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551.
Francesca Porri Gerardo I. Zardi Christopher D. McQuaid Sarah Radloff 《Marine Biology》2007,152(3):631-637
Settlement is a major determinant of intertidal populations. However, the energy costs of lost larvae are very high. Accordingly,
arrival and attachment on suitable substrata are essential requirements for species’ survival. On the intertidal, the presence
of cues left by adult or juvenile conspecifics could be vital for the successful establishment of larvae arriving on the shore.
Two mussel species, the indigenous Perna perna and the invasive Mytilus galloprovincialis, co-occur on the lower eulittoral zone on the south coast of South Africa. P.
perna dominates the low and M. galloprovincialis the high mussel zones, with co-existence in the mid mussel zone. This study tested the hypothesis of settlement selectivity
for conspecifics in these two mussel species, to understand whether the final adult distribution of mussels on the shores
is determined by active behavioural and chemical mechanisms. Preferential selection by larvae for conspecifics was tested
in the field during the peak settlement period in 2004 in natural mussel beds across zones and through manipulative experiments
in the mid-zone where the species co-exist. On natural beds, settlement was determined by counts of settlers attached over
48 h onto artificial collectors. Collectors were placed on beds of P. perna and M. galloprovincialis present at both high- and low-adult densities, as well as in mixed beds. On such natural beds, settlers of both species consistently
favored low-zone P. perna beds. Settlement patterns over 24 h onto experimentally created mussel patches consisting of P.
perna, M. galloprovincialis or the two species combined beds, set in the mixed zone, did not conform with the results of the natural beds study: settlers
of both species settled with no discrimination among different patches. The results indicate that mussels, which are sedentary,
lack attraction to conspecifics at settlement. This highlights the importance of tidal height in setting settlement rates,
and of post-settlement events in shaping populations of these broadcast spawners. 相似文献
552.
Although many parasites are known to manipulate the behavior of their hosts, the mechanisms underlying such manipulations are largely unknown. Baculoviruses manipulate the behavior of caterpillar hosts by inducing hyperactivity and by inducing climbing behavior leading to death at elevated positions (tree-top disease or Wipfelkrankheit). Whether hyperactivity and tree-top disease are independent manipulative strategies of the virus is unclear. Recently, we demonstrated the involvement of the protein tyrosine phosphatase (ptp) gene of the baculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV) in the induction of hyperactivity in Spodoptera exigua larvae. Here we show that AcMNPV ptp is not required for tree-top disease, indicating that in S. exigua baculovirus-induced hyperactivity and tree-top disease are independently induced behaviors that are governed by distinct mechanisms. 相似文献
553.
A. S. Prokushkin I. V. Tokareva S. G. Prokushkin A. P. Abaimov H. Guggenberger 《Russian Journal of Ecology》2008,39(3):151-159
Fluxes of dissolved organic matter (DOM) in larch biogeocenoses and its export from the drainage basin have been studied in the zone of continuous permafrost. A comparative assessment of DOM input into the soil has been made on slopes of northern and southern exposures (as variants reflecting the current state and warming). The dynamics of DOM export in a creek depending on the increasing depth of the active soil horizon in the drainage area have been revealed. It is concluded that an increase in the depth of the seasonally thawing layer induced by global warming will not have any significant effect on the amount of annual DOM export. Reduction of DOM export may be expected upon a decrease in litter stocks under the effect of their mineralization and forest fires. 相似文献
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557.
Giant reed for selenium phytoremediation under changing climate 总被引:1,自引:0,他引:1
Hassan R. El-Ramady Neama Abdalla Tarek Alshaal Ahmed S. Elhenawy Mohamed S. Shams Salah E.-D. A. Faizy El-Sayed B. Belal Said A. Shehata Mohamed I. Ragab Megahed M. Amer Miklós Fári Attila Sztrik József Prokisch Dirk Selmar Ewald Schnug Elizabeth A. H. Pilon-Smits Samia M. El-Marsafawy Éva Domokos-Szabolcsy 《Environmental Chemistry Letters》2015,13(4):359-380
558.
Size segregated suspended particulate matter (PM2.5 and PM10-2.5) in air at four major petroleum-filling stations in Ile-Ife, Nigeria, were monitored using double staged “Gent” stacked samplers to assess variations in mass loads and elemental concentrations of 25 elements. Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, Zr, Cs, Ta, W, and Pb were determined in both fractions by external ion beam proton-induced X-ray emission technique. Enrichment factors and pollution indices were calculated and results revealed that most elements were anthropogenic in both fractions with concentrations exceeding the World Health Organization guideline standards. 相似文献
559.
560.
El-Shafey EI 《Journal of environmental management》2007,84(4):620-627
A carbonaceous sorbent was prepared from peanut shell via sulphuric acid treatment. Se(IV) removal from aqueous solution on the sorbent was studied varying time, pH, Se(IV) concentration, temperature and sorbent status (wet and dry). Se(IV) removal was faster using the wet sorbent than the dry sorbent following a pseudo-first-order model. Se(IV) removal increases at low pH values, and decreases as pH increases until pH 7. Sorption was found to fit the Langmuir equation and sorption capacity for the wet sorbent was higher than that for the dry one. Both sorbents showed an increased selenium sorption by rising the temperature. Redox processes between Se(IV) and the carbon sorbent are involved. Analysis by scanning electron microscope and X-ray powder diffraction for the sorbent after the reaction with acidified Se(IV) confirmed the availability of elemental selenium as particles on the sorbent surface as a result of Se(IV) reduction. Physicochemical tests showed an increase in sorbent acidity, cation exchange capacity (CEC) and surface functionality after the reaction with acidified Se(IV), indicating the oxidation processes occurring on the sorbent surface. Due to its reduction properties, the sorbent seems efficient for Se(IV) removal from aqueous solution. 相似文献