European green crab,Carcinus maenas

European Green Crab ( Carcinus maenas) 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 it 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, 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.

European 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. They 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.

• Effects on Shorebird Populations: Regular surveys are conducted to test for the indirect effects of green crabs, through food-based competition, on wintering shorebirds.

• Eradication of Invasive Species: An eradication effort is underway to remove European Green Crabs from Seadrift Lagoon, an artificial lagoon adjacent to Bolinas Lagoon California. This is a community effort involving volunteers from the local area.  
   

Selected Publications:

de Rivera CE, Steves BP, Fofonoff PW, Hines AH, Ruiz GM (2011) Potential for high latitude marine invasions along western North America. Diversity and Distributions 17: 1198-1209

de Rivera CE, ED Grosholz , GM Ruiz. 2011. Multiple and long term impacts of an introduced marine predator. Marine Ecology Progress Series. 429:145-155.

de Rivera CE, GM Ruiz, NG Hitchcock, SA Teck, B Steves, AH Hines. 2007. Larval development rate predicts range expansion of an introduced crab. Marine Biology 150:1275-1288.

de Rivera CE, GM Ruiz, AH Hines, P Jivoff. 2005. Biotic resistance to invasion: native predator limits abundance and distribution of an introduced crab. Ecology 86:3364-3376

Hines, AT, GM Ruiz, HG Hitchcock, and CE de Rivera. 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, W Walton, ED Grosholz, and GM Ruiz. 1997. Cryptic invasions of the crab Carcinus detected by molecular phylogeography. Molecular Ecology, 901-906.

Grosholz, ED and GM Ruiz. 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 GM Ruiz. 1995. Spread and potential impact of the recently introduced European green crab, Carcinus maenas, in central California. Marine Biology, 122: 239-247.