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.
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!
Baumann H. 2022. Why are sand lance embryos so sensitive to future high CO2 oceans? Keynote at the 45th Larval Fish Conference, San Diego 29 Aug - 1 Sep 2022
Zavell, M., Mouland, M., Schultz, E., and Baumann H. 2022. Overwinter growth and energy allocation of Black Sea Bass juveniles from Long Island Sound. 45th Larval Fish Conference, San Diego 29 Aug - 1 Sep 2022
7 June 2022. This is World Ocean Week and many Marine Science students and faculty do their bit to increase outreach to our community. Hannes had the privilege of dropping by the 3rd graders of the Catherine Kolnaski Magnet School, talking about what Marine Scientists do, which ocean critters eat another and "What was the weirdest fish you ever caught?" Oh, and "Are you really sure that the Megalodon [Charchardon megalodon] is no longer alive?" Thank you to Mr. Moon, Mrs. Laudone for the opportunity to come visit the school!
May 7th, 2022. Despite the chilly, rainy weather on Hammonassett Park's Meigs Point and the resultant lack of a beach crowd, the mood among the group was elated and proud. For over two years, our lab together with researchers from the Connecticut Department of Energy and Environmental Protection (CTDEEP, Tom Savoy, Jacque Benway) have worked tirelessly to better understand the growth and seasonal movement patterns of Atlantic Sturgeon (Acipenser oxyrhynchus) in Long Island Sound and the Connecticut River. The research project was funded by Connecticut SeaGrant (NOAA Award NA18OAR4170081, Project R/LR-29).
Kelli Mosca did her M.S. thesis research using fin spine sections for growth analyses and telemetry data for movement patterns. After defending in March 2022, she immediately accepted an offer by CTDEEP to become a full time staff scientist. Congrats again, Kelli!
The sign was designed by Joe Cunningham with pictures from Jacob Snyder (RedSkiesPhotography.com). It combines several outreach goals. 1) Convey to people that these ancient, iconic fish actually occur in our waters, 2) teach the interested readers that sturgeon spawn in freshwater and then grow up in saltwater, 3) give readers a sense of the ongoing research on Atlantic sturgeon, 4) tell the public that sturgeon may come back to Long Island Sound and River, but need protection. Particularly, they rely on any accidental catches to be released and reported. The sign is also available in Spanish language to broaden its reach.
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.”
21 March 2022. Today, Baumann lab graduate student Kelli Mosca presented her Masters thesis entitled "Atlantic sturgeon (Acipenser oxyrinchus) Growth and Habitat Use in the Connecticut River and Long Island Sound". She did a marvelous job summarizing the multifaceted findings on age and growth of Atlantic sturgeon in the eastern Long Island Sound and the Connecticut River, their movement patterns based on analyses of acoustic telemetry data, while evaluating the evidence for indications that Atlantic sturgeon may utilize the Connecticut River again for spawning.
Kelli was an inspirational and cherished member of the Baumann lab, who literally mastered the challenges of being a 'whole-pandemic' Master student. Her dedication and continued work for CTDEEP were awarded by an offer for a CTDEEP Fishery Biologist I position, which she has wholeheartedly accepted. Congratulations Kelli, and all the best for the next steps in your career!
The UConn Department of Marine Sciences Presents a Master’s Thesis Presentation by
Kelli Mosca B.S., University of New Haven, 2017
12:00 p.m., Monday, March 21, 2022 Lowell Weicker Building, Seminar Room 103 or Via WebEx
Atlantic sturgeon (Acipenser oxyrinchus) Growth and Habitat Use in the Connecticut River and Long Island Sound
Atlantic sturgeon (ATS, Acipenser oxyrinchus) are long-lived, anadromous, and endangered fish with a wide geographical distribution along the east coast of North America. Historically known to spawn in numerous rivers, many spawning runs ended due to intense fishing pressure and habitat obstruction in the 19th and 20th centuries. This was thought to be true for the longest river in the US Northeast, the Connecticut River, until pre-migratory ATS juveniles appeared in the river in 2014. Here, I use a long-term archive of fin spine samples and three years of acoustically tagged ATS to generally expand knowledge about the ATS using the CT River and LIS, and specifically examine these empirical data for potential evidence of re-emergent spawning behavior. I analyzed 301 sections of ATS fins spines collected from 1988-2021 to determine age, annuli widths, and thus population- and individual-based growth patterns. I found that the vast majority of ATS in my study area were juveniles and sub-adults with an average (± SD) age of 7.5 ± 3.1 years and an average (± SD) length of 101 ± 26 cm. The weighed, population-based Von Bertalanffy growth model estimated a K of 0.08 (95% CL, 0.01/0.17) and a L∞ of 171.2 cm (95% CI, 129/547 cm), the latter likely showing signs of missing large adults. K and L∞ distributions showed no sign of sex-specific multi-modality. Longitudinal length back-calculations revealed the selective disappearance of faster growing phenotypes (at ages 2-6) with increasing age at capture, which is clear evidence for Lee’s phenomenon. Acoustic detections of telemetered Atlantic sturgeon (2019-2021) revealed that most sturgeon in 2019 and 2020 utilized the Lower CT River (brackish water), whereas in 2021 detections were highest in LIS (salt water). Detections in the Upper CT River (freshwater) were common but much less dense across years, with 53%, 69% and 45% of ATS detected in the Upper CT River at some point in each season (2019-2021 respectively). I found a positive relationship of fish proportion in the CT River with temperature, but an inverse relationship of fish proportion in the CT River with river discharge. On average, the arrival of fish in the CT River occurred in June, when water temperatures were 17.5 - 24.9 ºC, while the departure from the CT River generally occurred in October, coinciding with river temperatures of 15.2 - 20.4 ºC. Some of the fish utilizing the Upper CT River made directed movements to a potential spawning ground at Portland, CT (river km 47). However, these movements occurred in mid- to late August (12th -23rd), which is inconsistent with the typical spring timing of ATS spawning runs in northern populations. Fall spawning runs are only known for southern ATS populations. In addition to timing, ATS sizes in the Upper CT River also do not support spawning behavior, because fish of all sizes (72 – 154 cm TL) and ages (3-15) visited the Portland area for 0.25 – 63.25 days. I conclude that neither age nor telemetry data support the re-emergence of the CT River as an ATS spawning ground. Future work will benefit from a more even sampling of gear sizes and should examine possible explanations for ATS freshwater utilization including feeding and individual preferences.
Major Advisor: Hannes Baumann
Associate Advisor: Eric Schultz
Associate Advisor: Tom Savoy
Associate Advisor: Jacque Benway
Associate Advisor: Catherine Matassa
Monday, November 22nd 2021. Big and heartfelt congratulations to Lucas Jones, who presented his Master thesis to his peers at the institute and colleagues national and international. Well done, Lucas!
A link to his recorded presentation will be posted here soon.
The UConn Department of Marine Sciences
Presents a Master’s Thesis Presentation by
B.A., University of Connecticut, 2018
4:00 p.m., Monday, November 22, 2021
Marine Sciences Building, Seminar Room 103
Using Low-Coverage, Whole Genome Sequencing to Study Northern Sand Lance (Ammodytes dubius) Population Connectivity in the Northwest Atlantic
Northern sand lance (Ammodytes dubius) are key forage fish in Northwest Atlantic (NWA) shelf ecosystems, where they exclusively occur on coarse-grain, offshore sand banks. This patchy occurrence may result in genetically more fragmented, less connected populations, but traditional morphological or genomic approaches have so far been unsuccessful in fully resolving the species’ population structure and connectivity. My study pursued an alternative genomic approach, using low-coverage, whole genome sequencing (LcWGS) to address these important questions. I extracted DNA from 273 A.dubius specimens collected by collaborators from sevenregions across the species geographical range, from Greenland to New Jersey, USA. From LcWGS data, I identified 11,558,126 single nucleotide polymorphisms (SNPs) that allowed quantifying genetic differentiation between populations (FST), thereby revealing the genetic structuring of populations throughout the NWA. Despite the potentially homogenizing influence of the general north to south ocean circulation, I found a clear genetic break around Nova Scotia that delineated a northern from a southern A. dubius supergroup. Only within the southern supergroup, genetic distances increased with the geographic distance between sample sites. At the focal site of Stellwagen Bank (southern Gulf of Maine), A. dubius samples collected over several years (2014 – 2019) revealed small but significant temporal genetic differences that imply varying occupation of this offshore habitat by genetically different sand lance contingents. Inclusion of samples from the inshore congener A. americanus confirmed the clear genetic separation between both species and further determined that all sand lance caught on Stellwagen Bank are exclusively A. dubius. Overall, my work suggests the existence of two spatially distinct A. dubius populations with little ‘realized’ connectivity, which is critical knowledge to aid protection and management of offshore marine resources.
2 November 2021. We are happy report that the ICES Journal of Marine Science just published the last major experimental paper on Atlantic silverside CO2-sensitivity from our lab. Callie Concannon and co-authors report on two complementary, long-term rearing trials in 2015/16 and 2018/19, where silverside juveniles or newly fertilized embryos were reared under contrasting temperature and CO2 conditions to maturity. This revealed negative effects of high CO2 conditions on female fecundity, but only at the warm, not the cold temperature treatments (Fig. below). Our study and its data are novel, because they were generated by the first whole-life CO2 rearing experiment of a fish and are the first empirical fecundity effects shown for a broadcast-spawning fish species.
The paper is also special to us, because its publication marks the erstwhile conclusion of our yearlong, NSF-funded efforts (OCE#1536165) to understand the CO2 sensitivity and its mechanisms in this important forage fish and long-standing model in fish ecology and evolution. The project ran from 2015 - 2020, produced 15 publications, 2 book chapters, and over 40 presentations, while furthering the careers of a post-doc, a PhD student, 5 Master students and over 10 undergraduates.
Reposted from UConn Today | August 26, 2021 | By Elaina Hancock
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 just 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.
Groton, CT 24-26 June 2021. The long awaited and anxiously prepared virtual 44th Larval Fish Conference was held, featuring more than 240 participants from 28 countries. 58 scientific talks, including 3 keynote lectures were given via Cisco’s WebEx platform, whereas networking activities such as poster presentations, ‘Meet the Speaker’ events, and Mentor hours used the innovative Gatherly platform. The technology was working out well, the preparation paid off, and delegates were overall enthusiastic about this virtual alternative, which was forced on us by Covid-19, but may have shown us new ways and concepts to broaden the societies reach and equality.
Special thanks go to the scientific steering committee Eric Schultz, Jacqueline Webb, and Paul Anderson. Lauren Schaller, Anne Hill, Harley Erickson, and Kate Copeland from UConn’s conference services did a great job as well preparing and running parts of the events. Support came from NOAA’s Northeast Fisheries Science Center.