Media

[Lab news] Adult black sea bass arrive at UConn’s Rankin lab

Establishing a Black Sea Bass brood stock to study early life history effects of warming and acidification

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Max Zavell

December 2020. We are happy to announce that as of a few weeks, we are now housing two brood stock populations of Black Sea Bass (Centropristis striata) at UConn's Department of Marine Sciences Rankin Seawater Lab. The adults will be reared for the next few months under contrasting CO2 regimes in 1000gal tanks each. After photoperiod manipulation and hormone-injection we plan to strip-spawn adult fish and test their offspring for their CO2 and temperature sensitivity. Black Sea Bass are rapidly increasing in abundance in New England Water and the Gulf of Maine, but research on early life stages is still lacking. PhD student Max Zavell meticulously taking care of these fish now.

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Catch a glimpse of these beautiful animals below

Baby sturgeon in the Connecticut River!

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Juvenile Atlantic sturgeon caught in June 2020 in the Connecticut River (photo: Jacque Benway, CTDEEP)

By Kelli Mosca.
3 July 2020. Atlantic sturgeon (Acipenser oxyrinchus) is an endangered, long-lived, anadromous fish that is found along the North American coast from the St. Lawrence River (Canada) to the St. John’s River (Florida). Historically, Atlantic sturgeon spawned in the Connecticut River, but until recently spawning populations were thought to be extirpated. In June 2020, a small, very young and therefore likely pre-migratory specimen (253mm) was captured by CTDEEP in the Connecticut River (above). This discovery is only the second after the first occurrence of small sturgeon in 2014! Together, this may be the beginning of a small Atlantic Sturgeon population rediscovering their long-lost spawning ground in the Connecticut River. CTDEEP and the Baumann Lab are working to find more fish of this size- and year class, and answer related questions about surgeon age and size and migration patterns. (CT SeaGrant project)

[Lab news] Hannes & colleagues organize a Virtual Town Hall

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23 June 2020. It’s been a remarkable day. A remarkable few months of preparation. But on this Tuesday in June, more than 250 people from all over the world logged in to a UConn WebEx Event organized by Hannes Baumann, Eric Schultz, Jacqueline Webb, Paul Anderson and Jon Hare. The event, billed as the “1st Virtual Larval Fish Science Town Hall” was of course a product of the strange and challenging times we live in right now. A consequence of almost a year of painstaking preparations for the 44th Larval Fish Conference in Mystic, CT … eclipsed by the COVID-19 pandemic that made having a physical science conference impossible.


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Number of attendees per minute throughout the day. Science sessions were followed by 120-170 attendees worldwide.
Network Mentors

The Virtual Town Hall gave 16 speakers from around the world the opportunity to communicate their science, while providing a forum for the community to interact. The Early Career Committee of the AFS Early Life History Section contributed as well, organizing a round table discussion led by Kelsey Swieca with Chris Chambers, Jackie Webb, and Peter Konstantidinis. Individual networking meetings – although hobbled initially by technology – were held after the meeting between senior and early career researchers.

And best of all – more than 40 people participated in a picture contest, contributing stunning images of larval fish or larval fish science.

For more information, speaker bios’s, talk titles, abstracts and even some video please visit the event website lfc44.uconn.edu


Some of our personal favorites among the best larval fish picture submissions

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Mike Bartick | Ribbon fish
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Irene Middleton | A diver checks out a juvenile flying fish at the Poor Knights Islands in New Zealand
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Suzan Meldonian | Cyclopsetta fimbriata, photographed in situ along Gulf Stream Current, SE Florida
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Winner – Kerryn Parkinson | Mola sp – a larval sunfish collected off New South Wales, Australia.
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Gabriel Monteiro | Caulolatilus chrysops larvae cleared and stained. This specimen belongs to ColBIO USP biological collection.
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Harvey Walsh | Bothus larvae sorted at sea from a bongo net tow collected during the summer of 2017 aboard the NOAA Ship Gordon Gunter.
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Chris Murray | Wild Pacific herring spawn from Skagit Bay, WA (~72 h old). Note the flat edge of the egg where it was adhered to sea grass.
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Henrique Grande | Post-larval reef fish Acanthurus coeruleus Bloch & Schneider, 1801 collected in 2015 using light traps in the Bay of Tamandaré, Brazil.

[New Publication] IUCN published ocean deoxygenation report!

9 December 2019. During the COP25 summit in Madrid, the International Union for Conservation of Nature (IUCN) released its latest comprehensive report titled “Ocean deoxygenation: everyone’s problem” that compiles the current evidence for the ongoing, man-made decline in the oceans oxygen levels. The 588 page, 11 chapter wake-up call to these detrimental changes was produced by leading experts in the field. We are happy to announce that Hannes is one of the many authors of this document, co-authoring chapter 6 “Multiple stressors – forces that combine to worsen deoxygenation and its effects“.

From the executive summary:

“The equilibrium state of the ocean-atmosphere system has been perturbed these last few decades with the ocean becoming a source of oxygen for the atmosphere even though its oxygen inventory is only ~0.6% of that of the atmosphere. Different analyses conclude that the global ocean oxygen content has decreased by 1-2% since the middle of the 20th century. Global warming is expected to have contributed to this decrease, directly because the solubility of oxygen in warmer waters decreases, and indirectly through changes in the physical and biogeochemical dynamics.”

From the summary of chapter 6:

  • Human activities have altered not only the oxygen content of the coastal and open ocean, but also a variety of other physical, chemical and biological conditions that can have negative effects on physiological and ecological processes. As a result, marine systems are under intense and increasing pressure from multiple stressors.
  • The combined effects of ‘stressors’ can be greater than, less than, or different from the sum of each stressor alone, and there are large uncertainties surrounding their combined effects.
  • Warming, acidification, disease, and fisheries mortality are important common stressors that can have negative effects in combination with low oxygen.
  • Warming, deoxygenation, and acidification commonly co-occur because they share common causes. Increasing carbon dioxide (CO2) emissions simultaneously warm, deoxygenate, and acidify marine systems, and nutrient pollution increases the severity of deoxygenation and acidification.
  • A better understanding of the effects of multiple stressors on ocean ecosystems should improve the development of effective strategies to reduce the problem of deoxygenation and aid in identifying adaptive strategies to protect species and processes threatened by oxygen decline.
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Chapter-6


Access the full report from IUCN.org

[Presentation] Callie presents research at the Graduate Climate Conference

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Callie presenting her poster to other graduate students
November 8, 2019. Callie Concannon joined other graduate students of the Department of Marine Sciences to present her thesis research at the Graduate Climate Conference in Woods Hole, MA. She presented a poster entitled “Long-term CO2 and temperature effects on fecundity and oocyte recruitment in the Atlantic silverside
Her preliminary findings can be summarized as:

Warmer, more acidic environments impact reproductive output in the Atlantic silverside


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The participants of the Graduate Climate Change conference in November 2019

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[New publication] Science publishes our silverside genetic study!

Fishing changes silverside genes
1 August 2019. We are overjoyed that our paper on genetic changes in experimental silverside populations subjected to strong size-selective fishing has just been published by Science!


Therkildsen, N.O., Wilder, A.P., Conover, D.O., Munch, S.B., Baumann, H., and Palumbi, S.R. (2019)
Contrasting genomic shifts underlie parallel phenotypic evolution in response to fishing
Science 365:487-490
Related perspective: Fishing for answers Science 365: 443-444 | Cornell Press release | UConn Press release


Over recent decades, many commercially harvested fish have grown slower and matured earlier, which can translate into lower yields. Scientists have long suspected that rapid evolutionary change in fish caused by intense harvest pressure is the culprit.

Now, for the first time, researchers have unraveled genome-wide changes that prompted by fisheries – changes that previously had been invisible, according to a study published in Science by a team of researchers including Hannes Baumann, UConn assistant professor of Marine Sciences, who collaborated with researchers at Cornell University, the University of Oregon, the National Marine Fisheries Service, and Stanford University.

In unprecedented detail, the study shows sweeping genetic changes and how quickly those changes occur in fish populations extensively harvested by humans, says Baumann.

“Most people think of evolution as a very slow process that unfolds over millennial time scales, but evolution can, in fact, happen very quickly,” said lead author Nina Overgaard Therkildsen, Cornell assistant professor of conservation genomics in the Department of Natural Resources.

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Observed shifts in adult size. Trends across generations in mean length at harvest (standardized as the difference from the mean of the control populations in each generation) ± the standard deviations in up-selected (blue shades), down-selected (yellow and orange shades), and control populations (green shades).

The all-pervasive human meddling in our planet’s affairs undeniably reached the genetic make-up of its organisms.
— Hannes Baumann, UConn.

In heavily exploited fish stocks, fishing almost always targets the largest individuals. “Slower-growing fish will be smaller and escape the nets better, thereby having a higher chance of passing their genes on to the next generations. This way, fishing can cause rapid evolutionary change in growth rates and other traits,” said Therkildsen. “We see many indications of this effect in wild fish stocks, but no one has known what the underlying genetic changes were.”

Therkildsen and her colleagues took advantage of an influential experiment published back in 2002. Six populations of Atlantic silversides, a fish that grows no bigger than 6 inches in length, had been subjected to intense harvesting in the lab. In two populations, the largest individuals were removed; in another two populations, the smallest individuals were removed; and in the final two populations, the fishing was random with respect to size.

After only four generations, these different harvest regimes had led to evolution of an almost two-fold difference in adult size between the groups. Therkildsen and her team sequenced the full genome of almost 900 of these fish to examine the DNA-level changes responsible for these striking shifts.

The team identified hundreds of different genes across the genome that changed consistently between populations selected for fast and slow growth. They also observed large linked-blocks of genes that changed in concert, dramatically shifting the frequencies of hundreds of genes all at the same time.

Surprisingly, these large shifts only happened in some of the populations, according to the new paper. This means that there were multiple genomic solutions for the fish in this experiment to get either larger or smaller.

“Some of these changes are easier to reverse than others, so to predict the impacts of fisheries-induced evolution, it is not enough to track growth rates alone, we need to monitor changes at the genomic level,” said Therkildsen.

When the experiment was originally conducted nearly two decades ago by co-authors David Conover, professor of biology at the University of Oregon, and Stephan Munch of the National Marine Fisheries Service, the tools to study the genomic basis of the rapid fisheries-induced evolution they observed were not available. Fortunately, Conover and Munch had the foresight to store the samples in a freezer, making it possible to now return – armed with modern DNA sequencing tools – and reveal the underlying genomic shifts.

Research like this can assess human impacts, and improve humanity’s understanding of “the speed, consequences and reversibility of complex adaptations as we continue to sculpt the evolutionary trajectories of the species around us,” Therkildsen said.

“What’s most fascinating about this is that life can find different genetic ways to achieve the same result. In this study, two experimental populations evolved smaller body size in response to the selective removal of the largest fish, which is what most trawl fisheries do. However, only by looking at the genetic level we demonstrated that these two experimental populations evolved via two completely different genetic paths,” says Baumann.

The good news for the Atlantic silversides is that the fisheries selection was able to tap into the large reservoir of genetic variation that exists across the natural range of this species from Florida into Canada, said Therkildsen: “That genetic bank fueled rapid adaptation in the face of strong fishing pressure. Similar responses may occur in response to climate-induced shifts in other species with large genetic variability.”

“Scientists have coined the term Anthropocene in recognition of the all-pervasive human alteration of the earth’s climate, oceans, and land. No matter how ‘pristine’ a piece of nature may look to us at first glance, examine it thoroughly enough and you will find a trace of human in it. Take a cup of water from the middle of Pacific Ocean and a handful of sand from a ‘pristine’ beach – and you will find little plastic particles under the microscope,” says Baumann. “The parallel to this study is that the all-pervasive human meddling in our planet’s affairs now undeniably reached the genetic make-up of its organisms. Today’s fishes may superficially look the same as always, but their genes are not. They bear witness to human alteration.”

In addition to Baumann, Therkildsen, Conover, and Munch, co-authors included former Cornell postdoctoral researcher Aryn P. Wilder, now a researcher at San Diego Zoo Institute for Conservation Research; and Stephen R. Palumbi, Stanford University.

This work was funded by the National Science Foundation.

[Lab news] Hannes, Chris and Emma at the 43rd Larval Fish Conference!

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Chris, Hannes, and Emma

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Beautiful view from Mallorca’s most northern point, Cap Formentor

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Peter Gronkjaer, Dominique Robert, Arild Folkvord, Hannes during the conference tour
25 May 2019. Hannes, Chris and Emma attended this years 43rd Annual Larval Fish Conference in Palma de Mallorca, Spain. The event was hosted by IMEDEA’s Ignacio Catalan and colleagues and was attended by more than 140 participants. As usual, the small but international make-up of the meeting and made it into a memorable event of science, networking and seed for potential future collaborations. While Chris reported on our past experiments on factorial CO2 by O2 effects on Atlantic silverside early life stages, Emma presented the latest findings on our silverside experiments using computer-controlled CO2 and O2 co-fluctuations.

Before and after the conference, there was also some time to explore the beautiful island of Mallorca with its breathtaking mountain scenery and turquoise coves.


Chris and Emma’s presented:

  • Murray, C.S., Cross, E.L., and Baumann H. A factorial evaluation of the combined effects of acidification and hypoxia in Atlantic silverside offspring. Talk.
  • Cross, E.L., Murray, C.S. and Baumann H.Diel and tidal cycles of CO2 and dissolved oxygen conditions provide physiological refuge to a coastal forage fish, Menidia menidia under acidification and hypoxia. Talk.

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A special thanks to Lucas and Callie for holding the fort at home!

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Cala des Moro

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Martha Moyano and Hannes
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Valdemossa

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Cap Formentor

[Lab news] Whole life cycle CO2 fish are getting sampled

18 April 2019. This Thursday was a long day in the Baumann lab, because we sampled and processed over 200 adult silversides from a unique experiment. These fish were fertilized in the lab and reared from eggs to adulthood under different temperatures and contrasting CO2 conditions. We are interested to see, if future ocean conditions have measurable effects on this species fecundity, growth, and oocyte characteristics. We also took tissue and genetic samples, with an effective line-up of hands, i.e., Hannes, Emma, Chris, Callie and Lucas.
Good teamwork all!


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[Media] WSHU public radio covers Project Oceanology story

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4 April 2019. Following the publication of our study on the Project Oceanology time-series in Marine Environmental Research and the subsequent article about it in TheConversation, today the story was featured by WSHU public radio, in Ron Ropiak’s show “The Full Story“.

Have a listen, how Hannes describes both the findings and the significance of the Project Oceanology time series.


Listen

[Research news] Live staining of silverside neuromasts at URI

By Emma Cross.

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23 Juli 2018. Yesterday Hannes and Emma took a short road trip to the University of Rhode Island to visit Professor Jacqueline Webb’s lab to learn about in vivo fluorescent imaging.

This technique involves placing live fish in a fluorescent mitrochondrial stain for 5 minutes before imaging different areas of the fish under a dissecting microscope equipped with an epiflourescence light source. This allowed us to visualize small sense organs called neuromasts located in tubular canals in the head, trunk and tail, which form the fish sensory lateral line system used to detect water flows.


We are interested to see if high CO2 conditions affect these neuromasts in the Atlantic silverside, which could impact their critical schooling behaviors.

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Take a look at some of the stunning images below! Thank you to Jackie and all the lab for a fun-filled day!

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