57 resultados para important memories
em Publishing Network for Geoscientific
Resumo:
The vegetation pattern of siliceous boulder snow beds (Dicranoweision crispulae all. nov. prov.) of Svalbard was investigated by using transect studies in several places on Spitsbergen. Dicranoweisia crispula is the best diagnostic species. It is found throughout the whole snow bed, is a good differential species against Racomitrium lanuginosum communities above the snow bed, and does not occur on basic rocks. Three Andreaea spp. are also among the most important members of these communities. They are all acidophilous, but with different pH preferences. Eight weakly acidophilous species lacking both on basic and on gneissic/granitic rocks, are reported from Svalbard. Half of these are characteristic species of Dicranoweision crispulae on Svalbard.
Resumo:
We tested the effect of near-future CO2 levels (= 490, 570, 700, and 960 µatm CO2) on the olfactory responses and activity levels of juvenile coral trout, Plectropomus leopardus, a piscivorous reef fish that is also one of the most important fisheries species on the Great Barrier Reef, Australia. Juvenile coral trout reared for 4 weeks at 570 µatm CO2 exhibited similar sensory responses and behaviors to juveniles reared at 490 µatm CO2 (control). In contrast, juveniles reared at 700 and 960 µatm CO2 exhibited dramatically altered sensory function and behaviors. At these higher CO2 concentrations, juveniles became attracted to the odor of potential predators, as has been observed in other reef fishes. They were more active, spent less time in shelter, ventured further from shelter, and were bolder than fish reared at 490 or 570 µatm CO2. These results demonstrate that behavioral impairment of coral trout is unlikely if pCO2 remains below 600 µatm; however, at higher levels, there are significant impacts on juvenile performance that are likely to affect survival and energy budgets, with consequences for predator-prey interactions and commercial fisheries.
Resumo:
A future business-as-usual scenario (A1FI) was tested on two bloom-forming cyanobacteria of the Baltic Proper, Nodularia spumigena and Aphanizomenon sp., growing separately and together. The projected scenario was tested in two laboratory experiments where (a) interactive effects of increased temperature and decreased salinity and (b) interactive effects of increased temperature and elevated levels of pCO2 were tested. Increased temperature, from 12 to 16 °C, had a positive effect on the biovolume and photosynthetic activity (F v/F m) of both species. Compared when growing separately, the biovolume of each species was lower when grown together. Decreased salinity, from 7 to 4, and elevated levels of pCO2, from 380 to 960 ppm, had no effect on the biovolume, but on F v/F m of N. spumigena with higher F v/F m in salinity 7. Our results suggest that the projected A1FI scenario might be beneficial for the two species dominating the extensive summer blooms in the Baltic Proper. However, our results further stress the importance of studying interactions between species.
Resumo:
The Paleogene sequences from three sites in the Caribbean were examined for radiolarians. In general, samples are highly lithified, requiring lengthy and repetitive cleaning procedures, and the assemblages are usually fragmented and/or partially dissolved. Both abundances and preservation of the assemblages vary considerably from site to site and within a single site; even within a single sample more than one degree of preservation was observed. It was possible, however, to construct at least partial stratigraphies for each of the three sites. Because the abundance of radiolarians is high even in extremely poorly preserved assemblages, we conclude that the differences in biogenic silica preservation are the result of postdepositional processes and not productivity. In both Sites 999 and 1001, near the Paleocene/Eocene boundary (Bekoma bidartensis Zone [RP7]), there is a short interval in which the abundance and preservation state of the radiolarians improves relative to overlying and underlying assemblages. In each case the intervals corresponds to the level, identified by calcareous microfossils, as representing changes in paleoceanographic conditions associated with the late Paleocene thermal maximum.