Publications

Spring 2025 Departmental Achievements

Posted on January 23, 2026January 23, 2026 by Hannes Baumann

Awards:

Professor Senjie Lin

Prof. Lin received the Darbaker Prize from the Botanical Society of America, honoring his research to better understand the biology of two distinct groups of marine phytoplankton (diatoms and dinoflagellates) that play a major role in global nutrient cycling and phytoplankton community dynamics.

PhD candidate Hannah Collins

Hannah received the World Aquaculture Society Student Spotlight award recognizing the best abstracts submitted by student to the Aquaculture 2025 meeting.

PhD candidate Halle Berger

Halle Berger received the Best Student Poster Award at the 2025 winter science meeting of the Southern New England Chapter of the American Fisheries Society. The poster was about Halle's research on modeling the effects of ocean acidification and warming on Atlantic sea scallop growth to inform adaptive fisheries management.

Grants:

Professors Cara Manning, Leonel Romero, Samantha Siedlecki

Profs Manning, Romero, and Siedlecki have received a $499,570 grant from the Long Island Sound Study Research Grant Program to investigate the drivers of oxygen depletion (hypoxia), and the duration and severity of low-oxygen conditions in western Long Island Sound using a combination of observational and modeling approaches.

Improved Mechanistic Understanding of Hypoxia Drivers in Western Long Island Sound Enabled with Data from a Wire-Following Profiler and Coupled Biogeochemical-Hydrodynamic Modeling

Professor Senjie Lin

Algae are both natural and industrial sources of renewable energy. Collaborating in a Columbia University-led multi-million-dollar project, Prof. Senjie Lin will lead his UConn team and contribute expertise on microalgae to advance the development of algae-based electricity-generating technologies.

ECO-SPARK: Enzymatic Conversion of Organic Carbon into Sustainable Power through Aquatic Reactors and Kinetics, DARPA $1,500,000

Publications:

Prof. Rob Mason

Samples for measuring the concentrations of different forms of mercury in the Pacific Ocean waters were collected on a research expedition from Alaska to Tahiti and analyzed by our research group and those of our collaborators. Former student Yipeng He and Robert Mason participated in the cruise and were involved in the sample analysis.

Starr, L.D., He, Y., Mason, R.P., Hammerschmidt, C.R., Newell, S.E., Lamborg, C.H. 2025. Mercury distribution and speciation along the U.S. GEOTRACES GP15 Pacific Meridional Transect. JGR Oceans 130: Article # 130e2024JC021672.

He, Y., Inman, H., Kadko, D.C., Stephens, M.P, Hammond, D.E., Landing, W.M., Mason, R.P. 2025. Elevated methylmercury in Arctic rain and aerosol linked to air-sea exchange of dimethylmercury
https://doi.org/10.1126/sciadv.adr3805.

Samples were collected on a research expedition in the Bering and Chukchi Seas off Alaska in the atmosphere and in the ocean waters to examine the factors effecting the inputs of various mercury (Hg) compounds to the ocean from the atmosphere and the loss of gaseous forms of Hg to the atmosphere, with a focus on the exchange of methylated Hg forms.

Zhou, C., Liu, M., Mason, R.P., Assavapanuvat, P., Zhang, N.H., Bianchi, T.S., Zhang, Q., Li, X. Sun, R., Chen, J., Wang, Raymond, P.A. 2025. Warming-induced retreat of West Antarctic glaciers weakened carbon sequestration ability but increased mercury enrichment. Nature Communications 16: Article # 1831.

The publication examined how the recent changes in climate is affecting the inputs of mercury (Hg) to the ocean waters off of Antarctica and the relative importance of inputs from the continent versus inputs from the atmosphere, and how these inputs differ for Hg compared to carbon. The study used information from ancient sediments to infer what will likely happen in the future in a changing climate.

Prof. Samantha Siedlecki

Carlson, A. J., Siedlecki, S. A., Granger, J., Veitch, J., Pitcher, G. C., Fearon, G., et al. (2025). Seasonal source water changes and winds contribute to the development of hypoxia in St Helena Bay within the southern Benguela upwelling system. Journal of Geophysical Research: Oceans, 130, e2024JC021702. https://doi.org/10.1029/2024JC021702

This work discusses oxygen dynamics in St. Helena Bay (SHB), a productive area in the southern Benguela Upwelling System off western South Africa severely impacted by low oxygen events through fish mortality events. Specifically, it highlights the seasonal cycle of oxygen, including periods of hypoxia and anoxia, and the role of winds and source water changes in driving these variations.

Professor Hannes Baumann

Mosca, K.C., Savoy, T., R. Benway, J., Ingram, E.C., Schultz, E.T., and Baumann, H. (2025) Age structure and seasonal movement patterns of Atlantic sturgeon aggregating in eastern Long Island Sound and the Connecticut River. Fishery Bulletin 123:127-142

This study combined age analysis and telemetry to show that Atlantic sturgeon of all sizes frequently migrate into upper, freshwater portion of the Connecticut River

Jones, L.F., Schembri, S., Bouchard, C., and Baumann, H. (2025) Molecular identification of larval sand lance (Ammodytes spp.) caught in the Hudson Bay System 2010-2018. Environmental Biology of Fishes 108:305–316

PhD student Lucas Jones used genetics to find out what sand lance species inhabits the Hudson Bay in the Canadian Arctic.

Research Prof. Zofia Baumann

Hansen, G., Shumway, S. E., Mason, R. P., & Baumann, Z. (2025). Mercury distribution with size between the tissues of the northern quahog (= hard clam)(Mercenaria mercenaria). Environmental Pollution, 126287. https://doi.org/10.1016/j.envpol.2025.126287

This study examined the distribution of inorganic mercury (iHg) and methylmercury (MeHg) in the soft tissues of hard clams (quahogs) and found that muscular tissues contained a higher proportion of MeHg, while the viscera and mantle also harbored inorganic Hg.

Graduate student Eva Scrivner

Scrivner, E., Mladenov, N., Biggs, T., Grant, A., Piazza, E., Garcia, S., Lee, C.M., Ade, C., Tufillaro, N., Grötsch, P., Zurita, O., Holt, B., Sousa, D., 2025. Hyperspectral characterization of wastewater in the Tijuana River Estuary using laboratory, field, and EMIT satellite spectroscopy. Science of The Total Environment 981, 179598. https://doi.org/10.1016/j.scitotenv.2025.179598

The research links the chemical composition of effluent wastewater discharge in the Tijuana River Estuary with laboratory, field, and hyperspectral satellite spectroscopy. This work serves to inform real-time water quality monitoring in a heavily polluted coastal urban center.

At DMS phytoplankton are now on IFCB-TV

Posted on February 5, 2025February 6, 2025 by Hannes Baumann

The team of DMS researchers Dr. Zofia Baumann, Dr. Kate Randolph and Hazel Levine are happy to share that a major new instrument has begun its long anticipated work. The Imaging Flow Cytobot - or IFCB for short - is for now installed in the Rankin Seawater lab, after being purchased with a UConn-CLAS shared equipment grant nearly two years ago (Dierssen, Baumann et al.).

The instrument has the capacity to monitor and display in real time the breath-taking diversity of microscopic life in the ocean. Our IFCB focuses on the smaller size classes 5 - 150 um, which mostly represent single cell algae and small mixotrophs.

Leveraging additional NSF support, we were able to overcome challenges with operating the IFCB on a routine basis. The IFCB now accesses the intake line of the Rankin Lab (a very small fraction of it) and then photographs any particles and characteristic shapes. The compilation below shows a given size range to illustrate some of the diversity. The IFCB now records these images and displays them on a public-facing online Dashboard, which can be mesmerizing to watch.

Plankton-composite — The composition of some of the larger phytoplankton as captured by the IFCB on February 6th 2025.

The implementation of the IFCB in Rankin Lab was led by Kate Randolph and greatly supported by Hazel Levine, Bob Dziomba, Charlie Woods, Todd Fake, and Chris Mills! Thank you.

The next step is to develop an AI-based classification system for automatic species identification. This will still take time, but we are collaborating with other IFCB users, including its inventors, and are optimistic about the progress ahead.

We hope you enjoy the stunning images of phytoplankton on what we like to call

"IFCB TV" !

Summary of Summer/Fall 2024 Departmental Achievements

Posted on December 2, 2024March 8, 2025 by Hannes Baumann

Awards:

Professor Samantha Siedlecki

Prof. Siedlecki was named as a 2024 – 2025 Fullbright Scholar for research in both Italy and South Africa, which has been featured at UConn Today

Professor Hans Dam

Professor Dam had the honor of giving the Maxilliped Lecture on “Copepods as Model Systems for the Study of the Response of the Biota to Global Change” during the 15th International Conference on Copepoda held in Hiroshima, Japan.

Research Faculty Sandra Shumway

Dr. Shumway was awarded the Distinguished Lifetime Achievement Award by the US Aquaculture Society and is the first female to receive the award. She was also appointed Fellow of the Marine Biological Association, FMBA. MBA Fellows are senior practitioners in marine biology who have contributed to the discipline at the highest level. The title of Fellow of the Marine Biological Association, FMBA, was first awarded in 2014, following granting of a Royal Charter to the Marine Biological Association. There are currently 50 MBA Fellows.

Professor Senjie Lin

Professor Lin has been awarded the 2024 UConn-AAUP Excellence Award in as well as the 2024 Alumni Faculty Excellence Award in Research and Creativity.

Research Scientist Susan A. Smith (Mystic Aquarium):

Sue won first place in Animal Welfare Research for her presentation at the annual Association of Zoos and Aquariums conference in Calgary. Her work involved the use of non-invasive fecal samples to elucidate the microbiome and hormone profile of the African Penguin, along with the development of a genetic sexing test, which will soon be used to aid in the monitoring of endangered wild populations in South Africa.

PhD student Paxton Tomko

Paxton was awarded a National Science Foundation Graduate Research Fellowship (NSF-GRFP) for research with Professor Pieter Visscher, which was featured at UConn Today

PhD Candidate Halle Berger

Halle was awarded the 2024 National Marine Fisheries-Sea Grant Fellowship by NOAA making her the first UConn student to ever receive the award.

Grants:

Professor Senjie Lin

Prof Lin will collaborate with the University of Columbia and Yale University on a DARPA-funded multi-year (2024-2027) project that aims to utilize algal genomics to develop biosensors for various environmental stimuli

MEBES: Modular engineered biosensors for environmental sensing

Research Professor Paola Batta-Lona, Professor Hannes Baumann

Led by UConn EEB professor Eric Schultz, co-PIs Batta-Lona and Baumann will collect and analyze novel data on short- and long-term changes in the trophic ecology of species of greatest conservation need.

Bottoming Out? Testing Hypotheses on Why Long Island Sound Flatfishes Are Disappearing (Long Island Sound Study, $316,667).

Professor Heidi Dierssen and Research Professor Paola Batta-Lona

In collaboration with colleagues from URI, Dierssen and Batta-Lona will use eDNA to characterize biological communities in shallow seafloor, deep-sea seafloor, and offshore midwater acoustic soundscapes. Additionally remote sensing data and Distributed Sensing enabled Cabled Observatories (DiSCO’s) will be used for broader scale understanding of major ocean processes in these areas.

Coastal and Offshore Biogeochemical Oceanographic Observatories Enabled with Distributed Sensing (NIUVT, $2,126,000)

Research Scientist Zhuomin Chen

Projecting future changes in the Gulf Stream warm-core rings and their impacts on the Northeast U.S. Large Marine Ecosystem in a changing climate using regional MOM6 simulations (NOAA $570,000)

Research Scientist Tracy Romano (Mystic Aquarium) and Associate Professor in Residence Michael Finiguerra:

Drs Romano and Finiguerra were awarded an NSF grant to continue leading the Research Experience for Undergraduates (REU) program through an ongoing collaboration with Mystic Aquarium and the University of Connecticut Avery Point campus.

Romano, T.A., Finiguerra, M. REU Site Mystic Aquarium: Collaborative Research: Plankton to Whales: Consequences of Global Change within Marine Ecosystems. National Science Foundation. $464,997.

Research Scientists Ebru Unal and Tracy Romano (Mystic Aquarium):
Drs Unal and Romano were awarded a North Pacific Research Board grant to further study the transcriptome of the beluga whale for the monitoring of wild populations, in an effort to isolate the health-related expression discrepancies between healthy and endangered populations.

Romano, T.A., Unal, E. The Beluga Skin Transcriptome as a Novel Tool for Monitoring Alaska’s Beluga Stocks. North Pacific Research Board. $244,601

Dr. Romano also received funding by the North Pacific Research Board to design and run a cultural exchange that allowed young Native Alaskans to visit Connecticut, where they met with local CT Native American youth, and together took part in educational and cultural workshops.

Romano, T.A., A Science Based Educational and Cultural Exchange Workshop at Mystic Aquarium for Alaska Native and Native American Youth. $20,000

Publications:

Prof. Hans Dam

Prof. Dam co-authored a study about the negative effects of marine heatwaves on copepods. The authors found that acclimation (“getting used to”) and parental effects (“the fate of the children depends on the experience of the parents”) mitigate the negative effects of heat waves on the fitness of two important copepod species.

Sasaki, M.C, M. Finiguerra, H.G. Dam. 2024. Seasonally variable thermal performance curves prevent adverse effects of heatwaves. Journal of Animal Ecology 2024;00:1–11. DOI: 10.1111/1365-2656.14221

Graduate student Samantha Rush and Professor Penny Vlahos

This study reports on how sea ice in the Arctic Ocean incorporates and stores boron as it forms, reducing the amount of boron from under ice waters.

Rush, S., Vlahos, P., Lee, C.-H., Lee, K., Barrett, L. J. Boron to salinity ratios in the Fram Strait entering the Central Arctic: The role of sea ice formation and future predictions. Marine Chemistry. 267:104463. https://doi.org/10.1016/j.marchem.2024.104463

DMS alumnus Max Zavell and Professor Hannes Baumann

Zavell and Baumann show that the embryos and larvae of an abundant grouper species in Long Island Sound are unaffected by even very high CO2 levels in the water.

Zavell, M.D. and Baumann, H. (2024) Resiliency of Black Sea Bass, Centropristis striata, early life stages to future high CO2 conditions. Environmental Biology of Fishes 107:677–691

Research Prof. Paola Batta-Lona and Prof. Ann Bucklin

This morphological and molecular analysis revealed the diet differences of 7 mesopelagic fish species, showing the importance of gelatinous prey.

Bucklin, A., Batta-Lona, P.G., Questel, J., McMonagle, H., Wojcicki, M., Llopiz, J.K., Glancy, S., Caiger, P.E., Francolini, R., Govindarajan, A., Thorrold, S.R., Jech, M., Wiebe, P.H. (2024). Metabarcoding and morphological analysis of diets of mesopelagic fishes in the NW Atlantic Slope water. Front Mar Sci. 11:1411996. https://doi.org/10.3389/fmars.2024.1411996

Batta-Lona also published a study on the diet diversity of three salp species, which showed a wide variety of prey, broadening our understanding of trophic pathways in the mesopelagic food web.

Batta-Lona, P.G., Gardner, K., Questel, J.M., Thorrold, S.R., Llopiz, J.L., Wiebe, P.H., Bucklin, A. (2024). Salps in the NW Atlantic Slope Water: metabarcoding and compound-specific stable isotope analysis of diet diversity and trophic interactions. Mar Biol 171, 233. https://doi.org/10.1007/s00227-024-04535-x

Batta-Lona further published a study that identified parrot fish larvae via morphology and DNA sequences.

Morales‐Pulido, J. M., Galindo‐Sánchez, C. E., Jiménez‐Rosenberg, S. P. A., Batta‐Lona, P. G., Herzka, S. Z., Arteaga, M. C. (2024). A molecular approach to identify parrotfish (Sparisoma) species during early ontogeny. Journal of Fish Biology 1-10 https://doi.org/10.1111/jfb.15921

Batta-Lona was also involved in the MetaZooGene Atlas and Database (MZGdb) provides DNA sequences for multiple genes, with unique capacity for searches by ocean region.

O'Brien, T., Blanco-Bercial, L., Questel, J.M., Batta-Lona, P.G., Bucklin, A. (2024). MetaZooGene Atlas and Database: Reference Sequences for Marine Ecosystems. Methods in molecular biology 2744: 475-489. https://doi.org/10.1007/978-1-0716-3581-0_28

Prof. Peter Auster

Prof. Auster used diver surveys of reef fish off Florida to map predation risk to coral eating fishes.

Auster, P.J. and M.E. Cullerton. 2024. Can variation in fish predator density and the Landscape of Fear facilitate coral restoration success? Reef Encounter 39:48-50.

In another study, Prof. Auster and colleagues argue that the term "destructive fishing" is used in international agreements and guidance without agreement on what this term means.

McCarthy, A.H., D. Steadman, H. Richardson, J. Murphy, S. Benbow, J.I. Brian, H. Brooks, G. Costa-Domingo, C. Hazin, C. McOwen, J. Walker, D. Willer, M. Abdi, P.J. Auster, ..., N. Mukherjee. 2024. Destructive fishing: An expert‐driven definition and exploration of this quasi‐concept. Conservation Letters, e13015. https://doi.org/10.1111/conl.13015

Post-doctoral researcher Danielle Freeman

Dr. Freeman published an article together with colleagues at WHOI that forecasts the effects of sunlight-driven chemistry during oil spills.

Freeman, D. H.; Nelson, R. K.; Pate, K.; Reddy, C. M.; Ward, C. P. (2024) Forecasting Photo-Dissolution for Future Oil Spills at Sea: Effects of Oil Properties and Composition. Environ Sci Technol. 58: 15236-15245 https://doi.org/10.1021/acs.est.4c05169

Research Scientist Ebru Unal (Mystic Aquarium):
Dr. Unal showed that skin samples can reveal relevant differences between endangered and stable beluga whale populations.

Unal, E., V. Singh, R. Suydam, C.E. Goertz, and T.A. Romano. (2024). Comparative skin transcriptome analysis as a potential tool to investigate intra- and inter-population differences in belugas. Frontiers in Marine Science: Marine Conservation and Sustainability. 11:1282210

Research Scientist Tracy A. Romano (Mystic Aquarium):

Aerial photogrammetry and lipid analyses can be used to describe the body condition of wild endangered St. Lawrence Estuary beluga whales.

Sherill, M., A. Bernier-Graveline, J. Ewald, Z. Pang, M. Moisan, M. Marzeliere, M. Muzzy, T.A. Romano, R. Michaud, and J. Verreault. (2024). Scaled mass index derived from aerial photogrammetry associated with predicted metabolic pathway disruptions in free ranging St. Lawrence Estuary belugas Frontiers in Marine Science. 11:1360374.

Danielle A. Lavoie (Mystic Aquarium):

This study provided insight into the detection of the invasive nematode parasite A. crassus using identification monitorting methods that allow for the survival of the host A. rostrata (the American eel).

Lavoie, D.L., Oliveira, K. (2024). Non-Lethal Detection of the Invasive American Eel Parasite Anguillicoloides crassus. Diseases of Aquatic Organisms.

A delayed spring bloom along the West Antarctica Peninsula

Posted on December 2, 2024December 2, 2024 by Hannes Baumann

By Samantha Rush.

If you think about the holiday season, it is easy to grasp the trend that Christmas festivities that used to begin traditionally after Thanksgiving in the US appear much earlier. In recent years, the timeline has shifted and many Christmas and holiday themed advertisements, decorations, and events appear even sooner than before. Of course, this notable shift has traceable causes and is known (consciously or subconsciously) to be driven by retail strategies, commercialization, consumer behavior, social media influences, and cultural shifts.

The changes in the timelines of global phenomena also extend to marine environments. In fact, the polar regions are some of the most rapidly changing locations on the planet due to human induced climate change. In the West Antarctic Peninsula (Figure 1), a combination of warming and sea ice loss have altered the timing of recurring seasonal events, the study of which is known as phenology. While most predictions have suggested that these changes in the environment would cause an earlier spring bloom, or ocean biology to kick start, lead author and postdoctoral researcher Jessie Turner found exactly the opposite in a recent study of the ice-associated waters west of the Antarctic Peninsula.

Using satellite ocean color data from 1997 to 2022, researchers from the University of Connecticut and five other collaborating institutions and laboratories discovered that spring blooms were shifting later in ice zones and on continental shelf regions west of the Antarctic Peninsula (Figure 2). By using satellite derived chlorophyll-a concentrations as a proxy for phytoplankton biomass, researchers were able to track the concentration and timing of the elevated concentration corresponding to the date when heightened biological activity begins.

After investigating a handful of environmental variables to better ascertain the potential mechanisms for the seasonal shift, the authors found that wind speed was the most likely mechanism for the observed change in the spring bloom start date. Other variables such as light and temperature did not explain the trends. However, there was a long-term increase in wind mixing, which likely decreases the stability of the water column in the early spring season and suppresses phytoplankton accumulation until later in the season (Figure 3).

While phytoplankton are small single cell plants, the timing of the phytoplankton spring bloom affects the entire marine food web. Higher trophic level organisms may experience feeding, migration, and breeding impacts. In fact, phenology changes at the base of the Antarctic food web are likely to disrupt the life history of key species such as Adélie penguins. Other, widespread impacts also include potential changes to the timing and magnitude of carbon dioxide absorption by the ocean in these locations.

Next, the researchers plan to investigate specific phytoplankton species and employ the use of new generation hyperspectral satellite missions to further study long-term trends in polar regions. Rapidly developing technology combined with field measurements will allow for better examinations of the changes rapidly occurring in this polar region in studies to come.

Jessica S. Turner, J.S., Dierssen, H., Kim, H.H., Stammerjohn, S., Munro, D.R., and Kavanaugh, M. (2024). Changing phytoplankton phenology in the marginal ice zone west of the Antarctic peninsula. Marine Ecology Progress Series 734: 1–21

Heat tolerance changes across environments and populations

Posted on March 27, 2023March 27, 2023 by Hannes Baumann

March 27th 2023 - By Ewaldo Leitao.

Climate change is a threat to species persistence. Increasing temperatures affect species differently depending on their habitats, such as land or the ocean. However, species often consist of different populations (groups of individuals that reproduce together) that experience different temperature conditions. And if populations live in these areas long enough, they can genetically adapt to their local conditions. What does that mean? If the same species has a population in an area where it is constantly warm, like the tropics, and another population that lives in colder regions, like Connecticut, then we’d expect the tropical population to handle high temperatures better compared to the population living in colder regions. This kind of diversity within species affects how we think about the vulnerability of the species as a whole. To add another layer, if variation differs for terrestrial vs. oceanic species, we might be missing important information about where climate change will have the strongest effects on the planet.

That is what Dr. Matt Sasaki and collaborators investigated in a paper recently published in Nature Climate Change. Their main goal was to assess the heat tolerance (the highest survivable temperature) of populations in many different species, from different realms – terrestrial, freshwater, marine and intertidal. They assessed the vulnerability of species by surveying in the literature from the whole world that measured individual heat tolerance. They compiled and then conducted a meta-analysis of these published data, thereby assessing how the heat tolerance is related to the thermal environment these populations live in.

“This paper came out of the ‘Evolution in Changing Seas’ Research Coordination Network (RCN). Back in 2019 they brought some of us together at Shoal’s Marine Lab for a synthesis workshop and essentially told us to think about questions at the intersection of evolutionary biology and marine science”, said Matthew Sasaki, about the seed of the idea.

"I really enjoyed the collaborative aspect of this project, even though I’ve met most of the co-authors in person only once (or not at all!)"

By measuring how heat tolerance changes between populations of the same species, they found that marine and intertidal species show a decrease of heat tolerance between populations as the environment gets colder, but that was not observed in terrestrial and freshwater populations. This was an interesting result, because since the ocean is largely connected, they expected that there would be a smaller differentiation in the ocean compared to land, where geographical barriers can create physical separations, allowing difference in heat tolerance to build up among populations within a species.

Behavior may play a role in the observed patterns. In the terrestrial realm, many organisms can moderate body temperature by seeking shade and forested areas to find refuges from the heat. Even plants can exploit micro-climates. This decreases the amount of evolutionary pressure on terrestrial organisms, when compared to other realms.

This study highlights the importance of accounting for evolutionary processes in the context of climate change and species persistence and extinction risk. Larger differentiation of heat tolerance within species may suggest a potential for evolutionary rescue. That is, populations with genes that allow them to be “warm adapted” may rescue populations that are more susceptible to increasing warming.

We asked what was the coolest part about the execution and findings of the project. “This wasn’t a project someone could do alone, and it was really cool to be part of such a big collaborative effort. The findings themselves were also really exciting for us. We expected there to be pretty clear differences between marine and terrestrial taxa, but we were surprised to see that local adaptation seems to be stronger in marine species and not terrestrial species. This goes against some of the traditional paradigms (that marine species’ are more often homogenized by larval dispersal, for example), and hints at a cool role of behavioral thermoregulation in shaping patterns in evolutionary adaptation.”

“This was definitely a pandemic pet project. I won’t say the pandemic helped us make progress though. This ended up being something we worked on a little bit each week for a couple years. Maybe that helped us put together a more robust product (slow and steady wins the race?). I really enjoyed the collaborative aspect of this project, even though I’ve met most of the co-authors in person only once (or not at all!). Having to do everything virtually definitely changed the nature of the collaboration (more written exchanges, less whiteboard brainstorming) but I think we made it work. We’ve just started working together on a couple new projects that build from this initial work, so it must not have been too terrible.”, said Matt.

Sasaki M, Barley JM, Gignoux-Wolfsohn S, Hays CG, Kelly MW, Putnam AB, Sheth SN, Villeneuve AR, Cheng BS (2022) Greater evolutionary divergence of thermal limits within marine than terrestrial species. Nature Climate Change. 2022 Dec 1:1-6.

DMS Kayla Mladinich shows that bivalves can reject microplastics

Posted on November 8, 2022November 8, 2022 by Hannes Baumann

8 November 2022. DMS is happy to share the latest publication by PhD student Kayla Mladinich, showing the surprising but good news that blue mussels and oysters appear not to ingest all microplastic particles floating in the water.

By Kayla Mladinich.

Oysters and mussels are filter feeders that draw particles in from the surrounding water to be eaten. These animals can select which particles are eaten or rejected depending on factors such as particle size and surface properties. This study was performed to determine what kinds of microplastics will be consumed or rejected by oysters and mussels. Both species rejected larger microplastics more than smaller microplastics and did not differentiate between different types of plastic polymers. The results suggest that oysters and mussels will not ingest all microplastics that they are exposed to in the natural environment!

The Arctic is not so Boron!

Posted on September 21, 2022October 7, 2024 by Hannes Baumann

Professor Penny Vlahos investigates what happens with the ocean chemistry at the marginal ice zones in her recent publication

By Ewaldo Leitao.

The Arctic Ocean is undergoing rapid changes due to climate change. Increasing temperatures result in decreasing sea-ice extent, constant decreasing and thinning of permanent sea-ice caps. Some projections even show a completely ice-free Summer by 2050!

Another consequence of climate change is ocean acidification due to increasing atmospheric CO2. That leads to the decrease in water pH and changes in carbon chemistry dynamics. The Arctic may be a small ocean (3% of total oceans area) but it has an important contribution to carbon uptake (10%). Therefore, it is necessary to understand the impact of these changes across the oceans, including the Arctic, in order to be prepared for it.

Some chemical elements, such as boron, contribute to the ocean’s capacity to resist changes in pH, that is ocean’s alkalinity. Boron, in combination with salinity, has been used as a universal rule in the open ocean (boron to salinity ratio) in order to understand the contribution of boron to alkalinity, and therefore ocean carbon chemistry. But how does that change in the less saline areas, such as the marginal ice zones of the Arctic?

In the recent paper published in Nature Communications, Prof. Penny Vlahos and graduate student Lauren Barrett observed that, when measured in low salinity areas (marginal ice zones), the boron to salinity ratio deviates from the expected in open oceans. In a cruise that took place in May of 2021 (you can read more about the cruise here), researchers were surprised to find significant deviations in the boron to salinity ratios in ice and brine samples. Lower water temperature and lower salinity alters the exchange between boric acid and borate, which is used to determine the contribution of boron to sea water alkalinity (capacity of water to resist changes in pH and acidification), driving this deviation of the boron to salinity ratio compared to open ocean waters.

The unique microenvironment of the marginal ice zones creates a very dynamic system. As seawater freezes, salts are rejected, but there is still a liquid region between ice crystals, called brine channels. These channels allow boron to undergo inorganic changes that may result in the variations observed in some of the samples, increasing the variability of boron to salinity ratio observed in these Arctic areas.

Prior to boarding the research vessel, researchers had to quarantine for two weeks. But this was a valuable time to Lauren Barrett. “Over quarantine I spent a lot of time reading about the various uncertainties that other authors encountered in accurately and precisely constraining the carbonate system in this highly heterogeneous environment. The boron to salinity ratios that we present here warn against applying universal ratios constrained in the open ocean to marginal ice zones and ice environments.” says Lauren.

Lauren also shared a little bit about her experience: “I am very grateful for the opportunity to work with our international coauthors. The collaborative and interdisciplinary nature of marine science is one of my favorite aspects of working in this field. This research cruise was a great experience both personally and professionally, and I continue to be grateful to work in a field where cruising and getting to see polar bears is all in a day's work.”

The Arctic is an important sink of carbon and yet highly susceptible to climate change. Therefore, understanding detailed information of this system, instead of applying universal ratios, is necessary in order to better understand the carbon chemistry of the Arctic and be prepared for the consequences of climate change.

Posted on April 7, 2022April 7, 2022 by Hannes Baumann

A potential ripple effect from carbon in the atmosphere could have severe impacts throughout the ocean ecosystem

MEPS-sandlance — *This photo shows sand lance embryos that have and have not hatched. Sand lance have trouble hatching at future ocean CO₂ levels (photo courtesy of Emma Cross)*.

By Elaina Hancock. Reposted from UConn Today, 7 April 2022

When carbon is emitted into the atmosphere, about a quarter of it is absorbed by the earth’s oceans. As the oceans serve as a massive ‘sink’ for carbon, there are changes to the water’s pH – a measure of how acidic or basic water is. As oceans absorb carbon, their water becomes more acidic, a process called ocean acidification (OA). For years, researchers have worked to understand what effect this could have on marine life.

While most research so far shows that fish are fairly resilient to OA, new research from UConn, the University of Washington, the National Oceanic and Atmospheric Administration (NOAA), and Southern Connecticut State University, shows that an important forage fish for the Northwest Atlantic called sand lance is very sensitive to OA, and that this could have considerable ecosystem impacts by 2100. The team’s findings have just been published in Marine Ecology Progress Series 687.

Sand lance spawn in the winter months in offshore environments that tend to have stable, low levels of CO₂, explains UConn Department of Marine Sciences researcher and lead author Hannes Baumann.

“Marine organisms are not living in a uniform ocean,” Baumann says. “In near shore environments, large CO₂ fluctuations between day and night and between seasons are the norm, and the fish and other organisms are adapted to this variability. When we stumbled upon sand lances we suspected they are different. We thought that a fish that lives in a more open-ocean offshore environment might be more sensitive than the near-shore fish because there’s just much less variability.”

The project was a collaboration with physical oceanographers, including Assistant Professor of Marine Sciences Samantha Siedlecki and Michael Alexander from NOAA’s Physical Sciences Laboratory in Boulder, Colorado, who modeled CO₂ levels in 2050 and 2100 for a specific part of the Gulf of Maine where sand lance spawn. Then Baumann and his team reared sand lance embryos in the lab under experimentally higher CO₂ levels matching the projected levels.

There are instances of direct fish mortality as result of elevated CO₂, but they are rare, says Baumann. However, sand lance embryos proved to be exceptionally sensitive, and fewer embryos hatched under future oceanic CO₂ conditions. The researchers repeated the experiments three more times to avoid jumping to conclusions but each time they observed the same result.

“We found that embryo survival-to-hatch decreased sharply with increasing CO₂ levels in the water, concluding that this is one of the most CO₂-sensitive fish species studied thus far,” Baumann says.

Sand lances are surely one of the most important forage fish here on the Northwest Atlantic shelf… The humpback whales, sharks, tuna, cod, shearwaters, terns — you name it — they are all relying on sand lance.

With this interdisciplinary approach combining model forecasts and serial experimentation the researchers arrived at a picture that is much more specific.

“We consequently applied principles of serial experimentation, which is a most timely and important topic in ocean acidification research right now,” Baumann says. “Because our findings are backed up by repeated independent evidence, they are more robust than many published ocean acidification studies to date.”

In addition to preventing many sand lance embryos from developing normally, the researchers document a second negative, and novel, response to elevated CO₂. Higher CO₂ levels appear to make it harder for embryos to hatch.

Baumann explains the lowered pH likely renders enzymes needed for successful hatching less effective, leaving the embryos unable to break through their eggshell (chorion) to hatch.

The results show that by 2100, due to acidification, sand lance hatching success could be reduced to 71% of today’s levels. Since sand lance are such a critical component of the food web of the Northwest Atlantic, this marked decrease in sand lance would have profound impacts throughout the ecosystem.

“Sand lances are surely one of the most important forage fish here on the Northwest Atlantic shelf,” Baumann says. “Their range spans from the Mid Atlantic Bight all the way to Greenland. Where we studied them, on Stellwagen Bank, they are called the backbone of the ecosystem. The humpback whales, sharks, tuna, cod, shearwaters, terns — you name it — they are all relying on sand lance, and if sand lance productivity goes down, we will see ripple effects to all these higher trophic animals. Even though we humans don’t fish for sand lance, we need to take care of the species because it has such a huge effect on everything else.”

Baumann says this study supports the hypothesis that offshore, high latitude marine organisms like the sand lance may be among the most vulnerable to OA. As a result, these organisms and food webs will likely be impacted first and soon, and we must act now.

Previous research has focused on opportunistically chosen species when testing their sensitivity for ocean acidification, says Baumann, but this should change.

“We need strategic thinking about what species we are testing next, because we cannot test every marine fish species, that’s an impossible task. We should concentrate on fish species that are likely the most vulnerable, and therefore the ones that are probably being affected first and this research makes a compelling argument that those are the fish species at higher latitudes and in more offshore than nearshore environments.”

Baumann, H., Jones, L.F.*, Murray, C.S., Siedlecki, S.A., Alexander, M., and Cross, E.L. (2022)
Impaired hatching exacerbates the high CO₂ sensitivity of embryonic sand lance, Ammodytes dubius
Marine Ecology Progress Series 687:147-162

DMS researchers contribute to study on copepod climate adaptation

Posted on March 3, 2022 by Hannes Baumann

One of the most difficult challenges facing scientists is predicting how organisms will respond to rapid global change. A collaboration between oceanographers at the University of Connecticut and evolutionary biologists at the University of Vermont is looking into how copepods (tiny crustaceans that rival insects as the most abundant animals on the planet) adapt to ocean warming and acidification. This requires understanding the underlying genomic mechanisms that allow these animals to adapt, and the constraints to adaptation. This study by Reid Brennan and collaborators is a lucid example of this approach, identifying sets of genes that are linked to copepod adaptation to stressful new environments, and showing that the ability of these animals to respond to changing conditions is challenged after prolonged adaptation. Therefore, there are limits to adaptation that can constrain the resilience of animal populations to environmental stress.

Brennan, R.S., deMayo, J.A., Dam, H.G., Finiguerra, M., Baumann, H., and Pespeni, M.H. (2022)
Loss and recovery of transcriptional plasticity after long-term adaptation to global change conditions in a marine copepod
Nature Communications 13:1147

DMS faculty contributes textbook chapter on Fish Ecology

Posted on March 3, 2022March 3, 2022 by Hannes Baumann

3rd March 2022. DMS faculty Hannes Baumann contributed a chapter to the new textbook Marine Biology: a functional approach to the oceans & their organisms (Taylor & Francis), which has just been published. The chapter is based on Baumann's long-running class "Ecology of Fishes" (MARN4018/5018), touching on a large variety topics including fish evolution, zoogeography, metabolism, growth, reproduction & basic concepts of fisheries science. The book is geared towards advanced undergraduate and graduate students, stimulating interest while encouraging readers to seek out further in-depth sources.

Baumann, H. (2022) Chapter 11: Fish Ecology
In: Pan, J. and Pratolongo, P.D. (eds) Marine Biology: a functional approach to the oceans and their organisms. CRC Press/Science Publishers (Taylor & Francis)
ISBN 978-0-367-02498-7 (hardback), 978-0-429-39924-4 (e-book) | published March 3rd 2022

"With about 28,000 known species, fishes make up more than half of all known vertebrates (Helfman et al. 2009). Over the course of their long evolutionary history they radiated in every conceivable aquatic habitat, from the open ocean and deep-sea trenches to shelf seas, estuaries and lakes, to rivers and the smallest streams and ponds. They are found in subzero Antarctic waters, altitudes of over 4,000 m and even acidic desert springs of > 40°C (Moyle and Cech 2004). The fascinating adaptations to these habitats have produced a mind-bending diversity of form and function, a difference in size that spans more than three magnitudes (0.01 – 18 m), and a profusion of reproductive strategies. Apart from their diversity and unique evolutionary history, fishes are of intense scientific interest for economic reasons, because they comprise the nutritional foundation for a large part of humanity (Costanza et al. 1997) and their exploitation over time has led to thriving – and warring – civilizations. Today, the impetus of sustainable fish management at a time of rapid ecological re-organization due to man-made climate change has made the study of fish ecology and fish stock productivity as urgent and important as ever."

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Under Ocean Acidification, Embryos of a Key Forage Fish Struggle to Hatch

A potential ripple effect from carbon in the atmosphere could have severe impacts throughout the ocean ecosystem