Palaeontology Division Talk
Exploring the past, present, and future of predator-prey interactions between crabs and their gastropod prey
Speaker: Kristina M. Barclay, Ph.D. Candidate, Department of Earth and Atmospheric Sciences, University of Alberta
January 17, 2020
Location: Mount Royal University, Room B108
7:30pm: Talk Starts
*CSPG members can register for free and track their CPD hours!
Interactions between predators and prey play an important role in structuring their communities and shaping evolution. However, human-induced climate change has the potential to influence both predators and prey and disrupt their interactions. The fossil record provides an enormous resource to investigate how both past and current climate change has affected organisms, their interactions, and ecosystems. In particular, scars left on prey by failed predatory attacks provide an excellent record, and often the only evidence, of predator-prey interactions in both modern and fossil ecosystems. However, as these wounds, known as repair scars, are records of failed rather than successful attacks, with successful attacks resulting in the destruction of the prey, it can be difficult to interpret whether repair scars signal overall attack rates, or the success/failure rate of the predator. Furthermore, the appearance of a repair scar can be affected by the struc-tural integrity of the prey’s defenses, such as a gastropod shell, as well as prey selection by the predator. Here, shell-crushing crabs and their gastropod prey were used as a model system for exploring potential relationships between prey defenses, prey selection, and repair scars in the past, present, and possible future. Specifically, the goals were to use modern experiments to un-derstand how prey defenses are affected by ocean acidification, a major by-product of carbon dioxide emissions, and to test patterns of prey selection by crabs, and then examine how pat-terns of repair scars in gastropods manifest through both space and time.
First, I tested how gastropod shells by both ocean acidification and predation cues in gastropods Tegula funebralis and Nucella ostrina.
After exposure to decreased seawater pH and/or preda-tion cues for six months, in low pH treatments, both shell growth and strength in T. funebralis was drastically reduced. However only shell strength, and not growth of N. ostrina was impacted by low pH, and not as severely as T. funebralis. Examination of shell composition and micro-structure of both species using microCT scans, XRD analysis, and SEM imaging indicated that the loss of shell strength was from dissolution of the outermost shell layer in both species, with the microstructural arrangement in T. funebralis likely causing more severe dissolution than ob-served in N. ostrina. Patterns of crab prey selection between three species of the gastropod Nu-cella were then examined to understand how crabs attack and select prey. The experiment re-vealed that crabs are most likely to attack the first gastropod they detect, with a preference for the larger species most likely driven by their inability to always recognize smaller prey. I then ex-plored patterns of repair scars in T. funebralis both geographically along the modern west coast of Canada and the U.S., as well as temporally between the Late Pleistocene and modern of southern California. By measuring the size at which repair scars occur, we are better able to dis-tinguish between the number of attacks and potential differences in failure rates of crabs. Crab predation in the modern also showed strong regional variation along the west coast, with the low-est number of attacks in southern California. Furthermore, comparisons of modern and fossil repair scars in southern California indicated that there are fewer crab attacks today, suggesting that crab populations may already be affected by human activity. By studying how prey defens-es, prey selection, and repair scar systems manifest, we can explore how predator-prey relation-ships have changed both in the past and present, and how they may continue to change due to our current climate crisis.
Kristina Barclay grew up in Saskatchewan, completing both her B.Sc. and M.Sc. in paleontology at the University of Alberta studying the functional morphology and palaeoecology of Devonian brachiopods and their encrusting organisms. She is currently finishing her Ph.D. studying preda-tor-prey relationships between crabs and gastropods at the University of Alberta under Dr. Lind-sey Leighton, and will be defending her dissertation in early January, 2020. She also held a Vani-er Canadian Graduate Scholarship that allowed her to spend a year working with Dr. Brian Gay-lord (UC Davis) at Bodega Marine Laboratory in California studying ocean acidification and bio-mechanics in modern marine invertebrates. In addition to her research interests in marine inver-tebrates, palaeoecology, predation, and ocean acidification, Kristina is a strong advocate for sci-ence outreach and education, and has spent several years working in museums and science centres in Saskatchewan and Alberta.
In addition to the main presentation by Kristina Barclay, Dr. Leslie Eliuk will provide a brief presentation.
Museum of the Rockies (MOR), Bozeman Montana – A Paleobiolog-ical Dinosaur Emporium.
Speaker: Dr. Leslie Eliuk, Semi-retired Exploration Geologist and APS Member
MOR in the university city of Bozeman Montana was visited in the Spring of 2019 and greatly enjoyed for a wizard display of meat-eating Tyrannosaurus rex and plant-eating triceratops sp. of the Late Cretaceous ranging from egg to oldster, or at least BIG. Reportedly it contains the greatest number of dinosaur specimens in one archive mainly from the areas badlands and sup-posedly the world’s largest T.rex (maybe just surpassed by the new Saskatchewan recovery just put on display in Regina). There are also sections on local culture especially Plains natives & pioneers and a planetarium (google the Museum for a very well-illustrated website). But what will be discussed and illustrated are the displays on dinosaurs that made use of a fascinating tech-nique of half life-size display of the bones of the beasts on one side and on the other side the dis-play an interpretation of the flesh and colourful feathers (or not) in its habitat. The history and ecology of many ages and types of dinosaurs are there to be enjoyed. This was the museum where the legendary Jack Horner (model for vertebrate paleontologist hero of Jurassic Park movies) hailed from and where he encouraged Dr. Mary Schweitzer to search for dinosaurian blood DNA.
A reporter-visitor, Dr. Leslie Eliuk is a GeoTours Consultant and semi-retired former Shell Cana-da exploration geologist, 1969-1999. After nearly a decade at Dalhousie University, he graduated with a PhD in 2016 on the Jurassic-Cretaceous carbonate platform by the major Sable Delta.