Epiphytism in a subtidal natural bed of Gracilaria gracilis of southwestern Atlantic coast (Chubut, Argentina)

MARTÍN LUCAS; BORASO ALICIA; MIRAVALLES ALICIA,; RODRIGUEZ CECILIA; LEONARDI, PATRICIA

JOURNAL OF APPLIED PHYCOLOGY

SPRINGER

Año: 2013 vol. 25 p. 1319 - 1329

0921-8971

The diversity of epiphytes, their temporal abundance variation and the anatomical structure of host-epiphyte interfaces were studied in the agarophyte Gracilaria gracilis from a natural bed in Bahía Bustamante, Chubut province, Argentina. Twenty-nine algal species were recorded as epiphytes during two years of monthly sampling (March 2006 - February 2008). Total epiphyte density ranged between 0.037 ind.cm-2 (November 2006) and 39.37 ind.cm-2 (April 2007), with higher density values throughout the second sampling year. Ceramiales species were the most abundant epiphytes. Ceramium rubrum?s density ranged from 0.09 ind.cm-2 (52% of the total amount) in September 2006 to 17.4 ind.cm-2 (44.18% of the total amount) in April 2007. Epiphyte infection was more dependant on spore recruitment and sporeling development, especially on thalli derived from fragmentation, than on seasonal environmental variations. The different infections were analyzed taking into account the epiphytic attachment strength and invasiveness, and the degree of damage inflicted on the host. Calothrix confervicola was one of the most abundant species. This epiphyte, weakly attached to the host surface, generated nil host-tissue damage. In contrast, Ceramium rubrum, Polysiphonia abscissa and other Ceramiales were the species that caused more damage to the host because their rhizoids penetrated the cortical portion, sometimes reaching the medullary tissue. Some generalizations and characterizations of the different epiphyte groups in relation to their consequences to Gracilaria spp. are presented.