A multi-criteria decision analysis model for ship biofouling management in the Baltic Sea.

Biofouling of ship hulls form a vector for the introduction of non-indigenous organisms worldwide. Through increasing friction, the organisms attached to ships' hulls increase the fuel consumption, leading to both higher fuel costs and air emissions. At the same time, ship biofouling management causes both ecological risks and monetary costs. All these aspects should be considered case-specifically in the search of sustainable management strategies. Applying Bayesian networks, we developed a multi-criteria decision analysis model to compare biofouling management strategies in the Baltic Sea, given the characteristics of a ship, its operating profile and operational environment, considering the comprehensive environmental impact and the monetary costs. The model is demonstrated for three scenarios (SC1-3) and sub-scenarios (A-C), comparing the alternative biofouling management strategies in relation to NIS (non-indigenous species) introduction risk, eco-toxicological risk due to biocidal coating, carbon dioxide emissions and costs related to fuel consumption, in-water cleaning and hull coating. The scenarios demonstrate that by the careful consideration of the hull fouling management strategy, both money and environment can be saved. We suggest biocidal-free coating with a regular in-water cleaning using a capture system is generally the lowest-risk option. The best biocidal-free coating type and the optimal in-water cleaning interval should be evaluated case-specifically, though. In some cases, however, biocidal coating remains a justifiable option.

Developing a conceptual influence diagram for socio-eco-technical systems analysis of biofouling management in shipping - A Baltic Sea case study.

Ship hulls create a vector for the transportation of harmful non-indigenous species (NIS) all over the world. To sustainably prevent NIS introductions, the joint consideration of environmental, economic and social aspects in the search of optimal biofouling management strategies is needed. This article presents a multi-perspective soft systems analysis of the biofouling management problem, based on an extensive literature review and expert knowledge collected in the Baltic Sea area during 2018-2020. The resulting conceptual influence diagram (CID) reveals the multidimensionality of the problem by visualizing the causal relations between the key elements and demonstrating the entanglement of social, ecological and technical aspects. Seen as a boundary object, we suggest the CID can support open dialogue and better risk communication among stakeholders by providing an illustrative and directly applicable starting point for the discussions. It also provides a basis for quantitative management optimization in the future.

Spatial aspects of the dioxin risk formation in the Baltic Sea: A systematic review.

Dioxins have been an inconvenience to the Baltic Sea ecosystem for decades. Although the concentrations in the environment and biota have continuously decreased, dioxins still pose a risk to human health. The risk and its formation vary in different parts of the Baltic Sea, due to variability in the environmental and societal factors affecting it. This paper presents a systematic literature review and knowledge synthesis about the regional dioxin risk formation in four sub-areas of the Baltic Sea and evaluates, whether systemic approach changes our thinking about the risk and its effective management. We studied the dioxin flux from atmospheric deposition to the Baltic Sea food webs, accumulation to two commercially and culturally important fish species, Baltic herring (Clupea harengus membras) and Baltic salmon (Salmo salar), and further to risk group members of four Baltic countries. Based on 46 studies, we identified 20 quantifiable variables and indexed them for commensurable regional comparison. Spatial differences in dioxin pollution, environmental conditions, food web dynamics, and the following dioxin concentrations in herring and salmon, together with fishing and fish consumption, affect how the final health risk builds up. In the southern Baltic Sea, atmospheric pollution levels are relatively high and environmental processes to decrease bioavailability of dioxins unfavorable, but the growth is fast, which curb the bioaccumulation of dioxins in the biota. In the North, long-range atmospheric pollution is minor compared to South, but the local pollution and slower growth leads to higher bioaccumulation rates. However, based on our results, the most remarkable differences in the dioxin risk formation between the areas arise from the social sphere: the emissions, origin of national catches, and cultural differences in fish consumption. The article suggests that acknowledging spatial characteristics of socio-ecological systems that generate environmental risks may aid to direct local focus in risk management.