Previous studies have demonstrated undoubtedly that the deposit feeding polychaete, Hediste diversicolor, can efficiently handle sludge from land based aquaculture by working detritus into the sediments, thereby, avoiding clumping. In a study by Bergström and his team, the growth and survival rates of H. diversicolor fed on mussel faeces was investigated. Moreover, in order to understand the consequences of experimental handlings, the effects of chemical fluxes in and out of the sediment were also evaluated.

Strong differences in growth were observed between the different treatments, though, no difference was observed in short-term survival. The polychaetes grew on average 17% in wet weight after a period of 10 days when fed only on mussel faeces, as compared to 3% when given equivalent amounts of organic matter from the natural sediments. However, an increase in growth 19–20% growth was observed when polychaetes were administered a mixture of faeces and natural sediments, thus, suggesting an approximate additive effect of the two food sources. Chemical analysis showed that irrespective of the origin, the oxygen consumption increases with the load of organic material; higher fluxes of ammonia was caused by faecal material as compared to natural organic material. However, neither oxygen consumption nor nutrient fluxes were affected by the ashing of sediments. On the contrary, increased fluxes of silicate was observed as a consequence of ashing but were not affected by the addition of mussel faeces. Therefore, regardless of the experimental artefacts owing to ashing of sediments, this study showed that oxygen and nutrient dynamics responded accordingly to the manipulations of organic material and not to the potential alterations of the sediment composition. Hence, the observed effects on the growth of H. diversicolor can be manifested as due to differences in quality and amount of organic material administered. In fact, mussel faeces turned out to be is a high-quality food source for H. diversicolor. Furthermore, with sufficient data from previous studies in connection to bioturbation, the authors conclude H. diversicolor to be a potential candidate in further efforts to develop practical elucidations based on bioturbation for mitigation of adverse effects on benthic environments associated with mussel-farming.

For details please visit: Biodeposits from Mytilus edulis: a potentially high-quality food source for the polychaete, Hediste diversicolor