Lab News

Nature Climate Change publishes 25 generation copepod adaptation study!

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.

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Changes in egg production rate (EPR) and hatching success (HS) during the transgenerational experiment

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.

44th Larval Fish Conference held virtually 24-26 June

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.

The post-conference website is housed at https://lfc44.marinesciences.uconn.edu

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.


Our sandlance work featured in the CapeCodFishermen

Reposted from TheCapeCodFishermen, April 28th 2021

By David N. Wiley

Bluefin tuna and striped bass crash through the waves. Seabirds wheel overhead and plunge into the water. Gape-mouthed whales rise from below. Schools of cod and dogfish hide below the surface.

While the convergence of such diverse sea life might seem accidental, those in the know thank a small, slender fish called a sand eel for the bonanza.

Also known as sand lance, these three-to-six inch forage fish are a main food source for many of the top predators in the Gulf of Maine and on Georges Bank, including some of the most commercially important species.

As their name implies, sand lance are tied to sand habitat, but not just any sand will do. To avoid predators, sand lance spend most of the night and parts of the day buried. When disturbed, they rocket out of the bottom, then dive head first and at full speed back into the sand.

As a result, their sand of choice has to be coarse enough to hold oxygen for the fish to “breathe” while buried, but soft enough to allow high-speed body penetration. One of the reasons Cape Cod is their Mecca is a band of perfect sand stretching from Stellwagen Bank along the backside of Cape Cod, past Chatham and up through Georges Bank. Whether you are a fisherman, whale watcher or seabird enthusiast, it’s this band of sand, and the sand lance that inhabit it, that makes the Cape special.

Sand and sand lance are the backbone of Stellwagen Bank National Marine Sanctuary, responsible for it being one of the top places in the United States for viewing marine life, and a centuries old, highly productive fishing ground. Yet while fishermen appreciate the importance of sand lance, little is known about their biology and most of the world does not know they exist.

To remedy the situation, a team of researchers led by scientists from Stellwagen Bank National Marine Sanctuary with partners from Boston University, Center for Coastal Studies, University of Connecticut, U.S. Geological Survey and Woods Hole Oceanographic Institution have been studying the forage fish to determine its importance and unlock some of its secrets.

One of the project’s first goals was to identify the sand lance spawning season. Using a specially designed and permitted small-mesh trawl, fished from Steve Welch’s F/V Mystic or NOAA’s R/V Auk, the team captured and examined sand lance. Thought to spawn from late fall through winter, several years of work demonstrated that sand lance on Stellwagen Bank spawn in a very narrow window at the end of November. Eggs are deposited on the seafloor and hatch after approximately six weeks.

Then things get interesting. Once hatched, sand lance are tiny, free-floating larvae for two to three months. Given this long free-floating period and the currents flowing over Stellwagen Bank, many sand lance born on the bank cannot stay there. So where do they come from and where do their offspring go?

To answer this question, the team used hydrographic modeling to backtrack to where free floating particles (like larval sand lance) would have originated prior to their sand settlement in March or April, and where drifting particles would end up two or three months after hatching.

It appears that larval sand lance settling on Stellwagen originate off the coast of Maine; years of highest sand lance abundance correspond to conditions that would have transported additional larval sand lance from as far north as Nova Scotia. The same modeling indicated that larval sand lance originating on Stellwagen Bank transport south to the Great South Channel and Nantucket Shoals (but not Georges Bank). In some years, currents moved them as far as New Jersey.

This is just another example of the interconnected world that creates a productive marine environment. Since few sand lance in the study lived past three years, the dependence on shifting currents to populate the bank could be one thing responsible for boom and bust years typical of sand lance abundance. The team is currently examining genetics of sand lance taken from throughout the Gulf of Maine, the mid-Atlantic, and eastern Canada, to gain additional insight into population structure.

Do boom-bust years influence the distribution and abundance of predators? The team investigated the association of sand lance with humpback whales and great shearwater seabirds by placing satellite tags on both species to track their movements.

Throughout the Gulf of Maine, tracking revealed that both species spend the vast majority of their time over sand lance habitat, and DNA from fecal shearwater samples showed sand lance to be the bird’s main prey. Surveys in Stellwagen also demonstrated a high co-occurrence of sand lance, humpback whales and great shearwaters.

Sand lance feed primarily from February to July, mostly on Calanus finmarchicus copepods. They stop feeding from August through October, with low levels of feeding from the end of November to January. Body growth and fat content show similar trends, with length and fat stores increasing from February to July. After July, the fish retreat to bury in the sandy bottom, conserving energy for spawning.

The team then turned its attention to the future of the valuable fish, something of extreme importance to fishermen. Ripe fish captured in November were strip-spawned on board the boats and transported to Connecticut, where eggs and larvae were raised in special tanks that allowed temperature and acidity to be manipulated to mimic future ocean conditions under climate change. Increased temperature and acidity had a dramatic negative impact on larval survival. According to Dr. Hannes Baumann, whose lab led the work, sand lance may be unusually sensitive to ocean acidification.

The future of sand lance was also a focus of team members Joel Llopiz and Justin Suca from Woods Hole Oceanographic Institution. They came to some worrisome conclusions.

The abundance of tiny C. finmarchicus copepods directly influences sand lance health: Abundant C. finmarchicus led to good parental condition and high reproductive success, while low numbers resulted in poor parental condition and poor reproductive success. Scientists have suggested climate change scenarios in the Gulf of Maine will lead to reduced abundance of this critical copepod resource. Adding to the problem was their finding that warm slope water coming through the Northeast Channel north of Georges Bank led to the death of overwintering reproductive adults.

With the Gulf of Maine warming faster than 99 percent of the world’s oceans, there is concern about the future of sand lance and its potential impact to the productivity of the Gulf of Maine, Georges Bank and other areas. While states with fisheries and other marine resources supported by sand lance cannot solve climate change issues, they can work to make sand lance more resilient to climate change. One way is to eliminate as many non-climate stressors as possible.

For example, in 2020 Massachusetts promulgated a rule limiting daily sand lance landings to 200 pounds. Rhode Island followed suit in 2021. These rules were designed to discourage the development of a commercial fishery for the species, such as the huge industrial fishery in Europe’s North Sea.

Since a commercial sand lance fishery does not currently exist here, adopting this rule by other states would be an easy, proactive way to make our waters, and the people who depend on them, more resistant to climate change disruption.

(Dr. David N. Wiley is the Research Ecologist for Stellwagen Bank National Marine Santuary. Funding for the project was provided by the Bureau of Ocean Energy Management, The Volgenau Foundation, Northeast and Woods Hole Sea Grant, International Fund for Animal Welfare, Stellwagen Bank National Marine Sanctuary and the National Marine Sanctuary Foundation. Dan Blackwood, Dr. Gavin Fay, Peter Hong, Dr. Les Kaufmann, Kevin Powers, Dr. Jooke Robbins, Dr. Tammy Silva, Mike Thompson, and Dr. Page Valentine contributed to the study)

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‘Hooked on OA’ – Hannes talks about fish CO2 sensitivity to recreational anglers

25 February 2021. The Mid-Atlantic Ocean Acidification Network (MACAN) organized a four-part webinar series on Ocean Acidification geared specifically towards recreational anglers and shellfish collectors in the Mid-Atlantic region. The series is called “Hooked on OA” and invited Hannes on this February Thursday to explain the state of OA science particularly for fishes. A big thanks to the organizers and the more than 50 people who participated in this webinar.

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If you missed it and are still interested, you can watch the Zoom webinar here:

[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

Max-Zawell
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

JEB publishes paper on metabolic effects of high CO2 in silverside embryos! [New publication]

19 November 2020. We are happy to announce that the Journal of Experimental Biology just published the latest paper on CO2 effects in the early life stages of Atlantic silversides! For her PhD research at Stony Brook University, Teresa meticulously measured oxygen consumption in developing silverside embryos and newly hatched larvae exposed to contrasting oxygen and CO2 conditions throughout multiple experiments in 2017 and 2018. Her work shows that the metabolism of embryos but not larvae is sensitive to elevated CO2 conditions, leading to higher metabolic rates at normoxic levels, but reduced metabolic rates under low oxygen conditions, compared to controls. These basic empirical data confirm the emerging picture that CO2 effects in marine fish manifest largely if at all during early ontogeny, i.e., during the embryo stages. Well done, Teresa, and congratulations to your first lead-author paper!
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Conceptual diagram of the relationship between PO2 and RMR of M. menidia embryos in ambient and elevated PCO2. Hypothesized shifts in the relationship between embryonic RMR and PO2 are shown for elevated (orange) versus ambient (blue) PCO2. Our results (measured at the PO2 levels marked by black dots) suggest that PCO2 can influence both the critical oxygen partial pressure (Pcrit, gray lines) and the oxygen-independent RMR. At higher PO2 levels, RMR increases with PCO2, potentially owing to increased metabolic demand. As PO2 decreases, embryonic RMR reaches Pcrit and becomes oxygen dependent at a higher PO2 level in acidified than in ambient PCO2 conditions. Low intracellular red blood cell pH caused by high PCO2 can be expected to reduce hemoglobin–O2 affinity (Bohr effect) and make embryonic RMR less hypoxia resistant, which could manifest as an increase in Pcrit for embryos in elevated PCO2.

Welcome to Max Zavell & David Riser [Lab News]

Max-and-David
Max Zavell | David Riser

31 August 2020. The Baumann Lab is growing again and happy to welcome Max Zavell and David Riser as new graduate students to our lab!

Max Zavell just started on his journey as a PhD student in fall 2020, after graduating the same May with his Bachelor from the University of Rhode Island. Max is interested to work experimentally and continue exploring questions of coastal fish and climate change. In addition to continue working with Atlantic Silverside (Menidia menidia), his work will break new ground for our lab by starting with a new species for in our lab: Black Sea Bass (Centropristis striata). Growth and physiology of this northernmost grouper species is of interest, given its recent, explosive increase in abundance in Long Island Sound.

David Riser started his Masters in September 2020 after graduating with his Bachelor from the University of Connecticut and a Major in Marine Sciences. David already looks back on a successful career in the US Coast Guard, but now ventures to develop academic chops and expertise. In close collaboration with CTDEEP, he will analyze time series of Black Sea Bass catches in Long Island Sound and begin collecting and aging adult Black Sea Bass using otoliths.

Welcome from all of us!
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On 12 September 2017, a juvenile Black Sea Bass (Centropristis striata) sits in nearshore waters of Long Island Sound, while a school of Atlantic silverside juveniles passes by (Jacob Snyder, Bluff Point)

Baby sturgeon in the Connecticut River!

Babysturgeon

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)

[New publication] PLOS One publishes long-term silverside growth study!

27 July 2020. Big and proud congratulations to Chris Murray, who published his last big chunk of data from his PhD research on the effects of marine climate change on coastal marine fish. The publication in PLOS One synthesized 3 years of multiple, long-term experiments on Atlantic silversides (Menidia menidia) demonstrating consistent negative growth effects on high CO2 conditions. However, sometimes it takes more than just looking at means and standard deviations to elucidate these effects. Hence, in this paper, shift functions analyzing the different percentiles of distributions are employed.


Murray, C.S. and Baumann, H. (2020) Are long-term growth responses to elevated pCO2 sex-specific in fish? PLOS One 15:e0235817


The publication was featured in UConn Today “UConn Research: More Carbon in the Ocean Can Lead to Smaller Fish

By Elaina Hancock

As humans continue to send large quantities of carbon into the atmosphere, much of that carbon is absorbed by the ocean, and UConn researchers have found high CO2 concentrations in water can make fish grow smaller.

Researchers Christopher Murray PhD ’19, now at the University of Washington, and UConn Associate Professor of Marine Sciences Hannes Baumann have published their findings in the Public Library of Science (PLoS One).

“The ocean takes up quite a bit of CO2. Estimates are that it takes up about one-third to one-half of all CO2 emissions to date,” says Murray. “It does a fantastic job of buffering the atmosphere but the consequence is ocean acidification.”

Life relies on chemical reactions and even a slight change in pH can impede the normal physiological functions of some marine organisms; therefore, the ocean’s buffering effect may be good for land-dwellers, but not so good for ocean inhabitants.

Baumann explains that in the study of ocean acidification (or OA), researchers have tended to assume fish are too mobile and tolerant of heightened CO2 levels to be adversely impacted.

“Fish are really active, robust animals with fantastic acid/base regulatory capacity,” says Murray. “So when OA was emerging as a major ocean stressor, the assumption was that fish are going to be OK, [since] they are not like bivalves or sea urchins or some of the other animals showing early sensitivities.”

The research needed for drawing such conclusions requires long-term studies that measure potential differences between test conditions. With fish, this is no easy task, says Baumann, largely due to logistical difficulties in rearing fish in laboratory settings.

“For instance, many previous experiments may not have seen the adverse effects on fish growth, because they incidentally have given fish larvae too much food. This is often done to keep these fragile little larvae alive, but the problem is that fish may eat their way out of trouble — they overcompensate – so you come away from your experiment thinking that fish growth is no different under future ocean conditions,” says Baumann.

In other words, if fish are consuming more calories because their bodies are working harder to cope with stressors like high CO2 levels, a large food ration would mask any growth deficits.

Additionally, previous studies that concluded fish are not impacted by high CO2 levels involved long-lived species of commercial interest. Baumann and Murray overcame this hurdle by using a small, shorter-lived fish called the Atlantic silverside so they could study the fish across its life cycle. They conducted several independent experiments over the course of three years. The fish were reared under controlled conditions from the moment the eggs were fertilized until they were about 4 months old to see if there were cumulative effects of living in higher CO2 conditions.

Murray explains, “We tested two CO2 levels, present-day levels and the maximum level of CO2 we would see in the ocean in 300 years under a worst-case emissions scenario. The caveat to that is that silversides spawn and develop as larvae and early juveniles in coastal systems that are prone to biochemical swings in CO2 and therefore the fish are well-adapted to these swings.”

The maximum CO2 level applied in the experiments is one aspect that makes this research novel, says Murray,

“That is another important difference between our study and other studies that focus on long-term effects; almost all studies to date have used a lower CO2 level that corresponds with predictions for the global ocean at the end of this century, while we applied this maximum level. So it is not surprising that other studies that used longer-lived animals during relatively short durations have not really found any effects. We used levels that are relevant for the environment where our experimental species actually occurs.”

Baumann and Murray hypothesized that there would be small, yet cumulative, effects to measure. They also expected fish living in sub-ideal temperatures would experience more stress related to the high CO2 concentrations and that female fish would experience the greatest growth deficits.

The researchers also used the opportunity to study if there were sex-determination impacts on the population in the varying CO2 conditions. Sex-determination in Atlantic silversides depends on temperature, but the influence of seawater pH is unknown. In some freshwater fish, low pH conditions produce more males in the population. However, they did not find any evidence of the high CO2 levels impacting sex differentiation in the population. And the growth males and females appeared to be equally affected by high CO2.

“What we found is a pretty consistent response in that if you rear these fish under ideal conditions and feed them pretty controlled amounts of food, not over-feeding them, high CO2 conditions do reduce their growth in measurable amounts,” says Murray.

They found a growth deficit of between five and ten percent, which Murray says amounts to only a few millimeters overall, but the results are consistent. The fish living at less ideal temperatures and more CO2 experienced greater reductions in growth.

Murray concludes that by addressing potential shortcomings of previous studies, the data are clear: “Previous studies have probably underestimated the effects on fish growth. What our paper is demonstrating is that indeed if you expose these fish to high CO2 for a significant part of their life cycle, there is a measurable reduction in their growth. This is the most important finding of the paper.”

This work was funded by the National Science Foundation grant number OCE #1536165. You can follow the researchers on Twitter @baumannlab1 and @CMurray187.

[Lab news] Hannes gets promoted to Associate Professor

29 April 2020. Despite the lockdown and the virus, this is a joyful day for the Baumann lab – an unassumingly delivered note from the Provost – and both the end of a chapter and the beginning of a new era of Life and Science.

I’m grateful to so many people who aided this path along the way. Zosia, the boys, family, friends, and the many scientific mentors along the way.

This is a truly good day, not belittling the crisis & death all around us.

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