Daniel C. Abel, Ph.D., is a professor of marine science and the founding director of the Campus and Community Sustainability Initiative. He joined the Coastal Carolina University faculty in 1994. He earned bachelor's and master's degrees from the College of Charleston in 1978 and 1981, respectively, and a Ph.D. in marine biology from Scripps Institution of Oceanography in 1986. He is co-author of the environmental science textbooks,"Environmental Issues in Oceanography" and "Environmental Issues: An Introduction to Sustainability." His research interests include surveys of sting rays and sharks along the Southeast coast.
Q: What courses have you taught at CCU?
- Introduction to Science (lecture and lab).
- Intro. to Environmental Science (lecture and lab).
- The Sea (lecture and lab).
- Environmental Geology (lecture and lab).
- Intro. to Marine Science (lecture and lab).
- Origin and Evolution of the Marine. Environment (lecture and lab).
- Scientific Communication.
- Honors Service Learning: Habitat for Humanity Green Building Project.
- Marine Biology (lecture and lab).
- Biology of Sharks (lecture and lab, international component).
- Apex Predators and Other Endangered Wildlife (team-taught).
- Marine Physiological Ecology.
- Rescuing Planet Earth.
- Marine Science for Elementary School Teachers (lecture and lab).
- Aquatic Physiological Ecology (lecture).
- Earth System Science for Teachers (lecture and lab).
Q: When did you start the shark program and why?
The shark program at CCU was launched in 1997 when I offered my first Biology of Sharks education abroad course at the Bimini Biological Field Station in the Bahamas. I began to focus on sharks as the subject of my scholarship during my four years of graduate school at Scripps Institution of Oceanography in La Jolla, Calif. My dissertation on heart function in sharks combined my two scholarly passions, physiology and ecology, and introduced me to numerous Pacific Coast sharks, including White Sharks, Shortfin Makos, Horn Sharks, Leopard Sharks, Blue Sharks, Smoothhounds, Swell Sharks, and others. It was thus natural for me to continue studying sharks. What further motivated me to start the program, which expanded in 2001 to include a major research component and transformed into the CCU Shark Project, were the magnificent local ecosystems (particularly Winyah Bay and North Inlet whose shark fauna had been unstudied) and the passion of CCU marine science students to learn about these magnificent beasts. Combine these with threats that humans pose to sharks and their oftenunrecognized roles in their ecosystems, and just how cool they are, and I was left with no choice but to start the program.
Q: What methods do you use in your research, and where do you do the research?
To study sharks, we first must catch them. To do this, we rely on longlining, the same technique used by commercial fishers. Our longlines are about 152 m (500 ft) long and consist of a rope or monofilament mainline to which are attached 25 to 50 gangions, the branches containing the baited hooks. We use a variety of hook sizes, up to the monstrous 18-0 (eighteen-aught) size, to target the entire range of sizes of sharks in local estuarine ecosystems, from 0.3 m (12 in) newborn Atlantic Sharpnose Sharks to > 3-m (9.8 ft) Lemon Sharks. We leave the longlines in the water (we say that we soak them) for about an hour, typically baited with Boston Mackerel, and we catch from zero to as many as 15 sharks per longline. Our long-term average is about two sharks per line. Lately we have been targeting bigger species, like Bull and Lemon Sharks, which we have long felt were under-represented in our surveys. To catch these sharks, we set drum lines, which have a single hook and the biggest monofilament (1,200-lb test) available. In the summer and early fall of 2019, we caught more Bull Sharks in Winyah Bay than in the previous 18 years combined.
One of our research directions is to understand how the sharks we catch select the habitat they occupy, so we collect a variety of data before and after every longline. These data include Secchi depth (an indicator of water clarity), and surface and bottom temperature, salinity, and dissolved oxygen concentration. We also note the tidal stage. We measure, tag, take blood other tissue samples, and quickly release the sharks. If the sharks are in good shape, we will take a few minutes to educate students about them, and teach students how to handle a shark.
In addition to longlines, we have employed gill nets and tangle nets and have also used hook-and-line fishing.
Since determining where sharks move is important to understanding their ecology, we tag individuals of most species. Conventional tags that we use include roto-tags, which are similar to livestock ear tags, affixed to the dorsal fin, and stainless steel dart tags anchored in the muscle. These are provided to us by the National Oceanic and Atmospheric Administration (NOAA). We rely on the goodwill of the recreational or commercial fisher who catches the shark to call or email NOAA with the capture location and date, as well as other information, such as the total length of the shark. NOAA subsequently provides recapture data to us. Recapture rates are in the low single digits.
A major weakness of the conventional tagging described above is that at best you get information only between the initial capture and subsequent recapture. For finer resolution of shark movement, we use acoustic (sound wave) telemetry. We use both active and passive acoustic tracking. In both cases, an acoustic tag, that is, a transmitter, is either surgically implanted in the abdomen of the shark or is affixed to the shark’s exterior. The tags ping at low intensity at a frequency between 35 and 80 kHz.
For active tracking, we use a hydrophone mounted on the bow of a skiff, and we follow the aural pings while noting the location. In passive tracking, individual sharks are not followed but rather are detected by acoustic receivers that we have placed strategically throughout Winyah Bay. Since our sharks are all migratory and not permanent residents, and since the battery life of acoustic tags is as long as 10 years, we also rely on detections by receivers placed by others at locations along the entire Atlantic and Gulf coasts, which are periodically reported to us. Similarly, we report detections of animals tagged by others to them. Drawbacks to this method include the cost (about $300 per tag and >$1,500 per receiver) and the detection range, which does not typically exceed 400 m (1,300 ft) and varies with environmental factors.
Depending on the project, we also collect and analyze blood samples, and take fin clips for future DNA analysis and tissue plugs for analysis of stable isotope ratios. This last method assumes “you are what you eat” and is useful for understanding a species’ diet and trophic (feeding) ecology.
For a project examining shark behavior, we maintained sharks in outdoor pens and used videography. Back in the lab, we have microscopically looked at plastics in sharks and organs like hearts and rectal glands. Finally, we use a variety of statistical approaches and software packages to analyze our data. Methods still on the drawing board include satellite tagging and using drones for aerial surveys.
Our primary research site is Winyah Bay which is a partially mixed estuary whose shark fauna had not been systematically and intensively studied before we initiated the CCU Shark Project. Winyah Bay is one of the most wondrous places on the planet, a gem unknown to most residents of the Grand Strand, and one that is home to >10 species of sharks.
In addition to Winyah Bay, we have also conducted studies in other South Carolina ecosystems, including North Inlet, Murrells Inlet, North Santee, and Port Royal Sound, and as far away as the Florida Keys and Bimini, Bahamas.
We measure, tag, take blood other tissue samples, and quickly release the sharks. If the sharks are in good shape, we will take a few minutes to educate students about them, and teach students how to handle a shark."
Former CCU graduate student, Jessie Wingar working on a university research cruise as part of Abel’s Biology of Sharks course.
Q: What scientific questions are you addressing?
The CCU Shark Project began as a small-scale, episodic, estuarine survey with the dual purpose of teaching students about shark research and to understand ecology and physiology of the sharks found in three Northeast South Carolina estuaries. The initial research goals of the project were to: 1) identify sharks inhabiting these systems; 2) describe shark population structure, distribution, and migrations and their environmental influences; 3) determine whether these systems serve as nurseries; and 4) identify human impacts. We have also studied the physiology and ecology of sharks in other areas. Some of our projects conducted by me, my graduate and undergraduate students, and other collaborators, include:
- Survey of the shark fauna in two South Carolina estuaries and the impact of salinity structure.
- Seasonal occurrence, relative abundance, and migratory movements of juvenile Sandbar Sharks, Carcharhinus plumbeus, in Winyah Bay, S.C.
- Osmoregulatory adaptations of deep-sea sharks and whether they represent a paradigm shift.
- Osmoregulation and salinity preference in juvenile Sandbar Sharks (Carcharhinus plumbeus) in Winyah Bay, S.C.
- Microplastics in the digestive system of the Atlantic Sharpnose Shark (Rhizoprionodon terraenovae) in Winyah Bay, S.C.
- Home range, residency, diel movement and tidal patterns of Bull Sharks (Carcharhinus leucas) in Winyah Bay, S.C.
- Residency and movement patterns of Blacktip Sharks, Carcharhinus limbatus, in the North Santee estuary.
- Demographics and habitat partitioning of the shark fauna of Port Royal Sound, S.C.
- Determining the relative abundance and habitat preference of elasmobranchs in North Inlet estuary, S.C.
- Blacktip shark Carcharhinus limbatus presence at fishing piers in S.C.: association and environmental drivers.
- The effects of familiarity on the social interactions of juvenile Lemon Sharks, Negaprion brevirostris.
- Analysis of permanent magnets as elasmobranch bycatch reduction devices in hook-and-line and longline trials.
- Response of juvenile Lemon Sharks, Negaprion brevirostris, to a magnetic barrier simulating a beach net.
- Responses of the Southern Stingray (Dasyatis americana) and the Nurse Shark (Ginglymostoma cirratum) to permanent magnets.
- Unique rectal gland morphology and plasma chemistry of the deep-sea shark family Hexanchidae.
- Habitat selection and demographics of Sandbar Sharks in Winyah Bay, S.C.
- Distribution and movements of neonate Atlantic Sharpnose Sharks, Rhizoprionodon terraenovae, in a S.C. estuary ocean waters.
- Comparison of the elasmobranch fauna in two South Carolina estuaries differing in the degree of human impact.
- Habitat utilization by multiple coastal shark species in a Southeastern salt marsh nursery system.
- Comparison of the hearts of deep-sea and shallow-water sharks
Dan Abel doing research at Winyah Bay, Georgetown, S.C., in 2002.
CCU students observing actively-feeding Caribbean Reef Sharks in Bimini, Bahamas.
Q: What are the significant findings of your research?
The following is a brief list of some of our more salient findings:
- The number (concentration) of microplastics in Atlantic Sharpnose Sharks from Winyah Bay was among the highest found in sharks.
- Juvenile Sandbar Sharks spending their summer and early fall in Winyah Bay migrated south to Florida, a previously undocumented route.
- Juvenile Sandbar Sharks in Winyah Bay exhibited similar osmoregulatory adaptations to those of Bull Sharks (the first time this has been documented).
- The rectal glands of Hexanchid (sixgill) sharks exhibited a unique morphology indicative of their phylogenetic age more so than their deep-sea habitat.
- Extensive longline and gill net surveys of Murrells Inlet revealed a highly depauperate shark fauna, compared to that of North Inlet.
- Winyah Bay and other local estuarine ecosystems represent important habitat and nursery grounds for some shark species.
- Juvenile Lemon Sharks are capable of recognizing each other, and prefer familiars to strangers.
- Salinity strongly influences the distribution of all species of sharks and rays in Winyah Bay.
- Some mature Blacktip Sharks associate with specific piers, likely attracted by increased foraging opportunities afforded by the pier structure, or by attraction from angler discards or bait. This is the first scientific study of the association of sharks with piers.
- Strong permanent magnets repel some species of sharks and may have utility as personal shark deterrents or to decrease shark and ray bycatch in beach nets and commercial longlines.
Q: What directions might the shark program take in the future?
The shark program has hidden benefits, and we will continue as long as CCU supports us as it has during the last 25 years. First, we teach students about conducting research on the water. Surprisingly, some marine science majors have graduated with experience from only one or, sometimes, no cruises. I’d like to increase that number to four or five cruises for marine science majors. Second, the shark cruises embody the coastal in Coastal Carolina University. We teach participants about marine environmental issues and sustainability, and help them develop the sense of place that they can never achieve in the classroom. Also, although logistically difficult, wouldn’t it be great to take every CCU graduate student, undergraduate student, faculty member, staff member, and administrator on a shark research cruise? An educator’s dream, if an administrative nightmare.
Research-wise, we intend to push forward on some of the questions that have not been fully or satisfactorily answered on understanding the ecology of sharks in Winyah Bay and other coastal ecosystems in Northeast South Carolina. Currently, we are looking at the accumulation of micro-plastics starting with neonate (newborn) Atlantic Sharpnose Sharks born locally and documenting how much microplastic they acquire during their six-month or more local residencies. We may also undertake a study of sharks along beaches, research that may strike a nerve locally but which is crying to be conducted.
Finally, Dean Grubbs of Florida State University and I have co-authored, “Shark Biology and Conservation for Enthusiasts, Educators, and Students,” to be published by Johns Hopkins Univerity in 2020; and one on Apex Predators, with co-authors Robert Johnson and Sharon Gillman, behind that. Plus, there are several manuscripts on our research that need to be published. Then, there is the second edition of “Shark Biology and Conservation.”
We teach participants about marine environmental issues and sustainability, and help them develop the sense of place that they can never achieve in the classroom."
Former CCU graduate students Kelsey Martin (top) and Carolina Collatos (bottom) removing hooks from a large southern stingray (top) and a juvenile sandbar shark (bottom).
Q: Do you have any suggestions for students wanting to study sharks?
(1) Take MSCI 473/473L, Biology of Sharks.
The course is offered three different ways (take only one of them).
(A) Take the course in fall semester.
There is a maximum of 20 seats in the fall offering. The class meets twice weekly. The lab meets as a traditional lab only two or three times; the remaining lab time is spent on five or more shark research and student training cruises offered at various times.
(B) Attend the Maymester study abroad trip.
Maximum enrollment is 16. The course includes six days at the Bimini Biological Field Station in the Bahamas, followed by field trips during the two weeks following the trip. There is a substantial cost associated with this option. For more information go to coastal.edu/educationabroad/ step2researchprograms/ faculty-ledprograms/ maymesterbiologyofsharksinbimini (C) Take the *NEW* course in the Summer I term. Maximum enrollment is 14. The class typically meets M–Th for five weeks in Georgetown. Labs will consist mostly of cruises but will include traditional labs.
(2) Volunteer on our cruises.
Please either see me or email CCU Shark Research at ccusharkresearch@gmail. com to get on our mailing list. Cruises occur at all hours of the day during all days of the week. Most cruises are scheduled for summer and fall, but we episodically sample in the winter. Cruises are not limited to marine science majors; we gladly take any members of the CCU community.
(3) Complete an internship.
There are now numerous domestic and international internship opportunities that enable you to work closely with sharks. Either see me or contact Robert Bulsza, director of internships and service learning (Career Services Center, Lib Jackson Student Union A203B).
(4) Complete other courses.
If you are considering working with sharks for a career, one of the best strategies is to become an exceptional scientist focusing not on sharks, but rather specializing in a field in which the principles and skills you learn could be transferred to the study of sharks. These include ecology, taxonomy, physiology, molecular biology, conservation biology, behavior, fisheries, etc.