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Int'l Journal of Marine Science 2012, Vol.2, No.9, 62
-
69
http://ijms.sophiapublisher.com
62
Review Article Open Access
Giant Clam Aquaculture: a Review on Induced Spawning and Larval Rearing
Miguel Mies , Paulo Y.G. Sumida
Benthic Dynamics Laboratory (LDB), Department of Biological Oceanography, Oceanographic Institute, University of São Paulo. Praça do Oceanográfico,
191- 05508-120 São Paulo, SP – Brazil
Corresponding author email: miguel.mies@usp.br;
Authors
International Journal of Marine Science, 2012, Vol.2, No.9 doi: 10.5376/ijms.2012.02.0009
Received: 09 Dec., 2012
Accepted: 14 Dec., 2012
Published: 18 Dec., 2012
Copyright:
©
2012 Mies and Sumida, This is an open access article published under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article:
Mies and Sumida, 2012, Giant Clam Aquaculture: a Review on Induced Spawning and Larval Rearing, International Journal of Marine Science, Vol.2, No.9
62-69 (doi: 10.5376/ijms. 2012.02.0009)
Abstract
Giant clams are the largest extant bivalves and widespread inhabitants of the Indo-Pacific coral reefs. These organisms
are particularly sought after by the food industry because of their large mantle and adductor muscle, while also are relevant to the
aquarium trade market. The aquaculture of giant clams is dependent of a land-based hatchery divided in several tanks with different
purposes for larval rearing. Prior to reproductive events, broodstock are conditioned and gametogensis is stimulated by frequent food
additions, increased photoperiod and intense physical-chemical stability at optimum conditions. Several different methods can be
employed to induce spawning, most notoriously the intragonadal injection of serotonin, thermal stress and addition of macerated
gonadal tissue of a conspecific. The success of the method is based on spawning occurrence, time for response and events of
broodstock mortality. After spawning, gametes are fertilized and a succession of planktonic larval stages is cultured in hatching tanks
and raceways. Embryonic development lasts for approximately 12 hours until the hatch of free-swimming and non-feeding
trochophore larvae. After 24 hours post-fertilization larvae morph into veliger stage, made evident by the presence of calcium
carbonate shells and velum. Veliger larva are fed with live or preserved phytoplankton and must also acquire symbiotic zooxanthellae.
The last stage is the pediveliger stage at approximately one week post-fertilization, when settlement takes place and metamorphosis
is soon attained.
Keywords
Giant clam; Tridacna; Aquaculture; Spawning; Larval development
1 Background
1.1 Giant clams
Organisms belonging to the family Tridacnidae are
known as giant clams and represent the largest living
bivalves. The tridacnid clams are easily distinguishable
among bivalves by having a hypertrophied siphonal
mantle, which is also colourful given the fact that it
houses symbiotic dinoflagellates known as
zooxanthellae. Giant clams are distributed across the
tropical coral reefs of the Indo-Pacific, where the
water column is characterized by physical-chemical
stability. Nutrient concentrations are low, salinity
circles 34 ppt and temperature averagely ranges from
24
℃
to 30
℃
. Specimens can be found in intertidal
zones as well as in deeper offshore reefs at depths
below 30 m, often attached to consolidated substrates
or associated with hermatypic coral colonies.
The family Tridacnidae is comprised of ten species
placed in two genera,
Tridacna
and
Hippopus
. The
smallest and slowest growing species is
T
.
crocea
(Hart et al., 1998), while the largest and fastest
growing is The True Giant Clam (Beckvar, 1981),
T.
gigas
, that can reach over 130 cm in shell length
(Ruscoe, 1962). While most species are physically
similar, their identification can be easily made based
on shell morphology and mantle characteristics
(Braley, 1992; Calumpong, 1992).
1.2 Importance
There is a worldwide interest in giant clams, both as a
food source and also for ornamental purposes. The
mantle and adductor muscle are sold in many Asian
restaurants while live organisms are traded for
displaying in home and public aquaria. Larger species
such as
Tridacna gigas
and
T. derasa
are especially
sought after for their higher meat content while
T.
maxima
and
T. crocea
, which present the highest