جستجوی مقالات مرتبط با کلیدواژه "geometric morphometric" در نشریات گروه "شیلات"

Macrobenthos are indicators of the physical and chemical changes in aquatic ecosystems. In this research, the diversity of macrobenthoscommunities in the Ortkand River, Iran, was investigated during four consecutive seasons using the Shannon-Weiner, EPT richness indices, and the Hilsenhoff index for water quality at four sampling stations. In addition, sampling of Nemoura cinerea(Arthropoda, Nemouridae) was done to comparemorphological differencesbetween specimens from two upstream and downstream sites using a geometric morphometric approach. The physicochemical parameters of water were also recorded. The entry of fish farm wastewater significantly affects biotic and abiotic environmental factors according to the Shannon-Weiner and Hilsenhoff indices. The results showed a significant positive correlation between DO and Shannon-Wiener index, TDS and the Hilsenhoff index, and DO and EPT richness index. A significant negative correlation was observed between BOD and the Shannon-Wiener index, DO and Hilsenhoff index, and between BOD and EPT richness index. Geometric morphometrics analyses revealed that the two groups differed mainly in pronotum and metanotum morphology. According to the results, monitoring of macrobenthos can help assess rivers’ water quality, and N. cinerea can bea proper bioindicator.

Geometric morphometric method was used to examine the body shape variations among the six populations of Garra rufa, in Iranian part of Tigris basin. A total of 15 landmark-points was used for 170 specimens to hypothesize population differentiation of G. rufa in the six rivers and reservoir. In discriminant function analysis, 85.9% of original grouped cases correctly classified. Principal component analysis (PCA) and canonical variates analysis (CVA) confirmed the significant difference between the populations. The results revealed that the studied populations are divided into three clades based on differences in body depth, caudal peduncle length, backward moving of anal fin. Caudal peduncle showed shortening trend in five populations. Narrower body shape was dominated among specimens of four regions. Studies on body shape provide supporting data on fisheries, stock management, and conservative programs.

The present study was done to investigate the phenotype-environment associations of common carp in the southern coast of the Caspian Sea (Gomishan, Miankaleh, Rezvanshahr, and Anzali Wetland) during winter 2016. The morphometric data of the specimens were procured from their left sides using the Image J and TpsDig2. Both geometric and morphometric methods were applied. The two-block partial least squares was used to examine the relationship between morphological and environmental characteristics. Significant positive correlation (p<0.05) was found between two data sets of morphology and environment, indicating a high level of adaptation for C. carpio in the southern basin of the Caspian Sea. The observed correlation between geometric and environmental data (0.74) was higher than the traditional morphometric-environment correlation (0.50). To the best of our knowledge, this is the first study trying to make a comparison between two methods of morphometric studies in relation to environment, by doing an evenness function on the raw data. The higher level of correlation obtained by geometric data with environmental parameters may imply its advantage in future morph-environment association studies. The obtained results in the present study also can provide basic required information for the wild population conservation strategies in common carp in the southern basin of the Caspian Sea.