Study on distribution of the Ctenophore Mnemiopsis leidyi in the Caspian Sea (Iranian Coasts)

In the early 1980s, an alien ctenophore Mnemiopsis leidyi already known as a gelatinous zooplankton was transported (likely via ballast waters) to the Caspian Sea from its introduced or native water of the Black Sea or western Atlantic which caused negative impacts. In this report, distribution of M. leidyi, planktonic and benthic organisms had been investigated in the Southern Caspian Sea (Iranian waters) in 6 transects consisted of Lisar, Anzali, Sefidroud, Nowshar, Babolsar and Amirabad at 26 stations during 2005 and 2006. As a whole, 1422 samples had been analyzed included 258, 346, 217, 117 and 484 belong to ctenophore, phytoplankton, zooplankton, benthos and physicochemical parameters, respectively. M. leidyi abundance and biomass were fluctuated between 284-2751 ind.m^-2 and 16.9- 390/9 g.m^-2 respectively in 2005 while maximum abundance and biomass were recorded in autumn and minimum in winter. In 2006, its mean abundance and biomass were 184-2150 ind.m^-2 and 9.1- 209/8 g.m^-2 respectively. M. leidyi maximum abundance and biomass were noted in summer and its minimum in spring and winter months. Overall, mean M. leidyi abundance and biomass were recorded in 20 m within 1202 ind.m^-2 and 139.5 g.m^-2 respectively. Maximum size of the ctenophore was recorded as 55 and 60 mm in 2005 to 2006 respectively, while less than 10 mm length frequency consisted 83.16 and 82.88 per cent of total population. Spatial_ temporal distribution of M. leidyi in different regions showed it was more abundant in west and east (714- 4494 ind.m^-2) ratio to central parts (13-1519 ind.m^-2) of the Southern Caspian Sea. Species composition of zooplankton had shown the negatively impacts of M. leidyi invasion in the period of sampling as the only 17 holozooplankton were determined with Rotatoria (7 species), Copepoda (4 species), Ciliophora (4 species) and cladocera (1 species). Zooplankton maximum abundance and biomass were recorded in February (3039742901 ind.m^-3 and 372.1575.4 mg.m^-3) respectively and its minimum were in July (12211601 ind.m^-3 and 6.9 7.7 mg.m^-3) respectively which was belonged to Rotatoria (76%) and Copepoda (10%). In this study, 21 species of benthic fauna were deter minted belong to Pseudocumidae (5 species), Gamaridae (4 species) Amphartidae (3 species), Oligochaeta, Balanidae, Xantidae, Nereidae, Scarbicularidae, Carididae, Mytilidae, Herpobdellidae and Chironomidae (each 1 species). Oligocheata was recorded with maximum abundance (943 2502 ind.m-2) and Bivalve consisted of higher biomass (68.7162.5 g.m^-2). From five phyla of phytoplankton, 172 species were determined of Chrysophyta (74 species), Cyanophyta (32 species), Chlorophyta (32 species), Pyrrophyta (24 species) and Euglenophyta (13 species), in which Chrysophyta and Pyrrophyta were noted as main groups with their maximum abundance (up to 65%) and biomass (93%). Maximum water temperature was recorded in August with 29.52.5 ֯C and minimum in February by 9.31.3 ֯C. Mean value of salinity was 12.010.90 ppt, secchi disk ranged between 0.2 to 7 m and oxygen demand varied from 5.95 to 10.54 mg. l^-1). Moreover, silicate concentration was recorded between 200 to 300μg.L^-1, Phosphate measured from 31-47 μg.L^-1, Ammonia varied in 10-29 μg.L^-1, Nitrite (0.6- 1.7 μg.L^-1), Nitrate (0.06-4.20 μg.L^-1, which mainly accumulated in coastal waters of the southern Caspian Sea

An ecological investigating on controlling Mnemiopsis leidyi population activity 6: molecular test in identification of Mnemiopsis leidyi

In this study population genetic structure of Mnemiopsis leidyi were examined by 200 samples from the Caspian Sea. Samples were collected from Guilan province (Astara region), Mazandaran province (Amir Abad region), Golestan province (Gomishan region) and north part of the Caspian Sea. 50 samples were collected from each region. DNA was extracted by phenol - chlorophorm method and its concentration was 50 to 100 nanogram. PCR was performed using 18s rRNA gene. The PCR products of samples were digested by 12 restriction endonuclease enzymes. The digested products accompanied with standard marker (50 bp lader ). In order to measure fragment size samples were run on a 6% vertical polyacrylamide gel. The fragments were visualized by silver staining of the polyacrylamide gel. In this study, Dra I and Alu I enzymes showed different digestion pattern, as each of these enzymes had two genotypes. Other enzymes had similar digestion pattern. RAPD method used by 19 random primers. Ten of nineteen primers showed polymorphism patterns. Statistical analysis of data was performed by Popgene software. In this study, the maximum of genetic variation was in north of the Caspian Sea. Also, the maximum of genetic distance was between north area and Golestan coasts (0.089) and the minimum of genetic distance was between Mazandaran and Guilan coasts (0.001). The UOGMA dendogram showed two clusters. The samples of Mazandaran , Guilan and Golestan coasts placed in one cluster and samples of north area in other cluster The genetic diversity was significantly different between samples of north area and Golestan coasts (p≤0.05). As result, there is a significant genetic divergence between some of samples. Therefore, two genetic group of Mnemiopsis leidyi were identified in the Caspian Sea