Therefore an overload of organic material will have adverse effects on organisms present in the water. As well as oxygen depletion, the addition of large quantities of organic material can displace nutrients present in the water which the mussel feeds on when it filters the water (Maier et al., 2000). The reduction of available nutrients, as well as oxygen availability, was more likely the cause of the closure observed in these trials. As more organic compounds were added, an increase in the percentage of mussels effected would be expected. The average duration of closure of the mussels can also be explained through the lens of organic water pollution. Mussels that close as a result of a reduction in water quality will do so due to a lack of available oxygen and nutrients. A nutrient starved mussel, such as the ones used in these trials, may open to reassess the conditions of their surroundings, before closing again when they realize conditions have not improved. This was observed in the experiment, and can be seen in the sporadic nature of the length of closure results during the powder trials. These observations strongly suggest the closure is the result of water pollution by organic material overload.