TURUN YLIOPISTON MERENKULKUALAN KOULUTUS- JA TUTKIMUSKESKUKSEN JULKAISUJA PUBLICATIONS FROM THE CENTRE FOR MARITIME STUDIES UNIVERSITY OF TURKU A 50 2009 NATURAL SCIENCE IN THE BOTHNIAN SEA DURING 1975-2008: A REVIEW Reetta Saikku, Minna Alhosalo, Sari Repka & Anne Erkkilä TURUN YLIOPISTON MERENKULKUALAN KOULUTUS- JA TUTKIMUSKESKUKSEN JULKAISUJA PUBLIKATIONER AV SJÖFARTSBRANSCHENS UTBILDNINGS- OCH FORSKNINGSCENTRAL VID ÅBO UNIVERSITET PUBLICATIONS FROM THE CENTRE FOR MARITIME STUDIES UNIVERSITY OF TURKU A 50 2009 NATURAL SCIENCE IN THE BOTHNIAN SEA DURING 1975-2008: A REVIEW Reetta Saikku, Minna Alhosalo, Sari Repka & Anne Erkkilä Turku 2009 SARJAN PÄÄTOIMITTAJA / EDITOR-IN-CHIEF Juhani Vainio JULKAISIJA / PUBLISHER: Turun yliopisto / University of Turku MERENKULKUALAN KOULUTUS- JA TUTKIMUSKESKUS CENTRE FOR MARITIME STUDIES Veistämönaukio 1–3 FI–20100 TURKU, FINLAND Puh. / Tel. +358 (0)2 281 3300 Fax +358 (0)2 281 3311 http://mkk.utu.fi Painosalama Oy Turku 2009 ISBN 978–951–29–4129–2 (paperback) ISBN 978–951–29–4130–8 (PDF) ISSN 1456–1816 FOREWORD The Bothnian Sea, as a shallow body of brackish water and part of the northern-most limb of the Baltic, is a unique environment differing from the rest of the Baltic. Due to this uniqueness it is a region which needs to be studied in itself, for example for the mitigation of climate change impacts and the effects of eutrophication, as research results from other parts of the Baltic may not be relevant here. In this study through reviewing the past 33 years of research on the Bothnian Sea, we have identified gaps in the current knowledge allowing us to provide recommendations for future research focus. The Bothnian Sea has so far lacked a unified academic research strategy and mainly single research entities have been published over the years. What we now need is the big picture and a multidisciplinary research strategy to tackle problems such as eutrophication to ensure a sustainable future for the region and the people inhabiting its shores. This study was conducted at the University of Turku Centre for Maritime Studies Pori Unit as part of the natural sciences environmental research development project of the coastal region of Satakunta (Luonnontieteellisen ympäristötutkimuksen kehittäminen Satakunnassa, LYKS). This project is funded by the Regional Council of Satakunta, the University of Turku and the City of Pori. Turku 4th November, 2009 Anne Erkkilä Director Centre for Maritime Studies SUMMARY The Baltic Sea is one of the most studied areas in the world. However, parts of its northernmost reach, the Bothnian Sea, seem to be under represented in the natural scientific literature compared to other parts of the Baltic. The Bothnian Sea represents a unique inland sea environment for the scientific community to study due to its shallowness and low salinity. The natural sciences research carried out on the Bothnian Sea has been reviewed between 1975 and 2008. This time period was chosen to continue on from an earlier review paper ending in 1974. Along with the number of papers published the goal was also to review the content of the papers, indentifying dominating themes to evaluate gaps in the current knowledge on the Bothnian Sea and provide recommendations for topics of future research focus. In a classification into specific research topics biodiversity was the leading research focus followed by chemical and physical oceanography, pollution and toxins, and fish biology and fisheries. The current good condition of the Bothnian Sea is highly valued with its historically less eutrophic and clearer waters when compared to the Baltic. However, today the Bothnian Sea is facing eutrophication resulting from nutrient-rich water transported by the many rivers draining into it from Sweden and Finland making it an area in need of protection and preservation. More human activity will also concentrate on the Bothnian Sea in the future. Therefore the use of the sea and its coastal areas must be planned carefully to minimize the harmful effects of this increasing human activity. To achieve this more information is needed for the basis of Integrated Coastal Zone Management (ICZM) and maritime spatial planning (MSP). For example, for the Bothnian Sea the information on the underwater nature which is essential for ICZM is so far missing to a large extent. Specific biological, chemical and physical oceanographic information is needed to combine with economic analyses and environmental policies regarding this region. More research of a multidisciplinary nature is required on the unique Bothnian Sea environment and this we feel is best achieved through a joint Finnish-Swedish research strategy. CONTENTS 1 Introduction .............................................................................................................. 7 2 Methodology ............................................................................................................. 9 2.1 Territorial definition ......................................................................................... 9 2.2 ISI Web of Knowledge ..................................................................................... 9 2.3 Time period/scale ............................................................................................. 9 2.4 Other definitions ............................................................................................. 10 2.5 Division into themes ....................................................................................... 10 2.6 Review database ............................................................................................. 10 3 Results .................................................................................................................... 11 3.1 List of journals ................................................................................................ 11 3.2 Authors ........................................................................................................... 12 3.3 Distribution of articles between 1975-2008 ................................................... 12 3.4 Times cited ..................................................................................................... 13 3.5 International collaboration .............................................................................. 13 3.6 Themes ........................................................................................................... 14 3.6.1 Scientific disciplines ................................................................................... 14 3.6.2 Thematic research focus ............................................................................. 15 4 Discussion ............................................................................................................... 17 4.1 Research volume and quantity ........................................................................ 17 4.2 Regional comparison ...................................................................................... 17 4.3 Research themes ............................................................................................. 18 5 Conclusions ............................................................................................................ 21 6 References .............................................................................................................. 22 Natural science in the Bothnian Sea during 1975-2008: a review 7 1 INTRODUCTION The Gulf of Bothnia is the northernmost section of the Baltic Sea. It is situated between the coast of Finland to the east and the coast of Sweden to the west. The Gulf of Bothnia is divided into two inland seas at the narrow passage of Kvarken. The Kvarken separates the inner (northernmost) part of the gulf, the Bothnian Bay, from the southern Bothnian Sea (see Figure 1). The Bothnian Sea, with a mean depth of 60m, is a body of brackish water reaching south to the Archipelago Sea and Sea of Åland. It has a salinity averaging 5-6 per mille, a ragged coastline and a gradually deepening continental slope with slow sedimentation rates (Voipio, 1981, Granö et al, 1999). Due to the physical barriers set by the coastline, the groups of islands in the south as well as the shape of the seabed, the nutrient-rich bottom water from the Baltic cannot flow into the Bothnian Sea. This constitutes the main reason why eutrophication has not yet become for the Bothnian Sea the major problem which it is for the Baltic. However, the situation in the Bothnian Sea is now beginning to change as a result of the nutrient-rich water draining into the Bothnian Sea from the many Swedish and Finnish rivers (Lundberg et al, 2009, HELCOM, 2009). Figure 1.1 Map of the Bothnian Sea and the Bothnian Bay (together making up the Gulf of Bothnia) divided by the Kvarken. The study area of this review paper is defined by the coastlines and the 60.5°N and 63.5°N lines of latitude. While the Bothnian Sea is an economically important region with the majority of herring in the Baltic being caught in the Bothnian Sea (Lehtonen, 2005, Parmanne, 1998), it has generally not been the focus of much scientific effort. The reason for this could be its rather good condition. The same is true for monitoring efforts as there are fewer monitoring sites, temporally and spatially, in the Bothnian Sea than in the smaller Archipelago Sea (HELCOM, 2009). This has made it difficult to conduct spatially 8 Saikku, Alhosalo, Repka & Erkkilä representative surveys of the Bothnian Sea when the