Morphometric Features of the Shell Population of Brachidontes pharaonis (Fischer, 1876) (Bivalvia: Mytilidae) from Alexandria Coast of Egypt

ABSTRACT

Background and Objective: Morphometric analysis of marine mussels based on shell dimensions have been reported by many researchers for Mytilidae but few published studies about morphometric of Brachidontes species. The main objective of the present study is to detect the size frequency distribution, allometry and condition index of the Lessepsian mussel species B. pharaonis along Alexandria Coast, Egypt. Materials and Methods: In the present study, three sites were selected along the coast of Alexandria City (Miami, Stanly, Al-Anfoushy). Regression analysis was applied between different morphometric parameters such as shell length and height/width/total weight/meat weight relationships. Results: The data revealed that the shell size ranged from 0.5->36 mm in all seasons and the most abundant shell size group was (4-8 mm), which represented by high percentages during spring, autumn and winter (32.5, 27.8 and 26.5%, respectively), while the large sized individuals represented by small percentages. The monthly b values of length/height, length/width and length/total weight varied from 0.3945 in November to 0.4202 in February, from 0.3507 in March to 0.4377 in May and from 2.8257 in June to 3.0607 in August, respectively. The results showed that there are two peaks for the mean of condition index during spring, summer and autumn. Conclusion: The shell growth of B. pharaonis proves a short life cycle with spawning all year round and the abundance of small shells with high density of the population in the studied area. Regression analysis showed strong correlation between length height/width and length-weights.