Volumen 45 - Número 1: 255-265 | 2010
Article

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Morphological and growth alterations on early development stages of Iridaea cordata (Rhodophyta) under different intensities of UVB radiation

Nelso P. Navarro^1,2*, Mauricio Palacios¹, Andrés Mansilla^1,3 and Jocelyn Jofre¹

¹Departamento de Ciencias y Recursos Naturales, Facultad de Ciencias, Universidad de Magallanes, Casilla 113-D, Punta Arenas, Chile

²Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, Rua do Matão 277, CEP 05508-090, Cidade Universitária, Butantã, São Paulo, Brasil

³Instituto de Ecología y Biodiversidad, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago, Chile

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This study describes the effects of different intensities of UVB radiation on growth and morphology of early development stages of Iridaea cordata in germlings, young gametophytes originated in the laboratory and young fronds collected in the Magellan Strait, Chile. The experiments were carried out during four weeks in controlled conditions of temperature and photoperiod and the results were compared with a control treatment (without UVB). All UVB irradiation treatments caused bleaching and decrease in growth rates of germlings. Additionally, initial upright fronds were not observed in any of the UVB treatments, where as those cultivated in UVB absence developed erect ones in the second week of culture. The young gametophytes exhibited morphological alteration (small number and size of basal ramifications, curling of tips, bleaching and necrosis) and decrease in growth when exposed to UVB radiation. Young fronds collected from the field showed mainly morphological alterations (curling of frond). Morphological alterations in young gametophytes and young fronds of I. cordata could be interpreted as a defense against UVB by reducing the area exposed to radiation. However, high level of UVB radiation can produce irreparable damage, such as necrosis, observed in young gametophytes originated in the laboratory. Finally, the UVB effects on early developmental stages of I. cordata depend on the UVB irradiance and time of exposition.

Key words: Algae, growth, germlings, Magellan Strait, morphology

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