Algal symbiosis, and the collapse and recovery of reef communities: Lazarus corals across the K–T boundary

Abstract

INTRODUCTION It has long been customary to consider the ecology of corals in terms of reef and non-reef groups. Yonge's (1940) landmark review also emphasized the critical role of algal symbiosis in the ecology of modern reefs and reef corals, and this view has since been reinforced by numerous other authors. This in turn has influenced perceptions of ancient reefs, and more recently it has generated a series of important reviews specifically relating patterns of reef-building through geological time to the history of algal symbiosis in corals and other reef organisms (e.g. Cowen, 1988; Talent, 1988; Copper, 1989; Stanley, 1992; Wood, 1993; 1995; Stanley & Swart, 1995). As part of this, intervals of reef absence in the geological record are attributed by some to collapse ( sic ) of algal symbiosis. Alongside this, most of these authors have also accepted and furthered the idea first expressed by Newell (1971) that the pattern of reef communities through time has consisted of relatively stable ‘packages’, punctuated by phases of short-term, rapid change, mediated by global events (see also Boucot, 1983; Heckel, 1974; James, 1983; Sheehan, 1985; Fagerstrom, 1987; Jackson, 1992; 1994; Kauffman & Fagerstrom, 1993). Hallock and Schlager (1986) added an extra strand to these arguments by suggesting that, since modern reef corals, reefs and algal symbiosis are adversely affected by nutrient-rich (eutrophic) waters, fluctuating patterns of reef occurrence on various geological timescales might also be controlled by regional to global fluctuations in nutrient levels.