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Title: The population dynamics of Halecium petrosum and Halecium pusillum (Hydrozoa, Cnidaria), epiphytes of Halimeda tuna in the nortwestern Mediterranean
Author: Coma Bau, Rafel
Llobet i Nadal, Immaculada
Zabala i Limousin, Mikel
Gili, Josep Maria, 1953-
Hughes, R.G.
Keywords: Invertebrats marins
Mediterrània, Mar
Marine invertebrates
Mediterranean Sea
Issue Date: 1992
Publisher: Consejo Superior de Investigaciones Científicas (CSIC)
Abstract: Halecium petrosum and Halecium pusillum on the alga Halimeda tuna from Tossa de Mar, northeastern Spain, were studied. Asexual reproduction of H. petrosum, by stolonisation, occurred throughout the year except for July and August. Asexual reproduction of H. pusillum, by planktonic propagules, occurred throughout the year. Sexual reproduction was limited to the autumn in H. petrosum and spring in H. pusillum. The growth rates of colonies of both species were rapid but declined with increased size. Mean colony size over two consecutive two week periods increased approximately five-fold and three-fold for H. petrosum, and six-fold and four-fold for H. pusillum. Mortality was estimated to be high for both species, especially in summer. The maximum life span of colonies (ramets) of both species was estimated to be only eight weeks. Consequently most colonies do not reproduce sexually. The absence of reproduction of H. petrosum in summer, when the turnover of algal thalli was greatest, probably contributed to the summer decline in its abundance. In both species the genet (clone) survives for unknown, possibly very long, periods by asexual reproduction which facilites colonisation of other substrata.
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It is part of: Scientia Marina, 1992, vol. 56, num. 2-3, p. 161-169
ISSN: 0214-8358
Appears in Collections:Articles publicats en revistes (Biologia Evolutiva, Ecologia i Ciències Ambientals)

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