to continued shoreline development, increased runoff,
subtle sub-lethal effects that are insidious and difficult to
increased air pollution from increased vehicle distance
assess. For example, many compounds can impair or
traveled, energy demands, etc., and increased loss of fish
disrupt the endocrine system, interfering with proper
and wildlife habitat including wetlands.
development, reproduction and growth of certain species.
Even more disconcerting is that fact that many of these
These future challenges are summarized below in terms of
effects do not exhibit a linear dose-response, so that
findings, which reflect important insights and discussion,
declining concentrations of current chemicals may not
and recommendations, which reflect specific initiatives and
always result in a decline of adverse effects. On the
5.2
approaches.
contrary, what is observed in some cases is the emergence
of a new endpoint that was masked by a more evident effect
caused by higher concentrations.
5.2.4
Findings
Inputs of nitrogen and phosphorus from point sources
Long-term objectives for recovery are necessary to achieve
have been regulated for decades, but the loadings of
future progress in restoring and maintaining the chemical,
nutrients from nonpoint sources still results in excess
physical and biological integrity of the waters of the Great
ambient water concentrations. Major sources of these
Lakes basin ecosystem. The Great Lakes Water Quality
nonpoint inputs are agricultural operations, both crop-
Agreement should be reexamined in light of these objec-
based and animal-based. Runoff and animal manure
tives.  The reestablishment of some native species could be
disposal and treatment are not well regulated or controlled.
one such objective - recognizing that many native species
In addition, nutrient cycling is not fully understood, as
will have to be introduced and that restoring the Great
evidenced by the recent hypoxia trends in the Lake Erie
Lakes to an historical natural ecosystem will not be
central basin.
possible.
The majority of scientific opinion supports the concern that
Institutional effectiveness is impeded by a multitude of
anthropogenic-induced climate change is affecting chemi-
agencies and organizations fulfilling their own objectives
cal, biological and physical aspects of the Great Lakes.
with insufficient coordination, in the absence of shared
Future effects that have been identified include the impact
long-term goals and strategies, and according to disparate
on lake levels. Another significant effect will be the impact
visions.
of warming on biological community structure.  Changes in
either fish predator species or algal assemblages will further
A renewed sense of shared purpose is needed that delin-
impact other trophic levels through top-down and bottom-
eates the image of the basin as a total system, that people
up effects. Finally, warming of the Great Lakes will result in
accept collectively, and that has personal relevancy. No one
greater evaporation of semi-volatile compounds from the
vision of the Great Lakes may be attainable, or practical,
water column, which will accelerate the rate of leaching
because of the importance of this vast resource among
from sediment reservoirs to the water column.
many users.  The challenge for the future will be to develop
a process, or a forum, where shared values can be dis-
The control of exotic species that have been introduced to
cussed, and decisions made to protect and maintain the
the Great Lakes ecosystem have been and will continue to
high natural amenities that sustain the use and enjoyment
be a major challenge for resource managers and for Great
of the resource. If expressed as a key question, it is “how do
Lakes communities. The current efforts to prevent further
we organize ourselves to deliver an ecosystem approach?”
introductions have not been effective, however, as the
current rate of new introductions is about two species per
Greater integration is needed to address the tendency of
year.
the current practice of science and policy to be over-
compartmentalized, with policy frequently lagging behind
Exotic species introductions often lead to changes in the
current scientific understanding.  The goals and purpose of
biological community structure, and changes within the
the Great Lakes Water Quality Agreement cannot be
entire food web. These changes can cause instability in the
achieved until greater integration occurs, for example, in
overall ecosystem.  Some changes have no clearly under-
relation to policy decisions that affect the interface of land
stood cause, such as the decline of Diporeia in all of the
and water, or in the case of the environment and the
Great Lakes, with the exception of Lake Superior.  Such
economy.
stresses are anticipated in the future and may be due to
combinations of stressors.
Additional formal binational programs are necessary to
contribute greater inter-operability to the institutional
Finally, the impact of future increases in population and the
framework, building on examples such as International Air
growth of urban areas within the basin will inevitably lead
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