Ocean Acidification

[Publication] Brachiopods thicken shells to compensate for shell dissolution under future OA conditions

15 April 2019. Today, Emma is happy to report that Environmental Science & Technology have just published the latest paper from her PhD about brachiopod resilience to future ocean acidification. This project involved long-term culturing of a polar and a temperate brachiopod under future ocean acidification and warming conditions. Substantial shell dissolution posed a threat to both species under ocean acidification, with more extensive dissolution occurring in the polar species.

Unexpectedly, we discovered that brachiopods thicken their shell from the inner shell surface when extensive dissolution occurs at the outer shell surface under ocean acidification. This is an important finding to further our understanding of how predicted vulnerable marine calcifiers might cope under future environmental change.


Cross, E. L., Harper, E. M. and Peck, L. S. 2019. Thicker shells compensate extensive dissolution in brachiopods under future ocean acidification. Environmental Science & Technology (published online March 29, 2019).

[Publication] Perspective on experimental OA research published!

15 April 2019. Today, the Canadian Journal of Zoology published a perspective on the progress and challenges of experimental ocean acidification research, written by Hannes last year as an extension of keynote lectures on this topic given at the Annual meeting of the Canadian Zoological Society (St. John’s, NL, Canada) and the Gordon Research Symposium (Waterville Valley, NH). The perspective takes stock of the progress achieved in the field over past two decades in four key areas, hoping to inspire particularly new researchers to the field to build on this foundation.

Abstract: Experimental studies assessing the potential impacts of ocean acidification on marine organisms have rapidly expanded and produced a wealth of empirical data over the past decade. This perspective examines four key areas of transfor- mative developments in experimental approaches: (1) methodological advances; (2) advances in elucidating physiological and molecular mechanisms behind observed CO2 effects; (3) recognition of short-term CO2 variability as a likely modifier of species sensitivities (Ocean Variability Hypothesis); and (4) consensus on the multistressor nature of marine climate change where effect interactions are still challenging to anticipate. No single experiment allows predicting the fate of future populations. But sustaining the accumulation of empirical evidence is critical for more robust estimates of species reaction norms and thus for enabling better modeling approaches. Moreover, advanced experimental approaches are needed to address knowledge gaps including changes in species interactions and intraspecific variability in sensitivity and its importance for the adaptation potential of marine organisms to a high CO2 world.
Illustration of the Ocean Variability Hypothesis positing that the CO2 sensitivity of marine organisms is related to the magnitude of short-term CO2 fluctuations in their habitat (e.g., from nearshore to open ocean) and length of their early life stage durations. It suggests that the most CO2 tolerant marine organisms are those that develop fast and (or) in habitats with large contemporary CO2 fluctuations, whereas the potentially most vulnerable species are those that develop slowly in relatively stable open-ocean habitats.

[Lab news] Chris defends his dissertation!

Chris smiling after his committee congratulated him on his dissertation defense (f.l.t.r: Chris Chamber, Chris Gobler (via Skype), Eric Schultz, Hans Dam, Chris Murray)
6 December 2018. Today, the whole Baumann lab is congratulating Chris Murray today on his great day of defending his PhD. Chris presented the essence of his research on climate change effects on coastal marine fish to a packed audience in the seminar room, fielded an array of questions, and showed his deep knowledge of the subject during the subsequent discussion with his committee.
Well done, Dr. Murray! We are all so very proud of you!

The bubbly is opened in the Rankin Lab in true experimenter fashion!
Chris Murray and Chris Chambers in front of the sand lance tank in the Rankin Lab

[Publication] Meta-analysis of silverside CO2 experiments published!

28 November 2018. Hannes, Emma, and Chris are happy to announce that Biology Letters just published our latest study, a meta-analysis of 20 standard CO2 exposure experiments conducted on Atlantic silverside offspring between 2012-2017. All these years of sustained experimental work resulted in the most robustly constrained estimates of overall CO2 effect sizes for a marine organism to date.
The study demonstrated:

  • A general tolerance of Atlantic silverside early life stages to pCO2 levels of ~2,000 µatm
  • A significant overall CO2 induced reduction of embryo and overall survival by -9% and -13%, respectively
  • The seasonal change in early life CO2 sensitivity in this species
  • The value of serial experimentation to detect and robustly estimate CO2 effects in marine organisms

Baumann, H., Cross, E.L., and Murray, C.S. Robust quantification of fish early life CO2 sensitivities via serial experimentation. Biology Letters 14:20180408

This figure shows the summary of early life responses to high CO2 conditions in Atlantic silversides across all experiments conducted between 2012-2017. Effect size was estimated using the log-transformed response ratio (A-D). Error bars are 95% confidence intervals. The responses are considered significant if the confidence interval does not include zero. Panels E-F: seasonal decomposition of response ratios, showing that silverside early life stages are most sensitive to high CO2 at the beginning and end of their spawning season.

[New publication] Complex CO2 x temperature effects in Menidia offspring

20 July 2018. We are happy to announce that Diversity just published Chris Murray’s paper on complex CO2 x temperature effects in Atlantic silverside offspring. The paper synthesizes 5 large multistressor experiments conducted since 2014, finding evidence for the large CO2 tolerance in this species across a large temperature range.

Congrats, Chris, to the second chapter published!

  • Murray, C.S. and Baumann, H. You better repeat it: complex temperature × CO2 effects in Atlantic silverside offspring revealed by serial experimentation. Diversity 10:69

  • MurrayBaumann-Fig1
    M. menidia. Offspring responses to control (blue), high (red), and extreme (green) CO2 conditions at four temperatures across five CO2 × temperature factorial experiments. Traits include embryo survival (A–E), hatch length (F–I), larval survival (J–N) and larval growth rate (O–R). Individual replicates are represented by small faded circles. Treatment means (±SD) are depicted by large, bold circles and connected by dotted lines. Note: different scales used for hatch length measurements due to differences in sample timing; panels F and G use 1dph length Y axis (left) while panels H and I use hatch length Y axis (right).

    [Lab news] Baumann and Dam labs at the Gordon Research Conference


    The beautiful venue of the Waterville Valley Hotel in New Hampshire

    Hannes introduced the Ocean Variability Hypothesis

    Phil Munday and Hannes chatting along the beautiful hike of Cascade Path
    19 July 2018. Members of the Baumann and Dam labs cherished the opportunity to participate in the Ocean Global Change Biology Gordon Research Conference in Waterville Valley, NH.

    The particularly intimate format of the Gordon Research Conference was wonderfully conducive to listening to groundbreaking science in form of keynote lectures and posters and to network with colleagues from all over the world. While Hannes gave a keynote lecture about experimental progress in assessing fish sensitivity to marine climate change, Chris, Emma, Jimmy and Hans presented their research all throughout the week during the poster sessions. The beautiful setting of the conference in New Hampshire’s White Mountains and the relaxed atmosphere were all contributing to one of the most unique conference experiences all year.

    Talks and posters presented:

    • Baumann H. Using experiments to assess the sensitivity of fish to marine climate change: progress and knowledge gaps. Invited keynote talk.
    • Murray, C.S., Wiley, D., and Baumann H. Sand lance offspring (Ammodytes dubius) show high sensitivity to combined climate stressors. Poster.
    • Cross, E.L., Peck, L., and Harper, E. Brachiopod resilience: thicker shells offset dissolution under future ocean acidification and warming. Poster.
    • Dam, H.G., DeMayo, J.A., Park, G., He, X., Finiguerra, M., Baumann H., and Pespeni, M. Rapid adaptation of a marine copepod to a greenhouse world. Poster.
    • DeMayo, J.A., Park, G., Norton, L., Finiguerra, M., Baumann H., and Dam, H.G. Costs of adaptation to a greenhouse world for the copepod, Acartia tonsa. Poster.


    The Baumann & Dam lab at the GRC hike


    [Lab news] Baumann lab attends the Larval Fish Conference in Victoria


    Holding the fort at the Rankin lab were Emma and Sydney, who did an excellent job. Thank you guys!

    The Delta Victoria Ocean Pointe Resort was the conference venue

    Before the conference, we all attended a workshop on larval fish identification

    Whale-watching with Corinne, Julie & Chris
    Here is how Julie experienced her first LFC:

    Ever since attending the American Fisheries Society conference in 2014, I’ve wanted to go to another fish-focused conference. I was lucky enough to attend the 42nd annual Larval Fish Conference this year in Victoria, British Columbia, and it surpassed all my expectations. The week started off with a larval fish identification workshop where we got to learn techniques from renowned larval fish experts (and see some really cool fish larvae!). The talks were impressive and thought-provoking, providing many new ideas for research and how to give an engaging talk. My favorite part was meeting all the larval fish ecologists whose publications I’ve been reading for my thesis. I spent most of my evenings exploring Victoria with other grad students attending the conference and left with many new friends from institutes all over the world! The trip ended with a whale watch, where we saw a pod of 5 Orcas. Overall, the Larval Fish Conference was a great experience that I hope to someday attend again!

    Oral presentations:

    • Pringle, J. and Baumann, H. Sex-specific growth and mortality patterns in juvenile Atlantic silversides (Menidia menidia) from Connecticut waters. Talk. 42nd Larval Fish Conference, Victoria, BC, Canada 24-28 June 2018
    • Murray, C.S., Wiley, D., and Baumann, H. Early life stages of the northern sand lance Ammodytes dubius show high sensitivity to acidification and warming in a CO2 × temperature factorial experiment. Talk. 42nd Larval Fish Conference, Victoria, BC, Canada 24-28 June 2018

    Water taxi in Victoria

    Old Victoria
    Beyond this point …
    Orca whale
    Harbor front with Parliament building
    Local celebrity, the one eyed seal

    [Lab news] Video of Mumford Cove probe swap

    14 June 2018. Members of the Baumann and Mason lab went on a trip to Mumford Cove, today, and Chris Tsang went along with his GoPro. Thanks to Charlie, the skipper, the ride was smooth and a pleasure, a swapping our pH, Temperature, oxygen, and salinity sensor was successfully swapped with a new one recording for the next weeks in 30 minute intervals. Wes Hoffman from the Mason lab, collected zooplankton with a Bongo-net. Sydney Stark, our NSF-REU student this summer, came along just for the fun.

    See the fun for yourself!

    [New publication] No CO2 effects on silverside starvation

    31 March 2018. We’re happy to announce that Marine Biology just published our latest study examining the starvation tolerance of silverside larvae and juveniles at contrasting CO2 conditions. We compiled observations from five separate experiments spanning different years, laboratories, temperatures, life stages, and CO2 levels. Contrary to expectation, we found that starvation rates were largely independent of the CO2 environment in this fish species.

    One major set of data was produced by Elle Parks as part of her Research Experience for Undergraduates (NSF-REU) in summer 2017. Well done, everybody!

    Hannes shows Elle Parks (REU 2017), how individual screen with enumerated embryos are suspended into the replicate rearing containers. (Photo: Peter Morenus, UConn)
    On 9 June, Elle and Julie strip-spawn Atlantic silverside females into spawning dishes covered in window screen for eggs to attach. (Photo: Peter Morenus, UConn)

    M. menidia. (A) Relative cumulative starvation mortalities of early juveniles reared under ambient (grey line, diamonds) vs. high CO2 conditions (black line, circles). Symbols depict individual replicates, lines represent treatment means. (B) Total length of juveniles perishing during the experiment at ambient (grey diamonds) vs. high CO2 conditions (black circles). Lines represent the median(solid lines), 5th and 95th percentiles (dashed lines) of TL estimated with locally weighted, non-parametric density estimators. The initial TL distribution at the beginning of the experiment is depicted on day 0 as the median (white circle), 5th/95th percentiles (whiskers) and the minimum and maximum (white stars).

    [New publication] Brachiopods resilient to global change

    Congratulations to Emma Cross to her new publication in Global Change Biology today!

    The common brachiopod Calloria inconspicua (pink shells) in their natural environment in New Zealand. Photo credit: Dr Liz Harper.
    Her study that was part of her PhD-research concludes that the brachiopod Calloria inconspicua, a common seafloor dwelling marine invertebrate from New Zealand, is more resilient to environmental change than expected.

    Read the full press release by the British Antarctic Survey