Topic 2: The role of dams in ecosystem fragmentation, part II- When most people think of the bio/ecological impacts of dams, they usually think of Salmon. Today, I took the opportunity to talk about some of my work as an environmental consultant on the role of dams in the lives of endangered populations of freshwater mussels in New England. Mussels have a two-stage reproductive cycle in which parasitic larvae called glochidia latch onto the gills of a host fish as an evolutionary mechanism for species distribution. Anything (such as dams or even poorly-designed culverts) that prevent the free travel of host fish will have an overall negative impact on mussel populations as well, however, dam impoundments also create excellent habitat for some species such as freshwater mussels. Generally, we think of dam building as being disruptive to habitats, but dam removal can also be disruptive to a small minority of individuals from species that, as a whole are adversely affected by the dam's presence. The presence sensitive species in anthropogenic environments such as impoundments creates obvious ethical issues that need to be considered during dam removal and, if certain protected species are present or suspected to be present there are legal issues as well. Considerations such as this also add to the cost of dam removal (which is tens to hundreds of thousands of dollars for relatively small structures or much more for major works).
Topic 2: We then turned our attention to the largest dam in the world- the Syncrude Tailings Dam in Alberta, CA. The activities of Syncrude, Suncor, and Shell Canada way north of the border touches upon three topics that are relevant to this course:
1. ...largest dam in the world...
2. Water Quality: The extraction of highly viscous hydrocarbons from tar sands requires the use of 2-4.5 units of water for each unit of oil recovered. Even with water recycling programs in place, this means that extraction activities in an area that is producing 1.126 million barrels per day (a barrel contains 42 US gallons) is going to produce a great deal of low quality water- and will have to figure out a way to deal with the implications of this.
3. Water footprint: The vastly higher water requirements for Canadian tar sand oil above and beyond those associated with the extraction of conventional petroleum resources demonstrates that the volume of embedded water that we as individuals and as a society use are dependent not only on what we use and how much of it we use but also on the means of production of the product or resource.
There will be no reading assignment for this weekend... ...with the assumption that you will be getting in the lion's (or lioness') share of your BC/BM reading.
Slides shown in lecture today are available as a .pdf on Sakai.
The my maps page has been updated with the locations mentioned in today's lecture.
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