scholarly journals Population biology of the crab Armases angustipes (Crustacea, Decapoda, Sesarmidae) at Brazilian tropical coast

2014 ◽  
Vol 104 (2) ◽  
pp. 150-161 ◽  
Author(s):  
Marina de Sá Leitão C. de Araújo ◽  
Deusinete de O. Tenório ◽  
Daniela da S. Castiglioni
Keyword(s):  
Population Structure ◽  
Sexual Dimorphism ◽  
Sex Ratio ◽  
Population Biology ◽  
Carapace Width ◽  
Reproductive Activity ◽  
Coastal Regions ◽  
Phytoplankton Productivity ◽  
Number Of Individuals ◽  
Tropical Coast

The semi terrestrial crabs are important elements of the fauna of coastal regions. The aim of this study was to analyze the population structure of Armases angustipes (Dana, 1852) at estuaries of the Ariquindá River, considered a non impacted area, and Mamucabas River, considered a few impacted area, on the south coast of state of Pernambuco, Brazil. The species occurred in all months of the year. The number of individuals per month varied, being higher in the months of transition between the seasons. This is probably due to significant seasonal variations of air and burrow temperature and burrow salinity. There was no sexual dimorphism in size of A. angustipes in the mangrove of Ariquindá River, but males were larger than females in the mangrove of Mamucabas River. In both estuaries, the sex ratio did not differ from Mendelian proportion, but showed a deviation for females. The analysis of temporal variation in sex ratio showed significant differences in some months of the year. These variations are due to cyclical events that act distinctly on each sex. In both estuaries, size classes of carapace width were equally represented by both sexes. The ovigerous females of A. angustipes occurred only in some months of the year, especially in summer, in both estuaries. Probably the high phytoplankton productivity observed in summer favors the reproductive activity, since these algae serve as food for the larvae. Specimens of the population of Rio Ariquindá are largest and wider than those of Mamucabas River. This fact, associated with the low abundance of crabs and the lower frequency of ovigerous females observed in Mamucabas River, is an indication that this population may be influenced by the environmental impacts that this estuary has received.

Population biology and fecundity of the Indo-Pacific hermit crab Clibanarius longitarsus (Anomura: Diogenidae)

2005 ◽  
Vol 85 (1) ◽  
pp. 121-125 ◽  
Author(s):  
Carlos Litulo
Keyword(s):  
Sexual Dimorphism ◽  
Sex Ratio ◽  
Hermit Crab ◽  
Population Biology ◽  
Size Structure ◽  
Reproductive Activity ◽  
Female Size ◽  
Frequency Distributions ◽  
One Year ◽  
Average Size

The population biology and reproduction of the hermit crab Clibanarius longitarsus were studied with emphasis on size structure, sex ratio, breeding season and fecundity. Specimens were sampled monthly over a period of one year (January–December 2003) at Costa do Sol mangrove, Maputo Bay, southern Mozambique. A total of 597 individuals was obtained of which 202 were males, 192 non-ovigerous females and 203 ovigerous females. Annual size–frequency distributions were polymodal for males and bimodal for non-ovigerous and ovigerous females, respectively. Sexual dimorphism was recorded by the larger average size attained by males in relation to females. Sex ratio was female-biased during most months of the study. Clibanarius longitarsus showed a higher reproductive activity with two major peaks (March and October). Juvenile recruitment was continuous throughout the study period. Clutch size was positively associated with female size. The high number of ovigerous females as obtained in the present population may evidence a higher reproductive activity displayed by C. longitarsus at Costa do Sol mangrove.

Population dynamics of Sesarma rectum (Crustacea: Brachyura: Grapsidae) in the Ariquindá River mangrove, north-east of Brazil

2011 ◽  
Vol 91 (7) ◽  
pp. 1395-1401 ◽  
Author(s):  
Daniela da Silva Castiglioni ◽  
Paloma Joana Albuquerque de Oliveira ◽  
Josivan Soares da Silva ◽  
Petrônio Alves Coelho
Keyword(s):  
Sex Ratio ◽  
Sexual Maturity ◽  
Carapace Width ◽  
Reproductive Activity ◽  
Reproductive Period ◽  
Size Class ◽  
Adult Males ◽  
North East ◽  
Class Frequency ◽  
Autumn And Winter

This study was carried out in order to provide basic information on the population ecology of the crab Sesarma rectum in the Ariquindá River mangrove, Tamandaré, State of Pernambuco, Brazil. The population was analysed with regard to the following aspects, in particular: the size-class frequency distribution of carapace width (CW), mean body size (CW) of males and females, morphological sexual maturity, sex-ratio, reproductive period, and recruitment. Samples were collected monthly from April 2008 through to March 2009; the crabs were collected manually, with a capture effort by one person for 30 minutes, during low tide. The specimens obtained were measured for CW, length of the propodus of males, and abdomen width of females; and the sex and ovigerous condition were noted. Altogether, we obtained 511 specimens (132 juvenile and 137 adult males, and 171 juvenile and 71 adult females, of which 32 were ovigerous). The median CW of males (16.15 mm) was significantly larger than that of females (13.82 mm) (P < 0.05). The size at morphological sexual maturity was 15.73 mm in males and 16.71 mm in females. The sex-ratio for the total of specimens analysed was 1.11:1 (male:female) (P > 0.05). The sex-ratio by size-class showed an anomalous pattern, with a greater abundance of males in the larger size-classes. The reproductive period was continuous and the highest frequency of ovigerous females was recorded in the spring and summer. The major pulse of recruitment occurred during autumn and winter, which is related to greater reproductive activity during the warmer months of the year.

scholarly journals Population Structure and Reproductive Biology of the Endangered Crab Deiratonotus japonicus (Brachyura, Camptandriidae) Surveyed for Nine Years in the Kita River, Japan

2020 ◽  
Vol 8 (11) ◽  
pp. 921
Author(s):  
Il-Kweun Oh ◽  
Seung-Woo Lee
Keyword(s):  
Population Structure ◽  
Sex Ratio ◽  
Reproductive Biology ◽  
Carapace Width ◽  
River Mouth ◽  
Sampling Period ◽  
Sampling Station ◽  
Egg Number ◽  
Kanagawa Prefecture ◽  
The Mean

Deiratonotus japonicus (D. japonicus) is known as a near-threatened species, because of the changing conditions of its habitat. This species resides in isolated locations and in upstream, brackish waters from Kanagawa Prefecture to Okinawa Prefecture in Japan. In this study, we investigated the population structure and reproductive biology of D. japonicus in the Kita River, Japan. The distribution, sex ratio, breeding season, and fecundity were assessed at bimonthly intervals during spring low-tide periods from May 2001 to November 2008 and from November 2014 to January 2016 for approximately nine years. A total of 3525 crabs were collected during the sampling period: 1806 (51.2%) males, 1240 (35.2%) non-ovigerous females, and 479 (13.6%) ovigerous females. The overall sex ratio (1:0.95) did not differ significantly from the expected 1:1 ratio. The mean maximum density was 26.1 and 36.5 indiv./m2 for the first and second sampling periods, respectively, in the sampling station 5.2 km from the Kita River mouth, and all individuals were typically found approximately 4.4–6.8 km (13.2 ± 7.8 indiv./m2) from the Kita River mouth. Carapace width (CW) ranged from 2.6 to 13.5 mm in males and from 2.8 to 13.4 mm in females and was significantly different between the two sexes (p < 0.05). Ovigerous females were found almost throughout the entire sampling period, with breeding peaks between July and September. The smallest ovigerous female had a CW of 3.9 mm. The seasonal frequency distribution suggested the continuous recruitment of young juveniles (CW < 3.9 mm) throughout the year, with peaks from September to November. The mean fecundity was 1008.3 ± 183.1 (8.3 ± 1.6 mm) eggs. Egg number in relation to CW was calculated by the formula egg number (EN) = 110.36 × CW + 90.96 (R2 = 0.948, n = 41, p < 0.0001). Regression analysis showed that fecundity was closely associated with female CW. Our results indicate that the performance of reproductive biology depends not only on continuous breeding but also on recruitment throughout the year in our study area.

Comparative morphology of the Euphrates soft-shelled turtle, Rafetus euphraticus (Daudin, 1802) (Reptilia, Testudines) in Southeastern Anatolia

1998 ◽  
Vol 19 (3) ◽  
pp. 281-291 ◽  
Author(s):  
Ertan TaŞkavak
Keyword(s):  
Sexual Dimorphism ◽  
Sex Ratio ◽  
Carapace Length ◽  
Carapace Width ◽  
Comparative Morphology ◽  
Head Width ◽  
Morphometric Measurements ◽  
Allopatric Populations ◽  
The Past

AbstractMorphometric measurements and ratios were recorded in Euphrates soft-shelled turtles, Rafetus euphraticus, sampled in the Euphrates and Tigris rivers and tributaries, Southeastern Anatolia. According to nine morphometric ratios, there are clear differences between two allopatric populations of R. euphraticus, the specimens of the Tigris population being much flatter and having a wider carapace as compared with the Euphrates population. Male:female sex ratio was 2.7:1, no sexual dimorphism was present in the morphometric ratios. Rafetus euphraticus and Trionyx triunguis, which were considered congeneric in the past, differed from each other in the ratios of the carapace length/carapace width, carapace length/plane of the greatest carapace width, carapace length/plastron length, carapace length/rostrum length, carapace width/plastron length, carapace width/head width and plastron length/rostrum length.

scholarly journals Population characteristics of the house rat (Rattus rattus) in rural areas of Pothwar, Pakistan

2021 ◽  
pp. 110-115
Author(s):  
Surrya Khanam ◽  
Muhammad Mushtaq
Keyword(s):  
Sex Ratio ◽  
Rural Areas ◽  
Population Biology ◽  
Control Strategies ◽  
Rattus Rattus ◽  
Age Groups ◽  
Reproductive Activity ◽  
Population Characteristics ◽  
Four Seasons ◽  
Suitable Environment

The house rat (Rattus rattus) is the major commensal rodent species present in rural habitats of Pakistan. Little is known about the biology of this species in the country. Hence, proper control plans for its management could not be developed. The objective of the present study was to determine the population biology of the house rat in rural commensal habitats of Pothwar, Pakistan. A two-year study was conducted in four villages during four seasons. A total of 217 house rats were captured with snap traps. The species had an unbiased sex ratio. Individuals from different age groups were present in the population, and the adults outnumbered sub-adults and juveniles. Reproductive activity was observed throughout the year, and reproductively active individuals outnumbered the inactive ones. These results show that rural commensal habitats were providing suitable environment for the house rats throughout the year. The findings of the present study will be useful for the planning of control strategies in the commensal habitats of rural Pothwar.

Population structure of Emys orbicularis in the Bardello (Po Delta, Northern Italy)

1995 ◽  
Vol 16 (1) ◽  
pp. 77-85 ◽  
Author(s):  
Stefano Mazzotti
Keyword(s):  
Population Structure ◽  
Sexual Dimorphism ◽  
Sex Ratio ◽  
Population Size ◽  
Carapace Length ◽  
Shell Height ◽  
Northern Italy ◽  
Emys Orbicularis ◽  
Frequency Distributions ◽  
Po Delta

AbstractA population of Emys orbicularis in the Bardello (Po Delta, Northern Italy) was studied for 3 years using capture-mark-recapture methods, 23.6% of which were male, 57,5% female and 18.9% were juvenile specimens. The sex ratio of 127 specimens was 1:2. Certain morphometric variables such as the carapace length and shell height were examined in order to establish their sexual dimorphism. The population structure was defined by means of frequency distributions of carapace length. Using the Lincoln-Petersen and Jolly-Seber indices it was possible to estimate the population size as an average of 7.2 specimens per hectare.

scholarly journals Sexual dimorphism and associated population characteristics in the benthopelagic shrimp Pasiphaea sivado (Crustacea: Caridea: Pasiphaeidae)

2017 ◽  
Vol 81 (1) ◽  
pp. 57
Author(s):  
Daniela Silveira Simão ◽  
José Luís Pérez Gil ◽  
Pere Abelló
Keyword(s):  
Sexual Dimorphism ◽  
Sex Ratio ◽  
Population Biology ◽  
Critical Size ◽  
Gender Segregation ◽  
Western Mediterranean ◽  
Population Characteristics ◽  
Male Dominance ◽  
Mediterranean Populations ◽  
First Time

Morphological and size dimorphism between genders of the benthopelagic shrimp Pasiphaea sivado are reported for the first time in the present work. All five pleopod protopods of females are thinner and more elongated than the male pleopod protopods, which in turn are anteriorly rounded and have robust shapes. The shape variability of the second pleopod protopods was also analysed using geometric morphometrics techniques which clearly differentiated between the thinner, elongated shape of the females and the robust shape of males. An important application of the observations of sexual dimorphism in pleopod shape in adult P. sivado is, from now on, the ability to quickly assess the gender of individuals when fisheries and population biology studies are carried out in the field unaided by a magnifying. A critical size from which the population sex ratio biases changed from female to male dominance was found in all studied western Mediterranean populations of P. sivado. This critical size different and became progressively smaller from populations in the Alboran Sea to populations in the Catalan Sea. Concerning sex ratio, no significant tendency of gender segregation was found across the bathymetric distribution range of the species, suggesting that this species does not perform differential depth distribution by gender.

scholarly journals Morphometric characteristics of crayfish, Cherax gherardiae, from Maybrat, West Papua, Indonesia

2018 ◽  
Vol 26 (4) ◽  
pp. 223-230
Author(s):  
Yulianus Sedik ◽  
Dominggus Rumahlatu ◽  
Bambang Irawan ◽  
Agoes Soegianto
Keyword(s):  
Sexual Dimorphism ◽  
Sex Ratio ◽  
Carapace Length ◽  
Condition Factor ◽  
Carapace Width ◽  
Allometric Growth ◽  
Morphometric Characteristics ◽  
Significant Difference ◽  
West Papua ◽  
Males And Females

Abstract The objectives of this study were to determine the length-weight relationships (LWRs), chelae length (ChL)-width (ChW) relationships, carapace length (CL)-width (CW) relationships, sexual dimorphism, and condition factor (K) of Cherax gherardiae from Maybrat, West Papua Indonesia. The sex ratio of C. gherardiae was found to be 1.04:1. The LWRs for males, females, and all individuals were W = 0.225L1.96, W = 0.181L2.02, and W = 0.187L2.03, respectively. Males and females exhibited negative allometric growth (b<3). There was no significant difference in lengths between males and females; however, the weight of males was greater than that of females. The K values for males, females, and all individuals were 3.17, 3.09, and 3.13, respectively. The ChL of the crayfish ranged from 1.0 to 7.5 cm, and the ChW ranged from 0.4 to 2.5 cm. The CL of crayfish ranged from 1.6 to 6.0 cm, and the CW ranged from 0.6 to 4.1 cm. Males had longer chelae and carapaces than did females. There was no significant difference in chelae width or carapace width between males and females. The ChL-ChW relationships for males, females, and all individuals were ChW = 0.312ChL + 0.260, ChW = 0.397ChL - 0.050, and ChW = 0.345ChL + 0.119, respectively. The CL-CW relationships for males, females, and all individuals were CW = 0.750CL-0.955, CW = 0.526CL - 0.178, and CW = 0.635CL-0.543, respectively.

scholarly journals Population biology of Uca mordax (Smith, 1870) (Crustacea, Decapoda, Ocypodidae) from the southeastern coast of Brazil

2009 ◽  
Vol 31 (73/75) ◽  
Author(s):  
Vivian Fransozo ◽  
Rafael Campanelli Mortari ◽  
Aline Staskowian Benetti
Keyword(s):  
Sex Ratio ◽  
Population Biology ◽  
Sexual Maturity ◽  
Fiddler Crab ◽  
Carapace Width ◽  
Southeastern Coast ◽  
Size Classes ◽  
Median Size ◽  
Size At Sexual Maturity ◽  
Males And Females

The population biology of the fiddler crab Uca mordax (Smith, 1870) was investigated in an estuarinemangrove from the southeastern coast of Brazil. Samplings were monthly performed by 2 collectors for30 min. using the technique of capture per unit effort during low tide periods. The allometric techniquewas used to determine crab size at sexual maturity (males and females). Thus, specimens were classified into juveniles and adults according to their size at sexual maturity for each sex. The specimens weredistributed into size classes. Recruitment was based on the juvenile frequency and the reproduction peakin ovigerous females. The median size of males was 15.9 ± 2.7 mm carapace width (CW) (n = 557) andthat of females, 14.6 ± 2.8 mm CW (n = 528). At sexual maturity, size of crabs was 11.9 mm CW formales and 11.5 mm CW for females. Juveniles were found throughout the year but more frequently inthe winter and autumn. Sex ratio did not differ among seasons, except during the summer (p < 0.05).As regards sex ratio per size class, females predominated in the fi rst size classes. Reproduction peakwas observed in the summer. In short, the population biology of U. mordax was similar to that of mostbroad-front fi ddler crab species.

Dynamique de la population d'Orchestia mediterranea L. (Crustacé, Amphipode) dans l'estuaire du Bou Regreg (Maroc)

1985 ◽  
Vol 63 (12) ◽  
pp. 2800-2809 ◽  
Author(s):  
B. Elkaïm ◽  
J. P. Irlinger ◽  
S. Pichard
Keyword(s):  
Population Structure ◽  
Statistical Analysis ◽  
Sex Ratio ◽  
Population Ecology ◽  
Seasonal Variations ◽  
Reproductive Potential ◽  
Reproductive Activity ◽  
Brood Number ◽  
Complex Manner ◽  
Adaptative Strategy

Some aspects of the population ecology of Orchestia mediterranea, found in the estuary of Bou Regreg (Morocco), were studied over the course of 1 year. Histograms of cohort frequency and observations on reproductive activity showed seasonal variations all year long: O. mediterranea can be characterized as a multivoltine, semiannual species. By statistical analysis, associated with a procedure near successive maxima, the population structure was determined by identifying cohorts that are associated in a complex manner. All these characteristics are similar to those of O. mediterranea and Talorchestia deshayesei found in the Mediterranean Sea. The exceptionally high annual reproductive potential estimated from the fecundity (which varies with the age of females and with the seasons), the sex ratio, and the brood number of the successive cohorts from the same filiation, all in a nutrient-rich environment, suggests an r type of adaptative strategy.

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