Intimate Associations Between Epiphytes, Endophytes, and Parasites of Seaweeds

A comprehensive study of Antarctic algal symbioses: minimal impacts of endophyte presence in most species of macroalgal hosts

“…The relationships formed between endophytes and their host macrophytes can be complex (Correa, 1994;Potin, 2012) and impacted by their environment (Russell et al, 2005;Eggert et al, 2010). Classification of these symbioses range from mutualistic to pathogenic depending on the species involved (Correa, 1994;Potin, 2012), therefore defining these relationships is important to understanding ecosystem processes.…”

“…If endophyte presence results in physiological stress to the algal host as it can in terrestrial plants (Pinto et al, 2000), the photocentres of the host adjacent to endophyte infection could be expected to be less efficient than those further away from infection (photosynthetic parameters would be negatively impacted). In previous studies pulse amplitude modulated (PAM) fluorometry has been used successfully with Antarctic algae to generate rapid light curves (RLCs) using lower irradiances and measure maximum quantum yield (MQY) (Runcie & Riddle, 2006, 2012. From these measurements one can get an accurate calculation of maximum electron transport rate (ETR max ), saturating irradiance (E k ) and the slope to saturation of photo centres (α).…”

“…Macroalgae in subtidal areas of the western Antarctic Peninsula support very high densities of amphipod mesograzers (Richardson, 1971(Richardson, , 1977Huang et al, 2007;Aumack et al, 2011a) and a subsequent study confirmed that mesograzers associated with the chemically defended macroalgal species in the Antarctic subtidal do indeed ablate free-living filamentous algae, selecting for the endophytic habit . Worldwide, research on endophytemacroalgal symbioses has shown that endophytes have varied effects on their hosts (Potin, 2012;Schoenrock et al, 2013). In Antarctic macroalgae, high occurrence of endophyte presence throughout a host thallus has a negative impact on growth in three species and survival in one species of macroalgae, but no impact on another (Schoenrock et al, 2013).…”

“…Classification of these symbioses range from mutualistic to pathogenic depending on the species involved (Correa, 1994;Potin, 2012), therefore defining these relationships is important to understanding ecosystem processes. The high frequency of endophyte presence in many species of Antarctic macroalgae was first noted by Peters (2003) and subsequently quantified by Amsler et al (2009).…”

Life history bias in endophyte infection of the Antarctic rhodophyte, Iridaea cordata

“…Despite molecular identification of brown endophytes and ongoing identification of green endophytes, it is impossible to determine which species drive pathogenicity in the host, I. cordata. In some species, endophyte infection can be considered an infectious disease and be extremely destructive (Fujita et al 1972, Ishikawa and Saga 1989, Potin 2012, removing the host from populations (Goff andCole 1976, Buschmann et al 1997) as well as the pathogen (Toft and Karter 1990). Removal would ultimately decrease the fitness of a host (perhaps as well of the pathogen), but currently there are few studies that translate the effect of endophyte infections to the fitness of the host algae.…”