Dulse Palmaria mollis as a settlement substrate and food for the red abalone Haliotis rufescens

Abstract

Dulse ( Palmaria mollis) was used as a settlement substrate and as a food for different stages of the life-cycle of the red abalone ( Haliotis rufescens). Dulse was found to be superior to kelp ( Nereocystis luetkeana) in conditioning broodstock, resulting in eggs of higher dry weight, lipid and protein content. Improved egg quality resulted in higher hatching and metamorphosis success of larvae. Dulse was comparable to diatom coatings as a substrate for settlement and growth of post-larvae, although direct utilization of dulse as a food source was only evident in abalone >3 mm in shell length. Juvenile abalone 3 to 6.5 mm in shell length grew faster on dulse than on diatom coatings. Abalone 10 mm in shell length grew well when fed on dulse over a 12-month period, with monthly shell growth rates varying from 1.3 mm in January (seawater temperature 8.7°C) to 3.8 mm in July (seawater temperature 14°C). Use of dulse throughout the abalone's life cycle should simplify the production process and reduce costs.