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Search Results: 1 - 10 of 673050 matches for " A. S;Arcifa "
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Early life stages of fish and the relationships with zooplankton in a tropical Brazilian reservoir: Lake Monte Alegre
MESCHIATTI, A. J.;ARCIFA, M. S.;
Brazilian Journal of Biology , 2002, DOI: 10.1590/S1519-69842002000100006
Abstract: for evaluating the trophic relationship between early life stages of fish and zooplankton in lake monte alegre, fish distribution and feeding habits have been studied in areas with and without macrophytes. in the first of these areas, 356 specimens belonging to 8 species, mostly juveniles, were caught by a sieve. another 35 specimens, belonging to 4 species, were caught by gill nets and seine in areas lacking macrophytes. their diets were composed of aquatic insects, microcrustaceans, rotifers, detritus, and other aquatic invertebrates. microcrustacean prey were mainly littoral or benthic dwellers, found in the highest proportion in specimens of 7-20 mm sl. most fish species have parental care, which could explain the absence of planktonic larvae. early life stages of fish do not exert a predation pressure on the lake zooplankton.
Early life stages of fish and the relationships with zooplankton in a tropical Brazilian reservoir: Lake Monte Alegre
MESCHIATTI A. J.,ARCIFA M. S.
Brazilian Journal of Biology , 2002,
Abstract: For evaluating the trophic relationship between early life stages of fish and zooplankton in Lake Monte Alegre, fish distribution and feeding habits have been studied in areas with and without macrophytes. In the first of these areas, 356 specimens belonging to 8 species, mostly juveniles, were caught by a sieve. Another 35 specimens, belonging to 4 species, were caught by gill nets and seine in areas lacking macrophytes. Their diets were composed of aquatic insects, microcrustaceans, rotifers, detritus, and other aquatic invertebrates. Microcrustacean prey were mainly littoral or benthic dwellers, found in the highest proportion in specimens of 7-20 mm SL. Most fish species have parental care, which could explain the absence of planktonic larvae. Early life stages of fish do not exert a predation pressure on the lake zooplankton.
Diel vertical migration of copepods in a Brazilian lake: a mechanism for decreasing risk of Chaoborus predation?
A., Perticarrari;Arcifa, M. S.;Rodrigues, R. A.;
Brazilian Journal of Biology , 2004, DOI: 10.1590/S1519-69842004000200015
Abstract: a comparison between two studies on diel vertical migration of two cyclopoid copepod species, in lake monte alegre, undertaken in 1985/86 and 1999, revealed a change in their migratory behavior. in summer, during a period of marked stratification with low dissolved oxygen near the bottom, the organisms avoided the deepest layers, and migration was nocturnal or undetectable, in both periods. on other occasions, with partial or total circulation in the lake, a weak twilight migration of copepodites and adults in 1985 was replaced by the reverse in 1999. differences were found among stages, with the weakest or undetectable migration being observed for nauplii. the migratory pattern change for copepodites and adults might be related with a recent predation pressure increase by chaoborus larvae on copepods, after the virtual disappearance of their main cladoceran prey.
Influence of seston quantity and quality on growth of tropical cladocerans
Fer?o-Filho, A. S;Arcifa, M. S.;Fileto, C.;
Brazilian Journal of Biology , 2005, DOI: 10.1590/S1519-69842005000100011
Abstract: the seston of the small, shallow, and tropical lake monte alegre was tested for quantity and quality for cladocerans by growth bioassays, which were carried out in spring (daphnia gessneri and moina micrura), summer (d. gessneri, m. micrura, ceriodaphnia cornuta, and simocephalus mixtus), and winter (d. gessneri and d. ambigua). cohorts of newborns originating from ovigerous females collected in the lake or from laboratory cultures were submitted, at a room temperature of 23oc to the following treatments: (1) the chlorophytes ankistrodesmus falcatus and/or scenedesmus spinosus; (2) lake seston; and (3) lake seston + chlorophytes. growth rate, clutch size, and fecundity were evaluated. seston alone was not the best food for promoting cladoceran growth. there were seasonal differences in food quantity and quality with spring and summer seston being better for growth than that of the winter. adding chlorophytes to the seston increased clutch size and fecundity for most species in summer and winter, but not in spring. energy limitation seems to be the most important factor influencing cladoceran growth in summer and especially in winter.
Feeding habits of Chaoboridae larvae in a tropical Brazilian reservoir
ARCIFA, M. S.;
Revista Brasileira de Biologia , 2000, DOI: 10.1590/S0034-71082000000400008
Abstract: the diet of the four larval instars of a chaoboridae species of lake monte alegre, was evaluated through the analysis of the crop content of individuals caught at night in the lake. peridinium and zooflagellates were the major components of the diet of instars i and ii, whereas microcrustaceans, especially the cladoceran bosmina, were most important for late instars. when the preferential prey decreased, in the course of the year, the diet was more diversified, increasing the ingestion of peridinium by instars iii and iv. there is a relationship between the mouth diameter of the larvae and the maximum width, height, or diameter of the ingested organisms.
Feeding habits of Chaoboridae larvae in a tropical Brazilian reservoir
ARCIFA M. S.
Revista Brasileira de Biologia , 2000,
Abstract: The diet of the four larval instars of a Chaoboridae species of Lake Monte Alegre, was evaluated through the analysis of the crop content of individuals caught at night in the lake. Peridinium and zooflagellates were the major components of the diet of instars I and II, whereas microcrustaceans, especially the cladoceran Bosmina, were most important for late instars. When the preferential prey decreased, in the course of the year, the diet was more diversified, increasing the ingestion of Peridinium by instars III and IV. There is a relationship between the mouth diameter of the larvae and the maximum width, height, or diameter of the ingested organisms.
Experiments on the influence of Chaoborus brasiliensis Theobald, 1901 (Diptera: Chaoboridae) on the diel vertical migration of microcrustaceans from Lake Monte Alegre, Brazil
Minto, WJ.;Arcifa, MS.;Perticarrari, A.;
Brazilian Journal of Biology , 2010, DOI: 10.1590/S1519-69842010000100006
Abstract: the aim of this work was to evaluate whether diel vertical migration of microcrustaceans from lake monte alegre is related to invertebrate predators, namely larvae of chaoborus brasiliensis. the hypothesis tested in the experiments was that the migratory behaviour of prey would depend on physical contact with chaoborus brasiliensis larvae or with kairomones released by them. two experiments were undertaken in the laboratory, with two treatments and three replicates each. experiments were carried out in acrylic cylinders 1.5 m high and 0.20 m in diameter. treatments in experiment i were: a) predator and kairomones present and b) predator and kairomones present, but predator isolated in net tube inside the cylinder, having no physical contact with prey. treatments in experiment ii were: a) predator and kairomones absent and b) the same as in experiment i. physical and chemical factors (temperature, dissolved oxygen, ph, electrical conductivity) and food (algae) did not influence vertical distribution of prey, as they were almost homogeneously distributed in the water column in both experiments; food concentrations were not limiting. adult copepods (tropocyclops prasinus meridionalis and thermocyclops decipiens) showed reverse migration in the treatment b of both experiments; the cladoceran daphnia gessneri migrated nocturnally in the treatment a of the experiment i; vertical migration was undetectable for copepodites, as well as for chaoborus larvae. the experiments indicated that daphnia responded to physical contact with chaoborus larvae but not to kairomones alone. adult copepods seemed to be more sensitive to kairomones.
Driving forces of the diel distribution of phytoplankton functional groups in a shallow tropical lake (Lake Monte Alegre, Southeast Brazil)
Rangel, LM.;Silva, LHS.;Arcifa, MS.;Perticarrari, A.;
Brazilian Journal of Biology , 2009, DOI: 10.1590/S1519-69842009000100009
Abstract: phytoplankton vertical and diel dynamics in a small shallow lake (lake monte alegre, ribeir?o preto, state of s?o paulo) were investigated in two climatological periods: july 2001 (cool-dry season) and march 2002 (warm-rainy season). monte alegre is a eutrophic reservoir, with a warm polymictic discontinuous circulation pattern. the lake was thermally stratified in both periods, although dissolved oxygen varied less in the cool-dry period. phytoplankton biomass was higher in the warm-rainy season and the vertical distribution was stratified in both seasons. flagellate groups (lm, y, w1 and w2) and functional groups typical of shallow eutrophic environments (j, x1 and sn) were important throughout the study period. the lake's thermal pattern strongly influenced the vertical distribution of the phytoplankton community in both periods. biomass, functional groups and size classes of phytoplankton also were determined by the presence of more efficient herbivores in the lake, especially during the cool-dry period when phytoplankton biomass decreased.
Water mite predation on zooplankton of a tropical lake
CASSANO, C. R.;CASTILHO-NOLL, M. S. M;ARCIFA, M. S.;
Brazilian Journal of Biology , 2002, DOI: 10.1590/S1519-69842002000400002
Abstract: water mite (krendowskia sp.) predation on zooplanktonic species from lake monte alegre (s?o paulo state, brazil) was tested in laboratory experiments. one cladoceran, daphnia gessneri, two copepods, tropocyclops prasinus and thermocyclops decipiens, and chaoborus larvae iii and iv were supplied as prey to adult mites. the cladoceran ceriodaphnia cornuta was used in the experiment with mite nymphs. only d.gessneri was preyed on by mites, at an average rate of 7 ind./mite/day, at 23-24oc. although chaoborus was not eaten by the predator in the experiment, in direct observations older larvae were seen to be seized by several mites, both predators and prey sinking to the bottom of the vessel. adult daphnia was grabbed by its dorsal side, swimming together with the mite. there was an increase in predatory activity two hours after sunset.
Water mite predation on zooplankton of a tropical lake
CASSANO C. R.,CASTILHO-NOLL M. S. M,ARCIFA M. S.
Brazilian Journal of Biology , 2002,
Abstract: Water mite (Krendowskia sp.) predation on zooplanktonic species from Lake Monte Alegre (S o Paulo State, Brazil) was tested in laboratory experiments. One cladoceran, Daphnia gessneri, two copepods, Tropocyclops prasinus and Thermocyclops decipiens, and Chaoborus larvae III and IV were supplied as prey to adult mites. The cladoceran Ceriodaphnia cornuta was used in the experiment with mite nymphs. Only D.gessneri was preyed on by mites, at an average rate of 7 ind./mite/day, at 23-24oC. Although Chaoborus was not eaten by the predator in the experiment, in direct observations older larvae were seen to be seized by several mites, both predators and prey sinking to the bottom of the vessel. Adult Daphnia was grabbed by its dorsal side, swimming together with the mite. There was an increase in predatory activity two hours after sunset.
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