A palaeontologist’s guide to modern marine ecology

Kristina here – 

Interdisciplinary experiences are a great way to learn new things and broaden your perspectives as a scientist. I’m a palaeontologist who studies the effects of climate change on predation and biotic interactions in marine invertebrates, but over the course of my research career, I’ve spent more time working with modern animals and ecosystems than I have with fossil ones. It may sound strange, but I believe it’s made me a better palaeontologist. I’ve learned a lot from working with modern ecologists, and I’d highly recommend it to any aspiring or established palaeontologists.

Why work with modern systems?

Predation in action – a giant seastar eating a giant clam (Bamfield Inlet, B.C.)

Observing animals helps you understand the mechanisms of what you might observe in the fossil record. You also really gain an appreciation for the things that don’t fossilize, like animal behaviour (I’ve been outsmarted by crabs, and maybe a snail or two, on more than one occasion). I study predation and biotic interactions, which are not possible to observe in real time in the fossil record because those animals have been dead for a very long time. Instead, we as palaeontologists must rely on other clues, like predation scars, as evidence that organisms interacted. But interpreting how or why organisms interacted in the fossil record can still be tricky. For example, crab predation on molluscs has been common since the Mesozoic, but as crabs crush their prey into oblivion to eat, the only evidence of crab predation we can observe in the fossil record are failed attacks where the prey survived and a scar formed on its shell. A big question in palaeontology has therefore been: do these failed attacks we observe in the fossil record actually tell us anything about predation? Conducting live experiments and modern field work where we observe how crabs prey upon animals like snails helps us understand what we are seeing in the fossil record and why. For example, one thing we’ve learned is that the number of crab scars on snails reflects the abundance of crabs at a locality rather than changes in how successful crabs are at killing snails between sites (Molinaro et al. 2014; Stafford et al. 2015).

Collecting snails for lab experiments (Bodega Marine Lab)

We can use modern experiments as baselines that can “calibrate” our interpretations of patterns in the fossil record. Part of my Ph.D. research involved conducting a long-term ocean acidification experiment on two species of snails at Bodega Marine Laboratory. I wanted to know how ocean acidification and predation affected snail shell growth and strength, and what this might mean for both past and future predator-prey interactions between crabs and snails. I found that some shell materials are more vulnerable to ocean acidification because they grow less and become weaker, and are therefore more susceptible to predation (Barclay et al. 2019). Not only does this mean that some mollusc species might become more vulnerable to predation with continued climate change, but it means that we can use clues like this to help identify periods of ocean acidification in the fossil record, and then watch how it plays out in ecosystems over time.

Metrhom Robo-titrator (determines water alkalinity) and Instron (measured the force required to crush my shells – very stressful after 6 months of growing them) (Bodega Marine Lab)
My study species – the red rock crab (Cancer productus) and black turban snail (Tegula funebralis) – Notice the crab predation scar on the top right snail)

Comparing modern and fossil systems is important for conservation efforts. There is an entire field of palaeontology called conservation palaeobiology where we try to use deep time perspectives to answer questions related to modern climate change and conservation issues. For another part of my Ph.D. research, I compared crab predation on snails in the same modern and fossil systems to try and understand what has happened to these systems over time. Some of my results have been a little scary, and suggest that human activity has already had major consequences on crab populations in places like southern California.

And, if I’m being perfectly honest, it’s just plain fun to work in modern marine biology! I’ve been lucky enough to travel to many beautiful field sites along the west coast of Canada and the U.S. to conduct research on rocky-intertidal invertebrates. My favourite field sites I’ve been to are on Vancouver Island (near Bamfield, B.C.) and the north-central Oregon coast. I’ve also had the great privilege to conduct research and take classes at three marine labs: Bamfield Marine Sciences Centre on the west side of Vancouver Island, Friday Harbor Laboratories on San Juan Island, Washington, and Bodega Marine Laboratory in northern California. If you ever have the opportunity to conduct research or take classes at any of these places, I’d highly recommend it, and would happily provide some connections and potential funding sources. There’s nothing like some salty sea air, observing live critters in their natural habitats, and the occasional curious seal or whale sighting to inspire your curiosity and love of the natural world. 

Bamfield Sunset at the Bamfield Marine Sciences Centre.

What I’ve learned?

Shelfie with a red abalone (Bodega Marine Lab)

Working with modern ecologists has been such a rewarding experience. I’ve learned so much about animal behaviour, chemistry, and physiology (fun fact: crabs are ridiculously stubborn and will spend hours trying to break into a snail before admitting defeat and throwing the snail across the tank in a tantrum). I’ve also learned a lot of about the world of larvae and plankton (I even got to participate in an experiment with larvae of an endangered species, the white abalone), and seaweeds (which is not something that we often get to see in the fossil record). I also learned a lot of lab, statistical, and experimental design techniques, such as how to analyse water samples for alkalinity and pH. The level of detail and complexity available in live systems can really help you tease apart how such things might influence your interpretations of the fossil record. One of the most interesting things I learned from a lab mate at Bodega Marine Lab was just how much night/day variation there is in tidepool water chemistry, with pH swings of several orders of magnitude in a 24 hour cycle (Jellison et al. 2016)! I also learned that some snails can tow several hundred times their body weight, possibly placing them as one of the strongest animals on earth!

Tidepools at Yaquina Head, Oregon

What can geoscientists offer?

Even though I’ve learned so many new things about modern marine ecology, there are several unique perspectives I’ve been able to offer to my modern marine colleagues as a geoscientist. First, as palaeontologists, our perspective of time and evolution is often completely different than an ecologist’s. One isn’t inherently better or worse, but a geological understanding of time can help you ask big picture questions and allow you to fit modern research into a larger context. For example, a long-term study in the modern is usually on the order of years or decades, whereas palaeontological studies span thousands to millions of years. We understand how things like storms, taphonomy, and time averaging might influence our results in a broader way. We also understand just how fleeting today’s conditions are. One other unique perspective is our geological field training – we think in three dimensions, especially when we are out in the field looking at outcrops. When I see a mussel bed, I’m not just thinking about the biology of individual mussels, I’m thinking about how it accumulated, how water conditions change across it, and what might cause it to change over time. I’m not saying ecologists don’t do that, because they do, but it’s just second nature to geoscientists. 

The important thing here is that one field isn’t better than the other, but rather, we all have different strengths or emphases we’ve learned and by combining both modern and fossil perspectives, you can ask really interesting, important questions!

References

Barclay, K., B. Gaylord, B. Jellison, P. Shukla, E. Sanford, and L. Leighton. 2019: Variation in the effects of ocean acidification on shell growth and strength in two intertidal gastropods. Marine Ecology Progress Series 626:109–121.

Jellison, B. M., A. T. Ninokawa, T. M. Hill, E. Sanford, and B. Gaylord. 2016: Ocean acidification alters the response of intertidal snails to a key sea star predator. Proceedings of the Royal Society B 283:20160890.

Molinaro, D. J., E. S. Stafford, B. M. J. Collins, K. M. Barclay, C. L. Tyler, and L. R. Leighton. 2014: Peeling out predation intensity in the fossil record: A test of repair scar frequency as a suitable proxy for predation pressure along a modern predation gradient. Palaeogeography, Palaeoclimatology, Palaeoecology 412:141–147.

Stafford, E. S., C. L. Tyler, and L. R. Leighton. 2015: Gastropod shell repair tracks predator abundance. Marine Ecology 36:1176–1184.

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