RBMO 47(1): 109-119 | 2012
Article

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Blades and papillae as likely dispersing propagules in Chilean populations of Mastocarpus sp. (Rhodophyta, Gigartinales)

Mauricio H. Oróstica^1,2, Ricardo D. Otaíza^3* & Paula E. Neill³

¹Centro Regional de Investigación y Desarrollo Sustentable de Atacama (CRIDESAT) CONICYT-REGIONAL R06I1003, Avda. Copayapu 485, Copiapó, Chile
²Programa de Magíster Ciencias del Mar, Facultad de Ciencias del Mar, Universidad Católica del Norte, Avda. Larrondo 1281, Coquimbo, Chile
³Departamento de Ecología, Facultad de Ciencias, Universidad Católica de la Santísima Concepción, Concepción, Chile

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Mastocarpus sp. is a red macroalga native to the Pacific coast of North America, and present around Concepción, Chile (ca., 37°S), where it has been suggested as a non-indigenous species. Its establishment and expansion could be favored if blades and papillae function as propagules. The characteristics of the detachment of these two structures support this interpretation. Blades of Mastocarpus sp. become detached from rocks more readily than other common, bladed red seaweeds. In turn, a monthly estimate of up to 14.9% of papillae carrying mature cystocarps easily broke off from blades when experimentally subjected to turbulence in the laboratory. Additionally, blades and papillae are commonly found drifting, and release normally pigmented spores. The distribution of papillae along the blades, considering their maturity, suggests a predictable detachment pattern. New papillae were more abundant on distal segments, old papillae on middle segments, and scars of shed papillae on basal segments, suggesting that shed papillae carried mature cystocarps. We conclude that blades and papillae have attachment points that become relatively weaker as they grow and mature, facilitating their detachment. This does not represent abscission of empty or senescent structures because carposporophytes growing inside these structures still carry spores that can be released. Thus, blades and papillae may be important in facilitating the establishment of new individuals at distances and places different from what is achieved by spores and, hence, could be considered as alternative dispersing entities. As such, they could affect the population dynamics and range expansion of Mastocarpus sp. in Chile.

Key words: Detachment, dislodgment, dispersal strategy, drifting fragments, non-indigenous species, Phyllophoraceae

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