Population dynamics of the hymenosomatid crab Elamnopsis kempi in a brackish subtidal region of Basrah, Iraq
Malik H. Ali, Salman D. Salman, A.Y. Al-Adhub

The population biology of the subtidal crab Elamenopsis kempi (Chopra & Das) in the Garmat-Ali region of the Shatt Al-Arab River System at Basrah, Iraq was investigated, in the period from 16th March 1987 to 15th February 1989. Population density in this area ranged from 150 ind.m-2 ± 22.75 SE to 1310 ind.m-2 ± 54.1 SE. No significant relation between water temperature and density of the species was noticed. The breeding season extended from April to November or December. The life span of the summer cohorts may be 4-8 months while the overwintering cohorts may live for 9-1 1 months. Sexual maturity of females may be attained at a size of 3.2 mm C.L. Males may achieve maturity at 3.9 mm C.L. Cohorts with shorter life span may achieve sexual maturity in 1-2 months after settlement, while those with a longer life span may do so in about 6-8 months. The incubation period in the field may extend to 35 days. In the laboratory, the incubation period ranged from 12 to 23 days depending on temperature. Egg size at the first stage of development was 0.356 mm. Fecundity is a function of size, and varied from 90 to 463 eggs. Several life history strategies are implicated by this species to compensate for low fecundity: 1. Maximum care of the brood, as the eggs are incubated in an internal cavity and not externally. 2. High percentage of ovigerous females which may be, in certain times, about 90% of mature females. 3. Production of multiple broods (9.6-10.5) during one breeding season. Rate of mortality was lower amongst the overwintering cohorts than the summer cohorts. Summer cohorts have a growth rate of 0.021 mm d-1 and the overwintering cohorts grew at 0.0 15 mm d-1.

Keywords: opulation biology, growth, Hymenosomatidae, crab Elamenopsis kempi, Shatt AI-Arab, Iraq.
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