Key Words: microbes, Chesapeake Bay, ballast water
Perhaps the least-studied aspect of marine bioinvasions is the transfer of nonindigenous microbes. Given the high densities of naturally occurring bacteria, viruses, and phytoplankton in coastal waters, it seems inevitable that high numbers of microorganisms are transported globally via ballast water. As a first step in evaluating the rate and extent of this transport, we boarded vessels, primarily colliers arriving in Norfolk, VA and Baltimore, MD, to quantify the microbes present in their ballast water tanks. We used epifluorescence microscopy to measure abundances of bacteria and virus-like particles and incorporation of DNA precursors to determine bacterial production rates. We also measured the ballast watersí temperature, salinity, and concentration of chlorophyll a. Direct counts of bacteria and virus-like particles ranged over two orders of magnitude, from 107 - 109 cells per liter and 108 - 1010 cells per liter, respectively. Similarly, bacterial production rates, expressed as incorporation of tritiated thymidine into DNA, varied broadly, from 0.40 - 13 picomoles per liter per hour. Chlorophyll a values ranged from 0.005 - 0.04 micrograms per liter. Relationships between hydrographic characteristics of ballast waters and microbial signatures will be discussed.
Author to Contact: Lisa Drake
Department of Ocean, Earth and Atmospheric Sciences
Old Dominion University
4600 Elkhorn Avenue
Norfolk, VA 23529
T: 757-683-5060
F: 757-683-5303
Email: ldrake@odu.edu
Key Words: Chesapeake Bay, biological invasions, historical survey, cryptogenic species, ballast water, ecological impacts
Chesapeake Bay has been subject to biological invasions since the start of European colonization in 1609. In a comprehensive analysis of the historical patterns of invasion, we identified 160 nonindigenous species that now occur in tidal waters of the Chesapeake. These species represent 17 different phyla, including vascular plants and invertebrates to vertebrates and single-celled protistan pathogens. Invasions are documented from all regions and habitats of Chesapeake Bay. Source regions and transfer mechanisms have varied greatly over time and by taxa, and the rate of invasions has increased in recent decades. In addition to known invaders, the Chesapeake has a high proportion of cryptogenic species (i.e., those of unknown origin). Historical surveys and first records of many taxa are relatively recent, occurring well after possible transfer by European colonization. Of 800 species of benthic invertebrates and macroalgae in Chesapeake Bay that we have examined, 30% (237 species) also occur in Europe, suggesting that many unsuspected introductions exist. Today, multiple pathways for new invasions are still active in Chesapeake Bay. Shipping is presently the largest pathway for the transfer and release of organisms to the region. Two recent ballast-mediated invasions underscore the continued importance of this vector. Although invasions have had significant ecological and economic impacts in the Chesapeake, the consequences of most marine invasions remain unmeasured here and elsewhere.
Author to Contact: Paul Fofonoff
Smithsonian Environmental Research Center
Edgewater MD 21037
T 410-798-4424 x337
F 301-261-7954
Email: fofonoff@serc.si.edu
Key Words: hydroids, range of distribution, taxonomy
Cordylophora is a colonial hydroid occurring in brackish and freshwater habitats. Records indicate that the distribution of this hydroid is expanding globally by rapid boat travel and ballast discharge. Cordylophora is becoming more common in freshwater habitats due probably to an increase in salts (chlorides) from runoff with road salts. Currently we are documenting the distribution of Cordylophora populations in several freshwater systems in the United States. Recently Cordylophora posed a problem to a local power plant and we were hired to curtail hydroid growth in pipes. Laboratory experiments using cultured colonies of Cordylophora indicate that temperature is most effective (compared to chlorine) in killing or curtailing hydroid growth. We are also beginning preliminary DNA analyses on various populations of Cordylophora to address a discrepancy of species identification found in the literature. DNA analyses (characterization of 16S rRNA) along with interbreeding experiments will assist in clarifying the taxonomic confusion currently existing for Cordylophora. Elucidation of the overall distribution patterns and genetic structure of various hydroid populations will assist in confirming or modifying the taxonomy and species composition of an organism that may be becoming a more visible invading species.
Author to Contact: Nadine C. Folino
Biology Department
Wheaton College
Wheaton, Illinois 60187
T 630-752-7038
F 630-752-5996
Email: nadine.c.folino@wheaton.edu
Key Words: Codium fragile ssp. tomentosoides, urchin, grazing
This study compared the grazing pressure on the introduced, subtidal Codium fragile ssp. tomentosoides in the Atlantic Ocean to grazing pressure on the endemic, intertidal Codium fragile in the eastern Pacific Ocean. In laboratory experiments conducted on the Atlantic coast, the sea slug Placida dendritica consumed significant amounts of the algae but was not dense enough in situ in the Gulf of Maine or Long Island Sound during 1998 to affect populations of C. fragile ssp. tomentosoides. The sea urchin S. droebachiensis consumed C. fragile ssp. tomentosoides in single diet experiments in the laboratory but not in field transplants. In the Pacific (Friday Harbor, Washington) both S. droebachiensis and S. franciscanus consumed C. fragile in laboratory experiments, however S. franciscanus consumed significantly more C. fragile than did S. droebachiensis. Furthermore, preliminary results suggest that large urchins are more effective grazers on C. fragile than small urchins. In field experiments, C. fragile transplanted to S. franciscanus barrens were heavily grazed. These results suggest that grazing pressure from S. franciscanus is responsible for confining C. fragile primarily to low intertidal in areas in the eastern Pacific. In contrast, a lack of this grazing pressure in the Atlantic may have allowed C. fragile ssp. tomentosoides to spread to subtidal areas.
Author to Contact: Aaren Freeman
Northeastern University
Marine Science Center
East Point, Nahant, MA 01809
T: (781) 581-7370
F: (781) 581-6076
Email: afreeman@lynx.neu.edu
Key Words: ballast water exchange, invasion rate
Ballast water exchange is being promoted nationally and internationally as a management strategy to (1) decrease the abundance of coastal organisms within shipsí ballast water and thereby (2) reduce the risk of future invasions by nonindigenous species. We are measuring the efficacy of two distinct exchange methods (Flow-Through and Empty-Refill) to remove organisms from ballast tanks across multiple ship types. Physio-chemical and biological tracers were used to estimate the effects of exchange on different components of ballasted communities. Preliminary results, based on salinity and Rhodamine dye tracers, indicate significant water mass exchange (>80%) for both Flow-Through and Empty-Refill methods, with the latter being more efficient. Further analysis of biological samples will test for variation in effects among taxa. Despite the apparent reduction in coastal organisms through exchange, a small percentage (but sometimes still a large number) of residual organisms can remain in exchanged tanks. The overall effect of ballast water exchange in reducing invasions therefore depends not only upon (a) the percent of vessels that exchange their ballast water and (b) the methods and results of exchange per vessel, but also (c) the relationship between supply and invasion rates. Although reduced inoculation densities should result in reduced invasion rates, the shape of this relationship is unknown. Thus, efficacy of exchange, or other management strategies, must be measured according to both rate of organism transfer and rate of invasion.
Author to Contact: M. Frey
Smithsonian Environmental Research Center
P.O. Box 28
Edgewater, MD 21037 USA
T 301-261-4190
F 301-261-7546
Key Words: economic impacts of invasions, Red Sea, Mediterranean, fisheries, prawns, jellyfish
Invasions by allochthnous species occur in aquatic ecosystems throughout the world, leading to significant, and sometimes severe, biological repercussions and economic effects. The opening of the Suez Canal initiated a remarkable faunal movement: hundreds of Red Sea species settled in the Mediterranean, forming thriving populations along the Levantine coasts.
Huge swarms of the invading nomadic jellyfish, Rhopilema nomadica, have appeared each summer along the southeastern Levant coast since the mid 1980's, and by 1995, reached the southeastern coast of Turkey and Cyprus. The massive swarms of these planktotrophs must play havoc with the meager resources of this oligotrophic sea, and when the shoals draw nearer shore, they impact fisheries, coastal installations and tourism. That same jellyfish shelters among its tentacles, the juveniles of a Red Sea carangid fish Alepes djedaba, an increasingly important catch.
Other abundant invaders are exploited commercially, constituting today nearly half of the trawl catches along the coast of Israel. Some commercially important invaders have outcompeted authochtonous species. A native penaeid prawn, Penaeus kerathurus, that supported a commercial fishery throughout the 1950's, has since nearly disappeared and its habitat overrun by the Red Sea penaeid prawns Penaeus japonicus and P. semisulcatus. From the southern coast of Turkey to Tunis, Red Sea penaeids have replaced P. kerathurus in prawn fisheries.
Though the expected outcome of invasion is reduction in diversity, we witness an invasion that increases diversity and has added new species to the local fisheries.
Author to Contact: Bella Galil
National Institute of Oceanography
Israel Oceanographic and Limnological Research (IOLR)
P.O.Box 8030
Haifa 31080
Israel
Email: galil@math.tau.ac.il
Key Words: Sargassum muticum, epiphytic communities, invasive seaweed, species diversity
Sargassum muticum was introduced to the West Coast of the United States in the 1940ís and has since established itself as a persistent member of coastal communities from British Columbia to California. The efficient dispersal methods and fast growth of S. muticum allow it to effectively compete for space and light with native seaweeds. S. muticum reaches up to 3.5 m, forming large "trees" due to its extensive branching and buoyancy provided by floats. This study investigated the epiphytic communities associated with S. muticum to determine if the seaweedís presence affects the composition of shallow subtidal communities in northern Puget Sound.
The community that S. muticum supports differs from that associated with the native seaweed Laminaria saccharina, the seaweed most often displaced by the invading S. muticum. The S. muticum species community composition is dominated by five snails, one polychaete, four crabs, four caprellids, several other amphipods, two isopods, and two shrimp. The L. saccharina species community composition is dominated by one bryozoan, one scaleworm, and a variety of larger snails. Several species of polychaetes, bryozoans, and nudibranches associated with L. saccharina were never found associated with S. muticum. Unlike the seasonally stable community associated with L. saccharina, the community associated with S. muticum changes throughout the growing season (May through October), and with the local habitat. Individual S. muticum thalli also support more epiphytic biomass per gram of algal tissue than do L. saccharina thalli. The concentration of detritus and diatoms on the extensive thallus is then available to browsers. S. muticum is also a primary food source for grazers, including the snails, Lacuna vincta and L. variegata. The seaweed provides a refuge for several fish species and juveniles of both the red rock crab and the dungeness crab. In summary, the invasion of S. muticum changes the ecology of the coastal communities by allowing certain native species to dominate over others that are associated with the native L. saccharina.
Author: Karen Giver
Biology Department, Western Washington University
Bellingham, WA 98225-9160
T (360) 885-2797
F (360) 650-3148
Key Words: ballast water sediments, hull fouling
Hawaii's status as a net importer of manufactured and raw materials tends to decrease the average amount of ballast water carried by commercial vessels arriving to ports in the area. Alternate vectors such as ballast water sediments and hull fouling can be of more importance in a port system with this operational dynamic. Ballast water sediments and hull fouling organisms are being collected randomly from commercial vessels arriving in Hawaii from foreign and U. S. mainland ports. Live analysis of all samples is performed and the ballast water sediments are further examined by culture methods to assay for phytoplankton species. Hull fouling samples and ballast sediments have yielded live, viable organisms like the barnacle Chthamalus proteus, which has been introduced into Hawaii. The findings to date for this study and historical data on hull fouling species reported in Hawaii will be presented.
Author to Contact: Scott Godwin
Bishop Museum
Department of Natural Science
1525 Bernice St.
Honolulu, HI 96817-0916
T 808-848-4156
F 808-847-8252
Key Words: ballast water, sampling methods, survival rates, international co-operation
During the last decades ballast water discharges have increased throughout the world in most of the major ports. Discharge volumes are considerably higher in some areas and the probability of successful establishment of self-sustaining populations of exotic species is expected to increase with greater volumes of ballast water and reduced ship transit times. Ships have been recognized as a major vector for the introduction of nonindigenous and harmful organisms. Although many desk studies and ship sampling programs were carried out it is agreed that a lack of data on the survival rates during ship journeys exists. Sampling of vessels during voyages were carried out on a limited scale by several laboratories. Detailed formation on changing environmental conditions in ballast tanks and on the survival rate of species will assist to evaluate the risks of unintentional species introductions in the future. During a previous study, the survival of plankton organisms in ballast water tanks was studied by accompanying a container vessel on its 23 day voyage from Asia (Singapore) to Germany (Bremerhaven). Former ballast water investigations during ship journeys showed the decrease of specimens and the reduction of diversity according to the time of the ships voyage. As expected, the number of specimens decreased dramatically in one of the two investigated tanks. In the second tank the number of individuals of the harpacticoid copepod, Tisbe graciloides, increased from 11 specimens per 100 litre in the beginning to more than 1000 individuals in the end. An increase of specimens during ship journeys was never documented before. This new dimension of species transportation in ships ballast tanks indicates that ballast tanks may be incubators under special conditions and emphasises the risk of species transport with this vector. In the beginning of 1998, a Concerted Action Study, financed by the European Union, was launched dealing with e.g. the harmonisation of sampling methods of ballast water and documentation of survival rates of species during inter-oceanic and short term voyages. Various European sampling methods have been studied in order to assess their effectiveness qualitatively and quantitatively. First results showed that the effectiveness of these ballast water sampling methods varied from 95,8% to less than 5%. Furthermore, sea-going workshops will involve Concerted Action Partners and invited experts on a broad scale. In total 6 voyages quantifying the survival of organisms in ballast tanks will be undertaken. The applicability of the harmonised ballast water sampling method will be addressed on board. The initial results of two intercalibration workshops of ballast water sampling methods and two ocean-going workshops are discussed.
Contact: Stephan Gollasch
Institut fuer Meereskunde
Duesternbrooker Weg 20
20146 Kiel
Germany
T ++49-431-597-3916
F ++49-40-360-309-4767
Email: sgollasch@aol.com
Key Words: marine worms, aquatic nuisance species, pathways, Puget Sound, Washington, risk assessment
The shipment of marine bait worms from Maine for recreational purposes-a likely pathway for NIS introductions in other Pacific coast estuaries (Carlton, 1989; Cohen et al.,1995) is not presently regulated in Washington State. In order to assess the risk of NIS introductions to Puget Sound, Washington through this pathway, we surveyed users of the product and product suppliers. The surveys consisted of telephone interviews, visits to local live bait worm vendors and product inspection. We found no evidence that live marine bait worms were available through local vendors or of a local market for live marine bait worms. Therefore, we determined that the live bait worm trade does not appear to pose a threat to the Puget Sound region.
References
Carlton, J.T. 1989. Manís role in changing the face of the ocean: biological invasions and implications for conservation of near shore environments. Conservation Biology, 3(3):265-273.
Cohen, A.N., J.T. Carlton, and M.C. Fountain. 1995. Introduction, dispersal, and potential impacts of the green crab Carcinus maenas in San Francisco Bay, California. Marine Biology, 122:225-237.
Author to Contact: Jessica Gramling
School of Marine Affairs
University of Washington
3707 Brooklyn Avenue NE
Seattle, WA 98105-6715
Phone: (206)685-3270
Fax: (206)543-1417
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