Mapping sclerobiosis: a new method for interpreting the distribution, biological implications, and paleoenvironmental significance of sclerobionts on biotic hosts

Abstract

The use of sclerobiosis as a tool for paleoenvironmental and paleoecological research is undermined by a lack of comparable methods for sclerobiont data collection and analysis. We present a new method for mapping sclerobiont distributions across any host, and offer an example of how the method may be used to interpret sclerobiont data in relation to host orientation. This approach can also be used to assess the suitability of beds and fossil material for paleoenvironmental reconstruction.A sample of 150 encrusted dorsibiconvex atrypide brachiopods were selected from six beds in the Waterways Formation (latest Givetian – Early Frasnian; Alberta, Canada). The dorsal and ventral valves of each brachiopod were photographed. Sclerobiont taxa were mapped onto the photographs, and the maps were used to create stacked images with each of the 25 brachiopod specimens from each bed. Based on the life orientation of dorsibiconvex atrypides, three zones were designated on the host: the post mortem zone, (only available to sclerobionts after death and reorientation of the host); the shaded zone (brachial valve, excluding the post mortem zone); and the exposed zone (ventral valve).Randomization simulation results indicate that all beds likely exhibit non random encrustation patterns, and corroborate the hypotheses that: (1) much of the encrustation occurred while the hosts were alive, and (2) these beds and fossils have experienced little physical reworking or transport and would be suitable for paleoenvironmental analysis. Mapping sclerobionts across hosts can serve as a unifying method to increase the recognition and use of sclerobiosis in paleontological studies.

Sclerobiosis: A Term for Colonization of Marine Hard Substrates

“…Here we propose the term sclerobiosis. While this term has been used recently by some authors (see Schneider, 2013;Barclay, et al, 2015), it has not been formally defined; which is the purpose of the current paper. When studying different aspects of the colonization of living, dead and inorganic hard substrates, and even when we want to establish comparisons of these colonizations across host groups, time, and space, it is useful to have a term that encompasses all these associations between substrates and colonizers.…”

“…While sclerobiont was considered to indicate an encruster attached to abiotic or biotic (whether living or dead) hard substrate, 'sclerobiosis' or 'sclerobioses' appear in the text without indicating a connotation or meaning each of these terms has. Additionally, Barclay et al (2015) mentioned that sclerobiont is an equivalent term to epibiont in modern studies; then sclerobiosis is used without a precise definition. In this study, the criterion seems to be using the term sclerobiosis to distinguish between pre and post mortem encrustation on hosts.…”

“…In this study, the criterion seems to be using the term sclerobiosis to distinguish between pre and post mortem encrustation on hosts. Luci et al (2021) mentioned the term sclerobiosis only once in the text, probably in the same sense as Barclay et al (2015). Last, Shiino and Tokuda (2016) used the terms sclerobiont and sclerobiosis as keywords, but only used the terms epibiont and epizoan within the text to refer to colonization of living and dead skeletal substrates.…”

Temporal dynamics of encrusting communities during the Late Devonian: a case study from the Central Devonian Field, Russia

“…In the Paleozoic, brachiopods were a common constituent of benthic communities in shallow-water marine environments (e.g., Baliński and Racki 1981; Clapham et al 2006). Because brachiopod shells often served as secondary hard substrates for various epibionts, they have been a frequent subject of encrustation studies (e.g., Alvarez and Taylor 1987; Bordeaux and Brett 1990; Lescinsky 1995; Barclay et al 2013, 2015; Schneider 2013; Zatoń and Borszcz 2013), although encrustation patterns are documented more extensively for Paleozoic brachiopods relative to Mesozoic, Cenozoic, and Recent species (Barnes and Peck 1996, 1997; Bitner 1996; Rodland et al 2004, 2006, 2014), likely due to the post-Paleozoic decline in ecological importance of brachiopods (e.g., Clapham et al 2006; Clapham and Bottjer 2007; Manojlovic and Clapham 2014). While encrustation patterns of Devonian brachiopods have been analyzed frequently in general terms, the dynamics of the encrusting organisms across the stages are poorly known and have never been investigated in detail, especially on uniform substrates.…”