STEELHEAD TROUT AND INTERGRATED MULTITROPHIC AQUACULTURE (IMTA)

This study investigated methods to promote small scale finfish aquaculture operations in New England with a focus on promoting year-round revenue for current and future aquaculture operations. The first portion of the study was to investigate the use of a recirculating aquaculture system to raise steelhead trout at a water temperature and feeding rate that optimized growth rates and promoted healthy livestock. The use of the recirculating system was to identify if artificially maintained temperatures can increase biomass production in steelhead trout culturing compared trout pond culturing. The studied also investigate the use of an integrated multi-trophic aquaculture approach (IMTA), which permitted the culturing of different species at different trophic levels. The intention of investigating IMTA was to assess its ability to increase the revenue of small shellfish farms by diversifying the livestock species cultivated while mitigating any negative side effects associated with finfish culture (Troell et al., 2009; Wang et al., 2012). In New England, growers primarily grow and sell oysters. However, oysters in New England don’t grow for about four months a year once water temperatures drop below 10 degrees Celsius. Diversifying the species cultured by aquaculture operations in New England states could provide year round revenue and jobs.

Recirculating Aquaculture System (RAS) steelhead trout culturing experiment:

During the recirculating aquaculture system phase of the study, average monthly growth rates (grams/day) increased linearly (R-Squared = 0.9643) at a rate of 1.68% total body weight per day. The Fulton’s condition factor (K) of the trout in the recirculating system also increased linearly (R-Squared = 0.9999). Fulton’s condition factor is a widely accepted metric for estimating the health of fish, such as rainbow trout, and can be an indicator of stress, reproductive status, nutrition and age (Sharma and Bhat, 2015; Dekic et al., 2016; Shabani et al., 2018). The equation used to calculate Fulton’s condition factor (K) was: K = ((W)/(L*3))*100 (Froese, 2006; Tasaduq et al., 2011; Sharma and Bhat, 2015; Dekic et al., 2016). The use of Fulton’s condition factor (K) allows for health comparisons to other studies involving rainbow trout culturing and health.

During the three month period in the recirculating aquaculture system, total trout length increased at an average daily rate of 1.13 mm/day (SD±0.73). The monthly average growth rates (mm/day) of steelhead trout remain consistent throughout the recirculating aquaculture system phase, ranging from 1.04 mm/day (SD±0.48) in September to 1.18 mm/day (SD±0.71) in October.

The recirculating system was an efficient technique in promoting high growth rates and good health of cultured trout. During the three month recirculating aquaculture system experiment, the steelhead trout held within the system experienced linear growth in weight at a controlled temperature (20 Celsius) and a maintained feeding regiment (~2% total biomass/daily). Over the duration of the recirculating aquaculture system portion of the experiment, the average individual trout weight increased linearly (R - Squared = 0.9643), increasing by approximately 1.68% increase in body weight daily while housed in the recirculating aquaculture system.

Steelhead trout IMTA net pen experiment:

Two netpens were installed by Ward Aquafarms into two identical slips at Fiddler’s Cove Marina, North Falmouth, MA in December of 2019. Ward Aquafarms already utilizes two other slips for float storage from October-May. By placing the net pens adjacent to an existing shellfish farm operation, additional labor costs were be reduced, and integration into standard farm operations was easily established. The two identical surface net pens (4m x 6m x 3m; custom nets from Reidar’s Nets, New Bedford, MA), were hung from existing finger piers, utilizing existing flotation and cleats. Total weight and total length measurements were sampled monthly from January through April of 2020 to evaluate growth.

While housed in the net pen during from December, 2019 through April, 2020, Steelhead trout growth rates in length ranged from 0.50 mm/day (SD±0.47) in December, 2019 to 0.07 mm/day (SD±0.53) in January, 2020. Steelhead trout growth rates in weight (g/day) during the net pen phase ranged from 2.03 grams/day (SD±1.49) in January, 2020 to a daily loss in weight of - 0.32 grams/day in February, 2020. Additionally, The Fulton’s condition factor (K) ranged from 1.29 (SD±0.12) in December, 2019 to 1.64 (SD±0.16) in January, 2020 for steelhead trout housed in net pens.

By the end of the net pen portion of the study, the condition factor of the rainbow trout population transferred from the recirculating system had changed little, and even experienced decreases. On April 1st, 2020, after 118 days in the net pens, the condition factor of the trout population from the recirculating aquaculture system was 1.56 (SD±0.13), a slight decrease from their initial condition factor of 1.58 (SD±0.11). Given that the condition factor of the trout population did not increase during the net pen culturing, and actually decreased in some sampling months, any reductions in the condition factor of the trout while housed in net pens will be difficult to recover from. The higher the condition factor of a trout population upon deployment into net pens, the greater the buffer against any decreases in condition. Since the trout population experienced a continuous increase in its condition factor while housed in recirculating aquaculture system, increasing the amount of time the trout population stays in recirculating aquaculture system would make for a safer and more profitable net pen culturing.

While in the recirculating system the average trout weight nearly doubled every 30 days, increasing at an average rate of 1.88 grams/day (SD±1.48). Once the trout were transferred to net pens the average growth rate of 0.76 grams/day (SD±1.76). Reductions in weight gains of the steelhead trout while housed in the net pens was anticipated though, for reductions in water temperature are known to decrease growth rates in rainbow and steelhead trout (Myrick and Cech, 2000 and 2005; Richter and Kolmes, 2005). All significant gains in weight (i.e. biomass) were intended to occur during the recirculating system phase. Therefore, the only way to increase the size of the trout while being held in net pens pending sale during winter months is increase the size of the trout prior to transfer into net pens. Extending the duration in which the trout are housed in the recirculating aquaculture system would produce a larger, more valuable product for sales during the net pen holding phase.

IMTA kelp and shellfish:

Oysters and bay scallops were stocked at two locations in December 2019: 1) directly adjacent to the trout netpens in the same slip; and 2) in outer Megansett at the farm growout site. Additionally, sugar kelp seed string was purchased from a locally available seed string supplier. Three, identical 20’ lines of sugar kelp were installed adjacent to both the trout net pens, and three identical lines were also installed at the current Megansett Harbor oyster farm. The lines were installed starting at the northwest corner, leading from north to south, spaced 25’ apart. The line was then sunk to 7’ at all locations.

The idea of practicing IMTA was mitigate any negative ecological impacts of the steelhead trout by using shellfish and macroalgae (sugar kelp) to consume excess nutrients while also producing extra aquaculture products (Troell et al., 2009; Wang et al., 2012). No significant differences were seen in growth rates and final shell heights of oysters and bay scallops housed near net pens in versus those housed at the control site.

A factor that likely influenced shellfish growth, or the lack thereof, was water temperature which remained below 7 degrees. Oyster metabolism and feeding rapidly decreases as waters temperatures drop below 10 degrees Celsius and bay scallop metabolism and feeding halts at temperatures below (Kirby-Smith and Barber, 1974; Barber and Blake, 1983; Dekshenieks et al., 1993; Comeau et al., 2008). Thus, the addition of oysters and bay scallops to Steelhead trout IMTA during winter months may add extra work with no economic gains.

However, the sugar kelp housed next to the trout net pens did exhibit significantly higher growth than the kelp at the control site.

With the ecological benefits associated with growing sugar kelp coupled with the significant growth, growing kelp next to steelhead trout net pens not only potentially mitigates negative side effects associated with finfish pen culturing but also provides an additional sources of revenue.

Sources:

Barber, B.J. and N.J.  Blake. 1983. Growth and reproduction of the bay scallop, Argopecten irradians (Lamarck) at its southern distributional limit. Journal of Experimental Marine Biology and Ecology. 66(3): 247 – 256.

Comeau, L.A., Pernet, F., Tremblay, R., Bates, S.S., and A. Leblanc. 2008. Comparison of eastern oyster (Crassostrea virginica) and blue mussel (Mytilus edulis) filtration rates at low temperatures. Canadian Technical Report of Fisheries and Aquatic Sciences. 2810.

Dekic, R., Savic, N., Manojlovic, M., Golub, D., and J. Pavlicevic. 2016. Condition factor and organosomatic indices of rainbow trout (Onchorhunchus mykiss, Wal.) from different brood stock. Biotechnology in Animal Husbandry. 32(2): 229-237.

Dekshenieks, M.M., Hofmann, E.E., and E.N. Powell. 1993. Environmental Effects on the Growth and Development of Eastern Oyster, Crassostrea virginica (Gmelin, 1791), Larvae: A Modeling Study. Journal of Shellfish Research. 12(2): 241 – 254.

Kirby-Smith, W.W. and R.T. Barber. 1974. Suspension-feeding aquaculture systems: Effects of phytoplankton concentration and temperature on growth of the bay scallop. Aquaculture. 3(2): 135 – 145.

Myrick, C.A. and J.J. Cech Jr. 2000. Temperature influences on California rainbow trout physiological performance. Fish Physiology and Biochemistry. 22: 245-254.

Myrick, C.A. and J.J. Cech. Jr. 2005. Effects of temperature on growth, food consumption, and thermal tolerance of age-0 nimbus-strain steelhead. North American Journal of Aquaculture. 67: 324-330.

Richter, A. and S.A. Kolmes. 2005. Maximum temperature limits for Chinook, coho, and chum salmon, and steelhead trout in the Pacific Northwest. Reviews in Fisheries Science. 13: 23-49.

Shabani, F., Beli, E. and A. Rexhepi. 2018. Length-weight relationship and Fulton’s condition factor of rainbow trout (Oncorhynchus mykiss). Albanian Journal of Agricultural Science. 17(2): 261-264.

Sharma, R.K. and R.A. Bhat. 2015. Length-weight relationship, condition factor of rainbow trout (Oncorhynchus mykiss) from Kashmir waters. Annals of Biological Research. 6(8): 25-29.

Tasaduq, H.S., Balkhi, M.H., Najar, A.M., and O.A. Asimi. 2011. Morphometry, length-weight and condition factor of farmed female rainbow trout (Oncorhynchus mykiss Walbaum) in Kashmir. Indian Journal Fisheries. 58(3):51-56.

Troell, M., Joyce, A., Chopin, T., Neori, A., Buschmann, A.H., and J.G. Fang. 2009. Ecological engineering in aquaculture – potential for intergrated multi-trophic aquaculture (IMTA) in marine offshore systems. Aquaculture. 297: 1-9.

Wang, X., Olsen, L.M., Reitan, K.L., and Y. Olsen. 2012. Discharge of nutrient wastes from salmon farms: environmental effects and potential for integrated multi-trophic aquaculture. Aquaculture Environment.

TAUTOG AQUACULTURE

Tautog (Tautoga onitis) is a coastal wrasse which is a highly sought-after species by commercial and recreational anglers. Due to the high demand and stressed wild populations, tautog is an ideal candidate species for marine aquaculture. Additionally, tautog are voracious feeders of the invasive green crab (Carcinus maenas), which have caused widespread ecological damage along the east coast. The proposed project would refine culturing techniques for this high value food fish, while creating a market for an invasive species endemic throughout the Northeast region.

In 2019, Ward Aquafarms partnered with the University of Massachusetts Dartmouth to evaluate the use different diet treatments on the growth rates of aquacultured tautog. The major goal of the study was to assess if the addition of the invasive green crab to the diet of tautog resulted in higher growth rates than a diet consisting of commercially available fish feed. To assess the benefits of a green crab diet on aquacultured tautog, three different diets were tested: 1) Natural: green crabs only; 2) Zeigler: commercially available marine finfish diet; 3) Natural + Zeigler: green crabs supplemented with commercial feed. Tautog used in the study were obtained during the months of May and June 2019, year 1 tautog ranging from 5 to 10mm in size were obtained via a series of beach seines were conducted at Megansett Harbor in North Falmouth, MA and Monk’s Cove in Bourne, MA.

The tautog were seperated into the three groups and fed the three aforementioned feeding regiments. The fish were held in recirculating systems at UMass Dartmouth’s wet lab located at the School for Marine Science and Technology (SMAST) in New Bedford, MA.

Each treatment was composed of three replicate 750L flow through tanks housing 50 tautog each. The replicate tanks had controlled temperature (~25 Celsius), salinity (30-32 psu), lighting (12L:12D) and aeration. Every 30 days, all tautog from each replicate were sampled for total length (cm) and weight (g).

Feeding amounts were determined based on satiation and administered at each feeding interval. Increases in feeding were decided based on percent growth and satiation. Satiation was determined by whether there was any left-over food left in the tanks after feeding. The amount of commercial feed added was determined by 2% of the total body weight and observational record of uneaten food in the tanks. The amount of crab was determined by a total of 40% of the total weight of the fish, while also keeping track of whether or not all the food was being eaten in the tanks. Feeding to satiation while avoiding excess food in the tanks was important to ensure high water quality and growth.

Phase one of Ward Aquafarms’ tautog aquacultrure research was conducted from August, 2019 through March, 2020. Results from phase one of the study indicate that a green crab supplemented diet for aquacultured tautog could be viable as an aquaculture species. Tautog fed a diet of green crab only had an average daily growth rate of 0.52 mm/day (SD ± 0.10), which was a significantly higher daily growth rate compared to the growth rate of 0.31 mm/day (SD ± 0.1) for tautog fed a diet of commercial feed only. The growth rate of tautog fed the commercial feed only diet was also significantly lower than 0.46 mm/day (SD ± 0.09) for tautog fed a mixed diet of green crab and commercial feed.

Tautog fed a diet of only green crab had an average daily weight gain of 0.80 grams/day (SD±0.29) during the eight month feeding trial (August, 2019 - March, 2020) and had an average weight of 207.5 grams (SD±72.5) at the end of the experiment in April, 2020. The tautog fed a mixed diet of green crab and commercial feed during the seven month feeding trial had an average daily weight gain of 0.63 (SD±0.23) and an average final weight of 166.2 grams (SD±57.1). The average daily weight gains and average final weights of the tautog fed green crab and a mixed diet of green crab and commercial feed were significantly higher than the average daily weight gain of 0.34 grams/day (SD±0.17) and final mean weight of 92.9 grams (SD±42.6) of tautog fed a commercial feed only diet.

The results from the eight month tautog feeding trial conducted by Ward Aquafarms in collaboration with partners from University of Massachusetts Dartmouth indicate that the use of green crab significantly increases weight and length growth in tautog compared to a diet of commercially available fish food. Thus, the use of green crab as feed for tautog could help make tautog a viable species for aquaculture. Additionally, the harvesting of green grab for fish feed will help combat the negative ecological effects green crabs have on the environments they have invaded in North America. Although results from this study were very promising, Ward Aquafarms and their collaborators are further investigating the use of green crab feed in tautog aquaculture in order to fully understand the procedures to successfully aquaculture tautog on a commercial scale.

QUAHOGS AKA HARD CLAMS

For more information or to purchase quahogs, please contact us at hello@wardaquafarms.com

Bay Scallop (Argopecten irradians)

Early Research

Ward Aquafarms began growing bay scallops in 2014. In the first year of bay scallop culturing, Ward Aquafarms identified two major issues associated with using the same FLUPSY nursery system the farm used to rear oysters. The first major problem was that bay scallops would swim up and out of the silo. This issue was partially fixed by placing mesh over the small outflow pipe, but at the cost of significantly reducing flow and food availability. The second issue occurred as the bay scallops grew in size and space within the FLUPSY silos became more limited. As previously mentioned, bay scallops can swim. To create propulsion to swim, bay scallops rapidly open and close their shells. If bay scallops are too heavily stocked, they can cut into each other (referred to as “knifing”), causing physical harm and stress. Growth rates of the bay scallops decreased significantly with size due to stress associated with stocking density.

Downweller System

 In 2015, Ward Aquafarms developed their first floating downweller system, which reversed the direction of flow compared to the previously used oyster FLUPSY. The reversed flow prevented bay scallop escapement. Additionally, the downweller used a nested tray system that significantly increased surface area compared to the FLUPSY, allowing bay scallops to be stocked at densities that promoted optimal health and growth of the housed bay scallops. Since 2015, Ward Aquafarms has experimented with different stocking densities and mesh sizes in the downweller system to promote the highest growth rates and survival during the nursery phase of bay scallop aquaculture.

 Nursery Investigations

 After the success of the downweller system in 2015, Ward Aquafarms has experimented with other nursery growing methods. In addition to experimentally culturing bay scallop seed in FLUPSYs and downweller systems, Ward Aquafarms tested the use of bottom gear, land based upwellers and lantern net as potential options for optimization in the nursery phase of bay scallop aquaculture. When assessing “optimization” of a nursery system, Ward Aquafarms looked for three main factors: 1) Survival (i.e., the percentage of bay scallops out of the starting population that survive to the end of the nursery phase; 2) Grow rates (i.e., the amount of daily new shell growth; 3) The number of bay scallops each system produces.

For bay scallops cultured in bottom bags during the nursery phase, survival and growth rates were extremely low, indicating that bottom bags are not a sufficient bay scallop nursery method. Land based upwellers, lantern nets, and the downweller systems all had high survival and growth rates. However, the downweller system was able to produce a significantly higher amount of bay scallops compared to the lantern nets and land based upwellers. The reason the downweller was able to produce such a high number of bay scallops at the end of the nursery phase was because of the system’s stacked tray design that allowed for multiple layers of bay scallops to be cultured in a single silo without crowding. Overall, the results illustrate that if an operation seeks to optimize survival, growth and production, the downweller is the best nursery choice. However, lantern nets and landbased upwellers are also good options for optimizing growth and survival.

Grow-out Investigations

In 2017 and 2018, Ward Aquafarms investigated different bay scallop grow-out gear types at four commercial aquaculture locations on Cape Cod, MA: Megansett Harbor, Woods Hole, Wellfleet, and Truro. Each site had unique site specific environmental parameters.

Megansett Harbor has a depth of 3 m MLW (mean low water) and a sandy substrate. Woods Hole is a commercial aquaculture farm with a depth of 5 m MLW and muddy substrate. Wellfleet is a commercial intertidal farm with a depth of 1 m MLW and a primarily muddy substrate. Finally, Truro is a deep water commercial aquaculture farm with a depth 8 m MLW and a sandy substrate.

Results from the grow-out studies indicate that bay scallops are not viable for intertidal farms, such as the Wellfleet location, or farms with high amounts of wind and wave activity, which was observed at the Truro farm. The best growth, survival and meat yield (# of shucked scallops/pound) was observed when bay scallops were housed in surface gear at the Woods Hole farm location, which represents a location sheltered from wind and wave activity. The Megansett Harbor location was also promising, but the site’s exposure to wind and waves resulted in the loss and damage of surface gear.

Restoration and Stock Enhancement

 Since 2016, Ward Aquafarms has been providing the towns of Bourne and Falmouth, Massachusetts with bay scallop seed for restoration and stock enhancement projects. Wild bay scallop stocks have been depleted since the fishery collapsed in the 1980’s due to overfishing and eelgrass bed depletion. Eelgrass is essential nursery habitat for bay scallop seed. With most beds a fraction of what they used to be, predation on bay scallop seed is very high, leading to minimal recruitment and stock replenishment. The work Ward Aquafarms conducts with the towns of Bourne and Falmouth bypasses the bay scallop lifestage that is dependent on eelgrass for protection. The intention of growing bay scallops to a size that no longer needs eelgrass for protection is to mitigate loss caused by predation and increase year two bay scallop populations which can be harvested by recreational and commercial shellfishermen.

Bay scallop parasite studies

Since 2016, Ward Aquafarms has been investigating the effects of macroparasites on bay scallop meat yield as a potential mitigation techniques. The two major parasites which Ward Aquafarms has looked at in their studies are mud blister worms (Polydora spp.) and pea crabs (Pinnotheres maculatus).

Pea crabs infect their host by crawling into the mantle cavity of the shellfish. Once inside, the pea crabs cause physical irritation to the gonads and gills while simultaneously taking food directly away from the host by removing food particles from the host’s gills.

Mud blister worms are parasitic polychaete worms that burrow into the shell of the host shellfish. As they burrow towards the mantle cavity tissue of the host shellfish, the host shellfish creates the “mud blister” around the irritated area. In addition to the irritation caused by worms burrowing activity, the host must also redirect energy away from growth and reproduction to create the mud blister. Additionally, the presence of the mud blister can make efficiently shucking a bay scallop difficult.

To investigate parasite prevalence, Ward Aquafarms sampled bay scallops housed in both surface and bottom gear at four commercial aquaculture farms on Cape Cod, MA. At the sampling location where pea crabs were primarily found, surface gear appeared to significantly reduce pea crab prevalence compared to bay scallops housed in bottom gear. A similar trend was observed with mud blister worm prevalence, with a trend indicating surface gear may successfully reduce mud blister worm prevalence.

When looking at the depth of each commercial farm which bay scallops were sampled from, bay scallops housed in surface gear had a decreasing mud blister worm prevalence as the depth of the farm (i.e. distance surface gear was from the bottom) increased. Thus, the results suggest that mud blister worm prevalence in bay scallops housed in surface gear decreases as farm location depth increases. In other words, the increased site depth results in an increased reduction in mud blister worm prevalence of bay scallops housed in surface gear.

Propagation and ecological services

Ward Aquafarms has been partnering with local municipalities on and around Cape Cod, MA since 2016 to assist with their shellfish propagations programs. Since 2018, in partnership with the towns of Orleans, Dennis and Falmouth, Ward Aquafarms has raised shellfish with the goal of removing excess nitrogen from the ecosystem. Bioremedation is the removal of excess organic nutrient, such as nitrogen, via consumption by introduced or naturally occurring organisms. Excess organic nutrients can be a threat to both wildlife and humans, and is a common issue in populated coastal areas. In the bioremedation projects that Ward Aquafarms participates in, oysters and quahogs are used as bioremediating organism, in the sense that the oysters and quahogs naturally consume microalgae out of the water as their food sources. The microalgae species that oysters and quahogs consume are the consumers of the excess nitrogen. The oysters and quahogs are then available for harvest by recreational and commercial harvesters once the shellfish are of legal harvest size. Thus, the algae removes the nitrogen, the shellfish remove the algae, and then humans remove the shellfish. The final result is cleaner water and healthy food for harvest!

Bourne, MA:

Ward Aquafarms has partnered in propagation projects with the town of Bourne since 2016. Ward Aquafarms provides assistance during the nursery phase as well as deployment of bags during intermediate growout and bottom planting once the oysters, quahogs, bay scallops and soft shell clams have grown to a sufficient size.

Dennis, MA:

In 2019, Ward Aquafarms partnered with the town of Dennis to conduct a bioremediation project in Swan Pond. Swan pond has very high nitrogen levels, and therefore, excess microalgae (ie: oyster food). To assess if oysters could be a viable strategy to help reduce nitrogen levels in the pond, Ward Aquafarms deployed 500,000 oysters in June, 2019.

In August, 2019 a tornado came through the site on Swan Pond. Although entire lines bags full of oysters were picked up and tossed over each other and some lines were blown away, all bags were relocated on the pond and all the lines were placed back in their original location.

Orleans, MA:

Ward Aquafarms has been collaborating with the University of Massachusetts Dartmouth on commercial project in collaboration with the town of Orleans since May, 2019. In July and August of 2019, Ward Aquafarms deployed approximately 2,200,000 oysters in floating ADPI bags in Lonnie’s Pond.

The first year of the project was a huge success. Ward Aquafarms managed the farming aspect of the project, tending to the oysters from May through December, 2019.

At the end of December, 2019 the oysters were removed from the pond for overwintering or for final grow-out at Ward Aquafarms location in Megansett Harbor in North Falmouth, MA.

In April, 2020 Ward Aquafarms and the University of Massachusetts Dartmouth again deployed oysters at Lonnie’s pond to continue the town’s commercial project for another year after the successes of year one.

Falmouth, MA:

In May, 2020 Ward Aquafarms deployed their first round of oysters into the Eel River adjacent to Washburn Island in East Falmouth, MA. The oysters are part of multi-farm collaboration project with town of Falmouth to aid with excess nitrogen in the area while also producing oysters which the farmers can sell.

Landbased upwellers are being used by Ward Aquafarms to grow seed during the nursery phase. Once the oysters are of a sufficient size to be moved into grow-out bags, they will be transferred to the location on Eel Pond.

HARMFUL ALGAE BLOOM (HAB) RESEARCH

2016 Pilot Study

Cochlodinium polyrikoides is a commonly occurring species of harmful algae species seen in coastal regions globally (Lee and Lee, 2006; Tang and Gobler, 2008; Park et al., 2015; Kim et al., 2016). Harmful algae blooms (HABs), such as C. Poly blooms, occur in coastal regions and can have serious negative effects on commercial wild and aquacultured species (Tang et al., 2004; O’Neil et al., 2012). HAB events are increasing globally in frequency, maginitude and toxicity, and are estimated to have an economic effect of approximately USD $50 million annually in the United States (Hoagland et al., 2002; Jeong et al., 2008; Park et al., 2013).

C. poly blooms, or brown tides, have been increasing in distribution, duration, and frequency globally, including in the United States (Hoagland et al., 2002; Garate-Lizarraga et al., 2003; Rountos et al., 2014). C. poly is non-toxic to humans, but can have serious effects on juvenile shellfish and finfish, and is known to cause fish/shellfish kills globally (Lee and Lee, 2006; Gobler et al., 2008; Tang and Gobler, 2009). For Juvenille shellfish, such as bay scallops (Argopecten irradians) and American oysters (Crassostrea virginica), C. poly bloom events result in high mortality during blooms and reduced growth rates following blooms (Gobler et al., 2008; Tang and Gobler, 2008; Tang and Gobler, 2009).

In 2016, Ward Aquafarms, conducted a study during a C. poly bloom in Buzzard’s Bay and Fiddler’s Cove Marina in North Falmouth, MA. C. poly cell concentrations were calculated by obtaining water samples aforementioned locations and then performing C. poly cell counts. C. poly distribution and cell densities were documented in Fiddler’s Cove (nursery area) and Buzzard’s Bay, with C. poly cell densities highest in Fiddler’s Cove Marina adjacent to Ward Aquafarms shellfish nursery systems.

Ward Aquafarms also tracked the survival and growth rates of adult and juvenile oysters, clams and bay scallops during the 2016 C. poly bloom. With the C. poly cell densities highest adjacent to Ward Aquafarms’ oyster and bay scallop nursery systems in Fiddler’s Cove Marina, Ward Aquafarms was able to document what any negative effects in survival and growth caused by high concentrations of C. poly.

After 60 days, reductions in growth rates and survival for juvenile (< 10 mm) bay scallops, clams and oysters in the nursery systems were observed during the 2016 bloom. Juvenile oysters less than 10 mm had a mean±SD percent survival 49.9±5.4% and mean±SD growth rate of 0.03±0.0 mm/day. Juvenile oysters greater than 10 mm had a survival rate of 94.9±3.6% and a growth rate of 0.40±0.1 mm/day. Since C. poly densities were highest in the nursery area, and nursery size bay scallops, clams, oysters are the most impacted by C. poly blooms, strategies to mitigate the effects in the nursery area is of utmost importance. The results from Ward Aquafarms’ 2016 C. poly study launched a series of subsequent research on way to identify when a bloom is happening, how bad the bloom is, and ways to potentially mitigate the negative effects of a bloom.

Imaging FlowCytoBot (IFCB)

In 2017 and 2018 McLane Research Laboratories and Dr. Brosnahan (WHOI) partnered with Ward Aquafarms to determine strategies to mitigate HAB impacts on farmers, including early notification, ongoing monitoring, and farm management strategies. A cornerstone to these strategies is a new technology – called Imaging FlowCytobot (or IFCB) - that provides continuous, real-time, automated monitoring of the phytoplankton community around farms. Data produced by this sensor provide a massive leap forward for basic understanding and management of coastal ecosystems, while also informing managers, farmers and other stakeholder when a HAB is starting, growing or subsiding – all critical information to those aiming to mitigate HAB impacts.

The IFCB sensor is a submersible imaging-in-flow cytometer that acts as an automated microscope, collecting images of individual phytoplankton at up to 12 cell per second. Raw data from the instrument (~100,000 images a day)provides estimates of algae species’ concentrations and indicates physiological changes and important ecological interactions between species. Computer automated characterization of these types of changes can inform forecasts of a given species’ or bloom’s trajectory, ultimately providing farmers information about whether a HAB is increasing or waning so that they can act accordingly to protect their animals

The intent of the proposed project is to build on these preliminary results and to expand the benefits of real-time in situ microscopy and automated analysis software to farmers throughout the region. When farmers can be notified of bloom activity within the area of their farm, mitigation strategies such as moving shellfish to deeper water or areas of higher flow can be evaluated in terms of cost and permitting required. While it may be more labor intensive, if the shellfish can be moved either vertically within the water column, or to an adjacent water body, it often can be the difference between high mortality and low growth or a strong season which allows the farm to maintain economic viability.

In the summer of 2017, the project team completed a pilot IFCB deployment within the Ward Aquafarms nursery area in the same location. Immediate identification of C. polykrikoides when the IFCB was installed on July 28, 2017 led Dr. Ward to move juvenile oysters to an alternative grow site where harmful algal concentrations were much lower.  This action spared the farm from a much more significant loss of juvenile shellfish and demonstrated how knowledge of ongoing blooms can improve the profitability of the both the farm and its immediate neighbors. Future deployments of an IFCB will provide data and analytical products freely to farmers, managers, and other local and regional partners while also providing a needed data stream to prove a new automated system for protection of animals from C. polykrikoides exposure.

An initial classifier developed from the 2017 data set already shows great promise for automation of data analysis and will only improve with the collection of more images that better capture the variety of species that may co-occur with C. polykrikoides in the region.

Further refinement is also expected to enable discrimination of different C. polykrikoides cells types including vegetative and sexual forms, automatically and in real time, so that farmers can factor this information into decisions regarding nursery movements and other mitigation actions.

Environmental Monitoring App

In addition to the installation of the IFCB adjacent to Ward Aquafarms’ nursery systems, Ward Aquafarms has built a custom nursery monitoring and alert system, which measures chlorophyll, dissolved oxygen, water temperature, and flow rate for each system (YSI EXO3 sonde). With the suite of environmental factors provided by the YSI sonde in addition to the information provided by the IFCB, Ward Aquafarms can identify when a HAB is happening, shut off the nursery pumps, and monitor the water quality of the nursery system until the bloom has subsided. The nursery monitoring system and will alert the user if a given parameter has dropped below a user-specified threshold.

Due to the fact that the IFCB records the full diversity of phytoplankton within its 10-100 μm target size range, the sensor is also invaluable for monitoring other HAB species as well. A prime example is Pseudo-nitzschia spp., a group of diatoms that produce domoic acid, a toxin that causes amnesic shellfish poisoning when cells and/or their toxins are concentrated in shellfish meats. While toxic Pseudo-nitzschia blooms are well established threats in maritime Canada and along the U.S. west coast, it is only in recent years that the blooms have endangered New England shellfish resources, causing fall and winter closures and two shellfish recalls in Maine and precautionary harvest closures in Massachusetts and Rhode Island in 2016 and 2017.

Sources:

Anderson, D.M., Hoagland, P., Kaoru, Y. and White, A.W. 2000. Estimated annual economic impacts from harmful algal blooms (HABs) in the United States. WHOI-2000-11. Department of Biology, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts.

Garate-Lizarraga, I., Lopez-Cortes, D.J., Bustillos-Guzman, J.J., Hernandez-Sandoval, F. 2003. Blooms of Cochlodinium polykrikoides (Gymnodiniaceae) in the Gulf of California, Mexico. Revista de Biologia Tropical. 52(1):51-58.

Gobler, C.J., Berry, D.L., Anderson, O.R., Burson, A., Koch, F., Rodgers, B.S., Moore, L.K., Goleski, J.A., Allam, B., Bowser, P., Tang, Y., and Nuzzi, R. 2008. Characterization, dynamics, and ecological impacts of harmful Cochlodinium polykrikoides blooms on eastern Long Island, NY, USA. Harmful Algae. 7:293-307.

Hoagland, P., Anderson, D.M., Kaoru, Y., and White, A.W. 2002. The economic effects of harmful algal blooms in the United States: estimates, assessment issues, and information needs. Estuaries and Coasts. 25(4):819-837.

Jeong, H.J., Kim, J.S., Yoo, Y.D., Kim, S.T., Song, J.Y., Kim, T.H., Seong, K.A., Kang, N.S., Kim, M.S., Kim, J.H., Kim, S., Ryu, J., Lee, H.M., and Yih, W.H. 2008. Control of the harmful alga Cochlodinium polykrikoides by the naked ciliate Strombidinopsis jeokjo in mesocosm enclosures. Harmful Algae. 7: 368-77.

Kim, D.W., Jo, Y.H., Choi, J.K., Choi, J.G., Bi, H. 2016. Physical processes leading to the development of an anomalously large Cochlodinium polykrikoides bloom in the East sea/Japan sea. Harmful Algae. 55: 250-258.

Lee, Y.S., Lee, S.Y. 2006. Factors affecting outbreaks of Cochlodinium polykrikoidesblooms in coastal areas of Korea. Marine Pollution Bulletin. 52, 5:626-634.

O’Neil, J.M., Davis, T.W., Burford, M.A., Gobler, C.J. 2012.The rise of harmful cyanobacteria blooms: The potential roles of eutrophication and climate change. Harmful Algae. 14:313-334.

Park, T.G., Lim, W.A., Park, Y.T., Lee, C.K., Jeong, H.J. 2013. Economic impact, management and mitigation  of red tides in Korea. Harmful Algae. 30, 1: 131-143.

Park, B.S., Kim, J.H., Kim, J.H., Gobler, C.J., Baek, S.H., Han, M.S. 2015. Dynamics of bacterial community structure during blooms of Cochlodinium polykrikoides (Gymnodiniales, Dinophyceae) in Korean coastal waters. Harmful Algae. 48: 44-54.

Rountos, K.J., Tang, Y.Z., Cerrato, R.M., Gobler, C.J., and Pikitch, E.K. 2014. Toxicity of the harmful dinoflagellate Cochlodinium polykrikoides to early life stages of three estuarine forage fish. Marine Ecology Progress Series. 505:81-94.

Tang, D.L., Kawamura, H., Doan-Nhu, H., Takahashi, W. 2004. Remote sensing oceanography of a harmful algal bloom off the coast of southeastern Vietnam. Journal of Geophysical Research.

Tang, Y.Z. and Gobler, C.J. 2008. Characterization of the toxicity of Cochlodinium polykrikoides isolates from Northeast US estuaries to finfish and shellfish. Harmful Algae. 8:454-462.

Tang, Y.Z. and Gobler, C.J. 2009. Cochlodinium polykrikoides blooms and clonal isolates from the northwest Atlantic coast cause rapid mortality in larvae of multiple bivalve species. Marine Biology. 156:2601-261

ANTIFOULING/ANTIPREDATOR GEAR COATING RESEARCH

Biofouling is an especially serious issue in shellfish aquaculture, as it reduces water flow, can hurt the aesthetic value of a cultured product, and results in higher labor costs overall to deal with the fouling. Biofouling can clog the mesh of the gear in which the shellfish are grown, thereby restricting water flow, which means reduced oxygen and microalgae (food) delivery, directly reducing the growth and survival of cultured organisms. As a result, biofouling mitigation may account for as much as ~15% of total annual operating costs for shellfish growers in the US, with total costs exceeding $21 million.

Preventing or reducing biofouling is one of the most pressing concerns for a shellfish farmer. There are many ways which have been proposed to deal with biofouling, though the best method would be to stop the fouling communities from ever becoming established. One method to reduce the settlement of member of the biofouling community is the use of biofoul-releasing non-toxic gear coatings. Biofoul releasing coating in shellfish aquaculture must be non-toxic to the shellfish, but have potential to reduce biofouling and larval settlement of biofouling community memebers by creating a slippery surface or by releasing compounds which deter or prevent settlement. Netminder (East Falmouth, MA) is a biodegradable, non-toxic, gear coating pt that has shown success in reducing biofouling on cages and nets in various aquaculture operations.

Ward Aquafarms has partnered Netminder since 2015. The first experiment conducted by Ward Aquafarms and Netminder investigated the efficacy of Netminder in preventing the settlement of biofouling community members on silos in oyster upweller systems. The results were very promising (see below image), with gear coated in Netminder revealing almost no settlement compared to gear which had no Netminder applied.

In 2017, Ward Aquafarms applied Netminder to gear housing bay scallops during an multi-month experiment which investigated if Netminder could be used as a technique to mitigate the prevalence of parasites of bay scallops.

Although Netminder appeared to have no impact on the settlement of parasites on bay scallops housed in gear coated in Netminder, the gear which was coated in Netminder has a significantly lower accumulation of biofouling (kg).

Netminder as a technique for predator avoidance in oyster aquaculture:

Results from this study will aid in the development of techniques to mitigate predation of starfish and oyster drill snails on cultured eastern oysters. Eastern oysters are a sessile invertebrate, meaning they are immobile and unable to move away from potential predators, such as starfish and oyster drill snails. Although much of the gear used in oyster aquaculture keeps oysters from being directly in the sediment, portions of the gear typically extend to the sediment, such as legs on cages or rebar racks in intertidal aquaculture. With oyster aquaculture gear extending to the sediment, organisms such as starfish and oyster drills are able to climb to the location of shellfish, such as oysters, housed in said gear. Since starfish and oyster drills typically have to come into contact with gear prior to having access to forage on aquacultured oysters, identify a gear coating that deters starfish and oyster drills will help decrease oyster mortality and increase production. Results from this study illustrate multiple coatings that could help in reducing predation by starfish and oyster drills on eastern oysters housed in aquaculture gear.

To test different experimental coating developed by ePaint, including Netminder, Ward Aquafarms ran two separate experiments. The fist experiment investigated if oyster drills were attracted or deterred by a gear coating when introduced to a mesocosm with gear coated in single experimental coating.

This objective was investigated using replicate 20 liter mesocosms filled with seawater which were equipped with air stones to provide oxygenation for the duration of each 24 hour trial. All trials were maintained at water temperature of approximately 20 degrees Celsius. Once the 20 liter buckets were filled, a cage with an ID number identifying the coating applied was added to each mesocosm.

Average oyster drill prevalence on cages with different gear coatings used in the 20 liter mesocosm trials did not significantly vary (GLM-ANOVA, Chi-square, α=0.05, two-tailed, df = 10, n =88, p = 0.423, Figure 6), ranging from 22% prevalence on gear coated with Netminder to 78% prevalence on gear coated with capsaicum extract.

Average oyster drill snail abundance (average number of snails observed on a single cage) across all trials using 20 liter mesocosms ranged from 0.22 snails/cage (0 – 1 snails per cage) for cages coated in treatment Netminder to 2.0 snails/cage (0 – 5 snails per cage) for cages coated in treatment Capsaicum extract

To further investigate the efficacy of different experimental gear coatings in mitigation predation on oysters, a choice trial was conducted using a 200 liter raceway system. The 200 liter raceway tank was provided with two water pumps to provide flow and two separate air stones to provide aeration at either end of the tank. The tank was held at 20 degrees Celsius for the duration of the experiment. Prior to placement of cages, oysters, and oyster drills, the raceway tank was separated into three sections.

In each section 10 randomly selected cages with different gear coatings were placed equidistant from each other in a circular pattern. Each cage was then filled with 200 ml of 1-2” year two oysters. Within the center of the circle of cages, 50 oyster drill snails were placed. After 24 hours of exposure to the oyster drills, the number of drills on the cages and the oysters within the cages were tallied. All snails were removed from the cages and oysters and placed back in the center of the cage circle. Measurements were taken every 24 hours for four treatments.

For the oyster drill snail choice trials conducted using the 200 liter raceway system, oyster drill prevalence ranged from 0% for the control to 53% for gear coated with myrrh oil. The only treatment which had an oyster drill snail prevalence that was significantly higher than any of the other treatments was the aforementioned 53% for gear coated with myrrh oil  (GLM-TukeyHSD, Chi-square, α=0.05, two-tailed, df = 10, n =88, p = 0.0030)

Oyster drill snail abundance (average number of snails observed on a single cage) across all trials conducted in the 200 liter raceway system ranged from 0.0 snails/cage for cages coated in the control treatment group to 0.8 snails/cage (0 – 2 snails per cage) for cages coated in treatment myrrh oil

The same 200 liter raceway tank divided into three sections as used in objective three was used in objective four to test the if starfish were more attracted or deterred by different gear coatings when presented with cages housing oysters. The 200 liter raceway tank was again provided with two water pumps to provide flow and two separate air stones to provide aeration at either end of the tank and held at 20 degrees Celsius for the duration of the experiment. Prior to placement of cages, oysters, and oyster drills, the raceway tank was separated into three sections. In each section, 10 randomly selected cages with different gear coatings were placed equidistant from each other in a circular pattern. Each cage was then filled with 200 ml of 1-2” year two oysters. Within the center of the circle of cages, four 6” starfish were placed. After 24 hours of exposure of cages housing oysters to the starfish, the number of starfish touching the cage, on the cage and on the oysters within the cage were tallied. All starfish were the removed from the cages and oysters and placed back in the center of the cage circle. Measurements were taken every 24 hours for four treatments.

In the choice trials conducted with starfish in the 200 liter raceway system the prevalence of starfish on or touching a cage did not significantly vary between gear with different coatings, and ranged from 11% for menthol, silver, and zinc to 56% for treatments myrrh, hemp oil, synthetic capsaicum and capsaicum extract

Starfish abundance (average number of starfish observed on or touching a single cage) across all trials conducted in the 200 liter raceway system ranged from 0.1 starfish/cage (0 – 1 starfish per cage) for cages coated in menthol, silver, and zinc to 0.9 starfish/cage (0 – 3 starfish per cage) for cages coated in treatment myrrh oil.

Results from this study suggest that the use of gear coatings developed by ePaint may be successful in mitigating predation on aquacultured shellfish. When gear was coated with the Netminder formula, oyster drill prevalence and abundance were significantly reduced compared to other treatments. Application of Netminder on aquaculture gear which houses eastern oysters in areas where oyster drill predation is common could help increase oyster survival and the revenue of the operation. In addition to mitigating oyster drills, results from this study suggest that menthol, zinc and silver could be potential options for reducing starfish predation on aquacultured eastern oysters. Although the observed reduction in starfish prevalence on gear coated with menthol, zinc and silver was not statistically significant, coating aquaculture gear in menthol, zinc and silver could have a significant impact if applied to gear on a commercial scale. Further investigation using field trials will help to further illustrate the impact of applied gear coatings in mitigating invertebrate predation on aquacultured shellfish such as the eastern oyster.

To learn more about Netminder and other ePaint products click HERE

Sensor Development

VERIZON THINGSPACE

PROJECT DESCRIPTION:

Farming for Oysters: Ward Aquafarms, a 10 acre, 1,000 cage aquaculture farm located in Cape Cod, Massachusetts is dedicated to growing the freshest oysters possible. Verizon, in collaboration with systems manufacturer Mobotix AG, has enhanced Ward's ability to monitor the safety of its Oyster harvest-to-bag process and predict growth. Ward was able to onboard with ThingSpace and be up and running on the platform in under an hour, pulling satellite imaging data, combined with other complex data such as environmental & sub tidal water temperature, chlorophyll values, etc. to be analyzed and contextualized using Verizon Pro Services for valuable insights for Ward's aqua farming operations.

Media:
Internet of Things Article Featuring Ward Aquafarms
Verizon Press Release Featuring Ward Aquafarms

HERELAB

PROJECT DESCRIPTION:

We have partnered with HereLab on Martha’s Vineyard, to equip our farm growout area, and our nursery sites, with low-cost, real-time environmental sensors, utilizing a LoRa network. As we increase the number of sensors on the farm, we can develop a real-time understanding of temperature, dissolved oxygen, salinity, depth as well as many other aspects of the farm. Having a better understanding of our environment, will allow us to increase our productivity, improve survival and growth by modifying stocking densities, as well as helping to identify upcoming stressors on the farm such as harmful algae blooms or low dissolved oxygen events. The goal of this project is to develop the technology, and share the open-source capabilities with farms, municipalities, and other stakeholders in the coastal zone that would like to better understand our dynamic ecosystems. HereLab is a nonprofit, public good IoT organization.

We establish free to use, public wireless network for IoT devices for sensors, actuators & communications applications. HereLab is part systems architect and part social change agency. As systems architect, we design and structure pilots and deployments around an integrated approach to data design, retrieval and publication. As social change organization we bind this integrated approach to local educational, organizational, municipal and business concerns. We use LoRaWAN technologies (long range, low power, long battery life), to enable researchers, environmentalists, municipalities, entrepreneurs and students to make and deploy sensors. Our nonproprietary services include sensor design, network provisioning, data storage, analysis and web-based visualization. We believe open, real-time and historical data (for built space, social and natural environments) can give all constituents and community members tools and processes for greater social awareness and increased civic responsibility.

LoRaWAN is an emerging standard embraced by many technology and communications companies, large and small. It enables two-way, low power requirement, Long Range (LoRa) wide area networks (WAN) based on gateways which look similar to a home WiFi gateway, but that offer line of sight communication ranges up to several kilometers, including through buildings. LoRa communications are optimized for small packet transmissions (and not, for instance, streaming video), enabling theoretically more than 3,000 nodes to be serviced by one gateway. The gateways are connected to the internet via local ethernet connection or cellular modem, and can be powered by local 120V plugs or solar arrays. Node radios in the field can be easily connected to sensors and actuators, and programmed for operating cycles to be very energy efficient. For example, a sensor array attached to a radio and microprocessor might be programmed to spend 99% of its time “sleeping” in low energy mode, and then “wake” on regular intervals to take measurements, send data to the LoRaWAN gateway, and then return to sleep. Thus, multiple sensors could be run for very long periods of time (1 year or more) on small, low cost, easily available batteries. For security, LoRaWAN communications send information in encrypted channels between node and gateway, and then can employ a variety of enhanced security methods for transmission to communications brokers or storage over the internet. Once to the internet, data from a number of sensors can be integrated with other data sources to facilitate powerful analytics or predictive modeling

Media:
HereLab Website
HereLab Twitter Feed