1. Establish a Project Guidance Committee comprised of NYSG outreach specialists, shellfish farmers, NGOs, and environmental and health managers to guide project goals and information dissemination, 2. To assess the ability of cultivable macroalgae including summer seaweeds Porphyra spp. and Gracilaria tikvahiae, and the winter species, Saccharina latissimi (sugar kelp) and Chondrus crispus (Irish moss), to inhibit the growth of HAB species common to NY waters: A. catenella, C. polykrikoides, Dinophysis acuminata, P. minimum, and A. anophagefferens. 3. To assess the effects of macroalgae on HABs and shellfish in ecosystem-based mesocosm experiments. 4. To customize field cultivation techniques and assess the feasibility of co-culturing HAB-combative seaweeds with bivalve shellfish at commercially viable scales on Long Island shellfish farms. 5. To evaluate the effects of farming HAB-combative seaweeds on: a) bivalve survivorship, growth, and toxin accumulation, b) localized water quality (i.e. pH, DO, nutrient concentrations, HAB densities, phytoplankton species composition), and c) nutrient bioextraction. 6. Develop and disseminate seaweed cultivation best practices and guidance materials for the protection of ecosystems and aquaculture.

1. Establish a Project Guidance Committee comprised of NYSG outreach specialists, shellfish farmers, NGOs, and environmental and health managers to guide project goals and information dissemination, 2. Perform laboratory experiments assess the ability of cultivable macroalgae including summer seaweeds, Porphyra spp. and G. tikvahiae, and the winter species, S. latissimi and C. crispus to inhibit the growth of HAB species common to NY waters: A. catenella, C. polykrikoides, Dinophysis acuminata, P. minimum, and A. anophagefferens. 3. Perform field mescosm experiments assess the ability of cultivable macroalgae including summer seaweeds Porphyra spp. and G. tikvahiae, and the winter species S. latissimi and C. crispus to inhibit the growth of HAB species common to NY waters. 4. Perform field mescosm experiments that assess the effects of macroalgae on aquacultured resources (shellfish) in an ecosystem-based setting. 5. Integrate HAB-combative macroalgae into oyster farms to assess the feasibility and nutrient bioextraction potential of co-farming seaweeds and bivalves in Long Island estuaries, 6. To measure the localized impacts of seaweed farming on water quality and bivalve growth, survivorship, and toxin content. 7. Develop and disseminate seaweed cultivation best practices and guidance materials for the protection of ecosystems and aquaculture.

New York’s coastal waters have experienced an intensification of anthropogenic nutrient loading that has contributed toward a multitude of serious and diverse harmful algal blooms (HABs) during the past several decades that have had severe ecosystem and economic consequences. Macroalgae are a group of autotrophs which, like HABs, are also promoted by nutrient loading. Historically, studies from Asia have demonstrated that many species of macroalgae can inhibit the growth of, and potentially lyse, a broad range of microalgae, including multiple HAB species. Recently, we have demonstrated that some macroalgae commonly found in NY estuaries, including Porphyra spp., Saccharina latissimi, and Ulva spp., are capable of lysing or strongly inhibiting the growth of the major HAB species that plague NY’s estuaries, including A. catenella, A. anophagefferens, C. polykrikoides, and P. minimum. Beyond nutrient reduction, within an ecosystem setting macroalgae may inhibit HABs by increasing pH and/or alleleopathy. Many aspects of macroalgae make them an attractive option for the prevention, control, and mitigation of HABs. Macroalgae are a natural component of estuaries and thus do not involve the introduction of a non-native species or chemicals to coastal ecosystems. Further, there is a great precedent for the purposeful deployment of macroalgae in estuaries often as a part of integrated aquaculture whereby macroalgae are cultivated and harvested in parallel with shellfish or fish. Many macroalgae species also have high economic value, making the integrated aquaculture approach profit neutral or generating for farmers. The Gobler Lab has recently optimized methods for the open water aquaculture of both summer (Gracilaria) and winter (Saccharina; kelp) crops of macroalgae. This project will create an opportunity to both (1) expand the scope of the NY aquaculture industry, and (2) introduce a cost-effective method for mitigating damage to aquacultured seafood from HABs.