This thesis assessed the ability to control metamorphosis in the commercially important king scallop, Pecten maximus and blue mussel, Mytilus edulis
using chemical inducers. It also investigated the influence of environmental
factors on attachment and dispersal of their motile post-larvae. The aim
was to increase our understanding of bivalve biology and behaviour, and provide useful tools for aquaculture.
The influence of potassium chloride (KCl), ammonium chloride (NH4Cl), acetylcholine chloride, γ-aminobutyric acid (GABA), L-3,4-dihydroxyphenylalanine (L-DOPA) and epinephrine was assessed on larval P. maximus metamorphosis and mortality over a range of concentrations. 20mM KCl and 10-6M L- DOPA induced development 208% and 128% higher,
respectively, than untreated controls after 7 days. The KCl treatment was toxic, reducing survival by 33%, whilst the L-DOPA treatment
significantly increased survival by 49%.
The influence of L-DOPA, epinephrine, KCl and NH4Cl over a range of concentrations and exposure periods was assessed on M. edulis larval metamorphosis, mortality and growth. No chemical provided a lasting improvement in metamorphosis compared to a control. KCl induced a slight improvement in growth at concentrations of 1.3x10-3M and 1.3x10-2M
after exposure for 24 and 48 hours, without compromising survival.
A series of experiments assessed the impact of substrate, attachment period, food availability, water agitation, seed densityand pedal activity on attachment and retention of M. edulis seed. Substrate type and length of attachment period affected attachment. Feeding seed increased detachment, although
water agitation increased retention. Detachment and dispersal was proportional to seed density, and dependent upon substrate type, with loss higher from glass than from wool materials. Seed crawling activity could also be used as a predictive test of future seed mortality.
The impact of substrate type, substrate pre-conditioning, length of
attachment period, feeding ration, agitation and illumination were assessed
on the attachment of juvenile P. maximus scallops. Substrate type, pre-
conditioning and feeding ration was also assessed on juvenile detachment
over increasing water velocities. Recommendable parameters for maximising attachment and retention in water velocities up to 12.6±0.2cm second-1
include utilising a slate substrate, pre-conditioned for 1 week, feeding a diet of at least 0.025g microalgae.g-1 juveniles.week-1, and allowing to attach for at
least 24 hours