2015 GSA Annual Meeting in Baltimore, Maryland, USA (1-4 November 2015)

Paper No. 166-11
Presentation Time: 4:30 PM


ROCCA, Alexandra N., MENDONCA, Steven E., WEBB, Amelinda E., SCHNEIDER, Chris L. and LEIGHTON, Lindsey R., Earth & Atmospheric Sciences, University of Alberta, Edmonton, AB T6G 2E3, Canada, arocca@ualberta.ca

Several studies have examined sclerobionts either through time on a global scale, or as case studies focused on sclerobionts from a single bed. However, there has been little investigation into how sclerobiont communities and their hosts change through time utilizing high-resolution sampling through a single stratigraphic series. This research will focus on how sclerobiont communities have changed through time in the Waterways Formation (Givetian-Frasnian, Devonian, Western Canada Sedimentary Basin) of Alberta, Canada to explore the processes (e.g., paleoenvironment, host preference) that may have influenced sclerobiont distribution of one formation over time.

Paleozoic brachiopods were very common hosts to sclerobionts, making them an excellent focus for the study of epibiosis. Over 3300 brachiopods from 35 different species were collected from 26 samples in the Firebag, Calumet, and Moberly members (Waterways Formation). Overall, there were 5094 individual sclerobionts, encrusting 37% of host brachiopods. Microconchus was the most common sclerobiont, encrusting 77% of hosts. We performed Non-metric Multi-dimensional Scaling (NMDS), with a Wisconsin transformation and Canberra distance. Both raw and standardized data were used with little difference between the resulting ordinations.

NMDS first axis scores and the percentage of Microconchus per total sclerobionts for each bed correlated significantly (r = 0.624, p < 0.001). Inspection of the ordination plots revealed that the major shift in sclerobiont communities parallels a similar shift in host communities and an increase in allochems in the sediment during the lower Moberly Member in the upper Waterways Formation. Sclerobiont communities are more diverse in the Firebag and Calumet members of the lower Waterways Formation, while Microconchus comprise > 80% of the Moberly sclerobionts. It is unclear if this is due to preference for particular hosts, for certain environmental conditions, or for some other factor. Regardless, it is evident that sclerobionts, such as Microconchus, are affected by the interplay of environment and host, which encourages further work in exploring these patterns in order to better understand their paleoecology.