Integrated multi-trophic aquaculture systems with periphyton: cleaning and feeding

Dr. Suzanne Boxman, former graduate student and Recliam social media team member, is currently a Postdoctoral researcher in Eilat, Israel. The following is a summary of her research project and progress so far.

Eilat North Beach shorline

Eilat, Israel, north beach shoreline

Sunny Eilat is Israel’s resort town. Full of hotels, shoreline, and excellent diving, Eilat is the perfect getaway location. It is also an ideal location to study sustainable aquaculture systems as it is home to the National Center for Maricutlure (NCM). This national research facility conducts research on new methods for rearing high-value aquatic animal and plants species.

Seaweed and sea urchin grown at NCM.

Seaweed and sea urchin grown at NCM.

Beginning in the mid 1990’s NCM conducted pioneering research on integrated-multi trophic aquaculture (IMTA). The novel aquaculture system design produces not only fish, it also produces seaweeds on the nutrient rich effluents from the fish tanks. Eventually the system expanded to include additional species including bivalves and sea urchins. The seaweeds grow rapidly while simultaneously removing excess ammonia from effluents. A product on their own, the seaweeds can also be fed to bivalves or sea urchins thereby contributing to production of a third product.

The research has since progressed and current work is focused on the production of periphyton on the effluents instead of or in conjunction with the seaweed. Periphyton is a conglomeration of microscopic and macroscopic organisms including heterotrophic microbes, diatoms, algae, and cyanobacteria. Naturally present in most aquatic ecosystems it serves as an important food source for invertebrates and fish.

Thin layer of periphyton on net. This is an example of the artificial nets being used to grow the periphyton.

Thin layer of periphyton on net. This is an example of the artificial nets being used to grow the periphyton.

Considering its role in nature as a food source, current research at NCM is exploring the potential to use the periphyton first as a biofilter then, to use the periphyton as a supplemental fish feed. Preliminary research indicates the periphyton is rich in protein and carbohydrates. It is also effective at removing ammonia from effluents with up to 80% ammonia removal achieved.

Developing sustainable aquaculture feeds is one of the aquaculture industries’ biggest challenges. Periphyton has great potential to offset processed feed requirements while simultaneously providing water treatment in closed or semi-closed systems. Using periphyton to clean aquaculture wastewater is a perfect exampling of reclaiming nutrients and putting them to a better use.

For more information about Dr. Boxman’s experiences in Israel you can also check out her personal blog about living abroad at https://hereforthehummus.wordpress.com/

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