On the occurrence of three exotic decapods, Callinectes sapidus (Portunidae), Portunus segnis (Portunidae), and Trachysalambria palaestinensis (Penaeidae), in northern Tunisia, with updates on the distribution of the two invasive portunids in the Mediterranean Sea

Abstract Adults of Portunus segnis were captured from Ras el Tin beach on the Mediterranean Sea at Alexandria, Egypt, from January to December 2017. Male crabs are present in higher density in the sea during fall and winter, while female crabs are more common during spring and summer. Sex ratios were calculated as follows: number of males or females/total number of crabs. The calculated sex ratios were subjected to a Chi-square test according to the equation: , where O represents the observed frequency and E the expected frequency. One-way analysis of variance shows differences in the carapace size (length and width) and the weight of males and females during the four seasons. The hepatosomatic index of male crabs ranges from 9.1-9.25 in winter months, 8.7-7.9 in fall, being lower, 3.12-2.25, in spring and 5.96-4.13 in summer. The hepatosomatic index of female crabs is 8.9-3.9 in spring, 9.2-7.9 in summer, shifts lower to 5.1-3.2 in fall and to 4.2-1.5 in winter. The gonadosomatic index of female crabs is 0.12-8.2 in spring, 0.20-13.9 in summer and decreases to 0.66-7.8 in fall and 0.18-4.7 in winter. Ovaries and testes were isolated, fixed, and prepared for histological examination. The testicular lobes are surrounded by simple epithelium with haemolymph filling the interspaces. Seminiferous ducts are inserted in the testicular lobes. Spermatogenesis and spermiogenesis are described. The vas deferens is usually filled with spermatophores. Spermatophore formation begins in the testis near the vas deferens. Near the base of the penes there is glandular tissue. This study proposes the classification of the ovarian maturation into five stages: Stage I, Immature ovary with primary and secondary oogonia; Stage II, early maturing ovary with germ cells in different maturation phases; Stage III, mature ovary with vitellogenic oocytes and germ cells; Stage IV, maturing ovary with oocytes I, II and fully mature oocytes; and Stage V, ovary in regeneration. The wall of the spermatheca consists of a stratified squamous epithelium.

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Filling the gap on Italian records of an invasive species

Acta Adriatica ◽

10.32582/aa.62.1.8 ◽

2021 ◽

Vol 62 (1) ◽

pp. 99-104

Author(s):

Francesco Tiralongo ◽

Guido Villani ◽

Roberto Arciprete ◽

Emanuele Mancini

Keyword(s):

Invasive Species ◽

Mediterranean Sea ◽

Callinectes Sapidus ◽

Tyrrhenian Sea ◽

Mediterranean Areas ◽

The Mediterranean ◽

Italian Coasts

Callinectes sapidus is considered one of the worst invasive species in the Mediterranean Sea. After its first observation in 1948, the species has colonized several Mediterranean areas. In this work, we report the first records of the species in Latium and Campania (northern-central and central Tyrrhenian Sea respectively), filling a gap in its distribution along the Italian coasts. We also provide a review of Italian records.

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Determination of size selectivity of traps for blue crab (Callinectes sapidus Rathbun, 1896) in the Mediterranean Sea

Tarım Bilimleri Dergisi ◽

10.1501/tarimbil_0000001327 ◽

2015 ◽

Vol 21 (2) ◽

pp. 256-261

Author(s):

ÖZDEMİR Süleyman; GÖKÇE

Keyword(s):

Mediterranean Sea ◽

Blue Crab ◽

Callinectes Sapidus ◽

Size Selectivity ◽

The Mediterranean

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Seasonal and diel changes in the structure of a crustacean decapod assemblage associated to a shallow Cymodocea nodosa meadow in northern Tunisia (Mediterranean Sea). An overview of the Mediterranean decapod taxocoenoses.

Mediterranean Marine Science ◽

10.12681/mms.346 ◽

2013 ◽

Vol 15 (1) ◽

pp. 59 ◽

Cited By ~ 4

Author(s):

A. DAOULATI ◽

M. ANTIT ◽

A. AZZOUNA ◽

J. E. GARCIA RASO

Keyword(s):

Mediterranean Sea ◽

Reproductive Strategies ◽

Time Lag ◽

Early Summer ◽

Cymodocea Nodosa ◽

Total Abundance ◽

Northern Tunisia ◽

Significant Relationships ◽

The Mediterranean ◽

Summer Minimum

A study on the decapod assemblage inhabiting a shallow meadow of Cymodocea nodosa from the bay of La Goulette (Tunisia) was carried from February 2009 to February 2010. Monthly samples (with replicates) were taken in the morning and at night, with a small Agassiz trawl. In total 11699 specimens belonging to 41 species were caught. Significant day-night and seasonal changes are mainly related to movements (feeding) and recruitments. Higher abundance and richness were reported at night. Analyses rendered no significant relationships between the plant phenology and abundances and richness; neither between the total abundance and temperature, but significant correlations with a time lag of 3 - 4 months between these factors exist, which could be related with hatching and larval development period. The nocturnal and diurnal values in the diversity and equitability indexes are quite similar along the year (peaks in spring - early summer, minimum in autumn - early winter). This pattern is mainly due to the strong dominance of a few species, with maximum abundances during their recruitment events, whose seasonal and day-night changes have been determined. Besides, an overview of the decapods assemblage associated to this seagrass for the Mediterranean Sea has been carried out. The species can be divided into two groups (linked to the leaves and to the sediment). The differences in species composition between areas must be related to different sampling methodologies, feeding and reproductive strategies, but also to the layout and influence of the surrounding habitats.

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