A new perspective on changing Arctic marine ecosystems: panarchy adaptive cycles in pan-Arctic spatial and temporal scales - Ocean Sustainability in the 21st Century - page 177

5.3 Ecosystem resilience and reorganization
In general terms, an ecosystem may be considered resilient if the basic functional relation-
ships across spatial and temporal scales remain relatively intact when exposed to perturba-
tion. Systems with high species diversity generally have more functional redundancy, thus
further increasing resilience. Large-scale physical conditions provide the basic habitat char-
acteristics and nutrient availability to support reasonably consistent patterns of microbial
and planktonic productivity at the small scale (Domain 4). This productivity, in turn, pro-
duces food that can be concentrated by physical processes in hot spots where predators feed
(Domain 3), which in turn drives migration and aggregation patterns of species at the higher
trophic levels, characteristic of Domain 2. As long as planktonic reorganization still results
in the provision of sufficient quantity and quality of food, the rest of the food web will not
be greatly affected by reorganization in Domain 4.
When the reorganization within one spatio-temporal domain begins to affect the basic
structure and function of other domains, however, then the ecosystem is susceptible to an
overall reorganization, perhaps resulting in a new steady state with different characterist-
ics of production, diversity, function, distribution, and abundance of organisms (Ω phase of
panarchy). In the Arctic Ocean, where we currently have a fairly simple marine ecosystem
with biomass dominated by a small number of species, we appear to be at the beginning of
just such a process. The large-scale loss (Domain 1) of sea ice is resulting in a new nano-
planktoncommunity(Domain4)inmanyareas,dominatedbyspeciesanorderofmagnitude
smaller than some of their predecessors that were significant for primary production, e.g. di-
atoms and dinoflagellates (Li et al ., 2009 ; Coupel et al ., 2012 ) . The smaller phytoplankton
species are more efficiently grazed by other organisms in the microbial food web, resulting
in less energy transported to higher trophic levels (Domain 4 to Domain 3) (cf. Parsons and
Lalli, 2002 ) , and thus potentially less prey available for predators, including human hunters
and fishermen. The biomass removal in commercial fisheries is very low, however: only
about 0.2% of the harvestable production in the Barents Sea is channelled through the cod