Oyster Ecology in the Field
A day in the field learning about the ecological roles of oysters in estuaries at North Inlet Estuary, South Carolina
Welcome to the North Inlet Estuary in South Carolina!
This guided tour serves as an introduction to the study of oysters, the much-beloved reef-forming bivalves that line creeks and bays throughout the southeastern US. We will also highlight some of the different ecological roles played by oysters and explore a few of the ways scientists collect them for study.
Pack your sunscreen, field lunch and waders, because you'll be spending the day exploring the field while learning from real marine scientists! Be sure to click through the videos and images in the media gallery at each location to get the full experience of the virtual field. Double-click on the images to get a fullscreen view.
North Inlet Estuary, Hobcaw Barony, and the Baruch Marine Field Laboratory
North Inlet estuary is located on the South Carolina coast and sits on the edge of Hobcaw Barony , a privately owned research reserve nearly 16,000 acres large. North Inlet estuary and Hobcaw Barony are also home to the University of South Carolina’s Baruch Marine Field Laboratory and the North-Inlet Winyah Bay National Estuarine Research Reserve .
Salt marshes and tidal creeks make up most of North Inlet estuary. A salt marsh is a productive coastal wetland ecosystem that in the southeastern US, is dominated by single plant, smooth cordgrass (Spartina/Sporobolus alterniflora). Various intertidal (shallow) and subtidal (deep) creeks wind their way through the salt marshes of North Inlet estuary. These creeks remain quite salty throughout the year, because the estuary is heavily influenced by ocean tides.
What Are Oysters? Where Do They Occur?
Before we go into the field, it is important to understand what oysters are, and why we study them.
At North Inlet Estuary, there is one species of oyster, Crassostrea virginica, the eastern oyster. This is the dominant oyster species in estuaries along the coast from Maine to Florida, and throughout the northern Gulf of Mexico.
Oysters are bivalve mollusks, meaning they have a soft body and two hard external shells joined by a hinge. They are benthic animals that prefer hard substrate – they attach to and live on submerged hard surfaces throughout most of their lives
They have a complex life cycle – though they are sessile (immobile) for most of their life, they spend several weeks in the water column in their early (larval) life stages
Also - oysters are delicious! They are harvested throughout the world for food.
Click here to see an example of where oysters occur in relation to the tidal stages in the North Inlet Estuary.
What Are Oyster Reefs?
Oysters live in groups – preferred settlement locations are clean, hard surfaces, which often means other oysters. Over time, oyster “clumps” grow into reefs.
In temperate systems like North Inlet Estuary, they function much like coral reefs, unique habitats full of nooks and crannies (interstitial space).
Come along for a walk in the tidal creeks of North Inlet Estuary to see the many various types of reefs found within the estuary.
Ecological Roles of Oysters and Oyster Reefs
Next we'll explore how oysters promote multiple ecosystem services, or ecological benefits to humans, including improved water quality, shoreline protection, and fisheries productivity.
First, they are filter feeders - removing particles from the water column. Second, they serve as a hard substrate and trap nutrient-rich sediments to promote nutrient cycling. By trapping sediment, they help stabilize areas where they occur. Also, the hard structure and complex architecture of oyster reefs means they serve as habitat and feeding ground for numerous other species in estuary such as fishes and crabs.
Click here to watch a time-lapse video of oysters filtering water, and here to see the many ways oysters are used as habitat.
Investigating the Many Roles of Oysters
Ecologists use a number of different techniques to assess oysters, reefs, and the services they provide
They collect information regarding populations of oysters, including their abundance and growth. Many scientists employ quadrat-based sampling of reefs. Click here for an example of quadrat sampling.
The size of an oyster can give an indication of its age, and can be used to help estimate growth over time. It might seem like an easy question, but how does one measure and oyster, exactly? Click here for a video demonstration!
To assess the value of oyster reefs as habitat for other organisms, scientists sometimes use habitat trays , which are embedded into a reef for a set amount of time. Over time, animals move into the trays, providing a window into who is using the oyster reef and when, and also how abundant they are.
Deeper Discoveries in Oysters Ecology
We've spent the day with scientists in the field and got to see some lab work, too! Are you interested in seeing the data you helped collect? Click here for access to the data and additional resources to dive deeper into oyster ecology.
Acknowledgments
This guided tour was developed by the Baruch Marine Field Laboratory at University of South Carolina, and University of Georgia Marine Institute at Sapelo Island . This collaboration was funded by the National Science Foundation ( award #2037372 ) to develop virtual products that support marine and estuarine field science and mitigate education disruptions from COVID-19.