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.

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 structure and reproduction of the hermit crab Dardanus deformis (Anomura: Diogenidae) in the Indian Ocean

2005 ◽  
Vol 85 (4) ◽  
pp. 883-887 ◽  
Author(s):  
Carlos Litulo
Keyword(s):  
Population Structure ◽  
Indian Ocean ◽  
Hermit Crab ◽  
Reproductive Activity ◽  
Female Size ◽  
Frequency Distributions ◽  
High Incidence ◽  
Egg Number ◽  
The Indian Ocean ◽  
Continuous Reproduction

The population structure and fecundity of the hermit crab Dardanus deformis were studied. Monthly samples were obtained between January and December 2003 at Costa do Sol, Maputo Bay, southern Mozambique. A total of 604 individuals was analysed of which 273 were males, 164 non-ovigerous females and 167 ovigerous females. The overall size–frequency distributions were unimodal, with males reaching larger sizes than both ovigerous and non-ovigerous females. Females were slightly more abundant than males, but the overall sex ratio did not differ significantly from 1:1. Dardanus deformis showed continuous reproduction throughout the study period. A small number of juveniles was obtained, suggesting that recruitment may take place in a different habitat than that occupied by the adults. The egg number increased with female size, and the high incidence of ovigerous females, may suggest a higher reproductive activity probably as a result of the rapid embryonic development in the study area.

scholarly journals Seasonal variations in the population biology of Salmostoma bacaila (Cyprinidae) from a tributary of the Payra River, Bangladesh

2019 ◽  
pp. 113-119
Author(s):  
Ahamed Ahamed ◽  
Faruque Ahmed Zoarder ◽  
Jun Ohtomi
Keyword(s):  
Sex Ratio ◽  
Seasonal Variations ◽  
Population Biology ◽  
Sexual Maturity ◽  
Condition Factor ◽  
Gonadosomatic Index ◽  
Spawning Season ◽  
Frequency Distributions ◽  
Size At Sexual Maturity ◽  
Management And Conservation

Some biological parameters of Salmostoma bacaila – including sex ratio, length-frequency distributions (LFDs), size at sexual maturity, spawning season, length-weight relationships (LWRs) and condition factor – were studied. Samples were collected seasonally during June 2017 to May 2018 from a tributary of the Payra River. The overall sex ratio was significantly different from the expected value of 1:1 (p < 0.001), in favour of male specimens. Females were significantly larger than males. Size at sexual maturity was estimated at 7.6~7.7 cm total length. Seasonal variations in the gonadosomatic index (GSI) indicate that the main spawning season is from spring to summer. The LWRs showed negative allometric growth in both sexes, but with clear seasonal variation. Fulton’s condition factor varied in both sexes and was attributed to variations in GSI with maturity. The fin¬dings of this study will be helpful for management and conservation of S. bacaila populations.

Sexual dimorphism of the major chela and sex ratio as indicators of the mating system in the estuarine snapping shrimp Alpheus colombiensis Wicksten, 1988 (Decapoda: Caridea: Alpheidae)

2020 ◽  
Vol 40 (6) ◽  
pp. 649-656
Author(s):  
Juan C Azofeifa-Solano ◽  
Jeffrey A Sibaja-Cordero ◽  
Ingo S Wehrtmann
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Sex Ratio ◽  
Mating System ◽  
Mate Guarding ◽  
Female Size ◽  
Monogamous Species ◽  
Low Degree ◽  
Adult Sex Ratio ◽  
Snapping Shrimps

Abstract The sexual selection over traits that favor access to mating partners could promote the emergence of sexual dimorphism when the pressure is different between sexes. Monogamous species are considered to have a low degree of sexual dimorphism. The highly diverse snapping shrimps are usually regarded as monogamous, but the mating system has been studied only in few species. We aimed to provide insights into the mating system and sexual dimorphism of Alpheus colombiensisWicksten, 1988. The adult sex ratio was female biased, and solitary ovigerous females were found, suggesting a temporary mate guarding type of mating system. Our results also revealed sexual dimorphism on the snapping claw, which is larger in males than in females. The male’s snapping claw is probably under sexual selection, which can be mediated by male-male competition or female choice. We also estimated the A. colombiensis female size at maturity at 5.2 ± 0.76 mm. Our results contradict the common idea that snapping shrimps are monogamous species, and support that A. colombiensis probably have a temporary mate guarding (e.g., males can sexually interact with more than one female, in opposition to sexual monogamy). This study also sustains the growing evidence that alpheid shrimps display snapping claw sexual dimorphism.

A population study of Galathea intermedia (Crustacea: Decapoda: Anomura) in the German Bight

2003 ◽  
Vol 83 (1) ◽  
pp. 133-141 ◽  
Author(s):  
Katrin Kronenberger ◽  
Michael Türkay
Keyword(s):  
Sex Ratio ◽  
Population Biology ◽  
Abdominal Segment ◽  
Morphological Characters ◽  
Adult Males ◽  
Length Frequency ◽  
Relative Growth ◽  
Frequency Distributions ◽  
Squat Lobster ◽  
Growth And Reproduction

The objectives of this study were to assess population biology and dynamics of the squat lobster Galathea intermedia. On the basis of nearly regular monthly samples taken with a 2-m beam trawl in the Helgoland trench (HTR) during the period of 1985 until 1992, sex ratio, length composition, relative growth and reproduction were studied. The overall sex ratio deviates significantly from 1:1 with 1[male ]:1·8[female] (P[les ]0·001). On average, sexes are equally large, but adult females attain a slightly larger size than adult males. No sex-specific differences in the length–weight relationship were found. Relative growth of the first abdominal segment is clearly of sexual-dimorphic character. On the basis of the length–frequency distributions, the life cycle of the HTR population lasts between one and two years. According to the appearance of ovigerous females and juveniles, reproduction and recruitment are clearly seasonal. Recruitment takes place between July and December. The main reproduction begins in April and ends in September, with a peak between June and August. A significant increase of specimens showing both male and female morphological characters, referred to as morphological hermaphrodites (P[les ]0·001), and males (P[les ]0·05) respectively, was detected.

The Tasmanian Whitebait, Lovettia seali (Johnston), and the Whitebait Fishery

1950 ◽  
Vol 1 (2) ◽  
pp. 155 ◽  
Author(s):  
M Blackburn
Keyword(s):  
Growth Rate ◽  
Sexual Dimorphism ◽  
Sex Ratio ◽  
Incubation Period ◽  
Standard Length ◽  
Southern Population ◽  
History Of ◽  
One Year

The biology of the aplochitonid Lovettia seali (Johnston), which comprises over 95 per cent. of the Tasmanian whitebait catch, has been studied. Over 78,000 fish from 95 samples were sexed and measured, and 1,200 were classified as to maturity, pigmentation stages, and the presence or absence of food in the stomach. Vertebra counts were made for 1,200 specimens, and there were other observations upon smaller amounts of material. There are marked resemblances to other salmonoids in most points of the biology. There is conspicuous sexual dimorphism. The fish are anadromous and at their ascent are all mature or almost so, and all of the same age (one year by otoliths). After spawning begins there is progressive discoloration and emaciation, followed almost invariably by death. About 0.001 per cent. of the stock consists of two-year fish. The eggs are large compared with the size of fish (extremes of standard length in the adult stock are 33 and 70 mm.) and the incubation period is about three weeks. The larvae drift downstream to the sea. Sex ratio is highly variable, but generally the males greatly outnumber the females. A northern and a southern population can be distinguished, the differences being in growth rate and pigmentation. Each population supports a separate fishery, which operates on the ascending shoals. The history of the fisheries is outlined. The southern fishery has never been important because the fish available at the principal fishing locality are excessively pigmented. More suitable fish could be taken by operating further downstream, where the fish are typically at an earlier stage of maturity. The northern fishery has been vigorously prosecuted and overfishing was probably the cause of the decline in abundance of stock in 1947 and 1948. If there was overfishing, it operated purely by excessive removal of reproducers. The order of the optimum catch is empirically identified and a programme for the management of the stock, aiming at its rehabilitation, is recommended.

Population biology and growth of three sympatric species of intertidal hermit crabs in south-eastern Brazil

2000 ◽  
Vol 80 (6) ◽  
pp. 1061-1069 ◽  
Author(s):  
Alexander Turra ◽  
Fosca P.P. Leite
Keyword(s):  
Population Growth ◽  
Hermit Crab ◽  
Population Biology ◽  
Size Structure ◽  
Growth Function ◽  
Sympatric Species ◽  
Growth Patterns ◽  
Hermit Crabs ◽  
South Eastern ◽  
Eastern Brazil

Hermit crab populations have been described in different habitats and latitudes but few studies focused on coexisting populations. Such information is especially important to evaluate the effect of coexistence in the population biology of such organisms. This study was done in the intertidal region of Pernambuco Islet, São Sebastião Channel, south-eastern Brazil. Random samples of crabs were taken monthly during one year to evaluate their size and sex. The three coexisting Clibanarius populations (C. antillensis, C. sclopetarius, and C. vittatus) showed similar patterns of sex ratio (skewed for females), sexual dimorphism (males larger than females), recruitment (February to June) and population growth but differed in size structure (Cs>Cv>Ca) and reproductive activity over the year. Population growth was estimated using the von Bertalanffy growth function (VBGF) and revealed that the growth of these three populations was strongly reduced from August to January and that longevity varied from 42 to 48 months. Clibanarius antillensis showed continuous reproduction with high frequency of ovigerous females over the year while C. sclopetarius and C. vittatus had a reproductive peak in April and absence of ovigerous females in August/September. Coexistence seemed to influence population biology of these hermit crabs, given the relationship of their reproductive periods and growth patterns to the shell adequacy to the crabs. The overlap in reproductive peaks and recruitment periods may strengthen competition for shells. Comparisons of the reproductive patterns of the hermit crab populations recorded to date emphasize that reproduction and, consequently, life strategies of hermit crabs are not directly dependent on taxonomic or geographical proximity, but on their evolutionary histories and on local processes acting on each assemblage or population.

Population and reproductive biology of the fiddler crab Uca chlorophthalmus (Brachyura: Ocypodidae) from Inhaca Island, southern Mozambique

2006 ◽  
Vol 86 (4) ◽  
pp. 737-742 ◽  
Author(s):  
Carlos Litulo
Keyword(s):  
Sex Ratio ◽  
Geographical Distribution ◽  
Brood Size ◽  
Population Biology ◽  
Reproductive Output ◽  
Fiddler Crab ◽  
Female Size ◽  
Size Distributions ◽  
Reproductive Patterns ◽  
Linear Correlations

This study aimed to assess the population biology and reproduction of the fiddler crab Uca chlorophthalmus at its limit of geographical distribution, Saco da Inhaca mangrove, southern Mozambique. Monthly samples were conducted at low tide periods between January and December 2003. The size distributions showed uni- and bimodal patterns, with males reaching larger sizes than ovigerous and non-ovigerous females. Females were slightly more abundant than males, but the overall sex ratio (1:1.01) did not differ significantly from 1:1. Uca chlorophthalmus displays continuous reproductive patterns with peaks of breeding in March and December. Moreover, linear correlations revealed that breeding in this crab is controlled by both temperature and rainfall. Similarly, juvenile recruitment was constant, but was more intense in winter (May–July). Brood size was positively associated with female size. Timing of the observed breeding pattern in the study area may enhance reproductive output and recruitment of the species.

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.

scholarly journals STRUKTUR UKURAN DAN BIOLOGI POPULASI RAJUNGAN (Portunus pelagicus Linnaeus, 1758) DI PERAIRAN KEPULAUAN ARU

2018 ◽  
Vol 1 (1) ◽  
pp. 51
Author(s):  
Duranta Diandria Kembaren ◽  
Adi Surahman
Keyword(s):  
Population Biology ◽  
Size Structure ◽  
Carapace Width ◽  
Total Mortality ◽  
Swimming Crab ◽  
Fishing Mortality ◽  
Portunus Pelagicus ◽  
Precautionary Approach ◽  
Exploitation Rate ◽  
Average Size

Penelitian struktur ukuran dan biologi populasi rajungan di perairan Kepulauan Aru telah dilakukan pada Januari-April, Juni dan Agustus-November 2016. Penelitian ini bertujuan untuk mengidentifikasi struktur ukuran dan biologi populasi yang meliputi pertumbuhan, laju kematian, dan tingkat eksploitasi rajungan. Pemahaman struktur ukuran dan biologi populasi dapat dijadikan dasar masukan untuk pengelolaan perikanan. Rata-rata ukuran lebar karapas rajungan yang tertangkap sebesar 136 mm untuk jantan dan 141 mm untuk betina. Rajungan yang tertangkap pada Januari dan Juni memiliki rata-rata ukuran yang lebih besar. Rata-rata rajungan yang tertangkap sudah melawati ukuran matang gonad (Lc = 133,4 mm > Lm = 119,9 mm). Puncak musim pemijahan terjadi pada Februari-Maret dan Agustus-September. Lebar karapas asimtosis (CW) sebesar 185 mm dengan laju pertumbuhan (K) 1,15 tahun-1 serta laju kematian total (Z) 4,94 tahun-1, laju kematian alamiah (M) 1,20 tahun-1 serta laju kematian akibat penangkapan (F) 3,74 tahun-1. Laju eksploitasi sudah berada pada kondisi lebih tangkap (E=0,76). Hasil kajian menyarankan bahwa pengelolaan perikanan rajungan perlu dilakukan secara hati-hati agar sumberdaya ini dapat lestari. Salah satu upaya yang dapat di tempuh adalah dengan menerapkan sistem penutupan musim penangkapan rajungan pada saat terjadinya puncak musim pemijahan yaitu pada Februari-Maret dan Agustus-September. Dengan demikian diharapkan proses regenerasi dan rekrutmen rajungan selalu dapat mendukung ketersedian stok sumberdaya rajungan di perairan Kepulauan Aru ini. Study on the size structure and population biology of blue swimming crab in the waters of Kepualuan Aru was conducted in January to April, June and August to November 2016. The aim of this study was to identify the size structure and population biology i.e. growth, mortality, and exploitation rate of blue swimming crab. Understanding on the size structure and population biology can be used as basic information for managing blue swimming crab fisheries.  Average size of carapace width of blue swimming crab was 136 mm for male and 141 mm for female. Catch on January and June  was bigger size than others months. Length at first capture was higher than length at maturity (Lc = 133,4 mm > Lm = 119,9 mm). Spawning peak season occurs in  February-March and August-September. Asymptotic carapace width (CW) of blue swimming crab was 185 mm with the growth rate (K) was 1,20 year-1, total mortality (Z) was 4,94 year-1, natural mortality (M) was 1,20 year-1, and fishing mortality (F) was 3,74 year-1. Exploitation rate was exceed the sustainability limit (E = 0,76). Thus, it is needed to manage the blue swimming crab fishery with precautionary approach. Based on this study, we suggest to apply the fishing closure system at the peak of spawning season. Thus, the regeneration process and recruitment will support the availability of blue swimming crabs resource in Kepualuan Aru waters.

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