Blue Remediation (FS052)

Project Outcome:

Blue Remediation’s concept has been proven during the feasibility study (FS052). The Scottish sea cucumber Holothuria forskali survived feeding on a mixture composed of salmon waste (salmon faeces + extra pellets) and mud during the 58 days of the laboratory experiment. The sea cucumbers showed more appetite and an increased satiety for the diet containing salmon waste compared to the control mud diet. H. forskali also spent less time and energy foraging for food during the night when their diet contained salmon waste, which is encouraging for the prospect of retaining sea cucumbers under aquaculture pens. 

In parallel, a combination of laboratory measurements was implemented into a computer model to represent numerically the physiological processes of sea cucumber. Our model was able to reproduce literature results as well as the results observed during the lab experiment (e.g., the average growth rate). Preliminary results showed that sea cucumbers may remove up to 70% of waste in targeted areas below aquaculture pens. This shows the high potential of sea cucumber to clean the seabed, while allowing other species to survive the current anoxic condition below cages. Re-establishing a higher species diversity on the seabed may have a snowball effect on breaking down aquaculture waste below cages. 

Beyond proving the feasibility of the concept, the FS has also highlighted the need of studying the relationship between the physiological parameters and environmental variation (e.g., water temperature) to provide an accurate long-term prediction of the aquaculture waste absorption of sea cucumbers.