The kelp Undaria pinnatifida (Harvey) Suringar (Laminariales, Phaeophyceae), a native of Japan, northern China, and Korea, is now established at multiple locations throughout the world, including the west coast of the United States and Mexico. In 2000, U. pinnatifida was first reported in the United States from Los Angeles Harbor, California. Within a year, it had also been found 500 km to the north, in Monterey Harbor, California. In 2002, this alga was reported from Ensenada, Mexico to Monterey, California, and no subsequent spread has been reported since this time. In May 2009, we discovered U. pinnatifida to the north, at two marinas in San Francisco Bay and the outer coastal harbor at Pillar Point, San Mateo County. All observed individuals were removed and measured. Based on size and reproductive status, it appears that multiple cohorts were present. Transfer on the hulls of recreational boats is suggested as the source of this recent range expansion in California. Given the large flux of both recreational and commercial boat traffic in San Francisco Bay, this may become an important source for further spread both along the coast and to other biogeographic regions.

The Tuxpam and Tecolutla rivers in the Gulf of Mexico, are located in the Mesoamerican biodiversity hotspot and support different human activities: crude oil extraction, agriculture and livestock, that provoke environmental disturbances. Aquatic mollusks, physicochemical water characteristics and substrate type were examined along the main watercourse of these rivers during three periods of one year: the wet season, dry season, and during the northern winds season, when hurricanes are more frequent. In both rivers, physicochemical water characteristics, types of substratum and mollusk fauna demonstrated environmental gradients and differentiate two river zones: freshwater and estuarine. Differences were also found between the dry season, with higher inorganic salts content, and the wet and northern winds and hurricane seasons, when inorganic and organic nutrient inputs occurred. The mollusk fauna is composed of nine and eleven taxa in the Tecolutla and Tuxpam rivers, respectively. In both rivers, the introduced gastropod Tarebia granifera is the dominant species in the freshwater zone with regard to population density and the area it covers within the ecosystem, followed by the introduced bivalve Corbicula fluminea. Native mollusk species were confined to point-locations and attained very low densities. The gastropod Neritina virginea and the bivalve Brachidontes exustus were dominant in the estuarine zone of both rivers. Mollusk population densities declined during the wet, northern winds and hurricane seasons, while in the dry season both alien species reached higher densities, which could indicate that alien mollusks are removed by effect of climatic events. T. granifera and C. fluminea exhibit traits characteristic of invasive species and pose a risk to native mollusk biodiversity in these rivers.

Nowadays, invasions of invertebrate species in coastal ecosystems have become an ineluctable and irreversible phenomenon. The recent introduction of two western pacific crustacean decapods—the Asian shore crab, Hemigrapsus sanguineus, and the brushclawed shore crab, Hemigrapsus takanoi — along the French coast has revealed the problematic effects that invasive species can have on biodiversity and also the competition that invasive species represent for native crab species. This study describes the distribution and abundance of both Hemigrapsus species along the Opal coast on the French side of the Dover Strait in spring 2008. Both species occupy habitats similar to that of the green crab, Carcinus maenas. However, the habitats colonised by the two species are clearly segregated: low hydrodynamic muddy habitats for H. takanoi and high hydrodynamic habitats with fine and medium sands for H. sanguineus. Both species can live in sympatry in harbours. In spring 2008, the maximum density outside Dunkirk harbour was 12 ind.m^-2 for H. sanguineus, and inside Dunkirk harbour, the maximum density was 60 ind.m^-2 for H. takanoi. In this location, H. takanoi dominated C. maenas significantly. No ovigerous females of either invasive species were found during the spring. Both species have high colonisation potential, ranging from south of the Bay of Biscay to Germany for H. takanoi and from the western part of the English Channel to Germany for H. sanguineus.

The occurrence of the invasive Asian shore crab Hemigrapsus sanguineus (de Haan, 1835), around the Cotentin Peninsular, Normandy, France, is reported. The northern and eastern Cotentin coasts are more densely colonised (maximum density ≅ 10 ind.m^-2) than western shore, where the crab remains rare. These colonisation and establishment demonstrate probably the western progression of the species from its initial introduction into the Le Havre harbour during 1999.

The Indo-Pacific lionfishes (Pterois volitans [Linnaeus 1758] and P. miles [Bennett 1828]: Family Scorpaenidae) are the first non-native marine fishes to establish in the Western North Atlantic. The chronology of the invasion is reported here using records from the US Geological Survey’s Nonindigenous Aquatic Species database. Currently, lionfish are established off the Atlantic coast of the USA from the Florida Keys to Cape Hatteras (North Carolina), the Great Antilles, Bermuda, Bahamas, Cayman Islands and Turks and Caicos. The species have been reported from only one island in the Lesser Antilles (St. Croix), but it is not yet established there. Lionfish are established in Mexico, Honduras and Costa Rica. Reports have come from the Gulf of Mexico (Florida), Belize, Panamá and Columbia; although lionfish are not considered established in these localities at this time (August 2009), invasion is likely imminent.

A shoal of the Australian spotted jellyfish, Phyllorhiza punctata, native to the southwestern Pacific, was spotted on July 27, 2009 off the Mediterranean coast of Israel. Several recent records suggest that the vessel-transported species may have established a reproducing population.

A single specimen of Asterias rubens was collected on 17 February 2009 off Karasu, Sakarya, Turkey. Its possible impact on Mytilus galloprovincialis beds in the Black Sea is discussed.

The present work reports the finding of an exotic and invasive annelid, Branchiura sowerbyi Beddard, 1892, in freshwaters of São Miguel Island – Azores archipelago (Atlantic Ocean). One specimen was found near the mouth of Ribeira Quente stream in the south of São Miguel on 7 May 2008. This study increases the number of freshwater Oligochaeta species occurring in the Azores from 8 to 9.

This paper presents a short review of published data and the authors’ own observations related to the occurrence of the parasitic worm Aspidogaster conchicola (Baer 1827) in the Chinese pond mussel Sinanodonta woodiana (Lea 1834). Infections were found in some fresh-water bodies in Poland (Konin Lakes System) and Ukraine (Danube Basin). The prevalence of infection ranged from 5 to 30%, intensity of infection – 1-2 specimens/mollusk. Free-living species of ciliates, nematodes and chironomides were also discovered during the investigation of S. woodiana in the Konin Lakes System (Poland).

Between 2006 and 2009, we surveyed marine fouling communities across 81 subtidal sites, and sampled hulls and sea-chests from 18 domestically operated commercial vessels. Caprella mutica was present at 33% of the sites and on 22% of the vessels, sometimes at remarkably high densities (>10,000 individuals m^-2). Our findings confirm an extensive distribution of C. mutica along the coast of the northeast Pacific, and offer additional evidence in support of hull fouling as an important vector for secondary spread.

The cnidarian Blackfordia virginica and the adult of the caridean prawn, Palaemon macrodactylus are first recorded from the Guadiana Estuary. The habitats and environmental conditions under which these species were found are described and the potential impacts and mitigation measures for their introduction are discussed. The first observations of adults of these species were made in July 2008, at the transitional zone of the estuary (brackish area). Most samples taken in the middle-estuary were characterized by large densities of B. virginica (> 100 individuals 100 m^-3), while P. macrodactylus was recorded in much smaller densities (<0.01 individuals m^-2). Despite a comprehensive survey of invertebrates done between 1999 and 2003, neither of these species was previously detected in the Guadiana estuary. These observations may, therefore, coincide with the introduction of these species to the Guadiana estuary. Small planktonic crustaceans are generally described as the main food items for B. virginica. Our results show that the presence of the medusa was usually associated with a reduction of densities of all zooplanktonic organisms, including eggs of Engraulis encrasicolus. The reduction of planktonic biomass could have severe implications for organisms at upper trophic levels, such as E. encrasicolus, which use the Guadiana estuary as a nursery area and feed mostly on small planktonic crustaceans. Moreover, the potential consumption of eggs by B. virginica could potentially increase the impact on the nursery function of the estuary. The other alien species detected, P. macrodactylus, appears to be a strong invader, able to colonise a wide geographical range. It has a strong osmoregulatory capacity, and is known to inhabit a wide range of salinities, particularly if compared to similar native species (Crangon crangon and Palaemon longirostris). There is clear potential for the occurrence of competition for food between P. macrodactylus and the native prawn, due to dietary overlapping. The Guadiana estuary is under Mediterranean climate influence and is expected to be strongly impacted by climatic changes in the next decades. Other threat-factors are also present, such as increasing regulation by dams, the construction of new harbors, and increase shipping activity. It is important, therefore, to study the impact of these new invasions in this estuary and, based on the ecohydrology approach, propose mitigations measures to be applied in this system and other similar ecosystems worldwide.

Here, we record the presence of the invasive Indo-Pacific lionfish (Pterois volitans) in Colombia based on six individuals collected in the Parque Nacional Natural Tayrona, Santa Marta (southern Caribbean), as well as two individuals observed in San Andres Island (western Caribbean) during May-July 2009. This is the first report of lionfish from South America.

Non-native suckermouth armored catfishes (Loricariidae) of the genus Pterygoplichthys are now common throughout much of peninsular Florida. In this paper, we present preliminary observations on interactions between a Pterygoplichthys species, tentatively identified as P. disjunctivus (Weber, 1991), and endangered native Florida manatees, Trichechus manatus latirostris (Harlan, 1824), in artesian spring systems in Florida’s St. Johns River drainage. The introduced catfish have become abundant in spring habitats, sites used by manatees as winter thermal refuges. In the spring runs, Pterygoplichthys regularly attaches to manatees and grazes the epibiota on their skin. On occasion, dozens of Pterygoplichthys congregate on individual manatees. Manatee responses varied widely; some did not react visibly to attached catfish whereas others appeared agitated and attempted to dislodge the fish. The costs and/or benefits of this interaction to manatees remain unclear.

The worldwide transfer and introduction of non-indigenous invasive aquatic organisms via ships’ ballast water has been amply demonstrated to cause significant ecological, economic and human health impacts. Possible solutions to the problem include: 1) treating ballast water to remove or destroy unwanted organisms; 2) re-designing new vessels to eliminate the need to discharge ballast water; and 3) retaining ballast water onboard. Ballast water exchange is currently the only widely acceptable and suggested (sometimes even required) procedure to minimise the risk of ballast water mediated invasions but the variable efficacy and operational limitations of this approach have led to significant financial investment in the last two decades in the research and development of more effective shipboard and shore based ballast water treatment technologies. Specific technologies under consideration include mechanical separation, heat treatment, UV irradiation, cavitation, de-oxygenation and active substances. To date, no single treatment option has proved to be universally effective and increasing attention has focused on multicomponent treatment systems. The high flow rates and volumes of ballast water that must be treated pose significant technological challenges, and the presence of sediment in ballast tanks reduces the efficacy of many treatment options as this provides a habitat for resistant organisms such as resting stages of phytoplankton and zooplankton. Mechanical separation devices would best be used as a primary stage of a treatment system comprising multiple technologies because free-living organisms and sediment below a certain size are likely to be largely unaffected. UV treatment systems are unlikely to eliminate all ballast water organisms, as they are not able to deliver a stable lethal dose across a wide range of water quality conditions and many organisms are resistant to UV exposure or can recuperate after treatment. At the current stage of development, cavitation would not be considered appropriate for the shipboard treatment of ballast water due to high capital and operating costs and high power requirements. The heating of ballast water using waste heat from ships’ engines has been claimed to be a practical and cost effective treatment options for eliminating ballast water zooplankton and phytoplankton (including resting stages) but concerns have been expressed that attainable temperatures may not eliminate all bacterial pathogens, that this approach does not apply to ships traversing colder seas and may impact on the integrity of vessel structures. Promising research has been conducted on several systems that are able to achieve temperatures capable of eliminating bacteria but these technologies are still under development. De-oxygenation by the addition of glucose or reducing agents are not effective treatment options, however deoxygenation technologies based on the injection of an inert gas are more promising (notably against larval and adult zooplankton) as they could be cost effective and do not impact on the aquatic environment as ballast water is re-oxygenated prior to discharge. Biocide dosing systems have low capital costs and power requirements but the costs of active substances are significant. Chemical treatment costs and space requirements can be significantly reduced by using onboard chemical generators but the capital cost of these systems is significant and all have biological efficacy, safety, operational and environmental (poor biodegradation) concerns. Treatment systems that produce free hydroxyl radicals would be favourable over other chemical treatments as they are claimed to produce less or no toxic by-products at ballast discharge but these technologies have high power requirements. Each treatment option requires further research on their biological and operational efficacy and safety under full-scale shipboard conditions. As of July 2009, 16 promising systems using active substances had received basic approval and 8 systems final approval from IMO, with 4 systems receiving type approval certification and 2 systems receiving national approval certification. Effectively eliminating the risk of ballast water mediated invasions still remains a monumental technological and economical challenge.