R. Scrosati, Regeneration and reproduction of Mazzaella cornucopiae (Rhodophyta, Gigartinaceae) after frond harvesting, J APPL PHYC, 10(6), 1998, pp. 531-537
The effects that different intensities of frond harvesting have on frond re
generation and subsequent production of reproductive structures were invest
igated for the red intertidal alga Mazzaella comucopiae (Postels & Ruprecht
) Hommersand from British Columbia, Canada. Harvesting was done by pruning
fronds in the late spring (when stand biomass is highest) of 1993 at two in
tensities: total and partial collection of fronds, in this second case leav
ing all frond biomass less than 1 cm high in place. Holdfasts were not dama
ged. Total percent cover of thalli, frond density, mean frond length, and s
tand biomass for these experimental quadrats were statistically similar to
values for control quadrats in the spring of 1994. These results suggest th
at one total harvest of fronds per year, done in late spring without damagi
ng holdfasts, may give the highest sustainable yield of biomass. The effect
s of harvesting intensity on reproduction were variable and difficult to ex
plain. Neither the appearance nor the abundance of cystocarpic fronds were
affected by frond pruning, compared with control areas, but pruning did aff
ect the appearance and the abundance of tetrasporic fronds. Partial pruning
resulted in a longer presence of tetrasporic fronds, whereas total pruning
was associated with their complete absence. Results are compared with thos
e for the few other species of the Gigartinaceae for which experimental har
vesting has been done.