11 Similarities between Microbial and Periphytic Biofilms in Aquaculture Systems

Abstract:

Generally, periphyton refers to the'assemblage of attached aquatic plants and animals on submerged substrates, including associated nonattached fauna'(van Dam et al., 2002). The principal components of the periphyton assemblage are the attached organisms, which form a living mat. These mats have a lot in common with the biofilms used in recirculating aquaculture for biofiltration. In this chapter, the latter are further referred to as' biofilms' or'biofilters' to distinguish them from'periphyton mats'. The principal tasks of biofilters in recirculating aquaculture systems (RAS) are the removal of non-settleable organic matter, dissolved organic matter and total ammonia (Bovendeur et al., 1987). Biofilters are built as compact as possible, mostly indoors, where space is costly. Contrary to periphyton-based aquaculture systems, grazing by culture organisms is not a goal of biofilter design. Due to the compact and mostly closed design little or no light penetrates the biofilter, so very few or no algae are present in biofilms compared with periphyton mats. An exception is the development of heterotrophic micro-dinoflagellates in indoor marine trickling filters (van Herrewaarden, H., Zeeland Fish Farm. 2004. personal communication). In contrast, Azim et al.(2002a) found that between 29 and 64% of the organic matter in periphyton mats growing on bamboo poles in ponds in Bangladesh were algae, the remainder of the periphyton mat consisting of heterotrophic organisms, including heterotrophic bacteria, protozoa and micro-metazoa. The same heterotrophic organisms are also found in biofilms (Timmons et al., 2002). Zero-exchange active suspension ponds are …

Año de publicación:

2005

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