SIMILARITIES BETWEEN BENTHIC CYANOBACTERIA AND EUKARYOTIC ALGAE: CHEMICAL DEFENSES AND THE ANIMALS WHO LOVE THEM

Abstract

Cruz‐Rivera, E.University of Guam Marine Laboratory, UOG Station, Mangilao, GU 96923, USAAbout 400 compounds have been isolated from marine cyanobacteria worldwide, but their ecological roles remain largely unknown. In the coral reefs of the tropical Pacific, large filamentous cyanobacteria are common components of the benthic community. Many of these benthic cyanobacteria produce secondary metabolites that serve as chemical defenses against large grazers. However, diverse small consumers have evolved to cope with cyanobacterial metabolites and preferentially use cyanobacterial mats as food and shelter. While studies have focused mainly on the negative effects of cyanobacteria on benthic communities, the positive roles of cyanobacteria for benthic animals have rarely been addressed. Interactions between filamentous cyanobacteria and their associated fauna are diverse and include sequestration of cyanobacterial metabolites by gastropods, facultative and specialized consumption of cyanobacteria by grazers, temporary shelter for small predators, and symbiosis between cyanobacteria and some crustaceans. Although examples of similar interactions between chemically‐defended eukaryotic algae and their associates are known, these interactions have not been previously addressed for cyanobacteria. The number of organisms that preferentially associates with benthic filamentous cyanobacteria suggests that these prokaryotes can significantly influence local biodiversity patterns. This research indicates strong parallels on the ecology and evolution of consumer‐prey interactions between eukaryotic and prokaryotic algae in coral reefs.