Fracking, also known as hydraulic fracturing, is the cracking and opening of rocks by water, sand and chemicals in the Earth's depths to extract natural gas and oil trapped in reservoirs such as limestone, shale and sandstone. While hydraulic fracturing can boost the economy by extracting "tight oil" or "tight gas" which would otherwise be unreachable, lots of controversy has ignited, especially on the environmental front. According to the United States Environmental Protection Agency, cited by the NRDC, from 2006 to 2012 there have been 151 reported spills from fracking sites in only eleven states. When spilt, the effects of the chemicals used in the process of fracking on our vulnerable environment can wreak serious havoc on marine animals. Fish, which are very sensitive to even minute changes in environmental conditions, may hold the key to displaying just how toxic these fracturing fluid releases can be.
The History of Fracking
Fracking has been used for quite some time, however, techniques and equipment have advanced over this time to the hydraulic fracturing process that is used today. In 1862, during the Civil War, Colonel Edward A. L. Roberts discovered the first version of fracking in the middle of the battle field. He observed an increase in oil and natural gas flow after explosives were fired into water-filled canals, rupturing rocks below. In 1865, Colonel Roberts was awarded a patent for his discovery, known as "Exploding Torpedo", which contained the details of his oil and gas rich discovery. He called his theory superincumbent fluid tamping which entailed the lowering of an iron-cased torpedo into a well, setting it to explode, then filling the well with water to collect the flowing oil and gas. In 1947, Floyd Farris carried out an experiment to explore the relationship between oil sand gas collection and the pressure used in wells at Hugoton Gas Field, Grant County. His experiment used a mixture of gelled gasoline and sand however it yielded unsuccessful results and was considered a failure. Farris' experiment did however spark the beginnings of the idea of hydraulic fracturing, replacing explosives with pressurized liquid. In 1949, Halliburton found successful results from hydraulic fracturing experiments in Oklahoma and Texas and from there it became commercialized. In the 1990's drilling techniques were updated to increase oil and gas production and collection by increasing surface area in a technique called horizontal drilling created by George P. Michael. Hydraulic fracturing became popularized in the 21st century, in what is known as the "fracking boom". From the year 1940 to 2014, around a million wells were fractured but a third of those wells were fractured after the year 2000.  These advancements and experiments have led us to the hydraulic fracturing used in modern society.
Process of Fracking
The process of fracking begins after ensuring the chosen site can be properly accessed by equipment, and that prevention measures are put in place to counteract any possible spills as well as to allow rain drainage. Lots of water and chemicals are transported in separate trucks and mixed on site by a giant blender to create fracking fluid. Drilling can then commence starting with a vertical borehole which continues until the desired depth is reached then gradually turns ninety degrees to continue the borehole in what is called horizontal drilling. The well is cased with a steel pipe then cemented to prevent fluid movement in and out of the well. It is crucial for the cemented well to undergo rigorous testing to ensure it is fully sealed for the safety of nearby water systems. Once the well is complete, the drill is removed and either the casing is pre-perforated or a perforating gun is used to poke holes, about a few inches long, through the well, into the target rocks.
With the well completed, hydraulic fracturing can begin. Fracking fluid is pumped by frack pumpers into the newly made well under high enough pressure to deepen crevices in the target rock, as well as create new cracks. Once it is decided that the target rocks are fractured enough, the pump is switched off and pressure is slowly released. As pressure decreases, cracks in the rocks tend to want to close again, however, sand in the fracking fluid wedges into the crevices to prop them open. Oil and natural gas can now flow from the reservoir rocks they were trapped in, to the well. Fracking is normally done in ten to fifteen stages depending on the well length, starting with the furthest point in the horizontal portion of the well, moving towards the vertical portion of the well. This technique is called the multi-stage procedure meaning the furthest segment of the horizontal well is put under pressure by fracking fluid, then the next segment is put under pressure and so on. Multi-staging ensures maximum recovery of oil and natural gas from the reservoirs. Following multi-staging, production equipment can be brought in and installed. Oil and gas enter the well and can be pumped up to the surface along with a multitude of wastewater called flowback. Production equipment helps to separate resources from flowback fluid where it can either be reused in future fracking projects or disposed of in regulated sites. A well has the potential to continue oil and gas production for years. When no more oil or gas can be extracted from the well, it is filled in with concrete, all the equipment is packed up, and the site is left mostly as it was found.
Components of Fracking Fluid
Fracking fluid is crucial for creating, deepening, and propping open crevices in reservoir rocks. The key components of a good fracking fluid are a base, a proppant, and additives. The base is often made up of 97% water, but less commonly could also be liquid carbon dioxide or nitrogen. Per well, around two to six million US gallons of water are used and depending on the amount of stages used, could be more. The exact components of fracking fluid are widely unknown due to companies claiming it is "confidential business information". Some sort of uniformly shaped and sized sand, quartz, silica or ceramic beads are always present in hydraulic fracking fluid and are referred to as a "proppant". A "proppant" is essential for wedging into rock fractures and holding it open for oil and gas to flow out of when pressure is released. Other ingredients can be added to fracking fluid depending on the type of rock or the specific conditions of the well and are referred to as additives. Many additives are common in household items but carry out important purposes underground including
- Acid to dissolve minerals and allow oil and gas to flow more freely
- A gelling agent to lubricate fractures, ensuring proppants can reach every fracture
- Biocides to reduce or prevent the build up of bacteria.
- Surfactants to reduce surface tension and deter capillarity
- Polyacrylamide to lubricate the pipe and prevent friction
- Borate salts to maintain fluid viscosity with fluctuating temperature
- Citric acid to prevent pipe corrosion
- Guar gum to increase velocity so the proppant is suspended
Around 70-80% of fracking fluid is drawn out of the well after hydraulic fracturing meaning 20-30% of the fluid remains underground saturating rocks with the water and chemical additives.
Fracking Fluid and its Effects on Fish Health
Outcomes of the Kentucky Spill on Local Fish Species
In May and June, 2007, fracking fluid from four fracking sites spilled into Acorn Fork Creek, Kentucky, and contributed to the devastation of local Creek Chub, Sunfish and endangered Blackside Dace populations. The water quality in Acorn Fork Creek was greatly affected by the spills so researchers decided to study the effects it had on the remaining local fish population. Areas of the creek directly influenced by the spill were acidified from a pH of around 7 to a new pH of about 5.6, most likely due to the hydrochloric acid that made up part of the fracturing fluid. In addition, an increase in metals was detected in creek water increasing conductivity to an alarming level of 35,000µS/cm where normal conductivity is somewhere around 200µS/cm. It was also observed that following the spill an orange-red precipitate up to a few inches thick built up in parts of the creek. The peculiar build-up was thought to be rich in metals such as iron and aluminum. Researchers collected local fish from different areas of the creek with varying water quality levels due to the fracking spill, and compared it to the same species of fish under optimal water conditions. As fish were collected from the most heavily affected portions of the creek, researchers noticed behavioural abnormalities of fish including erratic swimming, bumping into surroundings, rocking back and forth in the shallows and not swimming away from dip nets. Tissue samples from the gills, liver, spleen, kidney and gonads were taken from the collected fish for examination. The gonads were used to sex the different fish and sort them into stages of development. Other organs like the gills and liver were observed under compound light microscope for lesions and other stress indicators then taken for further observation and testing. Researchers described that signs of stress and lesions can be detected on the collected organs. For example hepatic lipid levels or glycogen levels can indicate whether or not a fish has been exposed to a physiologically stressful environment. Disruption of metabolism by poor water conditions can alter biochemical levels which can be observed on vital organs. Almost all fish collected from creek areas of poor water quality, directly affected by fracking fluid, displayed epithelial hyperplasia in the gills meaning gill tissues were greatly enlarged. Swelling of gill lamellae can cause further problems like fusion of secondary lamellae which can affect respiratory and circulatory processes. Acidified water also disrupted ion transport at the fish's gill-water interface causing more respiratory distress. Portions of the creek where conductivity was high also housed fish that had trouble with osmoregulation, respiration and reproduction because metals had interfered with different enzymes in the biochemical processes. Overall, fish sampled from fracking fluid polluted waters of the creek had much higher levels of tissue damage, physiological and behavioural troubles when compared to fish sampled from water ways uncontaminated by fracking fluid. 
Zebrafish Embryo and Flowback Study
A study performed by Lavelle, M. (2018) explores the toxicological effects of hydraulic fracturing flowback fluid collected from sites on Marcellus Shale on the development of zebrafish embryos. Marcellus Shale is sedimentary rock created from mud and organic material under high pressure for millions of years, and stretches from New York to West Virginia and parts of Ohio, passing through Pennsylvania, USA. In 2017, 19,617 wells were documented in the area that were either active, abandoned or expected to be drilled meaning flowback fluid is abundant in the area.
Zebrafish embryos were studied as they develop quickly and hatch after only 48 hours. The embryos also remain transparent so physiological abnormalities or changes are easily observed without invasive procedures. Flowback collected from multiple wells on the Marcellus Shale were used to create holding tanks with different stages of dilution to submerge Zebrafish embryos. An initial problem was very high salinity within each dilution tank which in itself would harm the embryos. Salinity levels were balanced allowing observed effects to be solely based on toxicological effects of flowback, and not the salinity. Embryos were randomly submerged in either one of the dilution tanks or the control solution with optimal water conditions and observed every 24 hours. Throughout the experiment measurements such as LC50, lethal concentration, and EC50, median effective concentration, were collected. Lethal concentration represents the flowback concentration in water that kills 50% of the sample population and median effective concentration is the flowback concentration in water where 50% of the sample population develops malformations. It was found that when concentration of flowback was increased, zebrafish embryo heart rate also increased while the length of the fish decreased compared to the control embryos. It was also observed that head malformations were rampant with embryos that developed in any concentration of flowback fluid which further proved to affect jaw and mouth formation in later development stages. Malformations for treated embryos continued as caudal fin curvature was common relative to the control zebrafish. Overall, the study proved that even minute concentrations of flowback in local waterways can have great toxicological impacts on embryo development and future adult life for zebrafish in terms of physical deformities.
Offshore Fracking Effects on Mahi Mahi Swim Speed
Offshore hydraulic fracturing follows an almost identical process to onshore fracking in that pressurized fluid is forced into horizontal wells to extract oil and natural gas. A key difference between the two is that flowback fluid from offshore fracking wells is commonly dumped directly into the ocean. Due to the increasing concern for the Gulf of Mexico and the wildlife that live in the affected waters, an experiment was published in 2020 exploring the effects of flowback fluid on marine fish species, mahi-mahi.
Mahi-mahi were hatched and raised at the Miami Experimental Hatchery for experimental use. Flowback fluid was collected from the Duvernay Formation in Alberta, Canada. Swim tunnels were filled with varying dilutions of flowback fluid in seawater kept at constant temperature. Mahi underwent general health checks then were randomly added to the swim tanks, either containing dilute flowback fluid or control seawater. The swim tunnels were equipped to measure the critical velocity of mahi-mahi as well as oxygen consumption which gives information about metabolic rate. Data collected revealed that fish in the highest flowback water concentration tanks had 40% reductions in critical swimming speed relative to controls. Mahi in swim tanks with the most dilute flowback fluid concentration also suffered around 12% reductions in critical swimming speed in comparison to controls. Furthermore, mahi in the treated tanks consumed more oxygen on average and had overall higher metabolic rates and lower aerobic scope. Aerobic scope is the available energy an organism has beyond resting functions. To further explore the metabolic differences in mahi exposed to flowback water, cardiomyocytes or heart contractile cells were collected from ventricles. The cardiomyocytes were introduced to dilutions of flowback fluid similar to those used in the swim tanks to observe any consequences. A decrease in sarcomere shortening was observed which coincides directly with cardiac output. Sarcomeres are the smallest contractile units of each cardiomyocyte. The contraction length of sarcomeres is directly proportional to the stroke volume, or the volume of blood pumped from the heart to the body. The shorter sarcomere contraction length decreases the amount of blood and therefore oxygen delivered to the fish's muscles, forcing the heart to beat faster to keep up with metabolic needs. Offshore hydraulic fracturing practices are continually dumping toxic flowback fluid into the oceans and this experiment has proven the ingredients, even at low concentration have negative effects on the cardiac health of mahi-mahi.
Conclusion / Evaluation of Connection
The topics of geology and applied animal biology are not obviously connected but a little searching will uncover that the topics are intertwined in more ways than one. I chose the connection between hydraulic fracturing and fish health because they both affect and are affected by bodies of water respectively. Fish health is important in the topic of applied animal biology because they are very delicate organisms. Different species are only able to thrive in a small window of water conditions like certain pH, temperature, sediment level, etc. The health of fish populations are good indicators of water quality meaning when masses of fish are unhealthy most likely the water they reside in is poor quality whether it be by anthropogenic or natural causes. Hydraulic fracturing on the other hand is important in the topic of geology because it provides a means of extracting natural gas and oil from difficult spots to benefit the economy and to help continue providing resources for the advancement of technology. While fracking unlocks beneficial resources, it also leaves a lasting imprint on the environment, more specifically waterways. Fish and hydraulic fracturing are important topics together because we must find a balance where we can still support the economy while preventing the annihilation of sensitive fish habitats. Research points to fracturing fluid having multiple negative impacts on different fish species, and looking at the bigger picture it alludes to the fact that fracturing fluid is a negative addition to any water source, depreciating the quality. In the future I believe it would be intuitive to research possible additive substitutes that do not affect fish health, as well as brainstorming ways to minimize the amount of fracturing fluid being introduced to the environment. I believe there is a solution for hydraulic fracturing to exist where we can also uphold a plethora of healthy fish species.
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|This Earth Science resource was created by Alyssa J. Mar. It is shared under a CC-BY 4.0 International License.|