CASE STUDIES: STEP 5 DERIVING SPECIFIC PROTECTION GOALS
In this section, the derivation and description of SPGs for selected ecosystem services is presented based on the combined outcome for case studies in step 4 (Table 5.5). The ecosystem services selected to illustrate the approach represent those considered to be of potentially high concern (relatively more habitat x ecosystem service cells prioritised as high or medium concern of chemical impact) and include food provisioning, genetic resources, natural hazard regulation, water purification / soil remediation / waste treatment, recreation and ecotourism and nutrient cycling.
The order of the columns in Table 6 was changed from the original table proposed by EFSA (2010), in order to describe chronologically the derivation of SPGs for SPUs, prioritised in previous steps for each chemical case study (Section 4). Nevertheless SPGs are ultimately framed in five dimensions according to EFSA’s guidance: ecological entity (individuals, (meta)populations, functional groups); attributes (process / behaviour, abundance / biomass); magnitude of impact; temporal and spatial scale of impact. The degree of certainty that the specified level of impact will not be exceeded was not addressed. The final column ‘legal requirement’ in Table 6 provides a reference against which the SPGs derived by using the EFSA framework can be checked. NB the listed legal requirements relate to the SPUs specified in each row.
The Task Force concluded that more ecological knowledge is required to define the maximum magnitude of impact that would still enable the sustainable delivery of an ecosystem service by an SPU. There is a need to define acceptable / sustainable levels of impact more explicitly than currently defined in EFSA’s guidance (EFSA, 2010) and in environmental regulations (Section 3). There is some existing guidance for defining spatio-temporal scales of impact, for example in EFSA’s aquatic ERA guidance document (EFSA, 2013). EFSA adopts two approaches: ‘ecological threshold option’ and the ‘ecological recovery option’. The ecological threshold option focuses on the identifying the maximum tolerable impact on the entity/attribute of concern in order to protect the ecosystem service of interest. The scientific challenge here is to have sufficient knowledge to be able to link ecological changes to changes in ecosystem service delivery (i.e. ecological production functions) and to identify thresholds of ecological change at which ecosystem service delivery is affected. Given the uncertainties associated with identifying thresholds, a precautionary approach is to assume that ‘maximum tolerable impact’ is ‘no/negligible impact’.
The recovery option considers some impacts at limited spatial and temporal scales to be acceptable assuming that full recovery occurs. The scientific challenge here, in addition to establishing ecological production functions, is understanding recovery processes within a landscape context and the spatio-temporal dynamics of ecosystem service delivery.
In addition, there are the risk managers to consider, who may, for non-scientific reasons, find certain risks acceptable or not acceptable. Examples here may be the focus on the individual-level for vertebrates and the more stringent controls on effects for GMOs.
The Task Force considered that the magnitude of an acceptable impact will differ between SPUs and would depend upon factors such as natural variation or fluctuations, which could be determined from retrospective analysis of control or reference data. The Task Force also suggested higher magnitudes of effect might be tolerable / sustainable for shorter periods and/or smaller areas of exposure according to the principle that all three dimensions of impact scale are inter-linked (EFSA, 2010; EFSA, 2013), but their relation to real world tolerance has yet to be proven.
As stated above, the magnitude and scale of acceptable impacts need to be defined by risk managers based on underpinning science, together with other considerations. One important consideration being that an acceptable impact needs to be measurable, to ensure protection goals are met. For illustrative purposes, an example of how this might be done is given in Table 6.1 and followed throughout Tables 6.2 – 6.7. The spatial scales of impact used are considered suitable for application at three different scales: i) local impacts within 0.1 km of the source / site of exposure, e.g. field margins, edge of field ditches, shore line, river mixing zones; ii) landscape impacts up to 1 km e.g. agricultural, urban or natural and iii) regional scale impacts ranging over distances exceeding 1 km. A linear measure is applied for each SPU/habitat combination which can represent a measure of length, e.g. in the case of flowing water bodies, or of area (as a measure of the radius from the central point of exposure), e.g. for static water bodies and terrestrial habitats. In both cases these metrics are intended to be indicative of scale and require case by case evaluation when used in the derivation of specific protection goals.
The following definitions of ‘sustainable’ levels of impact are based on the premise that effects would be unsustainable if any one of the three dimensions of effect are exceeded. As stated above these proposals are for illustrative purposes only. They are offered as a means of stimulating debate that requires both scientific underpinning and risk manager involvement to agree actual definitions.
Table 6.1: Potential definitions of sustainable (acceptable) impacts
Rules of thumb for designating spatial scale of impact:
- If legal requirement includes EC Regulation 1107/2009 – consider field to edge of field (at least initially).
- If legal requirement includes Habitats Directive – consider specific ‘interest feature’ protected under the Directive.
- If legal requirement includes WFD – consider water body level.
- If ecosystem service is a cultural service – consider landscape or water body level.
Rules of thumb for designating temporal scale of impact:
- If ecosystem service is a cultural service – consider weeks to months (visible growing seasonal).
- If ecosystem service is a supporting service – consider all year round importance and how temporal scale is applicable.
- If attribute includes taxonomic richness or genetic diversity – consider all year round importance, therefore temporal scale may not be applicable, unless some contributing species are migratory.
Table 6.2: Ecosystem Service – Food provisioning
Table 6.3: Ecosystem Service – Genetic resources
Table 6.4: Ecosystem Service – Natural hazard regulation
Table 6.5: Ecosystem Service – Water purification / soil remediation / waste treatment
Table 6.6: Ecosystem Service – Nutrient cycling
Table 6.7: Ecosystem Service – Recreation and eco-tourism