PRODUCTION OF SECONDARY METABOLITES BY FILAMENTOUS TROPICAL MARINE CYANOBACTERIA: ECOLOGICAL FUNCTIONS OF THE COMPOUNDS

Abstract

Cyanobacterial blooms are becoming more common in many reef habitats. The broadly acting feeding deterrent compound ypaoamide, produced by a mixed cyanobacterial assemblage, has been linked to bloom formation and mass fish die‐offs ( Siganus argenteus and Siganus spinus ) in Guam. Specific metabolites produced by Lyngbya majuscula Gomont act as both feeding attractants to the specialist herbivore Stylocheilus longicauda , and as effective feeding deterrents to generalist fishes. Two‐dimensional TLC (2D‐TLC) analysis of cyanobacterial crude extracts was used to select chemically distinct populations (chemotypes) of bloom‐forming filamentous cyanobacteria for chemical and ecological evaluation. Crude extracts produced by different species, chemotypes, and chemically distinct Micronesian marine cyanobacterial assemblages deter feeding activity of generalist reef herbivores. The ecological function of cyanobacterial secondary metabolites, especially as related to diversity of compound production and the relationship of metabolite production to bloom formation is discussed.