Our article on how eutrophication and hypoxia affect the species and functional diversity of marine bivalves is now available open access in the journal Continental Shelf Research (here). Here's a thread about our study and the individuals who contributed to it.

Anthropogenic nutrient pollution and hypoxia are growing challenges globally. Understanding how these combined stressors affect species and functional diversity is important for anticipating future changes in coastal ecosystems and for establishing appropriate management targets. Unfortunately, few regions have biomonitoring programs that were started before anthropogenic eutrophication. To address this limitation, scientists often use a space-for-time approach, comparing populations in areas characterized by different environmental conditions as analogues for past or future conditions.

For our study we focused on the northern Gulf of Mexico, a region that includes the second largest dead zone in the world. We collected live bivalve mollusks from samples of seafloor sediment at 15 subtidal stations that span more than 600 km of continental shelf habitat. In the northern gulf, higher productivity and lower oxygen concentrations occur offshore of larger watersheds like the Mississippi River and Mobile Bay, in contrast with coastal regions influenced by much smaller watersheds (e.g., the Panhandle of Florida) which have lower productivity and normoxic conditions.

We identified to species ~1500 individual bivalves in our samples and characterized them based on their functional traits (i.e., feeding, mobility, fixation, life position relative to the sediment-water interface, & individual body size). We compared species & functional diversities at a standardized sampling coverage with regional environmental conditions and found higher diversities in less eutrophic settings characterized by normoxic conditions. Diversities declined in eutrophic and hypoxic environments and shifted from abundant suspension feeders to mostly deposit/mixed-feeders. Hypoxia-tolerant, organic-loving bivalves increased in body size in these settings due to greater food, +/or reduced competition/predation.

My lab group collected these samples in 2018 with support from the National Science Foundation and the National Academies' Gulf Research Program. It was the 1st field season supported by my CAREER grant and it was a dream come true to do this work alongside such curious, engaged, & positive undergraduate research students. This research would also have never been possible without the contributions of the vessel captains, crew, & technical support staff that we work with at the following marine labs in the gulf coast: LUMCON, DISL, and FSUCML.

I went through the tenure process at my former institution during the academic year following that field season (2018-2019). I was anxious about whether I would be able to keep my job, and also anxious about whether receiving tenure would limit my opportunities to go elsewhere. I found great solace that year in going to the lab and collecting data on the species that we had sampled, often with a soundtrack of summer fieldwork faves blasting in the background; it engaged my thoughts in a way that I was immensely grateful for.

The challenge was that I was unfamiliar w/ many of these species. I spent countless hours working out how to ID them, and to chronicle this and crowd-source my malacological challenges, I posted species pics tagged #NameThatBivalve to twitter. My colleague, Katie Collins consistently came to the rescue! Katie was doing a postdoc at the University of Chicago and we often found ourselves in our labs/offices at the same time of night. They were generous with their expertise and encouraging, and it was invaluable for me to have another set of eyes (albeit virtually) on these specimens.

In fall 2019 I interviewed for the position I currently hold at Colgate and flew to Okinawa for a biodiversity workshop organized by Moriaki Yasuhara and Yasuhiro Kubota. That meeting led to a number of collaborations, including this one with Anne Chao and Marina Rillo. Anne (jokingly?) told the group in Okinawa that analyzing data was her hobby and to be in touch if we had projects to discuss. At the meeting, I also talked a lot with Marina Rillo, a postdoc working with Helmut Hillebrand, about her research on community structure and space-for-time comparisons.

Fast forward through my family's move to upstate New York in 2020, through the setting up & unpacking of my lab during COVID, resuming & completing data collection for our 2018 live samples, etc. I reached out to Anne, Katie, and Marina about collaborating on this project. Anne is based at National Tsing Hua University in Taiwan, Katie is at the Natural History Museum in England, and Marina is at University of Oldenburg in Germany. Timing of zoom meetings was not always straightforward but discussing our work together was such a treat for me. Each of us brought complementary insights, including coverage-based methods for diversity analysis, molluscan functional traits & taxonomy, environmental measures and their relation to community structure, etc. People showed up, followed through, and taught each other. It was great. As we prepared our manuscript, I asked also Lena, my 17 year old kid, to contribute. Lena is a talented artist and helped us by drafting the block diagram that we used in Fig 1 which illustrates the differences between taxonomic & functional diversity; it was so much fun working on this with them.

I am pleased to share our work and grateful to all of these folks for their contributions. Our manuscript is available here (https://sciencedirect.com/science/article/pii/S0278434324001699); all code & data have been submitted to dyrad & zenodo & will be available soon (https://doi.org/10.5061/dryad.4tmpg4fhk; https://doi.org/10.5281/zenodo.10080545).

Guest post by Madison Cammarata ('26).

As the Spring 2024 semester drew to a close, my anticipation soared for the upcoming adventure awaiting me: joining fellow students and Professor Harnik in his Paleo Lab. Stepping into this new experience was exhilarating, unlike anything I had ever encountered. Despite the warnings from Professor Harnik about grueling 12-hour days under the sun, unpredictable boat rides, and the looming threat of seasickness, I approached it all with unwavering determination.

Guest post by Lindsay Kosnick ('27).

As our group embarked on the long journey to the Gulf, my excitement began to grow. I couldn’t wait to begin my first research experience by getting hands on in the field. I knew there were so many interesting critters and bivalves that could be scooped up and dropped onto my waiting tray. But when we finally got on the boat and things started rocking, everything went downhill. My only experience with boats was on quiet ponds and lakes, so I had no idea that I would get incredibly seasick. No matter what I did or what medication I took, I couldn’t seem to get over it. I spent my days in the field fighting my nausea inside the boat’s cabin and running to the deck to throw up. I couldn’t sit up without feeling sick, let alone work through the samples we were collecting. Needless to say, it wasn’t the trip that I was expecting.

Despite my experience being an unpleasant surprise, I still think it was incredibly valuable that I went on the trip. As a rising sophomore, my future is uncertain. I don’t know exactly what I want to do or where I plan to go. There are so many paths to take within Geology, it’s hard to know which one to follow. Throwing up over the side of the boat may not sound like an experience that would provide me any clarity, but it was. Now I know that marine field work may not be for me. I also know that I want to try other field work, just with my feet firmly on the ground.

Most importantly, my time on the boat has made me even more excited to get started in the lab. Because of the severity of my seasickness, I was really limited on how involved I could be in the field. Now that we are back in the lab, I can’t wait to finally get to work. Over the next few weeks I’ll be taking a close look at various species and their larval shells. When I find a species that is abundant both live and dead with well preserved larval shells, I’ll be able to work on studying its life history. I’m looking forward to seeing where the lab work takes me.

Guest post by Rob Vanderhoef ('27).

First, I had never traveled to the Deep South. The fieldwork allowed me to see rural and wetland parts of Louisiana and the chance to see one of our nation's historical cities, New Orleans. Louisiana was much hotter than I anticipated. However, I drank lots of water and applied lots of sunscreen. I also made sure to consume lots of motion sickness medicine before going out each day, and thankfully, I did not throw up the entire trip!

Dauphin Island, Alabama, was similar to Louisiana, with both locations showing me more about the Deep South than I previously knew. However, our Dauphin Island experience was more uncertain than Louisiana's. On our second day, the waves were supposed to be around 1-2 feet, but they turned out to be upwards of 6 feet. Fortunately, we could still collect numerous samples at our Alabama sites.

Finally, before leaving for our Florida site, Paul and Rebecca informed us that the boat in Florida would not be functional for our offshore travels. Instead, we spent our day off going to the local beach and aquarium and participating in a beautiful riverboat cruise at Wakulla Springs State Park. In the end, I had a fun and eventful time during my fieldwork experience because of our collaborative efforts on the boat and fun adventures when we had days off!!

In addition to showing me more about the Deep South and connecting with Paul, Rebecca, and my peers, traveling to the Gulf of Mexico to do field research allowed me to understand the significance of fieldwork and its role in data collection. For example, I could examine the process of sieving the sediment and picking through live organisms and shells, which eventually led back to our work in the lab. The box core on the boat in Louisiana and Alabama brings up sediment samples, meaning there is no way to tell what is present before sieving and picking through it. This uncertainty allowed me to learn so much about the different types of bivalves and examine other organisms that we may or may not study.

Before joining the lab, I did not realize that there were so many pathways to take when conducting research about the tiny bivalves we were studying. These included analyzing microstructure, examining ecological and phylogenetic differences across sites, studying population genetics, and much more. I am interested to see what projects the Paleo Lab will take me and my peers on in the future.

Ideally, I want to pursue a career in Conservation Biology. As a double major in environmental studies and biology, my most significant interest is studying how humans affect the environment, specifically how humans affect organisms. The experience in the field only excited my interest in working in the field and with live organisms. Our fieldwork experience showed me the often hidden, yet still significant, steps of storing and shipping specimens. The process of labeling bags and cards, as well as counting the live specimens, often goes overlooked. My time in the field was highly beneficial for my career in the sciences. I know so much more about conducting research, examining data, and answering scientific questions now than ever.

Guest post by Emma Lewis ('25).

Leading up to our trip to the Gulf of Mexico, we talked a lot about preparing for long days, hot sun, tiring work, and seasickness, and I was nervous to be starting the summer off with what sounded like a less-than-relaxing experience. But when we left the dock in Louisiana the first morning, I was immediately excited just to be out at sea. It was a two hour ride out to the site, and I spent it on the boat deck looking out at the seemingly endless waves, feeling the pleasant (and sometimes hat-threatening) breeze in my face, and watching dolphins swimming in the wake of the boat. I was struck by the power of the ocean and found myself thinking about its vastness and contents. I also spent the ride doing what Paul recommends we do while the microscopes are loading; thinking about my future.

As a rising senior, my thesis and the graduate school application process are no longer problems for my distant future. I was feeling anxious about my decision to go to graduate school right after Colgate, and unsure that I had enough experience and information to make the big decision of choosing a graduate program and potentially devoting my future to research. But over the course of this field work, I became much more confident about what I want for my future, and I am very grateful for the experience.

I realized that I really loved doing fieldwork - watching the samples come up on the deck, getting covered in mud while sieving, and getting stoked with everyone when we found live clam samples or a cool organism that needed identification were joyful and purposeful experiences for me. I especially enjoyed how Paul and Rebecca, with their different backgrounds, had fascinating knowledge about the species we were finding, and they were learning from each other as well. It showed me how much opportunity there is in interdisciplinary science to spend a whole lifetime learning new things from different people, and I think that marine science is a great field to bring together all kinds of scientific disciplines in cool projects like the ones we are working on now.

After this experience, I am excited instead of nervous to be researching marine biology graduate school programs, and I can more clearly envision my future as a scientist. I have learned about marine invertebrates, how research works, graduate school expectations and opportunities, and formed lasting connections with my peers and professors.

Guest post by Olivia Miller ('27).

Being on the water was spectacular. Even though we were working hard, it felt like play. I loved making a muddy mess as we sifted through the sediment, and I couldn’t stop laughing as we surfed on seven-foot waves on the rough days. I cherish my memories of cat naps on the sunny bow of the boat, watching dolphins glide through the water at our sides, and getting splashed by rogue waves that lapped up at the open deck while we worked. Even when I felt horribly seasick (enough to warrant me racing to the side of the boat), I was so happy to be out exploring the Gulf. Our fieldwork was a gold mine for curious minds.

I didn’t expect to like the work as much as I did, but I found it exciting and fun. Sieving the sediment was strenuous, and picking through the shells was tedious, but there were discoveries to be made with every sample. In our free time, we visited aquariums, went on boat tours, and explored the beach. I thought that at some point, I must get sick of the ocean, but I never did.

If anything, I only grew to love it more. I confess that I found that fieldwork in Alabama to be more enjoyable than our time in Louisiana, but that’s probably just because I’d gotten used to some of the more “inspiring” aspects of working on the boat. Our last day on the water was my favorite. Because of rough conditions, we quickly learned that we couldn’t sample at our intended site, so we boated closer to the coast and pulled samples from 10 meters depth rather than our usual 20. I made friends with lots of adventurous snails and crabs that day—we even found a hermit crab hiding in one of the samples! That night, we were told that the boat in Florida needed a repair and wouldn’t be ready for our scheduled visit the next week. I was horribly sad to learn that we wouldn’t be able to sample in Florida after having such a great time in Alabama, but I am incredibly grateful for the opportunities that I was afforded in the week before. If anything, the news made me realize how fortunate we were to be able to get on the water at all, and those memories are even more valuable in hindsight.

Our fieldwork was also a great opportunity to get to know the students and professors that I’ll be working with for the rest of the summer—I am lucky to do research with such hard-working, curious, and sincere people. Their jokes and stories made the trip so much more enriching. I was also incredibly impressed by Paul and Rebecca’s unwavering dedication and enthusiasm. Even when we hit some bumps in the road, they kept our morale high.

The days on the boat were full and exhausting, and I wouldn’t change a thing (except maybe the absurd number of polychaete worms we had to throw over the deck). I had the opportunity to engage with the samples every step of the way as they traveled from the ocean floor all the way to the microscope in our lab at Colgate. My immersion in this research brought me a newfound appreciation for each tiny little shell that we found. It also makes me excited to learn more about the samples in the lab as I’m reminded of the work we did to retrieve them and the memories we made along the way.

How are fossil records used to understand current extinction risk and inform conservation decisions at local to global scales? In our review (available early online here), Seth Finnegan, Rowan Lockwood, Heike Lotze, Loren McClenachan, Sara  Kahanamoku, and I provide an overview of the ecological and environmental information available in the fossil record and the application of recent and deep time fossil records in species risk assessment and conservation.

Finnegan, S., P.G. Harnik, R. Lockwood, H.K. Lotze, L. McClenachan, and S.S. Kahanamoku. In press. Using the fossil record to understand extinction risk and inform marine conservation in a changing world. Annual Review of Marine Science 16. https://doi.org/10.1146/annurev-marine-021723-095235

How do environmental conditions influence predator and prey body size? Luke Calderaro ('22), Marina Rillo, and I addressed this question by studying the empty shells of marine bivalves, and the predatory traces (drillholes) left behind by drilling gastropods, at sites located on the continental shelf between Louisiana and Florida. Luke measured more than 3000 bivalve shells and associated traces of drilling predation, and we worked with Marina to compile environmental data for our 15 stations. Using mixed-effects models, we examined the associations between environmental conditions and predator and prey size, while accounting for the sizes of different bivalve genera. Overall, we found that bivalves tend to be larger in low oxygen settings where predation is greatly reduced, and that the sizes of predators and prey tend to increase with sea surface temperature. To learn more, you can read our open-access article in Paleobiology here:  link. 

Calderaro, L.A., P.G. Harnik, and M.C. Rillo. 2023. Environmental correlates of molluscan predator-prey body size in the northern Gulf of Mexico. Paleobiology.

Post by Alexa Russo (Colgate '25)

My time in the Gulf was extremely valuable; from getting to see all the specimens - both ones we study and ones we don’t - up close and personal, to getting to have conversations with crew members, other students, interns, and scientists. While we primarily study marine bivalves (clams) in the Paleo Lab, we can’t control what gets picked up by the box core on the seafloor when we are sampling, which leads to us seeing so many cool critters like crabs, worms, sea stars, and even eels. I was able to learn so much over the course of three weeks, and I really enjoyed hearing about everyone’s interests and specialties, and learning about all the different career paths there are, and all the different fields of study that exist within the marine sciences. I especially enjoyed talking with two scientific scuba divers who helped us collect samples; I had never really thought about how useful scuba diving can be for scientific studies, and we talked about the process of getting certified to dive for scientific purposes.

While I personally don’t see myself being a marine scientist in the future as I am more interested in terrestrial paleontology for my future career, the skills I learned from being in the field will be extremely useful in the future regardless of the path I choose to take. I learned new field techniques, ways to collaborate with other scientists, and how scientists may come up with new projects or questions they want to answer. Additionally, I learned a lot about the importance of organization and labeling, even when you’re covered in mud on the back of a boat. After all, if we don’t know exactly where a sample came from, the data we get from it won’t tell us much, especially when we are studying the impact of environmental conditions on marine life. Overall, my experiences in the field will stick with me and be a benefit to my future, and I hope to apply the field skills I learned in the near future.