The series of reproductive events in various species of Gammaridae can be described as precopula, copula, egg deposition and fertilization, hatching of the newborn, and the presence of young individuals. The stages of Pontogammarus maeoticus were explored in the laboratory. Amphipod samples were collected on the southwestern coast of the Caspian Sea (Jefrood Beach). The animals were transferred to the laboratory along with sediment from their habitat. The samples were maintained under controlled laboratory conditions at a temperature of 25 ± 1°C, a salinity of 9 ± 0.5‰ and in a 12 : 12 h light/dark regime for about six weeks. In this study, we examined the species’ reproductive sequence. The average time spent in the precopula stage was approx. 2.6 ± 0.91 days and embryonic development took about 8.5 ± 1.1 days. Fecundity was estimated as the number of fertilized eggs existing in the brood pouch of each female (average 14.12). The average length of females was recorded as 12.21 mm. The first precopula was observed about 40 days after hatching. The species has a relatively short reproductive cycle and the generations are able to reproduce after a short period (about 40 days). Hence, this species seems to be a good choice for potential use in aquaculture.

Biodiversity and distribution of benthic Meiobenthos in the sediments of the Southern Caspian Sea were studied in order to introduce and determine their relationship with the environmental factors. From 12 stations (ranging in depths from 5, 10, 20 and 50 meters), sediment samples were gathered for four seasons (2012). Temperature, salinity, dissolved Oxygen and pH were measured during sampling with CTD (conductivity, temperature and Depth). Percentage grain size and total organic matter and calcium carbonate were measured. The average water temperature ranged from 9.52 to 23.93 ͦC, dissolved Oxygen from 7.71 to 10.53 mg/L, salinity from 10.57±0.07 to 10.75±0.04 ppt., pH from 7.44±0.29 to 7.41±0.22, EC from 17.97±0.12 to 18.30±0.04 μs/cm2, TDS from 8.92±0.04 to 9.14±0.02 mg/L, total organic matter from 5.83±1.43 to 6.25±0.97% and calcium carbonate fluctuated from 2.36±0.36 to 1.68±0.19%. From the 4 groups of animals (Foraminifera, Crustacea, Worms and Mollusca), 40 species belonging to 29 genera of 25 families were identified Ammonia beccarii caspica, was the common species in all sampling stations. Depth was an important factor in the distribution of meiobenthos. Mean of maximum and minimum Shannon index were measured at depth of 5m and 50 m and were in the order of 0.93 and 0.43, respectively. Account of Shannon and Peilou's index showed that this area is under pressure and is not steady.