Recent presentations
Titles
Assessing net change of productive capacity: moving from
suitability to fish (slide-show,
5.0MB)
Efforts to achieve no net loss of productive capacity (PC) of fish habitat are
failing in Canada, and elsewhere. These growing losses, particularly in
freshwater, have a central role in ongoing global changes that threaten our
future. Canada has a large share of global freshwater resources and hence a
greater responsibility to help find solutions. For fish habitat, a
preoccupation with habitat suitability, and other indices of that ilk, have
diverted attention from self-sustaining fish populations, their productivity
and their fisheries. Symptoms of the problem are reviewed and a remedial
approach is offered alongside analogies from comparable conservation and
protection arenas such as fisheries, biodiversity, and human society. The
numerous symptoms include: net change (NC) of PC is primarily assessed by site
or project; PC is erroneously assumed to be a linear function of habitat
quality and supply; detection of NC at the site level is difficult and most
assessment programs are ineffective; management agencies tend to be
pre-occupied with few large projects although the aggregate impact of many
small projects is likely greater; cumulative impacts only gain cursory
attention; limited spatial and temporal attention spans result in an
ever-shifting baseline; folklore and anecdote are often more influential than
scientific evidence; many large-scale stressors causing net loss are ignored by
management agencies; mitigation and compensation efforts are often
species-directed rather than ecosystem-based. Current approaches to fish
habitat management are analogous to managing fisheries one fisher and one catch
at a time. The remedy has several key features: a total ecosystem approach is
required; all habitat changes need to be tracked within a spatial framework
specifying the total supply of PC; absolute development limits are necessary
across spatial scales as compensation has finite capacity to offset losses and
degradation; recognition that productive capacity: habitat quality-supply
linkages are inherently nonlinear with thresholds presaging profound
consequences; a much stricter legal framework with a reversed onus of proof to
protect ecosystems and ecosystem services; and, adoption of a rigorous adaptive
management approach. How implementation of this remedy is considered.
Assessing the likely impact of climate change on fish habitat
in Canada's lakes: a lake trout case study
(slide-show, 9.3MB)
This presentation provides an overview of the development and implementation of
CLAM, the Canadian Lakes Assessment Model. CLAM is an integrated regional model
for exploring the large-scale consequences of climate change and other
cumulative landscape changes for Canada's lakes and their fishery resources.
Ontario's freshwater ecosystems and climate change: impacts
and responses (slide-show,
2.3 MB)
This presentation provides an assessment of how Ontario's lakes and rivers and
their fishery resources will be affected by climate change later in the 21st
century.
The present status and future prospects of Canada's freshwater
ecosystems: battle between conservation and use
(slide-show, 6.4MB)
Canada is a country of many lakes (≈1.3 million) and rivers, with the largest
global share (≈30%) of freshwater ecosystems. Lakes >100 km2 number
over 550 and account for >40% of the global total. This abundance appears to
encourage profligate use of freshwaters. There are seven principal stressors:
nutrients, sediments, toxic chemicals, habitat loss and modification, exotics,
exploitation, and climate change. These stressors are relentlessly accumulating
as a function of Ehrlich’s equation: stress = population*activity*
technological intensity. The repeated pattern of land use development via
extraction and exploitation exemplifies a regime of rising stress. Stressors
often interact with negative consequences. Levels of some stressors like
nutrients and toxic chemicals have been partially managed while others like
climate change and exotics remain largely unchecked. Whilst existing
legislation would allow effective control of these stressors, governments have
largely abandoned efforts to regulate in favour of hoped-for side-benefits of
laissez-faire corporatism. Often governance is distributed to local or sectoral
interest groups without strategic oversight or recognition of science-based
sustainability limits. Much popular thinking today fails to recognize the
nested nature of ecosystems: economy is only possible within society and
environment, and society only within environment. Vital ecosystem services of
freshwaters are damaged in favour of exploitation of water as a commodity. The
future prospects for Canada’s freshwaters are dire as reactions to other
limitations, e.g., energy, collide with the impacts of current stressors. There
is much Canada’s scientist must do to help undo past mistakes and to improve
prospects for the future.
Tools for phosphorus management in the Bay of Quinte
(slide-show, 3.0MB)
Nutrient Budgets: The Bay of Quinte became highly eutrophic in the 1960s and
1970s. In the late 1970s a long-term program began to replace and upgrade
sewage treatment facilities releasing effluents directly into the bay. This
report describes the assembly and analysis of data for nutrient loads and
budgets for the Bay of Quinte covering the period 1972 to 2001. The methods
closely follow those used by Minns et al (1986b) in an earlier study of the Bay
covering the period 1965 to 1981. Changes in the frequency and spatial cover of
sampling made some simplifications of the methods necessary. Loads and budgets
were estimated by month and by bay section (upper, middle, and lower) for total
phosphorus (P), total nitrogen (N), and chloride (Cl). Point source loading of
P have declined dramatically with decreases continuing to the present. Point
source N loads are unchanged while Cl loads have increased. Analyses of whole
Bay and sectional budgets showed there have been shifts in retention and
estimated sediment P reflux in line with expectated declines in reflux after
point source load reductions were implemented. The colonization of dreissenid
mussels in the mid-1990s and the associated increases in macrophyte cover and
density have altered the nutrient budgets thereby increasing upper bay
concentrations. Recommendations for the future include more rigorous collection
of nutrient and flow data for the major rivers and point sources, allowing
refinement of certain components of the Bay of Quinte nutrient budgets. The
budget results provided a basis for development of a model simulating P
dynamics over the period 1972 to 2001 and predicting future conditions under
alternate hydrologic regimes, ecosystem conditions, and P management in the Bay
of Quinte.
Management Model: A simple input-output phosphorus model was developed and
implemented for the Bay of Quinte. The model was based on that described by
Minns (1986), whereby a three-section model of the bay was applied to the
upper, middle and lower Bay of Quinte. The model was implemented using STELLA
modelling software with a daily time step for the period 1972-2001. Hydrology,
stream concentrations, and sewage treatment plant (STP) flows and
concentrations were reproduced. Future scenarios cover the period 2002-2031.
Key parameter estimates can be changed to examine the effects of uncertainties
on model predictions. Simulation output includes daily values for all
compartments and major flows as well as annual and summer mean concentrations
by years in the water column and surface sediment compartments. The model
produced a high level of agreement with observations for the calibration
period. The future scenario results indicated the following: a) The recovery
process is expected to continue after 2001 as long as 2001 STP flows continue
at Certificate of Approval concentrations. Under these conditions, the water
concentrations will be, by 2031, close to steady state, within 0.2 μg L-1 of
their final value. b) With point source loading set at 2001 levels and zebra
mussel effects at median levels, the model predicts that under the low river
flow scenario (projected climate change effects), mean summer upper bay
phosphorus concentrations will increase by 9 to 13 μg L-1 above the baseline
scenario – a level well above the Remedial Action Plan target phosphorus
concentration for the upper bay. c) These results suggest that currently
approved final effluent concentrations will have to decrease at sewage
treatment plants discharging to the Bay of Quinte before flows from these
plants attain their rated capacities. An upper bay point-source loading limit
of 15 kg P day-1 will be necessary to safeguard water quality in the Bay of
Quinte for the long-term.