Effects of herbivory and the season of disturbance on algal succession in a tropical intertidal shore, Phuket, Thailand Jaruwan Mayakun, 1 Jeong Ha Kim 2 and Anchana Prathep 1, * 1 Seaweed and Seagrass Research Unit, Excellence Centre for Biodiversity of Peninsular, Thailand, Department of Biology, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand, and 2 Department of Biological Science, Sungkyunkwan University, Suwon 440-746, South Korea SUMMARY The effects of herbivory and the season of disturbance on species composition and algal succession were experimentally tested at a tropical intertidal shore, Phuket Island, Thailand. Dead coral patches were cleared of all organisms during both the dry and rainy seasons in order to study the effects of season on algal succession and cages were set up to exclude fish herbivory. Algal succession in this intertidal habitat showed a simple pattern and took a year from the early Ulva paradoxa C. Agardh stage to the late Polysiphonia sphaerocarpa Børgesen stage. The abundance of algae during succession was under the influence of seasonal change. U. paradoxa reproduced and recruited through- out the year. Caging effects did not apparently influence algal abundance, perhaps because resident herbivorous damselfishes excluded other herbivores from their ter- ritories and maintained their algal “farms”. Unexpect- edly, the percent cover of Ulva in the caged plots was lower than in uncaged plots. This pattern may indicate that caging excluded damselfishes only, but allowed small herbivores that consumed substantial amounts of soft filamentous algae in the cages. Key words: algal succession, cage experiment, her- bivory, season of disturbance. INTRODUCTION Disturbance and the patterns of recovery from distur- bance can be critical factors that determine the vari- ability in community structure (Kim & DeWreede 1996). Natural disturbance events often produce patches of cleared space, which eventually recover and re-establish a balance of species in a community (Dayton 1971; Sousa 1979a, 1984b). The pattern of community succession varies both in space and time depending not only on the characteristics of the distur- bance but also on the life-history traits of the species involved and their particular vulnerabilities (Sousa 1984a, b; Benedetti-Cecchi & Cinelli 1993). For example, the timing of disturbance can also have significant effects on algal abundance and colonization (Sousa 1979a, 1984b; Foster et al. 2003) because of the seasonal availability of propagules (spores or veg- etative buds) of certain species (Foster 1975; Paine 1977; Emerson & Zedler 1978; Sousa 1979a; Hawkins 1981; Dayton et al. 1984; Breitburg 1985; Kennelly 1987; Benedetti-Cecchi & Cinelli 1993; Kim & DeWreede 1996). Such initial variability may influence subsequent colonization, so that the gaps created in different seasons become dominated by different organisms in later succession stages (Jara & Moreno 1984; Kim & DeWreede 1996). Herbivory directly and indirectly influences algal abundance, succession and species dominance (Sousa 1979b; Benedetti-Cecchi & Cinelli 1993; McClanahan 1997). Herbivorous fishes are capable of maintaining the diversity of benthic algae (Kennelly 1983; Sam- marco 1983; Carpenter 1986; Lewis 1986; Mcclana- han et al. 1994; Hixon & Brostoff 1996; McClanahan 1997; Ferreira et al. 1998). Effects of herbivory on algal succession have been demonstrated; however, the effects are not always consistent spacially. Most studies on disturbance and succession in marine habitats have been conducted much more frequently on temperate rocky shores, whereas tropical rocky shores and inter- tidal zones remain largely unexplored in terms of dis- turbance effects. Some research on herbivory and algal succession on coral reefs and subtidal zones has been published (Hixon & Brostoff 1996; McClanahan 1997); however, additional research is still needed to under- stand the effect of herbivory on algal successional pat- terns within the tropical intertidal zone. Experimental studies of the relative importance of herbivorous fish and the season of clearing on algal succession have traditionally been conducted in sub- tidal coral reef habitats. Compared with relatively large *To whom correspondence should be addressed. Email: anchana.p@psu.ac.th Communicating editor: J. West. Received 5 December 2008; accepted 5 September 2009. doi: 10.1111/j.1440-1835.2010.00566.x Phycological Research 2010; 58: 88–96 © 2010 Japanese Society of Phycology