SOK Talks

Sources of Knowledge is not just about the annual forum. It has also been running a series of evening talks at the Park Visitor Centre auditorium. On March 13, 2019 at 7pm, Brian McHattie from Parks Canada will be giving a talk on: Iconic West Coast Orca Population in Crisis.

Fathom Five National Marine Park – Conservation Options

Fathom Five is a 114 km2 freshwater, protected area located on Lake Huron at the top of the Saugeen Peninsula. It was established as a provincial park in 1972 to protect sunken shipwrecks. Then in 1987, along with the regional islands of Georgian Bay Islands National Park (e.g., Flowerpot Is.), Fathom Five became the first site to be managed under the stewardship of Parks Canada’s national marine conservation area program.

The 2013 Sources of Knowledge Forum on “Changing Lakes” featured Scott Parker, a climate change ecologist with Parks Canada. Dr. Parker made the case for adopting a “resilience” approach to lake conservation as opposed to a traditional management approach.

Ecological resilience is the ability of an ecosystem to cope with disturbance and retain defining structures, functions and feedbacks. Whereas a traditional management approach may focus on resisting change, maintaining historic conditions or promoting system efficiency (e.g., maximum sustainable yield, single stable state), resilience prepares for disturbance by enhancing adaptive capacity and system diversity.

Today, Lake Huron is arguably a novel ecosystem, a system that no longer resembles its historic state in terms of composition and function. It’s a challenging context for conservation, and management approaches focused solely on maintaining or restoring the abundance of native species may simply be untenable. It is here that resilience creates space for discussing conservation goals based on ecosystem structure and function, and on disturbance and adaptive capacity.

In 2013, Dr. Parker found that much of the current change in the offshore ecosystem was coincident with the invasion of quagga and zebra mussels. This most recent disturbance followed an earlier invasion of sea lamprey and alewife and period of over-fishing which contributed to the near lake-wide extirpation of lake trout and loss of four of the six deepwater cisco species (two are extinct). The subsequent decline of the sea lamprey and alewife created favourable conditions for native lake trout and cisco to recover. However, their recovery was limited because the newly established mussels had played a role in making the lake less productive. Coincidently, one of the primary lake bed crustaceans, Diporeia spp (a tiny shrimp-like organism) a major food item for whitefish and other fishes, was experience a population collapsing. Together, these impacts contributed to a break in traditional transfer of energy and nutrients back into the water column. Thus, after the recovery from the sea lamprey and alewife invasion the lake, although resilient as shown by the return of the native species, did not return to its original state. Further, the subsequent dominance of invasive quagga and zebra mussels has virtually eliminated any prospect of restoring this ecosystem to its historical composition. It appears the offshore ecosystem of Fathom Five transitioned to a resilient although less-desired state.

As to the coastal areas there was, in 2013 a widespread concern with low lake levels, which by 2012 had approached twelve years of sustained low levels as compared with a maximum period of five years during the past century. Non-native species, including round goby, common carp, and Eurasian watermilfoil were present and had the potential to impact some coastal areas. In spite of this, in 2013 Dr. Parker felt that the coastal ecosystem of Fathom Five appeared to be in a resilient and desirable state.

There are a number of impediments to adopting a resilience approach to conservation. The relatively small size of Fathom Five (114 km2) and limited connectedness with other protected areas in Lake Huron makes aspects of resilience, such as protection of representative biodiversity and facilitation of disturbance recovery, more challenging. Secondly, governance of the lake is complex involving a multitude of organizations, stake-holders and rights-holders, such as Parks Canada and other federal department’s the Province, and the Saugeen Ojibway Nation.

In 2013, Dr. Parker felt that it was an opportune time for Fathom Five to consider incorporating resilience within its planning and management processes. Now, six years later, the topic of this years’ SOKF is intended to focus on whether the expectations for Fathom Five have been met and what should be its future. Accordingly, Dr. Parker’s 2013 observations and prescriptions for the lake are relevant. At the Forum on May 3 to 5 of this year, Dr. Parker, together with Cavan Harpur, Parks Canada Ecologist will be offering an update of resilience in their presentation entitled: But Doth Suffer a Sea Change, Into Something Rich and Strange: An Update on the State of the Fathom Five Ecosystem

Great Lake Water Levels – The Long View

The Sources of Knowledge Forum (SOKF), a charitable non-profit organization based in Tobermory, was founded to inform local people and a wider general public about the unique environment that is the Saugeen Peninsula and its surrounding lake. SOKF hosts an annual, three day public seminar in Tobermory to highlight some aspect of this environment. SOKF also has a responsibility to extend its reach and to develop a model for a larger knowledge network. With that in mind SOKF is starting a monthly blog to highlight current issues and resurrect topics from previous forums which are relevant today.

The next annual forum, on May 3 to 5, 2019, will focus on Fathom Five National Marine Park. Ten years ago, as part of the first forum, Steve Blasco of the Geological Survey of Canada, gave an overview of the history of Lake Huron since the end of the last ice age 12,000 years ago. Over that period the lake levels have changed dramatically. There have been at least three extremely low water level episodes and three high ones. 4500 years ago, the Peninsula, including the cliffs along the Georgian Bay shore, was almost submerged.

Between 10,000 to 7,500 years ago the lake levels were generally low and forests grew on what are now the lake beds of Lake Huron and Georgian Bay. Today the remains of those forest are known as the “drowned forest’ because the trunks are still rooted on the land where they originally grew. Those dramatic changes in lake levels, varying by as much as 125 meters, were caused by the receding glaciers of the last ice age, which allowed the land, freed of the weight of the ice, to spring upwards. Climate changes also played a role as did the way the lakes drained into the sea. Originally, the Mississippi was the preferred route to the sea. Ten thousand years ago the lakes drained through the Pettawawa/Ottawa rivers into the St. Lawrence.

Today’s modest changes in the lake levels (as much as two meters) have two principal causes, precipitation (including run off) and evaporation and these are the result of weather. Water levels rise and fall in seasonal cycles, with annual highs typically occurring in the summer and annual low levels in winter. Water levels also fluctuate in longer cycles in response to persistent wet or dry conditions that may last for a number of years. Declining annual ice cover and warmer water temperatures increase the potential for evaporation when water is open and there is a large difference between air and water temperatures. A mild winter produces less evaporation.

Inevitably, humanity has an impact on lake levels, although they are much less than is often believed. Since the late 19th century, Lake Michigan-Huron has been lowered by about 16 inches due to dredging and other channel changes in the St. Clair and Detroit Rivers. The International Joint Commission (IJC), which manages the Great Lakes on behalf of Canada and the US, published a study in 2012, which found that erosion since 1962 had caused another 3 to 5 inches of lowering. However, the erosion is not ongoing. The effect of the diversion at Chicago has removed the equivalent of lowering the Lake Michigan-Huron by about 2 inches whereas the Long Lac and Ogoki diversions into Lake Superior have raised Lake Michigan-Huron by the equivalent of 4 inches..  The table below illustrates humanity’s impact.

Human Impacts on Lake Levels

                                                        Long Lac 
and Ogoki
Chicago WellandNet Effect
+ 0.06 m

– 0.02 m

– 0.02 m

+ 0.02 m
Michigan / Huron
+ 0.11 m

– 0.06 m

– 0.06 m

– 0.01 m
+ 0.08 m

– 0.04 m

– 0.13 m

– 0.09 m
+ 0.07 m

– 0.03 m


+ 0.04 m

  International Joint Commission

Because of climate change, the IJC admitted that there is considerable uncertainty regarding future trends in Great Lakes water levels. In short, the 2012 IJC study indicates that over the next 30 years, lakes Superior, Michigan, Huron and Erie levels are likely to go down – but they may go up.

You can find the full, 236 page report at