Understanding the Connection Between Ballast Water and Aquatic Invasive Species in the Great Lakes
The Great Lakes are one of the largest and most unique freshwater systems in the world. Millions of people love the Great Lakes - and so do many aquatic invasive species (AIS).
More than 180 aquatic species have been introduced into the Great Lakes. Fortunately, most of them either did not establish populations or are barely noticeable in the ecosystem. Fifty-five percent of the non-native species that established populations in the Great Lakes during the period following, expansion of the St. Lawrence Seaway (from 1959 onward) are attributed to ballast water discharge although this number could be as high as 70% (Holeck et al. 2004). Over 180 species, 35% have become invasive, which means that they have established abundant populations that have negative consequences for the existing ecosystems, fisheries, and economy of the Great Lakes.
Invasive species frequently have strong negative impacts on fish populations and the fisheries they support. Sea lamprey, alewife, zebra mussels, round gobies, and the spiny water flea are all examples of invasive species that have affected or are affecting Great Lakes ecosystems and fisheries. Along with overfishing and pollution, invasive species are responsible for the loss of 18 fish species in at least one Great Lake.
Unfortunately, many of these species are making their way to the inland lakes of Wisconsin. But, how did AIS arrive in the Great Lakes in the first place?
Understanding the history of how AIS reached the Great Lakes in ballast water, and the implementation of effective ballast water regulations, is the fundamental key to protecting Wisconsin’s inland waters! Using this knowledge as guidance, Wisconsinites can work together to find solutions that will reduce the risk of more AIS using the same pathways to reach our Northwoods lakes.
More than 180 aquatic species have been introduced into the Great Lakes. Fortunately, most of them either did not establish populations or are barely noticeable in the ecosystem. Fifty-five percent of the non-native species that established populations in the Great Lakes during the period following, expansion of the St. Lawrence Seaway (from 1959 onward) are attributed to ballast water discharge although this number could be as high as 70% (Holeck et al. 2004). Over 180 species, 35% have become invasive, which means that they have established abundant populations that have negative consequences for the existing ecosystems, fisheries, and economy of the Great Lakes.
Invasive species frequently have strong negative impacts on fish populations and the fisheries they support. Sea lamprey, alewife, zebra mussels, round gobies, and the spiny water flea are all examples of invasive species that have affected or are affecting Great Lakes ecosystems and fisheries. Along with overfishing and pollution, invasive species are responsible for the loss of 18 fish species in at least one Great Lake.
Unfortunately, many of these species are making their way to the inland lakes of Wisconsin. But, how did AIS arrive in the Great Lakes in the first place?
Understanding the history of how AIS reached the Great Lakes in ballast water, and the implementation of effective ballast water regulations, is the fundamental key to protecting Wisconsin’s inland waters! Using this knowledge as guidance, Wisconsinites can work together to find solutions that will reduce the risk of more AIS using the same pathways to reach our Northwoods lakes.
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History of Ballast Water and AIS in the Great Lakes
When a ship is in its originating port worldwide and being prepared for a trans-oceanic journey, the ballast tank in the ship is filled with water to stabilize the ship during the voyage. When the ship enters the Great Lakes, the ballast water is discharged into the lake to take on cargo and the cargo then serves as ballast. Decades ago, scientists starting noticing that numbers of invasive species were climbing rapidly. In the 1980's they discovered that organisms picked up with the ballast water at the originating ports were then introduced to the Great Lakes ecosystem via the discharged ballast water. These non-native species from around the world includes foreign organisms, fish, plants, sand, sludge, bacteria, and viruses. Their research concluded that ballast water was the main pathway that allowed non-native species to enter the Great Lakes. In the early 1990’s, concerns about damage to the environment and fisheries caused by AIS, raised awareness that the ballast water discharge was the major vector for introducing AIS into the Great Lakes as well as spreading existing AIS throughout the Great Lakes. To protect the long-term sustainability of the Great Lakes, regulating discharge of ballast water was essential and urgent. Since 1993, effective cooperation between the Great Lakes states, the EPA, US Coast Guard, other federal and state agencies, scientists, regulators, organizations worldwide, and the shipping industry have worked together on ballast and AIS issues, helped shape legislation, and implement innovative ballast water regulations. These regulations have largely slowed, if not stopped, new invasions via this pathway. No new invasive species in the Great Lakes have been attributed to ballast water discharge since the discovery of bloody-red shrimp in 2006. But the efforts must remain vigilant. Relaxing requirements would reopen the doors and allow new AIS into the lakes. Controlling a single invasion pathway continues to make a tremendous difference in preventing new AIS from reaching the Great Lakes. |
This short video will show you how AIS from around the world have hitchhiked a ride into our beloved Great Lakes. It also provides insight of how 20 years of AIS regulations and aggressive AIS prevention efforts have been successful at protecting the largest system of freshwater in the world – the Great Lakes.
The video is one in a series developed by Great Lakes Aquatic Nonindigenous Species Information System (GLANSIS) and Michigan Sea Grant. Check out the other videos in the "Managing Great Lakes Invaders" series by visiting the playlist on YouTube at https://www.youtube.com/watch?v=Z4b9u-KRu0U&list=PLrRNRwudM7U90Y614QPP0xFpxGISedvQT&index=2 |