فهرست مطالب fakhrieh shirood mirzaie

Aquaculture is one of the human activities in which uncontrolled development has negative effects on the environment and biomonitoring can be used to explore it. In this study, the environmental impacts of shrimp farms effluents on macroinvertebrate communities in Gomishan Wetland were investigated. Sampling was performed from six stations monthly for one year and five biological indices were used to investigate the quality status. The results showed that the average density of macroinvertebrate communities was 31934 individual/m2 and the most frequent family was Pyrgulidae. The maximum density among stations was observed in Gorganrood River mouth station. The comparison of density in different months showed that in the first three months of the year, the it was higher than the others; Then, the frequency decreased in summer. Along with the depletion of shrimp farms effluents into the Gomishan Wetland in August, the average abundance of macroinvertebrates increased, but it reduced again in the last four months of the year. The Margalf and Shannon-Weiner indices in different months and stations indicated pollution in this wetland. By calculating the Simpson index, it was found that by increasing the pollution, along with the reduction of water volume, the distribution of macroinvertebrates became more uniform. Pielou index with the mean of 0.4 showed no significant differences between different stations and months. Also, the study of distribution index confirmed the clumped distribution. The water quality in Gomishan Wetland was undesirable, indicating the necessity of effective management policies to improve the water quality in this international wetland.

Various biological characteristics were compared between autumn and spring runs of Caspiomyzon wagneri migrating into the Shirood River, in an attempt to determine whether these were reproductively isolated. Two spawning runs of the same lamprey species in a single river are apparently unique to the Shirood. The autumn sample collected between 21 October and 1 November 2009 comprised 15 adults and the spring sample collected between 22 March and 18 April 2009 comprised 38 adults. While spawning was not witnessed, the significantly shorter mean total length of at least 40 cm in both males and females, and the significantly higher gonadosomatic index in females of the autumn run versus the spring run suggest that the former is closer to spawning than the latter. If one assumes a single spawning population per year in the river, the report by Nazari and Abdoli (2010) of recently spent individuals of Caspian lamprey collected in the Shirood River during April, would therefore imply that the spawning period is remarkably protracted. In order to test this hypothesis, the spawning sites need to be searched for higher upstream over the entire year, particularly in areas where suitable spawning substrate of gravel and sand occurs.