CERAMIALEAN EPIPHYTISM IN AN INTERTIDAL GRACILARIA-CHILENSIS (RHODOPHYTA) BED IN SOUTHERN CHILE

The cultivation of the agarophytic red alga Gracilaria has become an a ctivity of major importance in several parts of the world. However, Gr acilaria cultivation in Chile still faces problems such as epiphytism. We report ceramialean epiphytism abundance, recruitment patterns and the microscopic stages fixed on the Gracilaria thalli in an intertidal bed (Metri bay) of southern Chile. Using a factorial field experiment , we analyze the effect of intertidal elevation and the use of epiphyt e free inoculum on the abundance of ceramialean epiphytic algae. This evidence is used to provide management and control recommendations for ceramialean epiphytes. The results show a summer recruitment and incr ease in abundance of ceramialean epiphytes. A seasonal and spatial pat tern of abundance of microscopic stages of this epiphytic algae was al so found, showing a significant increase from the apical (new tissues) to the central parts of the thalli (older tissues). Apical tissues ar e free of epiphytic propagules. The epiphyte-free tissue zone decrease s significantly from winter to summer. Also, a significantly higher de nsity of microscopic stages of ceramialean epiphytes was found on the thalli collected in the farming area during the summer at low tidal le vels. The experimental results indicated that the abundance of epiphyt es was greater at the lower tidal levels than at the higher distributi on limits of Gracilaria and it was not possible to control epiphytism by manual cleaning.