Population dynamics of the freshwater crab Dilocarcinus pagei in tropical waters in southeastern Brazil

Populations of Pseudevadne tergestina were studied in Guanabara Bay, southeastern Brazil, to assess temporal variations in density and population dynamics. Data on temperature, salinity and zooplankton samples were taken from the superficial water of a fixed station, every 3 - 4 days, from February 2 through August 1, 2000. The highest abundance of this species was observed in March, when densities varied widely, from 20 to 600 ind. m-3. Population parameters were calculated, such as birth rate (from 0.25 to 0.90 ind.-1.day-1), growth rate (from -1.30 to 2.09 day-1 ) and death rate ( from -1.6 to 1.9 day-1 ) Start of population could be attributed to the increase of temperature and to the hatching of resting eggs. The population collapsed in fall-winter, as result from the combined effects of different factors: decrease of water temperature (from 27ºC to 21ºC) influencing egg development time (from 2.27 to 3.28 days); predation pressure by chaetognaths (Max. 100 ind. m-3 ) and switch of population from parthenogenic to sexual reproduction. Horizontal transport of water by tidal currents contributed partially to the reduction of population density.

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The relative growth and sexual maturity of the freshwater crab Dilocarcinus pagei (Brachyura, Trichodactylidae) in the northwestern region of the state of São Paulo

Iheringia Série Zoologia ◽

10.1590/s0073-47212013000300004 ◽

2013 ◽

Vol 103 (3) ◽

pp. 232-239 ◽

Cited By ~ 7

Author(s):

Daphine R. Herrera ◽

Thiago M. Davanso ◽

Rogerio C. Costa ◽

Fabiano G. Taddei

Keyword(s):

Sexual Maturity ◽

Sao Paulo ◽

Minimum Size ◽

São Paulo ◽

Freshwater Crab ◽

Relative Growth ◽

Stage Of Development ◽

Gonadal Maturity ◽

Size At Sexual Maturity ◽

Dilocarcinus Pagei

The aim of the present study was to determine the size at sexual maturity in the freshwater crab Dilocarcinus pagei Stimpson, 1861, from a population located in Mendonça, state of São Paulo, Brazil. The crabs were sampled monthly (July 2005 to June 2007), at Barra Mansa reservoir. The specimens were captured manually or in sieves passed through the aquatic vegetation. The crabs were captured and separated by sex based on morphology of the pleon and on the number of pleopods. The following dimensions were measured: carapace width (CW); carapace length (CL); propodus length (PL); and abdomen width (AW). The morphological analysis of the gonads was used to identify and categorize individuals according to their stage of development. The morphological maturity was estimated based on the analysis of relative growth based on the allometric equation y = ax b. The gonadal maturity was based on the morphology of the gonads by the method CW50 which indicates the size at which 50% of the individuals in the population showed gonads morphologically mature to reproduction. The biometric relationships that best demonstrated the different patterns of growth for the juvenile and adult stages were CW vs. PL for males and CW vs. AW for females (p<0.001). Based on these relationships, the estimated value to morphological sexual maturity was 21.5 mm (CW) in males and 19.7 mm (CW) in females. The determination of the size at sexual maturity and the adjustment of the data based on the logistic curve (CW50) resulted in a size of 38.2 mm for males and 39.4 mm for females (CW). Based on the data obtained for sexual maturity for D. pagei, we can estimate a minimum size for capture of 40 mm (CW). This minimum size allows at least half of the population to reproduce and retains the juveniles and a portion of the adults in the population.

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Population dynamics and secondary production of a key benthic tanaidacean, Monokalliapseudes schubarti (Mañé-Garzón, 1949) (Tanaidacea, Kalliapseudidae), from a tropical coastal lagoon in southeastern Brazil

Crustaceana ◽

10.1163/15685403-00003704 ◽

2017 ◽

Vol 90 (11-12) ◽

pp. 1483-1499

Author(s):

Simone Pennafirme ◽

Abilio Soares-Gomes

Keyword(s):

Growth Rate ◽

Population Dynamics ◽

Growth Curve ◽

Coastal Lagoon ◽

Secondary Production ◽

Growth Parameters ◽

Southeastern Brazil ◽

Tropical Coastal Lagoon ◽

Trade Offs ◽

Tropical Areas

Estimates of population dynamics and secondary production are important to understand the role of species in ecosystems and the mechanisms that drive life-history trade-offs, contributing to system preservation and monitoring. Population dynamics (growth rate, instantaneous mortality rates and longevity) and secondary production (biomass, production and P/B ratio) of the key marine benthic species Monokalliapseudes schubarti (Mañé-Garzón, 1949) were investigated monthly in a tropical coastal lagoon over 18 months and compared with data from other subtropical and temperate populations. A growth curve was estimated by fitting the Von Bertalanffy growth model. M. schubarti showed latitudinal variation in growth parameters. In tropical areas, M. schubarti generated consecutive cohorts and the growth curve parameters were: , , . A smaller asymptotic length was found for tropical and subtropical areas compared with data from temperate areas, and a lower growth rate was found at the tropical site. The annual mortality rate for the finite population was 0.999 year−1. Longevity, estimated at 10 months, was lower at the tropical site. The secondary production rate of M. schubarti at the tropical coastal lagoon was 10.60 g AFDW m−2 year−1, with a P/B ratio = 5.44. Brief longevity, a high P/B ratio, and high mortality may indicate M. schubarti as an opportunistic species in tropical areas.

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Daily Rhythm of Feeding Activity of the Freshwater Crab Dilocarcinus Pagei Pagei in the Rio Pilcomayo National Park, Formosa, Argentina

Modern Approaches to the Study of Crustacea ◽

10.1007/978-1-4615-0761-1_27 ◽

2002 ◽

pp. 171-178 ◽

Cited By ~ 7

Author(s):

Verónica Williner ◽

Pablo A. Collins

Keyword(s):

National Park ◽

Feeding Activity ◽

Daily Rhythm ◽

Freshwater Crab ◽

Dilocarcinus Pagei

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Small mammal populations of an agroecosystem in the Atlantic Forest domain, southeastern Brazil

Brazilian Journal of Biology ◽

10.1590/s1519-69842007000100025 ◽

2007 ◽

Vol 67 (1) ◽

pp. 179-186 ◽

Cited By ~ 18

Author(s):

PS. D’Andrea ◽

R. Gentile ◽

LS. Maroja ◽

FA. Fernandes ◽

R. Coura ◽

...

Keyword(s):

Population Dynamics ◽

Species Richness ◽

Atlantic Forest ◽

Small Mammal ◽

Abundant Species ◽

Common Species ◽

Southeastern Brazil ◽

Small Mammal Community ◽

Population Sizes ◽

Didelphis Aurita

This study reports 2 years of the population dynamics and reproduction of a small mammal community using the removal method. The study was conducted in a rural area of the Atlantic Forest, in Sumidouro, Rio de Janeiro State, Brazil. The population sizes, age structure and reproduction were studied for the four most common species in the study area. The overall diversity was 1.67 and ranged between 0.8 to 1.67. The species richness was 13 considering the whole study. The most abundant species were the rodents Nectomys squamipes (n = 133), Akodon cursor (n = 74), Oligoryzomys nigripes (n = 25) and the marsupials Didelphis aurita (n = 58) and Philander frenatus (n = 50). Seven other rodents were captured once: Necromys lasiurus, Akodon montensis, Sooretamys angouya, Oecomys catherine, Oxymycterus judex, Euryzygomatomys spinosus and Trinomys iheringi. There were higher peaks for diversity and species richness during the winter (dry) months, probably due to higher food availability. The marsupials had a seasonal reproduction with highest population sizes at the end of the rainy seasons. Nectomys squamipes reproduced mostly during rainy periods. Akodon cursor reproduced predominantly in the winter with the highest population peaks occurring during this season. The analysis of the population dynamics of the rodent species indicated that no species behaved as an agricultural pest, probably due to the heterogeneous landscape of high rotativity of vegetable cultivation. Rodent populations were more susceptible to the removal procedure than marsupial ones.

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