European Green Crab, Carcinus maenas
Green Crab Larval Development Research
Catherine De Rivera, Natasha Gray Hitchcock, Sarah Teck, Brian Steves, Tuck Hines, and Greg Ruiz
For the last several years, we have been conducting lab experiments to better understand the conditions under which Carcinus larvae are able to survive. By examining the limits of their tolerance at each larval stage, we hope to discover where they can invade and survive. In order to predict what areas may be susceptible to future Carcinus invasions, we need to answer the following questions:
What are the temperature and salinity tolerances at each stage of larval development?
How do temperature and salinity affect the duration of larval development?
Do temperature and salinity tolerances differ between the native population in Europe, the invasive Eastern and Western US populations?
Green crabs live in embayments and on rocky shores in the intertidal zone in salinities ranging from about 10 to 33 ppt. Breeding has been successful in water as fresh as 13ppt. Green crabs are generally found in areas with average temperatures between 22ºC and -1ºC, with a maximum for adult crab survival at about 35ºC when acclimated to 22ºC. Temperatures below 7ºC inhibit adult feeding and below 10ºC inhibit growth. Die offs occur in sever winters, but there is at least a partial migration offshore to areas of warmer and/or saltier water.
Green crab eggs hatch into free swimming zoea which feed on phytoplankton and small zooplankton. They molt two times as zoea and on the third molt, they become megalops. Once at the megalop stage, they settle out of the water column to search for a suitable area where they then molt to a juvenile crab. The juvenile crabs molt many times, growing larger as they do so. Crab larvae are much more sensitive to environmental conditions than are adults. Salinity needed for larval development is thought to be 20ppt and greater. Most experiments have reared larvae above 10ºC (zoea do not develop at 6ºC, zoea).
To look at the west coast population, we collected ovigerous female crabs from the intertidal in Bodega Bay, California and transported them to SERC. Upon hatching, zoea were placed in various salinity and temperature conditions for rearing. Temperatures ranged from 5ºC to 30ºC at 2.5ºC increments. Larvae were monitored daily and molt stage recorded until mortality or development to the juvenile crab stage.
Our results confirm previous data that larvae below 10ºC do not develop beyond zoea I. Larvae in a salinity of 20ppt, at any temperature, also do not develop. Larvae reared above 22.5ºC developed quickly to subsequent molt stages but died before molting to megalopae. There was also a strong negative correlation between temperature and development time.
These data were published in 2004 and 2007
deRivera CE, NG Hitchcock, SJ Teck, BP Steves, AH Hines and GM Ruiz. 2007. Larval development rate predicts range expansion of an introduced crab. Marine Biology doi: 10.1007/s00227-006-0451-9
Hines, AT, GM Ruiz, NG Hitchcock, and CE, 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.
© copyright 2004