By: Paris Reynosa
When you hear the word “Oyster” what do you think of? If you’re the average person, perhaps pearls or the aphrodisiac. However, scientists, fishermen, and policymakers, today may hear an answer to some of North Carolina’s economic and environmental issues.
North Carolina is proud to be home to two reef systems: the Outer Shelf Reefs and Lophelia Coral Banks. These reefs and their surroundings have served as nurseries[1] for a variety of marine life. Yet, an increase in coastal erosion, development, and water pollution, has threatened many of our coastal species. Commercial fish[2], such as flounder, black bass, and blue crab, face threats as the seagrasses they rely on are killed by pollutants. The drop in plant life has created a risk of low-oxygen zones in the Pamlico and Albemarle Sounds leading to fish loss in these areas. But that’s where our favorite bivalve comes in…
Eastern oysters are natively found in N.C.’s deepwater reefs in the Pamlico Sound, patch reefs in intertidal waters, and fringing reefs in salt marshes lining estuarine shores[3]. Here are some of the ways the Eastern Oyster plays a vital role in our ecosystem:
Habitat and Breeding Space: Eastern Oysters are keystone species and ecosystem engineers. As a defense mechanism, they grow in cemented clusters forming reefs in sub-tidal and intertidal zones. These clusters provide structure for other organisms to use as shelter, foraging areas, and breeding grounds. Approximately 75% of the United States’ commercial fish and shellfish depend on estuaries at some point in their life.[4]
Shoreline Erosion and Buffering: The structure of oyster reefs helps break up wave impact, buffers land from storms, and prevents shoreline erosion. Through filter feeding oysters deposit sediment which builds surrounding land. By breaking the impact of waves, oysters allow the inland growth of seagrasses, marsh grasses, and other less wave-tolerant species[5].
Filter Feeding & Denitrification: As filter feeders, oysters filter suspended particles to use as energy, collecting and depositing undesired particles as sediment. Consequently, they decrease particle suspension and turbidity, allowing more light to reach benthic producers[6]. Through sediment deposition, oysters also bury nitrates which would otherwise lead to eutrophication. This is vital for N.C. as the second leading state in the U.S.’s swine industry[7], infamous for nutrient runoff.
Despite these benefits, their population has drastically dipped by 85% in the past 150 years due to habitat loss, natural disasters, and overharvesting[8]. During the Reconstruction, oyster farming became increasingly popular for money. However, poor harvest practices using iron dredging destroyed populations in Maryland and Virginia by the 1880s. This turned an eye south to North Carolina’s oyster reserves. The desire for oysters became so intense that in 1891, North Carolina declared an “Oyster War”[9]. This led to a series of acts prohibiting the sale and export of oysters outside of N.C., causing the decline of armed pirates lurking on the coast due to the oyster shortage.
Although newer policies have decreased the intensity of dredging and overfishing, the drivers have persisted as the top reasons for the Eastern Oyster’s demise. Dredging destroys reefs by scraping structures off of the seafloor and burying remaining reefs. Depending on burial depth there are possible increases in mortality[10]. When paired with hypoxia, disturbances via dredging can inhibit oyster reef growth[11]. Although historically used for harvesting, dredging is becoming increasingly popular for land development[12]. Due to unsuccessful oyster bed replenishment, there’s little recovery after dredging. Overharvesting of oysters has been limited by state harvest policies but still negatively affects oyster populations. It not only extracts an unsustainable amount of oysters but removes shells that are often used as substrates for larvae development.
N.C. Conservation and Restoration Options
While there are cultch planting programs and living shoreline developments, these two restoration methods could be improved. Changes in dredging and harvesting practices could also aid reef replenishment.
Cultch Planting & Living Shorelines: Cultch planting includes placing hard substrates such as limestone or oyster shells in marshes and sounds. Occasionally, larvae are already on this substrate. These cultches are often grouped along shores to create living shorelines. Before reef restoration is implemented, it’s advised that factors such as salinity, pollution, urbanization, sediment conditions, currents, and wave action, are analyzed since they heavily influence the functional and long-term success of restored reef systems. There is current cultch and living shoreline research and projects underway by organizations such as NOAA, NCSG, and NCCF. However, there are few studies published on the effects of substrate composition and structure on larval recruitment and long-term reef growth. Although, this is most likely due to the recency of living shoreline development. So far, substrate methods include granite, shell, concrete, and marl while some living shoreline methods include oyster shell bags, rock sills, and reef balls[13]. An increase in better-informed cultch plantings and living shoreline projects and long-term monitoring of these areas’ success may hold the key to local restoration.
Dredging and Harvesting Policies: Due to mechanical dredging’s damage, alternative forms of sediment management might mitigate the effects of development. The environmental effects of alternatives such as sand traps and pile groynes should be further studied as they could offer safer options[14]. Additionally, the dredging permits that currently exist to avoid extensive habitat destruction and water pollution should have stricter criteria. This could be achieved by imposing further restrictions under legislation such as N.C.’s Sedimentation Pollution Control Act[15]. The environmental impacts of the area dredged as well as mitigation plans should be thoroughly assessed. In addition to the continual reinforcement of current harvest limits, harvest zone rotations should be looked into for the Eastern Oyster as they have proven efficient in other aquaculture cases [16]. If zone rotations were implemented, extensive overharvesting could be prevented by giving inactive harvest zones time to replenish population numbers.
If we can come together to improve harvesting and dredging practices while increasing living shoreline and cultch research and action, we could not only save the Eastern Oyster but all of the biodiversity it supports.
Citations
[1] Ward, H. (n.d.). SEA SCIENCE: Getting to Know North Carolina’s Natural Reefs. Coastwatch. https://ncseagrant.ncsu.edu/coastwatch/previous-issues/2007-2/autumn-2007/sea-science-getting-to-know-north-carolinas-natural-reefs/
[2] Gona, A. (2016, September 21). Estuaries: Protection and Restoration. Coastal Review. https://coastalreview.org/2016/09/estuaries-protection-restoration/
[3] Oysters. (2024, February 8). North Carolina Coastal Federation. https://www.nccoast.org/oysters/#:~:text=Oyster%20habitat%20in%20North%20Carolina
[4] Coen, L.D., Luckenbach, M.W., & Breitburg, D. (1999). The role of oyster reefs as essential fish habitat: a review of current knowledge and some new perspectives.
[5] Meyer, D. L., Townsend, E. C., & Thayer, G. W. (1997). Stabilization and erosion control value of oyster cultch for intertidal marsh. Restoration Ecology, 5(1), 93–99. doi:10.1046/j.1526-100x.1997.09710.x
[6] Newell, R. I., & Koch, E. W. (2004). Modeling Seagrass density and distribution in response to changes in turbidity stemming from bivalve filtration and seagrass sediment stabilization. Estuaries, 27(5), 793–806. doi:10.1007/bf02912041
[7] Zering, K. (n.d.). Retrieved from https://cals.ncsu.edu/are-extension/animal-agriculture/swine/
[8] Allen, J. (2021, April 27). Efforts On to Rebuild NC’s Oyster Population. Coastal Review. https://coastalreview.org/2021/04/efforts-on-to-rebuild-ncs-oyster-population/
[9] Stevenson, G. (2006). Oyster War | NCpedia. Www.ncpedia.org.
[10] Colden, A., & Lipcius, R. (2015). Lethal and sublethal effects of sediment burial on the eastern Oyster Crassostrea virginica. Marine Ecology Progress Series, 527, 105–117. doi:10.3354/meps11244
[11] Lenihan, H. S., & Peterson, C. H. (1998). How habitat degradation through fishery disturbance enhances impacts of hypoxia on oyster reefs. Ecological Applications, 8(1), 128–140. doi:10.1890/1051-0761(1998)008[0128:hhdtfd]2.0.co;2
[12] Deason, G., Seekamp, E., & Barbieri, C. (2014). Perceived impacts of climate change, coastal development and policy on oyster harvesting in the southeastern United States. Marine Policy, 50, 142–150. doi:10.1016/j.marpol.2014.05.008
[13] CDEEP (2023). Living Shorelines Techniques. Living Shorelines Conneticut Department of Energy & Environmental Protection.
[14] Bianchini, A., Cento, F., Guzzini, A., Pellegrini, M., & Saccani, C. (2019). Sediment management in coastal infrastructures: Techno-Economic and Environmental Impact Assessment of alternative technologies to dredging. Journal of Environmental Management, 248, 109332. doi:10.1016/j.jenvman.2019.109332
[15] Erosion and Sediment Control Laws and Rules | NC DEQ. (n.d.). Www.deq.nc.gov. https://www.deq.nc.gov/about/divisions/energy-mineral-and-land-resources/erosion-and-sediment-control/erosion-and-sediment-control-laws-and-rules
[16] Plagányi, É. E., Skewes, T., Murphy, N., Pascual, R., & Fischer, M. (2015). Crop rotations in the sea: Increasing returns and reducing risk of collapse in sea cucumber fisheries. Proceedings of the National Academy of Sciences, 112(21), 6760–6765. doi:10.1073/pnas.1406689112
[1] Ward, H., SEA SCIENCE: Getting to Know North Carolina’s Natural Reefs. Coastwatch. (n.d.).
[2] Gona, A., Estuaries: Protection and Restoration. Coastal Review. (2016, September 21).
[3] Oysters. North Carolina Coastal Federation. (2024, February 8)
[4] Coen, L.D., Luckenbach, M.W., & Breitburg, D., The role of oyster reefs as essential fish habitat: a review of current knowledge and some new perspectives. (1999).
[5] Meyer, D. L., Townsend, E. C., & Thayer, G. W., Stabilization and erosion control value of oyster cultch for intertidal marsh. Restoration Ecology, (1997).
[6] Newell, R. I., & Koch, E. W., Modeling Seagrass density and distribution in response to changes in turbidity stemming from bivalve filtration and seagrass sediment stabilization. Estuaries, (2004).
[7] Zering, K., Swine (n.d.).
[8] Allen, J., Efforts On to Rebuild NC’s Oyster Population. (2021, April 27)
[9] Stevenson, G. Oyster War (2006)
[10] Colden, A., & Lipcius, R. Lethal and sublethal effects of sediment burial on the eastern Oyster Crassostrea virginica. Marine Ecology Progress Series (2015)
[11] Lenihan, H. S., & Peterson, C. H. How habitat degradation through fishery disturbance enhances impacts of hypoxia on oyster reefs. Ecological Applications, (1998)
[12] Deason, G., Seekamp, E., & Barbieri, C.. Perceived impacts of climate change, coastal development and policy on oyster harvesting in the southeastern United States. Marine Policy, (2014)
[13] CDEEP Living Shorelines Techniques. Living Shorelines Conneticut Department of Energy & Environmental Protection. (2023).
[14] Bianchini, A., Cento, F., Guzzini, A., Pellegrini, M., & Saccani, C., Sediment management in coastal infrastructures: Techno-Economic and Environmental Impact Assessment of alternative technologies to dredging. Journal of Environmental Management, (2019).
[15] Erosion and Sediment Control Laws and Rules | NC DEQ. (n.d.)
[16] Plagányi, É. E., Skewes, T., Murphy, N., Pascual, R., & Fischer, M. Crop rotations in the sea: Increasing returns and reducing risk of collapse in sea cucumber fisheries. (2015)
Super cool post, Paris! This issue of over-harvesting oysters is a difficult one — it’s challenging to strike a balance between conservation and the economic opportunity attached to the industry. I thought your suggested solutions were really interesting. I’d want to see more information on how different substrates used in shoreline development compare to each other and if certain species and larvae types respond better to oyster shells or certain substrates. Getting this information would probably just take time, which might be a luxury that the oysters don’t have.
Maybe in the meantime, work similar to that of the Duke Aquafarm could be encouraged and given more funding. This would ideally allow them to better understand oyster growth patterns, genetics, and responses to different sedimentary conditions (1).
Sources:
https://nicholas.duke.edu/news/duke-aquafarm-gives-students-experiential-oyster-farming-experience
Hi Paris! I really enjoyed reading your blog. Coming from the Eastern Shore of Maryland, I am familiar with how important oysters are to coastal communities and ecosystems! The Chesapeake Bay has been desperately trying to increase oyster populations for decades, since they have been depleted by overfishing and decreased Bay health. Growing up, my family would raise oyster spat for the Chesapeake Bay Foundation and then help them get released into oyster sanctuary reefs. There are also all kinds of initiatives to try to raise education on the importance of oysters and how to increase their populations. By 2025, the Chesapeake Oyster Alliance has a goal to add 10 billion oysters to the Bay, and as of January 2023, they had added over half of this goal. However, though there are many good initiatives in place, there is still much more work to be done to help oyster populations. I agree with your idea of implementing more successful living shorelines could be a step in the right direction to local restoration. Restoring and protecting oyster populations is such a critical issue, and without these populations, communities, economies, and entire ecosystems would suffer. Though this is such an important issue, there is hardly any federal action to help oyster communities, which is another issue that needs to see change in order to save these populations.
https://www.cbf.org/about-cbf/our-mission/restore/oyster-restoration/index.html
https://www.cbf.org/blogs/save-the-bay/2023/01/oysters-on-the-rise.html#:~:text=COA%20recorded%20its%204.47%2Dbillionth,to%20the%20Bay%20by%202025.
Hey Paris, I found your post about the role of oysters in North Carolina’s ecosystem and economy both interesting and alarming. The way you outlined the multiple benefits of oysters, from creating habitats to reducing shoreline erosion, really highlights how crucial they are beyond just being a delicious seafood. The historical context you provided about oyster harvesting and their decline due to dredging and overharvesting paints a great picture of the challenges we face. It’s disheartening to see such a valuable resource struggle due to human activities. Your discussion on the potential improvements in cultch planting and living shoreline projects was particularly interesting. It seems like these efforts could play an important part in not only restoring oyster populations but also improving the overall health of our marine ecosystems!
Hey Paris! You’re super knowledgeable about oysters, have you done research with them before? I know that the Duke Marine Lab is in the middle of an oyster reef, you should totally consider doing independent research there.
I loved your analysis and explanation of the different oyster ecosystems in North Carolina, I feel caught up to how prominent of a species they are on the shores of N.C. Their importance as a keystone species is often overlooked due to their simple nature and lack of mobility: their water filtration and habitat creation for other species is incredibly important for other organisms. I appreciated your note about dredging, I have seen how it is undertaken, and I personally think it is appalling as to how it is even allowed because it looks so damaging. Especially with the high currents of the Atlantic Ocean degrading and shrinking N.C. coastlines, I agree that stricter standards should be implemented in order to protect shallow oceanic ecosystems.