Settling velocity and total ammonia nitrogen leaching from commercial feed and faecal pellets of gilthead seabream (Sparus aurataL. 1758) and seabass (Dicentrarchus labraxL. 1758)

Abstract

Settling velocity and total ammonia nitrogen leaching from commercial feed and faecal 50Several studies under laboratory conditions reported that 250-300 g kg -1 of ingested food is 51 voided as faeces (Butz and Vens-Cappell, 1982). Just as with food losses, a continuous 52 4 improvement in diet elaboration has led to a gradual reduction of faecal discharges to about 53 100-250 g kg -1 of ingested food (Cho et al., 1994; Talbot and Hole, 1994 Watling, 1994; Elberizon and Kelly, 1998; Chen et al., 1999a,b; Chen et al., 2003) MRAs for feed pellets (Table 3) showed that water temperature and pellet density had no (Table 5). Constant k was significantly higher at 25 ºC (P < 0.05) and in smaller feed pellets 215 (P < 0.05), while t a was significantly larger at 15 ºC (P < 0.05) but also for smaller pellets (P 216 < 0.05) ( 246The influence of pellet weight was also identified by other authors (Elberizon and Kelly, 247 1998; Chen et al. 1999b, Sutherland et al., 2006. In this study, we not only found that initial 248 pellet size determined settling velocity but also, unlike Chen et al. (1999b) authors state, the range of parameters studied was not so critical to the settling velocity. 270Despite this, we observed greater but non significant settling velocities at low temperature, as 271 Chen et al. (1999b) noted. These authors suggested that this could be due to the influence of 272 temperature on pellet density, although in our experiments we found that seawater 273 temperature did not affect pellet density.

Total ammonia nitrogen leaching from feed pellets used in salmon aquaculture

“…Leaching rates of feed pellets as they sink have received less attention and very few works deal with this topic: see Phillips et al. (1993) on salmonids, Piedecausa et al. (2009) on Mediterranean cultured fish and Fernández‐Jover et al.…”

Life Cycle Assessment of Gilthead Seabream (Sparus aurata) Production in Offshore Fish Farms

“…In fact, some companies have a platform or feed silo boats and mechanized distribution systems, although no generalized control systems. After consultation with several producers in the same study area [71], feed loss was estimated to be 5%-10% of the food provided in seabream farms. Our consultations with producers provided higher values of around 15%.…”

Modeling the benthic loading of particulate wastes from a gilthead seabream (Sparus aurata) farm during a complete rearing cycle

“…Las partículas de alimento no consumido caen aproximadamente 3 veces más rápido que las partículas fecales (Gowen et al 1989), pues las velocidades de sedimentación son entre 6 y 14 cm s -1 para partículas de alimento (Panchang et al 1997, Doglioli et al 2004, Vassallo et al 2006, Piedecausa et al 2009), y entre 0.05 y 7.5 cm s -1 para partículas fecales (Panchang et al 1997, Doglioli et al 2004, Piedecausa et al 2009). Con base en estos estudios, las velocidades de sedimentación consideradas en este documento…”

“…Uneaten feed settles about 3 times faster than fecal pellets (Gowen et al 1989), with settling velocities between 6 and 14 cm s -1 for food pellets (Panchang et al 1997, Doglioli et al 2004, Vassallo et al 2006, Piedecausa et al 2009), and ranging from 0.05 to 7.5 cm s -1 for particulate feces (Panchang et al 1997, Doglioli et al 2004, Piedecausa et al 2009). Based on these studies, the settling velocities considered herein were 10 cm s -1 for excess feed and 2 cm s -1 for fecal pellets throughout the entire simulation.…”