Publicaties

Capturing complex ecosystem services evaluation with rubrics : A case-study of seaweed cultivation

IJntema, Gerben; Vries, Pepijn de; Lansbergen, Romy; Tonk, Linda; Poelman, Marnix

Samenvatting

With the growing ambitions of implementing low trophic aquaculture, a framework for cohesive and balanced assessment of effects resulting from seaweed cultivation was performed for a hypothetical case study in 2021. As, traditionally, such assessments tend to focus on the negative impacts, it was recommended to also assess the benefits from seaweed cultivation. The concept of ‘Ecosystem services’ (ES) is a sensible construct to express such benefits, as it focuses on the benefits supplied by the ecosystem. The goal of the present study is investigating how these ecosystem services can be included in the comprehensive framework developed last year for a seaweed cultivation case. In order to achieve this, we specifically looked at the project design process, how to map the project needs and how to select or develop the instruments to meet those needs. Roughly, three phases can be distinguished in the study design process: the ideal design phase, where the project specifications required to fulfil the goal of an assessment are defined to ensure the most comprehensive assessment; the realistic design phase, where one performs a reality check on the ideal design, where practical issues, technical issues and resource availability are considered; and finally an adaptive phase: the phase where modifications are made resulting from new insights. In order to facilitate the study design process we developed and applied a so-called ‘rubric’ tool. This rubric is a questionnaire that scores a wide range of elements that are relevant when evaluating ecosystem services for one or more activities (such as seaweed cultivation). This questionnaire considers and addresses elements of ecosystem services impact assessments grouped in the following three aspects: - Which elements are relevant and considered for the study? -What level of detail is required (for these elements)? -How to quantify ES and process the data?. Each sub-question in the rubric is answered with a score between 0 and 5 (where the scale is arbitrary). In the present study, the questionnaire is applied to the case-study goals. But also two contrasting strategies (i.e. application of top-down versus bottom-up methodologies) are included as examples and are evaluated with the rubric for suitability. The top-down strategy uses an existing framework from the EU project Aquacross, which was also used last year to address seaweed cultivation impacts. This framework uses linear cause-effect chains where effects on the ecosystem components are linked to the capacity to supply ecosystem services. The bottom-up methodology is formulated from scratch. It focuses more on the desired outcome, and more attention is paid to benefits resulting from the activities (rather than impacts). Feedback mechanisms are also considered. It should be noted that both methodologies are only available as concepts and are not yet operational. By applying the rubric to both set case-study goals (including ecosystem services in an assessment of the effects from seaweed cultivation) and the proposed methodologies, both results could be compared. It is shown that neither of the two strategies have a 100% match with the case-study goals. This means that neither methodology is preferable at the moment. Also, this means that the methodologies need to be adjusted or the case-study goals need to be revised. In order to make informed decisions on how to proceed in this process a final piece of the puzzle is still missing, which unfortunately is beyond the scope of the present study. - The missing puzzle piece is ‘consequences’. The rubric approach had helped in structuring the project design phase and support underpinning discussions. It made insightful what the study intentions are, and what the proposed methodologies can and cannot offer. It also shows that there is a mismatch between the ideal design and the realistic design. In order to decide which changes (in either case- study goals or strategies to include ecosystem services) are necessary, it is required to know the consequences of these decisions. Several recommendations are made to generalize the assessment of these consequences by linking case-study goals to requirements and their feasibility. This is not further developed in the present study. In conclusion, the rubric approach can be used to score the capacity and limitations of methodological strategy (such as the top-down and bottom-up strategy evaluated here) on one hand and the improve specifications of requirements for a specific case or project on the other hand. As such the approach can be used to evaluate different methodologies, to determine which strategy is most suitable for a specific research question. The approach can also be used to refine research questions or identifying knowledge and data gaps in an early stage of a project. In addition, the approach can be used iteratively during a project execution to manage and adjust the project requirements (and indirectly stakeholder expectations of the project). As such the approach is suitable in each of the three identified study design phases (targeted design, realistic design, adaptive design). In its current form the rubric approach shows promise, but is not yet able to fully support study design choices for evaluating ecosystem services from the seaweed cultivation case from Tonk et al. (2021). For that purpose the approach needs to be extended such that it addresses consequences of design choices, for which recommendations are made.