Guam and Palau Wrap Up: Another Successful Field Course Comes to an End

Originally published at ScientificAmerican.com

By David Ginsburg

Student scientific divers-in-training conducting underwater surveys off Catalina Island with transect tape and dive slates. Image: David Ginsburg

Recently, the 2013 Guam and Palau course came to a close. This is the fourth year that my co-instructor Jim Haw and I have run the program, which was offered for the first time in 2010. Since then, we have accompanied nearly 100 undergraduate students to Micronesia to investigate marine and coastal ecosystems (see link for details). This year’s cohort (26 students total) was our largest, and, arguably, one of the most accomplished (GPA ≈ 3.7) groups that we have worked with.

While traveling for three weeks to tropical and exotic locations with a group of fantastically bright and motivated undergraduate scientific divers-in-training is not always a guarantee of a successful field course, it certainly is an incentive. Similarly, the academic content and educational experience offered to students cannot be overlooked, and the Guam and Palau program is no exception.

Three essential educational approaches for the 2013 course included: 1) reflective writing, 2) situated learning in the field, and 3) teaching with technology. For several years running, we have had the opportunity to share the first two of these educational approaches with the Scientific American community in the form of student-driven blogs (a feat wholly attributed to Blog Editor Bora Zivkovic who gave us a lot of latitude on content this year – thank you!). The ‘teaching with technology’ component, however, is a new addition to the program in which we’ve geared up with iPads and GoPro cameras so our students can record, analyze, share, and interpret scientific data collected in the field. An outstanding example of this is a video blog by three participants (Justin Pearce, Lauren Stoneburner and Richelle Tanner) from this year’s course.

Volunteer dive instructor Tom Carr administering ear drops to Guam and Palau student scientific divers-in-training during our stay on Catalina Island. Image: Katie Lee

As described in Justin, Lauren, and Richelle’s video blog, the first leg of the 2013 Guam and Palau course started at the USC Wrigley Marine Science Center on Catalina Island. Each of the 26 student scientific divers-in-training spent an intensive week reviewing and practicing their in-water dive skills, which included advanced navigation techniques, as well as underwater survey and data collection methods. The students also were required to attend a series of daily lectures, which provided an overview of the course objectives, and a crash course in coral reef ecology, natural resource management, and marine governance.

During intensive periods of diving activity (diving multiple days in a row), the propensity for ear and sinus related maladies skyrockets. This year’s course was no exception as our ever-trusty volunteer dive instructor Tom Carr (whose day job includes time spent as a Reserve Deputy Sheriff and USC Hyperbaric Chamber Supervisor) was required to make the one-hour, windy, dusty drive to the Catalina Medical Center in Avalon with sick students at least once. With a little TLC and antibiotics all recovered just fine, though some were unable to dive for the duration of the trip.

The elephant ear sponge Ianthella basta is a common site along Western Shoals, which is located in Guam’s Apra Harbor. Although found in other regions of the Pacific, Ianthella is not known from any other location in Micronesia. Image: David Ginsburg

Arriving on Guam, there was a palpable excitement in the air. From the instructors’ standpoint, we were pleased to find all of our luggage and dive gear present and accounted for (nearly 60 pieces of baggage in total), whereas the students were just plain excited to be standing on a genuine tropical island (a US Territory, no less) on the other side of the world. For most of the kids, this was the furthest distance they had ever traveled from home, and for some, it was the first time they had ever left the US mainland. Course objectives on Guam included examining the impacts of overfishing and invasive species, conservation management, as well as the ominous military buildup (especially amongst the extensive coral reef habitats within Apra Harbor: see link for Apra Harbor video blog).

Our first full day on Guam started with an old friend and colleague Brent Tibbatts and his colleagues at the Guam Division of Wildlife and Aquatic Resources in Mangilao. Brent and the GDWAR staff provided our students the opportunity to interact with critically endangered birds (e.g., Guam Rail and Micronesian Kingfisher), mammals (e.g., Micronesian Fruit Bat), and handle a juvenile Brown Tree Snake, an invasive and mildly venomous viper.

Guam and Palau students Michael Young (L) handling an invasive juvenile brown tree snake and Caitlin Martin (R) holding an endemic Guam rail at the Division of Wildlife and Aquatic Resources headquarters on Guam. Images: Tom Carr

It should be noted that students went from holding one of the world’s rarest birds (i.e., endemic Guam rail) to handling the very animal (i.e., invasive brown tree snake) responsible for their demise. Later in the week, Brent took us on a tour of the Masso Reservoir located in the Asan-Piti Watershed where the students learned first-hand about the interplay between terrestrial and coastal resources and the importance of ‘ridge-to-reef’ management.

After four days on Guam, we boarded a plane and made our way to Palau where we arrived just in time to eat a late dinner. If the students were excited to arrive on Guam, they were beyond ecstatic to make it to Palau, as I had been telling them for months about how the diving in this region is amongst the best in the world.

Guam and Palau scientific divers-in-training conducting belt-transect fish surveys on Ngederrak Reef post Typhoon Bopha. Image: David Ginsburg

One of our primary objectives for this part of the course was to provide course participants with hands-on research experiences involving marine ecology, natural resource management, and policy issues. Faculty and students assisted Koror State Conservation and Law Enforcement officials and the Coral Reef Research Foundation in their ongoing efforts to monitor and survey the ecosystem health of Ngederrak Reef (a highly restricted marine protected area) and other reef sites within the recently established UNESCO Rock Islands Southern Lagoon World Heritage site.

This is a tremendous opportunity for our students who have benefited from working in real-time with local resource managers and scientists in the field. It should be noted that the Koror State Governor’s office and Conservation and Law Enforcement staff went above and beyond to host our group both on land and in the water.

Michele Felberg (L) and Nate Kinsey (R) monitoring Typhoon-ravaged reef located near Ngerchong Island, which is one of the Rock Islands between Koror and Peleliu. Image: David Ginsburg

This year’s Palau component of the course was by far one of our most productive and successful learning and research experiences in course history. Environmental survey data collected on this recent excursion (combined with 2011 and 2012 baseline surveys) will be instrumental in evaluating the recovery of coral reef resources damaged by Typhoon Bopha.

We hope to continue to assist Koror State in the coming months in the monitoring of physical and biological parameters at each of our study locations. In Summer 2014, we propose adding a “service learning” component to the course in which USC students (in conjunction with Koror State Officials) visit local elementary and secondary schools to discuss marine biology related themes, and Palau’s role as a global leader in marine conservation and sustainability.

By the time we finished our underwater field surveys, the students had clearly earned a “fun” dive or two. Our final dives in Palau included two of my favorite dive locations: Blue Corner and Ulong Channel. Blue Corner features a wedge-shaped reef with vertical wall drop-offs on either edge. The contour ensures an active upwelling on the leading edge relative to any prevailing current, which draws high densities of bumphead parrotfishes, napoleon wrasses, and other reef fishes, as well as a wide diversity of reef sharks. Take my word, there is a reason why Blue Corner is consistently listed as one of the top dive sites in the world; it is a show stopping experience every time! Not to be outdone, Ulong Channel, a world-class drift dive, is equally impressive. As my co-instructor Jim Haw described the experience, “divers are swept through the channel like aircraft flying up a canyon.”

Close encounter with a Manta Ray in German Channel. Image: David Ginsburg

At this time of the year, Ulong is notorious for it’s spawning aggregations of grouper, nesting triggerfish, and the ever present white tip and gray reef sharks that congregate in the mouth of the channel. Perhaps one our best highlights underwater was on our final dive in German Channel (another world-class dive spot) where we spent much of the dive with three very inquisitive Manta Rays!  Special thanks to Sam’s Dive Tours for their patience and support of our in-water diving activities boat needs.

Student divers showing off the USC flag in Ulong Channel. Image: David Ginsburg

In summary, this year’s course was a great success. By all accounts, it exceeded expectations (which were already high) on all fronts. Students gained valuable experience working hands-on in the field with local scientists and resource managers. Students often incorporate knowledge better and understand topics more fully by actively being engaged in an activity rather than only reading or writing about a concept. By engaging with local stakeholders involved in integrated ecosystem and conservation management, including fishermen, residents, tourism operators, park rangers, and government policy makers, students gain a better appreciation for the socio-political complexities involved in policy enforcement, and long-term monitoring and evaluation.

Southern California and Endangered Abalone Populations

Originally published at ScientificAmerican.com

By Megan Herring

Southern California’s beaches, sun, tranquility, and other resources makes it a prime area for people looking for a new place to plant roots and make their fortune. For this reason, California has seen a rapid growth in population and commerce, which has led to a number of positive effects on the California people and economy. With more people living and traveling to the state the economy has seen a huge boom leading to an increase in industry and comforts for those who live in California. Unfortunately, this success hasn’t come without a price; the golden state has begun to experience some of the negative consequences of its economic and social growth. Unsustainable resource extraction and environmental damage have become worrisome topics to many environmentalists as well as business owners who rely on these resources to sustain their livelihoods.

Abalone range in size from 5-12 inches in length and are found in coastal waters. Image: NOAA photo library.

One such consequence of California’s economic and population boom involves the decrease in population of abalone, a type of mollusk, in southern California. There are many different species of abalone including the white, black, red, and green abalone, which can all be found off the coasts of California and Mexico. Using a muscular foot, the marine gastropod is able to hold onto a rocky surface where they scrape off algae from the ocean floor for food.

Abalone were once a common site for divers in the area, especially around Catalina Island, just off the coast of Los Angeles, but they have seen a large decrease in population. Species such as the white and black abalone are now listed as endangered. As abalone have begun to decrease in numbers the health of coastal food webs has deteriorated as well. The abalone help to keep the population of algae low enough so as to decrease the chance for algal blooms in the ocean, which can block sunlight to the ocean floor resulting in a decrease in the amount of oxygen created by photosynthetic organisms, which is essential for other animals. Also, with the decreasing number of abalone, secondary predators such as sea stars and sea lions that rely upon them as a source of food will be forced to find other prey or starve. This could lead to a decrease in both the number of predators and a decrease in other animals that become targeted prey in the absence of the abalone. By taking abalone out of the food chain the oceans are facing serious risks, and many of these risks are, as in many situations, anthropogenic. In addition, due to their slow growth rate and inefficient spawning, abalone in general find it challenging to recover from recent traumas, such as overharvesting and disease, that have damaged populations of the mollusk (Stierhoff et al., 2010).

White abalone are found primarily along the coast of Southern California and Northern Mexico. Red, green, and black abalone are found in this region as well, but can also be found further north. White abalone were the first invertebrates to be listed as endangered under the ESA followed by the black abalone. Image: NOAA photo library.

Abalone are economically important for two major reasons. First, abalone shells are beautiful when polished and are often used for ornaments or jewelry. Second, their muscular foot that is used to attach to substrate is considered a delicacy, making the mollusk popular among consumers. As demand has increased for abalone, though, the abalone has been at risk of being overharvested. Species like the white and black abalone are now endangered, while others such as the green and red abalone are steadily decreasing in number.

These declines have led to a number of laws that strive to protect the small number that remain from being harvested to a point where they cannot recover (Stierhoff et al., 2012). One such law is that abalone may only be harvested via skin diving, or diving under the water on one breath of air, and must be a certain size depending on the area—no SCUBA equipment may be used to harvest abalone. There are also a number of abalone fisheries that have been set up within California to help meet the increasing demand for abalone meat. Fisheries allow for the abalone to be raised and harvested through aquaculture to help mitigate the amount of wild abalone that are harvested each year (California Department of Fish and Wildlife).

That being said, the road to saving the abalone is not an easy one. Abalone are easily overharvested as they take a long time to grow and have low reproductive success. Few abalone can now be found in the two to five inch range, which shows that little significant reproduction has occurred. Off the coast of Northern California the growth rate of the red abalone is so slow that many will not be of legal harvest size for another ten years. Many fishermen poach abalone and in many fishing areas abalone shells can be found that are well below the legal size that fisherman can take, leading to the death of many undersized abalone that have not even reached reproductive age (Daniels and Floren, 1998).

Another major obstacle to abalone recovery that does not involve humans is an infectious disease called withering shell syndrome. This disease is almost impossible to detect in abalone until the mollusk actually dies. Caused by the bacterium Candidatus Xenohaliotis Californiensis, the disease has been studied in a number of laboratories and fisheries. A cure has not been found because the disease is hard to detect until the mass mortalities of abalone begin in certain areas. The disease has been seen mostly in the black abalone populations in Southern California and in the red abalone populations in Northern California. Currently there is a great push for more research into this disease and the possible ways to save the abalone population, which includes establishing more protected habitat, as well as better protecting “non-threatened” abalone species. Over the last decade, white abalone populations have decreased by as much as 80% leading many researchers to label this species as ‘functionally extinct’ along the Southern California coast (Friedman and Finley 2003).

Marine protected areas or MPAs have been created within Southern California in order to try and conserve many endangered species, including the abalone, from overharvesting, allowing for many species to recover from past harm. The goals of MPAs are to sustain the biological community in that area as well as allow for economic resources, such as sought-after fish, to recover from past traumas. There is one MPA located on Catalina Island near Two Harbors where the USC Wrigley Marine Center is located, allowing for better collection of scientific data. There are also two other MPAs on the coast of southern California that were carefully chosen to protect abalone and other vulnerable species while limiting the economic impact to the local community (Stockstad, 2010). Some believe that more research needs to be focused on where to locate MPAs so as to create the best environment to try and stabilize the abalone populations (Rogers-Bennett et al., 2000). Finding suitable locations should be a priority because researchers are now trying to culture wild abalone to foster viable offspring, especially for the endangered white abalone. Unfortunately, unless these juveniles have a protected habitat to settle and grow, such propagation efforts may be futile. Abalone play an important role in subtidal benthic marine ecosystems; without them a crucial part of the marine food web will potentially be lost forever.

Author Bio: Megan Herring, originally from Missoula, Montana, is a freshman at USC Dornsife majoring in Biology and Creative Writing.

Works Cited

California Department of Fish and Wildlife. “California Abalone Information.” Web. 24 May 2013.

Daniels, R., and R. Floren. “Poaching Pressures on Northern California’s Abalone Fishery.” Journal of Shellfish Research. Vol. 17. National Shellfisheries Association, 1998. 859–862. ProQuest. Web. 22 Mar. 2013.

Friedman, Carolyn S., and Carl A. Finley. “Anthropogenic Introduction of the Etiological Agent of Withering Syndrome into Northern California Abalone Populations via Conservation Efforts.” Canadian Journal of Fisheries and Aquatic Sciences 60.11 (2003): 1424–1431.

Rogers-Bennett, L., P. Haaker, and K. Karpov. “Selecting and Evaluating Marine Protected Areas for Abalone in California.” Journal of Shellfish Research. Vol. 19. National Shellfisheries Association, 2000. 530–531. ProQuest. Web. 22 Mar. 2013.

Stierhoff, Kevin L., Melissa Neuman, and John L. Butler. “On the Road to Extinction? Population Declines of the Endangered White Abalone, Haliotis Sorenseni.” Biological Conservation 152 (2012): 46–52. ScienceDirect. Web. 25 Mar. 2013.

Stokstad, Erik. “Science Meets Politics Off California’s Coast.” Science 327.5973 (2010): 1574–1575. www.sciencemag.org.libproxy.usc.edu. Web. 26 May 2013.

Editor’s note: Scientific Research Diving at USC Dornsife is offered as part of an experiential summer program offered to undergraduate students of the USC Dana and David Dornsife College of Letters, Arts and Sciences through the Environmental Studies Program.   This course takes place on location at the USC Wrigley Marine Science Center on Catalina Island and throughout Micronesia. Students investigate important environmental issues such as ecologically sustainable development, fisheries management, protected-area planning and assessment, and human health issues. During the course of the program, the student team will dive and collect data to support conservation and management strategies to protect the fragile coral reefs of Guam and Palau in Micronesia.

Instructors for the course include Jim Haw, Director of the Environmental Studies Program in USC Dornsife, Assistant Professor of Environmental Studies David Ginsburg, Lecturer Kristen Weiss, SCUBA instructor and volunteer in the USC Scientific Diving Program Tom Carr and USC Dive Safety Officer Gerry Smith of the USC Wrigley Institute for Environmental Studies.

The Historical Collapse of Southern California Fisheries and the Rocky Future of Seafood

Originally published at ScientificAmerican.com

By Katie Lee

Recently, the New York Times Green Blog described how two major Southern California fisheries (kelp and barred sand bass) had collapsed “right under the noses of management agencies.” The management and oversight of these fish stocks had not changed since 1959. This news is perhaps not surprising as there are more examples of marine species collapses off our coastline than possible to list in this blog post.

Though the media tends to focus on the effects of pollution, climate change, or overfishing, outdated systems of management are actually the main cause of the collapse in many cases.

Palos Verdes Peninsula, home to crucial abalone stocks. Source: Tegner

The ups and downs of abalone stocks off of the coast of Southern California provide an example of how poor fishery management resulted in the collapse of a population. Only a few years after the Palos Verdes Peninsula abalone stocks re-opened for commercial fishing in 1943, the stocks began to decline again, as more than 9.3 million pink abalone were collected during the peak decade of the fishery (Taniguchi 2013).

These waters are home to one of the largest kelp forests in the Pacific, and this giant kelp (Macrocystis Pyrifera) is the main food source for abalone, sea urchins, and many other fish and marine mammals. Because of a spike in population growth after World War II, a greater amount of sewage was discharged into the water, leading to the deterioration of kelp forests. This pollution, combined with a warmer water temperature because of the 1957 El Niño event, rendered the kelp forests practically extinct, which meant to loss of abalones’ main food source.

Therefore, because of a lack of food, the abalone either did not reproduce or had badly weakened shells and stunted growth. Even after the kelp gradually grew back and abalone populations increased because of stricter regulations, poaching became a huge problem. Because abalones are found in predictable, accessible locations, and because they have a high unit value, the value of individual animals outweighed any risks or penalties for poaching. Enforcement of the laws was minimal because of California’s small environmental budget—there were only five wardens responsible for monitoring “hunting, fishing, exotic animals, [and] pollution events” for the entire inland Los Angeles County (Tegner 1993).

Example of an Abalone shell. Source: Mynzah.com

Since 1977, this fishery has been closed to sport and commercial take of abalones along parts of the California coastline. Yet this closure has not led to abalone population recovery because the off-limit areas were not located in areas with existing abalone stocks, so recolonization was not possible. Neither was poaching was not heavily monitored (Tegner 1993). Recent research has also found that opening up abalone reserves to fishing can result in immediate and drastic declines in abalone density, size, and reproductive capacity (Rogers-Bennett 2013). Perhaps only with time and new management strategies will abalone populations have a chance to recover.

The history of the California sardine fishery is another example of failed regulations and drastic overfishing. The fishery began in the late 1800s, developed in response to a demand for food because of World War I. People canned and reduced the fish for food and oil, with small amounts used for live and dead bait. As the fishery grew and expanded, environmentalists and scientists recommended there be a catch limit of 200,000 tons, but since there seemed to be an endless supply of fish, no one listened.

School of sardines. Source: opb.org

From the 1930s to 1940s, the pacific sardine fishery was the largest in North America, but after just a few years, it totally collapsed. From a catch of over 790,000 tons in 1936 to less than 100 tons in the 1970s (Wolf 1992), the sardine fisheries clearly needed better regulations.

In 1967, decades after the fishery had collapsed (Wolf 1992), California passed an emergency bill declaring a two-year moratorium on the harvest of sardines. It was a much-needed acknowledgement that the fishery was no longer viable (Wolf 1992), and gradually the sardine populations began to increase again. The quota limit increased as the fish populations increased, and then would decrease as the populations declined again.

This system of waiting until the fish populations collapse to put in fishery regulations, and then allowing a free-for-all once they recover slightly, will not last in the long term. It is a ‘too little too late’ policy that eventually will result in either extinction or endangerment of animal species.

Though these two fisheries are now managed with the future of the fish populations in mind, and the government and fishermen appear to have learned from the past, there are still countless fisheries off of Southern California that have collapsed, even within the past few years. Many people blame this surprising decline on something called “hyperstability.” It’s a phenomenon where a high catch rate masks a decline in actual population of fish because the fish tend to spawn and congregate in large masses, giving an “illusion of plenty” (UC San Diego 2011). Though the fisheries are now required to tightly monitor the stock of fishes, because the fish congregate in large masses in certain places, their data is always too high a number.

The persistent over-fishing and consistently high catch rates are what lead to the collapse, in addition to the gradual warming of the water since 1980. If we want to preserve the ocean’s beauty and continue to eat sushi, fisheries need to not rely purely on catch rates to determine fish population level, both in Southern California and the rest of the world.

A combination of scientific research and constant monitoring must be incorporated into fisheries management before the fish population collapses. Even with fish populations displaying extraordinary declines and recoveries, human interferences should never cause such drastic changes in marine life, and people need to immediately take a lesson from the past and implement stricter catch quotas worldwide.

The future of seafood and entire marine ecosystems is not at all certain, and based on past mistakes, stricter regulations and more consistent, updated research are the keys to ensuring that these species that we rely on for food, science, and natural beauty never go extinct.

Author Bio: Katie Lee is a freshman at the University of Southern California’s Dornsife College of Letters, Arts, and Sciences. She lives in Kauai, Hawaii but would reside in the waves if she could. She is currently pursuing a B.S. in Environmental Science and Health with a minor in Business, and hopes to save the oceans in the near future.

References:

Laura Rogers-Bennett, Kristin E. Hubbard, Christina I. Juhasz, Dramatic declines in red abalone populations after opening a “de facto” marine reserve to fishing: Testing temporal reserves, Biological Conservation, Volume 157, January 2013, Pages 423-431.

Taniguchi, Ian K., et al. “Testing translocation as a recovery tool for pink (Haliotis corrugata) and green (Haliotis fulgens) abalone in Southern California.” Journal of Shellfish Research 32.1 (2013): 209+. Academic OneFile. Web. 24 May 2013.

Tegner, M.J.1993. Southern California Abalones: Can Stocks Be Rebuilt Using Marine Harvest Refugial Can. 1. Fish. Aquat. Sci. 50: 2010-201 8.

Wolf, Patricia. “Sardine Recovery and the California Sardine Fishery.” California Department of Fish and Game, Rep., Vol. 33, 1992.

Editor’s note: Scientific Research Diving at USC Dornsife is offered as part of an experiential summer program offered to undergraduate students of the USC Dana and David Dornsife College of Letters, Arts and Sciences through the Environmental Studies Program.   This course takes place on location at the USC Wrigley Marine Science Center on Catalina Island and throughout Micronesia. Students investigate important environmental issues such as ecologically sustainable development, fisheries management, protected-area planning and assessment, and human health issues. During the course of the program, the student team will dive and collect data to support conservation and management strategies to protect the fragile coral reefs of Guam and Palau in Micronesia.

Instructors for the course include Jim Haw, Director of the Environmental Studies Program in USC Dornsife, Assistant Professor of Environmental Studies David Ginsburg, Lecturer Kristen Weiss, SCUBA instructor and volunteer in the USC Scientific Diving Program Tom Carr and USC Dive Safety Officer Gerry Smith of the USC Wrigley Institute for Environmental Studies.

Hyperbaric Oxygen: A Spectrum of Emerging Treatments

Originally published at ScientificAmerican.com

By Nathalie Sami and Janice Wong

The hyperbaric chamber on Catalina Island at the USC Wrigley Marine Institute.

Certified scuba divers are familiar with the use of hyperbaric oxygen therapy (HBOT) for decompression sickness treatment. However, in the past 50 years, researchers have revealed HBOT’s broad applications to human physiology and medicine. The outlook for HBOT applications for treating wounds, neurological diseases, and even certain cancers appears promising. What once seemed relevant only for scuba divers has now been discovered to benefit members of the general population.

Background

HBOT involves the administration of pure, 100% oxygen in a compression chamber at pressures above atmospheric levels. The resultant increase of oxygen content in blood yields a broad variety of physiological effects, because increased pressure allows oxygen to saturate more effectively in the body. For scuba divers, this increased oxygen pressure reduces the volume of inert-gas bubbles in blood vessels, reversing air embolism or decompression sickness (Danesh-Sani et al. 2012). Moreover, researchers have described several beneficial influences of HBOT on healing damaged tissues: increased white blood cell activity, reduced swelling, healing time reduction, tissue regeneration, and even synergistic activity with antibiotics (Strużyna et al. 2008). The Undersea Hyperbaric Medicine Society recommends many applications for HBOT that have proven successful (Table 1). Beyond these now standard uses, several novel research areas demonstrate further beneficial HBOT applications. HBOT applications to wounds, cancers, and neurological and vascular diseases will be discussed below.

Wounds

Low oxygen content caused by swelling or burns reduces PH and prohibits wound healing. On the other hand, higher oxygen tension improves healing of wounds by stimulating tissue-forming cells (Danesh-Sani et al. 2012). Hyperbaric oxygenation of wounds thus initiates wound-healing events such as tissue and cell generation and resistance to infection (Shah 2010). Furthermore, oxygen helps fight against infections by killing bacteria that cannot tolerate oxygen (Youn 2001). For example, in treating injuries as common as burns, HBOT reduces healing time and number of infections (Strużyna et al. 2008).

Cholesterol Crystal Embolism (CCE)

(A) Physical lesion at presentation; (B) worsening of lesions after 1 month of treatment; and (C) complete resolution of necrotic lesions after 1 month of HBOT (Gurgo et al., 2011).

Such benefits also apply to patients of cholesterol crystal embolism (CCE), a disease with a high mortality rate. In a case study of a 56-year-old man who developed CCE and who had already undergone an unsuccessful standard treatment, HBOT caused rapid improvement. As seen in Fig. 1, after two months, complete recovery was obtained, leading the authors to conclude that HBOT may serve as an effective treatment in CCE (Gurgo et al., 2011).

Bone Healing

Another known application for HBOT is with bone healing, during which HBOT increases white blood cell activity and tissue formation (Danesh-Sani et al. 2012). Also, HBOT may induce the formation of new blood vessels by stimulating an increase of stem cells within the tissues (Shah 2010). An application of bone-healing effects regards the influence of HBOT on bone tissue after the cessation of smoking. Smoking has proven to delay bone healing and impair blood circulation; however, HBOT mitigates the effects of smoking on bone healing, now proving that bone damage caused by smoking may be reversible (Yen et al. 2008).

Surgery

Surgical injuries present yet another opportunity for HBOT intervention. Danesh-Sani and colleagues (2012) asserted that use of HBOT before surgical treatment significantly reduces risk of postoperative infection and accelerates healing, and other studies demonstrate benefits of post-operative HBOT application. In the case of urethral reconstructive operations, which commonly cause decreased erectile function, findings suggest that HBOT stimulates the regeneration of injured nerves and promotes tissue formation to allow erectile function recovery (Yuan et al. 2011).

Cancers

Solid tumors, which are often hypoxic, can increase genetic instability and activate invasive growth to exacerbate certain types of cancer (Moen & Stuhr 2012). By providing oxygenation, HBOT induces excessive oxygenation, which causes rapid degeneration and tumor cell destruction. As a result, HBOT is thought to yield beneficial effects in several types of tumors with minimal invasiveness (Danesh-Sani et al. 2012). As well, HBOT could improve and help overcome chemotherapeutic resistance by increasing cellular sensitivity to radiotherapy (Moen & Stuhr 2012).

Breast and Prostate Cancer

The adjunctive use of HBOT with chemotherapy has shown positive effects on reducing breast cancer. As the most frequently occurring cancer in women, breast cancer provides a worldwide threat, and HBOT has shown a strong effect against different mammary cancer cells. HBOT has also led to less aggressive and restricted growth of large tumor cell colonies (Moen & Stuhr 2012). Successful experiments regarding prostate cancer cells with HBOT have also generated affirming results. Cancer of the prostate is the second leading type of cancer for men, and in vitro experiments have demonstrated the efficacy of HBOT in decreasing the cancer cells’ growth rate and increasing their sensitivity to chemotherapy (Moen & Stuhr 2012).

Neurological Diseases

The success of recent studies regarding the use of HBOT in improving neuromuscular pathologies has merited further investigation to confirm its beneficial uses and mechanisms.

The most evidence-supported neurological application for HBOT lies with autism spectrum disorders (ASD), which is currently diagnosed in 1 in 88 children in the US (CDC 2012). ASD includes neurodevelopmental disorders characterized by restrictive and repetitive behaviors as well as impairments in communication and social interaction. Several experiments involving the effects of HBOT on children with autism have reported clinical improvements, citing decreased inflammation and improved blood circulation to the brain. One study resulted in improvements in overall functioning for 80% of autistic children treated with HBOT, leading to the conclusion that HBOT is a safe treatment for as prevalent a neurological disease as ASD (Rossignol et al. 2009).

Vascular Diseases

HBOT may reduce the symptoms of vascular diseases by improving circulation and oxygenation.

Vascular Dementia

For instance, vascular dementia, caused by decrease blood flow to the brain, is characterized by loss of memory, confusion, problems with speech and understanding, and an increased dependence on others. While no effective treatment has been established, models have demonstrated HBOT’s ability to improve blood supply and promote nerve tissue formation in the brain and enhance learning and memory. One study found that patients receiving HBOT exhibited better cognitive function than patients of the control group after 12 weeks of treatment (Xiao et al. 2012).

Carbon Monoxide Poisoning

HBOT is also used to treat carbon monoxide poisoning. Usually, hemoglobin proteins in red blood cells transport oxygen. However, carbon monoxide binds more readily to hemoglobin than oxygen.  As a result, the body is unable to distribute oxygen throughout the body when exposed to carbon monoxide resulting in hypoxia (Mills and Saulsberry, 2011). HBOT is effectively used to reverse this harmful effect.

Arterial gas embolisms and stroke

One of the common uses of HBOT is to treat arterial gas embolisms. An arterial gas embolism is when that gas in the circulatory system goes through arteries or pulmonary veins and blocks blood flow (Muth and Shank, 2000). In non-diving accidents the cause of arterial gas embolisms are caused by medical mistakes such as accidentally injecting air in patients. These escaped bubbles are very dangerous because they block blood flow to certain areas, resulting in hypoxic tissue. In the brain, reduced blood and oxygen flow can cause a stroke and brain damage. Acute stroke results from impairment of blood flow to the brain, which causes neuron cell death. HBOT may increase available oxygen and reduce brain swelling to prevent further neuron damage (Bennett et al. 2010). Stroke is a leading cause of death in the US, so these discoveries may yield huge implications. Hyperbaric medicine is effective in treating these problems because raising the pressure of the chamber causes the size of gas bubbles to decrease (Bell and Gill, 2004). In addition to the reduction in bubble size, oxygen can more easily dissolve to benefit the previously hypoxic environment (Muth and Shank, 2000).

Insulin Sensitivity

Another study proved that HBOT creates a substantial increase in insulin sensitivity. The improvement occurs rapidly (e.g., within three treatments) and is sustained at least until the thirtieth treatment. HBOT may induce insulin sensitivity by oxygenating fat tissue and reducing inflammation (Wilkinson et al. 2012). This discovery could have important implications, because insulin insensitivity is associated with diabetes, high blood pressure, heart disease, obesity, and certain types of cancer, which cause the majority of deaths in America (Colberg 2008).

Risks

While HBOT provides many beneficial treatments, there are some associated risks, such as oxygen toxicity. Metabolizing oxygen releases highly reactive byproducts that build up over time and saturate in tissue with increasing pressure. Resulting oxygen toxicity can lead to respiratory issues and seizures, because the toxicity often affects the lungs and central nervous system (Almeling et al. 2000).  Another risk commonly associated with HBOT is barotraumatic lesions, the result of unequal pressure between the outside and inside of an air containing space. For humans, the middle ear most commonly experiences barotrauma, but other areas include lungs, nasal cavities and sinuses, inner ears, and teeth (Almeling et al, 2000). Equalizing during treatment is important, because people who are unable to equalize their ears during HBOT can experience middle ear barotrauma (Undersea and Hyperbaric Medical Society, 2011). Middle ear barotrauma, the most common side effect of HBOT, occurs when the pressure outside the ear is greater than the pressure of the middle ear.

Conclusion

While there are some risks associated with hyperbaric treatment, careful administration and thorough monitoring can limit the risk of side effects of HBOT. Although HBOT has not yet been adopted as the primary treatment for many of the mentioned conditions, it provides a minimally-invasive opportunity for treatment. The discovery of HBOT’s physiological benefits has demonstrated implications for treating the most prevalent ailments in the US. Thus, the newly-proposed, broadly-reaching benefits of HBOT applications beyond diving injury treatment merit deeper investigations. Indeed, with so many potential treatment functions, HBOT has earned its reputation as “a therapy in search of diseases” (Danesh-Sani et al. 2012).

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About the authors:

Nathalie Sami is a rising sophomore majoring in Environmental Science and Health in the USC Dana and Dornsife College of Letters, Arts, and Sciences. Her interests include playing, coaching and watching basketball, learning about sustainable lifestyles, and volunteering at health sites.

Janice Wong is an incoming sophomore majoring in environmental science and health at the USC Dana and David Dornsife College of Letters, Arts and Sciences.

Editor’s note: Scientific Research Diving at USC Dornsife is offered as part of an experiential summer program offered to undergraduate students of the USC Dana and David Dornsife College of Letters, Arts and Sciences through the Environmental Studies Program.  This course takes place on location at the USC Wrigley Marine Science Center on Catalina Island and throughout Micronesia. Students investigate important environmental issues such as ecologically sustainable development, fisheries management, protected-area planning and assessment, and human health issues. During the course of the program, the student team will dive and collect data to support conservation and management strategies to protect the fragile coral reefs of Guam and Palau in Micronesia.

Instructors for the course include Jim Haw, Director of the Environmental Studies Program in USC Dornsife, Assistant Professor of Environmental Studies David Ginsburg, Lecturer Kristen Weiss, SCUBA instructor and volunteer in the USC Scientific Diving Program Tom Carr and USC Dive Safety Officer Gerry Smith of the USC Wrigley Institute for Environmental Studies