Effect of light intensity and photoperiod on growth rate and biomass of Chlorella vulgaris

This study provides information on the effect of three light intensities (37.5, 62.5 and 100L/mol photons.m^- 2 s^-1) and photoperiods (light:dark) cycle 8:16, 12:12 and 16:8h on growth rate, duplication time and biomass production in microalga Chiarella vulgaris. Stock of C. vulgaris was separated from water samples taken at Anzali Wetland, purified and cultured in l000ml Erlenmeyer at constant temperature 25±0.5°C, using Zehnder medium. Cell count was conducted daily and biomass was measured at the exponential growth phase in different treatments. Analysis of variance indicated significant difference (P<0.05) among light regimes. The maximum growth rate 1.13d^-1 was observed at 100L/mol photons.m^- 2 s^-1 and 16:8h light duration and also the minimum duplication time 0.61d^- 1 occurred at this treatment. The maximum biomass 2.05gr^-1 was recorded at 62.5L/mol photons.m^ -2 s^-1 and 8:16h light period

Spatial variation of symbiotic dinoflagellates on coral reefs of the northern Persian Gulf

Density, mitotic index, Chlorophyll-a content and cell size of symbiotic dinoflagellates of dominant reef-building corals were measured at two different depths in Kish Island and from one depth of Larak Island in the Persian Gulf. The higher densities of symbionts were found in shallow waters of Kish Island. However, ANOVA analyses of the mitotic index yielded mixed results. The cell sizes of symbionts did not significantly differ among depths, except for Porites corals at one site in Kish Island which displayed the larger cells in deeper water. The comparison of symbiont attributes between islands exhibited intraspecific variability. Density of zooxanthellae was only different in Porites and Favia corals between islands. Chlorophyll-a density (cm-2) was significantly different between islands in all species, with higher values for Kish corals. Chlorophyll a cell-1 was only significantly different in Porites and Platygyra corals, with higher values for Larak Island. The symbiont cell sizes usually exhibited no variability, except for Porites corals with larger sizes in Kish Island

Identification of a hermit crab, Clibanarius signatus, in Hormuz Island: abundance, sex ratio and shell selection behaviors

In order to establish a complete list of the hermit crab species in the southern coast of Iran and also determine some of their biological characteristics in the intertidal zones of Hormuz Island, a seasonal sampling collection was conducted in 6 intertidal stations during the years 2010–2011. The 542 collected samples were found to be Clibanarius signatus, which identified in the island. Comparing the samples with the metatypical hermit crab samples in the Zoological Museum, University of Tehran, verified the species. The one ways ANOVA with LSD test showed a significant difference (p < 0.05) in the abundance of the species in some stations, but seasonal changes did not significantly affect the abundance. Male-female sex ratio was 1/52 male: 1 female. Seasonal study of sexes (male, non-ovigerous female, ovigerous female) confirmed that species did not have a particular spawning season, nevertheless the spawning increased in summer. The shell selection behaviors showed that the hermit crab uses the shells of 36 gastropod species (24 genera) for protecting its abdominal section

Ecological classification of southern intertidal zones of Qeshm Island, based on CMECS model

The “Coastal and Marine Ecological Classification Standard (CMECS)”, a new approach to ecological classification, was applied to 122 km of the southern intertidal zone of Qeshm Island located the Hormouz Strait - the Persian Gulf. Two components of this model, Surface Geology (SGC) and Biotic Cover (BCC) were used. Considering the extent and geomorphological alternations of the covered area, 12 sampling sites within 5 sub-regions were designated using by GPS. In total, 60 habitats (biotopes) with 47 codes were determined; this variety of biotopes is directly related to the diverse surface geology (substrate) of the covered area. Most of the biotopes and codes were recorded in the mid-eastern coastal zone, due to heterogeneity in substrate structure associated with numerous ecological niches in rocky shores. Crustacean species such as Eriphia smithi, Thalamita prymna, Molluscan species such as Clypeomorous bifisciatus, Cerithium caeruleum and echinoderm species such as Echinometra mathaei and Ophiactis sp. were characteristic of rocky shores, while Crustacea groups including Ocypode rotundata and Dotilla sp., and Umbonium vestiarium (Mollusca) were characteristic of sandy shores. Although the highest number of codes was recorded in Zeitun Park site (Eastern coast), it did not possess the expected specific species (such as Diadema setosum, Linckia multiflora and Ophiocoma scolopendrina), that were encountered in sites with similar surface geology. This could have been caused by tourist traffic at the Zeitun Park site

Effects of supplemental dietary L-carnitine on growth and body composition of beluga (Huso huso) juveniles

The effect of feed supplemented with L-carnitine at four levels of 0, 300, 600 and 900mg kg-1 on growth performance and body composition of beluga, H. huso, juveniles were evaluated in two separate trials. In the first trial, 180 juveniles (525±9gw) were fed with the test diet for a period of 71 days, and the trial extended to another 126 days in the second phase by randomly selecting 120 juveniles (870.7±32g) and rearing them with similar diets. All trials, in triplicates, were conducted in circular fiberglass tanks (200cm diameter, 40cm height).The fish were fed 4 times daily to apparent satiation. In the first phase, L-carnitine did not significantly affect mean final weight, feed conversion ratio (FCR) or specific growth rate (SGR) of the fish, however, the fish receiving 900mg kg-1 L-carnation showed better growth increment, SGR and feed efficiency (FE) than those in control group (p³0.05); neither did it significantly affect protein, lipid, moisture or ash as well as leptosomatic index (HSI) (p³0.05). The protein efficiency ratio (PER) was significantly affected by L-carnitine supplemented diet, particularly at 900mg kg-1(p£0.05). In the second phase, fish fed L-carnitine-supplemented diets produced significantly higher W2, SGR and PER than the control group (p£0.05), but HSI decreased significantly (P£0.05). At the end of the trial, the whole body composition of fish did not differ significantly among experimental treatments, but slightly reduced lipid content was observed at 600 and 900mg kg-1 L-carnitine (p£0.05).The results of this study indicated that supplementation of diets with 300-600mg carnitine kg-1 improved growth rate, feed utilization and stimulated protein-sparing effect in this species

Impact of two parasitic trematodes, Meiogymnophallus minutus and Himasthla spp., on the growth of the cockle, Cerastoderma edule

The impact of two principal parasitic digenetic trematodes, Meiogymnophallus minutus and Himasthla spp., on the growth (weight and length) of the cockle, Cerastoderma edule, in Arcachon Bay (France) was studied. The experiment was conducted in the land-based mesocosms. The velocity of infestation with both trematodes was far more rapid during summer in the cockles already parasitized with these trematodes (0.35 to 0.45 metacercariae day-1) than those of healthy ones (approximately 0.01 metacercariae day-1). The parasitism had also an effect on the growth rates of cockles. During 190 days of the experiment, the daily growth speed varied from 0.001mm.da/ to 0.021mm.day-1. On average, the growth was slightly more important in healthy cockles after the start of experiments (0.014mm.day-1) than those initially infested cockles (0.011 mm.day-1). The experiment also showed that infestation of hosts with trematodes could perhaps disturb their immunity system, as the intensification with trematode parasites had been favored by already infested cockles

Seasonal distribution of dominant phytoplankton in the southern Caspian Sea (Mazandaran coast) and its relationship with environmental factors

Seasonal distribution of phytoplankton and factors affecting their presence in the Mazandaran coastal ecosystems were investigated in 2012. In this study, Distribution of the phylum and dominant species of phytoplankton and water quality parameters were evaluated along 4 transects (Amirabad, Babolsar, Noshahr and Ramsar) in the different layers of the water column at final depths of 5, 10, 20 and 50m. Variation of the dominant species and environmental parameters was analyzed using Principal Components Analysis (PCA). Average annual phytoplankton density was 318687823 cubic meters, the highest density in winter and lowest in spring was determined. Totally, 5 groups and 129 species of phytoplankton were identified, including Bacillariophyta (58 species), Cyanophyta (24), Dinoflagellata (22), Chlorophyta (17) and Euglenophyta (8). The dominant species in the water body were Exuviaella cordata of the Dinoflagellata (61.25% of the species) in spring, Oscillatoria sp. of the Cyanophyta in summer and autumn (48.69 and 71.91%, respectively) and Pseudo-nitzschia seriata of the Bacillariophyta (66.12%) in winter. This study showed that thermocline, riverine transport, Mnemiopsis leidyi and opportunistic phytoplanktonic species with high competitive ability (Cyanophyta and Dinoflagellata (were the most effective factors on spatio-temporal variations of phytoplankton. Temperature, silica and inorganic nitrogen play an important role in population dynamics are diatoms, while temperature, inorganic and organic phosphorus and inorganic nitrogen for Cyanophyta and Dinoflagellata are important

Ecological classification of intertidal biotopes in north Qeshm Island based on coastal-marine standard (CMECS)

The “Coastal and Marine Ecological Classification Standard” is one of the new and complete approaches to understand of marine habitats. We were applied Biotic Cover and Surface Geology as the two components of the classification to the northern intertidal stretch of Qeshm Island. Considering the extent and geomorphology of the area, 9 sites were designated. Density and temporal distribution of biotic community were determined using 0.5×0.5 m quadrate, and sediment was sampled up to 15 cm below the surface to determine its type and material. Totally 32 codes were determined for 40 habitats (biotopes), and their positions were displayed on map. Our result show that the biotope diversity decreases westward. Also, the highest and lowest numbers of species were observed in sandy and muddy-sand substrates, respectively. It seems that habitats distribution is mainly determined by the substrate type, but other factors can also affect this distribution

Effects of different by catch reduction devices (BRDs) in shrimp trawlers in the Persian Gulf

The effect of different bycatch reduction devices in decreasing bycatch of commercial fish species with the length of less than LM50 (the length from which, 50% of them are matured) in shrimp trawlers were examined. The experiments were conducted in Persian Gulf (Bushehr and Hormuzgan provinces) during the shrimp season, years 2000-2001. In this study four types of bycatch reduction devices (Grid, Nafted, Fish eye and Square mesh window) were used. Double rig trawl was used, one of them as an experimental trawl and the other as the control. Different treatments like one device or two devices were installed on experimental shrimp net. After hauling the trawl, frquency of different commercial species with length less than LM50 was determined in both nets, and the results were tested with Paired Willcoxon test. The results have shown that although all the devices have a reductional effect on bycatch of the young and juveniles of commercial species, but the amount of reduction with setting Nafted and Grid, either single or combined with another BRD was significantly higher than the control one (P ≤ 0/05). The amount of by catch reduction devices with different treatment (different devices either single or paired) according to the season of the experiment were also tested with Kruskal- Wallis test, which shows significant differences (P≤0.05) between the frquency of young and juvenile individuals of some species during different experimental seasons. According to this study, by using Nafted and Grid devices in the trawl nets of all shrimp vessels during its season, about 400 to 500 thousand of juveniles and young individuals can escape from the nets

Distribution, abundance and biomass of Ampelisca sp. in the Iranian continental shelf of the Oman Sea

This study was conducted to determine distribution, abundance and biomass of Ampelisca sp. in the Iranian continental shelf of the Oman Sea from Jask to Gwadar (approximately 350 km stretch). Sampling was carried out in 10, 50,100 and 200m depth along five transects of approximately equal distances from each other. Sampling was done with Van Veen grab (0.1 m^2) in three replicates; temperature, salinity, and Dissolve oxygen were recorded by CTD, sediment sample was collected for analysis of physical parameters for sediment at each station. The PCA and correlation of Ampelisca sp. abundance and biomass with all the environmental parameters were determined. The maximum abundance and biomass of Ampelisca sp. was recorded at 10m depth, which decreased as depth increased. It was observed significant correlation among abundance and biomass with dissolved oxygen, sand percentage and temperature