R. Scrosati, Mechanisms of recolonization of the clonal intertidal alga Mazzaella cornucopiae (Rhodophyta, Gigartinaceae) after disturbances, CAN J BOTAN, 76(10), 1998, pp. 1717-1724
Citations number
44
Categorie Soggetti
Plant Sciences
Journal title
CANADIAN JOURNAL OF BOTANY-REVUE CANADIENNE DE BOTANIQUE
The recolonization of the clonal intertidal alga Mazzaella cornucopiae (Pos
tels et Ruprecht) Hommersand is considered here, as part of a larger projec
t on its population ecology. Recolonization in Barkley Sound, Pacific Canad
a, started a few months after completely clearing experimental 100-cm(2) qu
adrats in late spring and occurred both by vegetative growth of perennating
holdfasts bordering disturbed quadrats and by recruitment from spores. In
terms of percent cover, both mechanisms contributed similarly to recoloniza
tion during the first 2 years, although vegetative recolonization was highl
y variable among quadrats. Great spatial variability prevented the detectio
n of a temporal pattern for recruit density on statistical grounds. However
, cohort demography showed some degree of seasonality. Turnover rates of re
cruits were high; they lived 2.6 months on average. Recruitment was highest
between fall or winter and midspring (as might be expected, given that rep
roductive structures appeared in fall and winter) and null in the first two
summer seasons. The highest mortality was recorded in summer, when desicca
tion and irradiance are highest on an annual basis. Frond density was very
variable on a spatial scale and did not follow a clear temporal pattern. Th
e average number of fronds per recruit apparently increased between winter
and summer, paralleling frond dynamics in mature stands. By monitoring reco
lonization in quadrats of the same size cleared previously by other researc
hers, the time of full recovery of M. cornucapiae was estimated to be 2.7-3
.5 years.