Some ecological indices of the Caspian Sea Amphipoda at different depths Guilan offshore

In the present study, some ecological factors were studied for Amphipoda at different depths. The Shannon, Margalef, and Hill indices were used to determine the species diversity, richness and evenness, respectively. In addition, the association and niche overlap values were estimated. Indices of species richness and diversity were highest at 50 and 100m depths, respectively. The ordination of depths shows that the highest dissimilarity was at 20m depth and the lowest dissimilarity at 100 meter. Results of interspecific association and specific overlap of species show that only a few species could have similar ecological requirements. Results show that Paraniphargoides derzhavini with Niphargoides grimmi and Stenogammarus compersus with Amathilina cristata had low associations. Corophium spinulosum with Corophium nobile and Stenogammarus compersus with Paraniphargoides derzhavini, however, had high associations

Metal bioaccumulation in representative organisms from different trophic levels of the Caspian Sea

The bioaccumulations of metals Cu, Cd, Ni, Cr, Co, Mn, Zn and Fe were measured in bivalves, Cerastoderma glaucum, and four species of fishes including Alburnus chalcoides, Liza aurata, Rutilus frisii and Sander lucioperca from various trophic levels of the Caspian food web. The concentrations of Cd, Cr, Co and Ni in most samples of fish were below the detection limits; while the concentrations were detected in most samples of bivalve C. glaucum. The stable nitrogen isotope ratios varied among the samples from C. glaucum (δ^15N=3.5 ‰) to S. lucioperca (δ^15N=13.1‰). Among the four fish species, while the highest concentrations of Mn, Ni and Fe were observed in L. aurata, the lowest concentrations of Mn and Fe were observed in S. lucioperca. These species also had the lowest and highest trophic levels with an average of 3.3 and 4.2, respectively. No accumulation of metals with increase in body size was observed in muscles of species from different trophic levels. The comparison of metal concentrations with the health guidelines for human consumption showed that those intakes were lower than the legislated limits. While there was a strong relationship between trophic levels and body size of A. chalcoides and R. frisii, no significant slopes were observed between the total lengths (TLs) and the Ln concentrations of metals. It is necessary to determine metal concentrations in food resources of fish species, particularly in R. frisii that has significantly different δ^15N in relation to body size

Some biological aspects of Gammarus lacustris Sars, 1863 in Neur Lake Ardabeel province, Iran

A biological study was conducted to find out about reproduction and feeding of G. lacustris in Neur Lake from northwest mountains of Iran. Plankton diversity, hydro-chemical factors and substrate characteristic were recorded monthly. Findings showed that reproduction period of this species was short and limited to May and the mean brood size was 10.2 ± 5.3 eggs per female. The hydro-chemical analysis showed the eutrophic characteristic of Neur Lake in which the average of total organic matter was 3.7 ± 3.0 percent. The phyla representative Bacillariophyta, Chlorophyta and Cyanophyta were observed throughout the study and Chlorophyta was the dominant group. Three zooplankton phyla Rotatoria, Ciliophora and Copepoda were abundant respectively. Study on diet using gut content resulted in identification of 15 plankton genera with some resemblance to planktons of the lake

Investigation on meiofauna and substrate characteristic in the southern Caspian Sea (Guilan Province)

Meiofauna with a size of 100-1000µ having important rule in food webs. This study was carried out in autumn and winter 1992 along 30 transects at depths of 10, 20, 50 and 100m. The sediment samples were collected by grab (0.1 m2 area). In addition to identification of meiofauna, the sediments were examined to determine T.O.M. and grain size parameters. The results showed that bivalvia, foraminifera, nematoda, ostracoda and copepoda were dominant taxa among 12 identified fauna groups, in which foraminifera and bivalvia were the most abundant. The nonparametric Kroscall-walis test showed significant difference among abundance of meiofauna in different depths. The depth of 20m had the most abundance and with increasing depth (5O and 100m), the abundance had a descending trend. The maximum and minimum mean abundance of meiofauna varied from 29315±37248 and 825±498 ind/10 em2 for depth of 10 and 100m, respectively. The substrate characteristics indicated that the depth of 50 and 10m included the most and the least organic matter. Also all depths indicated the same grain size and sediment composition was mostly silt. Most of meiofauna were found in substrates with 4 to 8 % organic matter

Investigation of Mnemiopsis leidyi feeding from the Caspian Sea zooplanktons

Mnemiopsis leidyi was sampled from December 2003 to March 2005 in 11 stations located along four regions Anzali, Khazarabad, Tourkman and Gorgan Bay using METU net in the Iranian coasts of the Caspian Sea. Study of stomach contents of M. leidyi showed that Acartia sp. belonging to Copepoda and Lamellibranchia sp. had the highest frequency comprising 66% and 13% of food items taken by the organism respectively and the least food items taken were Balanus nauplii, Rotatoria, Tintinnopsis and Podon polyphemoides. The maximum mean abundance of food item was Acartia sp. which was shown to be present in stomach content of M. leidyi caught in different depths, seasons and regions in the Iranian coasts of the Caspian Sea. For the M. leidyi larvae, the highest amount of food item was Acartia sp. and Lamellibranchia sp. with an average of 44% and 32% and the maximum abundance of food item for juvenile and mature M. leidyi was also Acartia sp. with an average of 67.5% and 66%. The results showed that the main food item for M. leidyi is Acartia sp. of the Copepoda. Hence, M. leidyi feeding has an important effect in declining zooplankton populations

Evaluation of the effects of isotretinoin for treatment of acne on corneal sensitivity

Purpose: To determine the effect of isotretinoin on corneal sensitivity in acne patients. Methods: Fifty patients (13 men and 37 women) with a mean age of 23.24 ± 3.4 years were selected among patients receiving isotretinoin (1.0 mg/kg) for acne according to inclusion criteria. The Cochet-Bonnet esthesiometer was used to measure corneal sensitivity (in mm filament length) two times (the measurements were done immediately before starting the medication, then 3 months after that), including 3 measurements each time, between 11 a.m. and 1 p.m. by an experienced operator. The average of the 3 measurements in each time was recorded as the final value. One-way analysis of variance and Chi square were used for quantitative and qualitative comparison of corneal sensitivity before and after isotretinoin use, respectively. Results: The mean corneal sensitivity was 5.54 ± 0.05 before medication consumption which decreased to 5.41 ± 0.05 after isotretinoin treatment for 3 months (P < 0.005). After controlling the effect of age and sex, the decrease of corneal sensitivity was markedly significant (P = 0.003) as decreased corneal sensitivity was more pronounced at higher ages and in female gender. In non-parametric evaluation, corneal sensitivity was categorized as substantial (5.5�6 mm), intermediate (4.5�5.5 mm), and low (3.5�4.5). About 72 of the participants had substantial corneal sensitivity before drug consumption, which decreased to 60 after 3 months of treatment. Conclusions: According to the results of this study, corneal sensitivity decreases after three months of treatment with isotretinoin. This decrease is more pronounced at higher ages and in women. © 2018 Iranian Society of Ophthalmolog

Reproduction of the ctenophore, Beroe ovata, in the Caspian Sea water

The experiments with Beroe ovata showed that this ctenophore can survive and reproduce in the Caspian Sea water, though at far lower rate than in the Black Sea; larval growth in the Caspian Sea water was also slower and mortality higher. Maximum fecundity of 2210 and 240 eggs recorded in laboratories of Turkey and Iran, respectively. About 34 to 100% of eggs in the Caspian Sea water could not develop and hatch. Larvae were at different stages of development, usually with size between 1.2 to 2mm. The highest number of eggs and larvae were obtained in tanks where Beroe individuals were together with Mnemiopsis leidyi. The poor reproduction of B. ovata in the Caspian Sea water could be due to both the acclimation stress to low salinity and possible damage of individuals during the transportation

The study and feasibility of Cheshmeh-Ali River and downstream area of Shahid Shah-Charaghy dam in Damghan for aquaculture development

To reveal the fisheries productivity and to get the maximum possible exploitations of the running water resources, existing potentials for aquaculture in Shit and Kordabad rivers in Tarom of Zanjan province were surveyed in a one year round study. In this way 4 and 3 sampling site were respectively selected in Shit and Kordabad rivers and benthic macroinvertebrates and water samples were collected and analyzed at least two times a season and fish fauna were also sampled and studied only two times during the period. All the measured water quality characteristics(such as O_2, water temperature, pH, nutrients, NH_3, BOD_5 and . . . ) were within the normal range suggested for the cold water fish culture. In both rivers no significant differences (p≤95%) were detected for physicochemical parameters within the study sites except for electrical conductivity and total hardness which differed in the firs and last station. Depletion of Agricultural run off and residual from the adjacent farmlands and municipal drainages into the water body of the rivers, were certainly effective in these changes However none of water quality parameters exceed the maximum permitted level for aquaculture. According to the benthic macroinvertebrates study 38 family of 12 taxa and 26 family of the 11 taxa were identified in Shit and Kordabad rivers respectively, most of them belonged to the aquatic insect larvae of the sensitive groups. Community structure indices and Hilsenhof family level biotic index proved a "very good" to "good" water quality criteria for the study sites in both rivers .One fish species in Shit and five species (4 of them were endemic) were identified in Kordabad river. Despite acceptable water quality in Shit river, some inhibiting factors such as adjacent farmlands and dense agricultural land use, high slope of river valley in most region which cause rare suitable lands for locating aquaculture sites, very limited access to road and electricity supply and lack of acceptability to manipulate or divert river water for fish farms, by the local people, are the major constrains for constructing trout farms in Shit river. However constructing a 15 mt capacity rainbow trout farm is possible at first 2 kilometers of the upstream where the water quality and quantity are relatively better and there are some lands with low slope and access to road and electricity supply. Kordabad river has a similar criteria and water quality and quantity at upstream is desirable for rainbow trout culture. The first 2 kilometer of this river is capable of constructing trout farms in some non cultivated lands. Moreover the Kordabad natural dam reservoir is available to conduct its water for further demands. In addition a total of 75mt rainbow trout production in the form of 2 or 3 separate site is possible in this river. Even though the local climate particularly in Kordabad river is acceptable for carp fishes, however land limitations, soil texture and the high volume of water demands, make warm water fishes commercial production impossible

The survey on aquaculture capacity of Ghar-Khatlo dam reservoir in Zanjan province

Qhar-khetlu dam reservoir is in the central part of Ijrud city of Zanjan province with a reservoir volume of 500000 and a water volume of 900000 cubic meters, covering an area of 6 hectares and containing 3500 hectares of the watershed in order to control seasonal floods, drinking water in the village, strengthening the aquifers of the area and As a water supply in the dry seasons, 120 hectares of agricultural land was planted for irrigation.Study of this water source with the aim of measuring biological and non-biological factors, determination of aquaculture production and Fish release capacity and fishing capacity for optimal use of fishery management in Zanjan province was done in 2006.The results of hydrochemical analysis of the water of Qharkhetlu dam reservoir showed that the minimum and maximum temperature of water ranged from 4.5 to 26 ° C, the pH of the water was 4.7 to 8.8, the dissolved oxygen was 7.7 to 12.2 mg, the total water hardness fluctuation was 154 194 mg/L and electrical conductivity of 272 to 390 micrometers per square centimeter, the water transparency was 25 to 380 centimeters.In this study, six phytoplankton classes with 31 genera and 3 classes of zooplankton with 14 genera were obtained. The abundance of phytoplanktons was counted from 150,000 to 206,000 per liter, and the average chlorophyll a, 1.10 micrograms, was estimated. The frequency of zooplanktons were 32 to 132 per liter, as well as the mean of 544 per square meter of macrobenthos.By comparing of the physical, chemical and biological factors and also the results of previous studies of this water source, the conditions for the introduction of warm water and cold water fishes including silver carp, big head carp, rainbow trout out and native fishes including species of Barbus and Capoeta genera are suitable. Estimation of Qhar-khetlu dam reservoir production is 80 kg/ha and its production capacity is 484 kg per year

Marine food web dynamics of small-sized pelagic fish in the Caspian Sea (Iranian’s water)

A mass-balance Ecopath model of coastal areas in the Caspian Sea has been constructed for a quantitative description of the trophic structure of the ecosystem. The model is used to estimate the important biological parameters and relationships among the different ecologically important groups. Twenty five species were used in the present analysis. The model is based on the data collected of Kilka fisheries, beach seining (Bony fish fisheries), and set Gillnet (Sturgeon Fisheries) and also dietary information. Total landings along the Iranian portion of southern Caspian coast reached 39647 t, including sturgeon (41 t), kilka (22873 t) and bony fishes (16733 t) in 2014. Two species of kilka (Common kilka and Anchovy) are important commercially in the Caspian Sea, together accounting in the past decade for > 60 % of the total catch, as well as being a crucial part of the food chain. The mean average trophic level was estimated at 3.17 by Ecopath software. In this research, the mean level were studied between eight species varied from 2.56 to 4.04, Sander lucioperca occupy the highest and the as vimba vimba was the lowest level. The ranges of total mortality varied from 0.5 to 2.56 per years. The food consumption rate was estimated about 101.56 per year Mixd trophic level index (MTI) showed small pelagic fishes as prey, have crucial role in feeding of pelagic predators population such as invasion of the ctenophore Mnemiopsis leidyi, bream fish and benthic fish such as sturgeon. In general, niche overlap was greater in more species such as Alburnus chalcoides, Rutilus rutilus, Clupeonella cultriventris, Rutilus kutum and M. leidyi who consumed large amounts of plankton. In conclusion small pelagic fish exert a major control on the trophic dynamics of the Caspian Sea ecosystems and constitute midtrophic-level populations