**1. Introduction**

Coastal areas are home to a wealth of economic and natural resources and are the most developed areas in the nation with continuous increase in human population. Over 50% of the nation's population resides in 17% of the U.S. coastal areas. In light of these numbers, it is critical that consideration be given to the impact humans have on these coastal ecosystems and to the methods which are currently being utilized to enhance and restore these coastal habitats. There are various ways people use coastal areas for their needs. Shellfish aquaculture is one of the many activities people conduct.

and sediment erosion resulting from several decades of poor land use practices including housing development, agriculture and sustained nutrient input from within the surrounding watershed [1]. The cumulative impacts of these effluents from anthropogenic activities has degraded water quality and reduced the diversity and abundance of various species of aquatic life including fishes, invertebrates and submerged aquatic vegetation [2]. As a keystone species in estuarine bays, oysters provide important ecological services in these systems by filtering suspended particulates from the water column, increasing water clarity, and removing nutrients from eutrophic waters [3, 4]. Oyster reefs also serve as a valuable component of estuarine ecosystems, offering unique habitats for many ecologically, economically, and recreationally important species [2]. The bay degradation has led to the dramatic decline of the local oyster

Are Aquaculture Practices Sustaining Our Goal to Restore Oysters (*Crassostrea virginica*)?

http://dx.doi.org/10.5772/intechopen.78989

35

In response to the plummeting populations, 'oyster gardening' programs have taken root throughout the estuarine ecosystems of the Mid-Atlantic, including Delaware Inland Bays (*see* **Figure 1a**), in an effort to restore the native oysters for their ecological and commercial contribution to the health and viability of coastal estuaries. Many community-based estuary programs have involved volunteers to help rear larval oysters into healthy adults for reef restoration and it is no different in Delaware Inland Bays [5, 9, 10]. Volunteers living in the local communities surrounding the watershed in the Delaware Inland Bays place floating baskets of oysters at the ends of their docks to allow the filter-feeders a safe haven to grow from small, young spat into thriving adult oysters (*see* pictures in **Figure 1b**). Community members throughout southern Delaware are being given the unique opportunity to observe first hand many of the important ecological services provided by oysters and learn about the

With a shoreline of approximately 418 km, no part of Delaware more than 13 km from tidal waters, with Delaware Inland Bay consisting of three shallow coastal Bays: Rehoboth, Indian River, and Little Assawoman Bays. The combined surface water area of the three bays covers 83 square km with an average depth of 1.2 m. The Delaware Inland Bays (DIB) supports a small commercial hard clam and blue crab fishery along with weakfish, spot, bluefish, and Atlantic menhaden representing the majority of the commercial finfish catch in the Delaware Inland Bays and a variety of other commercially and environmentally important aquatic

Associated problems in those bays are similar to other Mid-Atlantic estuaries including eutrophication, high turbidity, sedimentation, periodic hypoxic/anoxic conditions, annual fish kills, low species diversity, and physical disturbances due to anthropogenic activities especially in the man-made canal systems. According to Delaware Inland Bays Estuary Program Report [11] and Chaillou et al. [1], approximately 80% of freshwater flow is from groundwater and the sandy, permeable soils of the watershed have led to widespread contamination of groundwater by nitrates in Delaware Inland Bays. Flushing rates may vary widely among the three bay areas, being as low as 1–7 days for Little Assawoman while those for Rehoboth and

Delaware Center for the Inland Bays Report [12] stated agriculture as the largest use of land (32%) followed by developed/developing lands (22%), forested lands (17%) and wetlands and waters (16% and 12%) with significant loss of forest lands recorded in the watershed between

Indian River Bays may be as high as 80 and 100 days, respectively.

*Crassostrea virginica* populations since the late 1800s [4–7].

local watersheds.

species [64].

In this chapter, we compare and contrast the health and status of the Eastern oyster, *Crassostrea virginica*, in two east coast estuaries: the Delaware Inland Bays, Delaware and Apalachicola Bay, Florida. Many ecological services which are provided by oysters, such as their filtration, benthic and pelagic coupling, and habitat forming characteristics, have been extensively studied and discussed. Oysters increase water clarity and quality by filtering sediments and algae, and removing nutrients such as nitrogen and phosphorous. The Eastern oyster was once a fixture of the local economies on the east coast however, combined effects from over harvesting, habitat destruction, and diseases such as Dermo and MSX have caused oyster populations to decline dramatically. Along with this decline in oyster populations, coastal lagoons in east coasts of the United States have been experiencing rapid development within the coastal watershed increasing eutrophication events. The once abundant oysters filtered algae and sediments, removed phosphorus and nitrogen, and played a vital role in the ecosystem that could help to counteract the increasing pressure on the watersheds. Many regional economies in the United States of which the harvest of Eastern oysters was a major component, struggled with the collapsed fishery.

In response to these issues, oyster aquaculture has grown and is now a major part of the working waterfront where traditional wild oyster populations used to thrive. In recent years, farm-raised oysters have become a more sustainable operation than commercial fishing. Oyster aquaculture has benefits beyond supporting human economies and diets. Oyster aquaculture can provide many of the same ecological services as oyster reefs, which are a valuable component of estuaries worldwide, serving as a unique habitat for many ecologically and economically important species. Research focusing on the ecological effects of oysters raised with commercial aquaculture equipment is becoming more prolific as the industry moves away from a wild harvest fishery to a cultivated product. However, there is a critical need to better understand the dynamics of local waters to enhance potential fisheries for both estuaries. The oyster fishery may be recouped if the demand for oysters is supplied with oysters from aquaculture operations. Our primary goal in this chapter is to increase awareness about the potential benefits and some of the challenges facing the increased presence of aquaculture in these estuary systems.
