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

Eisay, Ayiman Faraj and Yousef, Hind Abdrabba and Ali, Sayed Mohamed and Ali, Ramadan A. S. (2022) Morphology and age cohorts of Pachygrapsus marmoratus (Grapsidae) in the southern Mediterranean Sea. International Research Journal of Natural Sciences, 10 (3). pp. 14-32. ISSN 2053-4108(Print), 2053-4116(Online)

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Abstract

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.

Item Type: Article
Subjects: Q Science > QH Natural history
Depositing User: Professor Mark T. Owen
Date Deposited: 16 Oct 2022 10:39
Last Modified: 16 Oct 2022 10:39
URI: https://tudr.org/id/eprint/1105

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