Comparison of EDTA-enhanced phytoextraction and phytostabilisation strategies with Lolium perenne on a heavy metal contaminated soil

Phytoremediation is a promising and cost-effective strategy to manage heavy metal polluted sites. In this experiment, we compared simultaneously phytoextraction and phytostabilisation techniques on a Cd and Zn contaminated soil, through monitoring of plant accumulation and leaching. Lolium perenne plants were cultivated for 2 months under controlled environmental conditions in a 27.6 dm³-pot experiment allowing the collect of leachates. The heavy metal phytoextraction was promoted by adding Na-EDTA (0.5 g kg⁻¹ of soil) in watering solution. Phytostabilisation was assessed by mixing soil with steel shots (1%) before L. perenne sowing. Presence of plants exacerbated heavy metal leaching, by improving soil hydraulic conductivity. Use of EDTA for phytoextraction led to higher concentration of heavy metal in shoots. However, this higher heavy metal extraction was insufficient to satisfactory reduce the heavy metal content in soil, and led to important heavy metal leaching induced by EDTA. On the other hand, addition of steel shots efficiently decreased both Cd and Zn mobility, according to 0.01 M CaCl₂ extraction, and leaching. However, improvement of growth conditions by steel shots led to higher heavy metal mass in shoot tissues. Therefore, soil heavy metal mobility and plant metal uptake are not systematically positively correlated.     

Double-brooded great tits (<Emphasis Type="Italic">Parus major</Emphasis>) in Mediterranean oak habitats: Do first broods always perform better than second broods?

Although mistimed reproduction (i.e., time-lag between peak food supply and offspring food demand) has been attributed to habitat modifications or climate change in recent avian investigations, earlier breeding parents have higher reproductive success in many habitats. Here we compare first and second broods in great tits (Parus major L.) from two Mediterranean oak habitats differing significantly in the timing (about 5 weeks), but not the amount of caterpillar supply required to rear chicks. The study indicates that both the extent of mistimed reproduction and the breeding date per se influence breeding performance in this study system. The text was submitted by the authors in English.     

Modelling the fate of marine turtle hatchlings

The SLIM oceanographic model was used to examine the fate of hatchling flatback turtles (Natator depressus) in the first two weeks of their dispersal starting at Wild Duck Island, a major turtle-nesting site in the central Great Barrier Reef region of Australia. We ran simulations to investigate the effects of spring versus neap tides, hatchling's swimming behaviour during their first three days at sea, and the location of nesting beaches. The model predicted that up to 50% of the turtle hatchlings entering the sea from the windward, southern beach remained after 14 days in shallow, nearshore waters, irrespective of tides and swimming. These waters are turbid and may be inhospitable to hatchlings. In contrast >80% of hatchlings dispersing from the leeward, northern beach were dispersed to deeper water (10-40 m) in a quasi-stationary dispersion core centred around 10 km north of the nesting beach after 14 days and the offshore spread of the turtle plume was enhanced by the hatchling's seaward swimming during the first three days. This was due to the presence of a coastal boundary layer and a stagnation zone around the northern side of island, but not the southern side. The model confirmed that dispersal from eastern Queensland flatback turtle rookeries is restricted to the lagoons and coastal waters, and that water circulation and hatchling's swimming control dispersion. The model explains why more turtles nest on the northern than the southern side. This study highlights the usefulness of oceanographic models to increase knowledge about a cryptic life stage of marine turtles.     

Male quality,reproduction, and survival in the great tit (Parus major)

Summary Three possible measures of male quality (social dominance, song, and size), reproduction, and survival were studied in a single population of great tits. Winter dominance position on a feeder was related to strophe length (number of phrases per strophe), inversely related to positive drift (decrease of the singing rate of the phrases in a strophe), but not related to song repertoire size. Neither winter dominance position nor song were related to size (wing length, tarso-metatarsus length, weight).Singing capacity was not correlated with individual reproductive success in a single breeding season, using a rather limited data set. However, better singers (males which sing longer strophes, show less positive drift, and have larger song repertoires) survived better and had a higher individual lifetime reproductive success (on the basis of a male's recruited offspring of all breeding seasons). Our results show that there exist measurable differences whereby birds that are dominant in winter sing better, survive longer, and produce more surviving offspring during their life time. We suggest that differences in male quality are the common cause (direct and indirect) of all these effects.     

An implicit wetting–drying algorithm for the discontinuous Galerkin method: application to the Tonle Sap,Mekong River Basin

Environmental Fluid Mechanics - The accurate simulation of wetting–drying processes in floodplains and coastal zones is a challenge for hydrodynamic modelling, especially for long time...     

Effect of blue tit song syntax on great tit territorial responsiveness – an experimental test of the character shift hypothesis

A previous study of geographic variation in blue tit (Parus caeruleus) song structure showed that changes in blue tit song syntax (i.e. presence/absence of a trill) are correlated with the breeding density of a close competitor, the great tit (P. major), and are not correlated with other environmental factors such as vegetation structure or blue tit breeding density. We tested the hypothesis that blue tit trilled song represents a character shift that evolved because it reduced territorial interactions with more dominant great tits. We conducted five sets of playback trials in three study populations (mainland southern France, Corsica and Denmark) presenting male great tits with blue tit trilled and untrilled songs and great tit songs. We found that great tits respond equally strongly to both blue tit untrilled songs and to great tit songs, but show a significantly weaker response to blue tit trilled songs. These findings are the first experimental evidence that interspecific competition may play an important role in macrogeographic variation of bird song. Received: 10 October 1999 / Received in revised form: 2 April 2000 / Accepted: 15 April 2000