Why Putting Shrimp on Treadmills is Good Science

Example for: What Does this Scientific Paper Mean for People?

It’s likely you’ve come to this post after seeing my related post, “What Does this Scientific Paper Mean for People?” If not, I recommend skimming it first, as it details the process I’m about to use to assess the merit of a pretty famous example of potentially wasteful science.

First, I’ll find a few pieces of journalism about the shrimp situation.

 

shrimpscreenshot
Screenshot from the video

The study originally came to media attention when a video was posted to Youtube from David Scholnick’s (one of the researchers) website. One of the early articles on the video and surrounding research was by Sara Goudarzi (it can be found on Live Science and NBC). It’s a short article, without much context. Most of the implications can be found in one paragraph at the bottom of the article.

 

“Shrimp dealing with an infection would be less active and might be limited in their ability to migrate, find food, and avoid being eaten, Scholnick said. “These studies will give us a better idea of how marine animals can perform in their native habitat when faced with increasing pathogens and immunological challenges.””

So here is a bigger biological context: disease can affect parts of the shrimp life cycle. But why should we care? And why is this relevant?

There is a later report by Mike Selizic on Today which makes much more of an effort to detail the broader implications of the study.

“Both climate change and the runoff from agriculture and human activities affect the composition of ocean water, which in turn can lead to higher levels of bacteria. If shrimp with bacterial infections have less endurance and strength, that affects their ability to survive.”

Now we know more about the relevance. Human activity may cause increased disease vectors in shrimp. But still, why should we care about shrimp survival?

“Now that Burnett and Scholnick have a handle on how disease affects shrimp, they’re applying treadmill research to other critters that most of us think about only when they show up on a menu.”

In this case, it’s obvious and assumed as obvious by the article: we eat shrimp! Therefore, we should understand how disease affects them and other creatures we eat.

 

shrimp trawler
Shrimp Trawler

 

My example is so far showing that you can’t just take one journalistic article as your entire reference for the relevance of a study. That is especially true in this case. Many later articles focused on this study as a waste of taxpayer dollars and fruitless government spending. In cases like this, where the journalism is obviously controversial or political, it’s time to look to the paper itself. I’ve selected one paper that was within the larger study the treadmill video was a part of and conducted by the same team of researchers (David Scholnick, Karen Burnett, and Louis Burnett): Impact of Exposure to Bacteria on Metabolism in the Penaeid Shrimp Litopenaeus vannamei.

First, I’ll examine the Introduction. This is a relatively short paper; the Intro jumps straight into a very specific line of research, discussing first the role of gills in the crustacean immune system (the gills may eject bacteria). Large levels of bacteria may also impede respiratory performance in crustaceans. One statement relates to a somewhat larger picture:

“…low levels of environmental oxygen can impair the rate at which bacteria are cleared from the hemolymph.”

Although the Intro doesn’t go into more detail than this. It concludes with the specific research question: the investigators want to test respiratory performance of shrimp that have been exposed to bacterial pathogens in water with normal and low levels of oxygen.

The Discussion may have some larger context as well. The researchers noticed a significant “metabolic depression” in the infected shrimp, at levels that surprised even them and are worth of further research based on discrepancies between their test and other related tests. The Discussion then reiterates how bacterial infection and low-oxygen environments may compound each other’s effects on shrimp respiration and metabolism, an observation supported by their experiment.

Based on levels of lactate produced by the infected shrimp (lactate being the byproduct of anaerobic respiration, which takes over when there isn’t enough oxygen to support the muscular system), the researchers estimated there to be a “29% reduction in overall metabolism” because of bacterial infection. This is a big number, but what does it mean?

The last statement in the paper is perhaps the broadest and most meaningful.

“Our results provide a plausible explanation for the increased susceptibility of crustaceans to infectious disease in hypoxic environments and lend support for further investigations to determine how reduced ATP production associated with exposure to bacteria may impact overall activity and performance.”

Crustaceans respond worse to infection in low-oxygen environments. Though it isn’t stated outright why we should care about their “activity and performance,” it seems fairly obvious that it is because crustaceans are important to human dietary intake. We eat shrimp in large quantities, so it matters how they perform as a species (as in, if they can survive easily).

However, there’s one statement that the researchers could’ve gone into more that would’ve related things to a bigger picture. They keep mentioning hypoxic environments, but why would this be timely? This will require some further investigation.

The paper is somewhat short, and shorter papers are often so either because of space requirements (they can’t afford to give a lot of words over to explaining background and context) or because the background and context are assumed based on the expected readers of the paper. In this case, I’d go with the latter, at least partially. As someone with a background in marine science, I can already tell you why considering hypoxic environments and their effects on food animals like shrimp is important and relevant.

To delve more into hypoxia, I followed some citations. Boyd and Burnett’s Reactive Oxygen Intermediate Production by Oyster Hemocytes Exposed to Hypoxia led to a few more papers on hypoxic environments in general which mentioned how they are often seasonal, can cover large areas, and can have large effects on organisms living there and are associated with mortality events.

algae
Algae blooms like this one can soak up oxygen

Simply googling hypoxia at this point would easily lead to a more obvious relevance to humans: our actions, specifically the overproduction of certain nutrients mostly due to agriculture and industry, are fueling algal blooms in estuaries and gulfs. When the algae die and start to decay, the process consumes oxygen in the water and leads to a hypoxic event. Therefore, we are directly causing a drastic change in certain environments—understanding that change on different levels is in our best interest.

 

More information can be found in the other methods I mentioned at the end of my original post. To expand our viewpoints, we can find opinion pieces about the study. Betsy Hammond wrote a piece for The Oregonian allowing David Scholnick, the researcher who originally posted the shrimp treadmill video, to defend his work. There is one paragraph which sums up the defense pretty well:

“His decision to put shrimp on treadmills was a very tiny part of a much larger study by two College of Charleston professors, looking at how shrimps’ immune systems react when ocean warming or pollution makes it hard for them to breathe. The National Science Foundation paid $426,000 for that study, which was designed to help promote food safety and the health of commercial shrimp fisheries.”

So there’s an obvious meaningfulness to the work. Scholnick even published his own post about the entire incident; it’s a good way to get everything from his viewpoint and really see how everything played out.

There’s one last avenue of investigation we can follow, here. The NSF grant information for the larger study that the paper and video were a part of is available to view online. The entire Abstract for the project is one long justification for its existence: detailing the rise of hypoxic conditions, commercially important crustacean populations that may live in vulnerable environments, and what environmental and physiological variables may react to low oxygen conditions. It is very clear that more research into specific, physiological-level effects are needed to understand effects on entire populations of crustaceans.

So what have we learned from all this?

First, sometimes it takes a lot of research to figure out the big picture context of a single scientific study.

Second, good journalism is important in relating between science and society when the links are not obvious or too broad in scope to be in the original paper.

Third, putting shrimp on a treadmill was worthy science.

 

To the reader: are there any scientific studies that you’ve had difficulty relating to larger contexts, or that you can see the relevance of but others seem not to be able to? Also, I can repeat this procedure for papers you give me if you want more examples! Feel free to make requests.

Tips: What Does this Scientific Paper Mean for People?

Shrimp on a treadmill? A few years ago, you may have noticed a small uproar develop over research involving placing shrimp on underwater treadmills. The largest outcry involved claims of wasteful government spending, resulting in scrutiny for many researchers and research grants. The NPR has a great report on the situation if you’re interested in reading more.

So if you heard about that or got caught up in it in some way, which side is to be believed? Were the shrimp-on-treadmill studies wasteful or worth it? Here I’ll offer up some tips on checking for yourself what scientific studies mean for people and the world.

As an example for readers, I’ll use one of the papers published by the researchers who did the treadmill-shrimp study so we can look together to see if something presented as ridiculous might have bigger implications for society. I’ll put my example in a separate post.

Start with what you encounter first: journalism. Most journalistic pieces on science will relate whatever research is being talked about to the world at large. A news piece will usually have interviews with the researchers involved and one or more researchers in the field who were not involved that will discuss impacts of the study. This can range from obvious things like new technology and health benefits to studies that will advance the field (testing new methods or techniques, for example).

Journalism should not be the last step if you have further questions, though—especially if the benefits or implications of a study still aren’t obvious outside of one specific field. You have to move on to the paper itself (the following tips all assume you can access the full paper—in some cases, you will not be able to).

The two most important sections of the paper to read for broader implications are the Introduction and Discussion (or Conclusions).

The Introduction will start with broad context, explaining what field is being studied, questions and progress within that field, and often the relation of that field of science to society. It will usually narrow down in scope until it addresses the specific research questions of the study. In longer papers, you’ll get a much longer, more involved background while in short ones it may feel rushed and not include as much context, but don’t worry about that for now.

The Discussion will talk about the findings of the paper and what they mean in the context of the field and for science. Usually, the Discussion will take an opposite, mirrored effect to the Intro: broadening in scope until it finally addresses larger societal implications.

Most of your questions, therefore, will probably be answered by the researchers themselves in the Intro and Discussion. But what if you still don’t feel like it has much impact on society? You may have to dig into the background research.

Start with the list of references at the end of the paper. Go through the Intro and Discussion again, and wherever you see a citation (usually an author’s name and date or sometimes just a number) for a piece of information that seems like it could be part of the big picture, find it in the list of references and try to find that paper. With some background (detailing why the field was explored in the first place) or side studies (which link the research to something more relevant to society), you should find broader implications very quickly.

Sometimes this process may result in detective work where you continually find new papers to skim to try and broaden your scope, but by this point, you may be wondering if that original paper really means that much if you have to get so far removed to see the impacts.

The answer to this musing, of course, is perhaps it doesn’t. If a paper doesn’t seem to advance a field (by clearing up a definition, testing new methodologies, or investigating important hypotheses), perhaps it’s not particularly important. But this will rarely be the case. It shouldn’t take too much searching to find links between the paper and important, relevant topics (important and relevant to some sector of society, anyway).

A lot of what we view as important science is very subjective. Take space exploration, for example. Many people see it as crucially important to the existence of humanity and imperative to fulfilling our species’ drive for discovery. However, some see it as a waste. This stance seems impossible to me, but the views of people are as varied and diverse as the people themselves.

If you can’t see why a paper is important, before disdaining it try to have an open mind. Perhaps there is a perspective from which a study or bit of research is very important. Perhaps for some people, it is life or death, or will affect their livelihoods, or will save endangered species (another occasionally divisive topic which for some people is extremely important and worthy). If you want to practice at this, try looking for opinion pieces about the scientific field or find the webpages of the scientists involved in the study to get a better feel for how it affects their lives. Expanding your horizons before casting doubt and shame is always the best option in my experience.

There is a side note to this process as well: funding. In the case of the shrimp-on-treadmills study, most of the outrage seemed to stem from the fact that there was government funding involved. When it is a case of whether public funds are being put to good use, try researching the funding agencies. The primary federal scientific funding agency is the National Science Foundation. The NSF receives thousands of project proposals every year, selecting only about a quarter of them to which to allot funding. It has strict merit review criteria as part of its reviewing process. Specifically, from Chapter 4, Section A of the Proposal and Award Policies and Procedures Guide:

“When evaluating NSF proposals, reviewers will be asked to consider what the proposers want to do, why they want to do it, how they plan to do it, how they will know if they succeed, and what benefits could accrue if the project is successful. These issues apply both to the technical aspects of the proposal and the way in which the project may make broader contributions. To that end, reviewers will be asked to evaluate all proposals against two criteria:

  • Intellectual Merit: The Intellectual Merit criterion encompasses the potential to advance knowledge; and
  • Broader Impacts: The Broader Impacts criterion encompasses the potential to benefit society and contribute to the achievement of specific, desired societal outcomes.

The following elements should be considered in the review for both criteria:

1. What is the potential for the proposed activity to:

a. Advance knowledge and understanding within its own field or across different fields (Intellectual Merit); and

b. Benefit society or advance desired societal outcomes (Broader Impacts)?

2. To what extent do the proposed activities suggest and explore creative, original, or potentially transformative concepts?”

The NSF already evaluates what it gives funding to based on broader impacts to society, so your tax dollars (at least on the federal level) are most likely not going to waste.

I hope my tips have helped you and will continue to help you in evaluations of the merit of research. It can be hard, at first, to see why a hyper-specific scientific study might be important—science is usually incremental and diverse. But if you really want to know, the answers are likely already there.

 

To the reader: do you have tips or advice of your own for assessing how important a given study is to society? Are there any fields of science you think are wasteful or not worth publicly funding? Or the reverse: any fields (or specific studies) usually seen as obscure and pointless that you can relate to a bigger scale?

Tips on Reading Scientific Papers

As a former science student, I’ve navigated the turbid sea that is the scientific literature. I’ve developed a few reading habits that may help you if you don’t have a science background. These are tips based on the assumption that you don’t have a lot of time to dedicate to understanding a paper and want to make the most of what you have.

 

how-to-read-a-sci-paper
Dr. Raff’s comprehensive guide to understanding scientific papers, from The Impact Blog

First, if you want a full, comprehensive understanding of the paper, I recommend this guide by Dr. Jennifer Raff. It’s great for anyone who wants or needs a thorough understanding of the science, such as journalists, industry professionals, or students. However, most people don’t have much time to spare on endeavors like this. Dr. Raff’s guide is a process that will take multiple hours, depending on the length and complexity of the paper. So what if you’re short on time but still want some understanding?

 

It’s likely that you found the paper through a news article. This is always a good starting point since it’s the journalist’s job to translate the material for general audiences. So start there. If you want to go deeper, here are a few additional tips based on the usual layout of a scientific paper:

Abstract: this is the condensed summary of the paper, so it seems like a good place to start, right? It can be, but be wary of stopping here. There isn’t much context or explanation, so you’ll probably have more questions than answers upon reading it. So continue immediately. The condensed wording might also mean extra technical jargon as well. I usually use Abstracts to figure out which papers I want to read (which are most useful to whatever question or interest I have at the moment).

Introduction: the beginning of the Intro will usually have the broad, background context for the research. What field is being studied? What is known or not known? It will generally narrow down until it identifies the specific research questions for this paper. The beginning and end of the Intro, therefore, are the most important parts to read, but the entire section and its context are all useful if you want to really understand this area of science in general. Make a note of unfamiliar terms and look them up if they seem important (sometimes there will be a side note or bit of background that isn’t necessary to understand for the paper in question; otherwise Google is your friend!).

Methods: usually placed after the Intro (or after a subsection identifying the research questions), but occasionally at the end of the paper. If you want a quick understanding of the science, it’s okay to just skim the Methods for an overview of the work. It’s important to take note of sample sizes, study locations, and get a general sense of the methodology (was there field research or lab research involved? If it’s medical, were the subjects human or animal?). If you don’t have a background in science, this section will usually be very jargon-heavy and difficult to parse, and if you don’t have much time it probably won’t be worth looking up everything you don’t know. I usually only spend a lot of time on Methods if they’re important to what I’m doing (designing experiments for my classes) or if I actually have questions on what the researchers did.

Results: again, if you don’t have a background in science, skimming this section is okay. Pay attention to figures and graphs, as they’ll usually summarize important parts of the data, and work hardest on understanding those; a good paper will have good figures. You may not have a background in statistics, but there are a few resources to help you out in general. The Science Writer’s Handbook has a great chapter on basic stats that are useful for understanding papers, and I’ll summarize a few important points: correlation does not imply causation, but it is suggestive of some relationship; pay attention to confidence intervals (large intervals or intervals that include zero may be a bad sign); know the difference between relative and absolute risk in medical studies, and look for p-values (a p-value of 0.05 or less is best: it means the results were significant and unlikely to have occurred by chance). “Significant” is the most important word to watch out for in statistics: it means that the relationship uncovered is more likely to be real and not just a chance occurrence.

This is a good introductory statistics tutorial for anyone interested in learning more.

Discussion/Conclusion: this section (or pair; occasionally you’ll see both) is very important for understanding both the scientific context and relevance of the paper. The researchers will interpret their results and relate them to broader contexts, so if you have trouble with the Results section, it’s okay to skip to the Discussion (as long as you’re not worried about researcher bias—I’ll have future tips posts on looking for bias in scientific papers). Often the researchers will also pose questions and future lines of research; these are important to pay attention to if you’re interested in the general field and want to keep up with it. However, if the interpretation of the results is what is most important to you, look for subheadings, subsections, or paragraphs on each result (if this was a multistep experiment with multiple results) and skim the big-picture explanations at the ends of these sections.

References: if any piece of background information raises questions for you or seems especially interesting, track down the citation (in the text of the paper, citations will usually be the name of an author and date of publication for a cited background paper or occasionally a number directing you to a specific entry in the References). Looking up these papers for additional information if you have time will give you a bigger sense of where the study fits in the field and also additional science knowledge (always a good thing!). A note: expect some papers to be behind paywalls: then you will likely only have access to the Abstracts.

General Tips: Printing out the paper in question and marking notes on it is probably the best way I’ve found for organizing and keeping track of my thoughts.

These have been my tips for understanding a scientific paper. It’s essentially the procedure I used in college when I didn’t need a full understanding of a paper and what I still do when I’m a little extra curious about a news article.

To readers: do you have additional tips or resources of your own?