Predator–prey interactions among Pliocene molluscs from the Tjörnes Peninsula, Iceland; across the trans-Arctic invasion

• Main Authors: Kelley, Patricia, NC DOCKS at The University of North Carolina Wilmington
• Language: English
• Published: 2021
• Subjects: Arctic; Tjörnes; Iceland
• Online Access: http://libres.uncg.edu/ir/uncw/f/kelleyp2021.pdf

The fossil record provides a long-term perspective to better understand the impacts of species invasions in their environmental contexts. Temporal analyses of predator–prey interactions from the Tjörnes deposits, Iceland, track naticid gastropod drilling predation across the trans-Arctic invasion (TAI: ~3.5?Ma). These deposits represent three zones subdivided into 25 marine fossil-bearing beds that correspond with the stages of invasion: Tapes (1–5) and Mactra (6–12) zones are pre-invasion, whereas the Serripes zone (13–25) represents the invasion. Bivalve and naticid gastropod specimens were analysed from the Bárðarson (1925) samples at the Icelandic Institute of Natural History, which consisted of pre-invasion and invasion samples; we also bulk-sampled the Serripes zone. Height and length of specimens were measured to assess size changes, and the occurrence of complete and incomplete drill holes and drill hole diameter were recorded for whole bivalves and naticids. Drilling frequency (DF) and prey effectiveness (PE, the incidence of failed drilling) were calculated to track predator–prey interactions. Genus-level diversity increased through the Tjörnes deposits, in part related to a shift from intertidal to sublittoral environments. DF increased and PE decreased significantly between the pre-invasion and Serripes zones. However, DF decreased from the early to the late Serripes zone, which could signify stabilization of the Tjörnes community. An increase in competition among predators through the invasion is supported by an increase in abundance of naticids relative to bivalves, especially invasive species, a switch to smaller-sized bivalve prey, a decrease in naticid mean size and an increase in confamilial predation.