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Vol. 45 No. 4, 2006
Postembryonic Growth, Development and Reproduction of Gammarus aequicauda (Martynov, 1931) (Gammaridae) in Laboratory Culture
Ermelinda Prato*, Francesca Biandolino, and Christian Scardicchio
CNR - Institute for Coastal Marine Environment, Section of Taranto, Via Roma 3, 74100 Taranto, Italy
Ermelinda Prato, Francesca Biandolino, and Christian Scardicchio (2006) Gammarus aequicauda
(Martynov, 1931) (Gammaridae) is an epibenthic amphipod very well
adapted to life in estuaries and shallow coastal waters. In Mar Piccolo
in Taranto, Italy, it is the most abundant macrofaunal species of
soft-bottom communities. The life history of G. aequicauda
was analyzed in laboratory culture under controlled conditions of 18°C
and a salinity of 36 in order to assess postembryonic growth,
development, and reproduction. Pairs of amphipods in precopula were
observed daily until the female was found to be ovigerous. The
fecundity was estimated as the number of juveniles released by each
female. Juveniles produced in the laboratory were transferred to new
aquaria, and at an interval time of 7 d, the head length was measured,
the antennal segments were counted, and the sexual maturation stage was
assessed. The mean time spent in precopula ranged 1-3 d and embryonic
development ranged 5-8 d. The head length of newly born G. aequicauda
was approximately 0.23 mm (0.1 mg dry weight), and the head reached a
maximum length of about 1.8 mm (11.85 mg) after 140 d. There was a
significant correlation between head length and the number of articles
on the 1st antennae. A positive correlation between the number of
juveniles and the size of G. aequicauda
females (in terms of head length) was also observed. Females produced
at least 3 consecutive broods with a mean offspring number of 19.3 ±
13.3. Males were on average larger than females. The sex of the males
could be determined at an age of 30-37 d, and the 1st precopula was
observed after 40 d. The increase in egg volume during development was
not significant (p > 0.05).
Growth continued throughout life under laboratory conditions. One
important feature of this study was to provide the essential basis for
the development of laboratory toxicity tests with cultured animals.
There are several advantages of using laboratory cultured populations:
the individuals are close to a normal physiological state, they are
capable of growing and reproducing in captivity; and the animals are of
known ages and are available throughout the year.
Key words: Gammaridean amphipod, Life cycle, Laboratory culture.
*Correspondence: E-mail:linda.prato@iamc.cnr.it
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