الفهرس 
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Abstract
The present study focused on one cockle species that dominated at Port- Said coasts. It is Anadara uropigimelana. Various biological aspects were studied in details and the results are summarized as follow: Shell length of Anadara uropigimelana ranged form 10.1 to 90 mm and from 30.1- 90 mm for males and females respectively. The relationships between the shell length and other shell dimensions (shell height, shell width and shell ligament) and weights (total weight, wet weight, flesh dry weight and shell weight)exhibited good correlations. All shell dimensions relationships revealed negative allometric growth (b<1), while the relationships between shell length and weights revealed positive allometric growth (b<3) except for flesh dry weight (b<3). The equations of these relationships are as follow:
Y = 0.8998 X + 0.6585 (for length-height relationships)
Y = 0.8161 X -2.1917 (for length- width relationships)
Y= 0.6801 X- 5.2267 (for length-ligament relationships)
Y= 0.0002 X 3.1165 (for length- total weight relationship)
Y= 0.0001 X 3.1006 (length- shell weight relationship)
Y = 5E- 05 X 3.113 (length- wet weight relationship)
Y = 3E -05 X 2.7977 (length-dry weight relationship).
Low growth rates of shell dimensions and body weights took place during the spawning period of this species. A positive relationship was found between the age of the cockle and the absolute growth in term of shell length and total weight. In case of relative growth, it exhibited a negative relationship. The third and fourth age groups dominated the population of the present study. Von Bertalanffy growth model gives an adequate description of growth during life span of an individual cockle. The obtained growth curves showed a sigmoidal pattern. The observed maximum length (Lmax.) was 86.8 mm. The predicted maximum length (L?) was 98.19 mm. Growth coefficient (K) of Anadara uropigimelana was 0.177. The condition index decreased with age in the cockle Anadara uropigimelana.
Histological description revealed that:
1- Anadara uropigimelana is a diocious species. In addition, ripe ova of A. uropigimelana are surrounded by follicular sacs and attached to other gametogenic stages by fine filaments. After spawning, atresis (oocyte degeneration) appeared in A. uropigimelana.
2- This species is characterized by continuous spawning. A simple synchronization was found between both sexes in the partially spawned phases.
3- The interfollicular connective tissue of Anadara uropigimelana serves as a nutrient reserve utilized during gametogenesis. Spent gonad of this species contained the largest abundance of the interfollicular connective tissue, which was rich in nutritive inclusions and vesicular nutritive cells.
Anadara uropigimelana is characterized by external fertilization as in most bivalves. The different age groups of the species followed the same pattern of gonad development. However, the larger individuals of the species contributed largely to the reproductive activity of the population than the smaller ones. The end of the spawning season of the species was usually marked by oocyte atresia (degeneration and phagocytosis) in female follicles. Concerning sex ratio, males dominated females in the small and large sizes but as a whole, females preponderated males with a sex ratio of 1.4 female: 1 male. Phenomena of sex reversal and hermaphroditism were recorded in this species.