Plastic Waste

On March 10 this year the Province of Ontario announced that it was considering a ban on plastic waste as part of a broader strategy to send less waste to landfill sites. Almost one tonne of waste per person is generated annually in Ontario and only 30 per cent is diverted from landfills by composting and recycling. According to the government this rate of diversion has not changed over the last thirty years. The Environment Minister Rod Phillips has said, “Plastics is a priority from our government’s point of view, particularly as we talk about plastics in our waterways.” The government estimates that almost 10,000 tonnes of plastic debris enter the Great Lakes each year.

In a February 2017 report by the International Joint Commission (IJC), the Canada/USA body that manages the lakes, studies have documented the occurrence of plastic debris, including plastic bags, bottles, boxes, fibres, micro-beads, and cigarette butts, in marine and fresh waters including the Great Lakes. Larger plastic debris degrades into smaller micro-plastics, and it is these smaller particles that are of particular concern. Micro-plastics generally refer to particles 5 mm or less in size and include; micro-beads from personal care products; fibres from synthetic clothing; pre-production pellets and powders; as well as degraded pieces from larger plastic products. Little is known about the fate of these smaller plastic particles and the IJC is concerned about their potential impacts on environmental and human health.

Plastic enters the Great Lakes in many ways. Most egregiously, people on the shore and on boats throw litter in the water but micro-plastic pollution also comes from wastewater treatment plants, storm water and agricultural runoff. Some plastic fibres become airborne, possibly from clothing or building materials weathering outdoors and these are probably deposited into the lakes directly from the air.

The IJC made 10 recommendations, one of which was to develop a model to determine the sources and fate of micro-plastics. In their Aug 20 2018 issue, The Conversation, an independent, not-for-profit media outlet, reported on the work of two scientists, from the Rochester Institute of Technology, Matthew J. Hoffman and Christy Tyler, who have developed a computer model to track the movement of micro-plastics in the lakes.

They found that, while plastics often accumulate in large floating garbage patches in the oceans, in the Great Lakes there may be temporary accumulation patches but they do not persist as they do in the ocean. In Lake Erie and the other Great Lakes, strong winds break up the accumulated patches and there was no evidence for a Great Lakes garbage patch. This appears to be good news except that we know that a lot of plastic is entering the lakes so if it is not accumulating in large patches, where is it?

Hoffman and Tyler’s computer model shows that most of it ends up closer to shore (see map below.) This helps to explain why so much plastic is found on Great Lakes beaches. In 2017 alone, one group of volunteers collected more than 16 tons of plastic at beach cleanups. Thus, the plastic is ending up near shore, where more wildlife is located and where we obtain our drinking water.


Average density of simulated particles in the Great Lakes from 2009-2014. Notice that there are no patches in the middle of the Lakes, but more of the particles are concentrated near the shores. Credit: Matthew HoffmanCC BY-NC-ND

The scientists estimate that over four tons of micro-plastic are floating in Lake Erie. This figure is only a small fraction of the approximately 2,500 tons of plastic that they estimate enters the Lake each year. According to their initial simulations, much of the plastic is expected to sink. This prediction is supported by sediment samples collected from the bottom of the Great Lakes, which can contain high concentrations of plastic. You can see the computer simulation of the dispersal of micro-plastics in Lake Erie here.

Another IJC recommendation was to assess the potential ecological and human health impacts of micro-plastics in the Great Lakes. One such recent study – available here.

The researchers found micro-plastic particles – fragments measuring less then five millimetres – in tap water and beer brewed with water from the Great Lakes. Since many studies indicate risks to human health when plastic particles such as synthetic polymers are ingested, clearly more needs to be known about the presence and abundance of micro-plastic particles in human foods and beverages. The PLOS study investigated the presence of micro-plastic particles in 159 samples of globally sourced tap water, 12 brands of Great Lakes beer, and 12 brands of commercial sea salt. Of the tap water samples analyzed, 81% were found to contain micro-plastic particles. The majority of these particles were fibres (98.3%) between 0.1–5 mm in length and there was an average of 5.45 particles per litre. Plastic debris was also found in each brand of beer and salt. Of the extracted particles, over 99% were fibres. The average number of particles found in beer was 4.05 particles per litre and the average number of particles found in each brand of salt was 212 particles per kg. Based on consumer guidelines, the study indicated that the average person ingests over 5,800 particles of synthetic debris from these three sources annually, with the largest contribution coming from tap water (88%).

The IJC also recognized that it is vital to change peoples’ behaviour and the only way to do that is through education. They recommended that Canada and the USA increase their funding of education programs, particularly for grades K to 12.

Tobermory Seiches

A Review of a study by John Greenhouse

A seiche (SAYSH) is a wave in an enclosed or partially enclosed body of water. Like water in a jostled tub, energy sloshes back and forth between the boundaries of the water body creating what are known as “standing waves”, not unlike those that can be seen in a skipping rope. Seiches and seiche-related phenomena can be observed on lakes, reservoirs, bays, harbours and oceans. Some can be very dramatic, but others are all but imperceptible.

On the Great Lakes a seiche derives its energy (the “jostling”) from the atmosphere. A sharp change in pressure or wind speed will produce a wave in the body of water (Figure 1). The wave is reflected repeatedly from the shores, generating standing waves with one or more peaks. The repetition time, or “period” of the oscillation is determined by the size and shape of the water body, and by its depth.  In large water bodies the period of oscillation will be several hours. As shown in Figure 1, the thermocline can also oscillate as a standing wave.

Figure 1. Wind generating standing waves on the surface and the thermocline of a lake.
Frankemann [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)%5D

In bays leading off Lake Huron the water level will rise and fall with the lake, but they also have oscillations with periods determined by the size, shape and depth of the bay itself. These harbour oscillations or seiches, have periods typically from a few minutes to an hour.

Large seiches occur every few years and, are exceptional events. They are generated by extreme weather out in the big lake and, when they arrive at a harbour, they can be hugely amplified. They are extreme events but a seiche is continual. The lake and its harbours are in almost constant but very low level oscillation because the atmosphere itself is never completely static. This continual seiche activity is most often imperceptible to observers on land or in boats due to the extremely long period and low amplitude of the wave.

John Greenhouse is fascinated by these harbour oscillations. They have already been studied quite extensively but there are nothing more than anecdotal accounts of the seiche activity in individual bays and harbours around the peninsula. Do they have characteristic and repeatable periods independent of the those in Lake Huron itself? Are these characteristics explainable in terms of the size, shape and depth of bays? Do these characteristics determine what happens when a major seiche comes from the big lake outside? Despite an extensive body of literature on the subject, there seemed to be a local knowledge gap to fill.

Figure 2. Numbered red dots indicate the location of measuring stations in this study.

Accordingly, over a four year period, John Greenhouse set up water-level monitoring stations (Figure 2) at 19 locations in Tobermory and along the western shore of the peninsula.

The frequency of a wave is the number of times per second that the wave cycles. Frequency is measured in cycles per hour (cph). The period of the wave is the time between wave crests. The period is also measured in time units. The period and frequency are inverse of each other. Frequency, the inverse of period, is measured in cycles per hour (for example, 4 cycles per hour implies a period of 15 minutes).

John has characterized each harbour in terms of the frequency of its oscillations. He found that each harbour had its own characteristic frequency that was consistent over time and it was unique to that harbour. In other words, each harbour or bay had its own “signature”. 

The dominant frequency of the harbours he studied ranged from 0.8 cph at Stokes Bay (period of 75 minutes) to 13 cph (period of 4.5 minutes) at Little Tub Harbour.  These harbour frequencies are broadly consistent with predictions based on the size, shape and depth. They are quite distinct from oscillations in the big lake, which also can be measured in the harbours but have much longer periods.

As noted above, a large seiche coming in from the lake can hugely amplify a seiche in a harbour like Little Tub with possibly damaging effects. The next step in this study may be to obtain simultaneous measurements of a large seiche on the lake before it reaches the harbour and measure the harbour’s response. From that one might be able to predict a large seiche and mitigate the effects on property.

The full paper will soon be published on the SOK website (www.sourcesof knowledge.ca). In the meantime you might enjoy reading Chapter 7 of Sherwood Fox’s book, The Bruce Beckons, who gives a wonderful description of  a very large seiche in Stokes Bay in the late 1940’s.

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
Superior
+ 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
Erie
+ 0.08 m

– 0.04 m

– 0.13 m

– 0.09 m
Ontario
+ 0.07 m

– 0.03 m

   negligible

+ 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 https://www.watershedcouncil.org/uploads/7/2/5/1/7251350/document_3_lake_superior_regulation_full_report.pdf.