Author: Schuler, Debra

Marine Sciences researchers publish long-term zooplankton adaptation experiment

Reposted from UConn Today –
By Elaina Hancock – UConn Communications | August 26, 2021

The world’s oceans are becoming increasingly stressful places for marine life, and experts are working to understand what this means for the future. From rising temperatures; to acidification as more carbon enters the waters; to changes in the currents; the challenges are multifaceted, making experiments and projections difficult.

Copepods are small marine animals that are abundant, widely dispersed, and serve as major structural components of the ocean’s food web. A team of scientists from the University of Connecticut, Jinan University in China, and the University of Vermont have found that a species of copepod called Acartia tonsa can cope with climate change, but at a price. Their research was published in Nature Climate Change (

“We have this problem of climate change and in the ocean, it is a multi-dimensional problem because it’s not just the warming, the ocean is becoming more acidic where pH is going down as we pump more CO2, into the atmosphere. Organisms need to cope, they are under more stress, and things are happening very fast,” says Hans Dam, UConn professor of marine sciences.

Dam explains that previous studies suggest some animals will be more sensitive than others to changes like shifts in pH. Prior studies with copepods showed they are not particularly sensitive to pH changes, but Dam points out those studies were only done with a single generation, or few generations, to a single stressor and shows the ability to acclimate rather than adapt. This new study not only looks at adaptation across 25 generations, it also considered both ocean warming and acidification (OWA), something that few studies have done until now.

“If you want to study the long-term effects, you must consider the fact that animals will adapt to changes or stress in the environment, but to do that you have to do the right experiments. Most people do not do those experiments with animals because it takes a long time to study in multiple generations.”

The researchers looked at fitness, or the ability of a population to reproduce itself in one generation, and how fitness would change through generations in increased OWA conditions. The first generation exposed to new OWA conditions suffered extreme reductions of over 50% of population, says Dam. It was as if OWA was a big hammer that greatly reduced the population fitness. By the third generation, the population seemed to have mostly recovered. However, by the 12th generation, the researchers began to see declines once again.

Though the copepods were able to adapt, the adaptation was limited because fitness was never fully recovered, and the researchers suspect there are some antagonistic interactions at play, leading to a tug of war situation between adaptation to warming and to acidification. These antagonistic interactions complicate predicting what responses can be expected.

James deMayo, co-author and UConn Ph.D. student adds, “Perhaps what’s important to emphasize with this project is that the effects of warming combined with acidification are not the same for every generation or organism that is adapting to that environment. That’s suggested by the data and why the adaptation is limited. While within intermediate generations, organisms might be very well adapted, in later generations, the effects of warming and acidification start to behave differently on the population. That’s one of the exciting parts about the research. It’s not a static, expected result for how organisms or their populations are going to continue to grow or decay.”

For example, deMayo explains, if you took individuals in later generations that had adapted to the experimental OWA conditions and placed them into the conditions of today’s ocean, they would not fare as well.

“That’s one negative consequence, that ability to not tolerate environmental shifts is a cost and an unpredicted consequence for evolutionary adaptation in a lot of systems, not just in copepods,” says deMayo.

The researchers point out that studies looking at single stressors run the risk of making overly simplified inferences about an organism’s ability to adapt, an especially risky proposition when making conclusions about such an integral component of the food web as copepods.

“Particularly when you involve living organisms, there are complexities that you can’t predict,” says Dam. “A priori, you might make the predictions, but you have no certainty that they’re going to unfold that way. In biology these are referred to as ‘emergent properties’ or things that you cannot predict from what you know in advance and this research is a good example.”

In thinking back to the hammer comparison, Dam says impacts in the copepod population have ripple effects through the whole food web and beyond.

“If fitness decreases by say, 10%, down the road we will have a 10% decrease in population size and since these animals are the main food source for fish, a 10% decrease in the world fishery is pretty significant,” says Dam. “And this is really the best-case scenario since in the lab, they’re essentially living in hotel-like conditions so that 10% isn’t taking into consideration other factors like predation or disease. In the real world we could see fitness recovery is actually much worse.”

Additionally, Dam points out another implication is that copepods sequester CO2 and reductions in their numbers reduce the ocean’s carbon sequestration capabilities, bad news at a time when more carbon sequestration is needed.

While the research offers promise for rapid adaptation, it is a reminder that as with many things in nature there’s a catch.

“There is some welcoming news, that yes, there is a recovery of fitness but there is also sobering news that the evolutionary rescue is not complete. There’s no such thing as a free lunch,” says Dam.


Professor Senjie Lin on AAAS Member Spotlight

Professor Senjie Lin is profiled on the Member Spotlight of the American Society for the Advancement of Science (AAAS). His research on dinoflagellate biology and its relevance to addressing harmful algal blooms, coral bleaching, and other climate change challenges is highlighted. The Spotlight, which can be found in, also reveals how Lin was drawn to science in general and to dinoflagellate work in particular.

When Life Gives You Lemons … Hold a Virtual International Fish Conference

By Elaina Hancock.
UConn Marine Sciences researcher Hannes Baumann left the 2019 Larval Fish Conference, the 43rd installment of the annual conference, with excitement for the 2020 American Fisheries Society Larval Fish Conference which was to be hosted by UConn. The planning and overall experience has been entirely different than he expected and turned out to be a real “lemons to lemonade” situation, says Baumann.

“For over 40 years, this small but important gathering has happily meandered between North American and European locations. The last in-person conference was 2019 in Palma de Mallorca. A treat. For 2020, I agreed that it now was my turn to organize a Larval Fish Conference. We were so excited, but you know what happened next,” says Baumann.

The 2020 conference had to be canceled outright, and plans started for 2021 in hopes it could be held in-person, but those too were later changed.

“We canceled the June 2020 in-person conference, but naively only postponed it by one year to June 2021, thinking then that one year later, we surely would be done with this virus and all the travel restrictions. So much for that. Again, in March of this year, we had to cancel the 2021 in-person meeting, but replaced it with a three-day virtual meeting that myself and a team organized in the months leading up to the conference.”

The ability to shift gears and ensure forward momentum is a valuable skill the workforce quickly acquired as a result of the pandemic. Baumann says the amount of help and hard work provided by University Events and Conference Services staff to make the switch to virtual has been essential.

“The staff has done a fantastic job with this. You can’t imagine how many things can go wrong, but the staff have solved all of these problems. We all have such gratitude for all their help.”

In pulling everything together, Baumann says the process was both exhausting and rewarding as turnout exceeded expectations.

“The virtual nature of the meeting led to a record diversity of registrants. The conferences were always international, but that meant largely European and North American countries, plus Japan, Australia and New Zealand. This year, we had talks and posters from 28 different countries, a record.”

Technology made it possible: the WebEx platform in particular, coupled with another platform called Gatherly to encourage networking, a difficult-to-replicate experience for virtual meetings.

“Here I was sitting in my New England office on Gatherly and a video chat would pop up with a colleague in British Columbia, when all of a sudden a little avatar joined in and popped up a conversation from New Zealand. Another person from Europe joined after that, and we were talking like we are talking right now. That was so cool, and the participants loved that,” says Baumann.

Happy with how everything turned out, Baumann says, “The top reaction is the technology gods were smiling on us as there were no major glitches and we are very, very, happy for that. I’m a little surprised that everything went so well.”

Benefits of the virtual conference included increased diversity of participants, many who may not have been able to participate otherwise, a reduced carbon footprint, and participants being able to see more talks, since all were recorded. However, Baumann says meeting in-person still can’t be beat.

“This pandemic is particularly hard for early career researchers, like grad students who want to share their research. It’s important to start talking about their research and be in front of people talking about their work. Though responses have been positive, all participants agree on the fact that even the best run virtual conference cannot replace the quality of networking or personal contact that an in-person meeting can deliver.”

Going forward, Baumann says efforts will be made to ensure future conferences have some mixture of both approaches to make sure prospective attendees have their needs met.

“Some participants were really frank in saying they would never be able to attend an in-person meeting far from their own countries. Some could not easily afford the fee for the virtual conference, but we were able to help. Anybody who says, ‘Well, now that we have virtual conferences, the world is on an equal playing field,’ is not seeing the reality that much of the world has not the same resources and internet connectivity than we do here in an institution like UConn.”

Baumann says this is something organizers will have to think carefully about to calibrate, but going forward, scientific conferences may never be quite the same.

Marine Animals Could Be Used to Clean Up Nature’s Big Pollutant: Microplastics

Over the next four years, faculty from the School of Engineering and College of Liberal Arts and Sciences, including marine sciences professors Evan Ward and George McManus, will use a $2 million grant from the National Science Foundation’s Emerging Frontiers in Research and Innovation (EFRI) program to study the use of mussels (bivalves), combined with microplastic-degrading bacteria, to remove microplastics from the discharge of wastewater treatment plants. For more information about this project see

Red Tide Prey Defense is a Costly Business

Postdoctoral investigator Gihong Park and Professor Hans Dam published a study in the Proceedings of the Royal Society B that demonstrates a fitness cost of defense in a red tide dinoflagellate. Organisms must defend themselves against their consumers. It has long been hypothesized that defenses such as toxin production may come at a cost in the form of reduced growth. Yet, demonstrating such costs of defense is challenging. Park and Dam’s study presents a novel approach using a growth-related gene to show that when a red tide dinoflagellate (phytoplankton) is exposed to a copepod grazer, it increases toxin production but decreases its growth gene marker, indicating a fitness cost of toxin production. While costly, the defense is adaptive because it lowers the consumer ingestion rate and it allows the dinoflagellate to persist. The findings have important implications for understanding the factors that control the rise and fall of red tide blooms. Such blooms plague coastal regions wreaking havoc on local fisheries economies and threatening public health.

Link to the paper:

Viruses, the “good”, not the bad or ugly

The viruses may be the missing link in the evaluation of life. Formation of Earth’s oldest ecosystems, stromatolites, requires a deeper understanding of several virus-mediated mechanisms that change the cyanobacterial behavior through geologic time, including the “invention” of oxygen-producing photosynthesis. Cyanobacteria also precipitate and cement the carbonate minerals, a stromatolite is preserved in the fossil record, some for as long as 3,500 million years. Without the interception of viruses, this may not have happened and further evolution of life and biogeochemistry that resulted in the Cambrian explosion would have been different. A planet without humans….?

Mechanisms proposed for virus-cyanobacteria interaction. Image: Richard White III

Marine Sciences graduate student Alec Shub working with Governor’s Council on Climate Change

For the past several months Alec Shub has been working with Connecticut’s Department of Energy and Environmental Protection (DEEP), coordinating reports for the Governor’s Council on Climate Change (GC3). The GC3 was established by executive order, in an effort to mitigate greenhouse gas emissions and address strategies for adaptation and resilience to the impacts of climate change throughout the state of Connecticut. One of the Council’s goals is to help the state meet its target of an 80% reduction in greenhouse gas emissions (below 2001 levels) by 2050. This effort has garnered collaboration between an eclectic team of 23 council members and 230 working group members, including experts from a wide range of scientific disciplines, state agencies, local governments, non-profits, and businesses.  As a result of his work, Alec has learned how different fields are able to come together and collaborate on a central issue.   As a graduate student, Alec volunteered with the Connecticut Institute for Resilience and Climate Adaptation (CIRCA), which was an important stepping stone to the GC3 position.   He also believes the GC3 experience will be invaluable preparation for his upcoming Knauss Fellowship with the National Oceanic and Atmospheric Administration’s (NOAA) Climate Program Office.

If you are interested in learning more about the GC3 or reading any of the working group reports, you can visit the page on the DEEP website:

Christening the Automated Larval Fish Rearing System (ALFiRiS) at the DMS Rankin Lab

Rankin Lab, December 2020. After using and tinkering with our experimental system at the Rankin Seawater Lab of the University of Connecticut’s Department of Marine Sciences for over 5 years, it’s finally time to give the baby a name – ALFiRiS.

Over the past years, the Evolutionary Fish Ecology Lab of Prof. Baumann has built an Automated Larval Fish Rearing System (ALFiRiS) to conduct factorial experiments on the climate sensitivity of fishes. It consists of a 3 x 3 array of recirculating units (600L/150gal) that have independent computer-control over their temperature, oxygen, and pH conditions. We use a self-developed LabView (National Instruments) platform to sequentially monitor tank conditions via industrial-grade oxygen and pH sensors (Hach) and then control gas solenoids (air, N2, CO2) to maintain and modulate environmental conditions. The system can apply static as well as fluctuating conditions on diel and tidal scales. Computerized temperature control further allows simulating heatwaves and other non-static thermal regimes. We’ve only begun to explore all of ALFiRiS’ capabilities.

To learn more, go to

Dierssen Lab Earns Recognition from NASA

Dr. Heidi Dierssen, Professor in Marine Sciences, and her postdoc Brandon Russell were among the individuals recognized by NASA during its 2020 Honor Awards event that was held on December 1. They were part of the Coral Reef Airborne Laboratory Mission Team that collected and  delivered unprecedented data about reef environments.

Brandon Russell

Living in an anoxic world: Arsenic cycling supports life for billion of years

Elaina Hancock – UConn Communications

Much of life on planet Earth today relies on oxygen to exist, but before oxygen was present on our blue planet, lifeforms likely used arsenic instead. These findings are detailed in research published today in Communications Earth and Environment.

A key component of the oxygen cycle is where plants and some types of bacteria essentially take sunlight, water, and CO2, and convert them to carbohydrates and oxygen, which are then cycled and used by other organisms that breathe oxygen. This oxygen serves as a vehicle for electrons, gaining and donating electrons as it powers through the metabolic processes. However, for half of the time life has existed on Earth, there was no oxygen present, and for the first 1.5 billion years, we really don’t how these systems worked, says lead author of the study and UConn Professor of Marine Sciences and Geosciences Pieter Visscher.

Light-driven, photosynthetic organisms appear in the fossil record as layered carbonate rocks called stromatolites dating to around 3.7 billion years ago, says Visscher. Stromatolite mats are deposited over the eons by microbial ecosystems, with each layer holding clues about life at that time. There are contemporary examples of microbes that photosynthesize in the absence of oxygen using a variety of elements to complete the process, however it’s unclear how this happened in the earliest life forms.

Theories as to how life’s processes functioned in the absence of oxygen have mostly relied on hydrogen, sulfur, or iron as the elements that ferried electrons around to fulfill the metabolic needs of organisms.

As Visscher explains, these theories are contested; for example, photosynthesis is possible with iron, but researchers do not find evidence of that in the fossil record before oxygen appeared some 2.4 billion years ago. Hydrogen is mentioned, yet the energetics and competition for hydrogen between different microbes shows it is highly unfeasible.

Arsenic is another theoretical possibility, and evidence for that was found in 2008. Visscher says the link with arsenic was strengthened in 2014 when he and colleagues found evidence of arsenic-based photosynthesis in deep time. To further support their theory, the researchers needed to find a modern analog to study the biogeochemistry and element cycling.

Finding an analog to the conditions on early Earth is a challenge for a number of reasons, besides the fact that oxygen is now abundant. For instance, the evidence shows early microbes captured atmospheric carbon and produced organic matter at a time when volcanic eruptions were frequent, UV light was intense in the absence of the ozone layer, and oceans were essentially a toxic soup.

Another challenging aspect of working within the fossil record, especially those as ancient as some stromatolites, is that there are few left due to the cycling of rock as continents move. However, a breakthrough happened when the team discovered an active microbial mat, currently existing in the harsh conditions in Laguna La Brava in the Atacama Desert in Chile.

The mats have not been studied previously but present an otherworldly set of conditions, like those of early Earth. The mats are in a unique environment which leaves them in a permanent oxygen-free state at high altitude where they are exposed to wild, daily temperature swings, and high UV conditions. The mats serve as powerful and informative tools for truly understanding life in the conditions of early Earth.

Visscher explains, “We started working in Chile, where I found a blood red river. The red sediments are made up by anoxogenic photosynthetic bacteria. The water is very high in arsenic as well. The water that flows over the mats contains hydrogen sulfide that is volcanic in origin and it flows very rapidly over these mats. There is absolutely no oxygen.”

The team also showed that the mats were making carbonate deposits and creating a new generation of stromatolites. The carbonate materials also showed evidence for arsenic cycling – that arsenic is serving as a vehicle for electrons — proving that the microbes are actively metabolizing arsenic, much like oxygen in modern systems. Visscher says these findings, along with the fossil evidence, gives a strong sense of the early conditions of Earth.

“Arsenic-based life has been a question in terms of, does it have biological role or is it just a toxic compound?” says Visscher.

That question appears to be answered: “I have been working with microbial mats for about 35 years or so. This is the only system on Earth where I could find a microbial mat that worked absolutely in the absence of oxygen.”

Visscher points out that an important tool they used to perform this research is similar to one onboard the Mars Perseverance rover, currently en route to Mars.

“In looking for evidence of life on Mars, they will be looking at iron and probably they should be looking at arsenic also.”

This work was supported by grants from NSF grant OCE 1561173, ISITE project UB18016-BGS-IS and the São Paulo Research Foundation FAPESP, grant 2015/16235-2. You can also find out more about this work in The Conversation.