Is Biodiversity in the Bay of Fundy Threatened by Tidal Energy?

Due to the irrefutable rise in greenhouse gases, it has become necessary to develop sustainable and renewable sources of energy. Naturally, in searching for such a source, scientists and engineers have turned to one of the Earth’s most abundant resources, the ocean. Companies are now investing in marine renewable energy installations (MREI) such as wind turbines and tidal energy. Locally, this has manifested in the form of the tidal energy installation in the Bay of Fundy’s Minas Passage. It is important to note that while there are definite benefits to tidal energy, there will undoubtedly be negative effects those of which will primarily affect the Bay of Fundy. The positive repercussions of tidal energy should have both a local and far reaching impact. The negative aspects of this project will be strongly felt in the Bay of Fundy and surrounding areas.

Context:

According to Force,  Canada’s leading test center for in stream tidal energy technology, the Bay of Fundy “pushes about 160 billion tonnes of water every tide- more than all the fresh water rivers and streams combined.” There is, undeniably, an incredible amount of force contained within the tides of the Bay of Fundy. However, analyzing the outcomes of a tidal energy installation requires a holistic perspective of the situation at hand, a perspective that is not entirely utilitarian or anthropocentric. After all, it is mankind’s notorious anthropocentrism that has caused the decimation of many of Earth’s natural resources. There is no doubting that the Bay of Fundy is an immensely powerful, oceanic system. Its tides are said to be over 16 metres, with the horizontal range being as much as 5 kilometers.  As well, the tides in the Bay are remarkably fast, reaching 10 knots at peak surface speed. Tidal energy, in many ways, reflects the tides themselves, as tidal energy feeds off that of the ocean currents, as well as the reliability of the tides themselves.

It is estimated that there are more than 7000 megawatts of potential power in the minas passage. With Nova Scotians creating more pollution than they can handle, it is no wonder that we are looking for a cleaner source of energy.  Renewable energy is a necessary condition for a healthy future. Yet, the fact cannot be neglected that for many who live near it, the Bay of Fundy contains certain livelihood and recreation. This is not to mention the many organisms that live below the surface of the water, in the depths of the bay. Theirs is a complex ecosystem to which most are ignorant of. This ecosystem is comprised of marine, benthic and pelagic communities, as well as fish, to name a few. All of these communities affect each other, just as they affect surrounding societies that rely on them for their livelihoods. It would be utterly negligent for humans to neglect the complex inter-workings present beneath the surface of the Bay of Fundy.

 Habitat loss:

It is estimated that, in general, the greatest habitat loss could occur during the construction and decommission of the turbines. This is unavoidable. However, once constructed, the installation itself may serve as a sort of artificial habitat for marine organisms. Though there still needs to be prolonged research on the issue, it is known that throughout the year, there is barely a time when fish are not moving through the tidal energy site. Nearly 30 different species of fish use the Minas Passage at some point. It is thought that the American Shad could possibly be affected the most, as they pass back and forth through the Minas Passage in order to mate.

Collision/ Entanglement:                

Turbines have a very real capability to kill marine organisms. This can happen several ways. For instance, marine organism would be attracted to underwater light that the installation would exude, thereby placing them in harm’s way. Fish and other creatures that travel in groups are far more likely to be affected by the turbines.

photo courtesy of: Wikimedia commons

 Velocity Change:

In addition to the other detriments that tidal energy could cause to the marine ecosystem is the problem of changing underwater current velocity. This could prove to be detrimental in that it would change the rates of sediment suspension and deposition, as well as affect the settlement of marine larvae. This could diminish the food supply brought to benthic filler feeders. It can decrease upwelling (the process that mixes nutrient rich waters from the bottom), influence primary production, and /or have indirect effects on fish and birds that feed on the benthic community. It is estimated that, although a small scale tidal energy installation is not likely to produce quantifiable, negative side effects, any large scale commercial operation would be liable to “produce unacceptable changes in the ecosystem.” According to a report concluded by the Offshore Energy Research Group, “At present there is a great deal of uncertainty about what level of energy reduction is likely to be acceptable.”

Electrical Fields:

Unfortunately, there is little known about the cumulative effects that electrical fields around subsurface cables will have. It is thought these cables might affect ground fish and mobile invertebrates, such as lobsters. The impact that these changes could have on the oceanic ecosystem, as well as that above the water,  is unclear as yet. As well, Demersal fish such as winter flounder and Atlantic sturgeon could be especially susceptible to effects imposed by intrusive electrical fields.

Marine Organisms Affected:

As mentioned earlier, the construction of a tidal energy turbine in the Minas Passage would likely have a negative impact on fisheries. Many different types of fish will be affected.  For instance, they could become confused during the construction process, as noise and vibrations echo through the water. This could permanently damage the sensory perceptions of the fish, ultimately changing their behaviour. It is possible that, even after the turbines are constructed, their operation could affect the sensory perceptions of some fish. Perhaps most worrisome for fishermen in surrounding areas is the effect that the tidal installation might have on the lobster industry. Within the Minas Passage area, lobster fishing is the most valuable, with an estimated revenue as high as $2.5 million in 2002. Due to the tidal energy project, the lobsters face habitat loss as well as changes in migration patters. For the fishermen, the area where they fish may have to change altogether.

Lobsters are not the only commercial fishery that could be affected by the tidal energy project. Within the Minas Passage fishermen also fish for Pollock, haddock, and spiny dogfish. As well, they use drift or gillnetting to catch Atlantic Herring or American Shad.

photo courtesy of: Wikimedia commons

There are also many marine mammals within the Minas Passage. Some of these are: harbour seals, harbour porpoise, grey seals, humpback and minke whales, as well as white sided dolphins. Naturally, these creatures feed off of that which is already present in the Minas Passage, such as species of fish. Consequently, a decrease in any of the prey species would have deleterious effects for the well -being of these considerably more majestic creatures.

Perhaps on the periphery of the Bay of Fundy ecosystem are marine birds. These are creatures such as the Eiders, who dive into the water to get their food. This could put them in contact with a turbine. Still other marine birds which are surface-feeders, such as gulls, shearwaters, and petrels could easily be affected by a difference in turbulence downstream from the tidal generating device.

Challenges faced during Research:

I found the biggest challenge to be the language used in a lot of the reports. Because I am not familiar with biology, I had to research what a lot of the terms being used meant in order to fully understand the implications that were being discussed. To me, this begs the question, how easily accessible are these important documents to the general public? Based on my experience, I would say that there needs to be more information on this issue in layman’s terms. Another challenge during the research aspect of this project was that all lot of the information I found was inconclusive. It is clear that more monitoring in the Bay of Fundy needs to be done in order to properly understand the effects that tidal energy will have on the marine ecosystem.

Conclusion:

 Based on my findings it is apparent that more research is needed to assess the environmental impacts of a tidal energy installation in the Bay of Fundy. This could prove to be a difficult task as a lot of the changes will not be instantly evident. Long-term monitoring of the effects of tidal energy on the biodiversity of this ecosystem is neede.

Bibliography

Force. “The Bay of Fundy.” Accessed March 16, 2012. http://fundyforce.ca/renewable-and-predictable/the-bay-of-fundy/

OEER Association, “Fundy Tidal Energy Strategic Environmental Assessment Final Report.” Report prepared for the Nova Scotia Energy Department, April, 2008.

Richard Inger, Martin J. Attrill, Stuart Bearshop, Annette C. Broderick, W.James Grecian, David S. Hodgson, Cheryl Mills, Emma Sheehan, Stephen C. Votier, Matthew J. Wilt, Brendan J. Godley, “Marine renewable energy: potential benefits to biodiversity? An urgent call for research,” Journal of Applied Ecology, accessed, March 17, 2012, doi: 10.1111/j.1365-2664.2009.01697.x