RAPID GROWTH OF CLONES OF THE RED ALGA CHONDRUS-CRISPUS - APPLICATIONS IN ASSAYS OF TOXIC-SUBSTANCES AND IN PHYSIOLOGICAL-STUDIES

Growth rates of excised apical segments from three Chondrus crispus St ackhouse clones were rapid, reproducible and easily measured using sim ple equipment. Clonal segments exhibited a high degree of phenotypic s tability, with coefficients of variation in growth rates being typical ly less than 5%. Sensitivity of the assay was demonstrated using 24-h pulses of the toxicants Cu2+ (10 to 150 ppb) and the molluscicide Bayl uscide (100 to 500 ppb). As a further demonstration of applicability o f this assay system, growth rates were measured over two consecutive 2 4-h photoperiods using a normally pigmented red gametophytic clone and a green colored mutant derived from it. Growth rates were highest in the first hours of the light phase for both clones, with growth of the green mutant being consistently inferior to that of the normally pigm ented one. Significant changes were measured with intervals as short a s 4 h using only five apical segments for each treatment. The C. crisp us assay described is sensitive, relatively rapid, and statistically r obust when applied to toxicant testing in seawater and to physiologica l studies.