Carcinus maenas, commonly referred to as the European green crab, is a portunid crab native to northern European coastal waters. In the early 1800's, it appeared on the East Coast of the United States where it successfully extended its range as far north as Nova Scotia and as far south as Maryland. Later C. maenas successfully invaded the southern coast of mainland Australia, first reported in the early 1900's, and in 1993 colonized the island state of Tasmania. In 1989, the green crab appeared in San Francisco Bay and proceeded to invade coastal embayments to the north and south. Japan and South Africa have also been recently invaded by Carcinus, although genetic analyses indicate that these may include some hybrids among two species: C. maenas and C. aestuarii. The possible mechanisms (or vectors) responsible for these green crab invasions include dry ballast, ballast water, transfer with aquaculture species or release of teaching material.
Green crabs are known to be voracious predators, preferring bivalves and other infaunal organisms, but are also known to prey on other species of crabs. Carcinus maenas inhabit a wide variety of habitats and environmental conditions, and appear to be responsible for broadscale changes in invertebrate communities, including commercially important species. In addition, green crabs may have a myriad of effects in vertebrate and invertebrate populations. Our research focuses on the direct and indirect effects of green crabs on invaded ecosystems.
Research Components:
Abundance/ Distribution Patterns: We conduct extensive trapping and dive surveys to determine abundance and distribution of green crabs and native crabs, as well as to measure their population characteristics (density, size structure, etc). Using mark-recapture methods, we also estimate population size, dispersal rates, and individual growth rates. We conduct additional surveys of infaunal, bivalve, and gastropod communities to characterize temporal/spatial patterns of native invertebrate and vertebrate abundance, testing for correlation with green crab population characteristics.
Environmental Limits: Lab experiments have been conducted at SERC for the last few years to determine the temperature and salinity limits of the zooeal, megalopal and juvenile stages of Carcinus. Using standard rearing methods, crab larvae have been raised at temperatures ranging from 5 to 30ºC at salinities of 20 or 30ppt. We hope to gather a better understanding of the abiotic limits of this crab and to be able to better predict its expansion and invasion patterns.
Effects on Invertebrate Populations: Short-term field experiments are used to test for significant direct and indirect interactions between green crabs and native species. Lab experiments are also used to measure prey preferences, feeding rates, functional responses, and other behavioral attributes.
Study Sites:
Selected Publications:
Hines, AT, Ruiz, GM, Hitchcock, NG, and C DeRivera. 2004. Projecting Range Expansion of Invasive European Green Crabs (Carcinus maenas) to Alaska : Temperature and Salinity Tolerance of Larvae. Final Report to Prince William Sound Regional Citizens' Advisory Council.
Edited: Thresher, RE. 1997. Proceedings of the First International Workshop on the Demography, Impacts, and Management of Introduced Populations of the European Green Crab, Carcinus maenas. CSIRO Marine Laboratories, Hobart, Tasmania. CSIRO-CRIMP.
Geller, JB, Walton W, Grosholz ED, and Ruiz GM. 1997. Cryptic invasions of the crab Carcinus detected by molecular phylogeography. Molecular Ecology, 901-906.
Grosholz, ED and Ruiz GM. 1996. Predicting the impact of introduced species: lessons from the multiple invasions of the European green crab. Biological Conservation, 78: 59-66.
Grosholz, ED and Ruiz GM. 1995. Spread and potential impact of the recently introduced European green crab, Carcinus maenas, in central California. Marine Biology, 122: 239-247.
Other Green Crab Websites:
|
