Doses of darkness control latitudinal differences in breeding date in the barnacle Semibalanus balanoides

• Main Authors: J. Davenport, M. S. Berggren, T. Brattegard, N. Brattenborg, M. Burrows, S. Jenkins, D. McGrath, R. MacNamara, J.-A. Sneli, G. Walker, S. Wilson
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2005
• Subjects: Arctic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.174.4034; http://www.sos.bangor.ac.uk/%7Eoss406/Davenport%20et%20al%202005.pdf

This paper reports the first study of breeding in the boreo-arctic barnacle Semibalanus balanoides in which latitudinal variation in timing of egg mass hardening has been examined simultaneously over the geographical scale involved, thereby excluding temporal confounding of the data. The timing of autumn egg mass hardening on the middle shore was established in 2002 and 2003 at ten stations ranging latitudinally from Trondheim (63824 0 N) to Plymouth (50818 0 N). To assess variation at local scale (510 km), breeding was studied on three shores at each of two Irish locations (Cork and Galway). At Oban (Scotland) and Cork, the effect of shore height on timing of breeding was investigated. A strong influence of latitude and day length on timing of breeding was found in both 2002 and 2003. In both years, barnacles bred much earlier (when day length was longer) at high rather than low latitudes. No significant effect of environmental temperature or insolation on timing of breeding was detected. Shores no more than 10 km apart showed minimal difference in middle shore breeding date (54 days). However, upper shore barnacles bred significantly