Hábitat y historia de vida de Pachychelles laevidactylus (Crustacea, Anomura, Porcellanidae) en el intermareal rocoso de Mar del Plata, Argentina

RESUMEN Se analizó la estructura del hábitat, el crecimiento relativo, la heteroquelia, la estructura poblacional, la madurez morfométrica y la fecundidad de Pachycheles laevidactylus Ortmann, 1892, durante Abril, Mayo y Junio del 2005, en sustratos naturales de Mar del Plata, Argentina (38°02'S, 57°31'W). La cobertura algal, la exposición al oleaje y el tiempo de inmersión varió de manera significativa entre estratos y entre meses. La morfometría de las quelas no manifestó diferencias entre sexos. Las hembras mostraron el abdomen más grande que los machos. Si bien existió la heteroquelia, no se detectó lateralidad. Las tallas (ancho de caparazón) estuvieron comprendidas entre 0.67 mm a 9.3 mm para los machos, y entre 1.07 mm a 10.65 mm, para las hembras. La densidad de organismos varió entre meses y entre los estratos. La estructura poblacional, para el periodo de estudio, se explicó en función de la estructura del hábitat. La madurez morfométrica de las hembras fue registrada a los 4.38 mm de ancho de caparazón. El número de huevos se correlacionó positivamente con la talla de las hembras ovígeras con un mínimo de 2 huevos y un máximo de 160, pero esa relación dependió del avance en el desarrollo de los embriones.

Abstract Habitat structure, relative growth, the heterochely, population structure, morphometric maturity and fecundity of Pachycheles laevidactylus Ortmann, 1892 were analyzed during April, May and June 2005, in natural substrates of Mar del Plata, Argentina (38°02'S, 57°31'W). Algal cover, wave exposure and immersion time varied significantly between strata and between months. Chelae morphometry showed no differences between sexes. Females showed the greatest abdomen. While there was the heteroquelia, laterality not detected. The size (carapace width) ranged from 0.67 mm to 9.3 mm for males and from 1.07 mm to 10.65 mm, for females. The density of organisms varied among months and between strata. The population structure for the period of study explained depended on habitat structure. The morphometric maturity of females was recorded at the 4.38 mm of carapace width. The number of eggs was positively correlated with the size of the gravid females with a minimum of 2 eggs and a maximum of 160, but that relationship depended on progress in the development of embryos.

Hábitat y historia de vida de Pachychelles laevidactylus (Crustacea, Anomura, Porcellanidae) en el intermareal rocoso de Mar del Plata, Argentina / Habitat and life's story of Pachychelles laevidactylus (Crustacea, Anomura, Porcellanidae) in the rocky shore of Mar del Plata, Argentina

Se analizó la estructura del hábitat, el crecimiento relativo, la heteroquelia, la estructura poblacional, la madurez morfométrica y la fecundidad de Pachycheles laevidactylus Ortmann, 1892, durante Abril, Mayo y Junio del 2005, en sustratos naturales de Mar del Plata, Argentina (38°02'S, 57°31'W). La cobertura algal, la exposición al oleaje y el tiempo de inmersión varió de manera significativa entre estratos y entre meses. La morfometría de las quelas no manifestó diferencias entre sexos. Las hembras mostraron el abdomen más grande que los machos. Si bien existió la heteroquelia, no se detectó lateralidad. Las tallas (ancho de caparazón) estuvieron comprendidas entre 0.67 mm a 9.3 mm para los machos, y entre 1.07 mm a 10.65 mm, para las hembras. La densidad de organismos varió entre meses y entre los estratos. La estructura poblacional, para el periodo de estudio, se explicó en función de la estructura del hábitat. La madurez morfométrica de las hembras fue registrada a los 4.38 mm de ancho de caparazón. El número de huevos se correlacionó positivamente con la talla de las hembras ovígeras con un mínimo de 2 huevos y un máximo de 160, pero esa relación dependió del avance en el desarrollo de los embriones.(AU)

Habitat structure, relative growth, the heterochely, population structure, morphometric maturity and fecundity of Pachycheles laevidactylus Ortmann, 1892 were analyzed during April, May and June 2005, in natural substrates of Mar del Plata, Argentina (38°02'S, 57°31'W). Algal cover, wave exposure and immersion time varied significantly between strata and between months. Chelae morphometry showed no differences between sexes. Females showed the greatest abdomen. While there was the heteroquelia, laterality not detected. The size (carapace width) ranged from 0.67 mm to 9.3 mm for males and from 1.07 mm to 10.65 mm, for females. The density of organisms varied among months and between strata. The population structure for the period of study explained depended on habitat structure. The morphometric maturity of females was recorded at the 4.38 mm of carapace width. The number of eggs was positively correlated with the size of the gravid females with a minimum of 2 eggs and a maximum of 160, but that relationship depended on progress in the development of embryos.(AU)

Hábitat y historia de vida de Pachychelles laevidactylus (Crustacea, Anomura, Porcellanidae) en el intermareal rocoso de Mar del Plata, Argentina / Habitat and life's story of Pachychelles laevidactylus (Crustacea, Anomura, Porcellanidae) in the rocky shore of Mar del Plata, Argentina

Se analizó la estructura del hábitat, el crecimiento relativo, la heteroquelia, la estructura poblacional, la madurez morfométrica y la fecundidad de Pachycheles laevidactylus Ortmann, 1892, durante Abril, Mayo y Junio del 2005, en sustratos naturales de Mar del Plata, Argentina (38°02'S, 57°31'W). La cobertura algal, la exposición al oleaje y el tiempo de inmersión varió de manera significativa entre estratos y entre meses. La morfometría de las quelas no manifestó diferencias entre sexos. Las hembras mostraron el abdomen más grande que los machos. Si bien existió la heteroquelia, no se detectó lateralidad. Las tallas (ancho de caparazón) estuvieron comprendidas entre 0.67 mm a 9.3 mm para los machos, y entre 1.07 mm a 10.65 mm, para las hembras. La densidad de organismos varió entre meses y entre los estratos. La estructura poblacional, para el periodo de estudio, se explicó en función de la estructura del hábitat. La madurez morfométrica de las hembras fue registrada a los 4.38 mm de ancho de caparazón. El número de huevos se correlacionó positivamente con la talla de las hembras ovígeras con un mínimo de 2 huevos y un máximo de 160, pero esa relación dependió del avance en el desarrollo de los embriones.

Habitat structure, relative growth, the heterochely, population structure, morphometric maturity and fecundity of Pachycheles laevidactylus Ortmann, 1892 were analyzed during April, May and June 2005, in natural substrates of Mar del Plata, Argentina (38°02'S, 57°31'W). Algal cover, wave exposure and immersion time varied significantly between strata and between months. Chelae morphometry showed no differences between sexes. Females showed the greatest abdomen. While there was the heteroquelia, laterality not detected. The size (carapace width) ranged from 0.67 mm to 9.3 mm for males and from 1.07 mm to 10.65 mm, for females. The density of organisms varied among months and between strata. The population structure for the period of study explained depended on habitat structure. The morphometric maturity of females was recorded at the 4.38 mm of carapace width. The number of eggs was positively correlated with the size of the gravid females with a minimum of 2 eggs and a maximum of 160, but that relationship depended on progress in the development of embryos.

Historical background of the population biology of the swimming crab Arenaeus cribrarius (Crustacea: Portunidae) in the Ubatuba Coast, Southeast Brazil / Antecedentes históricos da biologia populacional do siri Arenaeus cribrarius (Crustacea: Portunidae) na costa de Ubatuba, Sudeste do Brasil

This study presents results obtained 25 years ago on the population structure, sex ratio, and handedness of Arenaeus cribrarius in Ubatuba, North coast of São Paulo State, Brazil. Sampling studies were conducted during two different periods (from November 1988 to October 1989, and from May 1991 to April 1993), one of them performed for pooled data, and other exclusively for Fortaleza Bay (monthly samples from November 1988 to October 1989). Males were larger (CW, average ± SD: 73.38 ± 15.78 mm) than females (68.45 ± 12.20 mm). The size between juvenile and adult stages has an overlap, for males (40-70mm CW) e fêmeas (45-75 mm CW). A prevalence of females was registered for pooled data (1:1.42; P < 0.01), but it was not recorded in Fortaleza Bay (1:1.25; P > 0.05). The sex ratio was close to 1:1 in the smaller size classes, with females dominating in the intermediate classes, and males in larger ones. In Fortaleza Bay, a female biased sex ratio was only noted in transect I (1:3.88; P < 0.05) and in the autumn (1:1.67; P < 0.05), with 73% of the specimens measured were right-handed.(AU)

Este estudo apresenta resultados obtidos há 25 anos sobre a estrutura populacional, razão sexual e heteroquelia de Arenaeus cribrarius, em Ubatuba, Litoral Norte do Estado de São Paulo, Brasil. As amostragens foram realizadas em dois períodos diferentes (novembro/1988 a outubro/1989, e maio/1991 a abril/1993), um delas realizada para os dois períodos agrupados, como também exclusivamente para a Enseada da Fortaleza. Os machos (LC, média ± DP: 73,38 ± 15,78 mm) apresentaram maior tamanho do que as fêmeas (68,45 ± 12,20 mm). O tamanho nos estágios juvenil e adulto se sobrepuseram, para machos (40-70mm LC) e fêmeas (45-75 mm LC). Houve prevalência de fêmeas para os dados agrupados (1:1,42; P < 0,01), o que não foi confirmado na Enseada da Fortaleza (1:1,25; P > 0,05). A razão sexual foi de 1:1 nas classes inicias de tamanho, com predomínio das fêmeas nas classes intermediárias, e dos machos naquelas maiores. Na Enseada da Fortaleza a razão sexual foi desbalanceada apenas no transecto I (1:3,88; P < 0,05) e no outono (1:1,67; P < 0,05), sendo 73% dos espécimes destros.(AU)

Historical background of the population biology of the swimming crab Arenaeus cribrarius (Crustacea: Portunidae) in the Ubatuba Coast, Southeast Brazil / Antecedentes históricos da biologia populacional do siri Arenaeus cribrarius (Crustacea: Portunidae) na costa de Ubatuba, Sudeste do Brasil

This study presents results obtained 25 years ago on the population structure, sex ratio, and handedness of Arenaeus cribrarius in Ubatuba, North coast of São Paulo State, Brazil. Sampling studies were conducted during two different periods (from November 1988 to October 1989, and from May 1991 to April 1993), one of them performed for pooled data, and other exclusively for Fortaleza Bay (monthly samples from November 1988 to October 1989). Males were larger (CW, average ± SD: 73.38 ± 15.78 mm) than females (68.45 ± 12.20 mm). The size between juvenile and adult stages has an overlap, for males (40-70mm CW) e fêmeas (45-75 mm CW). A prevalence of females was registered for pooled data (1:1.42; P 0.05). The sex ratio was close to 1:1 in the smaller size classes, with females dominating in the intermediate classes, and males in larger ones. In Fortaleza Bay, a female biased sex ratio was only noted in transect I (1:3.88; P < 0.05) and in the autumn (1:1.67; P < 0.05), with 73% of the specimens measured were right-handed.

Este estudo apresenta resultados obtidos há 25 anos sobre a estrutura populacional, razão sexual e heteroquelia de Arenaeus cribrarius, em Ubatuba, Litoral Norte do Estado de São Paulo, Brasil. As amostragens foram realizadas em dois períodos diferentes (novembro/1988 a outubro/1989, e maio/1991 a abril/1993), um delas realizada para os dois períodos agrupados, como também exclusivamente para a Enseada da Fortaleza. Os machos (LC, média ± DP: 73,38 ± 15,78 mm) apresentaram maior tamanho do que as fêmeas (68,45 ± 12,20 mm). O tamanho nos estágios juvenil e adulto se sobrepuseram, para machos (40-70mm LC) e fêmeas (45-75 mm LC). Houve prevalência de fêmeas para os dados agrupados (1:1,42; P 0,05). A razão sexual foi de 1:1 nas classes inicias de tamanho, com predomínio das fêmeas nas classes intermediárias, e dos machos naquelas maiores. Na Enseada da Fortaleza a razão sexual foi desbalanceada apenas no transecto I (1:3,88; P < 0,05) e no outono (1:1,67; P < 0,05), sendo 73% dos espécimes destros.

Relative growth of Acantholobulus schmitti (Rathbun, 1930) (Crustacea, Brachyura, Panopeidae) at Guaratuba Bay, southern Brazil / Crescimento relativo de Acantholobulus schmitti (Rathbun, 1930) (Crustacea, Brachyura, Panopeidae) na Baía de Guaratuba, sul do Brasil

A study on the relative growth of the crab Acantholobulus schmitti (Rathbun, 1930) (Decapoda, Brachyura, Panopeidae) was performed with allometric techniques. The species is associated with lanterns used for oyster farming at Guaratuba Bay, southern Brazil. Crabs were obtained from five lanterns from March through December 2009. The following morphological characteristics were measured: the carapace width (CW), the height and length of the major cheliped propodus (LPH and LPL), the width of the female abdomen at the base of the 4th somite (AW) and the length of the male gonopod (GL). A total of 1,004 individuals of A. schmitti were measured, of which 451 were males, 323 non-ovigerous females and 230 ovigerous females. The CW of the males varied from 1.87 to 11.86 mm, that of non-ovigerous females from 1.44 to 8.77 mm and that of ovigerous females from 4.09 to 11.12 mm. The plot of LPH against CW showed a mean inflection point at 3.67 mm CW for the males. This result indicated that male crabs are juvenile below this value and adult above it. For the females, the corresponding inflection point occurred at 3.36 mm CW in the plot of AW against CW. These results, CW x LPH and CW x AW, highlight the importance of chelae enlargement at the onset of maturation in males. Similarly, the widening of the abdomen in females is required to accommodate egg clutches during the reproductive period. Heterochely was recorded in both sexes. Right-handed crabs were more frequent than left-handed ones, with percentages of 75.8% in males and 82.7% in females. The population of A. schmitti from Guaratuba Bay becomes sexually mature at an earlier age than A. schmitti from the coast of São Paulo state. The lanterns used in oyster farming furnish a safe habitat in which these crabs can spend their entire benthic life.

Um estudo sobre o crescimento relativo do caranguejo Acantholobulus schmitti (Rathbun, 1930) (Decapoda Brachyura Panopeidae) foi realizado utilizando o método alométrico. A espécie está associada às lanternas de ostras na Baía de Guaratuba, no sul do Brasil. Os caranguejos foram obtidos de cinco lanternas de março a dezembro/2009. Foram obtidas as seguintes dimensões somáticas dos caranguejos: largura da carapaça (CW), altura e comprimento do própodo do maior quelípodo (LPH e LPL), largura do abdômen da fêmea na base do quarto somito (AW) e o comprimento de gonópodo dos machos (GL). Um total de 1.004 indivíduos de A. schmitti foi medido, destes 451 foram machos, 323 fêmeas e 230 fêmeas ovígeras. O CW dos machos variou de 1,87 a 11,86 mm, enquanto para fêmeas não-ovígeras de 1,44 a 8,77 mm e fêmeas ovígeras de 4,09 a 11, 12 mm. O gráfico de dispersão dos pontos empíricos entre CW e LPH mostrou um ponto de inflexão em 3,67 mm CW dentre os machos, indicando que abaixo deste valor, os caranguejos machos ainda são juvenis e acima dele, adultos. Para fêmeas, este ponto foi estabelecido em 3,36 mm CW no gráfico de dispersão entre CW e AW. Esses resultados das relações CW x LPH e CW x AW, destacam a importância do alargamento da quela no início da maturação dos machos, enquanto o alargamento do abdômen é uma demanda natural para as fêmeas, a fim de acomodar ovos no período reprodutivo. A heteroquelia ocorreu em ambos os sexos, sendo caranguejos destros mais frequentes do que os canhotos: 75,8% dentre os machos e 82,7% dentre as fêmeas. A população de A. schmitti da Baía de Guaratuba torna-se sexualmente madura mais cedo do que no litoral de São Paulo, e as lanternas de ostreicultura constituem um habitat seguro para estes caranguejos viverem plenamente a sua vida bentônica.

Relative growth of Acantholobulus schmitti (Rathbun, 1930) (Crustacea, Brachyura, Panopeidae) at Guaratuba Bay, southern Brazil / Crescimento relativo de Acantholobulus schmitti (Rathbun, 1930) (Crustacea, Brachyura, Panopeidae) na Baía de Guaratuba, sul do Brasil

A study on the relative growth of the crab Acantholobulus schmitti (Rathbun, 1930) (Decapoda, Brachyura, Panopeidae) was performed with allometric techniques. The species is associated with lanterns used for oyster farming at Guaratuba Bay, southern Brazil. Crabs were obtained from five lanterns from March through December 2009. The following morphological characteristics were measured: the carapace width (CW), the height and length of the major cheliped propodus (LPH and LPL), the width of the female abdomen at the base of the 4th somite (AW) and the length of the male gonopod (GL). A total of 1,004 individuals of A. schmitti were measured, of which 451 were males, 323 non-ovigerous females and 230 ovigerous females. The CW of the males varied from 1.87 to 11.86 mm, that of non-ovigerous females from 1.44 to 8.77 mm and that of ovigerous females from 4.09 to 11.12 mm. The plot of LPH against CW showed a mean inflection point at 3.67 mm CW for the males. This result indicated that male crabs are juvenile below this value and adult above it. For the females, the corresponding inflection point occurred at 3.36 mm CW in the plot of AW against CW. These results, CW x LPH and CW x AW, highlight the importance of chelae enlargement at the onset of maturation in males. Similarly, the widening of the abdomen in females is required to accommodate egg clutches during the reproductive period. Heterochely was recorded in both sexes. Right-handed crabs were more frequent than left-handed ones, with percentages of 75.8% in males and 82.7% in females. The population of A. schmitti from Guaratuba Bay becomes sexually mature at an earlier age than A. schmitti from the coast of São Paulo state. The lanterns used in oyster farming furnish a safe habitat in which these crabs can spend their entire benthic life.(AU)

Um estudo sobre o crescimento relativo do caranguejo Acantholobulus schmitti (Rathbun, 1930) (Decapoda Brachyura Panopeidae) foi realizado utilizando o método alométrico. A espécie está associada às lanternas de ostras na Baía de Guaratuba, no sul do Brasil. Os caranguejos foram obtidos de cinco lanternas de março a dezembro/2009. Foram obtidas as seguintes dimensões somáticas dos caranguejos: largura da carapaça (CW), altura e comprimento do própodo do maior quelípodo (LPH e LPL), largura do abdômen da fêmea na base do quarto somito (AW) e o comprimento de gonópodo dos machos (GL). Um total de 1.004 indivíduos de A. schmitti foi medido, destes 451 foram machos, 323 fêmeas e 230 fêmeas ovígeras. O CW dos machos variou de 1,87 a 11,86 mm, enquanto para fêmeas não-ovígeras de 1,44 a 8,77 mm e fêmeas ovígeras de 4,09 a 11, 12 mm. O gráfico de dispersão dos pontos empíricos entre CW e LPH mostrou um ponto de inflexão em 3,67 mm CW dentre os machos, indicando que abaixo deste valor, os caranguejos machos ainda são juvenis e acima dele, adultos. Para fêmeas, este ponto foi estabelecido em 3,36 mm CW no gráfico de dispersão entre CW e AW. Esses resultados das relações CW x LPH e CW x AW, destacam a importância do alargamento da quela no início da maturação dos machos, enquanto o alargamento do abdômen é uma demanda natural para as fêmeas, a fim de acomodar ovos no período reprodutivo. A heteroquelia ocorreu em ambos os sexos, sendo caranguejos destros mais frequentes do que os canhotos: 75,8% dentre os machos e 82,7% dentre as fêmeas. A população de A. schmitti da Baía de Guaratuba torna-se sexualmente madura mais cedo do que no litoral de São Paulo, e as lanternas de ostreicultura constituem um habitat seguro para estes caranguejos viverem plenamente a sua vida bentônica.(AU)