Biofouling is a 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 of prevention is to deploy aquaculture material at times or in locations (e.g., greater depths, different geographic areas) where less settlement of fouling organisms occurs.
As of 2015, at Ward Aquafarms, LLC, there are many fouling organisms which are causing issues (aside from predators such as sea stars (Asterias spp.) or oyster drills (Urosalpinx cinerea):
Various types of seaweed attach at different times of the year dependant on depth and water temperature. While fairly innocuous on gear with larger mesh size (>3/4”), on smaller mesh sizes (<1/2”), the seaweed can significantly clog the mesh, and severely reduce water flow (Fig.1)
The most common being the Acorn barnacle (Semibalanus balanoides), through many other species are common (Semibalanus spp.). These organisms reduce flow and add weight to the cages, are extremely difficult to remove from the gear once they have settled, and contribute to reduced value on the cultured shellfish due to a decrease in aesthetic quality.
Tube worms (various calciferous tube worms from the Spionidae family, especially Streblospio benedicti).
Tube worms form calciferous tubes both on the gear and on the cultured shellfish, both of which are extremely difficult to remove or kill once they have settled. They feed on the same food as oysters, and therefore both reduce flow through clogging mesh, and reduce food by competing for the same resources. They also reduce value on the cultured shellfish due to a decrease in aesthetic quality.
Boring sponge (Cliona spp.).
While the boring sponge does not foul the gear, and does not restrict flow, it has the potential to be far more destructive. The boring sponge will typically colonize the area of an oyster near the hinge. This makes the oyster unsellable, and impossible to shuck for a consumer. Therefore, this is a fouling organism or critical concern, which must be monitored for and managed.
Once these fouling organisms become established, removal or destruction requires considerable effort. Various methods have been used to remove biofouling including hand removal and mechanical removal (pressure washing, tumbling, rotating bags, and others), but all are laborious, time consuming, and expensive.
Fig 1. — Seaweed on one of the cages at Ward Aquafarms, LLC in 2015. The fouling on this cage made from ¾” mesh is so dense that it completely restricts water flow on many of the meshes. This cage was deployed in January 2015 and hauled to the surface in July 2015.
The research plan for the 2015 season was three-fold, focusing on all three stages of the oyster culture cycle: nursery (months 1-3), intermediate growout (months 3-12), and final growout (months 12-30).
Evaluate NETMINDER coatings on oyster nursery silos in terms of survival, growth and regular labor required to maintain the upweller.
Investigate the impact of NETMINDER on growth and survival of post-nursery oysters in small-mesh (1/2”) bottom-gear.
Investigate the impact of NETMINDER on growth and survival of 1 year old oysters, utilizing larger (3/4”) mesh bottom-gear.
5/8” mesh ADPI oyster bags coated with NETMINDER before initial setting; stocked with oysters.
Temperature and Light Profile:
Dissolved Oxygen Profile:
Conductivity and Salinity Profile:
2016 Research Plan:
Scallops: Ward Aquafarms, LLC has been growing bay scallops since 2014, and the production is increasing again this year. There has been no work at Ward Aquafarms, LLC on bay scallops, and the same or modified experiments as in the current work could be replicated for bay scallops to investigate the impact of NETMINDER on different species at different life stages.
Floating gear: Floating gear fouls far faster than gear at depth, and evaluating the same oyster stocking densities, with a higher fouling load may lead to significant benefits to utilizing NETMINDER.
Different depths: In the current trial, the gear was all deployed at 8-10’. Future work should systematically evaluate the impact of NETMINDER on shellfish growth and survival, in reference to different fouling loads over a range of depths. This will allow the researchers to evaluate depths of efficacy, given certain light levels with certain levels of turbidity.
Different gear types: Scallop farming requires lantern nets, clams are grown in bags, and different gear types and different species will perform in NETMINDER-coated gear differently.
Light: It will be important in future work to correlate all results with light levels in the field, in order to determine the optimal depth, and light level to activate NETMINDER and realize significant results.
Labor: Perhaps the most important potential reason to use NETMINDER on the gear at a commercial oyster farm, would be in a reduction or elimination of the need to pressure wash 2-4 times per year. Looking into reusing gear over a longer time period, and eliminating labor costs should be a primary focus of future work. Simultaneously, long term trials can be conducted with large mesh gear, which may lead to the conclusion that with NETMINDER coating, larger mesh cages may only need to be cleaned once annually.
Upweller Silos Before
Upweller Silos After
USDA Bay Scallops
Expanding sustainable shellfish aquaculture: Optimizing growth and survival in a bay scallop nursery system
Project period: April 1, 2016 - December 31, 2016
The bay scallop (Argopecten irradians), an Atlantic marine bivalve found in coastal New England waters, which has historically supported a significant fishery. However, since the 1980’s the commercial fishery has been in decline due to losses in nursery habitat (eelgrass beds), overfishing and coastal water quality degradation. Bay scallops are a high value, sustainable product which require very similar growing techniques to shellfish that are currently cultured, such as oysters and clams. Shellfish farmers throughout New England are seek complementary species to grow in order to diversify risk and increase revenue. Additionally, expanding shellfish aquaculture will provide excellent ecosystem benefits by increasing water clarity and reducing impacts of eutrophication. However, bay scallop culture techniques are still rudimentary, and efficiency could be significantly improved if further investigations were done on new technology and aquaculture methods. In 2015, Ward Aquafarms constructed a pilot-scale nursery system utilizing a unique floating downweller design which significantly improved growth and survival as compared to existing bay scallop nursery systems. We propose to investigate differences in growth, survival, and food availability in relation to flow rates, initial stocking densities and mesh sizes. The results of the proposed project will allow Ward Aquafarms, in conjunction with Cape Cod Cooperative Extension to make recommendations to farmers and resource managers throughout New England on how best to farm bay scallops to expand jobs for shellfish farmers while promoting sustainable farming techniques.
(left) Floating downweller with 6 silos; (middle) 6 stacked trays holding bay scallops prior to being put into the downweller silo; (right) bay scallops at day 30 (starting size 750µm).
USDA Harmful Algae
Daniel Ward PhD Department of Biological and Environmental Science University of Rhode Island
Dr. Sandra E. Shumway Research Professor Department of Marine Sciences University of Connecticut
Challenge Area and/or Foundational Program Area: NIFA Fellowships Grant Program Global Food Security; Animal health and production and animal products
Expansion of US aquaculture will result in promotion of a healthy, nutritious, sustainable food source for a growing global population. Shellfish aquaculture in particular, has seen strong growth in recent years due to standardized culture techniques, reliable seed sources, and strong stakeholder support due to the environmentally benign nature of shellfish farming. Bivalve aquaculturists throughout southern New England however, have been confronted with a devastating harmful algae problem due to the dinoflagellate Cochlodinium polykrikoides. This harmful algal bloom (HAB) species was not detected anywhere in the region prior to 2005, though the now annual blooms have caused widespread and remarkable biological and economic losses throughout the shellfish aquaculture industry. Even though farmers have noted losses which restrict economic viability and growth in the industry, the rapid emergence of the HAB species in the region has meant no comprehensive monitoring program, and very little research on the effects on commercially important cultured species. The proposed project will expand upon agricultural knowledge of impacts of Cochlodinium polykrikoides on species cultured in New England, while investigating potential mitigation strategies. It is imperative that sustainable mitigation strategies are both investigated and implemented as the ecosystem continues to change in order to continue to provide healthy, nutritious seafood to consumers throughout the US.
CCEDC Bay Scallops
Optimizing sustainable bay scallop growout strategies
Cape Cod Economic Development Council
On Cape Cod, the oyster and clam farming industry is well established, providing sustainable jobs and consistent revenue to the region. Many shellfish farmers are would like to expand and diversify their crop, in order to reduce risk and increase output. The bay scallop (Argopecten irradians), has historically supported a large fishery in the Cape Cod region, though the population rapidly declined in the 1980’s due to significant losses in essential nursery habitat, as well as overfishing and the degradation of coastal waters. Bay scallops grow to market size much quicker as compared to oysters and clams, which currently dominate the region’s aquaculture operations. Bay scallops are filter feeders, and therefore simply by growing them they naturally increase water clarity and decrease microalgae in the water column. Bay scallops are already in high demand, with low supply available due to the decimated wild population, they are a very valuable crop (as much as $25/ lb. to the fisherman), and given that they already exist naturally in the Cape Cod waters, culturing them in the same areas holds significant promise.
The first step in growing any shellfish is to source seed from a hatchery, and high quality bay scallop seed is currently available from the Aquaculture Research Corporation in Dennis, at a size of approximately 1 mm. The second step is to grow the shellfish to approximately 1 in. in a nursery system, and until recently no nursery system existed for bay scallops. In 2015, Ward Aquafarms designed and implemented a floating downweller system which was based on the oyster nursery concept of a floating upweller. The nursery system generated high survival, and fast growth rates, and therefore bay scallop seed could be grown to 1 in. within 30 days. The third step is to grow the shellfish to market size in gear at a growout site, and until recently, the available methods resulted in limited success. In 2014 and 2015 Ward Aquafarms, LLC grew scallops in ½” vinyl-coated wire-mesh cages, and achieved both high growth throughout the fall, and high survival over the winter. However, the proper stocking density, effect of depth, effect of oxygen concentrations, and other environmental variables which differ between farms is unknown.
Optimizing growout techniques will allow Cape Cod farmers to grow a scallops to a size big enough for the live market in the fall of the first year, or if the farmer chooses, a larger, hardier scallop to overwinter and sell in year two, or both. Ward Aquafarms is proposing to investigate different cage, net, and bag growout techniques in different aquaculture environments. The results will be communicated to fellow shellfish farmers on Cape Cod, with the intent of building a new industry which will expand on the success of oyster aquaculture. The expansion of shellfish aquaculture to incorporate bay scallops will not only benefit farm owners, the job market, as well as the economy, but will also provide ecological services improving water clarity and reducing coastal eutrophication on Cape Cod.
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.
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