18 June 2022. We are happy to report that our genomic silverside experiment has progressed from "Can we really pull this off?" to "We think we just might" over the past weeks. The silverside larvae of these different crosses show stunning size variability, between populations and temperatures. We already obtained two early life mortality estimates and lots of genetic material, including a full set of crosses reared at 26C and ad libitum food, reaching 20 mm in roughly 4 weeks post hatch. Fingers crossed for the rest of the rearing time.
29 May 2022. When in a few months researchers and students at the Bermuda Institute of Ocean Science (BIOS) begin using their new outdoor mesocosm facility, they can now manipulate and control the CO2 levels in as many of 9 flow-through basins. The important new capacity of the system will allow realistic ocean warming and acidification experiments and has been the product of a wonderful collaboration between BIOS researcher Dr. Yvonne Sawall and our UConn Marine Sciences team consisting of John Hamilton and Hannes Baumann.
The newly developed system shares some of the design ideas with ALFiRiS, the factorial rearing system we developed and used over the past years at UConn's Rankin Seawater Lab. For example, we again developed and installed a central pH measurement hub that sequentially collects water samples via pumps from each of 12 independent basins, which is advantageous, because it only relies on a single, high-end pH sensor, therefore making measurements always comparable. Similarly, we are using LabView software (National Instruments) to switch pumps on and off and log, display, and graph the pH conditions in real time for researchers to have confidence in their chosen environmental parameters.
While most of the planning and design work was done remotely via frequent online meetings, Hannes and John worked with Yvonne during the past week at the BIOS station on installing and testing the systems major components. Working mostly out in the open under a warm and clear Bermudan sky was a particular treat of this assignment. Big shout-out, too, to facilities manager Kevin Hollis for his tireless onsite help!
Despite setbacks in form of supply chain delays and an unfortunate last moment COVID infection preventing team member Lucas Jones from traveling to Bermuda, soon the new outdoor mesocosm facility at BIOS will become operational and allow new and advanced kinds of experimental research on global change biology.
A first test of our flow cell
15 May 2022. A full, blood red moon rises over Pine Island this Sunday evening. The sight makes not just humans swoon – its pull extents underwater to all kinds of critters that take it as cue for reproduction. Critters just like the Atlantic Silverside, which once again we pursue this season to extract more of its genomic 'secrets'.
Specifically, it is this weekend that we embark on yet another ambitious road trip to find and sample spawning-ripe silversides from two very far apart places: Morehead City, North Carolina and Beverly, Massachusetts. The goal: transport spawners live from each population to UConn's Rankin Seawater lab and produce calculated crosses that will allow studying the role of genomic inversions in local adaptation.
The crew this time are Maria Akopyan and Jessica Rick from Cornell University, along with Lucas Jones and Hannes Baumann from UConn. Big shout-out to Tara Duffy for her help with beach seining at Beverly, MA. During the spawning event on May 15th, Nina Therkildsen also joined the efforts. The design and experiment are part of Jessi's successful NSF post-doctoral fellowship proposal, which the whole UConn-Cornell silverside team supports.
Click through the pictures below to retrace the steps of an exhausting but so far successful effort. Fingers crossed that all goes well during the next weeks, when the fish need to hatch, survive and grow, so they can be assessed for their traits.
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.
A potential ripple effect from carbon in the atmosphere could have severe impacts throughout the ocean ecosystem
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
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
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
4 March 2022. Hannes was the invited speaker at today's Friday seminar of the Department of Marine Sciences. His talk gave an overview of the research highlights of our multi-disciplinary and multi-institutional efforts to better understand basic ecological facts, population connectivity & structure, and the unusually high CO2-sensitivity of sand lance embryos. The remotely given presentation was attended by 62 people, some of which listened in from as far away as Norway!
The talk was recorded and can be accessed via the public link below.
- Baumann, H. 2022. The unusual ecology & climate sensitivity of sand lance, a key forage fish on the Northwest-Atlantic shelf. UConn Marine Sciences Friday seminar. Online. 4 March 2022.
The unusual ecology and climate sensitivity of sand lance, a key forage fish on the Northwest-Atlantic Shelf
No matter how you look at these small, slender-bodied fishes that at times live buried in sediment or emerge as dense pelagic schools, northern sand lance (Ammodytes dubius) easily awe even the most hard-to-impress scientist or naturalist. Their unusual behavior, patchy occurrence, and reproductive timing are paralleled by their extraordinary importance as forage fish that sustain well-known hotspots of iconic predators (cod, tuna, sharks, seabirds, whales) all across the Northwest Atlantic shelf. And yet, despite their recognized role as the ‘backbone’ of many shelf ecosystems, we still don’t understand many basic aspects of sand lance ecology, population structure and their vulnerability to manmade climate change. Over the past years, our lab has been working alongside other US and Canadian research groups on multiple sand lance projects that have produced stunning new insights into these enigmatic fish. This seminar will outline some of the highlights. We discovered that the seasonal growth of these fish relies heavily on the lipid-rich copepod Calanus finmarchicus and showed that after a dormancy period in summer they spawn on Stellwagen Bank for just a brief period at the end of fall. To resolve questions of connectivity between sand lance areas, we performed large-scale Lagrangian drift simulations that suggested areas of high, low and negligible retention of sand lance offspring and showed overlaps with planned offshore wind lease areas. A large collaborative effort succeeded in obtaining specimens from across the entire distributional range (Greenland to Mid-Atlantic Bight), and subsequent whole genome sequencing newly revealed a stark genomic differentiation between northern and southern population clusters. Last, we performed multiple years of rearing experiments on embryos that consistently showed an unusual sensitivity of sand lance to future, high CO2 oceans. When coupled with regional, end-of-century pCO2 projections we estimate that rising CO2 levels alone could reduce sand lance hatching success to 71% in 2100 relative to today. Warming, acidification, and habitat exploitation therefore emerge as key factors lining up against the future productivity of this forage fish, which is so critically important across Northwest-Atlantic shelf ecosystems.
Video: A November day on Stellwagen Bank
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."
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.
Major Advisor: Hannes Baumann
Associate Advisor: Nina Overgaard Therkildsen
Associate Advisor: Senjie Lin
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.
- Concannon, C.A.*, Cross, E.L., Jones, L.F., Murray, C.S., Matassa, C. McBride, R.S., and Baumann, H.
Temperature-dependent effects on fecundity in a serial broadcast spawning fish after whole-life high-CO2 exposure
ICES Journal of Marine Science fsab217 (published 2 November 2021)