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  • 1
    Electronic Resource
    Electronic Resource
    Modelling the life-history variation of Arctic charr (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract –  A model based on proximate considerations of life histories of Atlantic salmon, Salmo salar, was examined for its applicability to fit the variation in life-history of wild Arctic charr, Salvelinus alpinus, based on a qualitative assessment of information related to growth and lipid dynamics of Arctic charr. The original salmon model is discussed in context of modifications required to account for added complexities in the life history of Arctic charr in relation to anadromy versus residency. A study from North Norway shows that individual charr that emigrate from the lakes to the sea, maintain a high growth rate in the lake in late summer and early autumn compared with resident fish. Their relatively low lipid level in autumn combined with a high rate of change of lipid during winter was associated with postponement of maturation in the anadromous individuals. Individuals that remain resident in the lake arrested growth in autumn. Their high lipid level in autumn combined with a low rate of change of lipid during winter was associated with maturation the following summer, without emigration from freshwater. Results from this and other related studies show similarities with the model derived from lipid and growth dynamics of Atlantic salmon. The adjusted charr model illustrates possible proximate explanations for the high variation in life-history strategies of Arctic charr. However, the model does not account for the characteristic return migration of immature charr into freshwater several weeks after their entry to the sea. The proximate physiological stimulus for this movement of immature fish is not entirely clear.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00070.x
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  • 2
    Electronic Resource
    Electronic Resource
    Image analysis to measure strain in wood and paper (1991)
    Springer
    Wood science and technology 25 (1991), S. 251-262 
    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
    Notes: Summary A fast and accurate strain measurement method was developed to quantify microscopic deformation in wood and paper using video images. Two or more video images, one of which was undeformed and the others of which were deformed, were digitized and compared using the image correlation technique. This digital computer pattern recognition technique permitted the displacement of any point in the image to be measured. Then, strain between any two points in this observation field could be calculated and, hence, normal, shearing strains and Poisson's ratio could be measured directly. Independent strain measurements showed that the method using video images provided accurate strain measurements and could be applied to complex materials like wood and wood products. The strain measurements using the image analysis produced not only normal strains but strain profiles of the normal strains. From the strain profiles, it was possible to detect local areas of strain concentration which might be beyond the elastic range. As it measures displacements and strains from a set of video images using the image correlation technique, the method is non-contact and the observation field can be adjusted easily by changing magnifying power of the optical devices. Thus, the method can be applied to mechanical testing of wood and wood products from the cellular level to full size lumber and will no longer be limited by the fragile nature of the material being tested, industry standards, or equipment restrictions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225465
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  • 3
    Electronic Resource
    Electronic Resource
    Population differentiation and taxonomic status of the exploited limpet Patella candei in the Macaronesian islands (Azores, Madeira, Canaries) (1996)
    Springer
    Marine biology 125 (1996), S. 141-152 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract There has been considerable confusion in the taxonomy of limpets of the North East Atlantic Ocean and Mediterranean Sea, particularly those from the Macaronesian islands. The present study compared populations of the intertidal limpet Patella candei d'Orbigny from the Azores, Madeira and the Canaries with those of P. caerulea Linnaeus and P. depressa Pennant from the European and African continental coasts. No major differences in radular morphology were detected between the three species. However, electrophoretic analysis of 15 enzyme loci gave overall genetic identity (I) values of ∼0.5 between the three species, indicating that they cannot be regarded as conspecific as previously thought, and suggesting that P. candei is endemic to the Macaronesian islands. Comparisons of P. candei within these islands showed that, although populations did not differ with respect to radular morphology and soft-body parts, populations from the Azores were distinct from those in Madeira and the Canaries in shell shape and gene frequencies. Individuals from the Azores had, no average, taller shells and longer radulae, while those in Madeira and the Canaries had a shallow, depressed and stellate shell form. This was interpreted as being due to the wider habitat distribution of the species in the Azores compared to Madeira and the Canaries. Electrophoretic results showed that P. candei from the Azores differed from P. candei in Madeira and the Canaries by almost 40% of the loci investigated (I=0.660), suggesting that the former is a separate endemic species. An I value of 0.969 between populations in Madeira and the Canaries was typical of conspecific populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00350768
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  • 4
    Electronic Resource
    Electronic Resource
    Genetic evidence for cryptic speciation in the marine bryozoan Alcyonidium gelatinosum (1978)
    Springer
    Marine biology 49 (1978), S. 27-32 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The common subtidal marine bryozoan Alcyonidium gelatinosum (L.) is one of the most confusing species of a taxonomically very difficult genus. It shows massive variation for almost all morphological characters. A number of sympatric colonies collected off the coast of Lundy (Bristol Channel) could be clearly divided on morphological grounds into two quite distinct types. Using starch gel electrophoresis the products of a range of genetic enzyme loci were compared between the two morphotypes and also between these and other Bristol Channel populations of A. gelatinosum. Minimal differences were observed between one Lundy morphotype and the other allopatric populations, which it was consequently concluded were conspecific. The second morphotype showed considerable genetic differentiation [genetic identity (Nei, 1972) =0.417] from the other Lundy population, with no common alleles at some loci. The probability of obtaining the observed results by chance in a single population is significantly low (P〈10−14). It is therefore concluded that the two morphotypes of A. gelatinosum from Lundy are not conspecific.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00390727
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of particle concentration on clearance rate and feeding current velocity in the marine bryozoan Flustrellidra hispida (1983)
    Springer
    Marine biology 77 (1983), S. 85-92 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Colonies of the marine bryozoan Flustrellidra hispida (Fabricius) were collected intertidally from Port St Mary, Isle of Man (UK) during the autumn and winter 1981/1982. Suspension feeding in F. hispida was examined in some detail, using as food the alge Tetraselmis suecica. Previous studies had not examined variation in the speed of suspended food particles travelling through the lophophore. It is clear that feeding rate, as measured by particle velocity, varies over periods of time, even when all external factors are kept constant. Moreover, particle speed within the lophophore can be shown to be positively correlated with the concentration of suspended food particles in the surrounding environment. It is also apparent that feeding current velocity varies at different positions within the lophophore. In addition observations are made on the involvement of the tentacles in particle capture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393213
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  • 6
    Electronic Resource
    Electronic Resource
    Autoradiographic study of feeding and the colonial transport of metabolites in the marine bryozoan Membranipora membranacea (1985)
    Springer
    Marine biology 84 (1985), S. 295-300 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Standard autoradiographic techniques were adapted to study the transport of carbon compounds in colonies of Membranipora membranacea (L.). The results indicate that there is transport of carbon-14 between polypides within a colony. Metabolite movement is generally in the direction of the rapidly growing colony edge. Estimates of metabolite transport rates are given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392499
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  • 7
    Electronic Resource
    Electronic Resource
    A biochemical genetic study of population structure in queen scallop (Chlamys opercularis) stocks in the Northern Irish Sea (1985)
    Springer
    Marine biology 87 (1985), S. 77-82 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Electrophoresis was used to survey a number of enzymes for loci of potential value as stock markers in Chlamys opercularis (L.). Two loci, Pgi and Pgd, were then studied in larger samples from each of two localities around the Isle of Man. One Pgi allele was found to be restricted to a particular year-class in both populations. This was confirmed by subsequent studies of three further populations, in each of which the same allele occurred only in the one year-class. Otherwise, no significant differences in allele frequencies were found between year-classes or between populations in any of the samples used. From the results it is concluded that there is temporal variation in the sources of recruitment of C. opercularis stocks around the Isle of Man. Possible origins of larvae contributing to these stocks are discussed in the light of what is known of current circulation patterns in the northern Irish Sea.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397008
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  • 8
    Electronic Resource
    Electronic Resource
    Reproductive isolation with little genetic divergence between Urticina (=Tealia) felina and U. eques (Anthozoa: Actiniaria) (1985)
    Springer
    Marine biology 85 (1985), S. 279-284 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract There has long been doubt as to whether there are one or two British species of the sea anemone genus Urticina. In the present study, populations of both putative species, which occur sympatrically in the Isle of Man, have been compared by electrophoresis of isozymes and nematocyst analysis. The analysis of fourteen isozyme loci exhibited a high genetic identity between the two taxa (I=0.907), but four loci showed significant differences in gene frequencies; thus indicating reproductive isolation. The populations displayed highly significant differences in the sizes of the various nematocyst types. The individual analysis of data for each type of nematocyst revealed that the basitrics from the actinopharynx and from the tentacles contribute most to the observed difference. Consequently, U. felina (L.) and U. eques (Gosse) are assumed to be valid species, as suggested by Manuel (1981). The mean heterozygosities for each species (0.410 and 0.436, respectively) are the highest reported for cnidarians.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393248
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  • 9
    Electronic Resource
    Electronic Resource
    Genetic differentiation between morphotypes of the marine sponge Suberites ficus (Demospongiae: Hadromerida) (1986)
    Springer
    Marine biology 93 (1986), S. 247-253 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Sponges of three morphotypes of Suberites ficus (Johnston, 1842) were collected during February and March 1985 off the south-west of the Isle of Man, and were compared by using spicule size distributions and genetic allele frequencies of isozyme loci. The populations did not show any significant differences of spicule size or type, but could be easily differentiated into three separate species based on isozyme patterns. Samples of pale orange S. ficus growing on gastropod shells inhabited by hermit crabs (Pagurus spp.) were reproductively isolated from the redorange and the pale yellow colour morphs encrusting the bivalve Chlamys opercularis. These latter two colour morphs were genetically similar, but significant differences were observed at two of the 19 gene loci assayed. All the sponges studied were sympatric, and therefore the genetic differences, indicating reproductive isolation, are strong evidence for separate gene pools and, hence, that they are different species. The genetic identity between the two colour morphs of S. ficus on C. opercularis shells was 0.977, whilst between each of these and S. ficus on hermit crabs it was about 0.65. In all three species genetic variability was high, with mean expected and observed heterozygosity values per locus ranging from 0.17 to 0.36.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00508262
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  • 10
    Electronic Resource
    Electronic Resource
    Effects of food particle concentration on feeding current velocity in sex species of marine Bryozoa (1986)
    Springer
    Marine biology 93 (1986), S. 255-262 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Experiments were carried out using established methods to measure feeding current velocity in six species of marine Bryozoa collected in 1982 and 1983 around low-tide mark at Port St. Mary, Isle of Man (Flustrellidra hispida, Alcyonidium gelatinosum, A. hirsutum, Electra pilosa, Membranipora membranacea and Bowerbankia gracilis feeding on Tetraselmis suecica). It was found that there was a positive correlation between feeding current velocity and the concentration of food (phytoplankton) in the environment. It was also found that, at a fixed particle concentration, feeding current velocity was strongly correlated with lophophore height and (less strongly) with tentacle number. The competitive and evolutionary implications of these relationships are considered. It is tentatively suggested that interspecific competition for food may be of some significance in marine Bryozoa and that the removal of food supplies to competing colonies may play a role in colony overgrowth and competition for space.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00508263
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