Effects of delaying settlement on the life expectancy of the bryozoan Bugula flabellata (Bryozoa: Gymnolaemata) Efectos del retardo del asentamiento en las expectativas de vida del briozoo Bugula flabellata (Bryozoa: Gymnolaemata)

Abstract

In the presence of a suitable substratum the lecithotrophic larvae of the bryozoan Bugula flabellata preferentially settle within the first six hours after hatching, whereas a marginal percentage of them (≈ 1 %) delay settlement between 6 and 24 h after larval release. In the present study we report that larvae of B. flabellata forced, by mechanical water shaking, to delay their settlement from 6 to 57 h, significantly reduced their fitness. Bugula flabellata larvae keep their capacity to settle in a level near to 95 % during the first 24 h after release. Hereafter only 30 % of the larvae forced to delay settlement for 24 to 48 h was able to settle. Furthermore, larval metamorphosis quickly decreased from an initial ≈ 100 % value to less than 50 % after 6 h of a forced delayed settlement. Colonies generated by larvae forced to delay settlement for 48-54 h generated colonies that after 21 days of growth had in average a smaller number of zooids than colonies generated by larvae forced t