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  • 1
    Electronic Resource
    Electronic Resource
    Specific gravity and shrinkage of open grown Ponderosa pine (1968)
    Springer
    Wood science and technology 2 (1968), S. 292-298 
    Details
    ISSN: 1432-5225
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Zusammenfassung An Holz von Zweitwuchs-Ponderosa pine wurden die Rohdichte und die Schwindung bestimmt. Zu diesem Zweck wurden in Abständen von 4.8 m Stammscheiben entnommen. Das Holz dieser Bäume unterschied sich von jenen aus Altbeständen mit engen Jahrringen durch etwas niedrigere Rohdichtewerte sowie etwas niedrigere Radial-und Tangentialschwindung und durch etwas höhere Werte der Längsschwindung. Das Holz der aus dem Stammfuß entnommenen Scheiben erwies sich als dichter und zeigte häufig anormal hohe Schwindung und unregelmäßigen Faserverlauf. In den höher gelegenen Stammteilen beschränkte sich die übernormale Längsschwindung auf den Kernteil mit rund 25... 50 mm Durchmesser, d. h. auf den Bereich der ersten 2... 3 Jahrringe. Von diesen Ausnahmen ab-gesehen, zeigte das weitringige Holz eine ziemlich gleichmäßige Qualität. In diesem Zusammenhang wird empfohlen, den Fällungsschnitt etwas höher als gewölnlich anzusetzen, wenn es darauf ankommt, auch für den Erdstamm gleichmäßigere Holzqualität zu erzielen.
    Notes: Summary Wood specific gravity and shrinkage determinations were made on disks cut at 16-foot intervals from eight open-grown wide ringed second-growth ponderosa pines. This wood differed from forest grown narrower-ringed wood by having somewhat lower values for specific gravity and radial and tangential shrinkage and slightly higher values for axial shrinkage. Wood from the lowermost (stump) disks was denser and often had excessive axial shrinkage and irregular grain. At higher levels in the tree excessive axial shrinkage was limited to a 1... 2-inch core including the first 2... 3 growth rings. With these exceptions, the wideringed wood was uniform in quality. Slightly higher stumps were advocated if more uniform quality along the length of the butt log is desired.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00350275
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  • 2
    Electronic Resource
    Electronic Resource
    Diel trophic interactions between vertically-migrating zooplankton and their fish predators in an eelgrass community (1978)
    Springer
    Marine biology 48 (1978), S. 207-213 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Diel changes in the composition of crustacean zooplankton and the diets of fish predators from an intertidal eelgrass flat were monitored concurrently. The zooplankton is characterized by two major components. The obligate zooplankters (holoplanktonic calanoid copepods and meroplanktonic decapod larvae) appear to exhibit vertical migration, being present in higher densities near the surface of the water column at night. The facultative zooplankton (amphipods and ostracods) are benthic during the day, but move up into the water column at night. Planktivorous midwaterdwelling fish consume calanoid copepods and decapod larvae during the day and cease feeding or switch their diet to amphipods at night. Benthic-dwelling fish consume some amphipods during both day and night. The factors important in prey selection by fish and the functional significance of vertical migration in both components of the zooplankton are discussed in the light of the changing patterns of fish predation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397146
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  • 3
    Electronic Resource
    Electronic Resource
    Diel variation in the abundance of epifauna associated with seagrasses of the Indian River, Florida, USA (1987)
    Springer
    Marine biology 96 (1987), S. 137-142 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Day-night comparisons of the motile epifauna in the canopy of seagrass beds in the Indian River lagoon, Florida revealed that abundances were not stable over the diel period. Collections were made between February and June, 1982. Higher densities of epifauna occurred on seagrasses at night. For both of the numerically-dominant gastropod and crustacean groups, four of the five top ranked species followed this diel pattern. Crustaceans showed particularly large changes in abundance, averaging a twofold increase in nocturnal samples. Faunal similarity between day and night collections remained high, however, indicating that community structure was preserved during diel abundance changes. Equating epifauna collected from seagrass blades with those associated with the seagrass habitat in general therefore may be erroneous, particularly if collections are made during daylight. Changes in prey availability due to the diel pattern are likely to extend to important community trophic functions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00394847
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  • 4
    Electronic Resource
    Electronic Resource
    Population growth of a gorgonian coral: equilibrium and non-equilibrium sensitivity to changes in life history variables (1991)
    Springer
    Oecologia 86 (1991), S. 503-509 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A size dependent model of population growth of the Caribbean gorgonian Plexaura A is developed based on observed rates of survival, growth and colony fragmentation at a site in the San Blas Islands, Panama. Sensitivity and elasticity analyses indicate that the fate of large colonies has the greatest effect on population growth. Variables which directly affect the generation of large colonies have the next greatest effect on population growth. These variables include the recruitment of large fragments, and the survivorship of colonies in the next smaller size class. Sexual reproduction has an extremely limited ability to affect population growth. Vegetative reproduction has a greater potential effect on growth rates. Environmental conditions regularly change the matrix of transition probabilities which predicts population growth. This keeps the population from approaching its stable size class distribution. Deviations from the stable size class distribution alter sensitivity and elasticity and in this case have the effect of increasing the importance of survivorship of the smallest colonies. Nonequilibrium conditions alter sensitivity analyses and it is important to assess whether populations are at equilibrium and to determine the effects of such deviations on the sensitivity analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318316
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  • 5
    Electronic Resource
    Electronic Resource
    Reproductive success in the Caribbean octocoral Briareum asbestinum (1992)
    Springer
    Marine biology 114 (1992), S. 157-163 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract For most sessile marine invertebrates the number of offspring produced by an individual is often determined indirectly from counts of eggs present, with the assumption that all or most become viable offspring. Few field data on the actual number of offspring produced per individual (reproductive success) have been reported. We examined reproductive success in the octocoral, Briareum asbestinum (Pallas), by measuring embryo densities on 40 female colonies on two reefs (Pinnacles and House reefs) in the San Blas Islands, Panama from 1986 to 1988. The percentage of female colonies with mature eggs which subsequently released embryos was low, ranging from 46.6% in 1986 to 5.0% in 1988. Reproductive success was significantly different between reefs. Pinnacles reef had significantly more successful colonies (those releasing embryos) than House reef in all three years and significantly higher embryo densities in 1986 and 1987. There was a significant positive correlation between female reproductive success and the density and proximity of nearby males in both 1986 and 1987. In addition, fertile female branches placed 25 cm away from male branches produced significantly more embryos than female branches placed 50 cm away. In 1988 two groups of female branches were placed at distances of 〈50 cm and 5 m from four large male colonies at Pinnacles reef. Of the 20 female branches placed 5 m from the males none released embryos while 35% (7 of 20 branches) of the branches 〈50cm from males released embryos. These data indicate that simple counts of mature eggs present within female colonics prior to the reproductive season provide a poor estimate of reproductive success in B. ashestinum and that female reproductive success is positively influenced by the close proximity of males.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00350865
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  • 6
    Electronic Resource
    Electronic Resource
    DNA fingerprints of a gorgonian coral: a method for detecting clonal structure in a vegetative species (1992)
    Springer
    Marine biology 114 (1992), S. 317-325 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Clonal reproduction, a common life history strategy among sessile marine invertebrates, can lead to high local abundances of one to a few genotypes in a population. Analysis of the clonal structure of such populations can provide insight into the ecological and evolutionary history of the population, but requires markers that can identify individual genets. Forensic and demographic studies have demonstrated that DNA fingerprinting can provide markers that are unique for an individual genotype. We have generated DNA fingerprints for over 70 colonies of the clonal gorgonian, Plexaura A (Plexaura sp. A) collected from June 1990 through July 1991 in the San Blas Islands, Panama. DNA fingerprints within a singic individual were identical and fingerprinting resolved multiple genotypes within and among reefs. On one reef in the San Blas Islands, Panama, 59% of the colonies sampled were of one genotype and this genotype was not found on any other sampled reefs. A previous study using tissue grafts identified 13 putative clones on these reefs, while DNA fingerprints of the same colonies differentiated 17 genotypes. The present study demonstrates the utility of DNA fingerprinting for distinguishing clones and for identifying clonal structure of marine invertebrate populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349534
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  • 7
    Electronic Resource
    Electronic Resource
    Production of soldiers and maintenance of soldier proportions by laboratory experimental groups ofReticulitermes flavipes (Kollar) andReticulitermes virginicus (Banks) (Isoptera:Rhinotermitidae) (1981)
    Springer
    Insectes sociaux 28 (1981), S. 32-39 
    Details
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Resume Les effets dûs à la taille du groupe, à l'époque de l'année et aux proportions initiales de soldats ont été explorés dans des groupes expérimentaux deReticulitermes flavipes (Kollar) et deReticulitermes virginicus (Banks). On a élevé des groupes en laboratoire pedant 12 semaines. Les petits groupes (de 500 à 1000 ouvriers) ont produit un plus faible pourcentage de soldats que les grands groupes (de 1500 à 2000 ouvriers). Le nombre de soldats produits dans un groupe est hautement corrélé au nombre total de termites qui survivent. Le pourcentage moyen observé dans tous les groupes a été de 1,75 pour les 2 espèces étudiées. La production de soldats chezReticulitermes flavipes a été la plus élevée dans les colonies prélevées en avril (2%) et la plus faible dans celles prélevées en octobre (0,38%). Les observations bimensuelles des augmentations et des baisses de production de soldats montrent qu'il y a un cycle saisonnier du potentiel de développement. La présence de soldats dans les groupes inhibe la production de nouveaux soldats. Un pourcentage anormalement élevé de soldats n'a pas provoqué l'élimination massive de soldats. De plus, la surcharge des groupes en soldats (plus de 1,75%) n'a pas affecté de façon nuisible la survie du groupe.
    Notes: Summary The effects of group size, time of year, and initial proportions of soldiers were explored in experimental groups ofReticulitermes flavipes (Kollar) andR. virginicus (Banks). Groups were held in the laboratory for 12 weeks. Small groups (500 to 1000 workers) produced a smaller percentage of soldiers than did larger groups (1500 to 2500 workers). The number of soldiers produced in a group is highly correlated with the total number of termites surviving. The average percentage produced for all group sizes was 1.75 for both species. Production of soldiers inR. flavipes was highest in colonies collected in April (2.0%) and lowest in those collected in October (0.38%). Bimonthly observations of increases and decreases in soldier production indicate a seasonal cycle in developmental potential. Presence of soldiers in groups inhibited the production of new soldiers. An abnormally high percentage of soldiers did not precipitate extensive elimination of soldiers. In addition, overloading groups with soldiers (more than 1.75%) did not adversely affect group survival.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02223620
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  • 8
    Electronic Resource
    Electronic Resource
    Bleaching of reef coelenterates in the San Blas Islands, Panama (1984)
    Springer
    Coral reefs 3 (1984), S. 183-190 
    Details
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Starting in June 1983, 25 species of hermatypic corals, gorgonians, hydrocorals, anemones and zoanthids in the San Blas Islands, Panama, began showing signs of a loss of colour leading in some cases to a white “bleached” appearance. Histologic examination of six coral species indicated that bleaching was associated with drastic reductions in the density of zooxanthellae and with the atrophy and necrosis of the animal tissue. The severity of the bleaching varied among species and many species were unaffected. The species most extensively affected were: Agaricia spp., which became completely bleached and frequently died; Montastraea annularis which bleached and continued to survive; and Millepora spp. which bleached white but quickly regained their colouration. Shallow reefs dominated by Agaricia spp. suffered the most extensive bleaching. At one site, Pico Feo, 99% of the Agaricia (32% of the living cover) was bleached. On fore reers, which were dominated by Agaricia spp. and M. annularis, the proportion of M. annularis bleached ranged from 18 to 100% and that of Agaricia spp. from 30 to 53%. Transects at Sail Rock and House Reef were surveyed in August 1983 and January 1984. At those sites, 53% of the Agaricia cover died between August and January. The remaining living cover of Agaricia and of all other species exhibited normal colouration in January. Salinity and temperature were monitored every second day at 4 m depth between May 10 and August 28, 1983 at one of the localities. Bleaching was first observed within two weeks of a 2 °C rise in temperature which occurred in late May 1983. Temperatures remained at or above 31.5 °C for the following 3 weeks and were at or above 30 °C for an additional 4 weeks. The bleaching of corals in the San Blas was most likely due to those elevanted temperatures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00288253
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  • 9
    Electronic Resource
    Electronic Resource
    Inter- and intraspecific variation in gorgonian colony morphology: quantifying branching patterns in arborescent animals (1988)
    Springer
    Coral reefs 7 (1988), S. 139-143 
    Details
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Geomorphological methods for quantifying branching networks are used to describe inter- and intra-specific differences in branching patterns among two species of arborescent Caribbean gorgonian, Plexaura homomalla, P. flexuosa, and a third, undescribed plexaurid from the San Blas Islands, Panama. There were significant differences among species for first, second and third order branch lengths, and for tributary to source ratios for first and second order branches. Extrapolations from the branching parameters successfully predicted differences in the branch structure of naturally generated colony fragments. Within P. homomalla, significant differences with depth in the lengths and tributary to source ratios of first, second, and third order branches provide a measure of the greater bushiness of shallow water colonies. These measures can be used to quantify morphological differences in both ecological and systematic analyses. Data on the branching characters of these three gorgonian species demonstrate that gross colony form can be studied as a quantifiable component of phenotype and that gorgonians display both species level and ecophenotypic variation in colony form.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00300973
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  • 10
    Electronic Resource
    Electronic Resource
    Prostaglandin synthetase inhibitors in insect defensive secretions (1986)
    Springer
    Naturwissenschaften 73 (1986), S. 735-737 
    Details
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00399245
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