Chemical Ecology and Marine Biodiversity: Insights and Products from the Sea

biodiversity on the genetic, species, and ecosystem levels.TREMENDOUS ATTENTION has been focused on the loss oK and threats to, terrestrial biodiversity.Until very recently (Norse, 1993), much less attention was devoted to marine biodiversity despite the fact that marine systems are larger, older, have a huge impact on global climate, and support nearly twice as many phyla of animals as do terrestrial systems (see Table 2-2 in Norse, 1993).Our reduced attention to marine biodiversity reflects our relative ignorance of marine systems rather than their lack of importance to humans or to the ecosystem functions on which virtually all terrestrial life depends.Humans have spent thousands of years in intimate association with terrestrial biota, but only a few decades using SCUBA and submersibles to explore the world's oceans.In this article we discuss how chemically mediated interactions affect mafine biodiversity and consider the insights that can be gained from understanding the mechanisms involved in these interactions.Biodiversity is often used incorrectly as a synonym of species diversity; however, biodiversity also encompasses genetic and ecosystem diversity (Norse, 1993).The factors that produce and maintain patterns of biodiversity at these different levels are complex and poorly understood.In this review, we argue that secondary metabolites produced by a variety of marine organisms as defenses against consumers, pathogens, and competitors {Hay and Steinberg, 1992: Paul, 1992) can have important complex or indirect efl'ects that alter marine biodiversity on the genetic, species, and ecosystem levels.The role of biogenic structural complexity in affecting species diversity has been extensively studied and is broadly appreciated in both marine and terrestrial communities (Ehrlich and Roughgarden,