Gonadal cycle of the blue crab Portunus segnis (Forskål, 1775) (Decapoda, Portunoidea) in the Mediterranean Sea off Alexandria, Egypt

Crustaceana ◽  
2021 ◽  
Vol 94 (1) ◽  
pp. 1-27
Author(s):  
Ibrahim Gaber ◽  
Mauro Luisetto ◽  
Oleg Latyshev
Keyword(s):  
Mediterranean Sea ◽  
Germ Cells ◽  
Vas Deferens ◽  
Gonadosomatic Index ◽  
Sex Ratios ◽  
Stage Iv ◽  
Hepatosomatic Index ◽  
Chi Square ◽  
The Mediterranean ◽  
Portunus Segnis

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.

scholarly journals Sex ratios of juvenile loggerhead sea turtles Caretta caretta in the Mediterranean Sea

2006 ◽  
Vol 324 ◽  
pp. 281-285 ◽  
Author(s):  
P Casale ◽  
B Lazar ◽  
S Pont ◽  
J Tomás ◽  
N Zizzo ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Sea Turtles ◽  
Sex Ratios ◽  
Caretta Caretta ◽  
Loggerhead Sea Turtles ◽  
The Mediterranean

Gonadal development in males of the orange mud crab, Scylla olivacea (Herbst, 1796) (Decapoda, Brachyura, Portunidae)

Crustaceana ◽  
2017 ◽  
Vol 90 (1) ◽  
pp. 1-19 ◽  
Author(s):  
K. Waiho ◽  
H. Fazhan ◽  
S. Jasmani ◽  
M. Ikhwanuddin
Keyword(s):  
Germ Cells ◽  
Reproductive System ◽  
Vas Deferens ◽  
Gonadosomatic Index ◽  
Gonadal Development ◽  
Gonad Maturation ◽  
Mud Crab ◽  
Maturation Stages ◽  
Histological Characteristics

This study describes the morphological and histological characteristics of the male reproductive system of the orange mud crab, Scylla olivacea (Herbst, 1796). Three maturation stages were determined on the basis of the vas deferens diameter, the gonad colour and the gonadosomatic index (GSI). Significant differences were observed in the GSI value as the crabs matured. All germ cells were present in the histological sections of the testes, and these decrease significantly in size as they progress from spermatogonia, spermatocytes, and spermatids to spermatozoa. Spermatophores are found in the anterior vas deferens (AVD) and median vas deferens (MVD) of all maturation stages but not in the posterior vas deferens (PVD), with a significantly smaller size in immature and maturing specimens. Thus, the classification of S. olivacea gonads into various maturation stages based solely on histological characteristics (i.e., the presence of spermatophores) is impossible. Therefore, the combination of both microscopic and macroscopic features is essential for determining the gonad maturation stages of male S. olivacea.

scholarly journals Differences in flowering sex ratios between native and invasive populations of the seagrass Halophila stipulacea

2018 ◽  
Vol 61 (4) ◽  
pp. 337-342 ◽  
Author(s):  
Hung Manh Nguyen ◽  
Periklis Kleitou ◽  
Demetris Kletou ◽  
Yuval Sapir ◽  
Gidon Winters
Keyword(s):  
Sex Ratio ◽  
Mediterranean Sea ◽  
Red Sea ◽  
Sex Ratios ◽  
Dioecious Plants ◽  
Halophila Stipulacea ◽  
The Mediterranean ◽  
Northern Red Sea ◽  
Rare Group

Abstract Deviations from the 1:1 sex ratio are common in dioecious plants. The tropical seagrass Halophila stipulacea is among an extremely rare group of dioecious plants that are widely recognized as female-biased. Here we report on differences in sex ratios between native (Eilat, northern Red Sea) and invasive (Cyprus, Mediterranean Sea) populations. While H. stipulacea populations were female-biased in their native region, invasive populations were either male- or female-biased. The existence of both sexes simultaneously in the Mediterranean invasive populations might help its ongoing expansion in the Mediterranean, thereby threatening local seagrasses species.

scholarly journals Reproduction and seasonal occurrence of the copper shark, Carcharhinus brachyurus, from north Patagonia, Argentina

2005 ◽  
Vol 62 (1) ◽  
pp. 107-115 ◽  
Author(s):  
Luis O. Lucifora ◽  
Roberto C. Menni ◽  
Alicia H. Escalante
Keyword(s):  
Gonadosomatic Index ◽  
Sex Ratios ◽  
Ovarian Follicles ◽  
Nursery Area ◽  
Seasonal Occurrence ◽  
Maximum Diameter ◽  
Hepatosomatic Index ◽  
Size At Maturity ◽  
Adult Males ◽  
Adult Females

Abstract The copper shark, Carcharhinus brachyurus, is the only member of its genus with a preferred habitat in temperate waters, and it usually gives birth in the cooler extremes of its range. Maturation patterns, reproductive condition, monthly sex ratios, and seasonal occurrence of copper sharks were analysed, mostly from Anegada Bay (Argentina), a presumed nursery area for the species. Males mature between 200 and 220 cm total length (LT), with a 50% size at maturity (L50) of 216.18 cm LT. Females mature between 215 and 223 cm LT (with an L50 of 222.16 cm LT). Maturity off Argentina is at a slightly smaller size than off South Africa and Australia. There is no sexual dimorphism in size at maturity. Only two pregnant females, each carrying 16 advanced embryos, were caught. The hepatosomatic index (IH) of adult males showed significant monthly changes, related possibly to an increase in the gonadosomatic index (IG). IH and IG of adult females showed no significant trend throughout the fishing season. The IH of adult females was significantly correlated with maximum diameter of ovarian follicles. Small translucent ovarian follicles in two gravid females indicated that ovarian and gestation cycles run sequentially, with maturation of oocytes subsequent to parturition. Neither newborns nor significant numbers of females bearing term embryos were recorded, and there was no evidence of a copper shark primary nursery area in Anegada Bay. However, most copper sharks in Anegada Bay were large juveniles and sub-adults. The species is found off Argentina from October to late March, but they do not move southwards to Anegada Bay until December, and they leave the bay again by April. These movements appear to be related more to water temperature rather than to migration of potential prey. Monthly variation in sex ratios is associated mainly with fluctuations in the sex ratios of juveniles.

sexual maturity, fecundity and embryonic development of the spiny dogfish, squalus acanthias, in the eastern mediterranean sea

2005 ◽  
Vol 85 (5) ◽  
pp. 1155-1161 ◽  
Author(s):  
archontia chatzispyrou ◽  
persefoni megalofonou
Keyword(s):  
Mediterranean Sea ◽  
Eastern Mediterranean ◽  
Gonadosomatic Index ◽  
Squalus Acanthias ◽  
Minimum Size ◽  
Hepatosomatic Index ◽  
Spiny Dogfish ◽  
Female Fish ◽  
Eastern Mediterranean Sea ◽  
Gravid Females

the reproductive biology of the spiny dogfish, squalus acanthias, was investigated throughout a year, in the eastern mediterranean sea. one hundred and eighty specimens were sampled of which 119 were females and 61 males, ranging from 320 to 755 mm and from 350 to 820 mm total length (tl), respectively. the minimum size of mature females was 515 mm and 470 mm tl for mature males (smaller compared with sizes in other studies). gonadosomatic index (gsi) and hepatosomatic index (hsi) were higher during june and august in female dogfish, respectively; in males gsi had a peak in july and hsi showed its highest value in april. a total of 39 gravid females was identified with tl ranging between 570 and 755 mm. only 28 of them were bearing embryos; candled uteri were observed in the 11 other gravid animals. a positive relationship was recorded between maternal length and litter size. ovarian fecundity ranged between 1 and 6 (mean 2.1±1.1); uterine fecundity ranged from 1 to 6 (mean 3.3±1.2). the size of the pups varied from 72 to 220 mm tl and their weight ranged between 1.6–48.5 g (mean 11.7±8.6). the spiny dogfish was compared with fish from other study areas and was found to be smaller in size in the eastern mediterranean sea, reaching maturity at smaller sizes and obtaining lower fecundity than female fish in other areas.

Some aspects of the reproductive biology of albacore Thunnus alalunga from the western Mediterranean Sea

2015 ◽  
Vol 95 (8) ◽  
pp. 1705-1715 ◽  
Author(s):  
Sámar Saber ◽  
Josetxu Ortiz de Urbina ◽  
María José Gómez-Vives ◽  
David Macías
Keyword(s):  
Mediterranean Sea ◽  
Reproductive Biology ◽  
Gonadosomatic Index ◽  
Fork Length ◽  
Western Mediterranean ◽  
Minimum Length ◽  
Mediterranean Population ◽  
Western Mediterranean Sea ◽  
Thunnus Alalunga ◽  
The Mediterranean

Thunnus alalunga is an important commercial tuna species widely distributed in the three major oceans and the Mediterranean Sea. The Mediterranean population is currently classified as a data-poor stock and little is known about its basic life history parameters. This study provides the first detailed information on some aspects of the reproductive biology of T. alalunga from the western Mediterranean Sea. A total of 16 104 specimens were measured between 2005 and 2012. The overall sex ratio of females to males was 1.1:1, although the ratio was female biased in fish <70 cm fork length (LF) and male biased in those >75 cm LF. Histological analysis of the ovaries (N = 587) and the monthly variation of the gonadosomatic index for both sexes showed that spawning occurred from June to August, which is a much shorter period than the 7 months reported for T. alalunga in tropical oceanic waters. Thunnus alalunga caught during June and July are capable of spawning daily. The gonadosomatic index values for T. alalunga from the western Mediterranean were up to eight times higher than those of T. alalunga from other oceans. Histological examination of the ovaries showed that the minimum length at sexual maturity of females was 56 cm LF, which is considerably smaller than those estimated for other stocks.

Aeromonas dhakensis pneumonia and sepsis in a neonate Risso’s dolphin Grampus griseus from the Mediterranean Sea

2015 ◽  
Vol 116 (1) ◽  
pp. 69-74 ◽  
Author(s):  
L Pérez ◽  
ML Abarca ◽  
F Latif-Eugenín ◽  
R Beaz-Hidalgo ◽  
MJ Figueras ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Grampus Griseus ◽  
The Mediterranean ◽  
Risso's Dolphin
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