Science Blog: Geodiversity of the Baltic Sea

Anu Kaskela, Geologist

During recent years, the term ‘geodiversity’ has been used in parallel with biodiversity to advance the integrated management of the environment and to emphasize that ecosystems consists of both biotic and abiotic components. Geodiversity includes the natural range of geological, geomorphological, and soil features and their assemblages, relationships, properties, interpretations, and systems (Gray, 2004). So far, geodiversity has primarily been quantified in land areas with the help of geographical information system (GIS) methods. A recent study by the Geological Survey of Finland applied these methods to a seabed environment to quantify the geodiversity of the Baltic Sea, identify areas with high geodiversity, and draw conclusions on the contributing geological processes.

The basin-wide study was performed by analyzing broad-scale geological datasets in the GIS environment. The bedrock geology, seabed substrate, and seabed structures were considered as the main datasets constituting seabed geodiversity, which was analyzed using three parameters: the richness, patchiness, and geodiversity index. In addition, the geodiversity patterns over the whole basin were analyzed against potential drivers describing the glacial influence and post-glacial sedimentation and erosion conditions.

It was shown that the seafloor conditions and geodiversity of the Baltic Sea are not uniform but vary between sub-basins (Fig. 1). Within the Baltic Sea, geodiversity generally increases from south to north, from the open sea to a high shoreline density, and from sedimentary rock to crystalline basement. The overall geological landscape of the Baltic Sea is characterized by plains and basins, whereas other geomorphic features, such as elevations and valleys, are typical of certain sub-regions. The bedrock type, glacial history, and ongoing processes influence the geomorphic content and thus affect the distribution of geodiversity. In particular, archipelago areas within a crystalline basement indicate high geodiversity levels. Archipelagos with dense occurrences of rocky islands and reefs are distinctive of the Baltic Sea. These archipelagos display dynamic seafloor conditions, where seafloor properties and processes change within very short distances.

The results stress the significance of the geological past in shaping the seafloor conditions of the Baltic Sea. The pre-glacial and glacial influence on the broad-scale geodiversity patterns of the Baltic Sea is apparent. For example, the bedrock morphology, which was considered to influence the current geodiversity distribution, reflects the fracture and jointing patterns of the lithology, developed over long timescales. The results motivate the inclusion of a long-term perspective when analyzing geodiversity and highlight the importance of providing spatial data on the geological processes of the past.

It is emphasized that seabed geological features and geodiversity should be acknowledged in marine spatial planning, because they have intrinsic value and they provide several abiotic ecosystem services. Maps of seafloor geodiversity can guide the placement of certain anthropogenic activities, such as underwater constructions and sand extraction, and the development of frameworks to monitor the environmental impacts. The survey needs in complex seafloor environments with high geodiversity most likely differ from those in homogeneous areas. In addition, geodiversity can be linked to habitat complexity and thus to biodiversity.

Marine areas hold promise for economic growth, innovations, and human welfare. For example, the Organization for Economic Cooperation and Development (OECD, 2016) has projected that the ocean economy could more than double its contribution to global value and reach over USD 3 trillion by 2030. Furthermore, the European Commission has adopted a concept of Blue Growth to strengthen its maritime sector. However, marine areas already face multiple threats due to human activities, e.g. over-exploitation and pollution. One of the key issues in boosting long-term maritime economic development is to ensure that it is done in a sustainable manner. Knowledge of the distribution of seabed geodiversity supports the sustainable use of marine resources by informing scientists, marine spatial planners, and managers about abiotic conservation values and the complexity of the seabed environment.

This study, “Seabed geodiversity in a glaciated shelf area, the Baltic Sea” by Kaskela & Kotilainen, was published in Geomorphology in October 2017 (Vol 295, pages 419-435). (http://www.sciencedirect.com/science/article/pii/S0169555X1730291X?via%3Dihub)

Figure 1. Geodiversity distribution of the Baltic Sea based on the geodiversity index (A), patchiness (B), and richness (C). The geodiversity has been classified based on quantiles: Q1 (<25%), Q2 (25%–50%), Q3 (50%–75%), and Q4 (>75%). (Coastline: European Environmental Agency, 2013). Reprinted from Kaskela & Kotilainen (2017), with permission from Elsevier.

References and other readings:

Gray, M. 2004. Geodiversity. Valuing and Conserving Abiotic Nature. Wiley, Chichester. 448 p.

OECD, 2016. The Ocean Economy in 2030. OECD Publishing, Paris. 256 p. http://dx.doi.org/10.1787/9789264251724-en

Kaskela, A. M., Kotilainen, A. T., Al-Hamdani, Z., Leth, J. & Reker, J. 2012. Seabed geomorphic features in a glaciated shelf of the Baltic Sea. Estuarine, Coastal and Shelf Science 100, 150–161. ISSN 0272-7714, http://dx.doi.org/10.1016/j.ecss.2012.01.008.

Kaskela, A. M., Rousi, H., Ronkainen, M., Orlova, M., Babin, A., Gogoberidze, G., Kostamo, K., Kotilainen, A. T., Neevin, I., Ryabchuk, D., Sergeev, A. & Zhamoida, V. 2017. Linkages between benthic assemblages and physical environmental factors: The role of geodiversity in Eastern Gulf of Finland ecosystems. Continental Shelf Research 142, 1-13. ISSN 0278-4343, https://doi.org/10.1016/j.csr.2017.05.013.

Anu Kaskela

Text: Anu Kaskela

Anu Kaskela (PhD) works at the Marine Geology Unit of the Geological Survey of Finland. She is a geologist with experience of marine geological surveys, GIS, spatial analysis, and data harmonization, among other areas. She has worked in several international and multidisciplinary research projects related to marine environments.