Infaunal recruitment patterns in soft bottom habitats of the Patos Lagoon estuary, southern Brazil: influence of Chasmagnathus granulata (Brachyura, Grapsidae) disturbance

A comparative study of the infaunal recruitment patterns among disturbed surface sediment mounds around Chasmagnathus granulata Dana, 1851 burrows and undisturbed adjacent sediments was done in two intertidal soft bottom habitats (an upper and a lower mudflat zone) in an estuarine inlet of Patos Lagoon, southern Brazil. The most abundant infaunal organisms were recruits of the polychaete Laeonereis acuta Treadwell, 1923 and of the tanaid Kalliapseudes schubartii Mañé-Garzón, 1949. The densities of these species did not differ significantly between upper and lower mudflat habitats. These species showed lower densities around crab burrows than in adjacent areas, where differences in sediment characteristics were observed as well. The results indicate that C. granulata disturbances may play an important role in regulating the soft bottom benthic community by controlling infaunal recruitment in the estuarine intertidal mudflats of the Patos Lagoon.

Condition factor of Goniopsis cruentata (Crustacea, Brachyura, Grapsidae) from Mundaú/Manguaba estuarine complex, Alagoas, Brazil

The condition factor is a parameter which acts as a general indicator of the "well-being" of a species, and it can be obtained through the analysis of width vs. weight relationships. The present work aims to investigate size vs. weight relationship and the condition factor of the crab Goniopsis cruentata (Latreille, 1803). The study area was the Mundaú/Manguaba estuarine complex, Maceió, state of Alagoas, Northeast Brazil. Samplings were monthly accomplished from August 2007 to July 2008. A total of 626 individuals were analyzed, being 309 males and 317 females. Males were larger and heavier than females, what is expected in many brachyuran. The growth was positive allometric to both males (b = 3.42) and females (b = 3.30), not obeying the "cube law". The condition factor of female was higher than that of male crabs, probably due to the gonad weight of females. It also varied seasonally for both sexes, being higher in the autumn and winter in males, and in the autumn and spring in females, and related to the molt and period of spawning intensification.

Biology of Grapsus grapsus (LINNAEUS, 1758) (Brachyura, Grapsidae) in the Saint Peter and Saint Paul Archipelago, Equatorial Atlantic Ocean

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The first zoeal stage of two species of Grapsidae (Decapoda, Brachyura) and a key to such larvae from the Brazilian coast

First zoeal stages of the grapsinid Goniopsis cruentata (Latreille, 1803) and the sesarminid Aratus pisonii (H. Milne Edwards, 1837), are described and illustrated. Grapsinae zoeae can be distinguished from the other grapsid larvae by the absence of lateral spines on the carapace and the reduction of the antennal exopod to a small seta. A key to the first zoeal stage of the Brazilian coast Grapsidae is provided.

On the population biology of the mottled shore crab Pachygrapsus transversus (Gibbes, 1850) (Brachyura, Grapsidae) in a subtropical area

The mottled shore crab P. transversus is probably the most common brachyuran crab living in the marine rocky intertidal of southeastern Brazil. However, its biology is largely unknown. In this study, some aspects of the population biology of this species are investigated. Distribution of individuals in the intertidal range is heterogeneous. Sabellariid worm reefs and mytilid mussel beds can be considered as nursery grounds retaining most part of juveniles, while the rocky surface is mostly inhabited by adults, which find safety shelters in rock crevices. Annual size frequency distributions revealed clues of population stability and indicated that young individuals reach the adult habitat in a gradual process. Sex-ratio follows the 1:1 proportion in smaller size classes but is biased towards males in larger ones. Higher mortality in larger females is indicated as a possible cause of this pattern. Ovigerous ratio shows a remarkable seasonality in which highest percentages of ovigerous females occur during summer months, while recruitment of young is more intense from April to July, suggesting a very extensive larval development. Once established in the intertidal zone, young recruits will develop to mature individuals in late spring, when molting crabs become scarce and proportion of breeding females increases. Therefore, growth and reproduction are in a great part temporally separated, allowing an annual life cycle in which settlement, growth and breeding may take place within a I-yr period.

Allometry of the secondary sexual characters of the shore crab Pachygrapsus transversus (Gibbes, 1850) (Brachyura, Grapsidae)

The allometric growth of secondary sexual characters in Pachygrapsus transversus is investigated from the 2(nd) crab stage onward. Clear sexual dimorphism is restricted to abdominal morphology, but ANCOVA analyses showed that chelae become larger in males and the carapace becomes wider in females. Size at the puberty moult in both sexes was estimated using Somerton's computer techniques. Mature II analyses applied to bi-log gonopod length vs, carapace length relationships indicated a puberty moult at 5.0 mm in males.In females, Mature I analyses detected the overlapping growth phase lines in bi-log carapace length vs. abdomen width scatterplots. Fitting the logistic equation provided an estimate of 50% maturity at 5.5 mm. The regression lines separate young and resting individuals from the potentially reproductive females, but they do not separate young from adult crabs. Year-round monthly samples showed that the proportion of small adult-like females is higher during the breeding season. After breeding, females may moult to a young-like morphotype, as observed in controlled laboratory conditions. Moulting to a resting condition splits smaller mature females into different growth phase lines. Therefore, estimates of female size at sexual maturity by means of abdomen allometric growth analyses are inadequate in this species.

Zoeal morphology of Pachygrapsus transversus (Gibbes) (Decapoda, Grapsidae) reared in the laboratory

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Physiological maturity and relationships of growth and reproduction in the red mangrove crab Goniopsis cruentata (Latreille) (Brachyura, Grapsidae) on the coast of São Paulo, Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

ZOEAL MORPHOLOGY OF PACHYGRAPSUS-GRACILIS (SAUSSURE, 1858) (DECAPODA, GRAPSIDAE) REARED IN THE LABORATORY

The larval development of Pachygrapsus gracilis was studied in the laboratory under conditions of 25-degrees-C temperature and 20, 24, 28, 32 and 34 parts per thousand salinity. The objective of the study was to characterize the plankton phase of life of this species.

Reproductive patterns of Aratus pisonii (Decapoda: Grapsidae) from an estuarine area of São Paulo Northern Coast, Brazil

This paper describes the frequency of occurrence and reproductive patterns of the tree mangrove crab Aratus pisonii. Monthly samples were taken from January 1993 to June 1994 in an estuarine mangrove from Ubatuba region, Brazil. A total of 1 078 animals, 489 males and 589 females (131 ovigerous females) were collected. Carapace width ranged from 4.2 to 25.9 mm. A summer reproductive peak followed by a recruitment juvenile pulse was verified. Females were more abundant than males in the intermediate size classes. The sex-ratio in several months was biased towards females, suggesting a poligynous population and migration of females to mangrove fringes at the time of incubation and spawning.

External factors determining seasonal breeding in a subtropical population of the shore crab Pachygrapsus transversus (Gibbes, 1850) (Brachyura, Grapsidae)

Monthly samples of the shore crab Pachygrapsus transversus from two distinct annual periods showed that ovigerous females are present throughout the Year in the population. However, the relative ovigerous abundance of specimens among sexually mature changes from less than 10% during the winter months to almost 80% in summer. Linear correlations for each year revealed that both temperature and photoperiod were positively associated with relative abundance of ovigerous females. Multiple regression analyses suggested that photoperiod was the main factor affecting breeding in this species. Timing of observed reproductive pattern may enhance larval survival because of particular oceanographic conditions in the study region and favor early juvenile development due to certain species-specific growth features.

Redescription of megalopa and juvenile development of Pachygrapsus gracilis (Decapoda: Grapsidae) from the Amazon region, reared in the laboratory

ABSTRACT: This present study re-describes the megalopa stage and provides detailed morphological descriptions and main growth changes observed in stages I through VII of the juvenile instars of the dark shore crab Pachygrapsus gracilis (Saussure, 1858), from the Amazon region. The specimens in this study were reared in the laboratory and the megalopae were collected at Ajuruteua beach in northeastern Pará, Brazil. Previous studies had described the megalopa of P. gracilis from Mexican waters, as well as those of Pachygrapsus transversus (Gibbes, 1850) and Pachygrapsus marmoratus (Fabricius, 1787). A comparison between the Mexican and Amazonian populations of P. gracilis revealed significant morphological differences. The main difference is the presence of 3 elongated setae on the 5th pereiopods of individuals of the Amazonian population. The setal number and their arrangement in the appendages also differed. In P. gracilis, the male and female genital openings are observed from the juvenile instar III, whereas differentiation in male pleopods is observed only in juvenile instar V. In females, the pleopods undergo rapid differentiation during juvenile instar VI. These morphological comparisons and other observations on development are briefly compared and discussed with reports for other species.

IS CLEISTOSPERMY AND COENOSPERMY RELATED TO SPERM TRANSFER? A COMPARATIVE STUDY OF THE MALE REPRODUCTIVE SYSTEM OF PACHYGRAPSUS TRANSVERSUS AND PACHYGRAPSUS GRACILIS (BRACHYURA: GRAPSIDAE)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Biology of Grapsus grapsus (LINNAEUS, 1758) (Brachyura, Grapsidae) in the Saint Peter and Saint Paul Archipelago, Equatorial Atlantic Ocean

Eleven expeditions were undertaken to the Saint Peter and Saint Paul Archipelago to study the reproductive biology of Grapsus grapsus, providing additional information on limb mutilation and carapace colour. MATURE software was used to estimate morphological maturity, while gonadal analyses were conducted to estimate physiological maturity. The puberty moult took place at larger size in males (51.4 mm of carapace length) than in females (33.8 mm), while physiological maturity occurred at a similar size in males (38.4 mm) and in females (33.4 mm). Above 50 mm, the proportion of red males increased in the population, indicating that functional maturity is also related to colour pattern. Small habitat and high local population density contributed to the high rate of cannibalism. The low diversity of food items, absence of predators of large crabs and high geographic isolation are the determinants of unique behavioural and biological characteristics observed in the G. grapsus population.