Author: Hannes Baumann

TAFS publishes our first Black Sea Bass experiment paper!

Posted on December 28, 2023December 28, 2023 by Hannes Baumann

27 December 2023. We are excited to announce that Transactions of the American Fisheries Society just published our first large experimental study on Black Sea Bass overwintering! The work is part of Max Zavell's PhD research and reports on temperature- and food-ration dependent overwinter growth in Black Sea Bass juveniles from Long Island Sound. We reared juveniles individually in two separate experiments, one applying three static temperature treatments (6, 12, 19°C) and another using a seasonal temperature profile to mimic the thermal experience of juveniles emigrating to their offshore overwintering grounds coupled with various food treatments.

We found that Black Sea Bass juveniles showed positive overwinter growth even at temperatures as low as 6°C. However, the best temperature for growth, survival, and lipid accumulation was 12°C, which is close to the presumed conditions at offshore overwintering habitats of this species.

Congratulations, Max, to this great paper! Also, congrats to undergraduate student Matthew Mouland, who helped tirelessly with the rearing and has now deservedly become a co-author.

New 2023 sand lance experiment under way!

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

By Lucas Jones.

November 26, 2023. Members of the Sand lance Mafia assembled onboard the F/V Miss Emily in hopes of finding spawning ripe fish for our 2023 experiment. After loading our gear, Captain Kevin navigated us towards the southwest corner of Stellwagen Bank and deployed our beam trawl for our first 10-minute tow.

Boom! From the first tow, fish in spawning condition were brought on board, counted and separated by sex. Now, we just needed to repeat this for 13 more trawls until we had a sufficient amount of fish to start the experiment. After collecting 40+ spawning ripe males and females, we headed back to port wile starting to strip-spawn. This is an all hands on deck process, where we need to work together to evaluate the fish in real time and use the most ripe fish available.

The successful strip-spawn event now marks the start of our most ambitious experiment to date, where DNA and RNA samples will help us further investigate potential mechanisms behind the sand lances high CO2 sensitivity.

UConn Today reports on Hannes’ Chile research

Posted on October 16, 2023October 16, 2023 by Hannes Baumann

October 12, 2023 | Elaina Hancock - UConn Communications

Snap Shot: How Will Organisms Adapt to Climate Change?

A UConn Marine Sciences researcher is spending time in Chile studying an important forage fish, and how this vital part of the food chain will adapt to a changing climate

13 - Pude — The rocky and picturesque shores of the Pacific near Dichato

The world’s oceans have experienced record heat in 2023. With rising temperatures and increasing acidification, we don’t yet know the full extent these changes will have on marine ecosystems.

UConn Department of Marine Sciences Associate Professor Hannes Baumann studies fish, including important forage fishes such as sand lance and silverside, to see how they adapt to changes in environmental conditions. Many species are already adapted to temperature gradients that exist across latitudes on Earth, and Baumann believes that from these patterns, we can learn how fish may adapt to climate change – in time. This so-called “Space-for-Time” approach is one tool scientists use to predict the long-term consequences of climate change.

As part of his post-doctoral work, Baumann experimentally found similar climate adaptation patterns in Atlantic and Pacific silversides. He suspects that a higher-order relationship exists between the strength of adaptation and the strength of the underlying climate gradient.

Now, with a grant from the National Science Foundation, Baumann has the opportunity to return to and expand his study of silversides to a South Pacific species and study how they are adapted to their coastal latitudinal temperature gradient.

“We are hoping the prove the validity of a principle of evolutionary adaptation for the Southern Hemisphere. It will then allow us to compare and integrate the patterns with the silverside species from the Northern Hemisphere, which evolutionary ecologists have been studying for decades already,” says Baumann.

After a two-week proof-of-concept trip to Chile in the Fall of 2022, Baumann established connections with local fishermen and colleagues at the Universidad de Concepcion in Dichato, Chile.

“To get spawning fish, we visit fish markets – called here caletas de pescadores – and first establish a connection to those who make a living catching silversides (“pejerrey del mar”). We’re making friends to explain our unusual request to accompany a fisherman during the night. This is the best method to make sure that the eggs get fully fertilized," he says.

In the Summer of 2023, Baumann began his yearlong sabbatical and has now moved to Chile for five months to begin the main experimental work on Chilean silversides, their adaptations, and the strength of those adaptations to underlying climate change.

01 - HB-Tongoy — Hannes in Tongoy near Coquimbo/Chile

Hannes starts sabbatical research in Chile

Posted on July 22, 2023August 12, 2023 by Hannes Baumann

NSF awards our collaborative sand lance grant!

Posted on June 24, 2023June 24, 2023 by Hannes Baumann

24 June 2023. We are overjoyed to be able to announce today that NSF's Division of Integrative Organismal Systems has awarded our proposed research to better understand sand lance CO2 sensitivity!

With a sense of pride and humility we will take on this intriguing case, follow it down some rabbit holes, while keeping in mind the big picture. This fall, our collaborative team will begin its renewed work, now on both congeneric sandlance species (Ammodytes dubius, A. americanus).

We already have two talented PhD students recruited to the task, Lucas Jones and Emma Siegfried. With curiosity and anticipation, we look forward to the next years of eco-evolutionary research on some of the most important forage fish species on the Northwest Atlantic Shelf.

Public Award Abstract
Ocean warming and acidification are direct, predictable consequences of man-made climate change with likely vast but still insufficiently understood consequences for marine life.

So far, most tested fish species appear only mildly sensitive to ocean acidification, but sand lances are an exception. Sand lances are small, eel-like, schooling fishes of enormous importance as food for marine fish, seabirds and mammals in temperate to polar ecosystems, and recent research conclusively demonstrated that many sand lance embryos have trouble developing and hatching under predicted future ocean conditions.

This project uses modern experimental and molecular tools to understand exactly WHY sand lance embryos are so unusually sensitive and which genes and enzymes are responsible for this. Genes will also reveal whether some specific genotypes are less sensitive to warming and acidification, which can then be used to predict whether the species could evolve to be more tolerant over time.

Another important objective is to test a closely related sand lance species to find out, whether the high climate sensitivity might be of general concern in this important group of forage fishes. This project combines innovative ecological, evolutionary, and genomic research to help society anticipate looming marine ecosystem changes in the 21st century, while equipping the next generation of scientists with the needed tools and expertise to succeed in the challenges ahead.

The project also creates opportunities for high school students from underprivileged Connecticut schools to accompany the team on sand lance sampling trips to Stellwagen Bank National Marine Sanctuary.

Technical Award Abstract
Two recent studies on Northern sand lance (Ammodytes dubius), a key forage fish on offshore sand banks across the Northwest Atlantic shelf (NWA), have robustly demonstrated that predicted future CO₂ conditions induce some of the most severe reductions in embryo survival and hatching success seen yet among tested fish species. This project has four objectives for revealing the mechanisms underpinning this unusual, high CO₂-sensitivity as well as the ubiquity and genetic basis of this phenomenon.

[1] For the first time, we will rear A. dubius offspring produced from wild spawners to late larval stages at factorial CO₂ × temperature conditions to test whether sand lance larvae are as CO₂-sensitive as embryos.

[2] For the first time, we will use transcriptomic tools (RNAseq, RT-qPCR) to elucidate mechanisms causing ‘CO₂-impaired hatching’, focusing specifically on hatching enzymes, to better understand a newly discovered mortality mechanism due to high CO2 in fishes.

[3] Modern genomic approaches (low-coverage whole genome sequencing; allele frequency shifts, relatedness analyses) will reveal whether high CO₂-sensitivity has a genetic basis in sand lance and could therefore evolve.

[4] And for the first time, we will extend CO₂ × temperature experiments to a congener, the American sand lance (A. americanus), which provides an important scientific contrast between nearshore vs. offshore species CO2-sensitivities and will yield critical insights whether high CO₂-sensitivity is a wider concern within the sand lance family.

Feeling the pulse of Mumford Cove

Posted on March 23, 2023March 23, 2023 by Hannes Baumann

23 March 2023. For almost 8 years now, the Evolutionary Fish Ecology Lab has conducted research in nearby Mumford Cove, a small, eelgrass covered embayment on eastern Long Island Sound. Using a set of battery-powered probes we have continuously measured temperature, pH, oxygen, salinity, and depth in 30 min intervals in the Cove - almost 120,000 times. This ongoing effort is not funded by any grant or institution; instead, it has been sustained over all these years by the firm belief in the prescient, if undervalued societal service of monitoring, an activity without short-term reward but important long-term benefits in understanding how ecosystems change on short and long time-scales. To commemorate the effort, we simply thought that it is time to show you some data, some pictures, and draw some early, cautious conclusions about the very interesting case of Mumford Cove. Have a look!

ICES JMS publishes sand lance population structure paper!

Posted on December 9, 2022February 3, 2023 by Hannes Baumann

5 December 2022. We are proud to announce that the ICES Journal of Marine Science just published our latest sand lance study! The work spearheaded by Lucas Jones and subject of his Masters thesis research has brought together a large, international group of collaborators to better understand the genetic relationships between disparate sand lance populations across their large geographical range. This is an Open Access publication that will hopefully be of use to researchers studying sand lance everywhere.

Jones, L.F., Lou, R.N., Murray, C.S., Robert, D., Bourne, C.M., Bouchard, C., Kučka, M., Chan, Y.F., Carlon, D.B., Wiley, D.N., Therkildsen, N.O., and Baumann, H. (2022) Two distinct population clusters of Northern sand lance (Ammodytes dubius) on the Northwest Atlantic shelf revealed by whole genome sequencing ICES Journal of Marine Science 80:122-132

Press release. By Elaina Hancock

Genetic Barriers, a Warming Ocean, and the Uncertain Future for an Important Forage Fish

In the vast oceans, one would assume their inhabitants can travel far and wide and, as a result, populations of a species would mix freely. But this doesn’t appear to be the case for a vital forage fish called the sand lance.

Sand lance are small schooling fish impressively rich in lipids, which makes them a fantastic and significant food source for at least 70 different species ranging from whales and sharks to seabirds, says UConn Associate Professor of Marine Sciences Hannes Baumann.

The Northern sand lance can be found from the waters off New Jersey all the way north to Greenland. Researchers, including Baumann and Ph.D. student Lucas Jones, were interested to see if sand lance constitute a massive, homogenous population, or whether there are genetically distinct groups. Their findings are published in the ICES Journal of Marine Science.

Baumann explains these are important questions to answer when considering conservation and sustainable management of the species, especially since the regions where sand lance live are warming faster than many areas of the planet due to climate change.

Sampling fish from such a broad range is no small task, but two years ago, Baumann and Jones began reaching out to other researchers to see if they had tissue samples to spare. Baumann credits the work to the international group of colleagues who contributed samples including co-authors from Canada and Greenland, and who helped sequence and analyze the data including co-authors from Cornell University.

In all, Baumann, Jones, and the team were able to sequence and analyze nearly 300 samples from a variety of locations across the sand lance’s range using a technique called low-coverage whole genome sequencing. They also sequenced the first reference genome for sand lance.

In a nutshell, Baumann says they found an area on the Scotian Shelf, off the coast of Nova Scotia, where a genetic break occurs. The researchers distinguished two distinct groups, one north and one south of the divide, with parts of the genome differing quite dramatically – namely on chromosomes 21 and 24. Without obvious physical barriers like a mountain range separating the groups, Baumann says it’s logical to ask how these differences are possible.

“That is the scientific conundrum,” says Baumann, and the answer, it appears, lies in the currents.

“When fish from the north reproduce and drift south, they are genetically less adapted to warmer southern waters, even if it’s five or six degrees warmer in the winter, they are just not surviving,” Baumann says. “These populations may be linked by the ocean currents, but the realized connectivity is basically zero.”

This finding is a first for the sand lance, but it has been shown in other species such as lobsters, cod, and scallops, and this research adds further evidence to an apparent temperature divide at the Scotian Shelf, and helps demonstrate that temperature is an important factor in survival.

“Example after example shows that the ocean is not as homogeneous a place as expected, and there are all kinds of things that prevent that constant mixing,”Baumann says. “We found another striking example of that.”

When researchers find adaptation in an environment where mixing is continuous, like in the ocean, Baumann says, the question is how it is possible that groups stay different, even though they are constantly encountering other genotypes. That is where powerful genomic methods, like the ones used in this paper, come in handy.

“Parts of the genome in many species have what we call a ‘genetic inversion,’ which means that the genes on the chromosome from one parent have a certain order and the genes on the same chromosome that come from the other parent that code for the same thing, and they’re the same area, but they’re flipped,” Baumann says.

These inversions mean recombination cannot occur; therefore, the genes are passed down through the generations and play an important role in adaptation.

“We discovered on chromosomes 21 and 24 there are whole regions that are completely different and that is like the trademark signature of what we call an inversion because there’s no recombination going on.”

Baumann says that knowing there are genetic and ecological barriers on the Scotian Shelf is important, because with climate change, this barrier may move north and while that may be good news for southern fish, it’s bad news for the fish currently there.

The researchers were also a little relieved in finding two clusters, because had there been many smaller clusters, it could make management and conservation more challenging, especially considering scenarios like the construction of offshore wind parks. Areas potentially well situated for wind turbines can also be habitats for sand lance, and construction disrupts habitats. If there were many, smaller population clusters, a single construction project could pose the risk of completely wiping out a cluster, whereas with more widely dispersed populations, though the local population may be temporarily disturbed, it will not be long before they are able to re-establish after construction is completed.

Baumann plans to focus further research on studying the genetic basis of the thermal divide.

“We want to make sure that this fish is productive and resilient, despite climate change, so we should make sure these areas where they are occurring are protected,” Bauman says. “These decisions should include experts to ensure if there’s an area that is very critical to sand lance, that any disturbance is temporary.”

It isn’t an unsolvable conflict, but it is something that we need to do, says Baumann, who also notes that it is possible that sand lance north of the thermal divide are already suffering more from warming because the region is warming faster.

“It could be that these two clusters have different vulnerabilities to climate change,” he says. “We don’t know that yet but that’s something that should be pursued.”

Fishing for silversides … in Chile!

Posted on October 13, 2022October 15, 2022 by Hannes Baumann

Concepcion (Chile), 12 October 2022. Two incredible weeks of adventure and scientific exploration for new and potentially groundbreaking science are coming to a close. In preparation for next year’s sabbatical, Hannes has met and made friends with colleagues at the Universidad the Concepción in southern Chile, travelled some 2,000 miles along the stunning Chilean coast, scoured local fish markets and accompanied artisanal fishermen on their nightly pursuits. The goal: finding a small fish that looks all too familiar – a silverside!

The Chilean silverside (Odontesthes regia), locally known as ‘pejerrey’, looks eerily similar to the Atlantic silverside (Menidia menidia), the model that has already inspired decades of eco-evolutionary research across many labs including ours. And like its northern hemisphere cousin, Chilean silversides occur over an astounding geographical range along the South American Pacific coast, all the way from Puerto Montt (42°S) to southern Peru (10°S)! There, average coastal temperatures change predictably with latitude and therefore provide a natural climate gradient in space that could serve as an analogue to climate change in time. Whether and how Chilean silversides show similar local adaptations to their latitudinal gradient is a big question – and next year’s sabbatical will start to provide some important answers.

To prepare, Hannes spent two weeks in September and October 2022 in Chile. Hosted by the ever-enthusiastic Prof. Mauricio Urbina from the zoology department and thanks to a visiting grant from the university, we were ready to start exploring. Our specific goal for this trip was to find spawning-ripe pejerrey in two of the planned four locations along the coast.

The luck was on our side and the timing of the visit turned out to be perfect. On a nightly fishing trip with the artisanal fisherman Juan Figueroa from the small village of Tumbes near Concepción, we caught running ripe males and females, observed naturally deposited egg masses in nearshore waters, and were able to subsequently document the temperature-dependent development of newly fertilized embryos.

On an epic road-trip up the coast all the way to Coquimbo, Hannes and graduate student Rocio Barrios stopped at many villages and local fish markets, gathering information and finally securing precious samples of spawning-ripe pejerrey from a fisherman at the Coquimbo fish market. Transporting the embryos was a success, too, thereby paving the way for the proposed research plan next year.

The real, big common garden experiments will take place from September – December 2023 at the Dichato Marine Station near Concepción, a small but recently renovated station with excellent facilities for our purposes.

Hannes & Max at the 45th Larval Fish Conference in San Diego

Posted on September 7, 2022September 13, 2022 by Hannes Baumann

2 September 2022. After two grueling years of pandemic restrictions, Zoom conferences and meetings, the Baumann lab was as elated as anyone else to attend the first in-person conference again! Hannes & Max went to beautiful La Jolla in San Diego to participate in this years 45th Larval Fish Conference (Aug 29 - Sep 2). The stunning setting of the Scripps campus amidst the sound of the Pacific Ocean breeze provided the right kind of backdrop to again mingle with colleagues, meet fellow graduate students for scientific and just fun discussions, while an eclectic number of talks across the spectrum of Larval Fish and Larval Biology renewed the inspiration for our science. Hannes gave a keynote about our recently published work on sand lance CO₂ sensitivity, while Max presented his first conference talk about juvenile Black Sea Bass growth and energy allocation.

A big, heartfelt thanks to Noelle Bowlin (NOAA) and her team for pulling off this remarkable conference during these still uncertain, post-COVID times!

NCMA2022 experiment update: Phenotyping 1,147 fish

Posted on July 24, 2022July 28, 2022 by Hannes Baumann

Groton, 24 July 2022. A remarkable week ends with a sense of pride, accomplishment and a good dose of exhaustion. After more than two months of rearing, the silversides from our crosses in May have grown big, and at least for the warm, 26C treatment, they reached their final, intended size (~40 mm). Our rearing job came to a successful end, and now post-doctoral researcher Jessica Rick and PhD-student Maria Akopyan came back to the Rankin Lab equipped with hundreds of tubes and lots of RNAlater to finalize the sampling. This involved measuring the critical sustained swim speed of every individual fish, followed by meticulous measurements, photographs, and eventually an individual tube for preservation in RNAlater. Over the course of 9 days (and over 10h of work each day), the team measured 1,147 fish, which ranged in size between 15 and 50 mm. A big hat tip to the hard-working geneticists!

Evolutionary Fish Ecology

Author: Hannes Baumann

TAFS publishes our first Black Sea Bass experiment paper!

New 2023 sand lance experiment under way!

UConn Today reports on Hannes’ Chile research

Snap Shot: How Will Organisms Adapt to Climate Change?

Hannes starts sabbatical research in Chile

NSF awards our collaborative sand lance grant!

NSF-ORCC (Organismal Response to Climate Change): Collaborative Research: Mechanisms underpinning the unusual, high CO₂ sensitivity of sand lances, key forage fishes on the Northwest Atlantic Shelf (#2307813, 2023-2026, $1,050,000)

Feeling the pulse of Mumford Cove

ICES JMS publishes sand lance population structure paper!

Genetic Barriers, a Warming Ocean, and the Uncertain Future for an Important Forage Fish

Separation of 3 sand lance species based nuclear and mitochondrial DNA (Jones et al. ICES JMS 2022)

Fishing for silversides … in Chile!

Hannes & Max at the 45th Larval Fish Conference in San Diego

NCMA2022 experiment update: Phenotyping 1,147 fish

Snap Shot: How Will Organisms Adapt to Climate Change?

NSF-ORCC (Organismal Response to Climate Change): Collaborative Research: Mechanisms underpinning the unusual, high CO2 sensitivity of sand lances, key forage fishes on the Northwest Atlantic Shelf (#2307813, 2023-2026, $1,050,000)

Genetic Barriers, a Warming Ocean, and the Uncertain Future for an Important Forage Fish

Separation of 3 sand lance species based nuclear and mitochondrial DNA (Jones et al. ICES JMS 2022)

NSF-ORCC (Organismal Response to Climate Change): Collaborative Research: Mechanisms underpinning the unusual, high CO₂ sensitivity of sand lances, key forage fishes on the Northwest Atlantic Shelf (#2307813, 2023-2026, $1,050,000)