438
J. Iglesias and L. Fuentes
for 1-month-old paralarvae. On the other hand, Moxica et al. (2006) and Viciano
et al. (2011), working with 1,000 L tanks and using enriched Artemia (cultured with
Isochrysis sp. and further enriched with Nannochloropsis sp.), obtained dry weights
of 1.76 mg and 1.88 mg, respectively, for the same-aged paralarvae.
23.4.3 Physical and Chemical Culture Parameters
23.4.3.1 Water Circulation
Stagnant water is commonly used for the first week to maintain a green-water
system; thereafter, some authors exchange water for 4 h day
−1
, corresponding to a
100 % day
−1
renewal rate (Iglesias et al. 2007; Viciano et al. 2011), whereas others
recommend maintaining a constant water flow to give an exchange rate of at least
150 % day
−1
(De Wolf et al. 2011). The water inlet should produce a mild tangential
circulation of the surface water. However, both lateral and centrally bottom-placed
water outlets have been used by some investigators.
In order to obtain a homogeneous distribution of paralarvae and live prey in the
culture tanks, gentle aeration can be supplied by air stones (Iglesias et al. 2004;
Okumura et al. 2005) or open tube aeration can be done (De Wolf et al. 2011).
Currents that result in the accumulation of paralarvae in very small areas should be
avoided.
It is also important to prevent the production of small air bubbles that can be
trapped in the paralarvae mantle. For this reason, special devices for the distribution
of the incoming water, such as multiple superficial inlets (Villanueva 1995) or bottom
water inlets combined with a superficial water outlet (Carrasco et al. 2005, 2006),
have been used. Nevertheless, the use of a high water flow can increase the risk of skin
damage and arm erosion, resulting in an increased mortality of the paralarvae (Vidal
et al. 2002).
23.4.3.2 Light
A wide range of light conditions (natural light, incandescent bulbs, fluorescent
tubes) has been used in paralarval culture. Optimal light conditions seem to depend
on the type of tanks that are used. In general, higher light intensities and longer
photoperiods are used in black tanks than in light-coloured tanks or white-bottom
tanks. Surface light intensity in the rearing tank should be 500–700 Lx when using black tanks (Iglesias and Fuentes 2013), whereas other authors recommend
using lower light intensities (60–250 Lx for a 14 h L (light):10 h D (dark) photoperiod) in black-walled and white-bottom tanks (De Wolf et al. 2011). Garrido et al.
(2012) studied the effect of different types of lighting on the growth and survival
of O� vulgaris paralarvae.
J. Iglesias and L. Fuentes
for 1-month-old paralarvae. On the other hand, Moxica et al. (2006) and Viciano
et al. (2011), working with 1,000 L tanks and using enriched Artemia (cultured with
Isochrysis sp. and further enriched with Nannochloropsis sp.), obtained dry weights
of 1.76 mg and 1.88 mg, respectively, for the same-aged paralarvae.
23.4.3 Physical and Chemical Culture Parameters
23.4.3.1 Water Circulation
Stagnant water is commonly used for the first week to maintain a green-water
system; thereafter, some authors exchange water for 4 h day
−1
, corresponding to a
100 % day
−1
renewal rate (Iglesias et al. 2007; Viciano et al. 2011), whereas others
recommend maintaining a constant water flow to give an exchange rate of at least
150 % day
−1
(De Wolf et al. 2011). The water inlet should produce a mild tangential
circulation of the surface water. However, both lateral and centrally bottom-placed
water outlets have been used by some investigators.
In order to obtain a homogeneous distribution of paralarvae and live prey in the
culture tanks, gentle aeration can be supplied by air stones (Iglesias et al. 2004;
Okumura et al. 2005) or open tube aeration can be done (De Wolf et al. 2011).
Currents that result in the accumulation of paralarvae in very small areas should be
avoided.
It is also important to prevent the production of small air bubbles that can be
trapped in the paralarvae mantle. For this reason, special devices for the distribution
of the incoming water, such as multiple superficial inlets (Villanueva 1995) or bottom
water inlets combined with a superficial water outlet (Carrasco et al. 2005, 2006),
have been used. Nevertheless, the use of a high water flow can increase the risk of skin
damage and arm erosion, resulting in an increased mortality of the paralarvae (Vidal
et al. 2002).
23.4.3.2 Light
A wide range of light conditions (natural light, incandescent bulbs, fluorescent
tubes) has been used in paralarval culture. Optimal light conditions seem to depend
on the type of tanks that are used. In general, higher light intensities and longer
photoperiods are used in black tanks than in light-coloured tanks or white-bottom
tanks. Surface light intensity in the rearing tank should be 500–700 Lx when using black tanks (Iglesias and Fuentes 2013), whereas other authors recommend
using lower light intensities (60–250 Lx for a 14 h L (light):10 h D (dark) photoperiod) in black-walled and white-bottom tanks (De Wolf et al. 2011). Garrido et al.
(2012) studied the effect of different types of lighting on the growth and survival
of O� vulgaris paralarvae.