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81.
The total lipid and wax ester content as well as the fatty acid and alcohol composition of all copepodid stages and adults of Calanus finmarchicus s.l. were investigated at different locations in the North Sea in 1983 and 1984. Total lipid and the wax ester proportion increased exponentially until Copepodid V. The females were sometimes lower in lipids than the Stage V. The wax ester proportion reached about 90% of total lipids in males and Copepodid V and up to 40% in Copepodid I. The major fatty acids were 16:0, 20:5, and 22:6 and the major fatty alcohols were 16:0, 20:1 and 22:1. At one station the 18:4 acid became one of the dominant acids, because of a Phaeocystis sp. bloom, indicating that the fatty acids of the diet are incorporated mostly unchanged into the lipids of the copepods. The other main fatty acids 20:1 and 22:1 are probably synthesized de novo, serving as precursors for the principal alcohols 20:1 and 22:1. Their levels decreased in the younger stages due to increases in 16:0 alcohol. The fatty alcohol-forming enzyme seems to be specific for saturated and monounsaturated acids, which may be synthesized de novo or derived from diet. 相似文献
82.
To evaluate the effects of dry and wet deposition on forest trees (Picea abies [L.] Karst.), the LIS-Essen is operating an Open-Top Chamber Field Station within an area where novel forest decline has been prevalent since 1982. Chambers are ventilated with either ambient or charcoal-filtered air and receive either natural or artificial rain, the latter being prepared by natural rain and distilled water in ratio 1:10. Besides deposition data, acquired above and below the tree crowns as well as via lysimeters of soil percolates, various parameters describing vitality of trees are measured. To obtain a persuading representation of total parameters and their interdependencies, a multivariate graphical cluster analysis has been performed by use of Chernoff-Flury faces. Interdependencies of vitality parameters are more easily recognizable in this multivariate picture than in usually applied binary correlation diagrams. 相似文献
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85.
Doug M. Boyer Guntupalli V. R. Prasad David W. Krause Marc Godinot Anjali Goswami Omkar Verma John J. Flynn 《Die Naturwissenschaften》2010,97(4):365-377
Extant species of the supraordinal mammal clade Euarchonta belong to the orders Primates, Scandentia, or Dermoptera. The fossil
record of euarchontans suggests that they underwent their initial radiation during the Paleocene (65–55 million years ago)
in North America, Eurasia, and Africa. The time and place of origin is poorly resolved due to lack of definitive fossils of
euarchontan stem taxa. We describe a fragmentary humerus and two fragmentary ulnae from the latest Cretaceous of India that
bear significantly on this issue. The fossils are tentatively referred to Deccanolestes cf. hislopi due to their small size and the fact that Deccanolestes is the only eutherian dental taxon to have been recovered from the same locality. The new fossils are used to evaluate the
existing behavioral hypothesis that Deccanolestes was arboreal, and the competing phylogenetic hypotheses that Deccanolestes is a stem eutherian versus a stem euarchontan. The humerus resembles those of euarchontans in possessing a laterally keeled
ulnar trochlea, a distinct zona conoidea, and a spherical capitulum. These features also suggest an arboreal lifestyle. The
ulnar morphology is consistent with that of the humerus in reflecting an arboreal/scansorial animal. Detailed quantitative
comparisons indicate that, despite morphological correlates to euarchontan-like arboreality, the humerus of Deccanolestes is morphologically intermediate between those of Cretaceous “condylarthran” mammals and definitive Cenozoic euarchontans.
Additionally, humeri attributed to adapisoriculids are morphologically intermediate between those of Deccanolestes and definitive euarchontans. If adapisoriculids are euarchontans, as recently proposed, our results suggest that Deccanolestes is more basal. The tentative identification of Deccanolestes as a basal stem euarchontan suggests that (1) Placentalia began to diversify and Euarchonta originated before the Cretaceous–Tertiary
boundary and (2) the Indian subcontinent, Eurasia, and Africa are more likely places of origin for Euarchonta than is North
America. 相似文献
86.
Uta Berger Marion Glaser Boris Koch Gesche Krause Rubén Lara Ulrich Saint-Paul Dirk Schories Matthias Wolff 《Journal of Coastal Conservation》1999,5(2):125-134
The main objective of the MADAM project (Mangrove Dynamics and Management) is to generate the scientific basis enabling the
sustainable stewardship of the resources of the Caeté mangrove estuary in Northeast Brazil in the sense of integrated coastal
(zone) management. To achieve this, it is necessary to acquire in-depth knowledge of natural processes as well as of the relevant
institutional, cultural, economic, social and political dynamics. Causal linkages within the ecosystem, as well as between
ecosystem, economy and society, are analysed and explained via dynamic and trophic modelling. Scenario construction is intended
to forecast the effects of acute or chronic interference on utilized resources, and to answer wider, management-related questions
(e.g. restoration of destroyed areas, utilization potential for aquaculture). This paper describes the project strategy as
developed and modified in the context of research results from the initial 2-yr project phase. It is argued that a continuous
discussion process is essential to assess the validity of the strategies formulated at the beginning of a medium-time project,
particularly if the project is of interdisciplinary nature. 相似文献
87.
The inarticulated brachiopod, Lingula reevii Davidson (1880) is a filter-feeding invertebrate that burrows vertically in sandy or mixed sediments. Its only recorded occurrence
is from Kaneohe Bay, Oahu, Hawaii, southern Japan, and Ambon, Indonesia. Past surveys of Kaneohe Bay populations suggested
a distinct decrease in abundance following the diversion of sewage effluent from the bay in 1978/1979. In the summer of 2004
and 2007, visual surveys were conducted in areas of historical L. reevii abundance as well as in areas appearing to have suitable habitat. In 2004, approximately 2,950 m2 at 20 sites within the bay were surveyed using quantitative belt transecting methods. A maximum density of 4 Lingula/m2 was observed, a decrease from previous maximum estimates of 500 individuals/m2 (Worcester, Dissertation, Zoology Department, University of Hawai′i, pp 49, 1969) and 100 individuals/m2 (Emig, J Exp Mar Biol Ecol 52:47–61, 1981). When these 20 sites were revisited in 2007, many had fewer or no L. reevii; therefore, broader scale presence/absence surveys were conducted at 16 additional sites in the bay (also surveyed in 2004).
The highest density of L. reevii found in 2007 was 0.94 individuals/m2. The continued decline in abundance of L. reevii in Kaneohe Bay may be due, in addition to decreased organic enrichment from diversion of sewage discharge almost 30 years
ago, to the more recent reduction of suitable habitat by the invasion of mat-forming alien algae species. 相似文献
88.
Darren P. Croft Jens Krause Safi K. Darden Indar W. Ramnarine Jolyon J. Faria Richard James 《Behavioral ecology and sociobiology》2009,63(10):1495-1503
The social fine structure of a population plays a central role in ecological and evolutionary processes. Whilst many studies
have investigated how morphological traits such as size affect social structure of populations, comparatively little is known
about the influence of behaviours such as boldness and shyness. Using information on social interactions in a wild population
of Trinidadian guppies (Poecilia reticulata), we construct a social network. For each individual in the network, we quantify its behavioural phenotype using two measures
of boldness, predator inspection tendency, a repeatable and reliably measured behaviour well studied in the context of co-operation,
and shoaling tendency. We observe striking heterogeneity in contact patterns, with strong ties being positively assorted and
weak ties negatively assorted by our measured behavioural traits. Moreover, shy fish had more network connections than bold
fish and these were on average stronger. In other words, social fine structure is strongly influenced by behavioural trait.
We assert that such structure will have implications for the outcome of selection on behavioural traits and we speculate that
the observed positive assortment may act as an amplifier of selection contributing to the maintenance of co-operation during
predator inspection. 相似文献
89.
The confusion effect describes the observed decrease in the likelihood that a predator will successfully catch any prey when
attacking larger groups of moving prey. We introduce readers to the work of cognitive psychologists interested in human visual
attention who have been studying their own version of the confusion effect for many years, developing methods and concepts
that may be of fundamental utility to behavioral ecologists. In psychology, ‘basic features’ are characteristics unique to
a target object in the visual field that no distracter objects share. Images containing targets with basic features are often
less likely to induce the confusion effect in human subjects. Target objects with conjunctions of features, on the other hand,
have no individual characteristics unique from distracters, but unique characteristics in combination. Such targets more often induce the confusion effect in humans. We propose the ‘basic feature’ (vs. conjunctions of features)
as a new organizing concept for studies on the occurrence of the confusion effect in nature, potentially allowing predictions
about which types of prey groups are likely to induce the confusion effect in predators. 相似文献
90.
Increased carbon dioxide availability alters phytoplankton stoichiometry and affects carbon cycling and growth of a marine planktonic herbivore 总被引:1,自引:0,他引:1
Katherina L. Schoo Arne M. Malzahn Evamaria Krause Maarten Boersma 《Marine Biology》2013,160(8):2145-2155
Rising levels of CO2 in the atmosphere have led to increased CO2 concentrations in the oceans. This enhanced carbon availability to the marine primary producers has the potential to change their nutrient stoichiometry, and higher carbon-to-nutrient ratios are expected. As a result, the quality of the primary producers as food for herbivores may change. Here, we present experimental work showing the effect of feeding Rhodomonas salina grown under different pCO2 (200, 400 and 800 μatm) on the copepod Acartia tonsa. The rate of development of copepodites decreased with increasing CO2 availability to the algae. The surplus carbon in the algae was excreted by the copepods, with younger stages (copepodites) excreting most of their surplus carbon through respiration and adult copepods excreting surplus carbon mostly as DOC. We consider the possible consequences of different excretory pathways for the ecosystem. A continued increase in the CO2 availability for primary production, together with changes in the nutrient loading of coastal ecosystems, may cause changes in the trophic links between primary producers and herbivores. 相似文献