Journal of the Marine Biological Association of the United Kingdom

Research Article

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

J.  Davenport a1c1, M.S.  Berggren a2, T.  Brattegard a3, N.  Brattenborg a3, M.  Burrows a4, S.  Jenkins a5, D.  McGrath a6, R.  MacNamara a1, J.-A.  Sneli a7, G.  Walker a8 and S.  Wilson a5
a1 Department of Zoology, Ecology and Plant Science and Environmental Research Institute, University College Cork, Lee Maltings, Prospect Row, Cork, Ireland
a2 Kristineberg Marine Research Station, SE-450 34 Fiskebäckskil, Sweden
a3 Department of Biology, University of Bergen, PO Box 7800, NO-5020 Bergen, Norway and The School Centre for Science Education, University of Bergen, Allégaten 41, N-5007 Bergen, Norway
a4 Scottish Association for Marine Science, Dunstaffnage Marine Laboratory, Oban, Argyll, PA37 1QA, Scotland, UK
a5 Marine Biological Association of the United Kingdom, Citadel Hill, Plymouth, PL1 2PB, UK
a6 Life Sciences Department, Galway-Mayo Institute of Technology, Dublin Road, Galway, Ireland
a7 Institute of Biology/Trondhjem Biological Station, Norwegian University of Science and Technology, N-7451, Trondheim, Norway
a8 School of Ocean Sciences, University of Wales Bangor, Menai Bridge, Anglesey, LL59 5AB, UK

Article author query
davenport j   [PubMed][Google Scholar] 
berggren ms   [PubMed][Google Scholar] 
brattegard t   [PubMed][Google Scholar] 
brattenborg n   [PubMed][Google Scholar] 
burrows m   [PubMed][Google Scholar] 
jenkins s   [PubMed][Google Scholar] 
mcgrath d   [PubMed][Google Scholar] 
macnamara r   [PubMed][Google Scholar] 
sneli ja   [PubMed][Google Scholar] 
walker g   [PubMed][Google Scholar] 
wilson s   [PubMed][Google Scholar] 


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 (63°24′N) to Plymouth (50°18′N). To assess variation at local scale (<10 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 (<4 days). However, upper shore barnacles bred significantly earlier (by 7–13 days) than middle shore animals. The data indicate that breeding is controlled by period of daily darkness, with high shore animals encountering longer effective ‘nights’ because of the opercular closure response to emersion (which will reduce light penetration to tissues). Predictions concerning the effects of global changes in climate and cloud cover on breeding and population distribution are made. It is suggested that increased cloud cover in the northern hemisphere is likely to induce earlier breeding, and possibly shift the present southern limit of Semibalanus southwards.

(Received June 23 2004)
(Accepted November 24 2004)

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