Effects of sand sediment and
vertical surfaces (AquaMatsTM) on production, water quality, and
microbial ecology in an intensive Litopenaeus vannamei culture system
D. Bratvold, C.L. Browdy-2001
Aquaculture, 195 (1-2): 81-94
Abstract:
Growth and production of Pacific white shrimp (Litopenaeus
vannamei) was examined along with water quality, and general indicators
of microbial activity in replicate intensive tank cultures with no sediment,
sand sediment, and sand sediment together with additional vertical surfaces
(sand/mat). All treatments received similar feed and fertilizer input. An
initial linear shrimp growth rate was relatively high (1.65 g/week) in all
treatments. A reduction in growth rates was seen in the no-sediment and sand
treatments, while linear growth continued longer in the sand/mat treatment.
Shrimp weight, survival and production was significantly greater in the
sand/mat treatment than in the sand and no-sediment treatments. While the
latter two treatments yielded similar production, the no-sediment treatment
required weekly additions of soda ash during the last month of the 104-day
season to maintain a minimum pH of 7.0. Significantly higher pH, in
conjunction with lower phytoplankton biomass and ammonia in the sand/mat
treatment than in the sand treatment suggests greater carbon fixation by the
attached algal community of the sand/mat treatment. This is further
supported by similar carbon mineralization rates in all treatments as
roughly indicated by water respiration rates in conjunction with greater
sludge accumulation in the sand/mat treatment. Phyto and bacterioplankton
levels were significantly lower in the sand/mat treatment than in the other
treatments. Ammonia, nitrate and sludge accumulation were similar in the
no-sediment and sand tanks. The sand/mat treatment had significantly greater
nitrite than the other treatments. Water column nitrification rates were
similar in the sand and no-sediment treatments and significantly greater in
the sand/mat treatment, suggesting that nutrient cycling rates may be
greater in this treatment. From a production standpoint, the primary
difference in the no-sediment and sand treatments was the need for proactive
management of pH in the no-sediment tanks. The quantity of vertical surface
area addition tested in the sand/mat treatment of this study yielded higher
shrimp production in conjunction with significant differences in water
quality and indicators of general activity, suggesting that this relatively
high level of vertical surface addition may significantly affect aquaculture
production systems.
(Waddell Mariculture Center, South Carolina
Department of Natural Resources, PO Box 809, Bluffton, SC 29910 USA, Tel.:
+1-843-837-3795 ext. 149; fax: +1-843-837-3487, E-mail:
bratvold@musc.edu)