Recipient Organization
FLORIDA DEPARTMENT OF AGRICULTURE AND CONSUMER SERVICES
407 SOUTH CALHOUN ST.,
TALLAHASSEE,FL 32399
Performing Department
Agriculture and Consumer Serv.
Non Technical Summary
The shellfish aquaculture industry has been expanding throughout the U.S. and Gulf of Mexico in recent decades. Beyond shellfish farms' important role in increasing national seafood production, the industry supports rural coastal communities by providing employment opportunities. Shellfish farms also provide environmental benefits like improving water quality and clarity, removing excess nutrients, and providing critical nursery habitat to a variety of other marine animals.When farming hard clams, cover nets are used in some areas to prevent excessive crop losses from predation. However, cover nets are also the most frequently lost or abandoned type of shellfish aquaculture gear and have the potential to become marine debris and cause environmental damage. In addition, while a vast majority of marine debris comes from land-based sources, the portion attributed to aquaculture gear threatens the reputation of this sustainable industry. Cost-effective solutions to environmental and public perception issues will play a key role in the future of the shellfish aquaculture industry in the United States.One potential solution for aquaculture debris is manufacturing gear from biodegradable materials. This project will directly lead to the creation of a new biodegradable material that can be used for clam cover nets, ultimately reducing coastal plastic pollution and enhancing economic efficiency, sustainabilityand public perception of the shellfish aquaculture industry. The new material will be made from lignin, a paper manufacturing waste product generated at a rate of 50 billion tons per year. Clam cover nets will be constructed from this new lignin-based material, and testedfor strength, durabilityand performance in a real-world field experiment on clam leases in Cedar Key, Florida. Results will be compiled and made available through websites, publicationsand workshops for the public, clam farmers, state and national aquaculture associations, and manufacturing facilities that may be interested in producing clam nets from this new biodegradable material. There is also potential for this marine biodegradable material to be used in coastal and ocean restoration efforts, like those for reef and shorelines, and as a replacement for plastics in other shellfish aquaculture production methods. While shellfish aquaculture is already renowned for its superlative sustainability and environmental benefits, reducing the industry's dependence on plastics through biodegradable alternatives will reduce environmental impacts, create economic opportunities to expand and intensify production, and further improve shellfish aquaculture's public image as a steward of the nation's coastal ecosystems.
Animal Health Component
45%
Research Effort Categories
Basic
10%
Applied
45%
Developmental
45%
Goals / Objectives
Major goals of this project include reducing a source of plastic pollution from the coastal marine environment and providing a solution for aquaculture debris that willsupport public acceptance of aquaculture practices and enhance sustainability of the industry.Marine debris is a growing problem worldwide that has recently commanded interest and urgency within scientific and consumer communities alike.The greatest contributor of plastic debris to the marine environment is trash from land-based sources. Yet, commercial fishery and aquaculture industries have received considerable criticism for loss or abandonment of gear made with synthetic materials. In Florida, clam cover net is by far the most abundant and problematic aquaculture debris.While the efforts of the Florida Department of Agriculture and Consumer Services (FDACS), University of Florida Institute ofFood and Agricultural Sciences (UF/IFAS),and the Cedar Key Aquaculture Association (CKAA) have improved gear management practices and disposal compliance in the area, cover nets are still lost periodically due to storms or inadequate anchoring, and net debris continues to accumulate in the local environment. It is clear that a novel and permanent solution to this issue warrants investigation. This project proposes a permanent solution to this debris issue through the development and eventual commercial production of a novel clam cover net material which is as functional as current polypropylene nets but also biodegradable in a marine environment.Tomeet these goals, the current project will: 1) develop a novelbiodegradable polymer composed of an underutilized paper manufacturing byproduct, lignin, generated at a rate of 50 billion tons annually and not commercially important to food or other industries; 2) manufacture clam cover nets from this new polymer, designed for a lifespan of 12-14 months in the marine environment;and 3) test the resultant materialfor strength, durability and performance in a real-world field experiment on clam leases in Cedar Key, Florida. Results of this project will be compiled and made available to the public, shellfish farmers, and manufacturing facilities that may be interested in mass producing clam nets from this new biodegradable material.
Project Methods
A. Laboratory SynthesisThis project will utilize a novel polymer for consideration as a biodegradable material for manufacturing clam cover netting. The new material isa lignin and castor oil-based polyethylene terephthalate (PET) analog polymer synthesized using raw materials that do not have food value,exhibit biodegradability, are sufficiently durable to complete a period of clam growth to market size, are strong and flexible enough to perform comparably to traditional clam nets, and are cost effective to produce. The new polymer material uses natural lignin productsproduced in large volumes as a waste product in commercial paper manufacturing.Once the polymer is prepared from its lignin and castor oil precursors, the precise measurement of basic mechanical and thermal properties will be essential in establishing structure-property relationships.Basic mechanical properties includingYoung's modulus, maximum tensile strength, strain at break and energy-to-break will be measured with atensile tester. Overall thermal properties of the polymer will be evaluated by differential scanning calorimetry and thermogravimetric analysis. Themechanical and thermal properties of the biodegradable net match those of standard polypropylene manufarturing equipment, increasing the likelihood of commerical adoption.The synthesized polymers will be processed by extrusion to make fibers for experimental clam nets. The extrusion process will make the polymer molecule chains orient (aligned chains), which will enhance strength and toughness of the bulk polymer.Mechanical and thermal properties of the produced fiber will be tested (as above) to understand the effect of high-pressure extrusion on final fiber properties. Thefibers will be used to make experimental clam nets by partially melting fiber cross points together to make square shape holes, thus forming a net. The dimensions and size of the experimental net will replicateconventional nets used throughout the industry (i.e., 2-mm thick with 1.5-cm x 2.5-cm square holes).Before field trials, polymer degradation will be simulated in the lab using a commercial photoreactor, which will produce appropriate UV range wavelengths. Within the photoreactor, the polymer sample will be held in average salinity, temperature and mechanical forcing conditions experienced at the field sites.During the test period, changes inmechanical properties, molecular weight, mass and color will be measured over time with atensile tester,gel permeation chromatography,balance andCCD camera, respectively. The time of the lab test can then be converted to approximate time in the field.B. Field ExperimentsFollowing material synthesis and lab testing, a field experiment will be conducted to examine the performance of the biodegradable net in real-world conditions at two different sites in Cedar Key, Florida. The primary experimental site will be UF/IFAS's 8-acre management agreement, which has been used for clam aquaculture studies for more than a decade. The research site is in ahighly productivearea on the southeast side of Cedar Key. An additional site will be located at a commercial lease site located on the northwest side of Cedar Key. This site has been selected by the industry and CKAA board of directors due to substantial differences in conditions compared with the UF/IFAS management agreement site.At each site, a total of three treatments will be examined: clam bags with no cover net (control), clam bags covered with traditionalpolypropylene netting and clam bags covered with the experimental biodegradable netting. For each of the three treatments, nine replicate 9-mm mesh polyester "growout bags" (n=27 bags per site, N=54 bags total) will be stocked with growout-sized seed clams (12-15 mm standard length; SL) at a standard density (1,150 clams/bag) following standard culture protocols. Three growout bagsof each treatment will be "belted" together (connected with cable ties) for a total of three "belts" per treatment at each site. One of each treatment beltwill be placed in a row (i.e., ablocked design) and the belts within each row will be randomly assigned. Belts will be planted directly on the bottom and secured with PVC stakes. All clams stocked in field trials will be from the same cohort, of the same age and of the same relative size.During growout, a single row of treatmentbelts will be sampled from each site at months 4, 8 and 12to measure clam production characteristics (total live, length, width and live (total) weight). These bags will not be replanted after sampling as the disturbance can have a negative effect on production. Production characteristics will be analyzed using standard statistical tests with a randomizedblocked design (i.e., Chi-square, ANOVA, Tukey's HSD post-hoc test) after testing data for underlying data assumptions. All tests will use an alpha of 0.05 for significance. The field experiments will be terminated after 12 months, which is the typical time required to reach a marketable size of 50-mm SL. The biodegradable net material is being designed to degrade within 12-14 months, as requested by the stakeholders.To gather net degradation and strength characteristics, additional net pieces will be submerged off a dock near UF/IFAS's research site. Net samples 150-cm2in size will be collected monthly and shipped to PI Chung's lab to measure mechanical properties (see above) using a tensile tester. Once the field experiment is complete, any remaining netting will be assessed for degradation state and tensile strength.Net performance and degradation can then be assessed across time and used to further refine the net's chemical structure. Alternative lab synthesis strategies will be used as needed to address potential material deficiencies identified during field trials.Water quality parameters (temperature, salinity, dissolved oxygen and turbidity) will be measured every 30 minutes throughout the experiment duration at monitoring stations consisting of YSI 6600 sondes, adjacent to the field sites. HOBO® temperature data loggers will also be placed inside growout bags, sampled quarterly.Water quality data will be analyzed using an existing protocol that checks for errors due to fouling or sonde malfunction and then posted to the UF/IFAS Shellfish Extension website.C. Efforts and EvaluationProduction of the new material and experimental results will have broad appeal and applicability. Project results will be shared with both local stakeholders and the U.S. shellfish aquaculture industry at-large through various industry associations and research communication channels. The new material composition will be shared with commercial net producers in the U.S. to identify a company interested in large-scale production. For the academic community, we anticipate publication of the polymer synthesis methods and field experiment results in academic journals and presentation of results at scientific meetings.Building upon similar past activities hosted by FDACSand UF/IFAS Shellfish Extension, results will be shared with clam farmersviaworkshops, online, and technical publications. FDACS will produce a fact sheet publication aimed at clam farmers relating the results of the project (to be hosted online free to the public and disseminated at various events). Results will also be summarized and posted on the FDACS Division of Aquaculture and UF/IFAS Shellfish Extension websites, free to the public. Results will further be shared with key stakeholders in Cedar Key through meetings with the CKAA and Cedar Key Chamber of Commerce.The Division of Aquaculture will continue regular communications with the Cedar Key clam aquaculture industry and associations and produce a long-term project impact report one year after the project's conclusion to gauge user adoption rates and the economic viability of the biodegradable nets.