Global commerce for the Great Lakes brought with it scores of invasive species. “A ship coming from the Baltic may carry an uninvited international hitchhiker,” says Twiss.
One of those hitchhikers, says Twiss, was the zebra mussel -- a small aquatic animal originally found in Russia. The mussel arrived around 1988 and began to breed. Since each female produces one million eggs a year, the burgeoning mussel population has had a drastic effect on the ecology of the Great Lakes.
For instance, the mussels changed the aquatic food supply by filtering phytoplankton, and markedly increased the clarity of Great Lakes water in the process. But the cleansing deprived other species of food.
“This caused lake trout to starve,” says Twiss, an associate professor of biology and director of the Great Rivers Center at Clarkson University. He said the mussels have also turned some beaches into “middens,” or dumps of empty mussel shells.
The zebra mussel population is controlled in part by the appetite of another species that also arrived via the Seaway – the round goby, a fish native to Eastern Europe’s Black and Caspian Seas. The goby showed up in 1990 and began to feast on the mussels. This kept the gobies well fed and helped to control the zebra mussel population, but produced yet another environmental shift. “Things like the sturgeon and the small mouth bass are thriving because they eat the goby,” Twiss explains.
It is a case of one thing leading to another, and Twiss wants to better understand how this constantly evolving system works. It is familiar territory; Twiss, a Yankee who grew up on the north shore of Lake Huron in Canada, has been around the Great Lakes all his life.
Now he is trying to find out what makes the system tick, with a particular focus on the little-studied 115-mile International Section of the St. Lawrence River which forms part of the boundary between New York State and Ontario. But Twiss and his research colleagues recognize that the environmental change wrought by invasive species can’t be easily reversed.
Rapid ecological change has been a constant in the region since the arrival of European settlers. Since the 1800s, more than 136 invasive fish, algae, invertebrate, and plant species have colonized the Great Lakes, according to the U.S. Geological Survey. An early arrival was the sea lamprey, an eel-like primitive fish with a vampire’s eating habits. The lamprey hooks its prey with its sucker mouth, drills a hole with its teeth, and then drains its victims of fluids and blood. Its prey includes salmon, lake trout, and sturgeon. The lamprey, which was discovered in Lake Ontario in the 1830s, may have entered through the Erie Canal.
But the St. Lawrence Seaway set off a new round of upheaval by allowing foreign invaders to reach the Great Lakes as stowaways in ship ballast, the extra water that ships carry to control stability in the water. When this water was dumped, invaders were set loose. The zebra mussel is believed to have arrived this way. New regulations now control where ballast can be emptied, but they came too late.
The Seaway was built to spur the economies of adjoining states and Canadian provinces by allowing ocean ships to travel unimpeded from the Atlantic to Duluth, Minn. Unfortunately, when the Seaway’s 50th anniversary arrived, the media focused on the undesirable changes it had brought.
One of these changes came with the damming of the Long Sault Rapids, which allowed the installation of locks to handle big ships. “They drowned the rapids,” says Twiss. This removed the natural fluctuations in water levels, so that cattail marshes took over sections of the river where fish once spawned.
It might seem logical to simply restore fluctuating water levels, and Twiss says several plans to do this have emerged. But Twiss cautions against haste. The danger is that fixing one problem may create another.
One sticking point is that wetlands are a natural reservoir for mercury because they aren’t flushed by changing water levels. The river has been dammed for half a century and a lot of mercury has accumulated. “It potentially would be released in bulk if the water were allowed to rise and fall more naturally,” Twiss says. In turn, this might render the fish in the river contaminated for human consumption, a warning not heeded by the burgeoning Bald Eagle population on the river.
It would amount to “yet another disturbance, when we already don’t understand how things work now,” Twiss adds. He is working with a colleague from the University of Ottawa to study the area where the rapids once lay. But even as they work, other changes may be taking place.
“It’s like bobsledding,” observes Twiss. “You can’t get off, and it changes direction so rapidly it is difficult to keep your bearings. For a scientist, it’s very challenging. Just when you think you understand the system, something else happens.”
Clarkson University launches leaders into the global economy. One in six alumni already leads as a CEO, VP or equivalent senior executive of a company. Located just outside the Adirondack Park in Potsdam, N.Y., Clarkson is a nationally recognized research university for undergraduates with select graduate programs in signature areas of academic excellence directed toward the world’s pressing issues. Through 50 rigorous programs of study in engineering, business, arts, sciences and health sciences, the entire learning-living community spans boundaries across disciplines, nations and cultures to build powers of observation, challenge the status quo, and connect discovery and engineering innovation with enterprise.
Michael P. Griffin | Newswise Science News
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
100 % Organic Farming in Bhutan – a Realistic Target?
15.06.2018 | Humboldt-Universität zu Berlin
In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.
Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...
Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...
Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.
Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...
The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.
Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.
An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.
Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...
13.06.2018 | Event News
08.06.2018 | Event News
05.06.2018 | Event News
22.06.2018 | Materials Sciences
22.06.2018 | Earth Sciences
22.06.2018 | Life Sciences