to various meteorological conditions. The investigations performed in this thesis show that although the basic behaviour of the aerosol number size distribution in terms of seasonal and diurnal characteristics is similar at all stations in the measurement network, the aerosol over the Nordic countries is characterised by a typically sharp gradient in aerosol number and mass. This gradient is argued to derive from geographical locations of the stations in relation to the dominant sources and transport pathways. It is clear that the source area significantly determine the aerosol size distribution properties, but it is obvious that transport condition in terms of frequency of precipitation and cloudiness in some cases even more strongly control the evolution of the number size distribution. Aerosol dynamic processes under clear sky transport are however likewise argued to be highly important. Southerly transport of marine air and northerly transport of air from continental sources is studied in detail under clear sky conditions by performing a pseudo-Lagrangian box model evaluation of the two type cases. Results from both modelling and observations suggest that nucleation events contribute to integral number increase during southerly transport of comparably clean marine air, while number depletion dominates the evolution of the size distribution during northerly transport. This difference is largely explained by different concentration of pre-existing aerosol surface associated with the two type cases. Mass is found to be accumulated in many of the individual transport cases studied. This mass increase was argued to be controlled by emission of organic compounds from the boreal forest. This puts the boreal forest in a central position for estimates of aerosol forcing on a regional scale.

Global trade, food production and ecosystem support : Making the interactions visible

Modern food production is a complex, globalized system in which what we eat and how it is produced are increasingly disconnected. This thesis examines some of the ways in which global trade has changed the mix of inputs to food and feed, and how this affects food security and our perceptions of sustainability. One useful indicator of the ecological impact of trade in food and feed products is the Appropriated Ecosystem Areas (ArEAs), which estimates the terrestrial and aquatic areas needed to produce all the inputs to particular products. The method is introduced in Paper I and used to calculate and track changes in imported subsidies to Swedish agriculture over the period 1962-1994. In 1994, Swedish consumers needed agricultural areas outside their national borders to satisfy more than a third of their food consumption needs. The method is then applied to Swedish meat production in Paper II to show that the term “Made in Sweden��� is often a misnomer. In 1999, almost 80% of manufactured feed for Swedish pigs, cattle and chickens was dependent on imported inputs, mainly from Europe, Southeast Asia and South America. Paper III examines ecosystem subsidies to intensive aquaculture in two nations: shrimp production in Thailand and salmon production in Norway. In both countries, aquaculture was shown to rely increasingly on imported subsidies. The rapid expansion of aquaculture turned these countries from fishmeal net exporters to fishmeal net importers, increasingly using inputs from the Southeastern Pacific Ocean. As the examined agricultural and aquacultural production systems became globalized, levels of dependence on other nations’ ecosystems, the number of external supply sources, and the distance to these sources steadily increased. Dependence on other nations is not problematic, as long as we are able to acknowledge these links and sustainably manage resources both at home and abroad. However, ecosystem subsidies are seldom recognized or made explicit in national policy or economic accounts. Economic systems are generally not designed to receive feedbacks when the status of remote ecosystems changes, much less to respond in an ecologically sensitive manner. Papers IV and V discuss the problem of “masking” of the true environmental costs of production for trade. One of our conclusions is that, while the ArEAs approach is a useful tool for illuminating environmentally-based subsidies in the policy arena, it does not reflect all of the costs. Current agricultural and aquacultural production methods have generated substantial increases in production levels, but if policy continues to support the focus on yield and production increases alone, taking the work of ecosystems for granted, vulnerability can result. Thus, a challenge is to develop a set of complementary tools that can be used in economic accounting at national and international scales that address ecosystem support and performance. We conclude that future resilience in food production systems will require more explicit links between consumers and the work of supporting ecosystems, locally and in other regions of the world, and that food security planning will require active management of the capacity of all involved ecosystems to sustain food production.

Den utvärdera(n)de staten : Utvärderingens institutionalisering på den högre utbildningens område

In recent years evaluation has become a very important element in the public administration. The Swedish state administration to a significant extent both evaluates and is evaluated. This means that the evaluating state is at the same time the evaluated state. In this dissertation the institutionalization of evaluation is studied in a field within which this development has been particularly lively and interesting, namely the field of higher education. The dissertation focuses on evaluation activity that has been carried out in conjunction with central public authorities within higher education: the Office of the Chancellor of the Universities and Colleges in Sweden, the National Swedish Board of Universities and Colleges, and the Office of the University Chancellor, and encompasses the period 1964-1995. A newly revived research tradition within political science – historical institutionalism – is used as a perspective and a methodology. Since the application of this tradition has not yet been fully tested, another purpose is to examine the practical utility of this analytical tool and the kind of knowledge that it produces. The dissertation thereby combines the fields of education policy, evaluation research and institutional theory. The beginning of the institution has been dated to the end of the 1960s and beginning of the 1970s. In the dissertation the forces behind the initiation of the institution are taken up. Events and developments in the field that have influenced the further development of the institution have been identified and analyzed. Developments reveal that the institution has been stable during the entire period of time under study, despite some changes. The use of historical institutionalism as a perspective and methodology has proven satisfactory on a general level. However, special solutions have been required as problems and ambiguities have arisen. The dissertation concludes with reflections on the practical utility of historical institutionalism in political science research.

Essays on Personnel Economics and Gender Issues

This thesis consists of four self-contained essays in economics. Tournaments and unfair treatment. This paper introduces the negative feelings associated with the perception of being unfairly treated into a tournament model and examines the impact of these perceptions on workers’ efforts and their willingness to work overtime. The effect of unfair treatment on workers’ behavior is ambiguous in the model in that two countervailing effects arise: a negative impulsive effect and a positive strategic effect. The impulsive effect implies that workers react to the perception of being unfairly treated by reducing their level of effort. The strategic effect implies that workers raise this level in order to improve their career opportunities and thereby avoid feeling even more unfairly treated in the future. An empirical test of the model using survey data from a Swedish municipal utility shows that the overall effect is negative. This suggests that employers should consider the negative impulsive effect of unfair treatment on effort and overtime in designing contracts and determining on promotions. Late careers in Sweden between 1970 and 2000. In this essay Swedish workers’ late careers between 1970 and 2000 are studied. The aim is to examine older workers’ career patterns and whether they have changed during this period. For example, is there a difference in career mobility or labor market exiting between cohorts? What affects the late career, and does this differ between cohorts? The analysis shows that between 1970 and 2000 the late careers of Swedish workers comprised of few job changes and consisted more of “trying to keep the job you had in your mid-fifties” than of climbing up the promotion ladder. There are no cohort differences in this pattern. Also a large fraction of the older workers exited the labor market before the normal retirement age of 65. During the 1970s and first part of the 1980s, 56 percent of the older workers made an early exit and the average drop-out age was 63. During the late 1980s and the 1990s the share of old workers who made an early exit had risen to 76 percent and the average drop-out age had dropped to 61.5. Different factors have affected the probabilities of an early exit between 1970 and 2000. For example, skills did affect the risk of exiting the labor market during the 1970s and up to the mid-1980s, but not in the late 1980s or the 1990s. During the first period old workers in the lowest occupations or with the lowest level of education were more likely to exit the labor market than more highly skilled workers. In the second period old workers at all levels of skill had the same probability of leaving the labor market. The growth and survival of establishments: does gender segregation matter? We empirically examine the employment dynamics that arise in Becker’s (1957) model of labor market discrimination. According to the model, firms that employ a large fraction of women will be relatively more profitable due to lower wage costs, and thus enjoy a greater probability of surviving and growing by underselling other firms in the competitive product market. In order to test these implications, we use a unique Swedish matched employer-employee data set. We find that female-dominated establishments do not enjoy any greater probability of surviving and do not grow faster than other establishments. Additionally, we find that integrated establishments, in terms of gender, age and education levels, are more successful than other establishments. Thus, attempts by legislators to integrate firms along all dimensions of diversity may have positive effects on the growth and survival of firms. Risk and overconfidence – Gender differences in financial decision-making as revealed in the TV game-show Jeopardy. We have used unique data from the Swedish version of the TV-show Jeopardy to uncover gender differences in financial decision-making by looking at the contestants’ final wagering strategies. After ruling out empirical best-responses, which do appear in Jeopardy in the US, a simple model is derived to show that risk preferences, the subjective and objective probabilities of answering correctly (individual and group competence), determine wagering strategies. The empirical model shows that, on average, women adopt more conservative and diversified strategies, while men’s strategies aim for the greatest gains. Further, women’s strategies are more responsive to the competence measures, which suggests that they are less overconfident. Together these traits make women more successful players. These results are in line with earlier findings on gender and financial trading.