Settlement pattern and survival of a shell-infesting sabellid polychaete, <i>Terebrasabella heterouncinata</i>, on South African abalone, <i>Haliotis midae</i>, fed two diets

Abstract

This study tested whether abalone diet influences larval settlement success of the shell-dwelling sabellid polychaete Terebrasabella heterouncinata and their survival over the first 96h after settlement on host abalone. Shell area preferences of the sabellid were also investigated. Abalone diet (fresh kelp, Ecklonia maxima or Abfeed™) did not affect sabellid settlement success (F_1,30 = 1.05; p <= 0.31). There were significant differences in settlement between shell regions, with the highest number of sabellids settling near the respiratory pores (F_2,30 = 61.0; p < 0.001). Percentage occupation rate of tubes 96h after settlement did not differ between dietary treatments. There were no significant interactions between diet and shell region for sabellid settlement (F_2,30 = 0.77, p = 0.69) and tube formation (F_2,30 = 1.02, p = 0.67) or for the percentage occupation rate of the tubes (F_9,180 = 0.11, p = 0.73). Thus, infestation intensity in relation to shell region can be estimated independent of abalone diet. For treatment purposes, total settlement after 36 days of exposure can be used to identify the shell areas on which most sabellids will be found.

Keywords: abalone shell region, aquaculture, infestation intensity, shellfish diseases

African Journal of Aquatic Science 2007, 32(3): 275–279