Co-Supervisors: Tom Andersen and Simon Hassel? Kline
This master’s project will be integrated into the cross-disciplinary “Coastal Ecosystems under anthropogenic pressures” research project.
Phytoplankton are primary producers and the basis of most food webs in the ocean. Changes within the phytoplankton community are likely to have effects throughout the remaining food web and ecosystem, which in turn may affect the overall resilience of marine ecosystems to changing conditions.
The phytoplankton composition and abundance vary strongly through the year. The yearly spring bloom is a dominant feature of the population growth pattern of phytoplankton in temperate waters and is an event that has triggering effects throughout the remaining food web and ecosystem. The timing of the early phytoplankton spring bloom is usually initiated through increased light availability or increased stratification of the water column, as nutrient as a rule is not limiting for growth after the winter-mixing of the water column.
Lunds?r et al. (2022) found that since 2013 the phytoplankton spring bloom in the Inner Oslofjord has shifted from two peaks during spring (first main peak in February-March and a second, smaller peak in May-June) to two equally large peaks that occur in March-May. Skeletonema and Chaetoceros are among the dominating diatom genera during the spring bloom in the Oslofjord, and the observed shift in the delay of the spring bloom was proposed to be largely driven by the reduction of Skeletonema biomass in Inner Oslofjorden (Lunds?r et al., 2022). Additionally, they have shown that the relative abundance of mixotrophic and heterotrophic dinoflagellates in relation to autotrophic diatoms during the spring bloom has increased over the last ca 15 years in Inner Oslofjorden. The explanations to these changes are unknown.
Project description
In this project, we aim to investigate the dynamics of common spring bloom diatoms in the Oslofjord experimentally. The student will conduct common garden (multiple species under shared conditions) growth experiments with diatoms in culture to see how the species composition varies according to the tested environmental conditions (such as salinity, temperature and light, +/- grazers). We will also attempt to use the Planktoscope (https://www.planktoscope.org) (Thibaut et al., 2022), an open-platform digital imaging microscope to quantify and identify how the species composition varies throughout the common garden growth experiments and grazing experiments.
Possible questions to be answered:
- Is the species composition of phytoplankton changing in response to the tested parameters during the common garden growth experiments?
- Can the observed reduction of diatom biomass versus dinoflagellates in the spring bloom be explained by any of the tested conditions?
- Can the Planktoscope reliably quantify cell abundances in a phytoplankton common garden growth experiment?
Learning Outcomes
You will have the opportunity to:
- Join the monthly sampling cruises conducted in the Oslofjorden.
- Collaborate with a PhD-student, postdoc and other master’s students participating in the “Coastal Ecosystems Dynamics under anthropogenic pressures” research project.
- Collect data that may be used in a scientific publication, along with a potential co-authorship.
You will learn:
- Sampling methods used in the field to collect plankton samples.
- How to plan, conduct and follow an experimental plankton study.
- How to interpret results from growth and grazing experiments.
- How to quantify phytoplankton biomass through traditional microscopy and an imaging flow microscope.
What we offer
We offer an inclusive and stimulating research environment where the student is encouraged to join the research group activities and engage with other students and researchers in the group.
References:
Biddanda, B., Dila, D., Weinke, A., Mancuso, J., Villar-Argaiz, M., Medina-Sánchez, J. M., González-Olalla, J. M., & Carrillo, P. (2021). Housekeeping in the hydrosphere: Microbial cooking, cleaning, and control under stress. Life, 11(2), 152.
Caron, D. A., Countway, P. D., Jones, A. C., Kim, D. Y., & Schnetzer, A. (2012). Marine protistan diversity. Annual review of marine science, 4(1), 467-493.
Knoll, A. H. (1992). The early evolution of eukaryotes: a geological perspective. Science, 256(5057), 622-627.
Lunds?r, E., Stige, L. C., S?rensen, K., & Edvardsen, B. (2020). Long-term coastal monitoring data show nutrient-driven reduction in chlorophyll. Journal of Sea Research, 164, 101925.
Lunds?r, E., Eikrem, W., Stige, L. C., Engesmo, A., Stadnicze?ko, S. G., & Edvardsen, B. (2022). Changes in phytoplankton community structure over a century in relation to environmental factors. Journal of Plankton Research.
Thibaut, P., Adam, G. L., Fabien, L., Hongquan, L., David Le, G., Sébastien, C., Colomban de, V., & Manu, P. (2022). PlanktoScope: Affordable Modular Quantitative Imaging Platform for Citizen Oceanography. Frontiers in Marine Science, 9.