This database, created in 2008, catalogs key research documents regarding the 15 non-indigenous species found in Prince William Sound at that time. Also included are key research documents on various ballast water treatment technologies that may be successful in decontaminating ballast water laden with non-indigenous aquatic species of threat to Prince William Sound and the northern Gulf of Alaska.
Information is also included on two species not yet found in Alaskan waters, but of serious concern: the Chinese Mitten Crab and the European Green Crab. Currently found along the west coast of the Unites States, the Chinese Mitten Crab and European Green Crab are considered a serious potential threat due to the proximity of their geographical distribution to Alaskan waters, their ability to survive and adapt in new environments, and the negative ecological impacts they have had in areas already invaded.
How to Use This Database
You may search this database by author, title, port, technology, species, or policy. The results will include:
• The document’s abstract
• The document’s bibliographic information
• In some cases, a PDF link to a full copy of the work.
However, some documents are pending copyright permission before being available as a full copy PDF on this site.
How Material was Selected for This Database
Material on Specific Species
In 2008, PWSRCAC developed a bibliographic database of information on non-indigenous species of threat to Prince William Sound and the northern Gulf of Alaska.
The database provides access to literature on the 15 non-indigenous aquatic species already found in tanker ballast water that is currently discharged into Prince William Sound.
Six additional categories were also added to the species keyword index: Chinese Mitten Crab, green crab, aquaculture issues, transgenic issues, algae (general), and aquatic invasions (general). Chinese Mitten Crab and European Green Crab were added to the list of species of concern because of their proven invasiveness, their negative ecological and economic impact in areas invaded, and their geographical extent along the West Coast of the United States. Although these two species are not yet known to have invaded the waters of Alaska, their ability to survive and adapt to new environments makes them a potential future threat in Alaskan waters. Other topics that were included in the database address issues such as aquaculture, transgenic (genetically modified organisms), and the general issues of aquatic invasions. Papers were selected for these topics because they are directly related to issues that currently have or will potentially have major implications for invasive marine organisms.
As a result of continued increased shipping throughout the world and continued climate changes, waters in the northern latitudes, including Alaska, will likely see an increase in marine invasions.
As the ecological and economic impacts of NIS become better known, the urgency to study their biology, ecology, and invasiveness will undoubtedly increase.
It is the council’s goal to conduct periodic searches of recently published research to keep abreast of emerging NIS issues in ports of concern; identify potential alien invaders to Prince William Sound, especially species that have the ability to adapt to northern latitudes; and update the council’s database with the most current literature available.
Material on Ballast Water Treatment Technologies
PWSRCAC has developed a bibliographic database of information on various ballast water treatment technologies that may be successful in decontaminating ballast water laden with non-indigenous aquatic species of threat to Prince William Sound and the northern Gulf of Alaska.
This database provides access to literature on 29 technology options for treating ballast water either on board the tanker or at a shore-side treatment facility.
The technology options that were identified in the literature were categorized by process type: chemical, mechanical, biological, physical, and operational treatment. References were located by conducting a web search; using available reference material from PWSRCAC’s library; reviewing ballast water technology conference proceedings, and consulting with ballast water treatment vendors, the SeaGrant Program, the International Maritime Organization (IMO), and U.S. Coast Guard.
Well over 100 references were located, and the top 50 key references pertaining to PWSRCAC’s area of concern were used to populate the database. Not all technologies are equally represented in the search results. Technologies that have shown promise and that are more applicable to large crude oil tanker shipboard treatment or high volume shore-side treatment are prioritized.
Ballast water exchange is currently the only regulated technology for ships entering U.S. waters. However, the Alaska oil tanker trade is exempt from those regulations. In this process, ships exchange their ballast water with seawater on the high seas in organism-depleted deep water. Ballast water is exchanged by either continually flushing tanks or emptying and refilling tanks. While ballast water exchange does remove many unwanted non-indigenous species, it does not purge all the invasive organisms, does not address disease-causing pathogens, and does not treat tank sediment or non-pumpable ballast; ballast water exchange can also be operationally unsafe.
In addition to ballast water exchange, the following are emerging as potentially viable technologies for high volume ballast water treatment: filtration, cyclonic separation, ozone, ultraviolet irradiation (UV), in-transit heat, ultrasound, chlorine dioxide, or a combination of these technologies.
When selecting an appropriate ballast water treatment technology, it is critical to determine the targeted alien invader, as certain technologies are better suited for treating particular NIS than others. For larger size NIS a filtration system is essential to limit the amount of NIS initially taken into the ship’s tanks. However, for microscopic NIS, additional chemical, physical or heat treatment would be required to kill those microscopic NIS that bypass the filtration system. In selecting a technology for PWS, a focused alien invader target or range of targets must be identified.
The IMO has found that treatment technology should be: 1) safe; 2) environmentally acceptable; 3) practical; 4) cost effective; 5) biologically effective. Very few technologies currently meet all five criteria. One of the most significant problems in evaluating technology options is the lack of technology standards. Researchers and entrepreneurs continually point out the need to develop and implement international standards and procedures for the evaluation and approval of new ballast water treatment systems.
Oil residue in water at the Ballast Water Treatment Facility–photo by Susan Sommer, PWSRCACThere are both shipboard and shore-side treatment options available. While much of the Prince William Sound tanker company efforts have been focused on shipboard treatment options, cost effective shore-side treatment options may also be an alternative. For example, a final treatment stage could be added to the Ballast Water Treatment Facility (BWTF) already available at the Valdez Marine Terminal (VMT). The economy of scale, dedicated and predictable trade route, and the number of currently available shore-side treatment options available may make this a more cost effective and quicker option for consideration. Both segregated and unsegregated ballast could employ the final ballast water treatment stage designed for NIS removal.
Shipboard treatment options are full of technical and economic challenges; however, they may be the only option in unpredictable, widely varying trade routes that don’t lend themselves to shore-side treatment options. Technical challenges for shipboard treatment options include: vessel safety, fire hazards, corrosion, space limitations, vessel design limitation, inability to treat full volume during transit route, and “dead spots” in tanks that remain untreated. While shipboard ozone treatment has been studied as an option for Prince William Sound, research shows that ozone can be extremely effective for microscopic organisms, but large species including the Chinese Mitten Crab experience a high survival rate.
In summary, most ballast water treatment technologies are still under development. Ballast water exchange remains the primary method in use worldwide. So far the most effective and promising technologies involve a combination of technologies using primary treatment options (filtration or cyclonic separation) followed by a biocidal treatment.
Periodic searches of recently published research will be conducted by the council to keep abreast of current literature for new and emerging technologies. As national and international laws continue to require increasing improvements in ballast water technology, universities, government agencies, and private companies are racing to develop commercially viable technologies. The quality and quantity of technology treatment options will continue to expand and should be watched closely over the next couple of years, while the search for a viable treatment technology for the Prince William Sound