LAUSR

border of Canada and the United States hold one-fifth of Earth’s surface fresh water, and cover almost 250,000 square kilometres — an area larger than the United Kingdom. They are home to 3,500 species of plant and animal, including more than 170 species of fish. Some 30 million people live in their watershed. Their scale and natural beauty are inspiring, yet for hundreds of years they have also been viewed as a resource to be conquered. Now, a perfect storm of invasive species, pollution, climate change and other pressures is playing out in the region. In his engaging The Death and Life of the Great Lakes, journalist Dan Egan traces the lakes’ history, from the arrival of the first Europeans, such as French explorer Jean Nicolet — who in 1634 set out on Lake Michigan in a birch-bark canoe, looking for a passage to Asia — to the present. Egan’s focus is on invasive species that tagged along as humans re-plumbed the Great Lakes to serve their needs. Starting with the parasitic sea lamprey (Petromyzon marinus), which had spread across the Great Lakes by the 1930s, these have dramatically altered the lake system and devastated native populations. Egan tells a tale of human ambition, ingenuity and hubris. He also speaks of redemption and opportunity. The Great Lakes had a central role in the industrialization of the continent, and have thus seen massive engineering projects with two primary goals: to open up the North American interior to shipping, and to dispose of its sewage. These, Egan shrewdly dubs the front and back doors. The completion of the first canal and locks goes back to 1781, culminating in 1959 with the opening of the Saint Lawrence Seaway. As seagoing vessels made their way deeper into the Great Lakes, they brought with them freshwater species from around the world, especially in ballast waters used to stabilize ships. Along with the lampreys, the protagonists of Egan’s story are alewives (a type of herring, Alosa pseudoharengus) and zebra and quagga mussels (Dreissena polymorpha and Dreissena bugensis), which have successively upended the food web and overtaken the ecosystem. The management responses to these invasions parallel the broader history of environ mental-restoration efforts. A selective poison was developed to control lampreys in the 1950s, after fisheries collapsed in Lake Michigan, Lake Huron and Lake Superior. Non-native coho and Chinook salmon (Oncorhynchus kisutch and Oncorhynchus tshawytscha, respectively) were introduced to tackle alewives, starting in the 1960s. The dual mussel infestation that began in the late 1980s continues but, in a fascinating twist, native whitefish (Coregonus clupeaformis) seem to be evolving to feed on the mussels and on another E N V I R O N M E N TA L S C I E N C E S