Key Words: bait, microorganisms, Vibrio

The importation of bait creates a potentially important pathway for invasions by nonindigenous species and their associated biota. Since at least 1994, a large nereid polychete worm has been imported from Vietnam and distributed to various places in California, Maryland, and Oregon for use as fishing bait. We measured the abundance of microorganisms, and especially Vibrio bacteria, associated with these bait worms and the material in which they were shipped. Twelve worms were obtained directly from various bait shops in the Maryland/Virginia area. Both the worms and packing materials were analyzed using a range of techniques. We measured the abundance of many taxa by direct counts under a compound microscope. We estimated the abundance of culturable Vibrio bacteria, using standard plating techniques on agar. We also measured the abundance of two serotypes of Vibrio cholerae, using monoclonal antibodies for direct detection. Our results indicate diatoms, ciliates, flagellates, nematodes, and at least seven different genera of amoebae were present in the packing materials. In addition, we found multiple species of Vibrio, including both serotypes of V. cholerae. Although the fate of these organisms upon release remains unknown, our data indicate an active pathway exists for invasion of many different microorganisms and possible pathogens.

Author to contact: Timothy Mullady
Smithsonian Environmental Research Center
PO Box 28
Edgewater MD 21037
T 410-798-4424 x 165
F 301-261-7954
Email: mullady@serc.si.edu

top

Key Words: Black Sea, Ctenophora, Mnemiopsis, distribution, biometry, stomach content

The distribution of Mnemiopsis leidyi, Agassiz 1865, in the Black Sea was determined using plankton samples collected above the anoxic zone (maximum depth 200 m) in the summer, winter, and spring from 1991-1995. Distribution was patchy. Average biomasses of 15 to 500 gm-2 were measured and abundances varied from 10 to 180 individuals m-2. Biomass and abundance peaked in winter and there was a secondary peak in the summer. The distribution of M. leidyi was correlated with hydrographic features in the Black Sea with higher concentrations in anticyclonic gyres. The centers of the two main cyclonic gyres generally had a low biomass of M. leidyi. From July 1992 to March 1995, the populations were largely offshore. M. leidyi were confined to the upper part of the mixed layer both day and night. Some individuals displayed a negative taxis to daylight and, localized below the thermocline at night. Smaller M. leidyi (1.5-2 cm) were present in the winter and individuals reached maximum size in the summer. Although reproduction was continuous throughout the year, there were two distinct peaks: the larger peak in the summer and the smaller peak in the winter. Microscopic analysis of stomach contents showed that copepods and molluscs form their main diet.

top

Key Words: vessel transit, ballast water, exotic aquatic species

Ballast water discharge has been identified as an important means of introducing exotic aquatic organisms to waters well beyond their natural geographic range. Preventative measures such as offshore exchange have been used with some success by vessels carrying exchangeable ballast. Efforts to develop active treatment measures have so far not been successful because of a large number of variables. Major factors that can influence a treatment program include the target organisms which can range from microbes to fish, matrices that include water and sediment, volume of ballast treated, and its application based on onboard equipment or requiring an external source. The treatment itself may have a chemical, physical or mechanical basis. Vessel transit patterns can influence treatment methods, and time of application should be compatible with vessel operational procedures.

Vessel transit patterns will differ among ports because of traffic volumes and transit routes. This factor was examined by tabulating the frequency of visits by overseas and nonregional vessels to Canadian maritime ports at Halifax, Vancouver and Prince Rupert, and freshwater ports on the Great Lakes. There were about 420 vessels from overseas or distant ports of departures that visited the Port of Halifax between 1992 and 1997; 2400 vessels to the Port of Vancouver between 1995 and 1997; 1170 vessels to Port of Prince Rupert between 1992 and 1997; and 880 vessels to Great Lakes ports between 1989 and 1997. Tabulation on the basis of the number of visits indicated that 46 to 71% of the vessels visited a port once during the 3 to 9 year periods reviewed. Furthermore, 68 to 96% of the vessels averaged 2 or less visits per year over the same period. The relatively high level of single visits and low frequency of repeat visits to these ports could deter the adoption of possible regulations that would require the installation of onboard ballast water treatment equipment on vessels before port entry, unless this requirement is applied at the international level.

Voluntary or mandatory exchange is used by some ports as a preventative measure, but its effectiveness is limited to vessels carrying exchangeable ballast. Offshore ballast exchange could be effective at the Ports of Vancouver and Prince Rupert because over 90% of the total cargo handled is exported, therefore most of the inbound vessels arrive in ballast. In contrast, ballast water exchange may not be an effective preventative measure on the Great Lakes because about 50% of the total cargo handled is exported, and over 80% of the overseas vessels enter with no exchangeable ballast on board (NOBOB).

A vessel monitoring program may be required to assess the level of compliance of a ballast water treatment program. Annual visits by nonregional vessels averaged about 400, 1820, 310 and 470 for the Ports of Halifax, Vancouver, Prince Rupert and ports on the Great Lakes. The frequency of these visits may not be a limiting factor in their assessment because arrivals of 1 to 3 vessels per day were the most frequent at the Ports of Halifax and Prince Rupert, and ports on the Great Lakes, but could be a factor at the Port of Vancouver where 5 to 9 vessels arrive per day. Access to vessels arriving at the three maritime ports for inspection and possible treatment could be a problem. Access to vessels entering the Great Lakes is greatly facilitated by the need for all vessels to pass through a series of seven locks between the city of Montreal and Lake Ontario.

Author to Contact: Arthur J. Niimi
Department of Fisheries and Oceans
Canada Centre for Inland Waters
867 Lakeshore Road
Burlington, ON L7R 4A6 Canada
T 905-336-4868
F 905-336-6437
Email: niimia@dfo-mpo.gc.ca

top

Key Words: Hemigrapsus sanguineus, geographic distribution, crab, range extension

Hemigrapsus sanguineus, a crab (family Grapsidae) native to the western North Pacific Ocean, was established on the east coast of the United States by 1990. Its abundance noticeably increased between 1993 and 1994 in Buzzards Bay, Massachusetts. In 1996, we received reports of the crab in Sandwich and Wellfleet on Cape Cod, and on Martha's Vineyard. Since 1996, we have been tracking the northward spread of the species and monitoring changes in newly-established populations in Cape Cod Bay, Nantucket Sound, and Narragansett Bay. In 1996, density estimates were made on populations in Sandwich (Cape Cod Bay) and Washburn Island, part of Waquoit Bay National Estuarine Research Reserve (Nantucket Sound). In 1997, the population on Washburn Island had increased more than ten-fold. Hemigrapsus sanguineus was also present in 1997 in Manomet (Plymouth, MA) and near Brant Rock (Marshfield, MA), along the shore of Cape Cod Bay. By 1998, H. sanguineus was found as far north as Scituate, MA, and populations in Plymouth and Marshfield had doubled in size. In addition, well-established populations occurred on Hope Island, in the middle reaches of Narragansett Bay.

Author to Contact: Nancy J. O'Connor
Department of Biology
University of Massachusetts Dartmouth
285 Old Westport Road
N. Dartmouth, MA 02747-2300
T 508-999-8217
F 508-999-8196
Email: noconnor@umassd.edu

top

Key Words: ballast water treatment, treatment options, future research direction

A number of research groups have been working on ballast water treatment options, resulting in a considerable refining of the treatment options which can be applied to ballast water treatment. This paper summarises briefly the options which are presently appropriate for ship-board ballast water treatment, discusses the limitations of these options and presents a list of the options which can realistically be expected to work. Research required to develop these technologies are discussed. Methods which are recommended for further research include: further examining the efficiency of ballast exchange processes, filtration, UV irradiation, heat treatment and other biocidal approaches. Research methods include computer modelling, laboratory tests, pilot tests and field testing, depending on the current state of knowledge for each option.

An important aspect of ballast water treatment is the need to compare the costs of the treatment options. For this to be done effectively standards need to be developed for ballast water treatment. At present there are two incompatible de facto standards based on the efficiency of ballast water exchange and on the inactivation of hypnocysts of some species of dinoflagellate algae. To accurately compare treatment options requires biological research which begins to identify the effectiveness that is required to stop a number of organisms from surviving all stages of the ballast water transport cycle. As this understanding begins to develop, the treatment options can be compared on the basis of the cost required to meet set standards of discharge for a range of organisms.

School of Engineering
James Cook University
Townsville, QLD 4811
Australia
T +61 7 4781 5081
F +61 7 4775 1184
Email: eng-djo@jcu.edu.au

top

Key Words: aquatic nuisance species, database, World Wide Web, introduction, spread, impacts, control, Gulf of Maine, Northern Atlantic, Mid-Atlantic, Southern Atlantic, Gulf of Mexico, Pacific Northwest, Great Lakes, information, education, clearinghouse

he National Aquatic Nuisance Species Clearinghouse serves as a major link between the aquatic nuisance species research community and a wide array of end-user audiences, encourag-ing and facilitating the transfer of aquatic nuisance species research information and technology among universities, governmental agencies, industries, and special interests through-out North America and worldwide. The Clearinghouse also plays a high-profile role as a primary nexus for identifying completed, current, and proposed aquatic nuisance species research activities and for linking researchers with similar interests pertaining to important marine and freshwater aquatic nuisance species introduction, spread, research, and policy initiatives.
The Clearinghouse addresses marine and freshwater aquatic nuisance species throughout the Gulf of Maine, Northern Atlantic, Mid-Atlantic, Southern Atlantic, Gulf of Mexico, Central and Northern California, Pacific Northwest, and Great Lakes regions, as well as North American inland river systems, and is the home of North Americaís most extensive technical library of published research and other materials pertaining to zebra mussels (Dreissena polymorpha) and "quagga" mussels (Dreissena bugensis), and is in the process of building libraries on the Atlantic green crab (Carcinus maenas), the Amur River Corbula (Potamocorbula amurensis), the Chinese mitten crab (Eriocheir sinensis), the grass carp (Ctenopharyngodon idella),the Suminoe oyster (Crassostrea ariakensis), Limnoperna fortunei, shipworms (Teredo navalis), the brown mussel (Perna perna), the Asian clam (Corbicula fluminea), the blue mussel (Mytilus edulis), the dark false mussel (Mytilopsis leucophaeata), the Eurasian ruffe (Gymnocephalus cernuus), the round goby (Neogobius melanostomus), the tube-nose goby (Proterorhinus marmoratus), the rudd (Scardinius erythrophthalmus), the spiny water flea (Bythotrephes cedarstroemi), and the blueback herring (Alosa aestivalis). All of the information in the Clearinghouse is accessible to any researcher, agency, industry, utility, student, or other individual or group having need of the information. Most publications in the library can be obtained in hardcopy on interlibrary loan directly from the Clearinghouse.

A new, searchable electronic database of the Clearinghouseís Technical Library Bibliography is now available on the Clearinghouseís World Wide Web home page. Citations include: author(s), title, document source and date, an annotation, whether the document is a journal article or other type of publication, document length, the language in which the document is written, whether the document is available on interlibrary loan from the Clearinghouse or direct from some other source, and the copying/mailing fee if the document is available from the Clearinghouse. The database is keyword searchable (via a 170+ keyword, four level search outline) and plain language full text searchable. Documents which are available directly from the Clearinghouse on interlibrary loan can be ordered on-line by means of a convenient order form at the end of each search result report. The World Wide Web address for the database is: (http://cce.cornell.edu/seagrant/nansc/anslibsindex.htm)

The web site also contains a series of detailed maps charting the range expansion of the zebra mussel and the "quagga" mussel in North America since 1989, as well as information on a number of other informational and educational materials available from the Clearinghouse.

This poster presentation will introduce attendees to the new National Aquatic Nuisance Species Clearinghouse Searchable World Wide Web Aquatic Nuisance Species Database. A laptop computer containing a working copy of the Clearinghouseís entire web site on CD will be utilized, linked to a data projector, to enable attendees to explore the Clearinghouseís web site, especially the searchable database, including being able to perform keyword and full text searches of the database.

Contact: Charles R. OíNeill, Jr.
National Aquatic Nuisance Species Clearinghouse
New York Sea Grant, Morgan II, State University College
Brockport, NY 14420
Phone: (716) 395-2638
Fax: (716) 395-2466
E-mail: coneill@cce.cornell.edu

top

Key Words: Botrylloides, Styela, Ascidiella, Diplosoma, predation, ascidians, sessile community

Within the last 25 years, four species of sessile marine ascidians, Botrylloides diegensis, Styela clava, Diplosoma macdonaldi, and Ascidiella aspersa, have invaded marine rocky subtidal habitats of New England. Although all three species produce short-lived, poorly dispersing larvae, they have spread over a broad geographic area from Connecticut to Maine. Within this range their local distributions are fairly patchy, as they occur in high abundance at some sites while being rare or absent at similar sites nearby. Since 1987 we have been conducting experimental field studies in Vineyard Sound and eastern Long Island Sound, examining the ecological interactions between these ascidians and the native community. We have found that: (1) adult ascidians transplanted to sites where they are rare or absent survive and grow at rates similar to those found at sites where they are abundant, (2) these ascidians are not inhibited from recruiting onto substrates occupied by native species, (3) at field sites where these ascidians are rare, 1-3 day-old recruits are preyed on by at least three species of very abundant small snails, Anachis lafresnayi, Anachis avara, and Mitrella lunata, (4) juvenile 1-2 week-old Styela were also preyed on by fish, mostly the cunner, Tautogolabrus adspersus, and (5) Botrylloides and possibly Styela seem to escape predation at an earlier age and smaller size than similar native species. From our studies we feel that these species are able to invade local communities because: (1) they have short range larval dispersal that allows them to build up abundant local populations, (2) their recruitment is not strongly inhibited by native sessile species, and (3) they are less vulnerable to predation than similar native species. However, they do appear to be excluded from some habitats such as the more exposed open coast and even when present they seem to become well-integrated into the local communities.

Author to Contact: Richard W. Osman
Academy of Natural Sciences
Estuarine Research Center
10545 Mackall Road
St. Leonard, MD 20685
T: 410-586-9700
F: 410-586-9705
Email: osman@acnatsci.org

top

The Japanese shore crab, Hemigrapsus sanguineus (de Haan), was recently introduced to the northeast coast of the USA. The crab has established intertidal populations extending throughout the Middle Atlantic Bight. This study defines early-life-history characteristics that are germane to range extension in this species. Results of the investigation showed that the spawning season of H. sanguineus continues for at least 4 mo in the southern Middle Atlantic Bight. This is considerably longer than the spawning seasons of co-occurring native crabs. Eggs hatch about 14 d after extrusion, and females have the potential to produce several broods each year. Zoeal larvae are tolerant of a wide range of temperature/salinity combinations, and mean duration of zoeal development ranges from approximately 16 d at 25 degrees C to 55 d at 15 degrees C. At 25 degrees C zoeae are capable of development to the megalopa stage at salinities as low as 15 parts per thousand. At lower temperatures the zoeae require salinities above 20 parts per thousand. The megalopa stage appears to have more stringent temperature/salinity requirements, which may restrict H. sanguineus to rocky shores of the coastal ocean and the adjacent high-salinity regions of the estuary. Under these conditions megalopae molt to the first juvenile stage in approximately 25 d post hatching. Newly metamorphosed crabs reach the fifth juvenile instar in 35 d. Dry-weight growth of zoeal larvae and early stage juveniles is exponential at respective rates of 23 and 8 % of body weight per day.

Author to Contact: Susan Park
University of Delaware
College of Marine Studies
T: (302) 644-0279
E-mail: spark@udel.edu

top

Back to Abstracts, Page 8

Forward to Abstracts, Page 10

Back to HTML Abstracts Page

Back to Main Conference Page