The fiddler crab, Uca bengali Crane, 1975: population biology and burrow characteristics on a riverbank in southern Thailand

Crustaceana ◽  
2015 ◽  
Vol 88 (7-8) ◽  
pp. 791-807 ◽  
Author(s):  
Fahmida Wazed Tina ◽  
Mullica Jaroensutasinee ◽  
Onprang Sutthakiet ◽  
Krisanadej Jaroensutasinee
Keyword(s):  
Organic Matter ◽  
Body Size ◽  
Sex Ratio ◽  
Moisture Content ◽  
Population Biology ◽  
Fiddler Crab ◽  
Tidal River ◽  
Southern Thailand ◽  
Percent Moisture ◽  
Crab Density

We studied the population structure ofUca bengaliCrane, 1975 (crab density, sex ratio, and body size (i.e., carapace length and width, major claw length and width)), along with burrow characteristics (diameter, length, depth, and volume) as well as sediment characteristics (percent moisture content and organic matter) along a bank gradient at three distances (2, 4 and 6 m) from the edge of a tidal river. The results showed no differences in crab density, sex ratio, and body size among the three distances. The percent moisture content at 2 m distance was higher than at 4 and 6 m, and the percentage organic matter at 2 m distance was higher than at 6 m distance. Burrows were shorter in length, shallower in depth, and smaller in volume at 2 m distance, but these measures increased with increasing distance from the river edge. Both males and females made three distinct burrow shapes: I, J and U; the J-shaped burrows were the most numerous at all distances.

‘Photography’ as a useful method for estimating the density, sex-ratio and body size of the surface-active Austruca perplexa (H. Milne Edwards, 1852) (Brachyura, Ocypodidae)

Crustaceana ◽  
2021 ◽  
Vol 94 (11-12) ◽  
pp. 1429-1440
Author(s):  
Kanitta Keeratipattarakarn ◽  
Fahmida Wazed Tina ◽  
Rattapon Sangngam ◽  
Ketsanee Thongsri ◽  
Arreeya Suphap
Keyword(s):  
Body Size ◽  
Sex Ratio ◽  
Fiddler Crab ◽  
Body Sizes ◽  
Crab Density ◽  
Surface Active ◽  
Non Destructive ◽  
Photography Method

Abstract Estimations of crab density, sex-ratio, and body sizes are difficult. Though the ‘burrow excavation’ method is widely used to estimate these parameters in surface-active crabs, it is destructive to crab populations. Therefore, an alternative, non-destructive method is desirable. This study compared the non-destructive ‘photography’ method with the ‘burrow excavation’ method in a fiddler crab (Austruca perplexa (H. Milne Edwards, 1852)) population. Twenty 0.25 m2 quadrats were set out and 4 photos were taken of the surface-active crabs in each quadrat. All crab burrows were then excavated, and the crabs were collected to estimate their numbers, sexes, and body and claw sizes. Afterward, the photographs were analysed to estimate the same parameters by using the GIMP program. These parameters were then compared between the two methods. The results showed that these parameters were not different between the methods compared. This study thus reveals that the ‘photography’ method could safely be used instead of the ‘burrow excavation’ method, and yield the same results.

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 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.

Variable sex-specific mortality due to shorebird predation on a fiddler crab

2003 ◽  
Vol 81 (7) ◽  
pp. 1209-1221 ◽  
Author(s):  
Pablo D Ribeiro ◽  
Oscar O Iribarne ◽  
Luciano Jaureguy ◽  
Diego Navarro ◽  
Eugenia Bogazzi
Keyword(s):  
Sex Ratio ◽  
Fiddler Crab ◽  
Dry Mass ◽  
High Density ◽  
Migratory Shorebirds ◽  
Specific Mortality ◽  
Crab Density ◽  
Feeding Activities ◽  
Golden Plover ◽  
Uca Uruguayensis

Male fiddler crabs compete for access to mates mainly by displaying an enlarged claw. One cost of this large claw is presumed to be higher exposure to predators. The fiddler crab Uca uruguayensis is used as a food source by several Neotropical migratory shorebirds. We investigated whether crab density and male claw-waving behaviour increase predation by shorebirds. The sex ratio of crabs on the surface was strongly male biased. Male crabs showed a daily succession of feeding–waving–feeding activities and their dry mass at the site decreased with a high density of crabs, suggesting stronger male–male competition than at sites with a low density of crabs. Sex-specific predation varied according to shorebird species. The Ruddy Turnstone (Arenaria interpres) preyed intensively on male crabs when they were courting and at sites with a high density of crabs, the Black-bellied Plover (Pluvialis squatarola) and the Lesser Golden Plover (Pluvialis dominica) preyed on crabs of both sexes, and the Whimbrel (Numenius phaeopus) foraged intensively on females. When estimating the net effect of all predators, we found that the four shorebird species together were able to consume between 0.1 and 0.2% of the crab population, and consumption did not differ between the sexes of crabs. These mortality rates indicate a low source of mortality, likely unable to produce deviations in the sex ratio of the population. Thus, our results indicate that a trait thought to be sexually selected does not necessarily lead to a disproportionate increase in mortality due to predation.

Effects of Non-uniform Kernel Moisture Content on Moisture Measurement of Corn

2005 ◽  
Vol 1 (1) ◽  
pp. 77-93
Author(s):  
Bíborka Gillay ◽  
David B. Funk
Keyword(s):  
Moisture Content ◽  
Moisture Measurement ◽  
Safe Storage ◽  
Grain Moisture ◽  
Moisture Meter ◽  
Percent Moisture ◽  
New Crop ◽  
The U.S

The price paid for corn is usually based on 15.0 or 15.5 percent moisture content. However, corn must be dried below 13 percent moisture to ensure safe storage for a year or more. In the U.S., such stored corn cannot be directly remoistened before selling it, but it can be mixed with moist new-crop corn. Accurate moisture measurement of mixtures of dry and moist corn is important to permit adjustment of blending ratios to maximize profitability, but grain moisture meters are less accurate for mixtures of wet and dry grain. This research evaluated the differences between dielectric-type moisture meter results for mixed and equilibrated corn samples at different moisture levels and different measurement frequencies. Equilibrated grain samples tended to give lower moisture results than recently mixed grain samples - especially in the 1 to 10 MHz region. These differences permitted detection of mixtures by using moisture measurements at two frequencies.

Multi-algorithm comparison to predict soil organic matter and soil moisture content from cell phone images

Geoderma ◽  
2021 ◽  
Vol 385 ◽  
pp. 114863
Author(s):  
Perry Taneja ◽  
Hitesh Kumar Vasava ◽  
Prasad Daggupati ◽  
Asim Biswas
Keyword(s):  
Organic Matter ◽  
Soil Moisture ◽  
Soil Organic Matter ◽  
Moisture Content ◽  
Cell Phone ◽  
Soil Moisture Content ◽  
Algorithm Comparison

Methyl mercury in zooplankton—the role of size, habitat, and food quality

2002 ◽  
Vol 59 (10) ◽  
pp. 1606-1615 ◽  
Author(s):  
Martin Kainz ◽  
Marc Lucotte ◽  
Christopher C Parrish
Keyword(s):  
Organic Matter ◽  
Fatty Acid ◽  
Body Size ◽  
Methyl Mercury ◽  
Size Fraction ◽  
Food Sources ◽  
Calanoid Copepods ◽  
Bacterial Food

Pathways of methyl mercury (MeHg) accumulation in zooplankton include ingestion of organic matter (OM). We analyzed fatty acid (FA) biomarkers in zooplankton to (i) investigate the effect of allochthonous and autochthonous OM ingestion on MeHg concentrations ([MeHg]) in zooplankton and (ii) examine how algal and bacterial food sources affect MeHg bioaccumulation. We partitioned bulk zooplankton samples (i.e., >500, 202, 100, and 53 μm) from Lake Lusignan (Québec) and measured [MeHg] and [FA] in each fraction. [MeHg] increased with increasing body size and was significantly higher in pelagic than in littoral macrozooplankton (>500 μm). The amount of the ingested terrestrial FA biomarker 24:0 indicated that less than 1% of the total FA in zooplankton was derived from allochthonous sources. More than 60% of the ingested FA originated from algal biomarkers and <10% from bacterial biomarkers. Relative amounts of algal-derived essential FA and bacterial FA were not associated with [MeHg] in any size fraction. In pelagic zones, the amount of MeHg in zooplankton related positively to the number of large organisms such as Calanoid copepods and Daphnia. We propose that the accumulation of MeHg in lacustrine zooplankton depends on the zooplankton habitat rather than on the quality of ingested food.

II.—Hidden Divergence in Laboratory Strains of Drosophila pseudo-obscura

1944 ◽  
Vol 62 (1) ◽  
pp. 9-19 ◽  
Author(s):  
Rowena Lamy
Keyword(s):  
Body Size ◽  
Sex Ratio ◽  
Genetic Constitution ◽  
Low Grade ◽  
Testis Size ◽  
Hybrid Female ◽  
Back Cross ◽  
Pure Race ◽  
Range Of Variation

The Race A/Race B hybrid females of D. pseudo-obscura have a high percentage of fertility, comparable with that of females of pure race. The number and viability of their offspring, however, are largely affected by the genetic constitution of the hybrid female as well as by that of the male to which she is mated in the backcross. Hence the performance of any given hybrid is determined in the first instance by the actual strains of the pure races which are used in making the P1 racial cross. Generally speaking the results are of the same order whenever the same strains are used. The progenies of hybrid females of different genetic constitution may differ in three main aspects: (1) The total number of offspring may be comparable with that usually obtained in a pure race cross; it may be reduced to any extent; in certain matings it is consistently at zero. (2) The sex ratio may be completely normal or male-deficient or female-deficient in any degree; completely uni-sexual progenies are sometimes obtained. (The above observations are mainly in agreement with reports of earlier writers; cf. Lancefield, 1929, Dobzhansky, 1936, Mampell, 1941, Sturtevant, 1937.) (3) “Viability characters,” i.e. those affecting general vigour and physical normality, may be of a high or a low grade; some progenies are comparable in this respect with the pure race, the only exception being that they show a much greater range of variation in body-size of both sexes, and in the testis size of males, abnormalities which are common to all back-cross progenies whatever the genetic constitution of the mother or father. Some progenies show in addition deformities of a peculiar type usually affecting the abdomen and occasionally the legs and wings.

Variation in Weight, Size, and Sex Ratio of Coccinellid Adults (Coleoptera: Coccinellidae)

1966 ◽  
Vol 98 (6) ◽  
pp. 639-644 ◽  
Author(s):  
B. C. Smith
Keyword(s):  
Body Size ◽  
Sex Ratio ◽  
Water Content ◽  
Food Supply ◽  
Sexual Differences ◽  
Intraspecies Variation ◽  
Food Scarcity ◽  
Food Requirement ◽  
Males And Females

AbstractThe weight and size of coccinellid adults varied with species, sex, and feeding. Intraspecies variation in weight was generally similar in the eight species studied. Females were more variable than males in body size. Females of some species were heavier and larger than males, and species can be classified on a basis of difference in the weight and size of the sexes.An increase in the food supply after a period of food scarcity affected the sex ratio, as the minimum food requirement of females was greater than males. Females increased in weight more rapidly than males after feeding. The availability of food in the field affected the weight and size of some species. Adult water content was influenced by feeding but not by sex or the quantity of food given to the larva.Males were more abundant in species with small sexual differences in weight and size. The degree of difference in weight and size between males and females may be used as a criterion to select species that are best adapted to survive when food is scarce.

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.

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