Seasonal nitrogen and phosphorus dynamics during benthic clam and suspended mussel cultivation

Effects of a commercial, suspended eastern oyster nursery upon nutrient and sediment chemistry in a temperate, coastal embayment

“…The sediment-flux calculations, combined with the organic C:N ratios, suggest that there were local effects of the FLUPSY on the marine sediments, which is consistent with mussel aquaculture practices (i.e. long-line systems; Richard et al 2007, Nizzoli et al 2011). …”

“…Bottomand surface-water concentrations never exceeded 0.5 and 15.12 µmol l −1 , respectively, indicating that despite a large flux of total ammonia from the sediments (highest 73.46 ± 5.25 µmol m −2 h −1 ), concentrations of local dissolved total ammonia were below the EPA toxicity level not toxic to organisms within the embayment. The total ammonia flux from East Creek sediments was in the same order of magnitude as that from other estuarine and coastal marine sediments in non-aquacultured areas (Bailey 2005, Valdemarsen et al 2010, and was lower than fluxes recorded beneath aquacultured mussels and clams suspended from long lines (Nizzoli et al 2011).…”

“…The sediment flux of total ammonia near the FLUPSY was 2 to 20 times lower than at mussel aquaculture sites that had fluxes as high as 1500 µmol m −2 h −1 (Grant et al 1995, Richard et al 2007, Nizzoli et al 2011). This could be attributable to 2 reasons: (1) the bivalves are smaller in a FLUPSY compared to long lines and (2) the FLUPSY is circulating 1.32 × 10 5 l h −1 of bottom water to the surface, allowing the fecal matter that is being released by the oysters to stay in the water column longer, so it can undergo microbial degradation before settling.…”

Effects of different aquaculture methods for introduced bivalves (Hyriopsis cumingii) on seston removal and phosphorus balance at the water–sediment interface

“…In the benthic treatments, the feces and pseudofeces were buried at the sediment surface, whereas they were excreted into water in the suspended treatments, which could also explain why the concentrations of water TP and PP in the suspended treatments were significantly higher than those of the benthic treatments in our experiment (Figure 4). In addition, Nizzoli et al (2011) believe that suspended mussels, as the high sediment OM content below the mussel ropes, could stimulate heterotrophic microbial metabolism and mineralization of organic N and P. Many studies on bivalve effects showed that they can also affect nutrient cycling by many other mechanisms, such as assimilation and absorption, bioturbation of sediments through bivalve movements, oxygen depletion and others (Newell 2004;Sgro et al 2005). Vaughn and Hakenkamp (2001) posit that if bivalve biodiversity is declining and populations release more nutrients than they absorb, bivalves may serve as a nutrient source, whereas they may serve as a nutrient sink while a population is growing or if biomass is being lost from the ecosystem by export or permanent burial.…”

“…Søndergaard et al (2003Søndergaard et al ( , 2007 reported that inhibiting the release of internal P loading from the sediment pool accumulated during CONTACT Feng He hefeng@ihb.ac.cn a high P loading period has become an important factor determining the success of lake ecological restoration. Some previous studies have proved that introducing bivalves into eutrophic water could promote the release of P, thereby triggering a shift from a clear to a turbid water state (Paolo et al 2000;Nizzoli et al 2011;Zhang et al 2014). Therefore, further research on improving the seston removal effects and how to reduce the release of P loading caused by bivalves is necessary to the application of bivalve manipulation technology.…”