Sérgio Luiz de Siqueira Bueno

Exotic species of freshwater decapod crustaceans in the state of São Paulo, Brazil: records and possible causes of their introduction

Based on recent surveys of the freshwater decapod fauna, distributional data of five exotic species of freshwater decapod crustaceans for the hydrographic basins of the state of São Paulo are presented, as part of a large initiative for a comprehensive survey of the state’s biodiversity (BIOTA-FAPESP Program). These species are the North American crayfish Procambarus clarkii (Girard) (Cambaridae), the crab Dilocarcinus pagei Stimpson (Trichodactylidae) from the Amazon and Paraguay/lower Paraná River Basins, and the palaemonid shrimps Macrobrachium rosenbergii (De Man), from the Indo-Pacific region, Macrobrachium amazonicum (Heller) and Macrobrachium jelskii (Miers), both from the Orinoco, Amazon and the Paraguay/lower Paraná River Basins. Possible modes by which their introduction might have occurred are commented upon and potential consequences are discussed.

Abbreviated Larval Development of the Freshwater Prawn, Macrobrachium Iheringi (Ortmann, 1897) (Decapoda, Palaemonidae), Reared in the Laboratory

The present paper describes and illustrates the early post-embryonic development of the freshwater prawn Macrobrachium iheringi (Ortmann, 1897) completely. This species presents an abbreviated larval development of the advanced type, consisting of two zoeal stages before metamorphosing to megalopa. Benthic behaviour is already displayed by the newly hatched zoea. Both zoeae and megalopa are lecithotrophic. Live or inert food particles are captured or collected only after the third moult (juvenile stage) when mouthparts and chelipeds become well developed and fully functional.

ESTIMATING THE POPULATION SIZE OF AEGLA FRANCA (DECAPODA: ANOMURA: AEGLIDAE) BY MARK-RECAPTURE TECHNIQUE FROM AN ISOLATED SECTION OF BARRO PRETO STREAM, COUNTY OF CLARAVAL, STATE OF MINAS GERAIS, SOUTHEASTERN BRAZIL

Abstract The Schumacher-Eschmeyer and the Schnabel estimators for closed population were employed to estimate the population size of Aegla franca from an isolated section (30 m long; area: 76.125 m2) of the Barro Preto stream (20°18′47″S; 47°16′37″W) in the summer and winter seasons of the year 2005. These methods involve mark-recapture technique with multiple sampling, and each season estimate was conducted for eight consecutive days. The study area was isolated with a 4 mm mesh net to prevent migration of aeglids into or out of the study area. Traps were randomly set overnight and inspected for captured aeglids in the following morning. Two marking techniques were employed separately: a mixture of silver purpurin powder and fast-drying glue gel (summer estimate) and cauterization by red-hot pin head (winter estimate). All unmarked individuals from each sampling event were sexed, had their carapace length measured and were then marked, and released back in midpoint of the isolated area of the stream along with previously marked (recaptured) specimens. The Schumacher-Eschmeyer estimator provided very close results between the summer (N = 212 and density = 2.8 ind./m2) and the winter (N = 218 and density = 2.9 ind./m2) estimates. The Schnabel estimate results were also very similar to that obtained by the Schumacher-Eschmeyer method for each corresponding season of the year. Regardless of the marking technique employed, the results obtained and field observations from each estimate indicate that none of the assumptions required by both methods were violated. After subtracting the percentage of immature specimens, the projected overall population size of mature Aegla franca for the whole extension of Barro Preto stream varied from approximately 33,200 in the summer and 29,500 adults in the winter (Schumacher-Eschmeyer estimator) for an estimated area of occupancy equivalent to 0.0125 km2.

Crustáceos decápodes de água doce com ocorrência no Vale do Ribeira de Iguape e rios costeiros adjacentes, São Paulo, Brasil

This paper contributes to the knowledge of the species richness and distribution of decapod crustaceans at the Ribeira de Iguape river basin, south of Sao Paulo State, Brazil. Seven protected areas (E.E. Jureia-Itatins, P.E. Ilha do Cardoso, P.E. Jacupiranga, P.E. Campina do Encantado, P.E. Carlos Botelho, P.E. Intervales and PETAR) were investigated, covering most of the Mata Atlântica remaining in the Ribeira de Iguape basin. Samples were taken during each season of the years 2000 and 2001 using two sampling methods (sieves and traps). Six species of palaemonid shrimps, three atyid shrimps, five aeglid anomuran crabs, and three trichodactylid and one grapsid crabs were collected.

REPRODUCTIVE BIOLOGY AND FUNCTIONAL MATURITY IN FEMALES OF AEGLA FRANCA (DECAPODA: ANOMURA: AEGLIDAE)

Abstract We describe the reproductive period, fecundity, and average size at the onset of functional maturity of female Aegla franca, the northernmost distributed aeglid species. The reproductive period is markedly seasonal and takes place from May (austral mid-autumn) to August (late winter). Ovigerous females appear quite abruptly in the population by May, and this condition is observed in all adult females sampled regardless of their size. The average size at the onset of functional maturity in females, at which 50% of the females sampled during the reproductive period were considered adults, was 12.75 mm CL. The smallest post-ovigerous female measured 12.06 mm carapace length (CL). Mean fecundity (±S.D.) from 41 females bearing early and intermediate eggs was 129.1 ± 32.2 and corresponded to a mean female CL of 14.11 mm. The elliptical-shaped eggs exhibited significant increase in size along the development stages. The third pair of pleopods bore higher number of eggs than the others. Compiled information regarding the reproductive period reported for aeglids revealed an increase in the breeding period length with latitude. The reproductive period tends to be shorter in localities under larger rainfall variation and smaller temperature variability than in sites with opposite climate conditions. Eggs tend to be fewer in number and larger in size towards lower latitudes. We present an hypothesis that stream water velocity might act as a major selective pressure during the early life history of fluvial aeglids with direct effect on the reproductive pattern.

Life Cycle and Population Structure of Aegla paulensis (Decapoda: Anomura: Aeglidae)

Abstract We describe growth, longevity, sex ratio, reproductive period, and recruitment of Aegla paulensis from Jaraguá State Park, São Paulo, Brazil (23°27′27.9″S; 46°45′32.3″W). The population was sampled monthly (September 2007 through August 2009) with the aid of traps. Over five thousand individuals were captured, sexed, measured (carapace length  =  CL) and inspected for reproductive traits (females only), and then released back to the sampling site. The pattern of the reproductive cycle was strongly seasonal (austral mid autumn through late winter), with a single recruitment pulse per year. The obtained von Bertalanffy growth equations were CL  =  21.25[1-e−0.041(t + 1.250)] and CL  =  16.52[1-e−0.049(t + 1.823)] for males and females, respectively. Males (mean CL ± SD  =  11.86 ± 2.79 mm) attain larger sizes than females (mean CL ± SD  =  10.84 ± 2.36 mm). Aegla paulensis reproduces twice during an estimated life span of 40.2 months for females and 33.9 months for males. Temporal variation of sex ratio showed a distinctive pattern characterized by a sequence of three distinct periods that repeated from one year to another, and which suggested that a behavioral component influence the proportion of sex in adult specimens sampled with traps during reproductive and non-reproductive periods.

Allometric Growth, Sexual Maturity, and Adult Male Chelae Dimorphism in Aegla Franca (Decapoda: Anomura: Aeglidae)

Abstract Allometric growth analysis on chelae dimensions vs. carapace length (CL) was employed to estimate average size at the onset of morphometric maturity (= puberty molt) and sexual dimorphism regarding the pair of chelae in Aegla franca. Males attain morphometric maturity (12.15 mm of CL) at a larger size than females (10.93 mm of CL). After the puberty molt, an additional change in the allometry level regarding chelae dimensions was detected in adult males (average CL = 19.00 mm). As a result, two sequential morphotype groups of adult males, herein designated as morphotype I and morphotype II, were recognized according to the state of development of the pair of claws. We postulate that the second change in this allometry level is related to functional maturity in this sex, based on the following observations: 1) temporal variation in the proportion between the two morphotype groups reveals that morphotype II individuals make up most of adult males in the population at the beginning of the seasonal reproductive period of the species, and 2) morphotype II males show a more robust pair of claws as compared to the predecessor morphotype, which might represent an advantageous trait in reproductive competition. Males and females of Aegla franca are heterochelous with handedness preponderance of the left chela. Claw size is a distinct dimorphic trait in this species, being significantly larger in male specimens.

Population size estimation of the exotic crayfish Procambarus clarkii (Girard) (Crustacea, Decapoda, Cambaridae) in the Alfredo Volpi City Park, São Paulo, Brazil

O tamanho de uma populacao adulta bem estabelecida da especie exotica de lagostim cambarideo Procambarus clarkii (Girard, 1852) em um lago artificial no Parque Municipal Alfredo Volpi, localizado na cidade de Sao Paulo, Brasil, foi estimada em quatro ocasioes distintas entre 1999 e 2001 atraves de tecnica de marcacao e recaptura e do metodo de Schumacher e Eschmeyer para estimativa da populacao. Os animais adultos foram marcados mediante a colocacao de um pequeno anel elastico na base de cada pedunculo ocular. O tamanho da populacao adulta variou de aproximadamente 269 e 273 (o ultimo obtido pelo modelo de Tanaka) no verao de 2000 e 2001, e entre 640 e 468 durante o periodo de inverno de 1999 e 2000 respectivamente.

Reproductive Biology in Females of Aegla Strinatii (Decapoda: Anomura: Aeglidae)

Abstract Females of Aegla strinatii (n  =  466) were sampled monthly (September 2003 to September 2005) by means of sieves and traps from Rio das Ostras (24°38′16.2″S; 48°24′05.2″W), at Jacupiranga State Park, South of São Paulo State, Brazil. The reproductive period was markedly seasonal (from May to September) encompassing the Austral late autumn through late winter. This is in accordance to the pattern of reproductive period variations in relation to the latitudinal climate variability verified in species of Aegla. The proportion of adult females exhibiting the ovigerous condition was higher in young/small specimens as compared to old/large ones, and suggests the occurrence of senescence in the latter group. Average size at the onset of functional maturity in females was estimated as 16.66 mm of carapace length (rostrum excluded). The number of eggs per ovigerous females ranged from 1 to 325. Eggs are slightly elliptical and average size varied according to embryonic stage. Mean (± standard deviation) carapace length of juveniles (n  =  118) was 1.50 ± 0.05mm (range: 1.40-1.65mm).

FLUCTUATIONS IN THE POPULATION SIZE OF THE HIGHLY ENDEMIC AEGLA PEROBAE (DECAPODA: ANOMURA: AEGLIDAE) CAUSED BY A DISTURBANCE EVENT

During a two-year field study (July 2008-June 2010), we observed a sharp decrease in the number of the freshwater decapods, Aegla perobae, sampled monthly at the type locality. A series of population size estimates by means of the Schumacher and Eschmeyer markrecapture method confirmed the decreasing trend of population size. Density dropped rapidly from 9.05 ind./m 2 in April 2009 to a situation in which a reliable population size estimate was no longer possible due to the difficulty in retrieving marked individuals by February 2010. Results from additional estimations in 2011 and 2012 indicated that a slow and steady recovery phase of the population size has initiated. We present the hypothesis that the observed decrease in population size is due to an extraordinarily high precipitation episode during the 2007 reproductive period, which likely suppressed recruitment of the cohort produced in that year, with impact on the size-class structure and reproductive output of the population in the years that followed.