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Add To Calendar 24/02/2016 12:00:0024/02/2016 12:20:00America/ChicagoAquaculture 2016MACROALGAE AS AN ENRICHMENT FEED FOR WHITE WORMS Enchytraeus albidus Champagne 3The World Aquaculture Societyjohnc@was.orgfalseanrl65yqlzh3g1q0dme13067DD/MM/YYYY


Michelle L. Walsh* and Marcel Hatter
Florida Keys Community College
Key West, FL 33040

White worms Enchytraeus albidus are an attractive live feed for juvenile and small-mouthed organisms. Their prolonged survival in the full salinity spectrum of most natural waters (0-40 ppt) has made them popular among aquarium hobbyists, especially as a conditioning diet for ornamental broodstock. White worms have a high protein (70-75% by dry wt) and lipid (15% by dry wt) content with relatively low levels of ash (6% by dry wt). They are a good source of n-3 long chain polyunsaturated fatty acids, though the DHA content may be limiting. We investigated the feasiblity of replacing a portion of the worms' standard culture feed (baker's yeast) with local marine macroalgae species as a strategy to potentially increase worm n-3 long chain polyunsaturated fatty acid content.  In this preliminary study, we monitored total biomass over time for worms fed a diet of: (1) 100% yeast; (2) 100% algae; (3) 50% yeast: 50% algae; (4) 75% yeast: 25% algae. Each treatment consisted of 5 replicates.

Experimental containers were 10 cm dia x 7.5 cm ht and filled with 4 oz of organic potting soil. Each experimental container was provided with ½ teaspoon of feed total. For these initial trials, we utilized the green alga Caulerpa sertularioides. Algae was collected from the wild, rinsed, dried, and ground into a fine powder. For mixed feed treatments, algae and yeast were mixed together before being dispensed to an experimental container. Once feed was dispersed, each container received 10 adult white worms (~2 cm in length). Once each month, for 3 months, all worms were harvested and the total biomass of worms per container was recorded. Worms were then returned to their respective experimental containers.

We quickly learned that yeast activity in these small, closed containers necessitated better aeration as mortality in the 100% yeast treatments increased with increasing worm density. After month 1, mesh vents were added to all container lids to allow off-gassing of CO2 emitted by the active yeast. Worm biomass in the 100% algae treatments was poor, and worms did not ever appear to finish their allotted feed each month. The 75% yeast: 25% algae treatment had the highest biomass at the end of trials (p < 0.05), followed by the 50% yeast: 50% algae treatment.

Future work will repeat trials with other local species of marine algae such as the red algae Dasya baillouviana or Eucheuma isiforme. Once a macroalgae that can sustain worm biomass levels similar to that of the standard feed can be identified, nutritional analyses of the macroalgae, as well as worms reared on the macroalgae, will be conducted.

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