الفهرس 
chapter 1Only 14 pages are availabe for public view
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Abstract
The brachyuran crabs have long been recognized as one of the most successful lessepsian migrants from the red sea to the Mediterranean Sea via the Suez Canal The present study deals with group of non- commercial crabs inhabiting the Suez Canal The progressive increase in the number of these crabs has been observed to have a negative impact on the fishing gear used by local fishermen and in the marine ecosystem of the canal. A seasonal survey has been carried out during the period between April 2011 and March 2012 in order to describe the present occurrence and distribution of this group along the Suez Canal .Two species were recognized hyastenus hilgendorfi and Halimede tyche as the most abundant species caught by fishermen nets their distribution was discussed with respect to the phenomenon of lessepsian migration.
The population biology of Hhilgendorfi and H Tyche in Timsah Lake was studied based on monthly samples In order to study the masking behavior of the spider crab H hilgendorfi monthly examination of epifauna and epiflora that cover the carapace of this species was carried out. On the other hand an experiment was set up to test possibility of using the galenid crab Htyche as an alternative protein source for fish meal in the diet of Oreochromis niloticus fry as a means to benefit from its unexploited quantities The present study yieled with the following results:
1-A total of eleven species of brachyuran crabs were recognized and identified during the present survey They included eleven genera belonging to nine families The families Portunide and Leucosiidae were represented by two species while the other seven families Pisidae Galenidae Xanthidae Eurplacidae Dorippidae Majidae and Dromiidae each comprised only one species The present study adds two species Dorippe quadridens and Cryptodromia hilgendorfi as first records to the number of brachyuran crab fauna reported on the canal waters
2- Brachyuran crabs of the Suez Canal are mostly Red Sea immigrants The canal can be considered as a link in the process of transportation between the two seas Moreever the Suez Canal can be considered as a habitat itself
3- The biological study revealed that for H hilgendorfi the ratio of females to males was significantly different Males tended to outnumber females throughout the year except for the months between August and October and February and March where the ratio was 1:1 However the ratio of Htyche females to males was insignificantly different There was a predominance of females throughout most of the year except between March and July where the ratio was equal.
4- Depending on the proportions of mature females in each maturity stage the spawning season of H hilgendorfi was found to take place during April to October with a well-defined resting phase between November and March whil the spawning season of Htyche was found to take place between February andOctober with a well-defind resting phase between November and January.