Consistent spatial patterns of arrival of larvae of the honeycomb barnacleChamaesipho tasmanica Foster and Anderson in New South Wales

The small honeycomb barnacle Chamaesipho tasmanica occurs in patches at hig h levels on exposed rocky shores, but often carpets the substratum at mid-s hore levels of sheltered shores in south-eastern Australia. Studies of larv al supply from 1990 to 1993 and concurrent monitoring of settlement from 19 91 to 1993 revealed that larval arrival and settlement were typified by tri ckles of larvae from late July to December (although some were observed in January and February). Major pulses of arriving cyprids were also recorded once or twice each year. While local patterns of water-flow had no impact o n numbers of larvae arriving, major peaks of larval arrival were always ass ociated with strong southerly winds during new and full moons. There was a consistent spatial pattern of larval supply; more larvae were always caught in one area low on the shore. Numbers of larvae caught were, however, very sporadic within a given year and very variable from one year to the next. While the different numbers of cyprids in different places cannot be explai ned by cyprids arriving first on lower parts of the shore, longer periods o f submersion nor aggregations of larvae in the plankton, recurrent patterns of arrival of larvae suggest that local site-specific characteristics have an influence on the demography of populations of this species. Variations in numbers of larvae arriving were responsible for the variations in distri butions of juveniles on the substratum. Crown copyright (C) 2000 Published by Elsevier Science B.V. All rights reserved.