Effects of surface orientation and slurry coating on settlement of Sydney rock, Saccostrea commercialis, oysters on PVC slats in a hatchery

Hatchery reared pediveliger larvae of Sydney rock (Saccostrea commercialis) oysters settled within 10-litre aquaria, on PVC slats and on PVC slats coated with a lime and cement slurry. Settlement on horizontally positioned slats (76.6% of larvae settled; 23.8 spat/cm 2 ), was significantly (P < 0-001) higher than on vertically positioned PVC slats (0-71% of larvae settled; 0-2 spat/cm 2 ). Larval settlement was significantly lower (P < 0.01) on horizontally positioned slats coated with a cement slurry (60.2% of larvae settled; 18.7 spat/cm 2 ). Significantly higher (P < 0.01) settlement was recorded from the under surface of horizontally positioned slats and slurry-coated slats (46.2 and 35.0 spat/cm 2 , respectively) than from their upper surfaces (1.2 and 2.4 spat/cm 2 , respectively). However for vertically positioned slats, settlement was similar (P > 0.05) for the convex and concave surfaces (0.3 and 0.2 spat/cm 2 , respectively). These results indicate that PVC slats and slurry-coated PVC slats positioned horizontally are suitable for settlement of Sydney rock oyster larvae in a hatchery and may be suitable for remote setting. © 1996 Elsever Science B.V.