Seaweeds in the Antarctic Marine Coastal Food Web

Abstract

Antarctic macroalgae are the basis of marine food webs in most coastal environments, especially the more confined ones such as bays and fjords. Whether through direct consumption or via detritus, their role in maintaining biodiversity is essential. However, their relevance is due not only by direct trophic interactions but also by indirect feedbacks, since macroalgae act as a habitat and refuge for multiple benthic organisms and as a substrate for epiphytic microalgae. Macroalgae also establish relations of exploitative competition, apparent competition, and mutualism. The control over the biomass and diversity of the macroalgae itself does not seem to be due to trophic interactions (top-down control) but rather to competition and diverse abiotic factors such as substrata and light availability or physical disturbances (ice scouring). The extreme connectivity of trophic networks linked to algae and their detritus determines that food webs are robust to local extinctions; however, non-trophic interactions indicate that changes that affect the growth, biomass, and distribution of macroalgae can have dramatic effects on the diversity of their associated fauna and, indirectly, on the networks of consumers of that fauna. In this chapter, we present a detailed description of macroalgae relationship networks and analyze the stability of the Antarctic community using food web theory.