---

Sea cucumber is an important component of the food chain in temperate ecosystems and coral reefs and plays an important role as a poultry eater and has antiviral, anti-cancer and anti-tumor properties in addition to oral administration and in the pharmaceutical industry. It has many uses. This creature swallows sediment on the bottom of aquaculture ponds and is in fact considered as a natural pond for ponds, so it can be grown on shrimp farms individually, thereby accelerating its growth and shrimp and Increasing production per hectare, and ultimately, further boosting the shrimp industry in the region and the province. The study and study of species diversity among marine resources, especially for species that are artificially reproduced or reared, such as sea cucumbers, will be of particular importance in the stabilization of their natural reserves. Color variation in sea cucumber varieties that include green, black and red affects their taste quality and market value, so the need to study and study the biodiversity of these species, especially genetic diversity studies. There are areas where reservoir restoration activities are being undertaken in the field of sea cucumber reserves.

---

Iran is located in a region that is very important in terms of animal geography, but there is little information about its fish fauna, which is very interesting and diverse. In the present research, biodiversity was calculated with Shannon-Wiener, Hill, Pilou and Margalf indices for Kashkan and Seymareh rivers in Poldakhtar city in Lorestan province. Sampling was taken in seven stations and 389 pieces of fish belonging to 15 species of carp, dogfish, catfish and snake fish families were caught and identified. Biodiversity values ​​obtained for Shannon-Wiener, Hill, Pilou and Margalf indices in the downstream of the confluence in the first sampling, respectively were 2.38, 10.64, 0.99, 2.7 And in the second sampling, 2.28, 9.63, 0.95, 2.86, and in the third sampling, 2.4, 10.85, 0.94, and 3.82 were obtained and in the Kashkan river, respectively In the first sampling 1.55, 4.7, 0.79, 1.99 and  in the second sampling 1.2, 3.3, 0.62, 2.5 in the third sampling 1.44 and 4.18 and 0.81, 4.39 were obtained, and in the Symareh river, respectively, in the first sampling, 2.08, 7, 0.85, 2.75, and  in the second sampling, 1.92, 6.8, 92. 0, 2.5 and in the third sampling, 2.02, 7.5, 0.88, 3.6 were obtained that the results obtained from this research showed the greatest biodiversity in the downstream area of ​​the confluence of two rivers, Kashkan and Seymareh.