ABSTRACT: Field observations using settlement panels, which werecarried out in Port Daniel Bay, Baie des Chaleurs, Québec, Canada, in 1992, showed recruitment by the hydroid Tubularia larynx to be unevenly distributed with depth. Multiple regression on residuals indicated that 2 physical factors, water temperature and light intensity, out of 5 tested explained 45% of the observed variance in the recruitment of T. larynx on the panels. In laboratory experiments, warm temperatures increased settlement significantly. Contrary to field results, light intensity did not seem to influence the settlement of T. larynx in the laboratory. The influence of small scale (T.larynx. The influence of extracts and metabolites of conspecific adults on larval settlement was also tested in the laboratory and field. Adult extracts had some influence on settlementin some laboratory trials, but not in others. In general, T. larynx settled more abundantly on surfaces treated with high concentrations of extract solutions than on other surfaces. As was the case for substratum heterogeneity, there was no influence of adult extracts detected in the field. In contrast, adult metabolitesshowed little influence on settlement under laboratory conditions and no influence on recruitment in field experiments.

KEY WORDS: Hydroid · Tubularia larynx · Settlement · Recruitment · Physical factors · Biochemical factors

Published in MEPS Vol. 140 (1996) on September 12
ISSN: 0171-8630. Copyright © Inter-Research, Oldendorf/Luhe, 1996