[Research feature] Our multistressor NSF project in the spotlight

This research feature makes the case for multistressor research to a broad general audience and introduces our NSF project and its participants. Download the feature by clicking on the pictures or the link below.


[Research news] Are sand lance embryos particularly sensitive to high CO2?

This article has been cross-posted at news sites of Connecticut SeaGrant, Stellwagen Bank National Marine Sanctuary, and the Early Life History Section of the American Fisheries Society.

By Hannes Baumann

On this dimly lit November afternoon, rain mercilessly drenched scientists and crew on board the R/V Auk as it slowly navigated the waters of Stellwagen Bank. A world like a wet sponge. Sky and ocean, indistinguishable.

Thanksgiving, the next day.

Despite the circumstances, the team’s mood was nothing short of elated. Our small beam trawl had just spilled hundreds of silvery fish on deck, wriggling like eels. They were Northern sand lance (Ammodytes dubius).

Running ripe adults.


Apparently, they like Thanksgiving, too.


As the ship docked back in the Scituate, Mass., harbor that day, the rain thinned to hazy darkness.

“Let’s get a coffee and then on the road,” mumbled Chris, who led the team, “the real work of the experiments has just begun.”

Chris RV Auk Sediment grab
Chris Murray, a member of the research team, checks the contents of a sediment grab for sand lance. Photo: Jacob Snyder / Red Skies Photography

The RV Auk in early morning, getting ready for another sand lance sampling trip to Stellwagen Bank. Photo: Hannes Baumann
Stellwagen Bank, the National Marine Sanctuary just north of Cape Cod, is a true hotspot for some of the Atlantic Ocean’s most iconic creatures: whales, seals, tuna and seabirds, who all share a particular appetite for this one fish – sand lance. Some experts in the sanctuary’s ecosystem call this species its “backbone.” Others consider it a classic forage fish, responsible for transferring massive amounts of energy from lower to upper levels on the food chain.

Sand lance have a few interesting and rare characteristics. They alternate between schooling and foraging in the upper water column and extended periods of being almost completely buried in sand. For that, they rely on sand of a particular grain size and with very little organic content. It’s the kind of sand that defines large areas of the Stellwagen Bank.

Surprisingly little is known about the ecology and ecosystem importance of this sand lance species, although research on its European relatives (A. tobianus, A. marinus) is more advanced. In particular, experiments on early life stages of Northern sand lance have been lacking, save for some pioneering work on rearing methods of the related A. americanus (Smigielski et al. 1984). One question that was of particular interest to our lab involved the potential sensitivity of this fish species to carbon dioxide (CO2). That’s due to two other interesting and rare characteristics of sand lance. They spawn in late fall and winter in cold (and still cooling) waters, which is why their eggs and larvae develop extremely slow compared to other, more typical spring and summer spawning species. In addition, the species is found not in nearshore, but offshore coastal waters, where smaller seasonal and daily CO2 fluctuations more closely resemble oceanic conditions. Could sand lance offspring be particularly sensitive to higher levels of oceanic carbon dioxide predicted during the next 100 to 300 years as climate change effects intensify?

Sand lance caught on Stellwagen Bank in November 2014
Adult sand lance, shown here, is the favorite food for whales, seals, tuna and seabirds. Photo: Hannes Baumann
Early results suggest that sand lance larva, shown in closeup, are particulary sensitive to higher levels of carbon dioxide. Photo courtesy of Hannes Baumann

Over the past two years (2016-17), we successfully found and sampled spawning ripe sand lance on Stellwagen Bank during a narrow window in late November. Eggs and sperm from adults were removed on board or after being transported live to our laboratory at UConn Avery Point. We reared newly fertilized embryos to hatch and to the feeding larval stage, under different sets of temperature and CO2 conditions, measuring survival and growth traits along the way.

Our experiments are still ongoing, and rearing protocols are being improved.

The preliminary findings, however, are stunning. Survival to hatch was dramatically reduced under elevated and high compared to baseline CO2 conditions. It was severely lowered at higher (10°C or 50°F) compared to lower temperatures (5°C or 41°F). Our second experiment this year appears to repeat this pattern. If these results continue, that would mean sand lance is one of the most CO2-sensitive species studied to date.

General interest in sand lance goes beyond its sensitivity to carbon dioxide. Given the species importance for the ecosystem and coastal economy, there are now increasing efforts to better understand sand lance feeding ecology, distribution and relationship to the rest of the food web. In this regard, funding of our project by the Northeast Sea Grant Consortium proved prescient and a seed for subsequent grants from MIT Sea Grant and the Bureau of Energy Management (BOEM) to continue the work. Surely, the groundswell of interest in sand lance is commensurate with its importance and will enable insights into better management strategies for sensitive ecosystems like those along the U.S. Atlantic coast.

This graphic shows survival to hatch rates of Northern sand lance embryos reared at three carbon dioxide levels and two temperatures. Graphic: Hannes Baumann

Collaborators on this project are: D. Wiley of the National Oceanic and Atmospheric Administration-Stellwagen Bank National Marine Sanctuary; P. Valentine of the U.S. Geological Survey; and S. Gallagher and J. Llopiz, both of the Woods Hole Oceanographic Institution.

[Lab news] Live, feeding sand lance larvae

17 January 2018. Since November 2017, we have ongoing experiments with offspring of Northern sand lance (Ammodytes dubius), a winter-spawning forage fish of ecological importance along the North-American Atlantic coast. The clip below shows larvae almost two months after fertilization, developing nicely in 5C water and feeding actively on live rotifers. The experiments, led by Chris Murray for his PhD research, study the CO2 sensitivity of this species in our factorial larval rearing system. To our knowledge, this is the first time that this particular species has been reared that far under experimental conditions. Have a look!

Feeding sand lance
Sand lance (Ammodytes dubius) larvae feeding in green water on rotifers

[Lab news] Jake graduates with his Master’s degree!


Mumford Cove Oct 9th 2015

15 December 2017. The whole Baumann lab joins in congratulating Jake on his successful graduation with his Master’s degree from UConn! Jake embodied the spirit of a great student and team member, one who did not only seek to get something from the place he spent two years of his life but also one who left a great deal for us to remember. A wizard behind the camera, Jake has continuously enriched our lab with pictures that truly stand out and for which we will always be grateful. Jake helped in every aspect of the lab, but was particularly active in maintaing our monitoring efforts in Mumford Cove. For that, too, we are very grateful.

For his Master’s thesis, Jake painstakingly took it upon himself to retrieve and digitize the 40+ year time series of environmental observations from Project Oceanology, an ocean literacy organization that has been taking middle and high school students out to sea for decades. For the first time, his work allowed a quantitative evaluation of these data and a glimpse into the decadal changes in abiotic and biotic conditions in nearshore waters of Eastern Long Island Sound.

His Masters Thesis
Analysis of a Newly Digitized Long-Term Dataset of Environmental Observations from Long Island Sound
is accessible via the OpenCommons Site of the UConn Library.

During his time at the Baumann lab, Jake also conducted an experiment on potential maternal effects and their influence on offspring CO2 sensitivity, which was recently published in the Journal of Experimental Marine Biology and Ecology

Below is one of Jake’s timeless pictures of schooling juvenile Atlantic silversides. Many more pictures can be admired in our Imagery section or on Jake’s own Photography website RedSkiesPhotography

On 12 September 2017, young-of-the-year Atlantic silversides (Menidia menidia) school in nearshore waters (Photo: Jacob Snyder, Bluff Point, CT)

[Lab news] Baumann lab participates in Avery Point Open House Event

15 October 2017: All members of the Baumann lab – Hannes, Emma, Chris, Julie and Jake had fun at an Open House event at the Avery Point Campus as part of the 50th Anniversary celebrations. The whole department participated with a flurry of educational activities and fun exhibitions.
Our lab manned a table outside the Rankin Lab, telling people about the nearshore fish community, the phenomenon of ocean acidification and the measurement of pH in water. Everybody chipped in, thanks!
Hannes also premiered reciting Dr. Seuss’ “The Lorax” in front of young and old in the AP auditorium.

Check out some of the fun around the “Ocean Acidification and our fish” table:

There are fish!
Jake and Emma assist a little scientist in measuring the pH in our two demonstration tanks

Atlantic silversides from Mumford Cove, CT, swimming in our tanks. After the end of the demonstration, we released back into the wild.
Prof. Rob Mason taking briefly over our display. Emerging topic apparently – Mercury and ocean acidification

Fascinating sea life …

What an incredible creature a sea star is!

Hannes recited “The Lorax” – Dr. Seuss classic, comic-poetic tale of greed and environmental destruction

Julie manning our Ocean acidification outreach table at the Rankin Lab on 15 Oct 2017

[Lab news] Measuring juvenile silversides. Live.

10 October 2017. Today, Chris, Emma, and Julie measured over 400 juvenile Atlantic silversides for their length and weight. This time, however, we did not euthanize the fish before, but successfully measured them while still alive, only a little drowsy from the mild anesthetic we administered before.

Click on the video below to have a look for yourself.
Congratulations all, for a job well done!

[New publication] Nearshore pH and DO fluctuations across 16 US estuaries!

October, 2nd, 2017: Happy to announce that Estuaries and Coasts just published (online) our article that looked at unifying principles of pH and DO fluctuations across many US nearshore habitats. The datasets belongs to the US Nearshore Estuaries Research Reserves System (NERRS) and is one of the most extensive monitoring datasets in coastal aquatic habitats. In this case, we used 15 years of continuous monitoring data (> 5 million data points) from 16 different reserves across the US Atlantic, Caribbean, Gulf of Mexico, and Pacific coasts and analyzed short- to long-term variability in pH and DO fluctuations. Among the highlights:

  • Our analyses confirmed that large, metabolically driven fluctuations of pH and DO are a unifying feature of nearshore habitats. Even more so, we were able to show that across habitats, one can predict mean pH or mean diel pH fluctuations simply based on salinity and oxygen levels/fluctuations. This provided strong empirical evidence that common metabolic principles drive diel to seasonal pH/DO variations within as well as across a diversity of estuarine environments.
  • As expected, there were no interannual, monotonic trends in nearshore pH conditions; instead interannual fluctuations were of similar magnitude than the pH decrease predicted for the average surface ocean over the next three centuries.
  • By correlating weekly anomalies of pH, oxygen, and temperature, we found strong empirical support for the notion that coastal acidification — in addition to being driven by eutrophication and atmospheric CO2 increases — is exacerbated simply by warming, likely via increasing community respiration.

Citation and link:
Baumann, H. and Smith, E. (2017) Quantifying metabolically-driven pH and oxygen fluctuations in US nearshore habitats at diel to interannual time-scales Estuaries & Coasts (published online 2 Oct 2017)

Among many other aspects, the paper analyzed interannual trends in temperature (red bars), dissolved oxygen (%, blue bars), and pH (green bars) at 16 US Nearshore Ecological Research Reserves (NERRS), shown as yearly anomalies derived from averaging monthly anomalies for each variable, site, and year. Black trend lines were derived by LOESS smoothing.

[Lab news] Baumann & Nye lab attend 41st Larval Fish Conference

From 11-16 July, Hannes, Chris, Jake (Baumann lab, UConn) and Teresa (Nye lab, Stony Brook) were presenting research from our common NSF project at the 41st Larval Fish Conference, organized by the Early Life History Section of the American Fisheries Society in Austin, TX.

Hannes Baumann

Holding the fort and maintaining experiments at Avery Point were James, Julie, and Elle. Thank you for helping out.


We gave four talks in two sessions:

  • Baumann H., Snyder, J.T., and Murray, C.S. 2017. Quantifying offspring CO2-sensitivity in a fish: a meta-analysis.
  • Snyder, J.T., Murray, C.S., and Baumann H. 2017.
    Potential for maternal effects on offspring CO2 sensitivity in a coastal marine fish
  • Murray, C.S., Snyder, J.T., and Baumann H. 2017. A multi-factorial evaluation of temperature-dependent CO2-effects in a coastal forage fish.
  • Schwemmer, T., Baumann H., and Nye, J. 2017.
    Physiological effects of increased temperature and carbon dioxide on Atlantic silverside early life stages

Here is how Jake rates his first international conference experience:

Austin Texas, July 2017. “Attending the Joint Meeting of Ichthyologists and Herpetologists was my first visit to Austin Texas and my first large-conference presentation. My presentation was part of the Larval Fish Conference, a sub-section of the larger meeting, and I quickly learned how welcoming the larval fish group of researchers, scientists, professionals, and students were. Having not been to a “destination” conference like this before, I had little expectations, but I had a lot of fun networking, discussing research, and socializing. I think the coolest non-conference related event was seeing the Mexican Free-Tailed bats that live in the Congress Street Bridge, as every night around sunset they leave to go feed. Seeing hundreds of thousands of bats stream out of the bridge was incredible, and something I’d highly recommend. The city of Austin was great, and I spent much of the first day (pre-conference) exploring the city in the scorching heat. Overall the Baumann Lab had an excellent time at the conference, and can’t wait for the next one!”

Jacob Snyder “Austin 2017” photoblog. RedSkiesPhotography

[Lab news] Group effort – starting new silverside experiments in June 2017

It’s the beginning of June, and in the Baumann lab that means: high time for experimental research on the Atlantic Silverside, the famous forage fish and important model species! This year, we have several major objectives; our NSF-sponsored research examines the sensitivity of offspring to the individual and combined effects of high CO2 and low oxygen (Chris Murray), while in collaboration with our colleagues from Cornell University we rear several families for genetic and transcriptomic studies. Elle Parks, our REU student just started her work on the effects of CO2 and temperature on the starvation resistance of silverside larvae. As always, the days when new experiments start are a group effort, where everybody including many volunteers help. Thanks to Peter Morenus (UConn) for the coming down for documenting the activities!

This story is also featured on UConn Today.

[Field work] To Georgia and back in 48h – a special road trip for science

By H.B.

Somewhere after Richmond, VA, the sun sets and traffic on the I-95 begins moving better. At long last. The four people in the burgundy Dogde Challenger have all already cycled through their driving shifts once and dare an impatient glance at the time left. Still more than 8 hours. More than 8 hours to reach this very special location at the Atlantic coast – Jekyll Island, Georgia. In the trunk of the car a jumble of coolers and a beach seine, buckets, air pumps, and hoses topped with the crumpled witnesses of roadside dining. This is no ordinary road trip.

We, that are Aryn and Nicholas from the Therkildsen lab of Conservation Genetics lab at Cornell University and James and Hannes from the Fish Ecology Lab here at UConn; we went on this road trip to catch live, spawning ripe Atlantic silversides from the southern edge of the species distribution. We then intended to bring these fish back to UConn alive, sample another population from the south shore of Long Island (Patchogue, NY) and produce genetic crosses of these populations.

The broad goal of our expanding collaborative efforts with our geneticist friends from Cornell is the creation of an annotated genome of this species, which will be an important milestone in deepening or understanding of the molecular and genetic responses of organisms to local selection regimes and marine climate change. Given the Atlantic silverside’s ecological importance as an abundant forage fish along the American east coast and it’s rich history as a model organism in evolutionary and ecological studies, the annotated genome is the next logical step.

Even at hindsight, the plan still seems a little insane. But it worked. We indeed managed to catch spawning silversides at the Georgia site and then transported them immediately back to our Rankin Lab, which involved another 17 hours of driving back. After securing samples from Patchogue, we indeed managed to cross single parents from each site to produce full-sib crosses that will later be used to produce what geneticist call a linkage map. Other across and within-population crosses will be used to study gene expression at two different temperatures or raise adults for producing an F2 generation.

The silverside larvae are currently well, feeding, and growing up nicely. We all cross fingers for this enterprise to end in good samples and a step forward for genetic studies on a marine fish.