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61.
62.
Winfried Schröder Marcel Holy Roland Pesch Harald Zechmeister Harry Harmens Ilia Ilyin 《Environmental Sciences Europe》2011,23(1):1-14
Background
The vertical migration of phytoplankton was investigated in natural waters using in situ fluorescence profiling, chlorophyll a concentrations and life counts at two study sites differing in coloured dissolved organic matter (cDOM) concentrations. The data from the corresponding water depths (50-cm intervals down to 10 m) and times (hourly, before dawn to sunset, several days) were related to the highly resolved (2 nm) underwater ultraviolet radiation (UVR)/photosynthetic active radiation (PAR) transparency (290 to 700 nm).Results
Chlorophyll a maxima of mainly motile dinoflagellates were observed in situ at all days and at both study sites (open marine, brackish waters), independent on prevailing weather conditions or cDOM concentrations. Phytoplankton migration was triggered solely by irradiance in the 400- to 700-nm wavelength range (PAR) at the particular water depth, irrespective of PAR/UVR ratios and surface UVR (290 to 400 nm), after an illumination period of about 40 min. Interestingly, the PAR tolerance levels of the phytoplankton, which have been lower in cDOM-rich waters, matched their light acclimation values determined by parallel PAM measurements.Conclusions
The response of the phytoplankton to PAR is not a sufficient protection strategy versus increasing UVR levels, which might have wide ecological implications beyond the level of primary producers to impact important ecosystem functions such as the delicate trophic interactions. 相似文献63.
Urs Baumann Gustav Peter Ernst Pletscher Marcel Wettstein 《Environmental Sciences Europe》2003,15(4):227-233
Before waste-water-relevant organic materials are to be found in large quantities, their specific behavior in sewage treatment plants must be known. With the aid of the OECD simulation test #303 A, an estimation of their elimination in biological clarification stages can be made. In this work, an economical and continuous testing system is presented, which consists of a polyester flies bound to an activated biosludge with a high inoculum density, allowing one to measure no only the elimination of individual substances, but also the specific degree of mineralization. The toxicity of the activated biosludge and the nitrifying substances can also be examined. With the described testing procedure, it is possible to determine the rate of degradation within only a few hours. Finally, it can also be seen that it is possible to reliably and continuously determine the rate of anaerobic, biological degradability through the use of such a modified testing procedure. 相似文献
64.
Female ornaments in species with conventional sex roles often indicate individual quality, but the evolutionary forces maintaining
them are less clear. Sexual competition for breeding opportunities may represent an important role for female signals, especially
in polygynous species, but there is little experimental evidence for this. The wing patch size (WPS) of female collared flycatchers
indicates age and body condition and predicts social mating patterns. We challenged nest-building females with decoy females
of varying WPS and found that the aggressive response of residents increased with decoy WPS, suggesting a role for this female
ornament in territorial competition. Our results explain why female WPS predicts territorial distances when mated to a polygynous
male and indicate that the role of WPS in female competitive interactions is similar to that in males of the same population. 相似文献
65.
Due to their high phenotypic plasticity, the expression of secondary sexual characteristics is particularly sensitive to stress.
Here, we investigated the expression of two conspicuous visual signals in great tits (Parus major) in a metal pollution gradient. In three study sites with marked differences in metal contamination (mainly lead, cadmium,
copper and zinc), we compared melanin and carotenoid colouration of great tits. While carotenoid colouration (yellow breast)
was negatively related to metal pollution, the size of a melanin trait (breast stripe) was larger in the most polluted sites.
Environmental pollutants not only affect the expression of conspicuous signals but may even enhance, directly or indirectly,
a signal of male quality such as breast stripe. Our results also support the multiple messages hypothesis predicting that
different signals highlight different aspects of geno- and phenotypic condition of the bearer. 相似文献
66.
Marcel Clusa Carlos Carreras Marta Pascual Stephen J. Gaughran Susanna Piovano Cristina Giacoma Gloria Fernández Yaniv Levy Jesús Tomás Juan Antonio Raga Fulvio Maffucci Sandra Hochscheid Alex Aguilar Luis Cardona 《Marine Biology》2014,161(3):509-519
Loggerhead turtles nesting in the Mediterranean Sea exhibit remarkable genetic structuring. This paper tests the hypothesis that young loggerhead turtles from different rookeries do not distribute homogeneously among the major Mediterranean foraging grounds, due to a complex pattern of surface currents. We extracted long fragments of mitochondrial DNA from 275 stranded or bycaught juvenile turtles from six foraging grounds (Catalano-Balearic Sea, Algerian basin, Tyrrhenian Sea, Adriatic Sea, northern Ionian Sea and southern Levantine Sea). We used a Bayesian mixed-stock analysis to estimate the contributions from rookeries in the Mediterranean, the North-west Atlantic and Cape Verde to the studied foraging grounds. Differences were found in the relative contribution of juvenile turtles of Atlantic and Mediterranean origin to each foraging ground. A decreasing proportion of Atlantic juveniles was detected along the main surface current entering the Mediterranean, with a high prevalence of turtles from eastern Florida in the Algerian basin and lower numbers elsewhere. In regard to the turtles of Mediterranean origin, juveniles from Libya prevailed in central and western Mediterranean foraging grounds other than the Algerian basin. Conversely, the Adriatic Sea was characterised by a large presence of individuals from western Greece, while the southern Levantine Sea was inhabited by a heterogeneous mix of turtles from the eastern Mediterranean rookeries (Turkey, Lebanon and Israel). Overall, the distribution of juveniles may be related to surface circulation patterns in the Mediterranean and suggests that fisheries might have differential effects on each population depending on the overlap degree between foraging and fishing grounds. 相似文献
67.
Marie-Lise Schläppy Sandra I. Schöttner Gaute Lavik Marcel M. M. Kuypers Dirk de Beer Friederike Hoffmann 《Marine Biology》2010,157(3):593-602
Aerobic and anaerobic microbial key processes were quantified and compared to microbial numbers and morphological structure
in Mediterranean sponges. Direct counts on histological sections stained with DAPI showed that sponges with high microbial
abundances (HMA sponges) have a denser morphological structure with a reduced aquiferous system compared to low microbial
abundance (LMA) sponges. In Dysidea avara, the LMA sponge, rates of nitrification and denitrification were higher than in the HMA sponge Chondrosia reniformis, while anaerobic ammonium oxidation and sulfate reduction were below detection in both species. This study shows that LMA
sponges may host physiologically similar microbes with comparable or even higher metabolic rates than HMA sponges, and that
anaerobic processes such as denitrification can be found both in HMA and LMA sponges. A higher concentration of microorganisms
in the mesohyl of HMA compared to LMA sponges may indicate a stronger retention of and, hence, a possible benefit from associated
microbes. 相似文献
68.
The complex songs of songbirds are thought to have evolved through sexual selection. Sexually selected signals must be associated
with costs in order to ensure their honesty as indicator of male quality. Costs may relate to the development of the neural
substrate underlying song learning, which develops already very early in life. Song may, therefore, serve as an indicator
of the early developmental history. This nutritional stress hypothesis has initially been confirmed for a variety of species,
but recent studies using zebra finches as a model species reported somewhat inconsistent effects, and the functional consequences
of changes in adult song phenotype remain unclear. We tested the nutritional stress hypothesis in canaries by manipulating
either the brood size or the food quality postfledging. The brood size manipulation had a significant effect on early development,
and low food quality postfledging led to a transient reduction in body mass. However, we did not find evidence that any of
the song traits measured reflected the early developmental conditions, which is in conflict with the nutritional stress hypothesis.
Canaries may be less vulnerable to nutritional stress or are able to compensate stressful conditions during early development.
However, if males compensated, this compensation may have come at a survival cost. Female mate choice decisions were independent
of the developmental history of a male. Instead, females preferred males singing longer song bouts, a trait that may contain
a heritable component. 相似文献
69.
Iserbyt Arne Eens Marcel Baetens Wendy Vermeulen Anke Müller Wendt 《Behavioral ecology and sociobiology》2017,71(4):1-15
Behavioral Ecology and Sociobiology - An individual’s home range, or how much space it requires to obtain resources and meet its needs for survival and reproduction, affects the scale of many... 相似文献
70.
Mehrey G. Vaghti Marcel Holyoak Amy Williams Theresa S. Talley Alexander K. Fremier Steven E. Greco 《Environmental management》2009,43(1):28-37
Societal constraints often limit full process restoration in large river systems, making local rehabilitation activities valuable
for regeneration of riparian vegetation. A target of much mitigation and restoration is the federally threatened Valley elderberry
longhorn beetle and its sole host plant, blue elderberry, in upper riparian floodplain environments. However, blue elderberry
ecology is not well understood and restoration attempts typically have low success rates. We determined broad-scale habitat
characteristics of elderberry in altered systems and examined associated plant species composition in remnant habitat. We
quantified vegetation community composition in 139 remnant riparian forest patches along the Sacramento River and elderberry
stem diameters along this and four adjacent rivers. The greatest proportion of plots containing elderberry was located on
higher and older floodplain surfaces and in riparian woodlands dominated by black walnut. Blue elderberry saplings and shrubs
with stems <5.0 cm in diameter were rare, suggesting a lack of recruitment. A complex suite of vegetation was associated with
blue elderberry, including several invasive species which are potentially outcompeting seedlings for light, water, or other
resources. Such lack of recruitment places increased importance on horticultural restoration for the survival of an imperiled
species. These findings further indicate a need to ascertain whether intervention is necessary to maintain functional and
diverse riparian woodlands, and a need to monitor vegetative species composition over time, especially in relation to flow
regulation. 相似文献