Chemically mediated resistance to mesoherbivory in finely branched macroalgae along the western Antarctic Peninsula

Tolerance and sequestration of macroalgal chemical defenses by an Antarctic amphipod: a ‘cheater’ among mutualists

“…that, combined with time constraints, they were not in cluded in the May 2011 experiment. The 4 red algal species that were consumed by Paradexamine fissicauda in the 2010 experimentbut were known from previous studies to be unpalatable to other amphipod species because of chemical defenses (Aumack et al 2010) and often also to fish and sea stars (Amsler et al 2005) -were chosen for use in 4-way choice experiments in 2011 and 2012.…”

“…Estimated amphipod densities range up to tens to hundreds of thousands of amphipods per m 2 of the bottom in pure stands of their preferred macroalgal hosts (Amsler et al 2008). Most of the macroalgae, including all of the ecologically dominant taxa, are chemically defended from being consumed by both macrograzers and mesograzers (Amsler et al 2005, 2009a, Aumack et al 2010. Amphipods and other small marine grazers can benefit from associating with chemically defended macroalgae because the algae can provide a refuge from omnivorous macrograzers such as fish (Hay 1992(Hay , 1996.…”

“…Although these Antarctic amphipods do not appear to consume most host macroalgae, they consume large quantities of epiphytic diatoms (Aumack 2010, Aumack et al 2011b) which almost certainly benefits their hosts. Many studies throughout the world have shown that amphipods and other mesograzers can benefit their host macrophytes in this manner by limiting the growth of epiphytic microalgae and/or filamentous algae, which can compete with the macrophytes for light and nutrients (e.g.…”

“…In a survey of the amphipod fauna associated with 8 common macroalgae in our study area, P. fissicauda was 2 to 3 orders of magnitude more abundant on the chemically defended red alga, Plocamium cartilagineum, than on any of the other 7 species (Huang et al 2007). In a study including both amphipod gut content analyses and stable isotope composition, Aumack (2010) found a majority of the gut contents from Paradexamine fissicauda were macroalgal thallus or filaments. The stable isotope composition of P. fissicauda was the only one of 8 common amphipod species examined that closely matched Plocamium cartilagineum or other chemically defen ded red algae.…”

Deterrent activities in the crude lipophilic fractions of Antarctic benthic organisms: chemical defences against keystone predators

“…110 m) may have different chemistry due to the variation in depths or the extraction protocol, which yielded unexpected inactivity. Other algae, like Palmaria decipiens, are more preferred as food (though not for our amphipod) but are not preferred as hosts (Amsler et al 2005;Aumack et al 2010;Bucolo et al 2011). Analogous chemical refuges have not been described in Antarctic sponges, yet some defended species host dense amphipod populations ).…”