Epi-endophytism in Undaria pinnatifida from Argentina.

GAUNA, M. C.; PARODI, E. R.; CACERES, E. J.

Kobe, Japon

Simposio; XIX International Seaweed Symposium; 2007

JSA, JSP y JMSB

Undaria pinnatifida (Harvey) Suringar is an edible brown kelp cultured off the coasts of Korea, China and Japan. While its proliferation is encouraged and indeed nurtured in several places, in other is seen as a terrible nuisance species, a threat to the health and therefore the focus of containment and eradication efforts. U. pinnatifida is widely distributed in Europe, Asia, Mexico, Australia and New Zealand. In December 1992, was detected for the first time in Argentina, in Puerto Madryn. Since then, ecological and morphological studies have been done, but the present is the first study on epi-endophytic algae on thalli from Argentinian coasts. Collections of Laminariocolax aecidioides growing in sporophytes of U. pinnatifida were made during June and December 2004. They were observed as dark zones formed by confluent points, 1-2 mm in diameter that covered U. pinnatifida fronds partially. In nature, L. aecidioides presented filamentous vegetative thalli, uniseriate and branched. L. aecidioides is described from laboratory cultures. Small fragments of the cortical layer of U. pinnatifida were excised and cultures in PES medium. Cultures were maintained at 21 1ºC, with an illumination regime of 12:12 h LD and a photon flux density of 15umol m-2s-1. Isolates developed into filamentous-branched microcopic thalli. They were sporophytes that reproduced by both unispores and plurispores fron unilocular and plurilocular sporangia. L. aecidioides presented a cycle life constituted by two microscopic generations and isogamy. The sporophytic diploid phase presented 16 chromosomic and the gametophytic haploid phase 8 chromosomic.