Effect of Different Filter Methods on Seawater Quality at a Marine Scallop Hatchery

Abstract

The effect of using two different filtering methods in the main seawater inlet to a scallop (Pecten maximus) hatchery in Norway was tested. Seawater was filtered through active filter media (AFM) and a protein skimmer, or through a drum filter and a protein skimmer. Seawater quality was characterized and tested on algal growth rate, egg development and larval activity. Tests were performed under winter and spring conditions (March, April and May 2009). Both seawater treatments reduced the dissolved organic carbon concentrations in the inlet seawater. The total bacterial number was stable in both seawater treatments, except for an increase in the drum filter in March. The bacterial community showed seasonal development: Actinobacteria and Alphaproteobacteria dominated in March, while Gammaproteobacteria dominated in April and May. In a cluster analysis, samples from both seawater treatments showed high similarity on similar sampling dates. Vibrio spp. occurred, but was never observed in seawater coming from the skimmer after the drum filter. This sampling point was often clustered as most similar to the incoming seawater.

Comparative study of the culturable microbiota present in two different rearing systems, flow‐through system (FTS) and recirculation system (RAS), in a great scallop hatchery

“…Due to their character of filter feeders, the microbiota of shellfish is strongly influenced by the environment in which they live (Beleneva, Zhukova, & Maslennikova, 2003;Cavallo, Acquaviva, & Stabili, 2008;Ortigosa, Garay, & Pujalte, 1995;Pujalte, Ortigosa, Macián, & Garay, 1999;Sugita, Tanaami, Kobashi, & Deguchi, 1981). Thus, in a hatchery we can find that the microorganisms present in the water tank are also present in animals, so the quality of inlet water in the plant and the distinct filtration systems can make a substantial difference from a microbiological point of view (Magnesen, Jacobsen, & Moepi, 2013;Skjermo & Vadstein, 1999). Feeding with microalgae is another input of bacteria in the system despite the efforts focused on the maintenance of axenic cultures of phytoplankton.…”