METHODS USED TO EXAMINE ENCRUSTATION: WHAT WORKS WHEN?
Select Paleozoic sclerobiont-bearing brachiopods were examined following a variety of methodologies. Methods used to collect sclerobiont abundance include encrustation frequency, numerical abundance of taxa, and areal abundance (% cover) of taxa. Spatial patterns of encrustation were collected by partitioning regions (6, 9, 13, and 32) on an idealized host shell and counting the occurrence of each taxon within a region, estimating areal % cover of each taxon and sketching the location on an idealized outline of the host, or photographing the host shell and using ArcGIS to map the location of each taxon.
Ranking sclerobionts according to areal % cover of the host allows colonial and solitary encrusters to receive similar weight and was chosen as a baseline. The rank position of ~ 20% of taxa ordered by numerical abundance changed significantly (>4 places), and 30% of taxa ranked by their encrustation frequency on host shells did the same. Colonial and solitary organisms were both impacted in rank order. Spatially, 6 and 9 region partitions fairly reflect the number of sclerobionts observed in the sample but 13 and 32 region partitions significantly over-represent them. 13 and 32 region partitions also significantly under-represent the number of sclerobionts observed along the commissure of hosts, which is particularly interesting as increased partitioning would presumably increase precision. Understanding the biases in the varied methodologies will allow more highly resolved interpretations among previous studies and enhance analysis in future work.