So let us bond together for the greater good and work together. If we work together and each other does our part, we can make a huge difference. I hope that many people will join this important but relative rare idea of a volunteer citizen science monitoring network. Since we need to raise awareness and solve this important problem!
Invasive species are one of the greatest threats to marine biodiversity by reducing biodiversity and causing homogenization of our oceans (Tsutsui et al., 2000). Successful marine invaders such as the European Crab, Carcinus maenas, replace globally rare species with itself, a globally common species. Although this raises alpha-diversity in a site; more importantly, beta-diversity on a global scale is reduced. Bioinvasions are considered an important component of global change since they act on large scales and act synergistically with other environmental factors and problems (Vitousek et al., 1996). As a discipline, marine invasion ecology started in the 1970s and is still in its infancy. So far, only the transport vector and impacts are understood, but only some of the huge numbers of invaders have been accounted for, and even fewer marine bioinvasions have been comprehensively observed. The reason for the establishment of successful marine invasive species is still hotly debated and few answers have been agreed upon. Progress for marine ecology has been slow and minimal due to lack of quantitative data.
Invasive species have been documented to cause a decline in species density and richness that has led to major ecological impacts (Ebling et al., 1959). For example, C. maenas is responsible for the decline and collapse of species such as Katelysia scalerina,Mya arenaria, Cancer magister, as well as many other species, because this crab is a voracious omnivore and skilled competitor (Smith et al., 1955; Ropes, 1968; Walton et al.; MacDonald, 2000). Yet an important question for marine conservation biologists is “What are the characteristics of a successful global marine invader?”
Characteristics of a good invader: Based on the biology of Carcinus maenas
Determining general characteristics of successful marine invaders is important to understanding and preventing further marine bioinvasions, but the answer still remains an elusive challenge (Carleton 1996; Cohen et al. 1995). Yet scientists can study C. maenas, the most successful marine invader, to hopefully shed light on, and possibly understand the important biological characteristics of a good marine invader. This could help to identify strategies for recognizing potential future marine invaders and susceptibility of marine environments and areas to certain invaders. This could lead to better-informed policies and prioritizing monetary resources and time for the monumental problem of marine bioinvasions. Once an invasion occurs, eradication and control of the bioinvader is hard or impossible, so prevention is critical.
Carcinus maenas possesses important characteristics to not only enable it to be transported but also to thrive when it reaches new habitat. Firstly, C. maenas has a planktonic larval stage that allows it to be transported by the vector of ships’ ballast water (Carleton, 1987). Secondly, C. maenas is an excellent osmo-regulator, therefore it is a euryhaline species that can tolerate ranges of salinity from 35 down to 4 parts per thousand (Crothers, 1967). The crab can also withstand temperatures in the range of 22 to –1°C (Cohen et al., 1995). This allows C. maenas to inhabit a diverse range of marine ecosystems. Another important characteristic is that C. maenas is an omnivore and therefore food is usually not a limiting agent (Walne & Dean 1972; Lohrer et al., 2002). So by having the characteristics of a generalist, C. maenas can endure a wide range of environmental conditions, possibly explaining why the species has obtained its extensive global invasive range.
The main vectors for transporting marine invaders from their native to the invasive range, has been in the uptake and discharge of ballast water by shipping vessels and/or attachment or association with fouling organisms on the ships’ hulls (Grosholz and Ruiz 1996). Ballast water has been considered the primary vector for its dispersal (Carleton, 1989). This vector is the driving force that has allowed C. maenas to move from its native range of the Atlantic coast of Europe to an extensive introduced range that includes both coasts of North America, South Africa, Australia, and Tanzania (Crothers, 1967; Grosholz & Ruiz 1996). Although the transport vector of marine invaders has been studied and is understood, the mechanism for their establishment is a topic of great debate and divergence.
Salem Sound Coastwatch
For kids: Sea Grant Super Sleuth - Nab the Aquatic Invader!
This site does a great describing the ecology and range of the Asian shore crab (Hemigrapsus sanguineus). Also it details how to identify the organism.
The Washingston Dept of fisheries and Wildlife's site has a great webpage on the biology of European green crab, Carcinus maenas, and its history in Washington state.
An abstract that covers the history of the Asian shore crab (Hemigrapsus sanguineus) and trying to determine its density and impact.
This is a great scientific paper on the interaction between the invasive and native crab species.
This covers an overview of the green crab and does a great job going through the ecological and economic damages of the crab.
This site covers the great research of Dr. Nancy O'Connor and a good map of the Hemigrapsus invasive range around MA.
Sea Grant National Aquatic Nuisance Species Clearinghouse
MIT Sea Grant Center for Coastal Resources
Northeast Aquatic Nuisance Species Panel
Maine's Marine Invasion Forum
Smithsonian Institution Marine Invasions Research Lab
National Exotic Marine and Estuarine Species Information System
National Ballast Information Clearinghouse
Sea Grant Nonindigenous Species
Massachusetts Bays Program
The Global Invasive Species Database
Identify invasive organisms and key features
Northeast Aquatic Nuisance Species Panel
Hitchhikers at MIT Sea Grant
Noxious, Invasive, and Alien Plant Species
Maine Sea Grant: Invasive Species Checklist for Maine
Other Education Activities:
National Geographic Expeditions: Aquatic invaders
Publications by some of the experts on these 2 invaders:
Carlton, J. T. 1975. Extinct and endangered populations of the endemic mud snail Cerithidea californica in Northern California. Bulletin of the American Malacological Union. 41: 65–66.
Carlton J. T. 1985 Transoceanic and interoceanic dispersal of coastal marine organisms: the biology of ballast water. Oceanography Marine Biology Annual Review. 23: 313–374.
Carlton, J. T. 1987. Patterns of transoceanic marine biological invasions in the Pacific Ocean. Bulletin of Marine Science. 41: 452–465.
Carlton J. T. 1989 Man's role in changing the face of the ocean: biological invasions and implications for conservation of near-shore environments. Conservation Biology. 43: 265–273.
Carlton J. T., 1996. Pattern, process, and prediction in marine invasion ecology. Biological Conservation. 78: 97-106.
Carlton, J. T. & Gellar, J. B. 1993. Ecological roulette: the global transport of nonindigenous marine organisms. Science. 266: 78–82
Cohen A. N. & Carlton J. N. , 1998 Accelerating invasion rate in a highly invaded estuary. Science. 279: 555–558.
Cohen, A. N., Carleton, J. T., & Fountain, M. C. 1995. Introduction, dispersal, and potential impacts of the green crab Carcinus maenas in San Francisco Bay, California. Marine Biology. 122: 225-237.
Crothers, J. H., 1967. Biology of the shore crab Carcinus maenas. Amicus. 2: 407-434.
Elton, C. S. 1958. The Ecology of Invasions by Animals and Plants. London: Methuen and Company.
Grosholz, E.D. 1996. Contrasting Rates of Spread for Introduced Species for Introduced Species in Terrestrial and Marine Systems. Ecology. 77: 1680-1686.
Grosholz, E. 2002. Ecological and evolutionary consequences of coastal invasions. Trends in Ecology & Evolution. 17: 22-27.
Grosholz, E. D. & Ruiz, G. M. 1996. Predicting the impact of introduced marine species: lessons from the multiple invasions of the European green crab, Carcinus maenas. Biological Conservation. 78: 59-66.
Grosholz E. D., Ruiz G. M., Dean C.A., Shirley K.A., Maron J.L. & Connors P.G., 2000. The impacts of a nonindigenous marine predator in a California bay. Ecology. 81: 1206-1224.
Lohrer, A. M., Whitlatch, R. B., Wada, K., & Fukui, Y. 2000. Home and away: comparisons of resource utilization by marine species in native and invaded habitats. Biological Invasions. 2:41-57.
MacDonald, S. P., Jenson, G. C., Armstrong, D. A. 2001. The competitive and predatory impacts of the nonindigenous crab Carcinus maenas (L.) on early benthic phase Dungeness crab. Journal of Experimental Marine Biology and Ecology: 258: 39-54.
Ruiz, G. M., Carlton J. T., Grosholz E. D., & A.H. Hines, 1997.Global invasions of marine and estuarine habitats by non-indigenous species: mechanisms, extent, and consequences. American Zoologist. 37: 621-632.
Smith O. R., Baptist, J. P. & Chin. E. 1955. Experimental farming of the soft-shell clam, Mya arenaria, in Massachusetts, 1949-1953. Commercial Fisheries Review .17 6: 1-16.
Torchin, M. E., Lafferty, K. D., & Kuris, A. M. 2001. Release from Parasites as natural enemies: increased performances of a globally introduced marine crab. Biological Invasions. 3: 333-345.
Torchin, M. E., Lafferty, K. D., & Kuris, A. M. 2002. Parasites and marine invasions. Parasitology. 124:137-151.
Tsutsui, N.D., Suarez, A.V., Holway, D.A., Case, J.C. 2000. Reduced genetic variation and the success of an invasive species. Proceedings of the National Academy of Sciences of the United States of America 97 (11): 5948-5953.
Vitousek, P.M., D'Antonio, C.M., Loope, L.L., Westbrooks R. 1996. Biological Invasions as Global Environmental Change. American Scientist 84. pp. 468- 478.
Walne and Dean, 1972. P.R. Walne and G.J. Dean , Experiments on predation by the shore crab, Carcinus maenas L., on Mytilus and Mercenaria. Journal de Conseil International pour l'Exploration de la Mer. 34:190–199.
Walton, W. C., MacKinnonb, C., Rodriguez G. M., Proctor C., & Ruiz, G. M. 2002. Effect of an invasive crab upon a marine fishery: green crab, Carcinus maenas, predation upon a venerid clam, Katelysia scalarina, in Tasmania (Australia). Journal of Experimental Marine Biology and Ecology.