• Viikinkaari 1, Biocentre 3

    00790 Helsinki


  • Viikinkaari 5, Biocenter 2

    00790 Helsinki


  • Viikinkaari 1, Biokeskus 3

    00790 Helsinki


1983 …2023

Forskningsoutput per år

Personlig profil

Information om forskning och undervisning

Research profile


As a research group leader Dr Ojala has a wide experience in aquatic freshwater research, especially in truly multidisciplinary carbon cycling studies in the context of climate change. She focuses strongly on field work and her field measurements are done in the SMEAR II station (Station for Measuring Forests – Atmosphere Relations) in the Hyytiälä Forestry Field Station where there is a heavily instrumented state-of-the-art measuring platform called Lake-SMEAR for continuous lake measurements. The studies are also linked to ICOS, Integrated Carbon Observation System, which is a large European research infrastructure forquantifying and understanding the greenhouse gas balance of the European continent and of adjacent regions. The field studies are done in collaboration with the atmospheric physicists and forest ecologists of the University of Helsinki and thus as a part of the Finnish CoE, which is presently called‘Centre of Excellence in Atmospheric Science – From Molecular and Biological processes to The Global Climate (ATM)’, led by Academy professor Markku Kulmala. Dr Ojala’s most important collaborators are Academy professor Timo Vesala (University of Helsinki), Professor Jaana Bäck (University of Helsinki) and Professor Jukka Pumpanen (University of Eastern Finland). The objective of Ojala’s studies is to fully integrate the lacustrine studies with atmospheric and forest ecological studies, i.e. besides the common shared idea there is an aim to use the same methodologies, i.e. for instance adopt techniques used in forest ecology and ecophysiology in studies of algal ecology. Globally, this kind of integration is unique. Another objective is to get time series of continuous measurements long enough to reveal true seasonal and annual patterns of the phenomena under study. Thus, lakes are accepted as fully open, boundless systems which are much more dynamic entities than could be anticipated on the basis of traditional approaches where samples are taken once a week or even once a month. In future the scientific interfaces will be supplemented with more rigorous studies on physical interfaces; the focus has been on lake-atmosphere processes but is being extended to thermocline, sediment-water –interface and riparian zone, i.e. the interface between the lake and the forest ecosystem. In general, the studies can be said to follow the principle ‘act locally, think globally’ and they are based on high creativity of the leader as well as the team as a whole resulting in the apparent, but non-intentional aim ‘to be the first’. This pioneer spirit has become clear e.g. in the riverine studies where the large River Kymijoki in southern Finland has been studied first time in the world with micrometeorological methods. The group has also been among the first to study BVOCs - important for aerosol formation and thus climate - not only from boreal lakes, but from lakes in general and most likely the first one to apply quantum chemistry in limnological studies.


The second part of the research is about food web structure and functioning and aims at revealing the nutritional modes of algae and especially the true role of mixotrophs which are functionally powerful organisms. Mixotrophs act as producers and consumers and are thus capable of modifying food webs, affecting nutrient cycling. However, this role has been long overlooked since aquatic unicellular primary producers have been considered to be purely autotrophic. However, most of them are mixotrophic and use inorganic as well as organic carbon sources. The opposite is also true since there are components in the plankton community usually considered purely heterotrophic, but which are actually kleptoplastidic mixotrophs using stolen chloroplasts. The degree of mixotrophy varies among species and according to environmental conditions, and it also affects the nutritional value of the organisms, e.g., the amount of polyunsaturated fatty acids (PUFAs), which are essential for all consumers from zooplankton and fish to humans. The main objective in this study line, carried out in collaboration with Dr Elina Peltomaa, a post doc in the group, is to quantify the amount of organic and inorganic carbon as well as nitrogen, phosphorus and iron that are taken up by mixotrophs using radioisotope or stable isotope labeling. Besides basic research there is activity in applied algological research, i.e. there is aim at integrating basic and applied algological research, which is a globally unique approach. Microalgae produce high value metabolites such as lipids, vitamins and pigments, and these can be utilized in industrial applications. For instance, PUFAs are used as nutritional additives and in proactive health foods, while pigments are used as antioxidants and coloring in food and medicines. Additionally, microalgae are suitable as such as nutritional supplements and as feed because of their high protein and carbohydrate contents. The biomass composition of selected microalgae strains is being characterized with the objective to increase the microalgae production of omega fatty acids and pigments by regulating growth conditions. The aim is to generate research data that can be used in practical applications. This research line is carried out in close co-operation with Professor Martin Romantschuk and his group which collaborates e.g. with food and feed scientists from University of Helsinki. This line also includes research where the abilities of mixotrophs to use organic compounds are utilized and the algae are grown in different kind of waste fractions thus paving the road to circular economy. For the integrated laboratory experiments in scales ranging from small bottles to pilot scale growth units the objective is to set up a modern algological research laboratory which can be seen as a research facility serving not only a single department but the whole university. For that we have already access to a wide array of apparatus ranging from growth chambers and pilot scale photobioreactors to flow cytometer, GC MS, qPCR etc. The facility is now under construction. The intention is that the Algological Research Laboratory (ALGOLAB) will be a part of the European research network AnaEE which is a research infrastructure for experimental manipulation of managed and unmanaged terrestrial and aquatic ecosystems.


Teaching profile


Since as an academic Dr Ojala has specialized in aquatic ecosystems, i.e. aquatic ecosystem ecology and biogeochemistry, her teaching also has a strong focus on these issues. She is motivated, highly enthusiastic and dedicated university teacher with very good interpersonal and communication skills which help to create good working relationships with students; this is a necessity in interactive, efficient teaching, which is based on coaching type approach. She has extended her passion in multidisciplinary research, where she combines aquatic studies with forest ecology and atmospheric physics, into her teaching; recently she has started truly science based MSc level teaching in a field course together with the forest scientists. Altogether she has > 30 years teaching experience at the University of Helsinki covering all academic levels, i.e. from the first year BSc level introductory courses to MSc and finally PhD level training. Dr Ojala has been the responsible teacher in ca. 70 courses and altogether she has taught in ca. 100 courses and seminars, along with numerous supervised written assessments and BSc theses. The course titles range from ‘Fundamentals of Ecology’ and ‘Advanced Course in Zooplankton ecology’ to ‘Wetland Ecology’, ‘Biogeochemistry and Eco- and Geohydrology’, ‘Lakes and Greenhouse Gases’ finally to ‘Field Course in Environmental Research’. She is accustomed to working in a multidisciplinary academic environment and emphasizes the benefits of open-mindedness in her teaching.  She has been especially successful in training MSc as well as PhD students; she has supervised 6 PhD students, one licentiate and 25 MSc students and presently she has 6 PhD students and 5 MSc students under her supervision. She is in strong favor of multidisciplinary collaboration and thus, majority of these supervisions are jointly with the scientists from the Department of Forest Sciences and Department of Physics. Besides, she is acting as a mentor for three young post-doctoral scientist. She is also a member of advisory board of two PhD students in aquatic sciences and has been the external examiner for 7 PhD theses, member of the evaluation panel for one and opponent for one PhD thesis. In addition, she has evaluated one docentship candidate. She has also been the member of the committee for assessment of academic teaching skills, Faculty of Biological and Environmental Sciences, University of Helsinki in 2010-2013 and is presently a member of the same committee nominated for the period 2011-2017. She also holds the memberships of the Executive Board of DENVI multidisciplinary doctoral program of University of Helsinki and the Executive Board of ATM-DP doctoral program of atmospheric sciences of University of Helsinki. She has also provided her expertise outside academia by being the chairperson of the working group ‘Research and Education’ in Finnish Water Forum (FWF).



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