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Aims: The aim of the current study was to determine the role of Avicennia marina’s primary production as well as other food sources in the diet of Longjaw thryssa, Thryssa setirostris (Broussonet, 1782) in an arid mangrove ecosystem using carbon stable isotopes of carbon (δ¹³C) and nitrogen (δ¹⁵N).
Material & Methods: We collected five potential food sources in the ecosystem including fresh and senescent leaves of Avicennia marina, particulate organic matter, microphytobenthos and sediment organic matter for further stable isotope analysis. Additionally, fishes were collected with a combination of set nets and seines. The muscle tissue (boneless and skinned, 5 g) was removed from the dorsum of fish.
Findings: Significant differences were found between carbon and nitrogen isotopes of different food sources (p < 0.05). Although, this was not significant for green and senescent leaves (p > 0.05). The average values of carbon and nitrogen isotopic ratios of T. setirostris were 15.93‰ and 13.01‰, respectively. The SIMMR model showed that the contribution of senescent and fresh leaves in the diet of T. setirostris was 15% and 10%, respectively.
Conclusion: The result of the current study emphasized a limited role for mangrove detritus in the diet of transient fishes in an arid mangrove ecosystem.
 

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Potato is one of the most important crops produced in Kurdistan province, western Iran. Although several species of plant-parasitic nematodes have been reported in association with these potato fields, no comprehensive nematode community structure has been investigated. The present study reports the frequency, abundance and prominence value of all nematode groups from 40 potato fields across Ghurveh and Dehgolan regions. Bacterivorous nematodes showed the highest frequency, abundance and predominance in the region, followed by herbivorous (plant-parasitic nematodes), fungivorous and omnivorous nematodes. Predatory nematodes (carnivores) were not recovered probably because field soils were highly disturbed. Root-lesion nematodes were the most predominant among the identified plant-parasitic nematodes. The calculation of the indices of ecosystem function, as well as the plotting colonizer-persister (c-p) triangle, food web faunal analysis and metabolic footprint of the potato fields revealed that most of the studied fields had high proportions of c-p1 and c-p2 nematodes, but nematode individuals of c-p3-5 counted fewer in the population. According to the present study, 50% of the sampled fields represent either stressed and enriched, 30% could be considered as stable and enriched, and 20% may be described as stressed and depleted in terms of their soil nematode food webs. The current study provides the first known study in Iran on nematode assemblages and their implication in soil health.

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We studied the abundance, biomass and diet of Platevindex aff. tigrinus in the Hara Biosphere Reserve in the Persian Gulf. The seasonal sampling (two seasons) was conducted in winter 2018 and summer 2019. Samples were collected from six sites in Qeshm Island and Bandar Khamir. To determine the effect of environmental parameters on distribution of the species, temperature, salinity, pH, sediment grain size, total nitrogen and organic carbon were measured at each site. The results showed that the abundance of P. tigrinus was significantly higher in the winter compare to summer season. However, there was no significant difference in the biomass of the species between seasons. The PCA results showed that salinity, temperature and sediment grain size contributed to the separation of between seasons. The pH and total nitrogen followed the similar pattern in different sites and seasons. Although, temperature, salinity, sediment grain size, and organic carbon showed difference between seasons. The results showed that salinity and temperature were two important parameters in the distribution of the species during both seasons. The species was mainly feeding on the microphytobenthos during winter and on the sediment organic matter during summer.

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The purpose of this research is to investigate the relative importance of Avicennia marina organic matter in the feeding of Ilisha melastoma fish in the Mangrove Biosphere Reserve; It was stable isotope approach. Three primary food sources including mangrove tree leaves, microphytobenthos and suspended organic particles were analyzed isotopically. The samples of primary food sources and fish are converted into pure and simple gases such as CO, CO2 and N2 after minimizing the size and turning into powder. Then the identified isotope ratios are compared with a measured standard and the exact amount of isotope formed in the sample is obtained. In this research, sampling was done seasonally in August in the summer season and February in the winter season of 2019 in the mangrove ecosystems of Bandar Khmer, Hormozgan province.In the summer season, the average stable carbon isotope of primary food sources fluctuated from -28.07 units per thousand for mangrove leaves to -13.58 units per thousand for microphytobenthos.This average in the winter season was obtained from -28.05 units per thousand for mangrove leaves to -13.54 units per thousand for microphytobenthos.The average stable nitrogen isotope of primary food sources in the summer season fluctuated from 1.44 units per thousand for microphytobenthos to 10.72 units per thousand for suspended organic particles.The results of this research showed that in the summer season, suspended organic particles with 63% and in the winter season, microphytobenthos with 45% play the most important role in providing the food needed by the small shemsk fish.