**4. Where shared challenges meet shared solutions?**

**Figure 9.** Apalachicola Bay relies on freshwater input from the Apalachicola River to maintain ecosystem health and to

Bay was exceptionally high in 2012 [39]. In January 2018, the Supreme Court of the United States heard arguments concerning the Alabama-Georgia-Florida water war. A ruling has not been issued at this time. Florida is seeking a water-sharing pact such that Georgia's usage of the ACF

In addition to decreased freshwater inflow, climate change models predict a north Florida sea level rise of up to 15 inches by the end of the century. Scientists speculate that this vertical rise may push the shoreline 70–250 feet inland in low-lying coastal areas (*see* **Figure 8**). According to a one report, this would submerge 61% of salt marshes and three quarters of the tidal fresh

In August 2013, NOAA declared the Apalachicola Bay oyster fishery a disaster, caused by a long and excessive drought during the 2012–2013 season. Due to those events, Florida west coast oyster landings dropped 60% and revenue declined 44% [85]. The Deepwater Horizon Oil Spill did not impact Apalachicola Bay oysters significantly. Oysters tested by the University of Florida [39] were below instrumental detection for oil spill contaminants, polycyclic aromatic hydrocarbons (PAHs). According to research in the same report, a high percentage of bay oyster shells are parasitized by boring clams, sponges, polychaete worms or other organisms. In addition to a decrease in shellfish growth and productivity, shell deformity also detracts from shell integrity and may therefore affect the economic value of product. Dermo disease is present in Apalachicola Bay oysters, but apparently, its severity is less than in other bays along the East Coast, such as the Chesapeake Bay [41]. The UFL researchers

In an attempt to save a struggling industry, Florida's leaders have approved oyster and clam aquaculture leases in Wakulla County and in Franklin County (*see picture in* **Figure 9**). In April 2018, Florida's governor and his cabinet are looking to approve expanding current

headwaters does not create adverse downstream effects for Apalachicola Bay fisheries.

water marshes [40].

46 Aquaculture - Plants and Invertebrates

support a productive shellfish fishery. *Map from State of Florida, updated by Stacy Smith.*

report that more than 90% of tested oysters are positive for the parasite.

As stated by Rossi-Snook et al. [24] "an integral aspect of oyster gardening programs that cannot go unmentioned is the development of a sense of environmental stewardship among community members. In these programs, professional scientists and volunteers are working together to conserve both an ecosystem and a culture; by reintegrating oysters back into the bays, natural recruitment and proliferation is possible, eventually allowing for the safe and ecologically-sound harvest of oysters and other ecologically important macrofauna to redevelop within the community."

Ecosystem engineers, as described in many environmental books and articles, are organisms that can dramatically change the environment and essentially create ecosystems. Jones et al. [42] discussed differences between allogenic and autogenic ecosystem engineers. He stated oysters fall in to both categories: allogenic because they "change the environment by transforming living or non-living materials from one physical state to another, via mechanical or other means," and autogenic because they "change the environment via their own physical structures (i.e. living and dead tissue) as they grow and become larger, their tissues create habitat for other organisms to live in."

Although, *Crassostrea virginica* can tolerate a wide range of salinity, temperature, turbidity, and oxygen levels, Kennedy [6] discussed how water depth and salinity affect oyster populations and their associated fauna. Oysters generally occur in areas with the annual temperature range between −2 to 36°C except for the oysters in Gulf of Mexico which can survive intertidal temperatures between 44 and 49.5°C for over 3 hours. Larger established populations are found at salinities ranging from 5 to 40 ppt. Nevertheless, adult oysters have the ability to survive even in fresh water for short time durations [6]. When oysters are located in areas of an estuary with less salinity, they have slower growth rates. This is primarily due to a lack of food availability. In addition, because "drills, starfish, and boring sponges cannot stand the reduced salinities that prevail" in areas farther up in estuaries, oysters are able to have a higher rate of survivorship in these zones ([43], cited by [44]).

Indeed, bivalves can affect a shift in the phytoplankton community. Many authors have suggested that bivalves exert a "top-down" control of phytoplankton dynamics [51–54]. Some have stated in certain instances there exists a synergistic feedback. Oysters considerably advance the timing of nutrient recycling rates, allowing indulgence consumption and fast growth of some algal species [55, 56]. Through continuous filtering activities of the oysters, the phytoplankton community is shifted from older lag phase cells to younger cells in a logarithmic growth phase. Reduced competition causes the phytoplankton community to shift to faster growing algal species that are able to take advantage of the increased light

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

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

49

*Crassostrea virginica* are bivalve suspension-feeder organisms that are native to the Delaware Inland Bays and Apalachicola Bay areas. Bivalve suspension feeders have been shown to serve an important biogeochemical role in coastal ecosystems because N and P from the water column are transferred to the sediments in their biodeposits [3]. This means that the filtration of the oysters can be shown to remove nitrogen from an aquatic ecosystem. Although the benefits of physical oyster structure may be significant, the benefits from oysters' ecological function are under-appreciated [58]. Although many studies have been done to focus on various effects of oyster ecology on lower trophic levels, resident species, and water quality, very few studies have yet conclusively demonstrated net benefits to higher

One of few studies showed where oysters enrich the surrounding benthos with their biodeposits and dissolved nutrients increases meio- and macrofauna species assemblage in their study [46]. Also observed by Bahr and Lanier [46], many oyster reef residents feed upon these lower trophic levels and find aid in the unique niches created by the oysters. Polychaete were collected from the sediments under the oyster gears, 1 meter away from the gears and 5 meters away from the gear in the Delaware Inland Bays. Polychaete survey results during the warmer months indicate the highest abundance of polychaetes were found at the Little Assawoman site and the lowest abundance of polychaetes in Rehoboth Bay. The results of the benthic community assessment indicate that there was no significant impact to Polychaete abundance or species richness from the oysters and aquaculture gear. Little Assawoman Bay had higher abundance and species richness than other two bays [59]. Benthic community assessments are often used to evaluate the health of an ecosystem. A healthy benthic community in the mid-Atlantic is characterized by high biodiversity of benthic flora and macrofauna [17]. Benthic communities are made up of a several different types of organisms including many invertebrate species [86]. Benthic organisms play important roles in ecosystems because they are a fundamental part of the food web. They act both as a food source for larger organ-

isms and as decomposers, helping bacteria break down organic matter [86].

actually utilize these habitats created by oysters for other needs.

Improved water quality and continuity of a healthy food chain, benthic/pelagic coupling, and planktonic stability by oysters have provided valuable benefits to estuaries [60]. Posey et al. [48] examined whether resident and transient species are in fact attracted to the physical structures of the oysters for feeding or if they receive the majority of their foods elsewhere and

In addition to their impacts as a filter feeder to clarify water, harvested oysters left unharvested would remove excess nutrients from the bay incorporated within the oysters shell

and nutrients [57].

trophic levels.

The Eastern oyster (*Crassostrea virginica)* serves as an essential connection between pelagic and benthic food webs. Oysters consistently remove suspended organic and inorganic particles >3 μm in diameter with much effectiveness [45]. Since it only takes up around 70% of the filtered organic material, this leaves dense, mucus-bound biodeposits, also known as pseudofeces which are ejected. These biodeposits can serve as a valuable food source for benthic organisms. Oyster reefs also prompt phytoplankton productivity in natural, non-eutrophic systems by vigorously filtering suspended materials, lowering turbidity that may restrict light penetration and oyster growth [45]. Increased water clearness will in turn promote growth of benthic algae and diatoms that are a substantial food source for sessile and mobile benthic herbivores that in turn are eaten by many carnivorous fish [3]. However, the function of oysters mineralizing organic carbon and converting nitrogen and phosphorus into forms usable by primary producers may be more critical than serve as the primary consumer in the salt marsh [46]. Oysters can enhance the reduction of ammonium to nitrites and nitrates through their biodeposition by taking N from the water column and depositing it into sediments. Microbes can then reduce the nitrogen to N2 gas, which sublimates into the atmosphere. This is especially relevant in anthropogenically enriched environments [3, 46].

As [58] discussed oyster reefs have been considered as an essential fish habitat (EFH) for the last few decades. Many fish rely on oyster reefs for feeding, reproduction, and protection from predation. Within the same brief period during mid-summer, peak recruitment for all oyster reef residents occurs. This associates managing harvest and restoration efforts. Disruption of oysters by the addition of shell or dredging the reef during the spring through early autumn breeding season could negatively affect reproduction of many fish by burying nests, breaking apart articulated shells or scaring off males guarding their eggs [47].

Many economically important species may utilize oyster reefs for valuable juvenile nursery habitat Posey et al. [48]. Nursery habitat function of reefs may be expanded by locating restored reefs in shallow (<2 m deep) waters where large fish predators are less abundant. Important refuge habitats in estuaries are shallow water reefs. These reefs can also provide alternative foraging habitats for fish and crabs that are may be displaced by anoxic or hypoxic conditions as in the Chesapeake Bay, the Delaware Coastal Bays, the Gulf of Mexico and elsewhere [49].

Other nearby habitats can be influenced by oysters as well, like those of a salt marsh. This influence is achieved by protecting the salt marsh from the influences of wave energy. Shoreline retreat was significantly lower in a Louisiana study at sites with a constructed intertidal reef only 0.7 m tall in low energy areas. Low and high energy sites both showed positive oyster growth and recruitment (4.9 spat per shell) and showed potential to help stabilize sediment, reducing erosion, as well as providing salt marsh habitat in addition to a habitat of its own [50]. Because oyster reefs in salt marshes trap sediments as they grow, they can eventually become colonized by *Spartina* spp. and other grasses. Subsurface or fossil oyster reefs have been discovered extending from an existing reef into the marsh [46]. Indeed, bivalves can affect a shift in the phytoplankton community. Many authors have suggested that bivalves exert a "top-down" control of phytoplankton dynamics [51–54]. Some have stated in certain instances there exists a synergistic feedback. Oysters considerably advance the timing of nutrient recycling rates, allowing indulgence consumption and fast growth of some algal species [55, 56]. Through continuous filtering activities of the oysters, the phytoplankton community is shifted from older lag phase cells to younger cells in a logarithmic growth phase. Reduced competition causes the phytoplankton community to shift to faster growing algal species that are able to take advantage of the increased light and nutrients [57].

an estuary with less salinity, they have slower growth rates. This is primarily due to a lack of food availability. In addition, because "drills, starfish, and boring sponges cannot stand the reduced salinities that prevail" in areas farther up in estuaries, oysters are able to have a

The Eastern oyster (*Crassostrea virginica)* serves as an essential connection between pelagic and benthic food webs. Oysters consistently remove suspended organic and inorganic particles >3 μm in diameter with much effectiveness [45]. Since it only takes up around 70% of the filtered organic material, this leaves dense, mucus-bound biodeposits, also known as pseudofeces which are ejected. These biodeposits can serve as a valuable food source for benthic organisms. Oyster reefs also prompt phytoplankton productivity in natural, non-eutrophic systems by vigorously filtering suspended materials, lowering turbidity that may restrict light penetration and oyster growth [45]. Increased water clearness will in turn promote growth of benthic algae and diatoms that are a substantial food source for sessile and mobile benthic herbivores that in turn are eaten by many carnivorous fish [3]. However, the function of oysters mineralizing organic carbon and converting nitrogen and phosphorus into forms usable by primary producers may be more critical than serve as the primary consumer in the salt marsh [46]. Oysters can enhance the reduction of ammonium to nitrites and nitrates through their biodeposition by taking N from the water column and depositing it into sediments.

As [58] discussed oyster reefs have been considered as an essential fish habitat (EFH) for the last few decades. Many fish rely on oyster reefs for feeding, reproduction, and protection from predation. Within the same brief period during mid-summer, peak recruitment for all oyster reef residents occurs. This associates managing harvest and restoration efforts. Disruption of oysters by the addition of shell or dredging the reef during the spring through early autumn breeding season could negatively affect reproduction of many fish by burying nests, breaking

Many economically important species may utilize oyster reefs for valuable juvenile nursery habitat Posey et al. [48]. Nursery habitat function of reefs may be expanded by locating restored reefs in shallow (<2 m deep) waters where large fish predators are less abundant. Important refuge habitats in estuaries are shallow water reefs. These reefs can also provide alternative foraging habitats for fish and crabs that are may be displaced by anoxic or hypoxic conditions as in the Chesapeake Bay, the Delaware Coastal Bays, the Gulf of Mexico and

Other nearby habitats can be influenced by oysters as well, like those of a salt marsh. This influence is achieved by protecting the salt marsh from the influences of wave energy. Shoreline retreat was significantly lower in a Louisiana study at sites with a constructed intertidal reef only 0.7 m tall in low energy areas. Low and high energy sites both showed positive oyster growth and recruitment (4.9 spat per shell) and showed potential to help stabilize sediment, reducing erosion, as well as providing salt marsh habitat in addition to a habitat of its own [50]. Because oyster reefs in salt marshes trap sediments as they grow, they can eventually become colonized by *Spartina* spp. and other grasses. Subsurface or fossil oyster reefs have been discovered extending from an existing reef into the marsh [46].

gas, which sublimates into the atmosphere. This

higher rate of survivorship in these zones ([43], cited by [44]).

48 Aquaculture - Plants and Invertebrates

Microbes can then reduce the nitrogen to N2

elsewhere [49].

is especially relevant in anthropogenically enriched environments [3, 46].

apart articulated shells or scaring off males guarding their eggs [47].

*Crassostrea virginica* are bivalve suspension-feeder organisms that are native to the Delaware Inland Bays and Apalachicola Bay areas. Bivalve suspension feeders have been shown to serve an important biogeochemical role in coastal ecosystems because N and P from the water column are transferred to the sediments in their biodeposits [3]. This means that the filtration of the oysters can be shown to remove nitrogen from an aquatic ecosystem. Although the benefits of physical oyster structure may be significant, the benefits from oysters' ecological function are under-appreciated [58]. Although many studies have been done to focus on various effects of oyster ecology on lower trophic levels, resident species, and water quality, very few studies have yet conclusively demonstrated net benefits to higher trophic levels.

One of few studies showed where oysters enrich the surrounding benthos with their biodeposits and dissolved nutrients increases meio- and macrofauna species assemblage in their study [46]. Also observed by Bahr and Lanier [46], many oyster reef residents feed upon these lower trophic levels and find aid in the unique niches created by the oysters. Polychaete were collected from the sediments under the oyster gears, 1 meter away from the gears and 5 meters away from the gear in the Delaware Inland Bays. Polychaete survey results during the warmer months indicate the highest abundance of polychaetes were found at the Little Assawoman site and the lowest abundance of polychaetes in Rehoboth Bay. The results of the benthic community assessment indicate that there was no significant impact to Polychaete abundance or species richness from the oysters and aquaculture gear. Little Assawoman Bay had higher abundance and species richness than other two bays [59]. Benthic community assessments are often used to evaluate the health of an ecosystem. A healthy benthic community in the mid-Atlantic is characterized by high biodiversity of benthic flora and macrofauna [17]. Benthic communities are made up of a several different types of organisms including many invertebrate species [86]. Benthic organisms play important roles in ecosystems because they are a fundamental part of the food web. They act both as a food source for larger organisms and as decomposers, helping bacteria break down organic matter [86].

Improved water quality and continuity of a healthy food chain, benthic/pelagic coupling, and planktonic stability by oysters have provided valuable benefits to estuaries [60]. Posey et al. [48] examined whether resident and transient species are in fact attracted to the physical structures of the oysters for feeding or if they receive the majority of their foods elsewhere and actually utilize these habitats created by oysters for other needs.

In addition to their impacts as a filter feeder to clarify water, harvested oysters left unharvested would remove excess nutrients from the bay incorporated within the oysters shell and tissue [3]. Floating aquaculture gear would increase species diversity in the Delaware Inland Bays by providing refuge and foraging areas for transient species moving throughout the Delaware Inland Bays [21, 24, 61]. The years of research efforts conducted by the primary author and her research team found [62, 63], unlike some finfish farming, rearing shellfish in high densities in shallow water can have positive effects on the environment and may promote biodiversity. In the Delaware studies conducted around the submerged aquaculture equipment, 17 species showing significantly greater abundance and richness than in adjacent low-profile oyster shell reefs in 2006. Fourteen species around the equipment vs. the eutrophied, turbid, soft-bottom lagoon (including 3 species that require oyster shells for spawning substrate) in 2007. About 49 species of fish and invertebrates along with 8 species of macroalgae greatly contributing to the diversity of the native ecological community in 2008. In Virginia, 45 species of macrofauna were recorded inhabiting one commercial oyster farm that used floating equipment. In a study in Rhode Island, species richness was significantly greater in submerged aquaculture equipment than in a nearby seagrass bed or an unvegetated sand flat, especially for fishes and invertebrates in their early life stages, demonstrating the equipment may benefit some species more than others. These studies are critical to understanding the complex ecological interactions that occur and will allow farmers, managers, and regulators to fully appreciate the consequences of their actions. **Figure 11** shows the aquaculture gears used for the oyster gardening program and previous studies.

The potential effect of utilizing shellfish aquaculture for community-based restoration and environmental conservation is promising. **Figure 12** shows 2011 shellfish harvesting status of the Delaware Inland Bays [64]. Suitable locations for spat recruitment and oyster growth can be used to advance natural oyster settings. Number of oyster gardeners currently involved in the Delaware Inland Bays (DIB) oyster restoration efforts is about 200 community volunteers using their docks. Working with this number, and that fact that each oyster filters approximately 190 liters of water per day, the oysters currently involved in the program filter about 7,570,825 liters of water per day in the Delaware Inland Bays. Although this may seem to be an impressive amount, it is not when observing the actual volume of the Delaware Inland Bays. The Delaware Inland Bays have a surface area of 83 square kilometers, with an average depth of 1.2 meters [15]. This is a total volume of 101 billion liters. In order to filter the volume of water in the Delaware Inland Bays once daily, at least 534 million more oysters need to be cultivated and allowed to live without harvest. There are currently about 40,000 oysters. Once the critical amount of at least 534 million oysters is established, only then will there be at a point where there will be excess for actual harvesting. Only just beginning to touch the tip of the proverbial iceberg in Delaware with the restoration project, many more efforts are required.

According to Delaware Center for the Inland Bays Report [64], the Delaware Inland Bays are a premier east coast fishing destination, but important state fishes like the weakfish and blue crab population are declining. While the Inland Bays Oyster Gardening Program and student research projects confirm oysters can grow successfully in all three bays, wild oysters

**Figure 11.** Aquaculture gears used during the oyster gardening program. *Pictures by Frank Marenghi and Patrick Erbland.*

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

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

51

Fulford et al. [65] shares findings suggest that the ecological benefit of restoring bivalve populations are somewhat variable. A comparative model analysis of restoration plans in specific systems can be highly beneficial to maximizing the benefit-to-cost ratio of restoration efforts intended to reduce the negative effects of cultural eutrophication. It should also be noted that we should be cautious of generalizations about the effect of suspension-feeding benthos on phytoplankton without due consideration of estuarine size, circulation patterns, and morphology, as well as any other factors that may regulate community filtering

are very limited.

Habitat restoration and major pollution reductions are needed to restore water quality and achieve a healthy estuary once again. Unfortunately, areas close to the shoreline and most tributaries have unhealthy oxygen levels with severe condition in some areas although most open water areas have good dissolved oxygen for healthy aquatic lives. One of the major causes for poor water quality condition for low dissolved oxygen is due by the excess nutrient leading major habitat loss and degradation issues for variety of finfish, shellfish and other aquatic species including invertebrates [64].

Are Aquaculture Practices Sustaining Our Goal to Restore Oysters (*Crassostrea virginica*)? http://dx.doi.org/10.5772/intechopen.78989 51

and tissue [3]. Floating aquaculture gear would increase species diversity in the Delaware Inland Bays by providing refuge and foraging areas for transient species moving throughout the Delaware Inland Bays [21, 24, 61]. The years of research efforts conducted by the primary author and her research team found [62, 63], unlike some finfish farming, rearing shellfish in high densities in shallow water can have positive effects on the environment and may promote biodiversity. In the Delaware studies conducted around the submerged aquaculture equipment, 17 species showing significantly greater abundance and richness than in adjacent low-profile oyster shell reefs in 2006. Fourteen species around the equipment vs. the eutrophied, turbid, soft-bottom lagoon (including 3 species that require oyster shells for spawning substrate) in 2007. About 49 species of fish and invertebrates along with 8 species of macroalgae greatly contributing to the diversity of the native ecological community in 2008. In Virginia, 45 species of macrofauna were recorded inhabiting one commercial oyster farm that used floating equipment. In a study in Rhode Island, species richness was significantly greater in submerged aquaculture equipment than in a nearby seagrass bed or an unvegetated sand flat, especially for fishes and invertebrates in their early life stages, demonstrating the equipment may benefit some species more than others. These studies are critical to understanding the complex ecological interactions that occur and will allow farmers, managers, and regulators to fully appreciate the consequences of their actions. **Figure 11** shows the aquaculture

The potential effect of utilizing shellfish aquaculture for community-based restoration and environmental conservation is promising. **Figure 12** shows 2011 shellfish harvesting status of the Delaware Inland Bays [64]. Suitable locations for spat recruitment and oyster growth can be used to advance natural oyster settings. Number of oyster gardeners currently involved in the Delaware Inland Bays (DIB) oyster restoration efforts is about 200 community volunteers using their docks. Working with this number, and that fact that each oyster filters approximately 190 liters of water per day, the oysters currently involved in the program filter about 7,570,825 liters of water per day in the Delaware Inland Bays. Although this may seem to be an impressive amount, it is not when observing the actual volume of the Delaware Inland Bays. The Delaware Inland Bays have a surface area of 83 square kilometers, with an average depth of 1.2 meters [15]. This is a total volume of 101 billion liters. In order to filter the volume of water in the Delaware Inland Bays once daily, at least 534 million more oysters need to be cultivated and allowed to live without harvest. There are currently about 40,000 oysters. Once the critical amount of at least 534 million oysters is established, only then will there be at a point where there will be excess for actual harvesting. Only just beginning to touch the tip of the proverbial iceberg in Delaware with the restoration project, many more efforts are

Habitat restoration and major pollution reductions are needed to restore water quality and achieve a healthy estuary once again. Unfortunately, areas close to the shoreline and most tributaries have unhealthy oxygen levels with severe condition in some areas although most open water areas have good dissolved oxygen for healthy aquatic lives. One of the major causes for poor water quality condition for low dissolved oxygen is due by the excess nutrient leading major habitat loss and degradation issues for variety of finfish, shellfish and other

gears used for the oyster gardening program and previous studies.

required.

50 Aquaculture - Plants and Invertebrates

aquatic species including invertebrates [64].

**Figure 11.** Aquaculture gears used during the oyster gardening program. *Pictures by Frank Marenghi and Patrick Erbland.*

According to Delaware Center for the Inland Bays Report [64], the Delaware Inland Bays are a premier east coast fishing destination, but important state fishes like the weakfish and blue crab population are declining. While the Inland Bays Oyster Gardening Program and student research projects confirm oysters can grow successfully in all three bays, wild oysters are very limited.

Fulford et al. [65] shares findings suggest that the ecological benefit of restoring bivalve populations are somewhat variable. A comparative model analysis of restoration plans in specific systems can be highly beneficial to maximizing the benefit-to-cost ratio of restoration efforts intended to reduce the negative effects of cultural eutrophication. It should also be noted that we should be cautious of generalizations about the effect of suspension-feeding benthos on phytoplankton without due consideration of estuarine size, circulation patterns, and morphology, as well as any other factors that may regulate community filtering

water and its biota. They have also gained an appreciation for the Eastern oyster species, C*rassostrea virginica*, and the efforts of its restoration. Oyster culture has a potential to lessen pressure on natural overexploited populations and to generate income for coastal communities [67]. There are various social and economic benefits of oyster gardening in their local habitats in relation to watershed improvements discussed by Ozbay and Cannon [68]. The implications of these gardeners' actions are exponential in their ability to offer essential habi-

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

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

53

Environmental factors determine the productivity of the Apalachicola Bay oyster community: factors which encourage oyster growth include bottom substrate, nutrients from Apalachicola River and food availability. Those which are detrimental to oyster productivity include predation, disease, and sedimentation [69, 70]. Approximately, 10% of the bay's aquatic area is covered by oyster bars. Apalachicola Bay supplies the Florida seafood industry with 90% of its oysters. Local oyster harvesters and seafood suppliers rely on oysters for their livelihoods. The oyster industry brings \$10–\$14 million in revenue annually to Franklin County, FL; therefore, oyster productivity is linked to both ecosystem health and to financial solvency of the local

Approximately 17% of the bay's total area is occupied by fresh, brackish and salt water tidal marshes and only 7% of its area is occupied by seagrass, with the majority of these seagrass beds confined to high salinity and low turbidity regions of the bay [71]. The riverine discharge and associated seasonal flood-related flux of inorganic and organic nutrients into the bay from the Apalachicola River and its associated marsh systems is essential to the present ecosystem dynamics of the estuary [33, 72]. The bay also supports highly productive shellfish and finfish fisheries all of which are either directly or indirectly dependent upon the hydrologic conditions of the bay. For example, when the salinity of this estuary increases, oyster mortality rates increase due to predation by Gulf of Mexico gastropod mollusks and other predators, which require higher salinities [71, 73, 74]. Input of freshwater in river-dominated systems reduces

A study by Chanton and Lewis [72] compared ecosystem biogeochemical dynamics in Apalachicola Bay during periods of low river flow (summer-autumn) versus high flow (winter–spring). They demonstrated that floodplain detritus does not drive estuarine production in Apalachicola Bay but rather the highest estuarine productivity in Apalachicola Bay coincides with low flow period during the summer [72, 75–77]. The bay's primary productivity during these low flow periods, however, is driven by autochthonously produced dissolved nutrients coming from upstream [72] and/or possibly from marsh outwelling. Chanton and Lewis [72] also found that although consumers primarily utilize autochthonously produced substrates during periods of high river flow, the influx of terrestrial floodplain detritus does augment productivity in the bay. They concluded that reduced river flow would have a detrimental effect on overall estuarine production, especially during seasonal and extended droughts. The trophic status of the bay is therefore intricately linked to Apalachicola River's

As stated earlier, Deepwater Horizon Oil Spill has not significantly impacted Apalachicola Bay oysters. Compared to other areas along the Gulf Coast, the water quality in Apalachicola

predation pressure from marine species during high flow periods.

hydrologic regime, which impacts the bay.

tat revitalization.

economy.

**Figure 12.** 2011 shellfish harvesting status of the Delaware Inland Bays (Delaware Center for the Inland Bays 2013).

rates [66]. Keeping these thoughts in mind for future research potential, let us conclude with a short synopsis of how well oyster gardening is working in the DIB, and what steps need to be taken nest to maximize enhancement and restorations of both temperate and subtropical estuaries.

For the past 15 years, oyster gardening has been part of the restoration of the Delaware Inland Bays. Volunteers living in the local communities surrounding the DIB place floating baskets of oysters at the ends of their docks, allowing them protection from predation in order to grow from small, young spat into thriving adult oysters. Oyster aquaculture has a potential to generate income for coastal communities [67]. The volunteers who participate in the monitoring of water quality and oyster aquaculture have learned many things while becoming trained in aquaculture. They have realized an increase awareness to protect our water and its biota. They have also gained an appreciation for the Eastern oyster species, C*rassostrea virginica*, and the efforts of its restoration. Oyster culture has a potential to lessen pressure on natural overexploited populations and to generate income for coastal communities [67]. There are various social and economic benefits of oyster gardening in their local habitats in relation to watershed improvements discussed by Ozbay and Cannon [68]. The implications of these gardeners' actions are exponential in their ability to offer essential habitat revitalization.

Environmental factors determine the productivity of the Apalachicola Bay oyster community: factors which encourage oyster growth include bottom substrate, nutrients from Apalachicola River and food availability. Those which are detrimental to oyster productivity include predation, disease, and sedimentation [69, 70]. Approximately, 10% of the bay's aquatic area is covered by oyster bars. Apalachicola Bay supplies the Florida seafood industry with 90% of its oysters. Local oyster harvesters and seafood suppliers rely on oysters for their livelihoods. The oyster industry brings \$10–\$14 million in revenue annually to Franklin County, FL; therefore, oyster productivity is linked to both ecosystem health and to financial solvency of the local economy.

Approximately 17% of the bay's total area is occupied by fresh, brackish and salt water tidal marshes and only 7% of its area is occupied by seagrass, with the majority of these seagrass beds confined to high salinity and low turbidity regions of the bay [71]. The riverine discharge and associated seasonal flood-related flux of inorganic and organic nutrients into the bay from the Apalachicola River and its associated marsh systems is essential to the present ecosystem dynamics of the estuary [33, 72]. The bay also supports highly productive shellfish and finfish fisheries all of which are either directly or indirectly dependent upon the hydrologic conditions of the bay. For example, when the salinity of this estuary increases, oyster mortality rates increase due to predation by Gulf of Mexico gastropod mollusks and other predators, which require higher salinities [71, 73, 74]. Input of freshwater in river-dominated systems reduces predation pressure from marine species during high flow periods.

A study by Chanton and Lewis [72] compared ecosystem biogeochemical dynamics in Apalachicola Bay during periods of low river flow (summer-autumn) versus high flow (winter–spring). They demonstrated that floodplain detritus does not drive estuarine production in Apalachicola Bay but rather the highest estuarine productivity in Apalachicola Bay coincides with low flow period during the summer [72, 75–77]. The bay's primary productivity during these low flow periods, however, is driven by autochthonously produced dissolved nutrients coming from upstream [72] and/or possibly from marsh outwelling. Chanton and Lewis [72] also found that although consumers primarily utilize autochthonously produced substrates during periods of high river flow, the influx of terrestrial floodplain detritus does augment productivity in the bay. They concluded that reduced river flow would have a detrimental effect on overall estuarine production, especially during seasonal and extended droughts. The trophic status of the bay is therefore intricately linked to Apalachicola River's hydrologic regime, which impacts the bay.

rates [66]. Keeping these thoughts in mind for future research potential, let us conclude with a short synopsis of how well oyster gardening is working in the DIB, and what steps need to be taken nest to maximize enhancement and restorations of both temperate and

**Figure 12.** 2011 shellfish harvesting status of the Delaware Inland Bays (Delaware Center for the Inland Bays 2013).

For the past 15 years, oyster gardening has been part of the restoration of the Delaware Inland Bays. Volunteers living in the local communities surrounding the DIB place floating baskets of oysters at the ends of their docks, allowing them protection from predation in order to grow from small, young spat into thriving adult oysters. Oyster aquaculture has a potential to generate income for coastal communities [67]. The volunteers who participate in the monitoring of water quality and oyster aquaculture have learned many things while becoming trained in aquaculture. They have realized an increase awareness to protect our

subtropical estuaries.

52 Aquaculture - Plants and Invertebrates

As stated earlier, Deepwater Horizon Oil Spill has not significantly impacted Apalachicola Bay oysters. Compared to other areas along the Gulf Coast, the water quality in Apalachicola Bay has remained relatively unaffected, with the exception of tar balls washing ashore and some oil sheens. To enhance oyster landings after the spill, the state of Florida opened a 7-day-per-week oyster harvest at both the summer and winter harvesting grounds during June–August 2010; however, preliminary commercial landings reports suggest that Franklin County's 2010 oyster harvest was the lowest in 5 years, although landings from 2007 and 2009 were the highest in 20 years. Furthermore, the annual 2010 landings rate (pounds/trip) was the lowest since 1991 (**Figure 13**). This drop in oyster production and the over-tapping of the winter oyster beds translated into lost revenue, which reverberated throughout the Florida seafood and restaurant. The oyster fishery has not rebounded since 2011 and prices have increased (**Figure 13**). University of Florida researchers developed a population model to determine whether harvest of sub-legal oysters contributed to the crash in the Apalachicola Bay fishery while they found an increase in natural mortality [39, 78].

**5. Conclusion**

Here we discussed two different estuary systems with differences in ecosystem management goals and plans with different ecosystem indicators (TSS and turbidity in Delaware Inland Bays versus salinity in Apalachicola Bay), however both estuaries have few common issues mainly due to increase population and population driven activities (*see* **Table 3**). These issues include frequent eutrophication events, increase pollutants via storm water runoff, agricultural or residential areas, overfishing and habitat alterations. Both estuary systems have some indicators different from each other such as coral reefs and essential fish habitat for Apalachicola Bay versus essential fish habitat or areas that will be open to shellfish harvesting for the Delaware Inland Bays. Major alterations and changes to those fragile ecosystems are mainly due to anthropogenic activities and management goals for both estuaries should be to

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

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

55

Although decision and management strategies will be different, each estuary system or watershed, depending on the critical areas of concerns and related activities, solution is dependent upon how we plan our next action. Are we setting our goal for too short term or

**Criteria Delaware Inland Bays, DE Apalachicola Bay, FL**

water (Indian River Bay, Little Assawoman Bay,

in Delaware

• River-dominated estuary and lagoon in Florida. • Watershed - 540 km2

Alabama, Georgia and

• Average water depth of 2

• Natural oyster population dwindling, not rebounding

• Natural oyster population is

• Aquaculture is becoming

• Reduced freshwater input due to drought and upriver

• Estuary salinity increase • Increased predation • Most common issues are decrease in oyster population, approval of oyster

Florida

meters • Pristine system?

declining

popular

usage

aquaculture

in

minimize further changes and mitigate areas already altered.

Characteristics • Three low flushing interconnected bodies of

Oyster Population Status • Very limited oyster population

Challenges • Frequent eutrophication

Aquaculture Status • Aquaculture permits have been issued and approval obtained

residential runoff

related activities

aquaculture

• Human interference of habitat

• Overfishing • Habitat alterations

and Rehoboth Bay). • Watershed - 811 km2

• Average water depth of 1.2 meters • Frequent alteration to waterways?

• Restoration and mitigation are necessary

• However, implementation is very slow

• Increased pollutants from agricultural and

• Increase land uses due to human population and

• Very low natural oyster population and recruitment and approval and implementation of

Since natural oyster populations have been unable to keep up with demand let alone sustainable historic stocks, aquaculture has become an essential part of restoration and stock enhancement efforts. According to the California Aquaculture Association [79], the top U.S. marine aquaculture species was oysters. In 2015, U.S. shellfish farmers produced 15,876 metric tons of oysters at \$173 million market value [80]. According to Stewart [81], the farmed oyster production grew by 806% between 2006 and 2012 in Chesapeake Bay. Rheault (Executive Director of East Coast Shellfish Association) in Stewart's report stated that the east coast shellfish production for oysters has doubled in 5 years at a steady rate of 12% per year. With \$2 a pop on U.S. restaurant menus, associated demand for oysters are making oyster farming vital player in the United States.

**Figure 13.** Oysters catch per unit effort and average price per pound of oysters (*Data from Florida Fish and Wildlife Conservation Commission http://myfwc.com/, Figure by Smith (unpublished)).*
