Hydrobiologia 298: 295-305, 1995.
D. Belk, H. J. Dumont & G. Maier (eds), Studies on Large Branchiopod Biology and Aquaculture II.
© 1995 Kluwer Academic Publishers.
295
Life history, resting egg formation, and hatching may explain the
temporal-geographical distribution of Artemia strains in the
Mediterranean basin
Carlos Barata, Francisco Hontoria & Francisco Amat
Instituto de Acuicultura de Torre de la Sal (Consejo Superior Investigaciones Cient[jicas), I2 595 Ribera de
Cabanes, Castellon, Spain
Key words: life history, resting eggs, succession, zooplankton, Artemia, reproduction, lifespan, encystment
Abstract
Life history traits are presented for the sexual species (Artemia tunisiana) and for parthenogenetic diploid and
tetraploid strains A. parthenogenetica reared at 15 °,24 ° and 29.5 °c.
In laboratory cultures, we present evidence that the seasonal appearance of the sexual Artemia tunisiana (the
dominant winter-spring population), and of two parthenogenetic populations of Artemia (the dominant springsummer populations) in certain Spanish saltworks is controlled by temperature through its effect on reproductive
and survival traits. Minimum and maximum reproductive output and survival for the sexual and parthenogenetic
populations, respectively, occurred at a typical temperature (24 0q of the late-spring season when the sexual
population is replaced by parthenogenetic forms. Furthermore, the high production and hatchability of cysts from
the sexual population at low temperatures (15 0q, and of the parthenogenetic populations at middle temperature
(24 0q, indicate the role of dormancy as an adaptation regulating seasonal occurrence.
Introduction
The mechanisms responsible for the seasonal patterns
in the composition of mixed Artemia populations are
poorly understood. This is due to a scarcity of studies, and to the difficulty in obtaining information on
reproductive and lifespan parameters.
A review of the geographic distribution of sexual
and parthenogenetic popUlations of Artemia is necessary to understanding the design of our laboratory
experiments. In the Old World, the genus Artemia consists of a number of sibling species that can be divided
into a sexual diploid group and an obligate parthenogenetic complex composed of diploid and polyploid
individuals (Browne & Bowen, 1991; Lenz & Browne,
1991, Zhang & Lefcort, 1991; Browne, 1992).Artemia
parthenogenetica is the most common form and sexual populations are found in relatively few habitats
(Browne & MacDonald, 1982). Polyploid Artemia
populations are more frequent at lower and higher latitudes ( <25 ON and >40 ON) than in temperated regions
(Zhang & Lefcort, 1991). It is likely that these correspond with high and low temperature habitats.
Parthenogenetic and sexual forms, as well as individuals of different ploidy, have been reported to
co-occur in many Artemia populations (Amat, 1980,
1983; Amat et aI., 1991; Takami, 1989; Barigozzi,
1989; Zhang & Fengqi, 1989). However, field data
are available for only two Spanish sites (Amat, 1983)
and for lake Urmia (Iran) (Takami, 1989). At these
localities, temporal partitioning occurs, the sexual
species dominate in winter when temperature is low,
while the parthenogenetic species prevails in summer.
Such partitioning was expected, based on laboratorydetermined temperature profiles (Vanhaecke et aI.,
1984; Browne et at., 1988, 1991; Browne, 1992;
Zhang & King, 1993). These authors found that
changes in temperature can have major effects on survival and life-history traits in the sexual and parthenogenetic diploid populations. In general, the Old World
sexual popUlations are cold-adapted while parthenogenetic diploids show broader temperature tolerance,
D. Belk, H. J. Dumont & G. Maier (eds), Studies on Large Branchiopod Biology and Aquaculture II.
© 1995 Kluwer Academic Publishers.
295
Life history, resting egg formation, and hatching may explain the
temporal-geographical distribution of Artemia strains in the
Mediterranean basin
Carlos Barata, Francisco Hontoria & Francisco Amat
Instituto de Acuicultura de Torre de la Sal (Consejo Superior Investigaciones Cient[jicas), I2 595 Ribera de
Cabanes, Castellon, Spain
Key words: life history, resting eggs, succession, zooplankton, Artemia, reproduction, lifespan, encystment
Abstract
Life history traits are presented for the sexual species (Artemia tunisiana) and for parthenogenetic diploid and
tetraploid strains A. parthenogenetica reared at 15 °,24 ° and 29.5 °c.
In laboratory cultures, we present evidence that the seasonal appearance of the sexual Artemia tunisiana (the
dominant winter-spring population), and of two parthenogenetic populations of Artemia (the dominant springsummer populations) in certain Spanish saltworks is controlled by temperature through its effect on reproductive
and survival traits. Minimum and maximum reproductive output and survival for the sexual and parthenogenetic
populations, respectively, occurred at a typical temperature (24 0q of the late-spring season when the sexual
population is replaced by parthenogenetic forms. Furthermore, the high production and hatchability of cysts from
the sexual population at low temperatures (15 0q, and of the parthenogenetic populations at middle temperature
(24 0q, indicate the role of dormancy as an adaptation regulating seasonal occurrence.
Introduction
The mechanisms responsible for the seasonal patterns
in the composition of mixed Artemia populations are
poorly understood. This is due to a scarcity of studies, and to the difficulty in obtaining information on
reproductive and lifespan parameters.
A review of the geographic distribution of sexual
and parthenogenetic popUlations of Artemia is necessary to understanding the design of our laboratory
experiments. In the Old World, the genus Artemia consists of a number of sibling species that can be divided
into a sexual diploid group and an obligate parthenogenetic complex composed of diploid and polyploid
individuals (Browne & Bowen, 1991; Lenz & Browne,
1991, Zhang & Lefcort, 1991; Browne, 1992).Artemia
parthenogenetica is the most common form and sexual populations are found in relatively few habitats
(Browne & MacDonald, 1982). Polyploid Artemia
populations are more frequent at lower and higher latitudes ( <25 ON and >40 ON) than in temperated regions
(Zhang & Lefcort, 1991). It is likely that these correspond with high and low temperature habitats.
Parthenogenetic and sexual forms, as well as individuals of different ploidy, have been reported to
co-occur in many Artemia populations (Amat, 1980,
1983; Amat et aI., 1991; Takami, 1989; Barigozzi,
1989; Zhang & Fengqi, 1989). However, field data
are available for only two Spanish sites (Amat, 1983)
and for lake Urmia (Iran) (Takami, 1989). At these
localities, temporal partitioning occurs, the sexual
species dominate in winter when temperature is low,
while the parthenogenetic species prevails in summer.
Such partitioning was expected, based on laboratorydetermined temperature profiles (Vanhaecke et aI.,
1984; Browne et at., 1988, 1991; Browne, 1992;
Zhang & King, 1993). These authors found that
changes in temperature can have major effects on survival and life-history traits in the sexual and parthenogenetic diploid populations. In general, the Old World
sexual popUlations are cold-adapted while parthenogenetic diploids show broader temperature tolerance,