The edible brown seaweed Alaria esculenta (Phaeophyceae, Laminariales): hybridization, growth and genetic comparisons of six Irish populations

Alaria esculenta populations from six different geographical locations on t he Irish coast were examined for hybridization abilities, growth rates and genetic make-up with a view towards identifying a fast-growing strain suita ble for aquaculture. Hybridization experiments under laboratory conditions with the three most geographically dispersed populations showed that all cr oss combinations were interfertile, although differences were found in surv ival, and in blade and hapteron morphology. A comparison of relative growth rates showed significant differences amongst the self-crosses and hybrids. The data of the hybridization experiments and growth rates under laborator y conditions show that the best population for the purpose of seaweed aquac ulture are the Slea Head and Corbet Head self-crosses and their hybrids. Ge netic fingerprinting of the internal transcribed spacer of the ribosomal DN A of five A. esculenta isolates from geographically separated populations i n Ireland revealed no restriction length polymorphisms between the tested i solates and show that the A. esculenta populations around the Irish coast a re clearly genetically homogenous in respect of the DNA region examined. Th e genetic analysis, interfertility of the populations, morphology and growt h rates are discussed with a view to potential cultivation.