The role of modern and fossil cyanobacterial borings in bioerosion and bathymetry

Abstract

Measurements on modern coral reefs at Lee Stocking Island(Bahamas) illustrate that boring cyanobacteria species make a major contribution to microboring bioerosion rates. Borings attributed to cyanobacteria also occur in fossil environments. Bioerosional studies on Permian and Triassic reefs show similar intensities to those observed on modern equivalents. The importance of borings assigned to cyanobacterial activity is even more apparent in paleobathymetry. Comparison of the bathymétrie ranges known from modern and fossil microborings demonstrates a preference of boring cyanobacteria for shallow marine environments. Furthermore, some traces are linked to distinct portions of the shallow euphotic zone. They significantly contribute to characterize typical microboring assemblages, which are used for paleodepth reconstructions. In contrast to these stenobathic species, one cyanobacterial species turned out to be eurybathic. It has been recorded as deep as the dysphotic zone but may even extend to the aphotic zone.

Microendoliths of the Shallow Euphotic Zone in open and shaded habitats at 30°N – Eilat, Israel – paleoecological implications

“…Single traces follow an independent ichnotaxonomy (Bertling et al 2006) and as trace communities (ichnocoenoses) they can be used as paleo-depth indicators in fossil basins (Vogel et al 1987;Radtke 1991;Glaub 1994;Balog 1996;Hofmann 1996;Plewes 1996;Bundschuh 2000;Vogel and Marincovich 2004). Five photic zones are distinguished on the basis of depth-specific ichnocoenoses (after Glaub 1994;Glaub et al 2001): The Shallow Euphotic Zones (SEZs) II and III, the Deep Euphotic Zone (DEZ), the Dysphotic Zone (DZ) and the Aphotic Zone (AZ). These zones are viewed as indicative for paleophotic zones rather than absolute paleo-depths (Perry and Macdonald 2002).…”

Microendoliths in Lower Pliocene Oysters from the Alt Empordà Basin, NW Mediterranean: Paleoenvironmental Inferences

“…In fact, the scarcity of cyanobacteria is relevant because most modern cyanobacteria prefer shallow waters where the light intensity is higher, and they diminish with lowering light. Therefore, cyanobacterial borings dominate the shallow euphotic zones, while their presence decreases in the deeper euphotic zone (Glaub et al, 2001).…”

Palaeoenvironmental significance of cool-water microbialites in the Darriwilian (Middle Ordovician) of Sweden

“…Different micro‐endolithic biocoenoses and ichnocoenoses have repeatedly been shown to reflect depositional depth, mainly through their relation to light (see Perkins & Tsentas ; Budd & Perkins ; Glaub et al . , ; Radtke & Golubic ; Wisshak et al . , ; Vogel & Brett ).…”

“…Regardless of oncoid producers, the notable presence of micro-endolithic borings provides important clues to the depositional environment. Different micro-endolithic biocoenoses and ichnocoenoses have repeatedly been shown to reflect depositional depth, mainly through their relation to light (see Perkins & Tsentas 1976;Budd & Perkins 1980;Glaub et al 2001Glaub et al , 2002Wisshak et al 2005Wisshak et al , 2011Vogel & Brett 2009). Thus, the identification of endolithic ichnotaxa can provide an important tool for the interpretation of depositional depth.…”

“…The predominance of borings oriented perpendicular to laminae and rims strongly indicates a shallow depositional environment within the photic zone, as prostrate (along-surface) borings dominate in deeper dysphotic and aphotic waters (e.g. Budd & Perkins 1980;Glaub et al 2001;cf. Podhalańska 1984).…”