Indirect effects of climate change altered the cannibalistic behaviour of shell-drilling gastropods in Antarctica during the Eocene

Abstract

The fossil record from Seymour Island, Antarctic Peninsula, provides a record of biotic response to the onset of global climatic cooling during the Eocene. Using drilling traces—small, round holes preserved on prey shells—we examined the effect of a cooling pulse 41 Ma on the cannibalistic behaviour of predatory naticid gastropods. We predicted that cannibalistic attacks would decline in response to the cooling climate, reflecting reduced activity levels, energy requirements and constraints on the chemically aided drilling process of the naticids. Surprisingly, however, cannibalism frequencies did not change. This counterintuitive result is best explained by a sharp reduction in durophagous (shell-crushing) predation in shallow-benthic communities in Antarctica that also occurred as the climate cooled. Reduced durophagous predation may have created a less-risky environment for foraging naticids, stimulating cannibalistic behaviour. The change in the top-down control exerted by shell-crushing predators on naticids may have counteracted the direct, negative effects of declining temperatures on the predatory performance of naticids. Our results suggest that the long-term consequences of climate change cannot be predicted solely from its direct effects on predation, because the temperature can have large indirect effects on consumer–resource interactions, especially where risk-effects dominate.

Predation in the marine fossil record: Studies, data, recognition, environmental factors, and behavior

“…A recent study highlighted the effect of cooling on predator-prey interactions during the Eocene in Antarctica (Dietl et al, 2018). Unlike their prediction, cannibalistic drilling among naticids did not decrease during the cooling event, but remained stable.…”

Drilling predation on Antarctic tusk shells: first records on Recent scaphopods from the Southern Hemisphere

“…Regarding the gastropods that could have produced the drillholes, and taking into account the infaunal mode of life of scaphopods (either fully buried or with an edge above the substrate) and the presence of P. aureolutea in the same assemblages where the scaphopods with drillholes were recovered, it is interpreted that naticids are the most plausible predators. In Antarctica, previous studies on naticid predation come from the Eocene (see Dietl et al 2018, Harper et al 2019), and there are no other references on extant communities.…”