O efeito da salinidade no desenvolvimento larval do caranguejo - uçá, Ucides cordatus (Linnaeus, 1763) (Decapoda: Ocypodidae) no Norte do Brasil

O presente trabalho estudou o efeito da salinidade na sobrevivência e na duração do desenvolvimento larval do caranguejo-uçá, Ucides cordatus (do estuário do Rio Caeté, Norte do Brasil), até a fase de megalopa em sete tratamentos de salinidade (0, 5, 10, 15, 20, 25 e 30). A salinidade afetou significativamente a sobrevivência das larvas zoea, no entanto não afetou a duração do desenvolvimento larval (20,77 ± 1,56 dias). Nas salinidades 0, 5 e 10 houve total mortalidade das larvas zoea. Somente a partir da salinidade 15 observou-se um desenvolvimento completo até a fase de megalopa. A taxa de sobrevivência foi maior em salinidade 30 (72%) e menor em 15 (16%). A reduzida taxa de sobrevivência das larvas zoea de U. cordatus, em salinidades baixas, indica a necessidade de dispersão larval do estuário para as águas costeiras onde as condições de salinidade para o desenvolvimento larval são mais favoráveis. Caso contrário se não houvesse a dispersão, a reduzida salinidade das águas estuarinas no período chuvoso, causaria uma elevada mortalidade, afetando desta forma o recrutamento, a manutenção e o crescimento da população de U. cordatus nos manguezais.

Relative growth of Uca burgersi (Crustacea, Ocypodidae) from two mangroves in the southeastern Brazilian coast

The relative growth of the fiddler crab Uca burgersi Holthuis, 1967 was analyzed in two populations from different mangroves (Ubatumirim and Cavalo rivers) in the southeastern Brazilian coast, monthly sampled from May, 2001 to April, 2002. The population from a high productivity level mangrove reaches the sexual maturity in larger sizes than the population from a less productive site. This results can be attributed to the greater amount of nutrients found in the Cavalo than in Ubatumirim mangrove.

Crescimento somático do caranguejo-uçá Ucides cordatus (Crustacea, Brachyura, Ocypodidae) em laboratório

Em crustáceos, o aumento de tamanho ocorre imediatamente após a muda, quando o animal está com a carapaça mole. O crescimento de Ucides cordatus (Linnaeus, 1763) foi observado em laboratório, através da ocorrência de muda, incremento de muda e período de intermuda. O estudo foi realizado durante os meses de outubro/2000 a março/2002 e um total de 91 caranguejos (15 machos, 33 fêmeas e 43 juvenis) foi coletado no manguezal de Itacuruçá - Coroa Grande, Estado do Rio de Janeiro, Brasil. Os animais foram mantidos em dois tipos de tanques: os caranguejos adultos foram mantidos em tanques de 1000 l, durante 18 meses, enquanto os juvenis foram mantidos em tanques plásticos de 20 l de capacidade durante oito meses. Os animais foram mantidos em sistema aberto de circulação de água do mar e alimentados duas vezes por semana com folhas de Rhizophora mangle (L.) (Rhizophoraceae) e Laguncularia racemosa (Gaertn.) (Combretaceae). A largura da carapaça variou entre 50,1 a 70,0 mm nos machos, 40,2 a 80,0 mm entre as fêmeas e 1,1 a 40,1 mm entre os juvenis. A sobrevivência dos espécimes estudados foi de 46,7% entre os machos, 39,4% entre as fêmeas após dezoito meses e 67,4% entre os juvenis, após oito meses de observação. Os machos e as fêmeas realizaram três mudas durante o experimento, enquanto os juvenis realizaram até duas mudas. As mudas ocorreram entre agosto e abril, mostrando maior freqüência durante a primavera e o verão. O incremento na largura da carapaça diminuiu com o tamanho do indivíduo, com média de 2,21 ± 1,39% para os machos, 1,28 ± 0,84% para as fêmeas e 2,89 ± 2,13% para os juvenis. A relação entre o incremento percentual e a largura da carapaça pode ser expresso pela equação IM = -0.0707LC + 4.645 (r²= 0.40). O período de intermuda foi de 191 ± 140 dias entre os machos, 216 ± 76,2 dias entre as fêmeas e 54 ± 1,41 dia entre os juvenis. O incremento de muda foi estatisticamente significativo (p<0,05) quando comparados machos e fêmeas, e adultos e juvenis.

Gonad development in females of fiddler crab Uca rapax (Crustacea, Brachyura, Ocypodidae) using macro and microscopic techniques

The morphology of the ovaries in Uca rapax (Smith, 1870) was described based on macroscopic and microscopic analysis. Females were collected in Itamambuca mangrove, Ubatuba, state of São Paulo, Brazil. In the laboratory, 18 females had their ovaries removed and prepared for histology. Each gonad developmental stage was previously determined based on external and macroscopic morphology and afterwards each stage was microscopically described. The ovaries of U. rapax showed a pronounced macroscopic differentiation in size and coloration with the maturation of the gonad, with six ovarian developmental stages: immature, rudimentary, developing, developed, advanced and spent. During the vitellogenesis, the amount of oocytes in secondary stage increases in the ovary, resulting in a change in coloration of the gonad. Oogonias, primary oocytes, secondary oocytes and follicular cells were histologically described and measured. In female’s ovaries of U. rapax the modifications observed in the oocytes during the process of gonad maturation are similar to descriptions of gonads of other females of brachyuran crustaceans. The similarities are specially found in the morphological changes in the reproductive cells, and also in the presence and arrange of follicle cells during the process of ovary maturation. When external morphological characteristics of the gonads were compared to histological descriptions, it was possible to observe modifications that characterize the process in different developmental stages throughout the ovarian cycle and, consequently, the macroscopic classification of gonad stages agree with the modifications of the reproductive cells.

Estrutura populacional de Uca maracoani (Decapoda, Brachyura, Ocypodidae) no Baixio Mirim, Baía de Guaratuba, Paraná

Um estudo sobre a flutuação anual da abundância, composição de tamanho dos indivíduos, proporção de sexos, período reprodutivo e de recrutamento dos juvenis de uma população de Uca maracoani (Latreille, 1802-1803) foi realizado no Baixio Mirim, Baía de Guaratuba, Paraná (48º36'W e 25º52'S). Os animais foram coletados mensalmente, de fevereiro/2005 a janeiro/2006, durante as marés baixas de sizígia, e a sua largura da carapaça (LC) medida. A temperatura pontual do ar variou de 17 a 29ºC, a luminosidade de 8.740 a 151.300 lux, a salinidade de 8 a 25 e a temperatura do solo (superfície, 5 cm, 10 cm, 15 cm e 20 cm de profundidade) de 18,3 a 28,9ºC. Foram analisados 7.120 indivíduos, dos quais, 2.578 juvenis sexualmente indefinidos, 2.377 machos e 2.165 fêmeas. A abundância da população variou de 341 (abril) a 994 indivíduos (janeiro), mas a sua flutuação anual não esteve relacionada com a das variáveis abióticas estudadas. A proporção de sexos foi de 1:1 e a reprodução da espécie é do tipo contínuo, com dois picos de intensidade: um em abril e outro em novembro. O recrutamento de juvenis, também, é contínuo com dois períodos mais intensos no ano, um em julho e outro em dezembro-janeiro. A LC da população variou de 1,14 a 2,62 mm para juvenis sexualmente indefinidos, 2,58 a 17,83 mm para machos juvenis, 2,60 a 11,72 mm para fêmeas juvenis, 17,85 a 35,81 mm para machos maduros e 11,75 a 31,76 mm para fêmeas maduras. Os machos atingem tamanhos maiores do que as fêmeas.

Estructura del aparato reproductor masculino de Uca uruguayensis (Decapoda, Ocypodidae)

The structure of the male reproductive tract was described in Uca uruguayensis Nobili, 1901, by using histological methods, scanning electron microscopy techniques, and stereoscopic observations of fresh material. The aim of this work was to establish the functional changes associated with sexual maturation. The morphology of the first (G1) and second (G2) pair of gonopods was described. The male reproductive tract consists of paired organs: testes, and tubular and convoluted vas deferens (VD) ending with a terminal ampoule (TA).The (VD) is composed of three parts: anterior (AVD), medial (MVD) and posterior (PVD). The AVD and MVD are lined by a single layer of cubical cells. The PVD epithelial cells are columnar with elongated nuclei. The terminal ampoule comprises four interconnecting chambers and is externally surrounded by connective tissue. The study of testes and vas deferens at different times along the year suggests that U. uruguayensis has a single and continuous reproductive season from December to March. The TA has not been described in other brachyurans and this structure is novel to Brachyura.

Global literature of fiddler crabs, genus Uca (Decapoda, Ocypodidae): trends and future directions

Crabs of the genus Uca Leach, 1814 are characterized by having strong sexual dimorphism and a global distribution. Currently, 97 species have been described and analyzed under several aspects, including population ecology, physiology and ethology. However, there is no general summary of the information from the various literatures. The aim of this study is to perform a scientometric analysis of fiddler crab studies. For this we searched papers available in the Thomson ISI database that contained the words "Uca" OR "fiddler* crab*" between the years 1991 and 2007. For each paper, we researched and recorded the following characteristics: publication year; journal of publication; the first author's nationality; the country where the study was conducted; study type; species studied; and the work area. Our results indicated that there was no increase in the number of articles through the years considered. The Journal of Experimental Marine Biology and Ecology published most of the articles on Uca, indicating the importance of this group as a model for testing ecological hypotheses using experimental approaches. Our results also showed that United States had the highest number of authors and published studies on Uca, following the overall trend in dominance on scientific research. Furthermore, using models with three variables (per capita income, number of species of Uca and extent of coastal countries) we observed that, according to the Akaike Information Criterion, the per capita income was the most important correlate for the number of articles per country (both the author's country and country of study). Additionally, our results show that the species U. pugilator (distributed on the East Coast of the North American continent) was the species most singularly referenced in the papers considered. Moreover, our results indicate that most studies on Uca use a descriptive and local scale. The majority of papers in our literature search reflect studies in population biology, followed by behavioral and physiological characteristics.

Contribuição ao conhecimento dos crustaceos do Rio de Janeiro: Genero Uca (Decapoda: Ocypodidae)

This paper comprises: 1) A note on Systematists of fiddler crabs from the Bay of Rio de Janeiro, with its new species Uca olympioi, Uca salsisitus, and a new variety U. pugnax var. brasiliensis. 2) Female Uca characterization is easier and infuse certainness when we inquire her third maxillipod. 3) Redescriptions are made for type-locality animals at Rio de Janeiro and nearness. 4) Male characterization become possible through its maxillipod if we lose its quelipod. 5) A historical referendary originating into indigenous dialect « Guarany » about the name Uca and brasilian nicknames of the fiddler crabs. 6) A few Uca species from the Rio de Janeiro determinative keys asked after main distinctions among others species described over the world in paragraph « diagnose diferencial ». 7) A collected material catalogue and some mensurement tables.

Different pathways in the larval development of the crab Ucides cordatus (Decapoda, Ocypodidae) and their relation with high mortality rates by the end of massive larvicultures

One of the most limiting factors affecting the larval rearing of Ucides cordatus in the laboratory is a period of high mortality, which usually occurs late in the course of the larviculture during the metamorphosis from the zoeal to the megalopal phase. The objective of the present research was to analyze the post-embryonic development of U. cordatus on an individual basis and, in particular, to search for patterns linking disturbances in the molting process to the high larval death rates observed in massive larvicultures. A total of 50 larvae were individually reared from hatching to metamorphosis into the megalopal phase under controlled conditions, fed a combination of microalgae and rotifers. The survivorship rate was 70% until zoea V. The 35 surviving zoea V larvae followed two different pathways. Eleven underwent metamorphosis directly to megalopa, eighteen molted to zoea VI and six died as zoea V. In the last molting event, only two zoea VI larvae reached the megalopal stage, while the remaining sixteen died. In further observation under microscope, 13 of the dead zoea VI showed characteristics of the pre-molt stage and pereiopods disproportionably large in relation to the carapace. The observed pattern resembles the Molt Death Syndrome (MDS) described for other decapod species, in which larvae die in the late pre-molt phase of the molting cycle. We suggest that U. cordatus larvae develop disturbances in the molting process similar to the MDS described for other species and that these disturbances are related to a more complex pathway involving the emergence of larval stage zoea VI.

Growth of the mangrove crab Ucides cordatus (Brachyura, Ocypodidae)

During monthly samplings between September 1998 and August 2000. 3,660 specimens of Ucides cordatus (Linnaeus, 1763) (2054 males and 1606 females) were obtained and examined for size (CW carapace width) to determine growth-age equations for each sex. This species showed a slower growth, with a marked seasonal oscillation, in females as compared to males, suggesting application of the seasonal and nonseasonal von Bertalanffy growth model, respectively. CW&PROP; and k constant were closely similar for the two sexes (CW&PROP; (male) = 90.3 mm: CW&PROP; (female) = 88.6 mm; k(male) = 0.28; k(female) = 0.26). The age at sexual maturity was estimated to be around 3 years, while the age at legal size (CW = 60 mm) was 3.8 and 4.7 years for males and females, respectively. In the laboratory, juvenile stages did not show differences in growth rates under the same temperature and photoperiod conditions.

Fertilidade do caranguejo de mangue Ucides cordatus (Linnaeus) (Crustacea, Brachyura, Ocypodidae), em Iguape (São Paulo, Brasil)

A total of 58 Ucides cordatus (Linnaeus, 1763) ovigerous females in final embryonic stage were collected in mangrove forest at Iguape (São Paulo). Each female were kept in laboratory until the larvae hatching and had their carapace width (CW) measured with caliper (0.05 mm) and the larval number (LN) calculated by volumetric method. The hatching rates (HR) were calculated for each animal's size class (5 mm). The values of LN and CW obtained were subjected to regression analyses and the best fitting model was chosen by comparing the obtained determination coefficients (R²). The fertility varied from 71,200 to 220,800 larvae (147,169 ± 32,070 larvae), corresponding to 41.7 to 76.8 mm CW (63.7±7.9 mm), respectively. The relationship LNxCW was expressed by the equation LN = 284.1CW1.5º¹ (N = 58; R² = 0.74; p < 0.01), that showed a positive correlation between the variables. Most part of ovigerous females (89.7%) showed their hatching during the nightly period. A negative correlation between HR and CW was observed in these animals (p < 0.05), probably due to reduction of spermatophores in the seminal receptacle (multiparous females) or due to senility in the females with large size. The biological studies of U. cordatus are very important for practices adoption that preserve and make the rational use of this recourse in Brazilian's mangrove forests.

Embryology of the mangrove crab Ucides cordatus (Brachyura : Ocypodidae)

Ovigerous females of Ucides cordatus were collected at different mangrove areas in Iguape, SP, Brazil, and reared in the laboratory in order to describe each embryonic stage. Accounts of the biometry, internal morphology, and coloration of the eggs were taken. The embryonic development took 19 +/- 1d (27degreesC, 12:12 h) with eight well-defined stages. A salinity test on embryonic development was conducted, and a better result was obtained in a rearing at 15parts per thousand. Eggs are slightly ellipsoid through development and undergo an increase of 13.9% in diameter to 91.7% in volume. Cluster analysis revealed three different groups for diameter (Stages I-II, III-VI, and VII-VIII) and volume (Stages I-III, IV-V, and VI-VIII), supporting the classification of embryos into initial, intermediate, and final stages, which are currently used in studies on the reproductive biology of decapod crustaceans. In this species, the identification of the different embryonic stages can be achieved only if biometric data are combined with information on the internal morphology of embryos and coloration of the eggs.

Spermatozoal ultrastructure in three species of the genus Uca Leach, 1814 (Crustacea, Brachyura, Ocypodidae)

Morphological aspects of spermatozoa in marine animals have been used in recent decades as phylogenetic criteria (spermiotaxonomy). This paper presents ultrastructural descriptions of the spermatozoa from Uca maracoani, U. thayeri, and U. vocator. A small portion of the vas deferens of each species was examined under the transmission and scanning electron microscopy. The ultrastructural analysis showed that each spermatophore consists of a varying number of spermatozoa embedded in a dense fibrillar matrix surrounded by a membrane. The spermatozoa of U. maracoani, U. thayeri, and U. vocator are typical of brachyurans. The Voluminous acrosome is characterized by three different layers. The postero-lateral surface of the acrosome is cupped by the reduced cytoplasm, and the anterior surface is covered by the operculum. The perforatorium consists of coiled, helicoidal membranous tubules and is continuous with the cytoplasm. The nucleus is composed by uncondensed chromatin and presents several lateral arms distributed over the entire equatorial plane of the cell. The presence of the apical button is a well defined character among all species of the genus Uca, but in U. thayeri it was not observed. The accessory opercular ring can be found in the three studied species, but in distinct development degree-Two centrioles were detected in U. thayeri and U. vocator, but only one was found in U. maracoani. The presence of centrioles in the mature spermatozoa is the first account for the genus Uca upto-date. Considering the ultrastructure of the spermatozoa of U. maracoani, U. thayeri, and U. vocator, we suggest that these three species partially follow the morphological patterns previously described in other Thoracotremata brachyurans. The absence of the apical button in U. thayeri spermatozoa may represent an evolutionary novelty in the genus Uca. (C) 2007 Elsevier Ltd. All rights reserved.