The Davis Strait - DCE - Nationalt Center for Miljø og Energi

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temporary and dynamic like the marginal ice zone and polynyas) and processes
such as the spring bloom in primary production.
The potential impact on VECs of activities during the various phases of the
life cycle of a hydrocarbon licence area are summarised in a series of tables
in chapters 10 and 11. The tables are based on a worst-case scenario for impacts,
under the assumption that current (2011) guidelines for the various
activities, as described in the text, are applied. For each VEC, examples are
given of typical vulnerable organisms (species or larger groups) in relation
to specific activities. These examples are non-exhaustive.
Potential impacts are assessed under three headings: displacement, sublethal
effects, and direct mortality. Displacement indicates spatial movement of animals
away from an impact, and is classified as none, short term, long term
or permanent. For sessile or planktonic organisms, displacement is not relevant,
and this is indicated with a dash (-). Sublethal effects include all notable
fitness-related impacts, except those that cause immediate mortality of
adult individuals. This category therefore includes impacts which decrease
fertility or cause mortality of juvenile life stages. Sublethal effects and direct
mortality are classified as none, insignificant, minor, moderate or major.
Dashes (-) are used when it is not relevant to discuss the described effect (if
no members of a VEC are vulnerable to a given activity).
The scale of potential impact is assessed as local, regional or global. Impacts
may be on a higher scale than local if the activity is widespread, if it impacts
populations originating from a larger area (e.g. migratory birds), or if it impacts
a large part of a regional population (e.g. a large seabird colony).
Global impacts are those which potentially affect a large part of (or the entire)
world population of one or more species.
It should be emphasised that quantification of the impacts on ecosystem
components is difficult and in many cases impossible. The spatial overlap of
the expected activities can only be assessed to a limited degree, as only the
initial oil activities are known at this point. Furthermore, the physical properties
of potentially spilled oil are similary not known. Moreover, there is
still a lack of knowledge concerning important ecosystem components and
how they interact. In addition, ecosystem function will potentially be altered
in the near future due to climate change.
Relevant research on toxicology, ecotoxicology and sensitivity to disturbance
has been used, and conclusions from various sources – the Arctic Council
Oil and Gas Assessment (Skjoldal et al. 2007), the extensive literature from
the Exxon Valdez oil spill in Alaska in 1989, as well as the Norwegian EIA of
hydrocarbon activities in the Lofoten-Barents Sea (Anon 2003b) have been
drawn upon.
Many uncertainties still remain and expert judgement or general conclusions
from research and EIAs carried out in other sub-Arctic or Arctic areas have
been applied in order to evaluate risks and to assess the impacts. Much uncertainty
in the assessment is inevitable and is conveyed with phrases such
as ‘most likely’ or ‘most probably’.