Potential Impacts on Biological Communities
A Contribution to the NSF FWI Changes, Attributions, and
Impacts Working Group (CAWG)
Lilian Alessa, University of Alaska Anchorage
Biological communities consist of any group of organisms occupying a niche in an ecosystem.
Thus, this includes human societies and their antecedent activities.
Individual Arenas of Potential Impacts
Please note that all the “arenas” below constitute a single, spatiotemporal cohesive continuum in
which water moves. Thus, changes in one arena will be linked or tightly coupled to changes in
another.
Rivers
Increased river flow may affect sediment and nutrients transport to nearshore areas thus affecting
habitat and breeding conditions particularly for anadromous fishes. Increased discharge as a
consequence of melting permafrost may be associated with accelerated transport of xenobiotic
materials thus affecting water quality for biota, including human consumption. Freshening of the
coastal shelves may affect organisms adapted for specific salinity parameters as well as optical
qualities of sea water which influence early development in many marine species. Travel via
rivers will be affected by increased or decreased flows depending on river hydraulics and
bathymetry. Water sources associated with ice free portions of river due to flow may also be
affected, in some cases, new opportunities may arise (see caveat on water quality) whereas in
others, freezing may occur due to low flow. The effects on fish populations are poorly
understood and river depth and water quality coupled with the seasonality of discharge and sea
ice comprise an area of concern. Timing of river freeze and thaw can affect the ability to harvest
fish and other biota in specific stages of their life histories (e.g., fish with optimal fat content,
etc.)
Permafrost
This area represents one of the more difficult challenges for modeling future potential impacts
with respect to spatial distribution and magnitude at fine scales. However, outcomes are roughly
binomial with increased permafrost melting potentially resulting in the loss of tundra ponds and
lakes as well as decreased ground stability affecting transportation and development by lowering
the integrity of the land surface. Permafrost changes in continuous versus discontinuous zones
appear to be different both in terms of rates and types of change. Depending on the rate of
change and the thickness of permafrost, soil moisture feedbacks may be strongly tied into
permafrost changes.
Thus, changes in vegetation and hence energy and nutrient budgets are expected to be tightly
linked. Such a system could alter feedbacks which result in accelerated energy and nutrient
fluxes creating well-established “core” and emerging “edge” effects. Changes in
vegetation/energy/nutrient feedbacks may facilitate changes in associated fauna from those
adapted to tundra/grasslands to those favouring shrub/treeline. These re-distributions of fauna
will affect the ability of arctic cultures to maintain recently familiar subsistence and agriculture
practices and force them to adopt strategies at which they are less efficient leading to nodes of
vulnerability at local scales. In addition, the migration of specific species, such as beaver, will
affect migration corridors for other species which periodically occupy the same niche (i.e.,
salmon). This type of feedback has the potential to cause regional-scale nodes of vulnerability
since anadromous fishes are also coupled to economic activities in the arctic.
Soil Moisture
Soil moisture has significant influences on microbial, nutrient and energy flows in the arctic
system. Moreover, it affects the time to which soils and surfaces are exposed to thawing, in part
owing to the high specific heat capacity of water. Coupled with changes in permafrost (see
above) and associated with changes in precipitation and albedo, soil moisture may drive the
composition and distribution of vegetation thus affecting evapotranspiration and soil drainage
feedbacks. In addition, these complex dynamics are affected by forest fire episodes, which are
linked to the overall water status of surface cover (i.e., vegetation). Forest fires and other
disturbances affect the insulation of permafrost by the organic layer and hence, sub-surface heat
flow potentially accelerating melting (see above). The mobilization of naturally occurring
organic materials may affect the quality of water entering rivers in watersheds as well as seepage
into groundwater. However, these impacts are poorly understood.
Sea Ice
The timing, thickness and patterns of break-up of sea ice have direct implications to a large range
of biota. Marine mammals which are dependent on sea ice, particularly polar bears and walrus,
are currently experiencing direct impacts such as isolation (e.g., polar bears stranded on fast
moving ice or conversely, on land), loss of access to prey species and changes in the location of
ice-associated phyto- and zoo-plankton. Sea ice provides access to human communities for
subsistence activities and unfamiliar patterns may render local knowledge unreliable under
conditions of rapid change. Sea ice is not used extensively for freshwater and is unlikely to be a
significant factor for terrestrial or near-shore freshwater budgets.
Atmosphere
Changes in the hydrological dynamics of permafrost and vegetation will result in changes in
rates and seasonality of water transport to the atmosphere via evapotranspiration. The effects of
this on local precipitation regimes is poorly understood and may be negligible. Changes in the
rates and/or patterns of precipitation may alter the fate of water that falls as snow and/or rain.
Humans “as” and “and” Biological Communities
The coupling of human communities with biophysical systems is termed the social-ecological
space which entrains multiple and complex feedbacks that consist of perception, action, response
and effect. Historically, settlement patterns in the arctic reflect a highly dynamic network
governed by resource acquisition where seasonality and kinship (i.e., ‘family land holdings and
subsistence rights”) played important roles in the location, frequencies and types of activities
(e.g., fishing, hunting, gathering, etc.).
With the advent of the conversion of many arctic peoples to Christianity, there followed a “new”
pattern of settlement whereby “villages” were built around church and affiliated schools. In this
century, members of Native communities have re-located to urban areas (e.g., Anchorage) in
addition to other rural villages. For example, the 1963 relocation of the village of Holikachuk to
the village of Grayling provides information on the integration of one rural community into
another rural community (Raymond-Yakoubian thesis 2001).
In some cases, natural disasters with flooding being the most common, has driven relocation
(e.g., Karluk, Allakaket and Alatna; Management and Planning Services 1978; Kelley Hegarty &
Associates 1995 a, b). In all three of these cases, the communities relocated to sites near to the
previous village site. Community planning reports identified steps needed to successfully move
the villages, and provided guidelines on how to assure long-term viability of the communities
(Management and Planning Services 1978; Kelley Hegarty & Associates 1995 a, b). Community
economic development, as well as potential energy sources and mining were part of these
reports, though access to freshwater appears to have been more of an assumption than part of the
planning. In modernity, traditional freshwater sites and their associated biota (esp. fish, greens
and berries) are still accessed via motorized vehicles (i.e., ATVs or snowmachines) but rarely on
foot. Figures 1a-d show the transition of dispersed settlements reflecting a more nomadic niche
to that (i.e., of permanent settlements) currently occupied.
Figures 1a-e. Location and type of communities on the Seward peninsula over a 200 yr period (a,
1800; b, 1850; c, 1900; d,1950; e, 2000). While migration has been toward the formation of
community “hubs”, there still exists a functional network that utilizes historic freshwater
resources. This network may be strongly linked to the formation and evolution of culture.
With respect to the focus of a potentially changing hydrological cycle in the arctic, such changes
in settlement patterns are significant because they alter several key variables which closely
interact with freshwater:
1. Reduced access to and greater dependence on single or singularly redundant sources of
FW for drinking, cleaning, subsistence and commercial uses. This includes reliance on
municipal infrastructure for water supply.
2. Changes in land use land cover change as a consequence of large-scale industrial
activities (i.e., mining and military uses).
3. Isolation of observations of change to a “sphere of influence” (the radius from the village
that residents travel to obtain freshwater and related resources) thus limiting the ability of
arctic residents to monitor change against oral histories thus limiting adaptive capacity.
4. Introduction of novel xenobiotics into freshwater sources at non-historic levels (e.g.,
mercury, arsenic, PCBs, etc.)
5. Changes in patterns of associated biota as arctic surfaces change (e.g., “green”) resulting
in losses of “familiar” resources (e.g., caribou) and gains of “unfamiliar” resources (e.g.,
beaver, moose).
6. Related to changes in patterns of freshwater-dependent biota are potentially major
impacts on fish populations, particularly anadromous and resident salmonid species.
These could arise as river flow changes alter water quality and quantities and impact
habitat and/or conditions which affect early development.
The impacts of changes in freshwater resources to biotic communities in arctic are highly
applicable to all human societies coping with changes in hydrological resources. Our research
shows that communities exist as networks consisting of agent types which lend greater or lesser
functionality in coping with change. SHOW/EXPLAIN NETWORK AND AGENT TYPES.
Figure 2. A simplified network showing the
relationship of communities and their water
sources.
Communities often have a single water source that
is most often used and, when queried, express
either no or a single alternative. This represents a
significant source of vulnerability since changes
in these sources may result in the emergence of
crisis, if rapid (i.e., ‘an emergency’) or the need to
fully re-structure of re-locate, if more slowly.
Freshwater is a relatively unique resource in that
most biota, especially humans, cannot continue physiological functions without it even over
short periods (hours to days). Moreover, changes in water quality can have rapid (within 1 to 2
generations) and, in some cases, acute effects on biological function (i.e., toxicity). Thus, agentbased models suggest that rapid changes in freshwater sources for human communities will
result in casualties (without emergency aid such as airlifted water from another source) or
migration (to the next nearest source). These outputs are shown in Figures 3a-b. It is important to
note that both scenarios require external resources to be applied to the affected community. The
implications to policy and fiscal infrastructure for both the resident and assisting communities
are significant and must be carefully considered as patterns in freshwater quantity, quality and
reliability change.
Figure 3a. Model output after 200 time steps (e.g. 200 days) showing a section of the network for
one community (ID 102), its associated water sources (IDs 129-131), and population graph for
this community. Alaskans migrate in as they discover an abundant water source. Figure 3b.
Model output from simulating reducing water source 129 to supporting 0 people, and water
source 130 to supporting only 25 people – the model predicts that the population drops and water
source 131 is maximized at 50 people. Alaskans migrate out, causing a potential cascade effect
on other communities.
A systematic and preliminary study was conducted in 2004-2005 to assess the “sociophysical
waterscape” in a portion of Alaska. These data are critical to understand how societies will
respond to changes by yielding insight into mechanisms. In addition, these data will enable nonlinear modeling of both sociocultural and biophysical variables simultaneously.
Individuals surveyed had a mean residence time of approximately 37 years in their community
and represented approximately 30% of the adult population with an equal ratio of males to
females in each age category. Perceptions regarding water quality, abundance, availability and
change were consistent among communities with approximately 85% of respondents perceiving
quality, abundance and availability to be high. Approximately 90% of respondents did not
perceive a change in water quality in inherent water sources while 62% perceived an
improvement in water quality from municipal sources. Highest values placed on water were
subsistence (83%), drinking (75%) and washing/cleaning (72%). Other values in decreasing
order of importance were travel (49%), commercial (24%), cultural activities (20%) and “other”
(13%). The majority of residents (87%) did not perceive any changes in the patterns or
abundance of freshwater sources. Most respondents (92%) had 1 or no other water source which
they would use if their existing source were unavailable. A majority of respondents listed
“contaminants” and/or “pollutants” (not associated with oral histories) as the primary area of
concern regarding freshwater resources (87%), this included inputs from sewage, fuel, landfills
and historic industrial activities such as mines and military sites. A smaller percent of
respondents queried the possibility of mercury deposition and acid rain as a consequence of long
range transport across the arctic (16%). Communities which expressed a perceived high capacity
to cope with change and had done so historically (within the residence time of the population
surveyed) had an approximately 3:1 ratio of  (“leader”) to  (“facilitator”) agents and a smaller
proportion of  agents (‘”wildcards” or “exploiters”). Community networks exhibited clear
clustering between  agents and external entities such as state and federal agencies, corporations
and businesses. Kinship ties were important for within-family exchanges but did not appear as
important with respect to overall community adaptive capacity.