In addition to reporting individual drivers of change, it was critical for VECTORS to consider interactions between multiple users and sectors and possible conflicts in terms of resource exploitation from different sectors, with specific reference to the VECTORS target areas of concern; outbreaks, invasive species, and changes in species distribution and productivity.
The nature of interactions can be considered as follows:
Neutral: Factor 1 has no effect on Factor 2
Additive: The effects of Factor 1 and Factor 2 are additive
Synergistic: The combined effect of Factor 1 and Factor 2 exceeds the sum of their additive individual effects
Interference: The combined effect of Factor 1 and Factor 2 is less than the sum of their individual effects
Figure 1: Possible interactions between pressures for the North Sea system. These are subjective expert assessments which are “average” effects and do not preclude specific interactions that vary from the suggested model. The colour indicates the nature of the interaction (Neutral, Additive, Synergistic, or Interference) but there is no indication of the effect being “good” (wind farms in association with protected areas) or “bad” (litter impacting on tourism). This is case dependant.
These interactions can lead to constraints and enhancements in the development of single sectors and will influence the net pressures on the VECTORS areas of concern. In predictive terms, the first two responses are easier to deal with, while the latter two are more conceptually awkward. However, this classification of interactions does not imply either beneficial or damaging overall effects, for example some enhancements (additive or synergistic) might be considered “a good thing” (i.e. increased primary productivity). The consequences of most interactions will depend on local context and thus the nature, scale and dynamics of the habitat must also be considered. Conceptually, this is moving towards “the ecosystem approach” as advocated in the Millennium Ecosystem Assessment. These context-dependant interactions represent a particular difficulty in terms of transferring the scientific knowledge into policy mechanisms1.
The VECTORS deliverable D1.22 begins with a subjective assessment of the interactions (Fig. 1) and briefly describes the most important uses of the marine environment and their interactions, as well as the existing and the potentially arising conflicts in the VECTORS European regional seas.