The Ocean Deep: Starving Oarfish or Climate Change?

It’s common knowledge that Oarfish of the family Regalecidae are cool, but we still know very little about them (Bester, 2017). It’s also common knowledge at this point that anthropogenic (or man-made) greenhouse gasses may have some effect on climate (Crowley, 2002).  As a result, the political and scientific realms have been furiously looking for ways to decrease carbon dioxide (CO2) emissions for decades, and debates have raged. One proposed solution from around the turn of the century was simply to pump the extra CO2 into the deep ocean, where it could be safely stored in the water column until photosynthetic creatures could dispose of it, or at least where it would stay and not cause any more progression in climate change (Seibel and Walsh, 2002). This seems on the surface like a perfect solution: the ocean is enormous and could easily store anthropogenic CO2. However, after studies were conducted on the physiological effects on deep sea creatures, the method was ruled far too environmentally detrimental. So, what could be happening that outweighs the impacts of climate change, and what does it have to do with Oarfish?

Well, first it’s important to understand a few physiology concepts. First is Metabolism, or the process by which organisms use Oxygen (O2) and a carbon-based fuel source (usually derived from food) to create Adenosine Triphosphate (ATP), which is the chemical that powers most cells, and CO2. This process, like all chemical processes, is dependent on the concentrations of the reagents, temperature, and pH among others, and is critical to sustaining life (Randall et al., 2002).

Second is respiration: the exchange of gasses necessary for an organism to continue metabolic processes. The process relies on 3 basic things: a good surface area over which to conduct exchange, a higher environmental partial pressure of O2 (and lower partial pressure of CO2) than that of the circulatory fluid entering the exchange area, and the ability of the organism to move that O2 through its body. Aquatic organisms accomplish this with gills, which provide ample surface area in their folds for gas diffusion to occur, and often with blood just like ours that contains Hemoglobin, the chemical that turns blood red when exposed to air. It is also responsible for binding and transporting absorbed O2 through the body. Hemoglobin is extremely sensitive to pH, and its oxygen binding power is easily changed by fluctuating pH, although this is often very species specific (Randall et al., 2002).

So, if we were to pump CO2 into the deep ocean, what would occur? Well, with the CO2 levels higher outside the organisms than inside, diffusion of CO2 wouldn’t be able to occur as easily, which would lead to a build-up of CO2 in the organism’s circulatory system. This would increase the pH of the fluid in the system (because dissolving CO2 in a fluid renders that fluid more acidic, just like the difference between flat pop and fizzy pop), rending Hemoglobin unable to bind to O2 as effectively. Finally, the lack of O2 would then lead to a lack of ATP in the organism via an inability to metabolize foods, and a decrease in the organism’s ability to do much of anything, often including live. This is much more acutely visible in deep sea creatures as hundreds of years of evolution under low light conditions have led to much slower predator-prey interactions, which has also lead, in combination with lower temperatures, to lower metabolic rates and lessened abilities to deal with pH changes (Seibel and Walsh, 2002). As little as a 0.2 reduction in pH is often enough to wipe out 50% of the zooplankton species in an area, which can cause serious food-chain issues in the deep sea as zooplankton often compose the base of oceanic food chains (Seibel and Walsh, 2002). Causing food chain issues could lead to a loss of biodiversity (Dudgeon et al., 2006), and given we know so little about the deep ocean, this could cost us huge. As an example, the Oarfish family of fishes are zooplankton filter feeders (Bester, 2017). They and so many more could be lost if we were to sequester CO2 at the bottom of the sea.

In conclusion, as tempting as it would be to just go ahead and save ourselves from climate change, we would do so at the cost of the biodiversity of the sea floor, and that’s simply not worth is as biodiversity is such an important factor of an ecosystem to preserve for economic, biomedical, and water quality reasons, among more (Dudgeon et al., 2006), and such actions would surely result in at the very least some loss of biodiversity (Seibel and Walsh, 2002). While it may yet be important to reduce climate change, certainly just pumping it to the bottom of the ocean isn’t the best way to solve that problem. After all, Oarfish need to eat too, and once again, your flappy friends thank you.



Bester, Cathleen (2017) Regalecus glesne. Florida Museum, University of Florida. Retrieved 04/18/2017 from:

Crowley TJ (2002) Causes of Climate Change Over the Past 1000 Years. Science 289(5477), 270. doi: 10.1126/science.289.5477.270

Dudgeon D, Arthington AH, Gessner MO, Kawabata ZI, Knowler DJ, Leveque C, Naiman RJ, Prieur-Richard RH, Soto D, Stiassny MLJ, Sullivan CA (2006) Freshwater Biodiversity: Importance, Threats, Status and Conservation Challenges. Biol Rev 81, 163-182.

Seibel BA, Walsh PJ (2002) Biological impacts of deep-sea carbon dioxide injection inferred from indices of physiological performance. J Exp Biol 206, 641-650. doi: 10.1242/jeb.00141

Randall JD, Burggren W, French K (2002) Eckert Animal Physiology. W. H. Freeman and Company, New York, pp 215–275.


Feature Photo: An illustration of an oarfish, which can grow up to 17 meters in length. Source: Catalina Island Marine Institute.

In-Text Photos: Beached oarfish from Isla San Fransico beach. Source: USA. Retrieved from:

Fiddler on the… Net?

Sharks, Skates, and Rays, collectively known a Chondrichthyans, are certainly in class of their own. As the predominant members of the class composed of cartilaginous fish (alongside the chimaeras), they are the stuff of nightmares and wonder, as evidenced by the famous cinematic classic: “Jaws”. But what if we could cause them just as much fear as they often cause us? What would that do to them?

As fishing pressures increase, more and more are caught in nets as by-catch, or accidentally caught organisms that fishermen don’t actively target (Smoker, 2000). For a fish, this can be scary, and cause a lot of stress which as we all know is bad for you in more ways than one. But what really is stress?

Stress is caused by an external stimulus, say a trawling net wrapping around you out of nowhere 100ft below the ocean, and your endocrine system reacting to it. Your endocrine system is the system of hormones your body utilizes to keep itself alive and functioning normally through changes. When the brain picks up on certain stimuli, it forces special organs in the body known as glands to secrete hormones that have effects on other organs. Effects can range from causing organs to secrete their own hormones in a process known as a hormone cascade, to causing the cells of a organ to increase metabolic or other specific functions (Randall et al., 2002). So when you eat a pie or are confronted by a bear (or a member of the opposite sex asking you to prom, often just as scary), your endocrine system causes a response to that.

The latter is the case with stress; when the brain is informed of a negative stimulus (like the aforementioned potential cutie asking you to dance out of nowhere) it sends signals to the hypothalamus (a gland in the center of the brain) to begin secreting hormones that affect the pituitary (another gland in the brain), which secretes hormones that affect the adrenal cortex (located right above your kidneys) that then secrete Cortisol, the stress hormone. This hormone then causes other organs, like the stomach, lungs, liver, adipose tissue (fat cells), immune system, and heart to go into overdrive and empower you to run as fast as you can from that potentially dangerous (or extremely awkward) situation (Randall et al., 2002).

Another aspect of running away from prom dates is the physical one: movement is hard and consumes energy. But all organisms have something called energy budgets; just as you have to draw from a bank account to buy things you need, so do animals, but with energy. The total energy available in an organism divided into the number of actions an animal takes to be successful is the energy budget, and going over budget in one category means detracting from another (Randall et al., 2002).

So what does this have to do with Chondrichthyans? They don’t have prom dates or banks, right? Sure, but they do have an endocrine system and an energy budget, and presumably an innate fear of trawl nets. One recently released study showed that pregnant Southern Fiddler Rays (Trygonorrhina dumerilii) subjected to simulated trawl net capture for 30 minutes in a lab during the pregnancy had pups that were on average 5-3mm shorter and 20-32g smaller than mothers that weren’t subjected to capture-like conditions. Further, the immune response in the mothers rose drastically for a short period after capture-simulation, and stayed higher for the duration of the pregnancy (Guida et al., 2017). This shows that when they were stressed the rays offset their delicate energy budgets for fetal development by consuming too much energy trying to escape the nets, and weren’t as able to give their pups the time they needed to develop. This could have ecological effects for the species as fishing pressures continue to be a threat (Guida et al., 2017; Smoker, 2000).

It’s not all bad news for the rays though. With the continuing research of agencies like the National Oceanic and Atmospheric Administration or NOAA, we’re learning more about where these Chondrichthyans have their pups, and helping fisherman to avoid areas where they could potentially create extra by-catch of these majestic creatures (Smoker, 2000). Remember to always do your part by eating sustainable seafood!

For more information on eating sustainably, check out the National Resources Defense Council’s “Smart Seafood Buying Guide” at

Not only do they have some great resources on sustainable seafood, but excellent tips on how to stay healthy eating it! Check it out, and remember: your flappy ray-friends thank you.



Guida L, Awruch C, Walker TI, Reina RD (2017) Prenatal stress from trawl capture affects mothers and neonates: a case study using the southern fiddler ray (Trygonorrhina dumerilii). Scientific Reports 7, 46300. doi: 10.1038/srep46300.

Smoker J (2000) Tools For Reducing Inadvertant Take and Bycatch Wastage of Skates and Sharks in Alaskan Hook-and-Line Fisheries. NOAA Fisheries, retrieved 04/13/2017 from:

Randall JD, Burggren W, French K (2002) Eckert Animal Physiology. W. H. Freeman and Company, New York, pp 215–275.

Photo Credits:

Featured Photo: Southern Fiddler ray. Source:Anthony Pearson. Some Rights Reserved.

In text Photo: A Southern Fiddler Ray (Trygonorrhina dumerilii) at the Melbourne Zoo. Source: SuperJew. Creative Commons Attribution-share Alike 4.o International.