BIOREMEDIATION POTENTIAL OF Alitta brandti (POLYCHAETE) TO UTILIZE NUTRIENT-RICH EFFLUENT FROM A MARINE RECIRCULATING SYSTEM

Aquaculture produces excess amounts of waste discharge and utilizes large amounts of raw materials that potentially limit industry growth. The industry relies heavily on marine resources, mainly fish meal and fish oil, for use in formulated feeds. A strategy to increase resource efficiency in aquaculture is to utilize untapped waste streams to produce additional biomass from nutrient rich effluent, as well as those by-products from other feed industries. Deposit-feeding polychaete worms, Alitta brandti could be beneficial for waste bioremediation. The goal of this study is to evaluate if marine polychaetes can aid in the bioremediation of nutrients produced from the effluent of Sablefish, Anoplopoma fimbria.

An 8-week feed trial was conducted in a recirculating aquaculture system where individual worms of three different initial size classes (Weight Range: Small 0.2-1.8g, Medium 1.8-6.8g, Large 7-18g) were fed one of two effluent types ("Wet" or "Dry") or a pelleted commercial control by Tetramin® ("Pellet"). A second experiment was conducted for a 4-week trial (initial worm sizes 0.1-2.5g) in which the wet effluent was enriched with either, feather, blood, or soybean meal, with additional supplementation of an additive Schizochytrium spp. and canola oil, or the pellet control.

After 8 weeks, the worms fed the control diet grew significantly larger (P < 0.05) than both effluent diets, although size was a significant factor (Figure 1). After 4 weeks, worms fed the soybean-enriched effluent grew significantly higher (P < 0.05) compared to the control (Figure 2). Our work suggests that A. brandti does have the ability to consume such effluents however, sufficient nutrient uptake is observed when effluents are supplemented with additional meal byproducts.