A biometrical comparison of Artemia urmiana (Crustacea: Anostraca) cyst between rainy (1994) and drought (2003-2004) years from the Urmia Lake
Alireza Asem1,2*, Ramin Manaffar3 and Nasrullah Rastegar-Pouyani4
1) Protectors of Urmia Lake National Park Society (NGO), Urmia, IRAN
2) West Bio-Processor Inc., Urmia, IRAN
3) Artemia and Aquatic Animals Research Institute, Urmia University, Urmia, IRAN
4) Department of Biology, Faculty of Science, Razi University, 67149 Kermanshah, IRANSummary:
Nowadays, biometrical characterizations of Artemia cyst are used as one of the most important factors in the study of Artemia populations and species particularity; meanwhile these characters can be used as economical index. For example, typically high hatching efficiency is possible due to the small diameter of cysts (high number per gram), therefore small diameter of cysts show someway high quality of cysts. This study was done during a ten years term that also contains two different ecological conditions: rainy and drought. It is important with two different aspects because it covers alteration of A. urmiana during ten years also its variation in best and worst environmental situations in which salinity increased from 173.8 1.1 ppt in 1994 to 280.8 6.7 ppt in 2003/4. In this study the biometrical raw data of Artemia urmiana cysts at seven stations from the Urmia Lake in 1994 and their seven identical locations at 26 studied stations in 2003/4 reanalyzed again and compare together. Biometrical comparison of untreated and decapsulated cysts in each of the seven similar stations between 1994 and 2003/4 show high significant variation (T-test, p<0.000). Based on this study, in whole stations the untreated and decapsulated cyst belong to 1994 are bigger than cysts of 2003/4 without any exception. But there is no logical relationship between salinity and chorion thickness in the Urmia Lake because in one station it increases and in the other one, it decreases and in the next one doesn't show any sensible difference in ten years when salinity had risen 100 ppt. with regard to PCA analyses the stations of two different studied years certainly have been separated with factor 1 from each other. In conclusion, the interaction between genetic and environmental factors can determine and explain variation in the range of cyst diameter in Artemia.
