Key words: Codium fragile, kelp canopy, competition

The green alga Codium fragile ssp. tomentosoides (Chlorophyta, Codiaceae), a potent biological invader native to Japan, has colonised coastal areas around the world, including NW Europe, the Mediterranean, New Zealand and North America. While the species meets the criteria of a successful invader in all of these invaded regions (establishment, population expansion and dispersal), the degree to which it develops into a pest species varies significantly among regions: in the NE Atlantic Ocean (Northern Europe), Codium has a wide distribution but is limited to small individuals (20 - 30cm) occurring in small populations within the low intertidal zone. In contrast, in the NW Atlantic Ocean (New England and Nova Scotia, Canada) Codium is locally abundant in intertidal pools, but is especially dominant in the shallow subtidal zone, where plants grow to 1m in length and form continuous meadows, often replacing entire kelp beds (Chapman, 1999; Scheibling, unpubl. data). Indirect evidence (loc. cit.) suggests that Codium spread in rocky subtidal areas off Nova Scotia is facilitated by the removal of kelp canopy which might otherwise competitively exclude the invader. In a system which naturally oscillates between two states - kelp beds and 'barrens' dominated by crustose coralline seaweeds (Johnson & Mann, 1988) - the temporary simultaneous absence of potentially effective urchin grazers (Strongylocentrotus droebachiensis) and kelp competitors might provide Codium with the necessary 'invasion window' to develop large populations. Where such 'windows of opportunity' do not exist or where the species pool of potentially limiting competitors is much larger in the first place (as is the case in the NE Atlantic), Codium population densities might remain under control (Chapman, 1999).
In order to test the effects of potential competitors on Codium in the subtidal zone, we measured performance (survival and growth) of transplanted Codium in relation to two experimental factors in the field. We manipulated kelp(canopy effects) and turf (understorey effects), at each of two levels - presence or absence. Development of individual Codium plants was recorded over 20 months.
Within the first year of the experiment, simultaneous kelp presence and turf absence prompted highest survival rates of Codium plants. Subsequently, significant differences in Codium survival among experimental treatments disappeared until after 14 months, the absence of turf was correlated with highest Codium survival. Length measurements of Codium revealed that the main growing periods were in the fall spring. Individuals were able to perennate as microscopic filaments, especially throughout the winter.
Our results do not support the hypothesis that a kelp canopy impairs survival or growth of already established adult Codium fragile ssp. tomentosoides. Alternatively, we suggest that kelps interfere with reproductive stages of the invader during settlement or establishment.

References:
Chapman, A. S. 1999: From introduced species to invader: what determines the success of Codium fragile ssp. tomentosoides (Chlorophyta) in the North Atlantic Ocean? Helgoländer Meeresunters. 52: 277-289.

Johnson, C. R. & Mann, K. H. 1988: Diversity, patterns of adaptation, and stability of Nova Scotian kelp beds. Ecol. Monogr. 58: 129-154.

Author to contact: Annelise S Chapman, Anthony R Chapman and John Lindley
Dalhousie University, Biology Department
Halifax, Nova Scotia B3H 4J1, Canada
Tel: 1-902-494-2349
Fax: 1-902-494-3736
email: aalbrech@is.dal.ca

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Keywords: Ballast water, invasion rate, database

As a national center, SERC's Marine Invasion Research Laboratory provides synthesis, analysis, and interpretation of invasion-related patterns for the country. Under the National Invasive Species Act of 1996, the U.S. Coast Guard and SERC created the National Ballast Water Information Clearinghouse to collect and analyze national data relevant to coastal marine invasions. Established at SERC in 1997, the Clearinghouse measures:

· Nationwide Patterns of Ballast Water Delivery and Management. All commercial ships arriving to all U.S. ports from overseas report information about the quantity, origin, possible control measures for their ballast water - a primary mechanism for transfer of non-native marine species throughout the world. At present, SERC receives roughly 20,000 such reports per year. Every two years, SERC provides a detailed analysis and report to U.S. Coast Guard and Congress on the patterns of ballast water delivery by coastal state, vessel type, port of origin, and season. A key issue is the extent to which ships undertake ballast water exchange, a management technique to flush potential invaders out of the tanks prior to arrival in U.S. waters. SERC's analysis is used by U.S. Coast Guard and Congress to assess national needs with respect to ballast water management.

· Rates and Patterns of U.S. Coastal Invasions. SERC has developed and maintains a national database of marine and estuarine invasions to assess patterns of invasion in space and time. This database compiles a detailed invasion history of approximately 500 different species of plants, fish, invertebrates, and algae that have invaded coastal states of the North America. Among multiple uses, the database identifies which species are invading, as well as when, where, and how they invaded; it also summarizes any existing information on the ecological and economic impacts of each invader. Over the long-term, this database will help assess the effectiveness of various management strategies (such as ballast water management, above) in reducing the rate of invasions. More broadly, this information is a valuable resource for many user groups --- from resource managers and scientists to policy-makers and industry groups.

Selected results from the first 18 months of data collection are presented and illustrate what has been learned about commercial shipping patterns and ballast water delivery and management in the United States. Excerpts from SERC's national invasion database illustrate important patterns of invasion in marine and estuarine waters of the United States.

Authors to contact: Esther Collinetti, Whitman Miller
Smithsonian Environmental Research Center
647 Contees Wharf Road
Edgewater, MD 21037
Phone: 443-482-2200
Fax: 443-482-2380
Email: Collinetti@serc.si.edu

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The Need for a Plan
Marine invasives are entering coastal and estuarine waters at an unprecedented rate largely by human-mediated pathways. While many human activities that affect invasives, such as ballast water exchange, are best addressed through regulation and coordination with industry, other pathways are under the control of individual users. These target groups are best reached through education and outreach efforts. At the same time there is a need to better understand the relative risks that each established or incipient non-native marine species might pose.

The State of Washington developed a draft ANS plan in accordance with National ANS Task Force guidelines in 1998. A significant enhancement to that plan took place in 2000. Under the leadership of WSGP, the subcommittee on Education, Research and Risk Assessment prepared sections of the plan that addressed the need for better public awareness and further scientific enquiry.

Process for Developing a Plan
WSGP developed an innovative process for engaging stakeholders and working through the subcommittee on Education, Research and Risk Assessment. We consulted with user groups who have the potential to introduce and spread marine invasive species, as well as groups most likely to be strongly affected by marine invaders. The process for plan development also included key state legislators and built on existing relationships and ANS planning processes, including cooperation with the Province of British Columbia, Canada. Public educators, university faculty, marine researchers, representatives of the boating community, public aquaria and natural resource managers helped shape the program. The process focused around pathways for introduction, risks of establishment and introduction, target audiences, educational vehicles and important messages.

Setting Priorities for Action
There will never be enough dollars to meet the challenge for all marine invasives; it is important to set priorities, based on the relative risks posed by each pathway, species of concern, and target audience. We have developed criteria to weigh the risks and set priorities among the many possible activities and projects that are under consideration in Washington State. These criteria weigh the potential risk of individual species and pathways; they look at the relative costs and benefits for immediate and longer-term action; and they encourage the development of strategic partnerships.

We will present the criteria we have used for setting priorities and will use examples to demonstrate the critical path for choosing education and research activities of importance to Washington State and the Pacific Northwest. Some of these activities are part of the state's ongoing program, including education, monitoring and research on the European green crab. Others are just starting, such as outreach to the dive and recreational boating community and research on competitive advantages among native and non-native clams in marine protected areas. A number of activities are still under consideration; we will use several to demonstrate the effectiveness of the system.

Author to contact:  Andrea E. Copping
Washington Sea Grant Program
University of Washington
3716 Brooklyn Ave NE, Seattle, WA 98105
tel: 206/685-8209
fax: 206/685-0380
Email: acopping@u.washington.edu

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Keywords: Salinity tolerant tilapia; tilapiinae; Salton Sea; Gulf of California; Gulf of Mexico

Establishment of exotic fish species has been reported to result from escape from government-led biological control projects, from the aquarist industry, and from aquaculture. Cichlid fishes of the subfamily tilapiinae from Africa (Trewavas 1983) are among the world's most widely distributed exotic fishes. Tilapiine fishes have established in nearly all tropical and sub-tropical freshwater ecosystems to which they have had access. To date, however, invasions of tilapiine fishes have been considered a problem only for the world's freshwater ecosystems. We present data from the USA and review reports from workers worldwide which demonstrate that saline-tolerant tilapiine fishes have established worldwide in estuarine ecosystems to which they have gained access and have the potential to penetrate warm temperate estuaries where thermal refugia exist. We contend that saline-tolerant tilapiine fishes constitute a major threat to the fish communities of the world's estuaries.

One of the most widely distributed exotic fish species is the Mozambique tilapia, Oreochromis mossambicus, which was exported worldwide first for the control of aquatic nuisance species (mosquitoes and aquatic vegetation); then for pond aquaculture. O. mossambicus, although stenothermal, is euryhaline. Lower lethal water temperature has been reported at 9.5oC. Lethal water temperatures for other tilapiine fishes are: 6.2oC (O. aureus); 10.3oC (Sarotherodon melanotheron); and 11.2oC (Tilapia mariae). Jennings and Williams (1992) reported S. melanotheron reproducing in at oceanic salinities (33-35 ppt) and able to survive hypersaline (100 ppt) conditions. Costa-Pierce and Riedel (2000) reported an O. mossambicus hybrid actively reproducing in salinities >45 ppt in the Salton Sea, California, USA, where they comprise over 50% of the biomass and numbers of the fish community.

Estuaries have been reported as the most anthropogenically degraded habitat type on Earth. Saline-tolerant tilapiine fishes are reported as part of fish communities in estuaries in Australia, Southeast Asia, the Pacific, and the Americas. Two reasons for their success are their high tolerances of poor water quality and disease. In addition, tilapiine fishes have an unusual mouthbrooding behavior and remarkable abilities to migrate long distances with broods, thereby impacting areas far from the source(s) of introduction and spawning. S. melanotheron in Africa occupy habitats rich in aquatic vegetation and organic matter in coastal lagoons and estuaries. Faunce and Paperno (1999) reported S. melanotheron were 90% of the biomass in an east-central Florida mangrove habitat. Costa-Pierce and Riedel (2000) reported that O. mossambicus in the Salton Sea, California, USA, a eutrophic saline lake, dominate the numbers and biomass of the fish community.

Impacts of tilapiine fishes on indigenous species may be through predation on native fish species, competition for food, and disease/parasite infestation. O. mossambicus predation on milkfish recruits had a major impact on Pacific atoll ecosystem. A large dietary overlap between O. aureus and shad larvae (Dorosoma spp) was observed in Texas and Florida. O. aureus has been observed to outcompete largemouth bass (Micropterus salmoides) for zooplankton depressing growth.

New reports of an advancing tilapia invasion into the estuarine reaches of the Barron and Mitchell Rivers in Queensland, Australia cause concern over the $150 million prawn and barramundi fisheries. The saline-tolerant and reproductively isolated O. mossambicus population in the Salton Sea, CA is of special concern to the lower Colorado River estuary and the Gulf of California, Mexico. The recent establishment of the tilapia in the Pascagoula River estuary in Mississippi, USA, could negatively impact the Gulf of Mexico sport and commercial fisheries, one of the most lucrative fisheries in the USA, especially if tilapia established in fish nursery habitats. Lastly, power plant warm water discharges could serve as important thermal refugia for saline-tolerant tilapia, thereby increasing the invasive potential of this group to temperate estuaries.

References

Costa-Pierce, B. and R. Riedel. 2000. Fisheries ecology of the tilapias in subtropical lakes of the United States, pp. 1-20. In B. A. Costa-Pierce and J. Rakocy (eds.) Tilapia Aquaculture in the Americas, Volume 2. The World Aquaculture Society, Baton Rouge, Louisiana, USA.
Faunce, C. and R. Paperno. 1999. Tilapia-dominated fish assemblages within an impounded mangrove ecosystem in east-central Florida. Wetlands 19:126-138.
Jennings, D. and J. Williams. 1992. Factors influencing the distribution of blackchin tilapia (Sarotherodon melanotheron) in the Indian River system, Florida. Northeast Gulf Science 12:111-117.
Trewavas, E. 1983. Tilapiine Fishes of the Genera Sarotherodon, Oreochromis and Danakilia. British Museum (Natural History), London, UK.

Author to contact: 
Barry A. Costa-Pierce
Mississippi-Alabama Sea Grant Consortium
703 East Beach Drive, Ocean Springs, MS 39564
Tel: 228-875-9368
Fax: 228-875-0528
Email: b.costapierce@usm.edu

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Accidentally introduced into the Mediterranean sea in 1984, the tropical alga Caulerpa taxifolia did not stop to spread since then. At the beginning of 2001, it was already present at least in 6 Mediterranean countries (Monaco, France, Italy, Spain, Croatia and Tunisia, by order of discovery). The ecological and economic threats related to this invasion incited scientists to organize national and international campaigns of sensitization, research and prevention in different Mediterranean countries.
Financed by local communities, national institutions and ministries as well as European Community programs, leaflets, posters or - recently - web sites, all conveyed the same message: "Wanted Caulerpa taxifolia. If you find this seaweed, do not help it to spread and phone us". They provide sea users with precise and updated information on the alga and his expansion. Practical advices invite people to get heavily involved in the control of C. taxifolia dissemination. Logos of institutional partners officialize the message and show that authorities are aware of the problem.

Since 1991, 190,000 leaflets and 25,000 posters were edited in 6 languages (French, Italian, Castilian, Catalan, Croatian and English) by our laboratory, and distributed in France, Italy, Spain and Croatia. Other hundreds of thousands leaflets were published and distributed by Tunisia and Turkey institutions, or by Non Governmental Organizations (100,000 by the Lions Club, in particular).

Divers, yachtsmen, fishermen, and port administrators are requested to warn scientists in charge of C. taxifolia about any new sighting of colonies. These campaigns enable the establishment and the consolidation of national and international informant networks which are crucial to the yearly assessment of C. taxifolia spreading in the Mediterranean sea and to the cartographic follow up of C. taxifolia invasion. More than 80 % of known C. taxifolia locations were reported by sea users.
Each sighting is verified by scientists. All communication campaigns conducted by our laboratory have been followed by "cartography reports" based on reported sightings. These allow to evaluate, every year (since 1990 in France), the characteristics of the progression of C. taxifolia in the Mediterranean sea.

To avoid any loss of information, only one organization (institution or laboratory) should be in charge of collecting new observations in each country. Only one phone number per country (or by large region) should be devoted to calls reception to ensure that all pertinent information is gathered.

The expansion of this invasive species is one of the main element to take into account in the evaluation of the global threat of this alga.
Although it is not possible to precisely evaluate the impact of these prevention campaigns, we may suppose that some sites have and will be probably preserved by the diffusion of thousands of prevention messages.

Author to contact: 
J.-M. COTTALORDA
Laboratoire Environnement Marin Littoral
Université de Nice-Sophia Antipolis, Faculté des Sciences,
Campus Valrose, 06108 Nice cedex 2, France
tel.: 0033492076845 - fax: 0033492076849
Mailto: cottalor@unice.fr
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Over the past two decades the importance of hull fouling as a major vector for the transfer of marine organisms to new locations has been overshadowed by the importance of ballast water. This has largely occurred due to the preconceived notion that hull fouling has been significantly reduced, if not eliminated, by significant improvements in antifouling paint technology, combined with an increase in vessel speeds and cargo loading times. Coutts (1999) concluded that while such improvements may have reduced the degree of fouling upon merchant vessels, there are still regions upon hulls that remain high-risk areas for the transportation of exotic marine organisms. One such region includes the inside dry docking support strips (InDDSS), which refers to those areas underneath large vessels where chocks are used during dry docking to support the vessel. Reapplication of new antifouling paint is precluded in such areas.

Coutts (ibid) also observed other regions of the hull with high levels of fouling. These were generally protected "nooks and crannies" or irregularities on the hull, which were commonly sheltered from harsh hydrodynamic forces (e.g. rudders, gratings, holes, etc). James and Hayden (2000) also recorded excessive fouling in protected areas upon vessels greater than 500 DWT. This study investigates the importance of protected areas on the hulls of merchant vessels as a mechanism for transferring exotic marine species, and compares these areas with other regions of the hull with respect to the level and diversity of fouling organisms.

In July 1999 a request was made to two commercial diving companies to view their archives of videos of underwater hull inspections of merchant vessels visiting New Zealand. A total of 30 vessels were randomly selected for the study and the video footage was viewed at Cawthron over the following two months. The vessels plyed international and domestic shipping routes and ranged in size from 2,300 to 30,000 DWT. The hull inspections were carried out during visits to one of three New Zealand ports: Auckland, Tauranga and Wellington, between 1998 and 1999. Lloyds surveying regulations ensured that the following regions of the hull were inspected: bulbous bows; bilge keels; InDDSS, Outside DDSS; seachest gratings; propellers; rudders; and rope guards. Video footage of the bow thruster region was restricted to two vessels only, therefore this region was excluded from quantitative analyses.

The percentage cover of fouling organisms within each region was determined by freeze-framing the video at various random locations and recording the taxa that occupied each of 50 random points. A cost-benefit analysis indicated that five quadrats provided sufficient replication for estimating the mean percentage cover of fouling taxa per hull region. Fouling organisms were classified according to three successional categories: category 1 - bare metal, painted surfaces, encrusting brown algae, encrusting green algae, filamentous green algae; category 2 - acorn barnacles, serpulids, coralline algae, encrusting bryozoans, hydroids; category 3 - solitary ascidians, compound ascidians, mussels and oysters (Figure 1).

The hulls of vessels with old (i.e. ineffective) antifouling paint were characterised by fouling organisms in successional categories 2 and 3. Conversely, vessels with new (i.e. effective) paint were characterised by organisms in successional category 1. As expected, the mean percentage cover of algal fouling was highest in the regions receiving the greatest amount of light such as on the bulbous bow, upper edges of the bilge keel, propeller, rudder and rope guards. Very little algae colonized the regions that receive the least amount of light, such as the Outside DDSS and seachest gratings. Coralline algae were very common on the propeller, where antifouling paint was absent. Although the InDDSS was often colonized by some coralline algae, insufficient light levels appeared to limit their success. Corallines were also found on the rope guards and sea chest gratings, but in these regions they were epiphytic.

In addition to algal fouling, the bulbous bow was dominated by compound ascidians, which was probably due to anchor chains removing the antifouling paint whilst the vessels were at anchor. Acorn barncales and sometimes mussels often colonized the sea chest gratings. The InDDSS were also dominated by acorn barnacles, and the rope guards were also sometimes colonized by mussels (Figure 1). The percentage cover of invertebrate taxa overall was highest on the InDDSS, rope guards and sea chests. These regions also had the highest richness of fouling taxa.

Figure 1. Percentage cover of fouling organisms on different parts of the hull within each of three successional categories, as determined by analyses of video footage taken for hull inspections of merchant vessels visiting New Zealand. Values are means ± 1. SE.
Interestingly, Coutts (ibid) found species richness, diversity and evenness amongst invertebrates to be highest on the InDDSS, which supports the findings from the present study. Coutts (ibid) found that 89 percent of the taxa that were present were found on the InDDSS, and 55 percent of the taxa were found only on the InDDSS. The InDDSS were also found to be colonized by three exotic species) yet to be introduced to Tasmanian waters: Megabalanus rosa, M. tintinnabulum, Balanus reticulatus and Watersipora arcuata.

This study has established that certain regions on the hulls of merchant vessels are more susceptible to fouling by exotic marine organisms than are others. The InDDDS, protected areas such as sea chest gratings and rope guards, and regions of the hull that are likely to have the antifouling paint removed by scraping (e.g. the bulbous bow), would appear to pose a higher risk than regions exposed to greater hydrodynamic forces. Targeting fouling surveys and management techniques at such regions might prove to be a cost-effective strategy for minimizing the rate of species transfers via hull fouling. Cawthron is following up the findings of this study with more research into the risks associated with the translocation of exotic marine organisms on vessels' hulls, and comparisons are being made between the significance of hull fouling and other shipping vectors such as ballast water.

References

Coutts, A.D.M. 1999. Hull fouling as a modern vector for marine biological invasions: investigation of merchant vessels visiting northern Tasmania. M. App. Sci. Thesis, Australian Maritime College, Launceston, Tasmania, Australia.

James, P. and Hayden, B. 2000. The potential for the introduction of exotic species by vessel hull fouling: a preliminary study. National Institute of Water and Atmospheric Research, Report June 2000.

Author to contact: 
Ashley D. M. Coutts
Biosecurity Scientist
Cawthron Institute
Private Bag 2, Nelson
New Zealand
Ph +64 3 548 2319
Fax +64 3 546 9464
Email: ashley@cawthron.org.nz

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Despite continued evidence of the negative impacts of introduced marine pests, little, if anything, is being done about already established invaders. Such is the case with the Chinese mitten crab, Eriocheir sinensis, which has extensively invaded the San Francisco Bay and associated watersheds. A catadramous species, it lives primarily in freshwater habitats until reaching maturity when it migrates to estuarine habitats to breed. With population estimates in the millions, this species now constitutes a substantial portion of the overall biomass in many freshwater areas. The high abundance of this crab has already caused great economic impacts on fish salvage operations of State and Federal water pumping facilities. Commercial fishermen have also experienced economic losses due to gear and product damage, and the need for additional labor and bait. Further, bank stability is threatened at several sites in the south bay due to the extensive burrowing activities of the mitten crabs. Ecological impacts, including predation of and competition with native species, have also likely occurred given the high abundance, distribution and habits of this crab. However, these impacts remain largely undocumented due to a lack of funding. Importantly, many threatened, endangered and commercially important marine and freshwater species are at risk. For example, mitten crabs have been documented in salmonid and steelhead spawning areas, potentially damaging these troubled populations through habitat destruction and predation on eggs and larvae.

Given the great economic and ecological impacts associated with this species, management strategies are needed. Prospective management techniques may include those that exploit specific migrations associated with the rather complex life cycle of this crab. For example, in order to reproduce adult crabs must migrate from freshwater areas to the bay. We have developed a passive trapping system specifically targeting capture of these migratory adults. This system was developed in collaboration with David Salsbery, Jae Abel and Lisa Porcella of the Santa Clara Valley Water District and involves modification of their existing salmonid monitoring system. Preliminary results are quite promising, as over 10,000 crabs were passively caught in approximately 6 weeks using 2 traps at one site. We will describe the system and the results from our pilot study. In addition, we will discuss the potential use of this system as a control method throughout the San Francisco Bay area.

Author to contact: 
Contact Person: Carolynn (Carrie) Culver
Marine Science Institute
University of California
Santa Barbara, CA 93106
Tel: (805) 893-8083
Fax: (805) 893-8062
Email: c_culver@lifesci.ucsb.edu

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Seven species of mangroves were introduced to the Hawaiian Islands from Florida in 1902 to stabilize the shoreline and provide forage for bees (Wester, 1981; Allen, 1998). At present in Hawaii, large portions of low-energy coastlines as well as the banks of streams and drainage channels are fringed by the red mangrove, Rhizophora mangle. R. mangle has high dispersal capabilities, broad tolerance, and few natural enemies in Hawaii (e.g., Allen, 1998; Cox and Allen, 1999; Steele et al., 1999); as a consequence, the mangrove habitat appears to be expanding rapidly in Hawaii. Prior to the very recent invasion of mangroves (and other exotic plant species), the intertidal zone of Hawaii lacked vascular plants (Wester, 1981). The introduction of vascular plants, particularly mangroves, to intertidal habitats can dramatically alter a variety of ecologically important characteristics. Mangrove root systems can provide cover from predators, potentially inhibiting top-down control of benthic community structure (cf. Peterson, 1979; Reise, 1985). In addition, mangrove roots extend the availability of solid substrate, providing attachment sites for encrusting fauna such as barnacles and bivalves (Shokita et al., 1989). The root structure of mangroves also baffles water flow, trapping fine and organic-rich sediments transported by currents or produced in situ from mangrove litter (Chapman and Ronaldson, 1958; Bird, 1971). Key environmental parameters altered by mangrove development typically include rates of water flow, sediment granulometry and organic-carbon content, oxygen and sulfide concentrations (both in bottom- and pore-waters), salinity and the availability of hard substrates (e.g., Alongi, 1987a; Robertson and Alongi, 1992). All of these factors can substantially influence the structure and dynamics of soft-sediment communities (see reviews by Pearson and Rosenberg, 1978; Robertson and Alongi, 1992).
In the only published study of the Hawaiian mangrove fauna, Walsh (1963, 1967) indicated that Hawaiian mangroves were a substantially under-utilized habitat. It is important to determine whether this "open niche space" has since been filled by introduced species and/or by native Hawaiian fauna increasingly able to colonize mangrove habitats. To evaluate the impacts of introduced mangroves on Hawaiian macrobenthic communities, we sampled sediments from mangroves and mudflats on the islands of Oahu and Molokai. In addition, we quantified epifauna and epibenthic structures on mangrove roots and the sediment surface using a 0.5 m2 quadrat. Infaunal macrobenthos in saltwater mangrove habitats in Asia, Australia and South America appear to be dominated by oligochaetes, polychaetes, amphipods and molluscs (e.g., Frith, 1977; Alongi and Christofferson, 1992; Lana et al., 1997). Our sampling from mangrove sediments in Kaneohe Bay and the South coast of Molokai, Hawaii, indicated a predominance of oligochaetes, polychaetes, and amphipods. Therefore, the macrofauna currently inhabiting Hawaiian mangroves appears to resemble that of native mangrove forests in other regions. In addition, mangrove roots provide a habitat for introduced species, including the barnacle Chthamalus proteus, tilapia (Oreochromis sp.) and the Samoan crab (Scylla serrata). The sampled mudflat community was dominated by polychaetes, primarily sabellids. Macrofauna in mangrove sediments were similar to those in mudflats at comparable tidal height, however we found greater infaunal species richness in mangrove sediment habitats. In conclusion, introduced Hawaiian mangroves appear to facilitate the establishment of opportunistic exotics, e.g., the Samoan crab and Chthamalus proteus, while concurrently enhancing local species richness.

References:

Allen, J.A.. 1998. Mangroves as alien species: the case of Hawaii. Global Ecology and
Biogeography Letters, 7:61-71.

Alongi, D.M. 1987a. Intertidal zonation and seasonality of meiobenthos in tropical mangrove
estuaries. Mar. Biol. 95:447-458.

Alongi, D.M. and P. Christoffersen. 1992. Benthic infauna and organism-sediment relations in a
shallow, tropical coastal area: influence of outwelled mangrove detritus and physical disturbance. Mar. Ecol. Progr. Ser. 81:229-245.

Bird, E.C.F. 1971. Mangroves as land-builders. Victorian Naturalist 88:189-197.

Chapman, V.J. and J.W. Ronaldson. 1958. The mangrove and salt marsh flats of the Auckland
Isthmus. New Zealand, Department of Scientific and Industrial Research, Bulletin 125, 75pp.

Frith, D.W. 1977. A preliminary list of macrofauna from a mangrove forest and adjacent
biotopes at Surin Island, western peninsular Thailand. Phuket Marine Biology Center
Research Bulletin 17:1-14.

Kay, E.A. 1987. Marine Ecosystems in the Hawaiian Islands. In: Reef and Shore Fauna of
Hawaii, Section 2:Platyhelminthes through Phoronida and Section 3: Sipuncula through
Annelida, ed. D.M. Devaney and L.G. Eldredge. Honolulu: Bishop Museum Press. p. 1-9.

Lana, P.C., E.C.G. Couto, and M.V. Almeida. 1997. Distribution and abundance of polychaetes
in mangroves of a subtropical estuary. Bulletin of Marine Science 60:616-617.

Pearson, T.H. and R. Rosenberg. 1978. Macrobenthic succession in relation to organic
enrichment and pollution in the marine environment. Oceanogr. and Mar. Biol. Ann. Rev.
16:229-311.

Peterson, C.H. 1979. Predation, competitive exclusion, and diversity in the soft-sediment
communities of estuaries and lagoons. In: Ecological processes in coastal and marine systems, ed. R.J. Livingston. New York: Plenum Press. p. 233-264.

Reise, K. 1985. Tidal Flat Ecology: An Experimental Approach to Species Interaction. Berlin:
Springer- Verlag. p.1-191.

Robertson, A.I. and D.M. Alongi, eds. 1992. Tropical Mangrove Ecosystems. Coastal and
Estuarine Studies. Washington: American Geophysical Union.

Shokita, S., J. Sanguansin, S. Nishijima, S. Soemodihardjo, A. Abdullah, M. He, R. Kasinathan,
and K. Okamoto. 1989. Distribution and abundance of benthic macrofauna in the Funaura
mangal of Iriomote Island, The Ryukyus. Galaxea 8:17-30.

Steele, O.C., K.C. Ewel, and G. Goldstein. 1999. The importance of propagule predation in a
forest of non-indigenous mangrove trees. Wetlands 19:705-708.

Walsh, G.E. 1963. An ecological study of the Heeia mangrove swamp. PhD dissertation,
Department of Zoology, University of Hawaii, Honolulu.

Walsh, G.E. 1967. An ecological study of a Hawaiian Mangrove Swamp. In: Estuaries, ed. G.H.
Lauff, pp. 420-431. Washington: AAAS.

Wester, L. 1981. Introduction and spread of mangroves in the Hawaiian Islands. Association of
Pacific Coast Geographers Yearbook 43:125-137.

Author to contact: 
Amanda W. J. Demopoulos (presenter)
University of Hawaii
Department of Oceanography
1000 Pope Road
Honolulu, HI 96822
Tel: (808) 956-8668
Fax: (808) 956-9516
Email: ajones@soest.hawaii.edu
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The economic and ecological threats posed by nonindigenous invertebrate species transported by ships' ballast water are much better documented and understood than the corresponding epidemiological threats posed by the introduction of nonindigenous microorganisms pathogenic to humans, plants, and animals. Current management strategies to limit new invasions associated with ballast water have principally employed at-sea ballast exchange, but this technique is not fully effective in washing out or killing organisms in tanks. It is generally considered that ballast exchange eventually will be complemented or even superceded by a more successful treatment(s). A variety of alternate treatments, including filtration, heating, and application of biocides, are currently being tested. In the case of microorganisms, however, filters can have limited success at best, heat may in fact promote growth of many microbial populations, and biocides may not inactivate resting stages, e.g., spores of bacteria and cysts of dinoflagellates.

Here we present photon-processing technology for the treatment of water in general, and ballast water in particular, with the ultimate intent of greatly reducing its concentration of protozoans, bacteria, and viruses. We have developed a highly efficient and cost-effective prototype reactor designed around a lamp that exposes aquatic microorganisms to germicidal wavelengths and quanta of UV light.

The lamp presents a large area with a cylindrical geometry, is RF-driven, and has a power density in the UV wavelengths of interest between 5 to 8 mW cm-2. To date, we have tested the reactor's killing efficacy on specific microorganisms (the bacteria Escherichia coli, Bacillus subtilis, and Salmonella typhimurium, and the dinoflagellate Gymnodinium catenatum) as well as on naturally occurring marine heterotrophic bacteria. We have determined three- to four log reductions in bacterial and dinoflagellate abundance, including spores and cysts, following as little as 30 to 60 second exposures to the UV light; longer exposures have resulted in up to a 7-log reduction, sometimes with no detectable bacteria remaining. We hypothesize that the intense UV lyses cells, as we observe a negative correlation between the optical density of the medium containing the microbes and time of exposure.

This research was supported in part by a grant from NOAA's National Sea Grant College Program

Author to contact: 
Fred C. Dobbs
Department of Ocean, Earth & Atmospheric Sciences
Old Dominion University
4600 Elkhorn Avenue
Norfolk, VA 23529, USA
(757)-683-5329 (phone) (757)-683-5303 (fax) fdobbs@odu.edu

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Our understanding of ballast-water biology is based to a large extent on studies of relatively large (>50 µm), metazoan organisms distributed across a variety of taxa, from polychaetes to copepods to fish. This state of affairs is not surprising, given that most of the public awareness and much of the scientific interest in ballast-water issues was instigated, in North America at least, by the appearance and proliferation of the zebra mussel, a metazoan dubbed by some the "poster child" of aquatic bioinvasions.

Even when microorganisms have been considered, the focus often has been on dinoflagellates, because some of these phytoplankton species have been implicated as players in harmful algal blooms. In contrast, microorganisms other than dinoflagellates have been little studied, yet there are good reasons to consider the invasion potential of other protozoans, bacteria, and viruses. These reasons include their abundance, metabolic diversity, life-history characteristics, range of physiological tolerance, and genetics.

I will discuss each of these above factors with regard to the diverse array of microorganisms in ballast water. When possible, I will present data from ballast-water studies, but insights often emanate from research outside that arena. I will conclude with an evaluation, from a microbial ecologist's perspective, of current and proposed methods for treating ballast water to reduce the risk of introducing nonindigenous species.

Author to contact: 
Fred C. Dobbs
Department of Ocean, Earth & Atmospheric Sciences
Old Dominion University
4600 Elkhorn Avenue
Norfolk, VA 23529, USA
(757)-683-5329 (phone) (757)-683-5303 (fax) fdobbs@odu.edu

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