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THE ECOLOGY OF CHONDRUS CRISPUS AT PLYMOUTH, MASSACHUSETTS. II. FIELD STUDIES
Author(s) -
Prince Jeffrey S.,
Kingsbury John M.
Publication year - 1973
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1973.tb05997.x
Subject(s) - biology , spore , epiphyte , propagule , frond , population , botany , reproduction , germination , population density , ecology , horticulture , demography , sociology
Growth and reproduction were examined periodically through a full year at four stations located in a dense population of Chondrus . Growth rates of germlings and of mature plants reach a maximum in late summer and a minimum in winter, paralleling temperature. At the time of maximum growth, nitrate is at its lowest seasonal concentration. Ammonia, however, is available and apparently utilized. Fronds are smaller but more numerous at −3 m MLW than at −6 m MLW and deeper and regrow from holdfasts with twice the original density after removal. Large fronds are torn off by storms at lesser depths. The average weight and density varies with season and possibly with depth. Chondrus at Plymouth is similar to populations investigated elsewhere in average density of plants per unit area, but the average weight per unit area was approximately twice that reported for other populations. Presence or absence of sori gives a false picture of reproductive periodicity because at some seasons most sori are empty or contain non‐viable spores. Carposporic reproduction reached a sharp maximum in October. Tetrasporic reproduction did likewise, with an additional lesser peak in May. At the time of greatest reproductive intensity, approximately half of all mature plants were shedding spores. Spores settle, germinate, and produce germlings successfully on initially sterile surfaces; no prior macroscopic or microscopic successional events are required. Seasonal composition of associated flora and epiphytes of Chondrus are discussed.