International Research Journal of Natural Sciences (IRJNS)

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Pachygrapsus marmoratus

Morphology and age cohorts of Pachygrapsus marmoratus (Grapsidae) in the southern Mediterranean Sea (Published)

The aim of this work was to establish morphological traits of P. marmoratus inhabiting the rocky intertidal zone of the southern Mediterranean Sea coast. 457 P. marmoratus collected randomly from the AL-Haniyah, Al-Hamamah, and Susah sites, eastern Libya, during 2019 were used in the study. The largest carapace length (CL) and weight (WW) were 35.1cm and 31.0g, respectively, while the minimums were 8.50cm and 0.40g. The means were 24.5cm and 10.2g. The order of WW by season was: winter and spring > fall > summer; by site: Al-Haniyah > Susah > Al-Hamamah; males being heavier than females. The WW-CL relationship was WW=0.001*CL**2.817; R2=0.909. The condition factor of P. marmoratus was highest in spring and lowest in summer, highest in Al-Haniyah and Susah and lowest in Al-Hamamah, and similar for both sexes, it increased in a negative allometric manner as the crab grew. The morphometrical parameters of male P. marmoratus were higher than those of females. Most morphometrical parameters scored higher values in winter and spring, followed by fall, and summer, with Al-Haniyah and Susah parameters being higher than the Al-Hamamah ones. Temporal and spatial variations of the morphometric parameters were discussed in terms of the availability of food and prevailing environmental conditions. Regressions of females and males P. marmoratus morphometric parameters with CL were strong and positive. Bilateral dimorphism was not observed. Four-year age groups, +1 (11-12mm), +2 (16-18mm), +3 (25-26mm) and +4 (32-33mm), comprised the P. marmoratus population.     

Citation: Ayiman Faraj Eisay, Hind Abdrabba Yousef, Sayed Mohamed Ali, Ramadan A. S. Ali (2022) Morphology and age cohorts of Pachygrapsus marmoratus (Grapsidae) in the southern Mediterranean Sea, International Research Journal of Natural Sciences, Vol.10, No.3, pp.14-32

Keywords: Libya., Mediterranean, Morphology, Pachygrapsus marmoratus, morphometry

Food and feeding habits of Pachygrapsus marmoratus (Grapsidae) crab in the southern Mediterranean Sea (Eastern Libya) (Published)

The present study aimed to establish spatiotemporal food and feeding habits of the crab Pachygrapsus marmoratus inhabiting the rocky shores of the southern Mediterranean Sea coast, exemplified by Al-Haniyah, Al-Hamamah, and Susah sites in eastern Libya, and relate them to crab morphometric traits, and abundance of food organisms in the habitat. A total of 425 crabs collected during 2019 were used in the study. The minimum and maxim carapace length (CL), and total weight (TW) were: 8.5-35.1mm, and 0.4-31.0g in order, the means were 26.79mm and 12.37g. P. marmoratus is an omnivore facultative feeder, i.e. feeds on what is available in its habitat. Stomach fullness was established and discussed in terms of season, site, crab sex and growth, and availability of food in the habitat. The abundance of food in the stomach by taxa vary according to the site, and crab sex and size, but the overall trend was cnidaria and algae > crustacea > mollusca > seaweed, by season it was fall > spring > winter > summer. Cnidaria and mollusca were more abundant in stomachs of P. marmoratus of Al-Haniyah, Crustacea in Al-Hamamah, and mollusca and crustacea in Susah crab’s stomachs.

Citation: Hind Abdrabba Yousef; Ayiman Faraj Eisay; Ramadan A. S. Ali; Sayed Mohamed Ali (2022) Food and feeding habits of Pachygrapsus marmoratus (Grapsidae) crab in the southern Mediterranean Sea (Eastern Libya), International Research Journal of Natural Sciences, Vol.10, No.3, pp.1-13

Keywords: Feeding Habits, Food, Pachygrapsus marmoratus, eastern Libya, southern Mediterranean Sea

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