Heat budgets, thermal structure and dissolved oxygen in Brazilian reservoirs

A comparison of the thermal regime and oxygen distribution patterns of some Brazilian reservoirs was made. A strong latitudinal dependence of surface temperature, annual mean and annual range was found. Except for Tucurui Reservoir, a reservoir of the Equatorial zone, the lowest surface temperature of the year in the other compared reservoirs was observed from June to August while the highest extended from October to February. The decreasing trend of annual mean temperatures and thermal ranges was due to the increasing seasonal variability of insolation with the latitude. A positive relationship between the increase on thermal surface-bottom differences and the depth of water column was found for reservoirs of similar latitudes. A long thermal stratification (around four months) was evidenced in the lacustrine zone of reservoirs with a residence time higher than 40 days. Low fluctuation (<2%) of the annual variability of heat contents was observed for the Tucurui Reservoir, while in das Garcas Reservoir a manmade lake located in the frontier between tropical and temperate regions, the annual coefficient of variation attained 13%. Concerning the heat budgets, the value for the Tucurui Reservoir was two times higher than in das Garcas Reservoir. Both the morphometric and climatological factors affected the heat contents of the two compared reservoirs. In deep eutrophic reservoirs, a significant reduction on the oxygen concentrations in the hypolimnetic zone was frequently observed. In some oligotrophic stratified reservoirs, a decrease on oxygen with depth occurred when the temperature of the hypolimnion was higher than 20 degrees C and caused a biochemical oxygen demand. In das Garcas Reservoir, the actual oxygen deficits ranged from 0.40 to 1.52 mg.O-2.cm(-2) and appear to be linked to oxygen consumption after the senescence of Microcystis aeruginosa populations in the spring. But, other factors such as the allochthonous loads of organic matter also had an important role on the oxygen balance of das Garcas Reservoir.

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.

Reproduction of the speckled swimming crab Arenaeus cribrarius (Brachyura : portunidae) on the Brazilian coast near 23 degrees 30 ' S

The reproductive biology of Arenaeus cribrarius from Ubatuba, São Paulo State, Brazil, was studied. Swimming crabs were sampled monthly for two years with otter trawls in two bays. A total of 941 males and 1,012 females were examined. Mating took place mainly in autumn involving postmolt females and intermolt males. At that time, gonad regression was verified in adult males, due to spermatophore transfer, and the molting of adult females. Ovigerous females or females with mature gonads were present year-round but more frequently captured during spring and summer. We found that 19, of all adult females were premolt, which indicated the occurrence of another mature instar and thus the absence of a well-defined terminal molt after puberty. Intermolt males were captured throughout the whole study period.

The first zoeal stage of the genus Cronius (Brachyura, Portunidae) from the Brazilian coast, hatched in a laboratory

This study describes the first zoeal stage of Cronius ruber and Cronius tumidulus. The zoeae can be distinguished using the setation of the cephalic appendages and the lateral process on the abdominal somite.

Relative growth and morphological sexual maturity of Chasmagnathus granulatus (Crustacea, Varunidae) from a mangrove area in southeastern Brazilian coast

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

Relative growth of Uca burgersi (Crustacea, Ocypodidae) from two mangroves in the southeastern Brazilian coast

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

Can seasonal differences influence food web structure on preserved habitats? Responses from two Brazilian streams

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

Subtropical Brazilian mangroves as a refuge of crab (Decapoda: Brachyura) diversity

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

Reproductive output of the spider crab Epialtus bituberculatus (H. Milne Edwards, 1834) (Crustacea, Decapoda, Brachyura) associated with beds of the alga Sargassum cymosum (C. Agardh, 1820) on the southeastern Brazilian coast

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Two new genera of Pteronemobiini crickets from the Brazilian Atlantic forest (Orthoptera, Grylloidea, Trigonidiidae, Nemobiinae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Bathymetric distribution of the shrimp Rimapenaeus constrictus (Stimpson, 1874) (Decapoda, Penaeidae) in two locations off the southeastern Brazilian coast

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

Predation of herps by spiders (Araneae) in the Brazilian Cerrado.

Two events of predation of herps by spiders in the Brazilian Cerrado are reported here. A lizard Micrablepharus atticolus (Sauria: Gymnophthalmidae) was found being preyed upon by Lycosa erythrognatha (Araneae: Lycosidae) and a frog Physalaemus cuvieri (Anura: Leiuperidae) was seen being preyed upon by Ancylometes sp. (Araneae: Ctenidae).

Relative growth and morphological sexual maturity of Uca Cumulanta (Crustacea : Decapoda : Ocypodidae) from a tropical Brazilian mangrove population

The relative growth of the fiddler crab Uca cumulanta was studied, primarily to determine the size at the onset of sexual maturity for a mangrove population in the estuary of the Patitiba River, Paraty, Rio de Janeiro state, Brazil. The evaluation of the morphological sexual maturity of U. cumulanta was performed using the allometric technique. The relationships that most precisely indicated the size at onset of sexual maturity were carapace length (CL) vs propodus length for males and CL vs abdomen width for females. Males and females are mature at 5.25 and 4.75 mm CL, respectively. The remarkable ontogenetic changes observed in the allometric growth of the male major cheliped and the female abdomen, indicate that growth of these structures is closely connected to the timing of sexual maturity. The relative size at onset maturity obtained for this species was 0.68 and this index was compared to that seen in other species in the genus.