Eurtophication of the Baltic Sea – consequences for stickleback populations
The environment of the Baltic Sea is currently changing due to eutrophication. Increased input of nutrients is enhancing the growth of filamentous algae and phytoplankton, which changes the structure of the habitats and reduces visibility. The short-term effects of eutrophication are well-known, but the longer term consequences, for ecological and evolutionary processes, are only just beginning to be explored. Our current research shows that eutrophication influences the strength of sexual selection on traits and the reproductive output of populations.
An important question today is which species will be able to adapt to the rapid environmental changes that humans are causing. To answer this question we need to determine which traits and species combinations are favoured in changing environments, in the short term and in the longer term. Because present traits are the product of past conditions, an important step is to determine which ecological conditions favour the evolution of traits that make organisms able to cope with rapid changes, and which constraints restrict their evolution.
The aim of the project is to increase our knowledge of the feedback between ecological and evolutionary processes, and how eco-genetic processes, both in the past and in the present, influence adaptation to changing environments.
The work will focus on:
- The role of ecological conditions in the evolution of phenotypic plasticity in reproductive behaviours.
- The importance of plasticity in reproductive behaviours in facilitating or hindering persistence in changing environments.
Monitoring of threespine stickleback populations (Gasterosteus aculeatus) in the archipelago of Southern Finland has revealed that sticklebacks breeding in eutrophied coastal waters are less parasitized than sticklebacks breeding in clean waters, particularly when it comes to the dominating parasite Schistocephalus solidus. There are two non-mutual explanations for the observed correlation between health and environmental conditions: a) differences in exposure to pathogens, b) differences in resistance to pathogens, which can have both a genetic and an environmental component. The first scenario could arise if the host has adjusted better than the pathogens to eutrophied conditions, resulting in a relatively pathogen free environment, while the second scenario could arise if the pathogens are less virulent (or hosts more resistant) in eutrophied areas, due to hosts leading the host-pathogen co-evolution.
In the current project, we are monitoring Baltic Sea stickleback populations to increase our knowledge on the dependence of host-pathogen interactions on the degree of human induced eutrophication. We relate the findings to the abundance, life-history and environmental requirements of the pathogen species to evaluate the possible causes of the pattern. To reveal the causes, experimental work is performed.
- Determine the correlations between eutrophication and pathogenic infections in threespine stickleback populations in the Baltic Sea.
- Experimentally investigate the causes of the correlations for different pathogens