Geoscience Reference
In-Depth Information
able future trends (over 20 years) in the production levels and/or production techniques for
those industrial sectors applying pressure on UK marine ecosystems also need to be em-
bedded in BAU projections.
The marine ecological coding of cumulative impacts on each habitat/service combin-
ation was conducted independently of the economic valuation. For both BAU and MCZ
designation, the coding of each cell contained three elements: (1) the percentage change in
provisioning between project inception (now) and the end of the study period (20 years);
(2) how quickly the ecological system would demonstrate this change in provisioning; and
(3) the trajectory of this change (i.e. linear, exponential, or log).
Figure 7.2
represents three trajectories for a change in provisioning in the service 'nu-
trient cycling', by way of an example of how the coding worked. There are two common
elements to each of the three trajectories: (1) compared with the level of nutrient cycling
providedbythehabitat at
t
=0,thereisa70%increase (i.e.0.7onthevertical axis);(2)this
change in provisioning takes 10 years, and after this point (from
t
= 10 to
t
= 20) the provi-
sioning of nutrient cycling by this habitat plateaus at +70% of current (
t
= 0) provisioning.
The three curves provide three alternative impact pathways from
t
= 0 to
t
= 10. In prac-
tice any one habitat would be coded with only one such trajectory. The highest point on the
vertical axis (in this case 0.7) provides the maximum expected annual benefit of the policy
versus BAU. In the coding applied in the MCZ case study (Hussain
et al
.,
2010
), 70% cor-
responds with a coding of 'high' impact, the mid-point of the range 50%-89%. Were the
coding to have been 'low' then the vertical axis would extend to 0.05, i.e. the mid-point
of 1%-9%. Further categories were 'very high' (90%-100%), 'medium' (10%-49%), and
'very low' (<1%).
