Environmental Engineering Reference
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loses more energy through ammonia excretion than E. megalocyathus , suggesting different
physiological mechanisms for using the ingested protein (Table 4).
R 2
a
b
Oxygen consumption, mgO 2 h -1 animal -1
Enteroctopus megalociathus
0.2
0.71
0.82
Octopus maya
0.93
0.69
0.93
Ammonia excretion, mgN-NH 3 h -1 animal -1
Enteroctopus megalociathus
0.32
0.37
0.53
Octopus maya
0.75
0.43
0.76
Ingestion rate, g day -1 animal -1
Enteroctopus megalociathus 0.19 0.67 0.95
Octopus maya 0.07 0.82 0.95
Table 4. Equation parameters (Y = a W b ) of oxygen consumption, ammonia excretion and
ingestion rate of Enteroctopus megalociathus and O. maya . (Data from Farías et al., 2009).
4. Ecophysiology of crustacean
Between crustacean shrimp, crab and lobster has been deeply studied from an
ecophysiological point of view. Crustaceans live in a wide variety of environments
including fresh water, salty water and sea water. Crustaceans can be finding in holes in
earth living with a little bit of humidity or in the crown of palms, several meters above the
ground. Crustacean aquaculture has been growing in the last decades being the shrimp
culture the most important activity. The world production of crustaceans was 5 million tons
in 2008 being shrimp culture 73.3% of the total production (FAO, 2011). Today the white leg
shrimp Litopenaeus vannamei is the most important species for aquaculture. Litopenaeus
vannamei was introduced in China where its cultivation shifted to that of Penaeus monodon.
Ecophysiological studies of shrimp have been important to define culture environments
mainly when this species is mostly cultivated in salty water, where joint with diluted
environment, animals are exposed to high temperatures, wide oxygen variations and
nitrogen waste products.
4.1 Effect of salinity on shrimp physiological condition
White shrimp, Litopenaeus vannamei , the most cultivated shrimp species in America, grows
well at salinities ranging from freshwater to hyper saline waters. Although L. vannamei
tolerates broad salinity ranges, values for optimal growth have not yet been determined,
and studies up to date show contradictory results. Whilst studies conducted under
laboratory conditions have shown that maximal growth occurs between 5 and 15 UPS (Bray
et al .( 1994); Boyd, 1995; Rosas et al . , 2001a), other studies have reported maximal growth at
salinities above 35 UPS (Ponce-Palafox et al . , 1997; Decamp et al . , 2003). Recent studies have
demonstrated a close relationship between nutrition and environmental characteristics at
which shrimp are cultivated. This is because dietary levels of carbohydrates, lipids and
proteins largely determine the shrimps capacity to respond to changes in the ionic
composition of culture water.
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