ABSTRACT In order to understand the role of lower order tributaries in the population structuring of the freshwater anomuran crab Aegla parana Schmitt, 1942, a study on the distribution of demographic categories was carried out along Negro River and in its tributary Totó River that belong to Upper Iguaçu Basin, southern Brazil. Two collection points were established along the main channel of Negro River, in a 7.00 km long stretch, and three points in the entire creek Totó River with 6.61 km long. The animals were captured with Surber net and baited traps and had the carapace length (CL) measured. A total 146 crabs were obtained from Negro River and 361 from Totó River, performing 507 analyzed aeglids. From the point 1 of Negro River, males measured 27.68 ± 12.68 mm CL and females 18.98 ± 5.88 mm CL; from point 2 of the same river, the values were 24.45 ± 13.70 mm CL and 27 ± 8.50 mm CL, respectively. There was a positive and direct relationship between the mean CL of the aeglids from Totó River and the distance of the collection points from its source. Males: point 1 (source of the creek): 7.90 ± 1.23 mm CL; point 2: 9.55 ± 3.06 mm CL; point 3: 9.91 ± 2.62 mm CL. Females: point 1 (source): 6.68 ± 1.70 mm CL; point 2: 9.01 ± 1.94 mm CL; point 3: 10.49 ± 2.57 mm CL. The sexually immature aeglids are distributed mainly in the lower order tributary (= Totó River), and the mature ones in the main channel of Negro River, indicating that this population perform ontogenetic migrations from tributary to the main river. The spatial partition can be explained under three aspects that are quite contrasting between Negro River and Totó River: 1. substrate architecture; 2. depth of the water column and 3. quality of available food.

Abstract The population structure and growth of two populations (Arraial and Capivari rivers) of Aegla schmitti was evaluated. The following parameters were determined: size, age structure, sex ratio, recruitment period, and sampling method selectivity (traps and handnet). There was variation between males and females. The carapace length size class distribution was unimodal in the Arraial River, and polymodal in the Capivari River. The sampling method influenced the proportion of demographic categories. The recruitment occurred mostly between October and December. The growth curves for the Arraial and Capivari rivers, respectively, were Ct= 26,50[1- e -0,004(t+53,36)] and Ct= 34,79[1- e -0,0024(t+122,34)] for males, and Ct= 23,07[1- e -0.0027(t+23,18)] and Ct= 25.52[1- e -0,0033(t+19,51)] for females. The maximum CL estimated for males and females were 26.50 and 23.07mm for the Arraial River, and 34.79 and 25.52mm for the Capivari River. Longevity was estimated in 2 years for females of both populations, and 2.5 and 3 years for males of the Arraial and Capivari rivers, respectively. The results allow for the characterization of the growth patterns of A. schmitti in two hydrographic basins, providing information for the species’ preservation and also demonstrating the selectivity of the different sampling methods used for aeglids.

Abstract The influence of salinity on the survival of the larvae of Leptuca leptodactyla (Rathbun, in Rankin, 1898) from zoea (Z) to megalopa (M) stage was analyzed in order to deduce the larval dispersal strategy of the species. Larvae were obtained from 10 ovigerous females captured in the mangrove of Guaratuba Bay, southern Brazil. Five salinity treatments were conducted from 0 to 35 PSU (S0, S5, S15, S25 and S35). The larvae were individually raised in plastic cell culture plates, totaling 120 experimental units per treatment, kept under natural photoperiod (12:12 h) and water constant temperature (26.3 ± 0.82°C), and fed with microalgae, rotifers and Artemia nauplii. While all larvae died at S0, S5 and S15, complete larval development until the M stage was only observed at S25 and S35. The highest survival rate was recorded at S35 (18 M from 120 newly-hatched Z, survivorship 15%) and the lowest at S25 (2 M, 1.66%). No significant difference in the total duration was observed between S25 (28.5 ± 0.70 days) and S35 (23.61 ± 3.05 days). The life cycle of L. leptodactyla is based on a larval exportation strategy as they need to perform ontogenetic migrations to the coastal area.

RESUMO O comprimento da carapaça (CL) no início da maturidade sexual morfológica (MSM) em Aegla paranaSchmitt, 1942foi estimado em uma população que ocorre na Sub-bacia do Rio Negro, Bacia do Alto Iguaçu, sul do Brasil. Os animais foram capturados com rede Surber e com armadilhas iscadas no Rio Negro e no seu afluente Rio Totó, em dezembro/2017, junho e julho/2018. Cada indivíduo teve o CL medido da ponta do rostro até a margem posterior da carapaça, com um paquímetro digital ou sob um microscópio digital. O comprimento do propódo do maior quelípodo (LMAP) dos machos e a largura do abdômen (AW) das fêmeas foram medidos para a análise de crescimento relativo. O CL de início da MSM foi estimado como o ponto de inflexão no gráfico de dispersão com o programa REGRANS. No Rio Negro, 107 machos (amplitude de variação do CL: 6,90-50,25 mm CL) e 95 fêmeas (10,37-39,36 mm CL) foram obtidos, enquanto no Rio Totó, 225 machos (4,92-25,65 mm CL) e 160 fêmeas (5,18-26,45 mm CL). MSM é atingido por machos com 23,15 mm CL e fêmeas com 17,85 mm CL. A menor fêmea ovígera mediu 19,00 mm CL. Aegla parana atinge o maior tamanho máximo e os machos atingem MSM com o maior valor de CL entre as espécies conhecidas do gênero.

ABSTRACT The carapace length (CL) at the onset of morphological sexual maturity (MSM) in Aegla paranaSchmitt, 1942was estimated in a population located at Negro River Sub-basin, Upper Iguaçu Basin, southern Brazil. The animals were captured with Surber net and with baited traps in Negro River and in its tributary Totó River, in December/2017, June and July/2018. Carapace length of each individual was measured from the tip of the rostrum to the posterior margin of the carapace, with a digital caliper or under a digital microscope. Length of the major cheliped propodus (LMAP) of males and width of the abdomen (LA) of females were measured for relative growth analysis. The CL at the onset of MSM was estimated as the inflection points on the scatter plots with the REGRANS program. In Negro River, 107 males (CL range 6.90- 50.25 mm) and 95 females (10.37-39.36 mm) were obtained, while in Toto River, 225 males (4.92-25.65 mm) and 160 females (5.18- 26.45 mm). MSM is attained by males at 23.15 mm CL and females at 17.85 mm CL. The smallest ovigerous female measured 19.00 mm CL. Aegla parana reaches the highest maximum size and males attain MSM with the highest CL value among the known species of the genus.

ABSTRACT A study on relative growth, sexual dimorphism and ontogenetic trajectory was carried out in a population of the aeglidAegla marginata coming from Barrinha River, Iguape River Basin, Tunas do Paraná, Paraná State, Brazil. The size the of morphological sexual maturity was estimated for males and females. The analysis of sexual dimorphism and ontogenetic trajectory were performed using geometric morphometric technique. Males reach maturity with 10.58 mm of carapace length (CL) and females with 10.38 mm CL. Sexual size dimorphism was only visible among adults, with males reaching larger sizes. This is probably related to the reproductive strategy of males. However, sexual shape dimorphism was found for both juveniles and adults: the posterior region of the carapace was wider in females. As the contrast of this feature was stronger in adults, it can be considered that large abdomen is advantageous for egg incubation. The allometric trajectories of juveniles presented similar directions, becoming divergent during the adult phase. The shape variation inA. marginataoccurred gradually throughout its development, with no abrupt transformation upon reaching sexual maturity. The reproductive adaptation is the main reason for the morphological variation within populations ofA. marginata.

Resumo Um estudo comparativo sobre o tamanho e a forma de Leptuca uruguayensis foi realizado entre as populações do Rio das Garças, Brasil (BP) e do Rio Solís Grande, Uruguai (UP). O tamanho do início da maturidade sexual, também foi estimado para UP. Foi analisado um total de 36 indivíduos para BP e 387 para UP. Para a análise do crescimento relativo, a largura da carapaça (LC) para ambos os sexos, comprimento do maior quelípodo (CMQ) dos machos e a largura do abdome (LA) das fêmeas foram mensurados. O tamanho da carapaça e do quelípodo foi maior em UP. A forma também diferiu, sendo a carapaça de UP mais ampla do que BP; rostro projetado para a frente e margem posterior posicionada mais anteriormente; o quelípodo de UP também foi mais amplo do que BP. Em UP, a LC variou de 4,28-19,5 mm (machos) e 2,53-16,3 mm (fêmeas); o CMQ variou de 1,79-31,60 mm (machos) e a LA de 0,80-8,53 mm (fêmeas). O início da maturidade sexual para UP foi estimado em 12,20 mm LC (machos) e 7,81 mm (fêmeas). Essas diferenças podem indicar que variáveis abióticas estão atuando distintamente nas duas localidades.

Abstract A comparative study on size and shape of Leptuca uruguayensis was carried out between populations from Garças River, Brazil (BP), and Solís Grande River, Uruguay (UP). The size of the onset of sexual maturity was also estimated for UP. A total of 36 crabs BP and 387 crabs UP were analyzed. In the relative growth analysis, carapace width (CW) for both sexes, major cheliped length (LMC) for males and abdomen width (AW) for females were measured. The centroid size of carapace (1.40±0.19 cm BP and 1.88±0.30 cm UP) and cheliped (1.16±0.22 cm BP and 1.58±0.45 cm UP) differed significantly (p<0.001). The shape also differed significantly (p<0.001), having UP wider carapace than BP, rostrum projected forward and posterior margin positioned more anteriorly; the cheliped of UP was also wider than BP. In UP, males' CW ranged 4.28-19.5 mm and females' 2.53-16.3 mm CW; males' LMC ranged 1.79-31.60 mm and females' AW, 0.80-8.53 mm. The onset of sexual maturity of UP was estimated in 12.20 mm CW for males and 7.81 mm for females. These differences are likely related to abiotic variables acting distinctly in the two localities.

ABSTRACT The aim of this study was to describe the behavior of newly-hatched juveniles and maternal care in Aegla schmitti. The experiment was conducted using seven ovigerous females with eggs at different stages of embryonic development and 12 eggs that had been placed in a separate aquarium. We observed asynchronous hatching in all females, with a mean of 66 hatched juveniles per female. The females also exhibited extended maternal care, allowing the juveniles to remain inside their abdominal chamber or on other parts of their body in the first few days after hatching. The juveniles that hatched in a separate aquarium fed on the remaining eggs, despite food being available. The incubation period and number of hatched eggs are highly variable between species with direct development, with no clear pattern being evident. However, asynchrony in hatching time is apparently common among freshwater anomurans, most likely due to the environmental conditions in which they live. Parental care is an important trait for crustaceans that live in osmotically unfavorable environments, such as freshwater, increasing the survival rate of juveniles.

Resumo Caranguejos braquiúros são um dos grupos mais diversificados de crustáceos, ocorrendo na maioria dos habitats costeiros. Devido à alta diversificação morfológica, procurou-se verificar a existência de padrões morfológicos relacionados ao habitat desses animais. Foram analisadas 17 espécies provenientes de manguezal, costão rochoso, praia de areia e ecossistema exclusivamente aquático marinho/estuarino. Em cada ambiente um total de 16 medidas lineares foi obtido para machos e 17 de fêmeas. Foram discriminados três grupos funcionais de espécies de caranguejos, baseado em seu habitat: 1. Substratos complexos, 2. Semiterrestre, 3. Exclusivamente aquático. As espécies pertencentes ao grupo Substratos complexos apresentaram pernas ambulatórias longas, bem como heteroquelia relacionada à vida em substratos irregulares. Espécies do grupo Semiterrestre apresentaram pernas ambulatórias de tamanhos distintos, o que lhes permite caminhar de maneira ágil sobre o ambiente terrestre graças à quarta perna ambulatória maior e aos pedúnculos oculares longos, importantes para a comunicação visual. Espécies do grupo Exclusivamente aquático apresentaram as maiores larguras de carapaça e pedúnculos oculares curtos. A presença de distintas linhagens de caranguejos nos ambientes analisados permitiu demonstrar uma clara convergência evolutiva, adaptando os caranguejos ao seu habitat e ambiente específico.

Abstract Brachyuran crabs are one of the most diverse taxa of crustaceans, occurring in almost all coastal habitats. Due to their high morphological diversification, the authors sought to ascertain the existence of morphological patterns related to the habitat of coastal brachyuran crabs. We analyzed 17 species from mangrove forests, rocky shores, sandy beaches and exclusively aquatic marine/estuarine ecosystems. A total of 16 linear measurements of males and 17 of females were obtained for each habitat. We were able to discriminate three functional groups of crab species, based on their habitat: 1. Complex Substrates, 2. Semiterrestrial, 3. Exclusively Aquatic. The species belonging to the Complex Substrates group had long ambulatory legs, as well as being heteroquely related to uneven terrain. Semiterrestrial species showed ambulatory legs of different sizes, allowing them to walk easily on the terrestrial terrain due to the long fourth ambulatory leg, and long eyestalks which are important for visual communication. Exclusively Aquatic species showed the largest carapace widths and the shortest eyestalks. The presence of different crab lineages in the environments analyzed allows us to demonstrate the clear evolutionary convergence, by which the crabs adapted to their specific habitat and environment.

RESUMO Um estudo sobre o dimorfismo sexual no caranguejo Hepatus pudibundus (Herbst, 1785) foi realizado utilizando morfometria geométrica. A carapaça de 28 machos e 30 fêmeas e o própodo dos quelípodos direito e esquerdo de 22 machos e 26 fêmeas foram analisados. Foram estabelecidos 13 marcos anatômicos bidimensionais na carapaça e 10 no própodo para ambos os sexos. Uma Análise Generalizada de Procrustes baseada na configuração dos marcos anatômicos foi utilizada para separar os componentes de tamanho e de forma. Um Teste-t de Student foi utilizada para determinar a significância estatística do dimorfismo sexual da carapaça e do própodo dos quelípodos. A variação na forma das estruturas foi avaliada através de uma Análise de Função Discriminante. Houve dimorfismo sexual na forma e no tamanho das estruturas analisadas. Machos mostraram dimensões menores do que fêmeas. A carapaça das fêmeas foi mais larga na região posterior do que em machos, indicando uma ampliação da área para acomodação da massa de ovos. O dedo fixo do própodo dos quelípodos das fêmeas está mais voltado para a parte posterior e pode facilitar a limpeza dos ovos fixados na câmara abdominal. Nossos resultados trazem novas informações sobre o desenvolvimento de caracteres sexuais secundários e as suas consequências sobre a forma da carapaça e o própodo dos quelípodos em machos e fêmeas de H. pudibundus.

ABSTRACT A study on sexual dimorphism in Hepatus pudibundus (Herbst, 1785) was performed using geometric morphometrics. The carapace of 28 males and 30 females and the left and right cheliped propodus of 22 males and 26 females were analyzed. Thirteen landmarks were established in the carapace and 10 in the cheliped propodus. A Generalized Procrustes Analysis based on landmark configurations was used to separate the components of size and shape. A Student t-test was used to determine the statistically significant sexual dimorphism of the carapace and the cheliped propodus. The variation in the shape of the structures was evaluated with a discriminant analysis. There was sexual dimorphism in the analyzed structures. Males were smaller than females. The carapace of females was larger in the posterior region than in males, indicating an expansion of the area for accommodation of the egg mass. The fixed finger of the cheliped propodus of females is more posteriorly arched that can be used to facilitate the cleaning of eggs laid in the abdominal chamber. Our results provide new information about the development of sexual secondary characters and their effects on the shape of the carapace and the cheliped propodus in males and females of H. pudibundus.

RESUMO O primeiro estágio juvenil do caranguejo chama-maré Minuca mordax foi descrito. Larvas zoea foram obtidas de fêmeas ovígeras e cultivadas em laboratório até atingir o primeiro estágio juvenil. O desenvolvimento de zoea I até o primeiro estágio juvenil teve duração de 35 dias após a eclosão. O cultivo foi mantido em um aquário com salinidade 20‰, sob fotoperíodo (claro: escuro/12:12) e temperatura (25°C) constante. Os juvenis foram dissecados e os apêndices desenhados e descritos. O primeiro estágio juvenil de M. mordax pode ser morfologicamente distinto do mesmo estágio de M. burgersi and L. cumulanta por apresentar antênula com endopodito bisegmentado (3-segmentos em M. burgersi, não segmentado em L. cumulanta), maxílula com endopodito não segmentado (2-segmentos em M. burgersi e L. cumulanta), e primeiro e segundo maxilípodo com endopodito 4-segmentado (respectivamente não segmentado e 5-segmentos em M. burgersi e L. cumulanta). Os seguintes caracteres são comuns a estas três espécies: pedúnculo da antênula bissegmentado; antênula com endopodito não segmentado; presença de estetascos na antênula; pedúnculo da antena trisegmentado; flagelo da antena 6-segmentado; mandíbula trisegmentada; maxila com coxal e basal endito bilobado; primeira, segunda e terceira maxila com exopodito bissegmentado e abdômen com seis somitos que são mais largos do que longos.

ABSTRACT The first stage of the fiddler crab Minuca mordax is described here. Zoea larvae obtained from four ovigerous female were reared in the laboratory until the development of the first crab stage. The development from zoea I to the first juvenile instar lasted 35 days after hatching. The first crab stage of Minuca mordax can be morphologically distinguished from those of Minuca burgersi and Leptuca cumulanta by a 2-segmented antennule endopod (3-segmented in M. burgersi, unsegmented in L. cumulanta), an unsegmented maxillule endopod (2-segmented in M. burgersi and L. cumulanta), and a 4-segmented first and second maxilliped endopod (respectively unsegmented and 5-segmented in M. burgersi and L. cumulanta). The three species have the following characters in common: segmented peduncle of antennule 2; endopod of antennule unsegmented; presence of aesthetascs on the antennule; peduncle of antenna 3-segmented; flagellum of antenna 6-segmented; mandible 3-segmented; maxilla with coxal and basal endite bilobed; first, second and third maxillae with exopod 2-segmented and abdomen with six somites that are wider than long.

A study on the temporal distribution, sex ratio, reproductive period, recruitment of juveniles and size composition of individuals of the fiddler crab Uca (Leptuca) uruguayensis was carried out in a population living in the Garças River mangrove, Guaratuba Bay, Paraná State, Brazil. Eight square samples of 0.25 m² (0.50 m side) were obtained on a monthly basis, from April/2011 to March/2012. The crabs were collected through the excavation of burrows and their carapace width (CW) was measured. Air and water temperatures varied from 19.0 to 29.5ºC and 17.0 to 27.0ºC, respectively, the salinity from 7 to 23 and the soil temperature from 19.0 to 29.2ºC. A total of 1,099 fiddler crabs were collected, being 529 males, 520 females (of these, 9 ovigerous) and 50 sexually undifferentiated individuals. The average density of the population ranged from 12 (June/11) to 71 ind.m-² (May/11), but its annual fluctuation was not correlated to abiotic variables. The sex ratio was 1:1 all year round and in all CW classes. Although in low abundance, ovigerous females were recorded in six months and juvenile crabs were present all year round, indicating a continuous reproduction and recruitment of the species. The CW of males ranged from 2.33 to 8.33 mm and that of females, from 2.52 to 7.79 mm: these data showed that this population is composed of smallest individuals among those studied

A study on the relative growth was carried out in a population of the fiddler crab Uca uruguayensis from the mangrove of Garças River, Guaratuba Bay, Paraná State, southern Brazil. The dimensions analyzed were the length of the major chela (LMC) of males and width of the abdomen (AW) of females, because they are related to reproductive activities of waving (males) and egg incubation (females). The cheliped handedness in males was also analyzed. The LMC was measured in 480 males, the AW in 566 females, and all crabs had the carapace width (CW) measured that was considered as the reference dimension for both sexes. The inflection point in the graphs between each the dimensions and CW was calculated with the aid of the software REGRANS. The CW ranged from 2.33 to 8.33 mm in males and from 1.65 to 7.79 mm in females. The relationship between CW and LMC showed an inflection point at 4.14 mm CW among males, and between CW and AW at 3.52 mm CW among females. The allometric growth was positive for both dimensions throughout the entire ontogeny of both sexes, before and after the puberty. The equations describing the relationship between CW and LMC in males were: logLMC = - 0.695960 + 1.72.logCW for juveniles and logLMC = - 1.212513 + 2.5.logCW for adults. In females, the equations were logAW = - 0.519071 + 1.02.logCW and logAW = - 0.902874 + 1.73.logCW, respectively for juveniles and adults. The population of U. uruguayensis from Guaratuba Bay is composed of the smallest crabs, and it also attains morphological sexual maturity at smallest CW. The frequency of occurrence of right and left handed males was statistically the same (1:1) as in most population of fiddler crabs.

This work aims to estimate the average size at the onset of morphological and physiological sexual maturity and the reproductive period of Callinectes danae. Specimens were captured from a shrimp fishing boat equipped with a trawl net from March 2009 to February 2010. After sorting, crabs were sexed, and the following morphometric dimensions were measured: carapace width (CW), length and height of the major (MAP and HMAP), and the minor cheliped propodus (MIP and HMIP) for both sexes, and the abdominal width for females (AW). The onset of morphological maturity was estimated with the REGRANS program, in which the inflection point is calculated. The size at the onset of physiological maturity was determined by logistic regressions fitted to the relationships between the percentages of juvenile and adult individuals of each CW. A total of 893 individuals were sampled. Of these individuals, 389 were males, 472 non-ovigerous females, and 32 ovigerous females. The CW ranged from 19.81 to 117.17 mm for males, 19.91 to 113.11 mm for non-ovigerous females, and 70.55 to 88.60 mm for ovigerous females. Morphological sexual maturity was attained at 86.47 mm CW (males) and 67.87 mm CW (females). The size at the onset of physiological maturity was calculated to be 86.50 mm CW (males) and 67.00 mm CW (females). Due to the closeness of these values, both techniques were deemed suitable for determination of the onset of sexual maturity in C. danae. This species reproduces throughout the year, but reproduction is more intense during the winter. Mature males are present throughout the year. Data from this investigation will help resource managers to develop strategies that will ensure a sustainable harvest of this important species of swimming crab in southern Brazil.

A predação oportunista dos peixes Astyanax fasciatus e Crenicichla sp. emalhados em rede de espera pelos eglídeos Aegla grisella e Aegla singularis foi observada em rios do Sul do Brasil. Estes eventos ocorreram em dois rios na Floresta Nacional de Passo Fundo, município de Mato Castelhano, RS e no município de Tanguará, SC. Em ambos os locais os peixes apresentavam um padrão de mutilação semelhante, com olhos e nadadeiras sendo consumidos primeiramente. No entanto, a predação de todo o corpo também foi registrada, provavelmente em decorrência do elevado número de eglídeos se alimentando de um mesmo indivíduo. Esse registro visa contribuir para o entendimento da dieta natural dos eglídeos em ambientes de águas continentais.

The opportunistic predation on the fishes Astyanax fasciatus and Crenicichla sp. entangled in gill net by the aeglid crabs Aegla grisella and Aegla singularis was observed in rivers of southern Brazil. These events occurred in two rivers located at the National Forest of Passo Fundo, in Mato Castelhano municipality, Rio Grande do Sul State and Tangará municipality, Santa Catarina State. In both places the fish showed similar wound pattern, with eyes and fins being consumed first. However, predation of the whole body was also recorded, probably due to the high number of aeglid crabs feeding on the same individual. This record intended to contribute for understanding the natural diet of these crabs in freshwater environments.

Este estudo teve por objetivo descrever a assembleia de crustáceos decápodos associados às cordas de cultivo de mexilhões em uma fazenda marinha localizada na Enseada da Armação do Itapocoroy, no Município de Penha, Santa Catarina, sul do Brasil. Os seguintes aspectos foram tratados: composição de espécies e peso total, sucessão de espécies e oscilação temporal da abundância, riqueza de espécies e diversidade (Shannon). O crescimento do mexilhão em (altura da concha e peso dos indivíduos) também, foram apresentados. Os decápodos foram amostrados de 15 cordas amostradas bimensalmente (três cordas a cada dois meses). Um total de 501 decápodos foram capturados, pertencentes a nove famílias, 15 gêneros e 21 espécies. A família dominante foi Porcellanidae, com sete espécies, seguida de Panopeidae (cinco) e de Pilumnidae (três), enquanto as demais foram representadas por uma espécie. A espécie mais abundante foi Pilumnus dasypodus (n = 244) que, junto com Synalpheus fritzmuelleri, Pachycheles laevidactylus, Pisidia brasiliensis, Menippe nodifrons, Pachycheles monilifer e Petrolisthes galathinus, somou 88% das ocorrências. A riqueza de espécies aumentou de três para 15 durante o experimento e a diversidade de espécies mostrou seu máximo no quinto mês seguido pelo nono, devido ao aumento da disponibilidade de refúgios no interior do substrato biológico composto por mexilhões vivos. O peso total dos decápodos representou apenas 3% do peso total das cordas de cultivo, devido ao seu tamanho reduzido. Isto indica que estes animais não podem ser considerados prejudiciais para o cultivou mexilhões. As cordas desempenham o papel de fornecer abrigo e fonte de alimento, já que a maioria destes decápodos passa todo o período bentônico do seu ciclo de vida neste biótopo.

This study aimed to describe the assemblage of decapod crustaceans associated with the mussel farming ropes located in the Armação do Itapocoroy Bay, in the municipality of Penha, Santa Catarina State, southern Brazil. The following aspects were assessed: species composition and total weight, succession of species and temporal oscillation of abundance, species richness and Shannon's diversity. The growth data (height and weight of the shells) of the biological substrate (mussels) are also presented. During the nine months of the experiment, associated decapods were collected from 15 ropes (three ropes every other month). A total of 501 decapods were collected that belonged to nine families, 15 genera and 21 species. The most dominant family was Porcellanidae, with seven species, followed by Panopeidae (five) and Pilumnidae (three), while the remaining families were represented by one species each. The most abundant species was Pilumnus dasypodus (n = 244) that together with Synalpheus fritzmuelleri, Pachycheles laevidactylus, Pisidia brasiliensis, Menippe nodifrons, Pachycheles monilifer and Petrolisthes galathinus summed up 88% of decapod. Species richness increased from three to 15 during the experiment and species diversity showed its maximum in the fifth and ninth month, due to increased availability of shelters within biological substrate composed of living mussels. The total weight of decapods represented only 3% of the total weight of the farming ropes, due to the smallness of them. This indicates that these animals cannot be considered harmful for the mussel farming. The ropes play a role of shelter and as food resource, since most of these decapods spend all their bentic life in this biotope.