In summer, the fish appear and remove the palatable species, leaving the flora dominated selleck kinase inhibitor by unpalatable brown algae, which are the only refuge for mesograzers (Hay 1986, Hay and Sutherland 1988, Duffy and Hay 1994). In the two tropical systems, levels of predation on macroalgae and mesograzers are high throughout the year (Hay et al. 1989, 1990). The temperate reefs studied by Taylor and Steinberg (2005) differed in having higher diversity of both macroalgae
and mesograzers, far less seasonal fluctuation in composition of the flora than North Carolina, a predominance of carnivorous rather than omnivorous fish, more large non-fish grazers compared to North Carolina, and qualitatively different chemical defenses in many of the dominant macroalgae, which, on the Australasian reefs, are predominantly fucoids and kelps. Importantly, grazing intensity on the macroalgae is much patchier in the Australasian reefs compared to North Carolina or the tropics, so palatable macroalgal species can persist in spatial refuges where grazing intensity is low (Taylor and Steinberg 2005). Taylor and Steinberg
(2005) reported that following predictions based on Hay and Duffy et al., LY294002 in vivo most mesograzers they studied did prefer to eat the hosts they were most commonly collected on and that most of these hosts were relatively less palatable than others to larger consumers. However, macroalgal species that were less palatable to larger consumers did not support larger densities or more species of mesograzers overall compared to palatable species, although mesograzer species evenness was greater on the unpalatable
macroalgae. Exoribonuclease Mesograzers can also benefit macroalgal hosts in other ways. For example, Stachowicz and Whitlatch (2005) reported that snails benefit their hosts by consuming epiphytic invertebrates and in turn benefit under some circumstances by an associational refuge from predatory crabs. In nutrient-limited environments, macroalgae can benefit from the nitrogen excreted by associated invertebrates (e.g., Bracken et al. 2007, Guidone et al. 2012). Over the past 13 years, our research group has been investigating the chemical ecology of macroalgal–invertebrate interactions in macroalgal-dominated communities along the western Antarctic Peninsula. We have come to recognize that macroalgal–mesograzer interactions are very important here and are similar in many ways to those described previously in temperate and tropical regions. However, the macroalgal communities differ in important ways from those lower latitude regions where macroalgal–mesograzer interactions have been studied previously and there are corresponding differences in the nature of the interactions of macroalgae and mesograzers. Mesograzers in these communities also appear to have selected for a relatively high frequency of filamentous endophytes growing within the larger macrophytes.