In Dr. Taheri's conversation with ISNA, it was mentioned: the change in the biological structure of the sensitive organisms of the seabed due to the warming of the Caspian Sea

researchers warning; The warming of the Caspian Sea changes the biological structure of sensitive organisms on the seabed

The results of a new research by the researchers of the National Research Institute of Oceanography and colleagues show that the increase in water temperature in the Caspian Sea can cause significant changes in the density, diversity and community structure of Azadzi nematodes. This study, which for the first time investigated the distribution of these small and key organisms on the southern shores of the Caspian Sea, emphasizes that global warming can have profound consequences for the functioning of marine ecosystems by changing biodiversity..

According to ISNA, Dr. Mehrshad Taheri, a member of the scientific staff of the National Research Institute of Oceanography, and his colleagues titled "Spatial distribution and the effects of temperature increase on the coastal nematode community in the South Caspian Sea" in the journal Marine Pollution Bulletin Belongs to the publication Elsevier Ltd It has been published.

In an interview with ISNA, Dr. Taheri said: In this study, for the first time, the distribution of Azadzi nematodes on the southern shores of the Caspian Sea was investigated in 6 stations. The Sisangan station, which had the highest density, diversity and number of species, was chosen for a 50-day experiment in order to investigate the response of the nematode community to the increase in water temperature (20, 24, 27 and 30 degrees Celsius) caused by climate changes in the Caspian Sea..

He noted: The test results showed that with the increase in temperature, the density of the total population and the Shannon diversity index increased significantly (the highest value in the 30 degree treatment). Although the total number of species and community uniformity were not significantly different between treatments, the community structure changed under the influence of temperature..

This researcher of the National Institute of Oceanography and Atmospheric Sciences added: the presence or absence of certain species (such as ‎Daptonema karabugasensis‎، ‎Tripyloides marinus‎ و ‎Adoncholaimus araelensis‎) And the change in their relative frequency was the cause of these changes. Also, the results of these studies showed that the reproduction and nutritional dominance of the nematode community changed with increasing temperature.

According to him, the number of fertile females and immature individuals increased with increasing temperature and the share of predators/omnivores in the society gradually increased. Overall, this study shows that climate change and increasing water temperature can have profound effects on the structure and function of Azadzi nematode community; Therefore, conducting similar studies on other animal groups and investigating the effects of biodiversity changes on the functioning of marine ecosystems is necessary to fully understand the consequences of climate change..

In this article, it is emphasized that global ocean warming refers to the general increase in sea surface temperature and heat content of oceans around the world due to climate change. This phenomenon has also affected the Caspian Sea, the world's largest land-locked body of water, and has brought various environmental consequences such as lowering the sea level..

The warming of the Caspian Sea can have important effects on marine ecosystems, including changes in species distribution, abundance, biodiversity, reproductive cycles and migration patterns of marine organisms. On the other hand, global warming will lead to the reduction of the water level and the shrinking of the Caspian Sea, which can lead to the change of the coastline, the change or loss of the habitat of aquatic and terrestrial species..

The findings show that by the year 2100, the temperature of the Caspian Sea region will increase by about 3.64 degrees Celsius and the rainfall will decrease by about 10% (182 mm). Studies indicate that the increase in water surface temperature in the southern part of the Caspian Sea (about 3.2 degrees in the last 35 years) has been higher than the global average..

An increase in water temperature can have significant effects on the ecology of marine free-living nematodes; A key group of the miofauna community, which are the most abundant metazoans in marine sediments, and their density sometimes reaches millions of individuals per square meter. They play a vital role in nutrient cycling, organic matter mineralization and sediment bioturbation, and serve as energy sources for higher levels of the seabed food chain..

Due to high sensitivity to environmental changes, short life cycle and high species diversity, nematodes are considered effective biological indicators for evaluating human impacts on marine ecosystems..

The animal communities of the Caspian Sea are one of the hot spots (Hotspot) Biodiversity and ecology are known in the world. Despite extensive studies in different parts of the world, the biodiversity of Azadzi nematodes in the southern shores of the Caspian Sea has been less investigated and only a few limited studies have been conducted in the past years..

In this research, first, the spatial distribution of Azadzi nematodes was studied in six stations. Then, using the microcosm test, the effect of three temperature regimes on the characteristics of the nematode community (density, diversity, vertical distribution and community structure) and their functional diversity (maturity index and nutritional diversity index) were investigated.

Taheri emphasized: temperature changes in the range of 20 to 30 degrees Celsius can increase the density and diversity of coastal nematodes and change the structure of the community. This is probably due to the faster growth and reproduction of nematodes and the shorter life cycle of some species. However, the response of the nematode community to increasing temperature is species-specific.

The purpose of studies in the Caspian Sea

This researcher added: In line with the goals of the National Institute of Oceanography in investigating the environmental changes of the Caspian Sea and its current problems including global warming, the purpose of this study was to investigate the effect of increasing water temperature (as one of the consequences of climate change) on the structure and function of the Azadzi nematode community, as important biological indicators, in the southern shores of the Caspian Sea..

He reminded: This goal was pursued in two stages: first, field monitoring and identification of the station with the highest species richness and density (Sisangan station) and then, designing an experimental experiment to measure the response of this community to different temperature levels (control: 20, treatment 1: 24, treatment 2: 27 and treatment 3: 30 degrees Celsius) in a period of 50 days. This research sought to analyze the effects of water warming on important ecological indicators including population density, species diversity, trophic structure and reproductive success of these organisms..

This article was compiled in collaboration with the researcher of the Oceanographic Research Institute, Tarbiat Modares Noor University of Natural Resources and Marine Sciences and the General Department of Environment of Golestan Province, which is as follows.:

Mehrshad Taheri, scientific staff of the National Research Institute of Oceanography and Atmospheric Sciences

Maryam Yazdani Fashtami, academic staff of Tarbiat Modares Noor University of Natural Resources and Marine Sciences

Ahmad Radmanesh (Manbohi), scientific staff of the National Research Institute of Oceanography and Atmospheric Sciences

Seyed Sahab Meera, senior expert of Golestan Province General Environment Department

Journal Marine Pollution Bulletin It is one of the most prominent and influential international journals in the field of marine sciences, due to its high impact factor (usually above 5) and ranking in the category Q1, has a distinguished scientific reputation. The main focus of this journal is to examine all aspects of marine pollution, including chemical pollutants, plastics, heavy metals and their effects on aquatic ecosystems..

The publication of the article in this journal not only shows the quality and originality of the research due to strict judging, but also exposes the research achievements to a large scientific community whose main concern is the protection of the marine environment and its sustainable management..