Introduction: Hypersaline ecosystems provide excellent conditions for ecological studies of aquatic ecosystems. Lipar Lagoon is an understudied hypersaline lagoon located in southeasternmost Iran (northern Gulf of Oman). Knowledge about the biotic and abiotic characteristics of this hypersaline water system is limited. This research thus investigated the plankton community composition and abundance, and also its variability under variable environmental conditions over one year. Material and methods: Monthly (five replicates each month) water samplings were performed from 2017 to 2018, during pre-monsoon, monsoon, and post-monsoon seasons. Physicochemical properties of water were measured at the site using a portable multi-meter, while other parameters such as silicate, nitrate, and phosphate were analyzed by spectrophotometry. For plankton identification and density measurements, each sample was fixed by adding 3ml of acidic Lugol’ s solution, and transferred to the laboratory for further analysis. Results and discussion: The plankton community observed during the study period included Fabrea salina, Dunaliella salina, Pseudo-nitzschia sp., and Spirulina sp. Temporal variations in plankton abundance were evident, mostly in September and November, most of which occurred due to the difference in the abundance of D. salina and F. salina. The impact of environmental parameters including salinity and the concentration of dissolved oxygen, nitrite, silicate, and phosphate on the community structure of planktons was significant. Conclusion: The combination of high salinity, high evaporation rate, low freshwater input, and consequently, low nutrient levels may be the main factors behind the low biodiversity in the lagoon. Being under pronounced anthropogenic pressure due to salt extraction activities, it is evident that further hydrobiological monitoring is crucial for the long-term preservation of the lagoon.

Amirkelayeh Protected Area is situated in the north of Lahijan and 28 km to the northwest of Langerud, it covers an area of 1230 hectars. A contribution to the flora, life form and geographical features of the lagoon is given. In this lagoon a total of 85 species and subspecific taxa including 3 charophyta, 5 pteridophyta, 41 dicotyledonae and 36 monocotyledonae were identified. They belong to 45 families and 70 genera. The following families have the highest number of species: Cyperaceae, Poaceae, Ranunculaceae, Lemnaceae and Potamogetonaceae. 53 species (63.1%) are cosmopolitan; it means that they are distributed in the some different regions. The distribution of 22 species is limited to north of Iran. Also, 5 species are mainly distributed in the north and sparsely in the northwest of Iran. Geophyte with 40 species (48.8%) is the most frequent life form of the Protected Area.

Esox lucius Linnaeus1758 is one of the economically valuable species of Caspian Sea. Genetic diversity of marine resources is of vital important in their management and protection. Seven microsatellite loci were used to investigate the genetic variation of 60 samples of Esox in Amir and Anzali wetlands of Gilan. Results showed conspicuous genetic variation in regions using Fst, AMOVA and a relatively high level of gene flow was found among populations. The average observed and expected heterozygosis was 0.626 and 0.662 respectively. Assessment of Hardy-Weinberg equilibrium showed that all samples of studied showed significant deviations from Hardy-Weinberg equilibrium (p£0.05).There were evidences for genetic bottleneck in the populations. Cluster and molecular variance analysis showed two completely distinct population in these wetlands, and this subject must be considered by fishery organization to resource management of this species.

The diet survey of Perca fluviatilis of Arnirkelayeh lagoon was carried out during four seasons of 2001. After collecting the fish samples by different fishing gear such as gillnet, seine, castnet and dipnet, fishes were measured and diet was studied. Also according to this research from 143 specimen, fishes were in the age range of 1+- 6+, total length of 9.5-33.5 cm (T.L= 19.83±4.46 cm) and weight of 10.5 - 350 g (Mean weight of 114.45±77.55g).According to obtained results, the relative lenght gut was 0.58±0.09, index of fullness was 129.5±257.4, fullton's condition factor was 1320.7±534.1 and vacuity index was 7.69%.Perca jluviatilis was fed from 18 kinds of food with respect of frequency were: water bug, Odonata, Gammarus, plant materials, Chironomids, Tinca tinca, Hemiptera, Perca fluviatilis, Snail, Syngnathus abaster, Gambusia holbrooki, Pungitius platygaster, diptera, branchiopoda, trichoptera, tubifex, frog and shrimp.By consideration of composition eaten foods and their frequency percentage in Amirkelayeh lagoon Perca fluviatilis, it can be concluded that this fish is an omnivorous and cannibalism species. Also, feeding habit of Perca fluviatilis changes according to age, season and sex.

We assessed amount of surfactants and their seasonal trend in eight stations in Anzali Lagoon and compared them with allowable levels in the years 2001 - 2002. We obtained 96 water samples and determined their surfactant content using liquid -liquid method applying methylene blue active substance (MBAS).The concentration of surfactants in Pirbazar varied from 0.176 to 0.422 while that of the Sea station was somewhere between 0.098 to 0.049 mg/l. Seasonal concentration of surfactants varied from0.049 to 0.422 mg/l averaging on 0.137 mg/I. A significant difference was found for surfactant concentration in different parts of the lagoon (p<0.05) with the eastern zone being the most polluted area with 0.422 g/l of the pollutants compared to 0.066 mg/l in the Sea. The highest amount of the surfactants was seen in winter in contrast to the lowest amount in spring. No statistically significant difference was found between concentrations of the surfactants in different seasons.

Gomishan lagoon is one of the international wetlands which covers 17700 hectars with 1.5 m in depth. It is located in north eastern of Bandar Turkaman in Golestan Province.It is limited to Atrak river in north, Gorgan river in south and separates from Caspian sea by chain of sandy hills in west. In this study, we had a plan to make flora list of Gomishan. The investigation showed there were 116 species. Halocnemum strobilaceum had grown in east and southeast but Calamogrostis pseudophragmites and Aster tripolium were observed in end of southeast of it. Plant colonies of two last species were proportionate reversely with depth of water. Halophytes plants such as Halocnemun strobilaceum, Salicornia europaea, Salsola rigida, Halostachys caspica, Tamarix ramosissimum and T galica observed in east mostly. The most important halophytes species in east were Halocnemun strobilaceum, Salicornia herbacea Aquatic plants Potamogeton pectinatus, Zannichelia palusteris, Ruppia maritima, Ceratophylum demerosum were in north and northwest, they have grown in shallow deep or have brought near the edge of lagoon by water. Small populations of Phragmites australis, Juncus spp. have been seen in northwest. These results showed that Gomishan lagoon is rich in vegetation and flora of aquatic plants but halophytes plants were remarkable in east and northeast because of salinity.

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 abundanc consist of Copepoda and its naupli (17.2%), Ciliophora (9.6%) and Rhizopoda (6.6%). Other zooplanktons had very few abundance.According to obtained results5 western region of Anzali 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 Polyarthera, Brachionus and Keratella and from Arthropodaphylum, the most abundance genus was found Cyclops and its naupli.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.

Nine Dictyuchus isolates were obtained from floating and decaying twigs and leaves in Anzali lagoon, Anzali County, Guilan province, Iran. They are interestingly distinguished from current Dictyuchus species by the presence of dictyoid and achlyoid type of zoospore discharge, abundant fusiform and spherical gemma, and the absence of any sexual apparatus. In addition, phylogenetic analyses of the internal transcribed spacer (ITS) region of the nuclear rDNA and cytochrome c oxidase subunit I (cox1) gene sequences using Maximum likelihood method indicate its novelty. We preferred not to introduce the isolates as new species due to low number of and sometimes unreliable sequences and lack of type species and suggested to verify Dictyuchus sterilis which has been excluded before. We discussed about taxonomy of the genus in details and provided a revised key to the species. In addition, it was shown that sterility in vitro might be common in this genus.

Amirkelayeh wetland is important and international lagoon of Iran, that is setteled in Gilan province and north of Lahijan. This lagoon is live 15 species, that pike (Esox lucius) is the most abundant among of Lagoon fishes. In 2001, in order to determining of diet of Esox lucius of Lahijan Amirkelayeh lagoon, 156 Picke were catch by Gillnet, Common haul science, Costnet, Dipnet and Electroshock and studied after biometery, age determination and necropsy. Obtained results say that Amirkelayeh Pieke eat a wide range of foods (9 foods). The highest frequency percentage was related to Tench (Tinea tinea) (%24) and Proterorhinus marmoratus (%16) and lowest frequency percentage was related to Syngnathus abaster, Carassius auratus gibelio and Gammarus (each with %4) and Esox lueius, pleochoptera, frog and water beetle each with %8 frequency percentage were in the middle places.This fishes in age groups of 1+- 6+ had average total length of 44.8cm (15.6- 63cm), average weight of 717.9gr (24 - 1700gr), average relative length gut of 0.69 (0.19- 0.97), average of Index fullness of 91/8 (0.7- 422) and average fullton, scondition factor of 723/5 (388/8- 1097/3). According to obtained results, we can say that Esox lueius of this lagoon is carnivores, discovers and cannibalism. Mean while, all of the foods were recognized in the stomach that express the palatability of these foods, and had external selection according to prey size and use of vision and olfactory. Also, diet of Esox lueius was changed in order to season, age and sex.

The diet survey of zibakenar-Kiashar boujagh lagoon Esox Lucius was carried out in four seasons of 1381. Aftar catch of pikes, they were transferred to laboratory and after biometery and age determination, gastro intestinal tract was bring out and ate foods were recognized. In Catched Esox Lucius, average total length was 33cm (minimum 17.7cm and maximum 74cm), average weight was 307.3 gr (minimum 38 gr and maximum 1100 gr), average relative length gut was 0.8 (0.05<0.58), average Index of fullness of 171.6 (0.2-1189.1), average fulltons condition factor of 780.5 (74-7835.2). Obtained results from 122 Esox Lucius express that this fish fed from13 kinds of live foods. In these foods, the highest frequency percentage was related to Odonata (14%), Syngnatus abster (13.8%) and Neogobius kessleri gorlap (13.4%) and lowest frequency percentage was related to Esox lucius and Gambusia holbrooki (each with 4.3%). Esox Lucius were in the age groups of 0-9 (Esox lucius wasnot catch from 7+and 8+age groups). According to statistical studies, there were differences between age, season and sex groups in order to diversity and fed frequency. According to obtained results we can say that bojaqh Esox Lucius is a carnivores, piscivores and even canniblastic.