Effect of shellfish culture on phytodetritus vertical fluxes in tropical waters - southern Brazil

. Abstract: Mussel culture is an expanding activity in shalIow and sheltered bays along the coast of Santa Catarina, southern Brazil. Although mussel culture generates benefits, several environmental impacts are associated with this kind of activity. Its success depends on. factors which include the environmental impact and the carrying capacity of the system. One conspicuous effect of mussel culture is the enhancement of vertical particle flux to the botiom sediment and depletion of water column phytoplankton biomass. Phytodetritus vertical fluxes was evaluated in a mussel culture area by collecting particles with sediment traps and analysing plant pigment by high performance liquid chromatography (RF-HPLC). Results showed that mussel culture, in average, enhances almost 5 times the vertical phytodetritus flux as compared to the reference site. Pheophorbide like pigments were the main chlorophyll-a degradation products collected by the traps. Given the high phytodetritus production, compared to the low water column phytoplankton biomass observed, it is suggested that allocthonous phytoplankton advected to the cultured area is an important process to sustain the mussel growth in the area.