Fiddler crab

An incidence of bopyrid isopod infestation was observed in giant freshwater prawn, Macrobrachium rosenbergii (de Man) juveniles (40-60 mm/0.9-1.5 g) in a scampi culture farm in East Godavari district of Andhra Pradesh. The presence of parasite was observed by conspicuous boil like swelling of the branchial chamber where the parasite was found lodged on the gills. The infested gill was highly compressed and necrosed. Only one branchial chamber was infested by the parasite while the other gill was normal. The infested prawns were thin and emaciated and showed retarded growth. The parasite was identified as Probopyrus bithynis (Richardson, 1904) which caused inhibition of ventilation due to its permanent lodging in the branchial chamber and impaired the gaseous exchange by gills. It was also observed that this parasite caused parasitic castration in the infested prawns.

Several times within the teleost fish order Tetraodontiformes singular jaw adducting muscles have been effectively ‘duplicated’ by physical subdivision to produce new muscles. This morphological system provides an opportunity to investigate how the functional complexity of muscular systems changes with evolutionary increases in the number of component muscles. In this study we asked if muscle duplication has lead to functional diversification by comparing the motor patterns of muscles that result from subdivision events. The activity patterns of five different sets of duplicated muscles were quantified with electromyographic recordings (EMG) from four individuals in each of three species during processing of three prey types. Prey varied in durability and elusiveness (live fiddler crabs, pieces of squid tentacle and live paeneid shrimps). For each cycle of prey processing, measurements were made of the relative onset time of each adductor muscle, the duration of each burst of activi...

We compared seasonal changes in population structures and surface activities in the fiddler crab Uca arcuata between temperate (Yoshinogawa, Japan) and subtropical localities (Shinko, Japan). At Yoshinogawa, male courtship behavior was observed from April to July and pair formation from May to July, whereas at Shinko such mating behavior patterns were observed over two periods (June to September and February to March). Thus, the subtropical population appears to have a longer breeding period than the temperate population. Waving occurred from June to August at Yoshinogawa and during all months (except October and November) at Shinko. Waving frequency was higher during courting periods at all localities, although lower at Shinko compared with Yoshinogawa. Maximum body size and the size at maturity were smaller at Shinko than at Yoshinogawa. Surface and underground couplings were observed at Yoshinogawa, whereas only surface coupling was observed at Shinko. These differences and similarities are discussed from the viewpoint of habitat conditions and population characteristics.

and Taiwan . Chimneys are commonly found at the burrow entrances of some individuals (Fig. ). There have been two ecological and behavioral studies of this species: Murai (1992) on courtship activity and on population structure and life history, neither of which dealt with chimneys. Published information on chimneys of this species is a brief note by mentioning that chimney burrows are owned by both sexes, young as well as adults, and giving an example of the building process. This paper describes chimney building in Uca arcuata. The sex and body size of chimney builders were examined, as were the seasonal changes in chimney abundance. We experimentally examined the function of chimneys by releasing crabs near burrows with and without chimneys to determine whether chimneys act to protect burrows from intruders. Study Site and Period.-We studied a population of Uca arcuata in the estuary of the Katsuura River, Tokushima Prefecture, Japan (34°1′N, 134°35′E) between 22 April and 15 October 1996. All work was carried out on a 150 m 2 muddy flat in the middle to upper intertidal zone, where U. arcuata were abundant.

The Deepwater Horizon oil spill was the largest marine oil spill in US waters to date and one of the largest worldwide. Impacts of this spill on salt marsh vegetation have been well documented, although impacts on marsh macroinvertebrates have received less attention. To examine impacts of the oil spill on an important marsh invertebrate and ecosystem engineer, we conducted a meta-analysis on fiddler crabs (Uca spp.) using published sources and newly available Natural Resources Damage Assessment (NRDA) and Gulf of Mexico Research Initiative (GoMRI) data. Fiddler crabs influence marsh ecosystem structure and function through their burrowing and feeding activities and are key prey for a number of marsh and estuarine predators. We tested the hypothesis that the spill affected fiddler crab burrow density (crab abundance), burrow diameter (crab size), and crab species composition. Averaged across multiple studies, sites, and years, our synthesis revealed a negative effect of oiling on all three metrics. Burrow densities were reduced by 39 % in oiled sites, with impacts and incomplete recovery observed over 2010-2014. Burrow diameters were reduced from 2010 to 2011, but appeared to have recovered by 2012. Fiddler crab species composition was altered through at least 2013 and only returned to reference conditions where marsh vegetation recovered, via restoration planting in one case. Given the spatial and temporal extent of data analyzed, this synthesis provides compelling evidence that the Deepwater Horizon spill suppressed populations of fiddler crabs in oiled marshes, likely affecting other ecosystem attributes, including marsh productivity, marsh soil characteristics, and associated predators.

Ecological functions of bioturbation in ecosystems have received increasing attention over the recent decades, and crab burrowing has been considered as one of the major bioturbations affecting the physical and chemical processes in salt marshes. This study assessed the integrated effects of crab excavating and burrow mimic trapping on sediment turnover and vertical C and N distributions in a Chinese salt marsh in the Yangtze River estuary. Crab burrowing increased soil water content and the turnover of carbon and nitrogen and decreased bulk soil density. Vertical movement of materials, nutrient cycling and reuse driven by crab burrowing might be obstructed by vegetation (Phragmites australis and Spartina alterniflora communities). The amount of soil excavated by crab burrowing was higher than that deposited into burrow mimics. In Phragmites marshes, Spartina marshes and unvegetated mudflats, net transport of soil to the marsh surface was 171.73, 109.54, and 374.95 g m -2 d -1 , respectively; and the corresponding estimated soil turnover time was 2.89, 4.07 and 1.83 years, respectively. Crab burrowing in salt marshes can mix surface and deeper soil over a period of years, accelerating litter decomposition and promoting the efficient reuse of nutrients by plants. Therefore, bioturbation affects soil physical processes and functioning of ecosystems, and needs to be addressed in ecosystem management.

Fiddler crabs burrow creates oxic-anoxic interfaces on the burrow walls. Accordingly burrow walls represent the transitions site between oxic and anoxic condition where the sediment properties varied significantly across it. In this study the burrows of three species of fiddler crabs including Uca rosea, Uca forcipata and Uca pardussumieri were sampled at three depth layers. Sediment properties of burrow walls including; temperature, redox potential, pH, density, porosity, water content, organic content, chlorophyll content and solid phase iron pools were measured to determine the magnitude of burrow effects on mangrove sediments. The results indicated that U. paradussumieri effectively reduced the sediment porosity of surrounding sediments down to 45%. Oxidized layer was more extended around U. paradussumieri burrows. Burrow walls of U. forcipata and U. paradussumieri contain higher water content than ambient sediment and burrows of U. rosea efficiently decreased the organic content of sediment. The PCA biplots indicated that the burrow walls of the all three species of fiddler crabs at 3 and 8 cm depth were correlated with oxidized iron. Ambient sediments of U. forcipata habitat were correlated with reduced iron and organic content. At 20 cm depth, burrow walls of U. paradussumieri were highly correlated with water content, while ambient sediment was correlated with reduced iron. The results of this study revealed that the thickness of oxidized layer varied according to sediment depth and burrow volume. Consequently the burrow effect varied significantly among different species of fiddler crabs as results of different habitat characteristics, sediment types and crab size.

Waterborne chemicals can be habitat cues for pelagic larvae of benthic invertebrates by stimulating settlement and metamorphosis. Less clear is whether cue effectiveness declines with increasing distance from the source. We examined whether the ability of seawater to stimulate metamorphosis (molting) of fiddler crab Uca minax megalopae to the first-crab stage is restricted to water overlying marshes. Laboratory-reared megalopae were enclosed in situ for 3 d within nylon mesh cages in both a marsh and a river site 15 m away from the marsh. Even in the absence of contact with sediment, megalopae in the marsh had high rates of molting, whereas those in the river molted at very low rates similar to control megalopae enclosed in glass jars containing filtered seawater and deployed in the marsh habitat. In a second experiment, we tested for a dose-dependent molting response from the presumed source of the cue. We hypothesized a negative linear relationship in molting frequency with increasing distance from the marsh. Megalopae were enclosed for 3 d in cages within the marsh and at distances of 2, 5, and 15 m away from the marsh edge, and in jars within the marsh. Molting response was greatest in the marsh, intermediate 2 and 5 m away from the marsh, and lowest 15 m from the marsh and in the control jars (test of regression slope, F 1, 25 = 13.290, p = 0.001, r 2 = 0.321). Therefore, chemical cues for molting of fiddler crab megalopae originate in marshes and decline in effectiveness within a short (<15 m) distance of the marsh habitat.

The United States Army's transformation from the Army of Excellence design to the Modular design had profound changes for the corps organization. The pending transformation of the 3d Armored Cavalry Regiment to a Stryker brigade combat team raised the issue of a corps ability to conduct reconnaissance and security without a dedicated land-based organization. This study addresses a corps requirement to have a dedicated means to gather information and protect the force through the criteria of doctrine, capability and organization. The main findings indicated a corps need for a dedicated reconnaissance and security organization. The U.S. Army's experience in Cambodia in 1970 and Kuwait in 1991 demonstrated the importance of a reconnaissance and security organization to corps and divisions. Regardless of the terrain or weather conditions, the armored cavalry regiments located the enemy and developed the situation through contact. The Army's experience in Iraq in 2003 highlighted the impact a corps faced by operating without a reconnaissance and security force. Modular corps will face similar difficulties in shaping the battlefield for its subordinate units without a dedicated land-based reconnaissance and security organization.

This study was carried out on the behaviour of two species of sympatric fiddler crabs on Abi estuary, Bandar Abbas, Iran. Species differences in activity level, grooming, burrowing, muddy structure construction and feeding were all related to their habitat and food source. The more common Uca annulipes lives in low muddy areas along the edges of small streams while Uca sindensis lives in small patches on the higher areas with sandier sediment. At low tide, both species spent most of their time feeding, while at high tide they retreated into their burrows. Both species frequently walked while feeding and interacted aggressively. There were similarities in the feeding behaviour of these species: they fed at the same times of the tidal cycles, they were more likely to engage in courtship and mating behaviour during February–September and were least aggressive at this time. In both species, crabs excavated mud balls from their burrows and placed them away from their burrow entrances. Th...

Large male fiddler crabs sometimes help smaller neighbours to defend their territories against intruders. These coalitions occur when the helper is likely to defeat the intruder (helper larger than intruder) and the neighbour is likely to lose his territory without help (intruder larger than neighbour). Previous studies of coalitions have excluded males with regenerated claws. Such claws are weaker weapons that make the bearer competitively inferior. Here, we show that male Uca annulipes with regenerated claws are as likely as males with original claws to help their neighbours in territory defence, even though, as weaker males they potentially pay greater costs, being more likely to lose their undefended burrow. We suggest that males with regenerated claws gain greater benefits from retaining a current, small neighbour and that, as in non-coalition fights, the regenerated claw acts as a visual bluff in the early stages of combat. Furthermore, we show that intruders with regenerated or original claws are equally likely to be attacked by a 'helping' neighbour. This bolsters the argument that males cannot visually differentiate between original and regenerated claws.

Colour cues play an important role in sexual selection and conspecific recognition. Literature shows that conspecifics might enjoy their everyday chat, without ever worrying about occasional eavesdroppers (e.g., predators), when information interchange evolves into a private communication channel. Yet, when signalling is converted into foraging cues by predators, their prey must pay the due cost for sustaining conversation. For that matter, fiddler crabs draw attention for having flashy enlarged claws that could potentially attract the attention of many predators. Surprisingly, the costs associated with claw colouration in fiddler crabs are still poorly understood and have never been studied in American species. Here, we initially examine whether hypertrophied claws of American thin-fingered fiddler crabs (Leptuca leptodactyla) reflect UV-light and how conspecific females react to these cues. Then we test two alternative hypotheses concerning the role of claw colouration in fiddler crabs' mate choice: a) that claw

Colour cues play an important role in sexual selection and conspecific recognition. Literature shows that conspecifics might enjoy their everyday chat, without ever worrying about occasional eavesdroppers (e.g., predators), when information interchange evolves into a private communication channel. Yet, when signalling is converted into foraging cues by predators, their prey must pay the due cost for sustaining conversation. For that matter, fiddler crabs draw attention for having flashy enlarged claws that could potentially attract the attention of many predators. Surprisingly, the costs associated with claw colouration in fiddler crabs are still poorly understood and have never been studied in American species. Here, we initially examine whether hypertrophied claws of American thin-fingered fiddler crabs (Leptuca leptodactyla) reflect UV-light and how conspecific females react to these cues. Then we test two alternative hypotheses concerning the role of claw colouration in fiddler ...

1. Measurements of the blood Na concentration and transepithelial electrical potential (T.E.P.) across Uca pugilator acclimated to sea water indicate that Na is maintained out of electrochemical equilibrium with sea water. The resulting net Na influx as well as the sodium gain due to ingestion of the medium must be balanced by extrarenal Na extrusion. 2. The small T.E.P. (-0 7 mV) and the ' transport numbers' of Na and Cl indicate that the permeability to these ions is equivalent. 3. Removal of external K results in a significant stimulation of unidirectional Na efflux that is dependent upon external Na but is not inhibited by ouabain. 4. Transfer of Uca to K and Na-free sea water results in a 54% decline in unidirectional efflux, which is not due to T.E.P. changes. Readdition of 25 mM-K stimulates Na efflux much more than can be accounted for by changes in the T.E.P. Readdition of 25 mM-Na to potassium-free sea water does not change the Na efflux. 5. The results indicate that Na extrusion by Uca is via a Na/K exchange mechanism which partially inhibits Na/Na exchange. Cessation of Na/K exchange (in K-free sea water) removes this inhibition and allows rapid Na/Na exchange. It is not known whether Na/K and Na/Na exchange are via the same or parallel carrier systems.

A new species of fiddler crab (Brachyura: Ocypodidae), Uca boninensis sp. nov., is described from the Ogasawara (Bonin) Islands, Japan. The new species has previously been identified with the widely distributed U. crassipes (White, 1847), from which it differs by having a slightly differently shaped carapace, and relatively stouter male first gonopods (G1). The recognition of the new species is also supported by differences in the mitochondrial cytochrome oxidase I (COI) and control region (CR) genes. U. boninensis sp. nov., appears to be endemic to the Ogasawara Islands, and as the only known population is small, urgent conservation measures are needed for its protection. Our study brings the total number of the Japanese fiddler crab species to 12.

In mangrove ecosystems, litter fall accumulates as refractory organic carbon on the sediment surface and creates anoxic sediment layers. Fiddler crabs, through their burrowing activity, translocate oxygen into the anoxic layers and promote aerobic respiration, iron reduction and nitrification. In this study, the effects of four species of fiddler crabs (Uca triangularis, Uca rosea, Uca forcipata and Uca paradussumieri) on organic content, water content, porosity, redox potential and solid phase iron pools of mangrove sediments were investigated. In each crab's habitat, six cores down to 30 cm depth were taken from burrowed and non-burrowed sampling plots. Redox potential and oxidized iron pools were highest in surface sediment, while porosity, water and organic content were higher in deeper sediment. Reduced iron (Fe (II)) and redox potential were significantly different between burrowed and non-burrowed plots. Crab burrows extend the oxidized surface layer down to 4 cm depth and through the oxidation effect, reduce the organic content of sediments. The effects of burrows varied between the four species based on their shore location. The oxidation effect of burrows enhance the decomposition rate and stimulate iron reduction, which are processes that are expected to play an important role in biogeochemical properties of mangrove sediments.

In tropical regions, different species of fiddler crabs coexist on the mangrove floor, which sometimes makes it difficult to define species-specific habitat by visual inspection. The aim of this study is to find key environmental parameters which affect the distribution of fiddler crabs and to determine the habitats in which each species was most abundant. Crabs were collected from 19 sites within the mudflats of Sepang-Lukut mangrove forest. Temperature, porewater salinity, organic matter, water content, carbon and nitrogen content, porosity, chlorophyll content, pH, redox potential, sediment texture and heavy metals were determined in each 1 m 2 quadrate. Pearson correlation indicated that all sediment properties except pH and redox potential were correlated with sediment grain size. Canonical correspondence analysis (CCA) indicated that Uca paradussumieri was negatively correlated with salinity and redox potential. Sand dwelling species, Uca perplexa and Uca annulipes, were highly dependent on the abundance of 250 μm and 150 μm grain size particles in the sediment. Canonical Discriminative Analysis (CDA) indicated that variation in sediment grain size best explained where each crab species was most abundant. Moreover, U. paradussumieri commonly occupies muddy substrates of low shore, while U. forcipata lives under the shade of mangrove trees. U. annulipes and U. perplexa with the high number of spoon tipped setae on their second maxiliped are specialized to feed on the sandy sediments. U. rosea and U. triangularis are more common on muddy sediment with high sediment density. In conclusion, sediment grain size that influences most sediment properties acts as a main factor responsible for sediment heterogeneity. In this paper, the correlation between fiddler crab species and environmental parameters, as well as the interaction between sediment characteristics, was explained in order to define the important environmental factors in fiddler crab distributions.

The present work used a simulation model to track the movement and fate of oil pollutants, which takes into consideration all the factors of hydrographic and hydrological conditions. The experimental part includes; collect in the bathymetric and topographic data for the study area, measurements of the tides, climate variables, measurements of water velocities, field testing process for a synthetic oil spill and following-up the presence of slicks. The theoretical part simulated the experimental data using MIKE12 HD package for 26 days with the division of semi-dimensions ∆x=200m and ∆y=200m with time step ∆t=80s. This yields to have a number of network j=322 and k=105 equivalent to (6762 km 2). The matching between the field data and the calculated results was up to 90% approximately. The tidal ranges were 4.5m and 4m in Umm Qasr and Khor Al-Zubair, respectively. The speed of the currents during the ebb phase is greater than the speed of the flood in Umm Qasr and Khor Al-Zubair, rea...

The effect of different organic-rich sewage concentration (0%, 20% and 60% diluted in seawater) and absence or presence of mangrove trees on the survival, bioturbation activities and burrow morphology of fiddler crabs species was assessed. After 6 months, males of both species always showed higher survival ($80%) when compared to females ($20%). Crabs inhabiting pristine conditions achieved higher survival (67-87%) than those living in sewage-exposed mesocosms (40-71%). At 60% sewage loading, fiddler crabs processed less sediment (34-46%) during feeding and excavated slightly more sediment (45-80%) than at pristine conditions. While percent volume of the burrow chambers increased (13-66%) at contaminated mesocosms for both vegetation conditions, burrows were shallower ($33%) in bare cells loaded with sewage. The results show that fiddler crabs presented moderate mortality levels in these artificial mangrove wetlands, but mainly in sewage impacted cells. However, they still function as ecosystem engineers through bioturbation activities and burrow construction.

Mangrove forests are known to accomplish crucial ecosystem functions and services. They are nursery areas for fish, prawns and crabs, which provide coastal communities with a variety of food, timber and chemicals, and protect coasts from catastrophic events, such as tsunamis. Recently, a novel ecological service has been proposed for mangrove systems, namely natural wastewater treatment wetlands. This hypothesis was based on experimental data collected mainly in Chinese mangrove systems, which proved that mangrove soils were efficient in absorbing nutrients. Moreover, sewage loading seemed harmless to both plants and benthic communities in these systems. However, before promoting the use of natural mangroves as pollution buffers, or constructed mangrove wetlands as sewage treatment facilities, more data are needed on their overall tolerance to organic loading. Differences in macrobenthos patterns were thus investigated between peri-urban mangroves and sites not affected by sewage disposal in East Africa. We assessed differences in epifaunal assemblages, comprising crabs and molluscs, employing multivariate ACI unbalanced analyses to compare peri-urban mangrove swamps with those characteristic of non-urban mangroves with similar ecological traits. The sampling design was spatially nested, replicates being assessed at equatorial (southern Kenya) and subtropical (southern Mozambique) sites. The results manifested a consistent increase in crab biomass at the peri-urban sites in both Kenya and Mozambique. Moreover, the peri-urban systems were richer than the non-urban mangroves, both in terms of fiddler crabs (Uca spp.) which feed on benthic microalgae and bacteria, and sesarmids, such as Perisesarma guttatum and Neosarmatium meinerti, which feed on both substratum and leaf litter. The abundance of gastropods, in contrast, decreased significantly, especially in Kenya, mainly due to the disappearance of the mud whelk Terebralia palustris. The results thus indicate that, in East African mangrove systems, domestic wastewater has detectable effects on crabs and molluscs, suggesting their usefulness as bioindicators of its effects in mangroves. Transformed benthic patterns at the peri-urban sites indicated the need for further study of the actual potential of natural mangrove forests to absorb pollution in sewage treatment.

Kepiting biola (Uca spp.) memiliki keanekaragaman yang tinggi dan penyebaran yang luas di pesisir pantai terutama daerah tropis dan sub tropis. Eksistensinya dalam ekosistem mudah dikenali karena mempunyai morfologi dimorfisme serta ukuran capitnya yang sangat mencolok. Penelitian ini bertujuan untuk mengetahui kepadatan dua populasi kepiting biola, Uca lactea dan Uca coarcata pada karakteristik biotop berbeda di pesisir pantai Kota Bengkulu. Penelitian ini dilakukan pada bulan Januari sampai dengan April 2016 di Muara Sungai Hitam Kota Bengkulu pada lima titik penelitian yaitu pasir, lumpur, pasir bercampur lumpur, vegetasi bakau dan vegetasi tumbuhan api-api. Sampel diambil dengan menggunakan metode purposive sampling. Analisa kandungan bahan organik dilakukan di BPTP Kota Bengkulu. Dari 5 titik penelitian secara keseluruhan diperoleh kepadatan 1,75 individu/m 2 . Populasi masing-masing Uca berdasarkan karakteristik biotop menunjukan bahwa Uca lactea dominan pada habitat yang ditumbuhi tumbuhan api-api dengan substrat pasir bercampur lumpur, komposisi pasirnya lebih banyak dari lumpur serta memiliki kadar bahan organik yang normal. Sementara itu Uca coarcata mendominasi area berlumpur tanpa vegetasi dengan kandungan organik yang tinggi. Populasi Uca dipengaruhi oleh kondisi substrat maupun kandungan bahan organik dan keberadaan vegetasi pada habitatnya. Uca lactea dan Uca coarcata dalam penelitian ini memiliki kemampuan adaptasi yang berbeda dalam biotop yang berbeda. Kata kunci: bengkulu, biotop, populasi, Uca lactea, Uca coarcata. PENDAHULUAN Crustacea menjadikan kawasan hutan mangrove sebagai tempat tinggal, tempat memijah, tempat mengasuh dan mencari makan. Crustacea seperti remis, udang dan kepiting sangat melimpah di ekosistem mangrove. Salah satu yang ter kenal adalah kepiting lumpur (Thalassina anomala) yang dapat membentuk gundukan tanah besar di mulut liangnya, serta kepiting biola (Uca) yang salah satu capitnya sangat besar. Terdapat sekitar 60 spesies kepiting di ekosistem mangrove. Kebanyakan memakan dedaunan, lainnya memakan alga atau detritus di sedimen tanah dan membuang sisanya dalam gumpalan-gumpalan pelet (Musa, 2010 dalam Alfira, 2014). Kepiting biola (Uca sp.) merupakan salah satu jenis kepiting yang memiliki habitat di daerah interdial, terutama di hutan mangrove dan pantai berpasir. Beberapa jenis kepiting biola ditemukan dalam jumlah yang melimpah dalam habitat mangrove. Kepiting ini ditemukan dipantai 536

The study of mophology, morphometry and alometry of Uca perplexa, one of fiddler crabs that dominated at mangrove vegetation in Pulau Baii of Bengkulu have been conducted. We measured morphometric characters including body weight and sizes of carapace, abdomen, chelae, frontal, eyebrow and eye stalk. The result showed Uca perplexa live at sandy mud substrate and made burrow around mangrove roots. Uca perplexa have back carapace with some horizontal white strips. Carapace was acute and straight at anteriolateral part and rounded at dorsolateral. Their foot color usually brown although some of them were grey, were also found. The male (2.4±0.96 g) has higher of body weight than female (0.77±0.23 g) caused by dimorphism of chelae in male. Carapace width of male and female were 14.74±4.42 mm and 10.42±3.24 mm, respectively. As for abdomen width of male was 5.16±1.61 mm and of female was 6.58±1.38 mm. The length of major chelae was 44.66±9.22 mm as minor chelae was 10.50±0.49 mm. The frontal length of male was 3.44± 0.44 mm as for female was 2.83±0.69 mm. The eyebrows were narrow with eye stalks length for male and female were 6.50±2.46 and 4.20±0.92, respectively. Alometric analysis showed that Uca perplexa either male or female has growth pattern with negative alometry (b<3). It suggest the increase of body weight in Uca perplexa is slower than the increase of size of its carapace, abdomen and chelae.

Fiddler crabs ( Uca spp .) are distributed widely in tropical and subtropical areas in the world. They live in the sandy and muddy bay habitats of intertidal zone. This study aimed to find species abundance, microhabitat and population density of fiddler crabs in mangrove conservation area of Pantai Panjang, Bengkulu.  The sampling was conducted for three months started from December 2013 to February 2014. Sampling locations were decided purposively on the area consist of four microhabitats, i.e. sandy, muddy, muddy around decay plant roots and around mangrove roots. Samples of Uca were collected from 1x1 m of sixty quadrants.   The results found seven species of fiddler crabs i.e. U. perplexa, U. lactea, U. jocelynae, U. forcipata, U. triangularis, U. rosea, and U. dussumieri . They were distributed at four microhabitats. The microhabitats of U. perplexa, U. lactea, U. jocelynae, U. forcipata, U. triangularis, U. rosea, and U. dussumieri were around mangrove roots and sandy, around...

Kepiting biola ( Uca spp.) memiliki keanekaragaman yang tinggi dan penyebaran yang luas di pesisir pantai  terutama daerah tropis dan sub tropis. Eksistensinya dalam ekosistem mudah dikenali karena mempunyai morfologi  dimorfisme serta ukuran capitnya yang sangat mencolok. Penelitian ini bertujuan untuk mengetahui kepadatan dua  populasi kepiting biola, Uca lactea dan Uca coarcata  pada karakteristik biotop berbeda di pesisir pantai Kota  Bengkulu. Penelitian ini dilakukan pada bulan Januari sampai dengan April 2016 di Muara Sungai Hitam Kota  Bengkulu pada lima titik penelitian yaitu pasir, lumpur, pasir bercampur lumpur, vegetasi bakau dan vegetasi  tumbuhan api-api. Sampel diambil dengan menggunakan metode purposive sampling . Analisa kandungan bahan  organik dilakukan di BPTP Kota Bengkulu. Dari 5 titik penelitian secara keseluruhan diperoleh kepadatan 1,75  individu/m 2 . Populasi masing-masing Uca berdasarkan karakteristik biotop menunjukan bahwa Uca lactea dominan pada habita...

Bioturbation is an important process in the soft-bottom ecosystem to return nutrients in the environment. This study aimed to evaluate the effects of bioturbation activities on the growth of mangrove saplings (Rhizophora apiculata). A caging experiment using a total of 16 plots each measuring 1 × 1 m containing two mangrove saplings in each plot (N=32 saplings) with eight caged and eight uncaged plots were placed randomly in Guang-guang, Davao Oriental, Philippines. The set-up was monitored for five months. The length of internode, number of nodes, leaves and length of branches of the saplings were measured and counted. In addition, the number of mounds, holes and fiddler crabs were also counted in the uncaged, marked plots to determine their activities. Result of the comparison of the number of holes, mounds, and fiddler crabs showed high significant differences with the number of holes in the sediment being greater in the uncaged set-ups (holes &gt; mounds = fiddler crab; P&lt;0.0...

Karimunting Village is a coastal area that has a mangrove with contained several faunas in it, one of which is a fiddler crab. The fiddler crab is a Decapoda ordo and it is included in the Ocypodidae family. This study aims to collect data on the diversity of fiddler crabs in Karimunting Village. The method used in this study is a survey, while the sample is collected by applying the transect line with a purposive sampling technique. The transect line is 500 m length, with a total of three lanes. There are ten plots of 1x1 meter in size in each transect lines to pick up fiddler crabs. Fiddler crabs species were found in 6 species, namely Uca paradussumieri, Uca annulipes, Uca forcipata, Uca rosea, Uca crassipes and Uca tetragonon. The Shannon-Winner species diversity index (H&#39;) of fiddler crabs in 1st and 2nd lanes both are categorized medium, while in the 3rd lane is categorized low. The range of values H&#39;=0,3-1,5. The value of species abundance index (Xi) ranges from 3-16....

The relative growth of the fiddler crab Uca sindensis in Pohl Port was studied. Ten 0.5 m 2 quadrates were randomly sampled monthly during low tide periods from October 2009 to September 2010. A total of 840 crabs, 449 (53.45%) males and 391(46.5%) females, were sampled. The Carapace width of males ranged from 5.5 to13.5 mm (mean ± SD) (8.92 ± 2.04), and of females from 5.0 to 11.5 mm (mean ± SD) (7.95 ± 1.34). Carapace height (CH) and Carapace length(CL), height of the major cheliped (HMC) of males, abdomen width of females (AW), major cheliped length (LMC), dactiluse (D), feeding cheliped (CHF) and merouse (M) were employed as dependent variables and carapace width(CW) as independent variable. The relationship between CW × CH was positive in males and females. The equation (Log CH=Log-4.881+4.681LogCW) for males (P&lt;0.05) and Log CH=Log1.882+3.299LogCW for females (P&lt;0.05). The females showed allometric positive growth for CW × AW relation to male (Log AW= Log0.784+1.217Log C...

Distribution, population and reproductive biology of Uca sindensis were studied in a subtropical mangrove of Pohl port in the northern Persian Gulf. Sex ratio, distribution, population structure, handedness (evenness), diameter burrow, breeding season and fecundity were investigated. Ten 0.5 m 2 quadrates were randomly sampled during low tide periods from October 2009 to September 2010.A total of 711 crabs, 344 (47.7%) males and 367(52.3%) females, were sampled. The CW of males ranged from 4 to16 mm and of females from 5 to 17 mm indicating sexual dimorphism. The overall sex ratio was 1:0.93 and did not differ significantly from the expected 1:1 (χ ଶ test, P>0.05), however the monthly sex ratio was different from expected 1:1(χ ଶ test, P<0.05). Results indicated that the size frequency distributions of this species could also be determined through direct analysis of burrow openings (r 2 =0.99). Breeding took place during warm season of April 2009 to September 2010. Egg numbers increased with female size(r 2 =0.50). The regression analysis showed that the number of eggs increased linearly with the increase of carapace width (r 2 = 0.766, EN= 0.1125 CW-0.1129, n=31). It was concluded that two factors of temperature and TOM affected growth and reproduction pattern in U. sindensis.

Fiddler crab females have two small feeding claws while males have only one; the other is enlarged and used as a weapon as well as a mate attraction signal. The study was conducted on the small intertidal fiddler crab Uca sindensis in the Abi estuary near Bandar Abbas on the Persian Gulf. Data were collected from September 2007 to August 2008 in order to cover a wide range of ecological conditions experienced by these crabs over the duration of a year. We considered whether males Uca sindensis have behaviorally or morphologically compensated for the loss of one feeding claw. Therefore we measured the sex ratio of surface-active crabs; the size of the feeding claws the amount of food processed and the feeding effort (male and female). We showed that males scoop up handfuls of sediment at approximately half the rate of females, but spend more time feeding than do females (70.41%). Males are slightly larger than females, but the relationship of feeding claw to carapace size is not linear: small females have relatively large feeding claws for their size, while large males have relatively large feeding claws for their size. Males and females process equivalent amounts of food on a daily basis. In order to compensate for the loss of one feeding claw, males need to spend a greater amount of time feeding.

This study was carried out on the behaviour of two species of sympatric fiddler crabs on Abi estuary, Bandar Abbas, Iran. Species differences in activity level, grooming, burrowing, muddy structure construction and feeding were all related to their habitat and food source. The more common Uca annulipes lives in low muddy areas along the edges of small streams while Uca sindensis lives in small patches on the higher areas with sandier sediment. At low tide, both species spent most of their time feeding, while at high tide they retreated into their burrows. Both species frequently walked while feeding and interacted aggressively. There were similarities in the feeding behaviour of these species: they fed at the same times of the tidal cycles, they were more likely to engage in courtship and mating behaviour during February–September and were least aggressive at this time. In both species, crabs excavated mud balls from their burrows and placed them away from their burrow entrances. Th...

This study was carried out on the behaviour of two species of sympatric fiddler crabs on Abi estuary, Bandar Abbas, Iran. Species differences in activity level, grooming, burrowing, muddy structure construction and feeding were all related to their habitat and food source. The more common Uca annulipes lives in low muddy areas along the edges of small streams while Uca sindensis lives in small patches on the higher areas with sandier sediment. At low tide, both species spent most of their time feeding, while at high tide they retreated into their burrows. Both species frequently walked while feeding and interacted aggressively. There were similarities in the feeding behaviour of these species: they fed at the same times of the tidal cycles, they were more likely to engage in courtship and mating behaviour during February–September and were least aggressive at this time. In both species, crabs excavated mud balls from their burrows and placed them away from their burrow entrances. Th...

Mangrove forests are among the tropical marine ecosystems most severely affected by rapid environmental change and the activities of key associated macrobenthic species contribute to their ecological resilience. Along the east coast of Africa, the amphibious sesarmid crab Neosarmatium africanum (=meinerti) plays a pivotal role in mangrove ecosystem functioning through carbon cycling and sediment bioturbation. In the face of rapid climate change, identifying the sensitivity and vulnerability to global warming of this species is of increasing importance. Based on a latitudinal comparison, we measured the thermal sensitivity of an tropical and a temperate population of N. africanum, testing specimens at the centre and southern limit of its distribution, respectively. We measured metabolic oxygen consumption and haemolymph dissolved oxygen content during air and water breathing within a temperature range that matched the natural environmental conditions. The results indicate different thermal sensitivities in the physiological responses of N. africanum from tropical and temperate populations, especially during air breathing. The differences observed in the thermal physiology between the two populations suggest that the effect of global warming on this important mangrove species may be different under different climate regimes.

The fiddler crab Uca mjoebergi mates both underground in male-defended burrows and on the surface near female-defended burrows. The reproductive tract of Uca species facilitates last-male precedence, suggesting that males that do not guard-mated females are likely to gain very little paternity if the female re-mates with another male. Here, we test the reproductive success of burrow and surface matings using paternity analysis. We found that 100 % of the females that mated in burrows extruded a clutch of eggs. Furthermore, we show conclusively, for the first time in a fiddler crab species, that last-male sperm precedence results in the majority of the female's eggs being fertilised by the burrow-mated male. In contrast, surface matings resulted in significantly fewer females extruding eggs (5.6 %). Paternity analysis also revealed that more than half of the clutches from burrow-mated females showed low levels of extra-pair paternity from previous matings. Although multiple matings appear common in U. mjoebergi, burrow-mated males that guard females are guaranteed a successful mating with extremely high rates of assured paternity. Surface matings therefore appear to be an opportunistic tactic that may increase male reproductive success in a highly competitive environment.

Female mate choice is an important force of sexual selection. Males of countless species have evolved extraordinary traits solely to increase their attractiveness to females. Several factors can, however, affect a female&#39;s degree of choosiness for these traits. Variation in mate choice can have several important evolutionary consequences for both sexes. In this thesis, I examine factors that can influence female mate choice and male mating success in the fiddler crab Uca mjoebergi. Fiddler crabs live in dense, mixed sex colonies where each individual occupies and defends a burrow that is essential for survival. During predator attacks, males and females will retreat quickly into their burrows for safety. I found that time spent in a refuge was highly flexible and strongly dependent on the trade-off between the costs and benefits of hiding in U. mjoebergi. Males and females took longer to re-emerge when foraging opportunities were low. Furthermore, when mating opportunities were ...

1. Signals used during male combat are expected to be honest indicators of fighting ability. However, recent studies show that dishonesty in male signalling is more prevalent than previously believed. Here we show that regenerated (leptochelous) claws in male Uca mjoebergi fiddler crabs are not only dishonest signals of two types of whole-organism performance capacities that are likely to be useful during fights (claw closing force and pull-resisting force), but they are also less effective as weapons in situations where males are unable to bluff. 3. Original (brachychelous) male claws are statistically significant predictors (independent of body size) of both closing force and the force required to pull a male out of a tunnel. By contrast, leptochelous claw size does not convey information on those performance capacities following control for body size. 4. Furthermore, claw size affects fighting ability such that leptochelous residents are at a significant competitive disadvantage to brachychelous residents, although claw type does not affect the ability of non-resident males to win fights. 5. This study is among the first to show that male armaments can dishonestly signal performance traits that are likely important for winning fights, and is the first to show evidence for dishonest signalling of multiple components of fighting ability.

The fiddler crab Uca mjoebergi mates both underground in male-defended burrows and on the surface near female-defended burrows. The reproductive tract of Uca species facilitates last-male precedence, suggesting that males that do not guard-mated females are likely to gain very little paternity if the female re-mates with another male. Here, we test the reproductive success of burrow and surface matings using paternity analysis. We found that 100 % of the females that mated in burrows extruded a clutch of eggs. Furthermore, we show conclusively, for the first time in a fiddler crab species, that last-male sperm precedence results in the majority of the female's eggs being fertilised by the burrow-mated male. In contrast, surface matings resulted in significantly fewer females extruding eggs (5.6 %). Paternity analysis also revealed that more than half of the clutches from burrow-mated females showed low levels of extra-pair paternity from previous matings. Although multiple matings appear common in U. mjoebergi, burrow-mated males that guard females are guaranteed a successful mating with extremely high rates of assured paternity. Surface matings therefore appear to be an opportunistic tactic that may increase male reproductive success in a highly competitive environment.

We studied sampling behaviour and mate choice in the fiddler crab Uca mjoebergi. Once a female selects a mate, she copulates in his burrow and remains there until releasing her aquatic larvae. U. mjoebergi occurs in habitats that are inundated only by the highest amplitude spring tides. Females can only release their larvae during these tides, and release before or after will result in complete failure of reproductive effort. Matings occur over a 5-day period near the end of neap tides. Our results suggest that within the mating period, females adjust their larval developmental rates by selecting specific burrows in which to incubate their clutches. We found that at the start of the mating period, females chose larger males as mates. Since male size was positively correlated to burrow width, females were selecting wide burrows and effectively incubating at lower temperatures. This would slow down the developmental rates of larvae. In contrast, females that mated late in the mating period selectively chose small males. By incubating in narrower, warmer burrows, these females may increase the developmental rates of larvae. We propose that females are selecting burrows to influence incubation rate and ensure timely release of their larvae. Female U. mjoebergi appear to adjust their preference for the direct benefits of mate choice to increase their reproductive success. Keywords Female mate choice . Temporal constraints . Burrow width . Development time . Fiddler crab