Macroalgal chemical defenses and their roles in structuring temperate marine communities

Abstract

Temperate zone macroalgal communities in general and littoral communities in particular consist of a diverse producer assemblage, a rich mesograzer fauna occasionally complemented with larger herbivores, and predators. Diversity in the producer assemblage is generated by small-scale heterogeneity in substrate characteristics, seasonal variation in growing conditions, and the depth gradient. Abiotic disturbances, mainly in the form of wave energy, counteract competitive exclusion, thereby enhancing species richness (Sousa 2001). The diverse producer assemblage comprises a habitat and food resource for a species-rich fauna (reviewed in Underwood 2000; Menge and Branch 2001). In such a diverse community, interactions within and between trophic levels become important for the regulation of the structure and function of both the producer and consumer assemblages (Duffy 2002; Worm and Duffy 2003).