Stomach contents of Mnemiopsis leidyi in the Iranian coastal waters of the Caspian Sea

This study was carried out from August to November 2002 in the Iranian coastal waters of the Caspian Sea (Guilan province). The results showed that gut contents of Mnemiopsis leidyi included a wide variety of prey including 84% of zooplanktons and 16% of phytoplanktons. The most abundance of intaked foods was Acartia (belongs to Copepoda) with 34% frequency and the least was podon (belongs to Cladocera) with 0.74% frequency. Also 3.0% of fish eggs and 4.2% of molluscs were found among stomach contents. Maximum and minimum fed phytoplanktons were Chrysophyta (67.0%) and Pyrrophyta (3.7%), respectively. The young specimen consumed more zooplanktons and phytoplanktons comparing to adult ones. According to laboratory observations, this ctenophore cannot digest phytoplanktons

The density and distribution of plankton in Hevigh River, Guilan Province

A Comprehensive hydrobiological and hydrological investigation was conducted on Hevigh River, west of Guilan Province from 2001 to 2002. Totally, 4 Phyla of phytoplanktons including 21 genera were observed. The maximum phytoplankton density belonged to the Phylum Chrysophyta with genera, Nitzchia, Diatoma, Cocconeis, Navicula and Cymbella comprising 95.7% of the phytoplankton population throughout the year. Chlorophyta ranked second with genera Scenedesmus, Cruciginia and Anicistrodesmus, comprising 2.20% of the population during the year. Cyanophyta with Oscillatoria and Euglenophyta with Euglena consisted the remaining few percents of the phytoplankton population. Zooplankton population in Hevigh River was found to be very poor, and mostly belonged to Protozoa and Rotatoria. However, 4 Phyla and 12 genera of zooplanktons were distinguished in the River the highest density of which belonged to Protozoa with genera Amelia, Difflugia, Cyphoderia and Euglypha, comprising 64% of the total population. Rotatoria with genera Keratella, Cephalodella, Lecane and Rotaria, consisted 14% of the zooplankton population during the year. Arthropoda, Nematoda, Tardigrada were very low in numbers

Ecological study of zooplankton communities in the Persian Gulf Martyrs Lake (Chitgar-Tehran) and the first report of the freshwater jellyfish Craspedacusta sp. (Cnidaria, Limnomedusae) in Iran

This study focused on zooplankton structure, biodiversity, relationship between a biotic parameters and zooplankton variation, and trophy state of the Persian Gulf Martyrs Lake (Chitgar-Tehran). Based on the lake condition, samples were collected by Juday net at the 5 stations between 2013 and 2014. This study identified 36 zooplankton taxa comprised of Arthropoda (6 genus), Protozoa (6 genus), Rotatoria (20 genus), Nematoda (1 genus), Gastrotricha (2 genus) and Oligochaeta (1 genus). Furthermore, the first record of the freshwater jellyfish Craspedacusta sp. in Iran, with size group of 15-20 mm in diameter in September is reported in the Chitgar lake. The Rotatoria abundance average was measured 61 ±18 ind.l-1 in the lake. The Nematoda, Gastrotricha and Oligochaeta taxa were measured the lowest abundance (< 1 ind.l-1 ) in this study. The annual average zooplankton abundance was measured as 72±18 ind.l-1 . The PCA displayed, the Rotatoria Trichocerca sp. and Polyarthera sp. were dominated with high components loading, low variance and high abundance. The CCA showed, there was no correlation between Rotatoria abundance and a biotic parameters. Based on the zooplankton structure and bio-indicator, the lake situation is in the meso-oligotrophic category. Thus, it is might be increased eutrophication trend due to no management and no aquatic control in this ecosystem

Abundance and distribution pattern of plankton in Anzali Lagoon

A comprehensive hydrobiological and hydrological investigation conducted in Anzali lagoon from 1997 to 2000. During this study, a total of 5 phylum and 62 genera of phytoplanktons and 10 phylum and 50 genera of zooplankton were identified. The results showed that for phytoplanktons the abundance of Cyanophyta, Chrysophyta, Chlorophyta, Euglenophyta and Pyrrophyta were calculated 61.8%, 29.1%, 8.2% 0.7% and 0.2%, respectively. The most abundance of zooplankton belongs to Rotatoria (60.8%), after that other group of zooplankton had more abundance consist of Copepoda and its nauplii (17.2%), Ciliophora (9.6%) and Rhizopoda (6.6%). Other zooplanktons had very few abundance. According to obtained results, western region of lagoon (Abkenar) is a rich region of planktons in which the most dominant phylum of phytoplanktons was from Cyanophyta with genera of Oscillatoria, Anabaenopsis, Microcystis. The most abundance of zooplanktons were genera of Polyarthra, Brachionus and Keratella and from Arthropoda phylum, the most abundance genus was found Cyclops and its nauplii. The Planktonic study indicated that Anzali lagoon is one of the richest lagoon in Iran with high production and potential water for feeding of fishes and their larva

The density and distribution of the plankton, in Maco Reservoir Dam

A comprehensive hydrobiological and hydrological investigation conducted in Maco Reservoir dam during 1997-1998.The result showed that the maximum density of Phytoplankton belongs to the Phylum of Chrysophyta with species of Cyclotella menenghiniana, Synedra ulna and Diatoma vulgare. This Phylum observed mostly in summer and showed the most; frequency (%76) population during year. After Chrysophyta there was Chlorophyta phylum with species Scenedesmus bijuga and S. bijugatus with %19 frequency during year. Also, there were other phytoplankton phyla, namely: Cyanophyta with Oscillatoria limosa, Euglenophyta with Euglena sp. and Pyrrophyta with Ceratium hirdinella that had a few percent of population in the year. The highest density of Zooplankton belongs to the phylum of Rotatoria with species of Synchaeta oblonga, Polyarthera vulgaris and P. dolichoptera. This Phylum was observed mostly during autumn and had %74 frequency during year. The second phylum belongs to Arthropoda, that was included two orders consist of: Copepoda (%16 population) with speices of Cyclops vicinus and C.viridis and their naupli, order Cladocera (%7 population) with speice of Daphnia longespina. They were recognized as the most important zooplankton in Maco reservoir dam. The planktonic studies and observations show that there is a well enough potential of food for feeding of fishes inhabited in this dam

Studying Caspian shad (Alosa caspia caspia) diet in southwest coastal area of the Caspian Sea, Guilan Province waters

Little is known about the biological characteristics of the Caspian shad, a commercial fish of Clupeidae family living in the Caspian Sea. Monthly random samples of the fish were collected at the Guilan province shores, southwest of the Caspian Sea from October 2001 to August 2003. Beach seine and gill nets were used in the sampling. Food items, condition factor and feeding changes with the change in the fish age, sex, station and season after invasion of زtenophore Mnemiopsis leidyi to the Caspian Sea were studied. Samples (n=262) had fork length 88-235 (156.7±31.9) mm, weighed 8-196 (51.92±32.7) grams and aged 1-6 (2.81±0.9) years old. The Vacuity Index (CV), Intestinal Relative Length (RLG) and Index of Fullness (IF) of the specimens were determined as 10.3%, 0.52±0.03 and 102.9±114.5, respectively. Phytoplankton (specially Rhizosolenia and Spirogyra) comprised 1.8%, zooplanktons (Ostracoda, Rhizopoda, Cladocera, Rotatoria, Copepoda, Cirripedia, Mysidacea, Bivalvia larvae and bony fishes larvae and eggs) comprised 98.0% and benthic fauna (Framinifera, Porifera, Cumacea, Amphipoda, insects larvae and Palaemonidae) comprised 0.2% of the food abundance in the fish stomach and intestine. Among the food items, orders Copepoda (Acartia spp.) and Cirripedia (Cypris balanus) were the main food, comprising 83.1 and 12.9% of abundance, respectively. Acartia comprised 97.3, 80.4, 48.0 and 68.3% of the food in autumn, winter, spring and summer, respectively. For Cypris balanus, these figures were 2.0, 2.6, 41.9 and 25.3% for the seasons. No significant difference was found in food diversity and its abundance between male and female fish and between different ages. Generally, Acartia spp. and Balanus were dominant food items in the male and female fish and in different sized specimens. Acartia comprised about 97.0% of the food abundance in Talesh and Kiashahr areas and 65.7% in Anzali shores. The zooplankton, as the main food item of the fish have suffered a major decrease due to the invasion of Mnemiopsis leidyi to the southern Caspian Sea. Hence, the index of fullness (IF) and growth of the fish shows a great reduction recently

State of Mnemiopsis leidyi (Ctenophora: Lobata) and mesozooplankton in Iranian waters of the Caspian Sea during 2008 in comparison with previous surveys

Mnemiopsis leidyi which was accidentally introduced into the Caspian Sea in 1999 and since then has colonized extensively. The horizontal distribution of M. leidyi and dominant mesozooplankton species was investigated in the south western Caspian Sea during February, May, July and November 2008. The average number and biomass of M. leidyi were in the same range (ca 200 individuals m^-3 (2000 ind m^-2)) and 16 g wet weight m^-3 (180 g m^-2) in comparison with previous surveys. As in previous years the population consisted mainly of individuals <1 cm. The decline in mesozooplankton species observed since 1996 continued in 2008. Only two species of the previously recorded 24 Cladocera species were found in 2008. Of five Copepoda species recorded in 1996, only one, Acartia tonsa, was found in 2008 and even here adult individuals have reduced 3-fold since 1996. Bivalve larvae have declined by one order of magnitude since 1996. Among the dominant species, only the numbers of Cirripedia larvae and in part the numbers of Pleopis polyphemoides (Cladocera) were in the same range as in 1996

The study of zooplankton population structure in Anzali Wetland

Anzali wetland is one of the most important places for migratory fishes. Zooplankton organisms are the first consumers in the ecosystem. They are perfect food for the larvae of fishes. Six stations from different areas of wetland were examined for the study of zooplankton population during March 2011 to April 2012. Sampling was done by tube (PVC) and passing through of 30 micron plankton net. The samples were identified and counted by inverted microscope. According to the results, 60 Genus and 6 phylum (11, 31, 10, 2, 1, 1, 1, 2 genus of phylum Protozoa, Rotatoria, Arthropoda, Gastrotricha, Mollusca, Tardigrada, Nematoda, Porifera, Annelida) respectively were identified. The results showed that the maximum annual average density of zooplankton was observed with 2497 ± 687number per litre in Karkan station and the population was more in the summer than in other seasons. Density of Rotatoria, protozoa and superclass Copepoda were 48%, 45% and 6% respectively. Results showed the population structure of zooplankton did not change much compared to past studies (due to improper environmental conditions), excluding Protozoa but the diversity of all zooplankton group is extremely declined. Kruskal Wallis test showed there was not significant difference between density of zooplankton in different stations, months and seasons (p>0.05), but significant differences were found between densities of different zooplankton phylum (p<0.05)

Phytoplankton species in Anzali Lagoon and Caspian Sea coastal waters

Plankton samples were collected in 28 stations in Anzali Lagoon and nearby coastal areas during 1997-1999. Overall, 9 phyla, 134 genera and 278 phytoplankton species were identified. Of the identified species, 56 genera and 107 species belonged to phylum Chlorophyta, 39 genera and 87 species belonged to Bacillariophyta, 2 genera and 2 species were from Xanthophyta, 4 genera and 4 species belonged to Chrysophyta, 6 genera and 34 species were from Euglenophyta, 7 genera and 9 species belonged to Pyrrophyta, I genus and 2 species were from Cyanophyta, 18 genera and 32 species were from Cyanophyta and I genus and species was of Rhodophyta. We showed Cyanophyta and Bacillariophyta to be the most abundant phyla and western and southern parts of the lagoon the richest in terms of phytoplankton diversity and density. Cyanophyta planktons were the most abundant in summer in western part of the lagoon and were comprised of Microcystis aeruginosa, Oscillatoria limosa and Anabaenopsis raciborskii. Diatoms were observed throughout the year everywhere in the lagoon with their diversity being highest in late autumn, winter and spring. The dominant species of Bacillariophyta were Cyclotella meneghiniana, Synedra ulna and Nitzschia acicularis in the lagoon while Rhizosolenia calcar was dominant in estuarine and coastal areas during summer. Of Chlorophyta, species belonging to Scenedesmus were abundant in spring and of Euglenophyta, Euglena acus and Trachelomonas armata were most abundant in southern part of the lagoon in spring and summer. Gymnodinium coronatum from Pyrrophyta was abundant in summer in western part of the lagoon while Exuviaella cordata was dominant in estuary and coastal areas during autumn

Distribution of zooplankton in the southern Caspian Sea

The zooplanktons were studied in spring, autumn and winter in the southern Caspian Sea in 1996. Sampling carried out in four season. In each season, 180 specimens were identified and their frequency calculated per m^3. 55 species of zooplanktons were identified including 55% Cladocera, 15% Copepoda and 11 % Rotatoria, 9% other groups such as meroplanktons. The maximum species diversity was observed for Cladocera and the maximum frequency were observed for Copepoda. The Copepoda affected on abundance of zooplanktons as this frequency included in spring, summer, autumn and winter that were 38% to 97%, 22% to 92%, 71 % to 99% and 31 % to 92%, respectively. In summer, the Copepoda and lamellibranchiata larvae had main role in formation of zooplankton population in western region of the southern Caspian Sea, but in autumn, 70% of zooplankton population were copepods. The frequency of zooplanktons in spring, summer, autumn and winter were calculated 4081 to 20143; 7812 to 65741; 10850 to 34406 and 4510 to 20576 inch/m^3, respectively. The maximum biomass was observed during summer with 200 mg/m^3