Biometric relationships of the invasive crayfish Procambarus clarkii to the Egyptian freshwater drainage canals | ||
| Egyptian Academic Journal of Biological Sciences, B. Zoology | ||
| Article 6, Volume 7, Issue 1, June 2015, Pages 53-65 PDF (411.7 K) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/eajbsz.2015.13478 | ||
| Authors | ||
| El-Sayed A. A. M.; Al-Damhougy Kh. A.; Zaakouk S. A.; Amer, M. A. | ||
| Faculty of Science, Al-AzharUniversity, Cairo, Egypt | ||
| Abstract | ||
| The specimens of the freshwater crayfish, Procambarus clarkii were collected from the River Nile tributaries at Al-Kanater Al- Khairiya, Qalyoubia governorate during the period from April 2010 to October 2011. The individuals of this species are small lobster-like freshwater crustacean. They have hard- rigid outer exoskeleton, and dark- red, or deep brownish color carapace, characterized by prominent whitish granules during the intermolt stages. The mature individuals of this species are varied from 6 to 10.5 cm in standard length, and from 6.5 to 11.5 cm in total length, and ranged between 10.38 and 56.34 gm in total body weight. The biometric study indicated that the relationship between body weight and standard length for the whole population (males and females) of this species is curvilinear, with positive regression coefficient "b" (slope) equals to 2.998, indicates to an isometric growth and correlation coefficient "r" 0.994, denotes to stability of this species at the prevailing environmental factors. For sex separate, the value of "b" showed also positive isometric regression coefficients, up to 3.359 and 3.118 for males and females respectively, indicating to slightly heavier males than females, without significance difference between sexes (T-test = 1.36, P > 0.05). These results also showed that, the values of regression coefficients "b" for the whole population during different seasons indicated heavier males and females during spring (3.719) and winter (3.879) than those in summer (3.091) and autumn (3.331). The values of relative condition factor "Kn" or the "wellbeing" for this species were varied from 0.89 to 1.11, with an average of 1.01, showing an ideal growth for the whole population with relatively high values in small and medium size-classes less than 9.0 cm in standard length. The relative growth rate of male's right chelae was varied from 2.63 to 6.3 cm, showing highly positive regression with an increase in standard length, sharply declined to vary between 1.93 and 3.93 cm in females, denotes to relatively weak correlation in females. | ||
| Keywords | ||
| Crayfish; Standard length; body weight; relative growth; Condition factor | ||
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