The interaction between shellfish culture and ecosystem processes

Abstract

The carrying capacity of the Oosterschelde ecosystem for the production of mussels (Mytilus edulis) was evaluated before and after completion of a large-scale coastal engineering project in 1987. This project caused hydrodynamic and water-quality changes; hence, phytoplankton-species composition changed and phytoplankton turnover increased, but primary production remained the same. In the prebarrier period (1980–1986), condition of mussels showed a significant negative correlation with the annual shellfish standing stock and a significant positive correlation with the annual primary production. The system was exploited at maximum capacity. In the postbarrier period (1987–1997), the significant correlation between mussel condition and primary production remained, but there was no longer a negative correlation between standing stock and condition. This indicates overstocking, but yields were maintained. This was explained by (i) feedbacks of the mussels in the Oosterschelde ecosystem—through their large filtration and nitrogen-regeneration capacity, increased phytoplankton turnover was induced; and (ii) adaptation to the new conditions by the shellfish farmers in their management of the mussel stocks. It was concluded that feedbacks by filter feeders and farmers have to be addressed in estimating the exploitation capacity of ecosystems.

Mathematical modelling to assess the carrying capacity for multi-species culture within coastal waters

“…It is also important to consider the impact of bivalve cultivation itself on water quality, sediment composition and ecosystem functioning. By recycling nitrogen, bivalves may stimulate primary productivity (Smaal et al, 2001). For the same reasons, in line with the concept of ecological aquaculture, bivalves may be successfully cultured alongside kelp, when nutrients excreted and egested by the bivalves may be absorbed by macroalgae and recycled into valuable biomass .…”

“…These include the bay of Marénnes-Óleron (France), where oyster (Crassostrea gigas) growth has reduced significantly with increased stock densities over the years (Raillard and Ménesguen, 1994). Similarly, mussel (Mytilus edulis) growth in the Oosterschelde estuary (The Netherlands) has been compromised by increased standing stocks (Smaal et al, 2001).…”

Sources and export of nutrients associated with integrated multi-trophic aquaculture in Sanggou Bay, China

“…The resulting increased light penetration can potentially enhance the production of benthic plants (Newell & Koch 2004). If high levels of dissolved inorganic nitrogen (DIN) regenerated by bivalves are sufficient to allow the relatively slowgrowing nanoplankton to grow fast enough to overcome grazer control, primary production can be stimulated through recycling of nitrogen (Smaal et al 2001). Some marine IMTA systems have been commercially successful at industrial scales, especially in Asia (China) (Troell et al 2009).…”

Draagkracht voor schelpdieren : definities, indices en case studie

“…Er is meer licht voor de primaire productie want het water is helderder geworden. In de periode tot 1995 is de primaire productie op peil gebleven (Smaal et al, 2001). Dit wordt onder meer toegeschreven aan de invloed van de filter feeders die zorgden voor voldoende interne recycling van nutriënten (Prins & Smaal, 1994;Smaal et al, 2001).…”