Reproductive Capacity of Dragraked and Non-Dragraked Irish Moss (Chondrus crispus Stackhouse) Beds in the Southern Gulf of St. Lawrence

Abstract

A non-dragraked bed of Chondrus crispus Stackhouse (Rustico) showed a greater year-round carposporangial reproductive capacity than a dragraked bed (Miminegash). The former had a lower frond density but larger fronds which were the major sources of reproduction. Although carposporangial sori had a greater area and were more frequently full in Miminegash, reproductive capacity was higher in Rustico due to higher sorus densities per frond and sample unit. All the studied parameters did not show significant (P = 0.05) differences between the study sites for tetrasporophytes, resulting in similar overall tetrasporangial reproductive capacities. Reproductive capacity peaked in Miminegash prior to the harvesting season. Class 4 and 5 fronds (largest fronds) have the greatest reproductive capacity. To protect this source of spores and thus improve bed reproductive potential, a 1-mo delay in the present season opening date is suggested. The much higher tetrasporophyte reproductive capacity over that of carposporophytes is at least a partial explanation for the greater gametophytic abundance in some populations.