Spatial tools to calculate cumulative impact assessments on the environment (CIA) are important contributors to the implementation of an ecosystem-based approach to maritime spatial planning (MSP). Ecosystem dynamics are increasingly important to understand as the activities and pressures in marine areas increase. Results from the application of a new training set for the CIA tool MYTILUS, developed in capacity-building MSP projects for active learning environments, illustrate important points on how the CIA method can be used in systematic scenario design. The feedback from its use in an online PhD course outlines how the training set successfully enables researchers from different disciplines and different parts of the world to meet the CIA approach with such interest and understanding that it enables them to highlight the strengths as well as the shortcomings of the tool interface, tool capabilities, and CIA method, even when none of these researchers are CIA experts. These promising results are presented in this paper and advocate for the increasing use of MYTILUS and similar CIA tools in MSP stakeholder sessions where no preliminary CIA expertise can be expected. The key strengths and challenges of training CIA with MYTILUS are discussed to point out focus points for how to make its approaches increasingly fit for participatory and decision-making processes in MSP to utilize its promising abilities for supporting ecosystem-based management.
An analytical framework is presented to describe the attenuation of regular and irregular waves propagating over floating seaweed farms. Kelp blades suspended on longlines are modelled, as a first approximation, as rigid bars rotating around their upper ends. Assuming small-amplitude blade motions under low to moderate sea conditions, the frequency-dependent transfer function of the rotations can be obtained, with quadratic drag loads linearized. Subsequently, the hydrodynamic problem with regular waves propagating over suspended seaweed canopies is formulated using the continuity equation and linearized momentum equations with additional source terms in the vegetation region. Analytical solutions are obtained for attenuated regular waves with their heights decaying exponentially as they propagate over the canopy. These solutions are utilized as the basis for predicting wave attenuation of irregular waves while stochastic linearization of the quadratic drag loads is employed. In contrast to energy-conservation-based models, which assume the velocity profile follows linear wave theory, the present solution can predict the reduced velocity inside the canopy. The analytical solutions are validated against experimental data and verified against a numerical flow solver. The model is capable of resolving the wave attenuation, along with velocity profiles and phase lag. Drag and inertial force exhibit cancellation effects on wave decay and both affect phase lag.