70 resultados para terrestrial ecosystems


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Vegetable oils and their derivatives, like biodiesel, are used extensively throughout the world, thus posing an environmental risk when disposed. Toxicity testing using test organisms shows how these residues affect ecosystems. Toxicity tests using earthworms (Eisenia foetida. are widespread because they are a practical resource for analyzing terrestrial organisms. For phytotoxicological analysis, we used seeds of arugula (Eruca sativa and lettuce (Lactuca sativa. to analyze the germination of seeds in contaminated soil samples. The toxicological experiment was conducted with four different periods of biodegradation in soil: zero days, 60 days, 120 days and 180 days. The studied contaminants were soybean oil (new and used) and biodiesel (B100). An evaluation of the germination of both seeds showed an increased toxicity for all contaminants as the biodegradation occurred, biodiesel being the most toxic among the contaminants. on the other hand, for the tests using earthworms, the biodiesel was the only contaminant that proved to be toxic. Therefore, the higher toxicity of the sample containing these hydrocarbons over time can be attributed to the secondary compounds formed by microbial action. Thus, we conclude that the biodegradation in soil of the studied compounds requires longer periods for the sample toxicity to be decreased with the action of microorganisms.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The Neotropical pitviper genus Bothrops comprises about 40 species, which occur in all main ecosystems of cis-Andean South America. We explored the relationships of body size and form (tail length and stoutness) with macrohabitat use in 20 forms of Bothrops. Sen-ii-arboreal habits appeared only in forest forms. Semi-arboreals are significantly more slender and have longer tails than terrestrials; body size is not significantly different between terrestrials and semi-arboreals. Within Bothrops, independent contrasts for macrohabitat use were significantly correlated with contrasts of tail size (positively) and stoutness (negatively); thus, the more arboreal the species, the longer its tail and the more slender its body. Contrasts of adult body size seems to remain constant over the lower range of macrohabitat use, but to decrease in species of Bothrops which are more arboreal. Reconstructions of character states indicate that: (1) the ancestor of Bothrops was a small, stout, terrestrial species; (2) semi-arboreal habits appeared one to three times in the genus; (3) a decrease in stoutness and an increase in tail length occurred along with an increase in arboreality in some clades. Although macrohabitat use seems to be important in determining body form in Bothrops, our results also indicate that tail size, stoutness and body size may also be affected by selective agents other than macrohabitat use. The selective agents responsible for the shifts in macrohabitat use in Bothrops are still uncertain, although they may have included prey availability and/or predation pressure. The plasticity of macrohabitat use, morphology and body size described in this study may have been key features that facilitated the highly successful ecological diversification of Bothrops in South America.

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

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Psecas chapoda, a neotropical jumping spider strictly associated with the terrestrial bromeliad Bromelia balansae in cerrados and semi-deciduous forests in South America, effectively contributes to plant nutrition and growth. In this study, our goal was to investigate if spider density caused spatial variations in the strength of this spider-plant mutualism. We found a positive significant relationship between spider density and delta N-15 values for bromeliad leaves in different forest fragments. Open grassland Bromeliads were associated with spiders and had higher delta N-15 values compared to forest bromeliads. Although forest bromeliads had no association with spiders their total N concentrations were higher. These results suggest that bromeliad nutrition is likely more litter-based in forests and more spider-based in open grasslands. This study is one of the few to show nutrient provisioning and conditionality in a spider-plant system. (c) 2008 Elsevier Masson SAS. All rights reserved.

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

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

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Macroalgal species richness and diversity were analysed along a longitudinal profile in small and large scales during Spring, Fall and Winter, respectively in a small stream and a mid size river in the northwest region of São Paulo State, southeastern Brazil (20 degrees 23'-20 degrees 49'S, 49 degrees 26'-51 degrees 19'W). Longitudinal variation in species richness and diversity in small scale was strongly associated with incident light. Microhabitat distribution (from data taken by quadrat technique) revealed no significant correlations. Principal coordinates analysis (PCO) indicated no consistent groupings among sampling sites in distinct seasons (Spring, Fall and Winter). Longitudinal analysis in large scale revealed different patterns in the two seasons sampled (Spring and Winter), whereas species diversity presented a consistent tl end: high upstream, low in mid reaches and higher downstream. It was associated with type of substratum in Spring, rocky substrata presenting the highest values for species richness and diversity. Weak correlations were observed in Winter. Microhabitat distribution showed significant correlations between species abundance and the following variables: positive for rocky substrata and current velocity and negative for sandyclayish substratum and macrophyte-dominated substratum. PCO delineated only one consistent grouping formed by the two headwater sites. Small scale macroalgal distribution corroborated the longitudinal pattern predicted by the River Continuum Concept, whereas the large scale approach showed a distribution more associated with substratum type than to light availability. These results showed an opposite trend in relation to the expected distributional pattern. Longitudinal distribution in macroalgal community structure has yet to be better documented, particularly for tropical streams and no generalization is possible at this stage.

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The goal of this work was to establish comparisons among environmental degradation in different areas from Southern Spain (Gulf of Cadiz) and Brazil (Santos and Sao Vicente estuary), by using principal component analyses (PCA) to integrate sediment toxicity (amphipods mortality) and chemical-physical data (Zn, Cd, Pb; Cu, Ni, Co, V, PCBs, PAHs concentrations, OC and fines contents). The results of PCA extraction of Spanish data showed that Bay of Cadiz, CA-1 did not present contamination or degradation; CA-2 exhibited contamination by PCBs, however it was not related to the amphipods mortality. Ria of Huelva was the most impacted site, showing contamination caused principally by hydrocarbons, in HV-1 and HV-2, but heavy metals were also important contaminants at HV-1, HV-2 and HV-3. Algeciras Bay was considered as not degraded in GR-3 and -4, but in GR-3' high contamination by PAHs was found. In the Brazilian area, the most degraded sediments were found in the stations situated at the inner parts of the estuary (SSV-2, SSV-3, and SSV-4), followed by SSV-6, which is close to the Submarine Sewage Outfall of Santos - SSOS. Sediments from SSV-1 and SSV-5 did not present chemical contamination, organic contamination or significant amphipod mortality. The results, of this investigation showed that both countries present environmental degradation related to PAHs: in Spain, at Ria of Huelva and Gudarranque river's estuary areas; and in Brasil, in the internal portion of the Santos and Sao Vicente estuary. The same situation is found for heavy metals, since all of the identified metals are related to toxicity in the studied areas, with few exceptions (V for both Brazil and Spain, and Cd and Co for Brazilian areas). The contamination by PCBs is more serious for Santos and Sao Vicente estuary than for the investigated areas in Gulf of Cadiz, where such compound did not relate to the toxicity. (c) 2006 Elsevier Ltd. All rights reserved.

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Flowering phenology, breeding system and nectary structure of Corymborkis flava (Sw.) Kuntze were studied in a fragment of the Atlantic Forest in south-eastern Brazil. The flowering period extended from March (end of rainy season) to early June and seed dispersal occurred from June to September (dry season). Flowering peak occurred mainly in April, with up to 34 open flowers per plant being observed. The yellow, odourless and tubular flowers lasted similar to 7.8 days. The flowers present a perigonal nectary located in the basal lateral parts of the labellum; this is the first report on the nectary location and characterisation in the Tropidieae tribe. At the pre-anthesis stage, cells of both secretory parenchyma and epidermis of the nectary are filled with compound amyloplasts. However, starch grains were not observed in these tissues in senescent flowers, indicating that these starch grains are hydrolysed and used as source of sugars for nectar production. The nectar accumulates between the cuticle and the outer periclinal wall of the epidermal cells before. owing out into the nectar chamber. C. flava is a self-compatible species and spontaneous self-pollination does not occur because of hercogamy. The high pollinia removal (0.80) and insertion (0.82) per flower, as well as the high natural fruit-set indicate an efficient natural pollination system. The present study contributes for the knowledge of the diversity of reproductive strategies and nectary structures in Orchidaceae.

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