Collaborations to prevent the spread of invasive species
Cooperative Research Unit Corner, Wildlife Management Institute Bulletin August 2013.
Christine M. Moffitt
Idaho Cooperative Research Unit
Increasingly, managers are concerned about the risks of aquatic invasive species affecting the
habitat and native species communities. Two USGS scientists and several generations of
graduate and undergraduate students are engaged to provide solutions that help managers reduce
the likely transport of aquatic invasive species. Dr. Barnaby Watten of the USGS Leetown
Science center and Dr. Christine Moffitt of the Idaho Cooperative Fish and Wildlife Research
Unit have been collaborating for nearly 10 years on developing and testing tools for containing
and preventing the transport of invasive mollusks. Their first studies focused on fish hatcheries,
where the source water springs were infested with New Zealand mudsnails. Watten proposed the
use of a hydrocyclone to remove invasive snails from hatchery inflow. The hydrocyclone is an
instrument with no moving parts that can separate particles based on their specific gravity.
Cyclonic separation is widely used in mining and other industrial venues. Moffitt and graduate
student Jordan Nielson found that the prototype system installed at the Hagerman National Fish
Hatchery in southern Idaho was 100 % effective in removing the snails from intake waters. The
researchers also collaborated on studies to show that use of pressurized CO2 was effective in
treating and disinfecting tank systems that contained invasive mollusks. Nielson received his
Masters degree from the University of Idaho, and is now the Aquatic Invasive Species
coordinator for the Utah Division of Wildlife Resources, where he works with many hatcheries,
and water bodies to prevent and control infestations in state waters. Another tool that has been
tested in their field trials is a mixed cell raceway system. Watten and colleagues designed this
system to retrofit older hatchery ponds that were highly ineffective for removal of solids. They
worked with staff at Dworshak National Fish Hatchery in Ahsahka Idaho who had retrofit two
Burrows ponds with a mixed cell system. In these studies, graduate student Kelly Stockton,
Watten and Moffitt, along with undergraduate assistants, and hatchery staff tested the efficiency
of this system in removing particles the size of New Zealand mudsnails from the raceway
system. They found that particle removal was very complete, and if fish had injested snails, they
could be depurated in a system such as this, as long as snail free water was available to prevent
re-infection. An additional benefit to this rearing system is that it maintains high quality water
distributed throughout the system, and hatchery managers can rear more fish per gallon of water.
In addition to its potential use for invasive mollusks, the rearing system has shown to be a more
productive and water efficient rearing system for salmonids. After completing her master’s
degree, Kelly Stockton now is employed by Marrone Bio Innovations, and works with testing of
invasive quagga mussels.
Currently, Moffitt and Watten are collaborating on a project evaluating elevated pH as a tool to
prevent transport of invasive mollusks and other invasive species in ship ballast and other tank
systems. Ballast water discharges are believed to be the major source of invasive species and
there is need for methods to control and prevent further introductions using disinfection systems
that are economical, environmentally safe, and effective. Several authorities are engaged in
management of ballast, at the state, region and international level. The new U.S. Coast Guard
regulations require that all new and existing vessels meet standards to guarantee treatments are in
place to reduce the risks of introducing harmful species with ballast discharge. Our research
shows that creating an elevated pH with simple compounds such as NaOH can provide an
economically feasible method of disinfecting tanks, not harm the equipment and the pH of
treatment can be neutralized with CO2 to achieve an environmentally safe discharge. This project
also involves graduate and undergraduate students as active researchers. In September Watten,
Moffitt, and graduate student Amber Barenberg will be conducting shipboard trials in Lake
Superior.