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  • 1975-1979  (16)
  • 1905-1909  (2)
  • 1
    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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  • 2
    Electronic Resource
    Electronic Resource
    Genetic variation and biochemical systematics in the marine bryozoan Alcyonidium mytili (1978)
    Springer
    Marine biology 49 (1978), S. 343-350 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract For many years the taxonomic position of the marine ctenostome bryozoan Alcyonidium mytili Dalyell (1848) has been in doubt, with some authorities regarding it as being conspecific with A. polyoum (Hassall). We have set out to resolve this problem using enzyme electrophoresis to examine the genetics of the population structure in the two “species”. The results show beyond reasonable doubt that sympatric populations of the two species are indeed from quite separate and non-interbreeding gene pools. An examination of various allopatric populations shows a new species of “A. mytili” to exist sympatrically with the other at Langstone Harbour, Hampshire, England. This species can be readily distinguished on morphological as well as genetic ground. Samples of “A. mytili” from Guernsey also show substantial genetic differences from other populations examined. It is tentatively concluded that this population also represents a separate gene pool and consequently should be recognised as a third species of “A. mytili”.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00455029
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  • 3
    Electronic Resource
    Electronic Resource
    The role of food particle size in the growth of juvenile Atlantic salmon (Salmo salar L.) (1979)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 14 (1979), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The effect of particle size of a commercial pelleted feed on the growth of Atlantic salmon from first feeding alevins to first and second year smolts was investigated using 20-day feeding experiments. Ten experiments were performed over a two year period, each comprising six groups of fish separately selected from stock populations. Each group was presented with one of six sizes of food particle ranging from larger than the respective mean mouth breadth (100% feed size), through 50%, 25%, 12·5%, 6·25% to 3·125%. Experiments were performed in six radial flow/circumferential drain tanks under ambient photoperiod and water temperature. Growth rate was found to be closely related to feed size. Maximum growth in each case was shown only on one size of particle; larger and smaller sizes resulted in reduced growth. The particle size for maximum growth increased in direct proportion to fish length. Fish from 4·2 to 20·3 cm in length showed maximum growth on particle diameters 0·022 to 0·026 × fish fork length (PFR). First feeding alevins were found to show comparable growth rate on particle diameters 0·0115 to 0·090 PFR. Some seasonal variation in growth response was indicated. The results are discussed in relation to developmental and seasonal effects. Possible factors affecting the energetics of prey size related differential growth are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1979.tb03530.x
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  • 4
    Electronic Resource
    Electronic Resource
    Biochemical genetics and taxonomy in Plumatella fungosa and P. repens (Bryozoa: Phylactolaemata) (1979)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 9 (1979), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY. Some authors have recently concluded that, using morphological criteria, the freshwater bryozoans Plumatella repens and P. fugosa cannot be separated and should be regarded as conspecific. To test this conclusion, electrophoretic techniques have been used to examine genetic differences between the two nominate species at several enzyme loci. Significant variation at a malate dehydrogenase locus and three aminopeptidase loci establish beyond doubt that P. repens and P. fugosa are separate but related species. No significant variation was found between two populations of P. repens. Morphological characters for the distinction of the two species are discussed and evaluated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1979.tb01498.x
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  • 5
    Electronic Resource
    Electronic Resource
    Monel versus Silver Wire for the Attachment of Disc Tags to Trout (1975)
    Oxford, UK : Blackwell Publishing Ltd
    Aquaculture research 6 (1975), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Monel wire and silver wire have been compared as attachment materials for disc tags on brown trout, Salmo trutta L. Results show monel wire to be quite as suitable as silver, and only 1/30th of the cost.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2109.1975.tb00156.x
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  • 6
    Electronic Resource
    Electronic Resource
    Periodicity in Atlantic salmon Salmo salar L. smolt migration (1978)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 12 (1978), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Behavioural and physiological mechanisms postulated for the control of downstream migration of Atlantic salmon smolts are reviewed briefly, and some new evidence is presented for their refusal to undergo sustained swimming. Although these mechanisms imply passive displacement as the primary means of emigration, it is likely that active components must also exist as the rates of travel of smolts through loch systems are only slightly slower than those recorded for river systems. The timing of these movements within 24 h periods is reviewed and it is shown that the predominantly nocturnal emigration pattern is evident on occasions in alevin, fry and parr stages also. Thus at migration the diel periodicity probably represents a seasonal locomotor rhythm which, under changed behavioural and physiological circumstances, results in downstream displacement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1978.tb04200.x
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  • 7
    Electronic Resource
    Electronic Resource
    Ultrasonic tracking of the movements of atlantic salmon smolts (Salmo salar L) in the estuaries of two Scottish rivers (1978)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 12 (1978), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Ultrasonic telemetry was used to follow the movements of two groups of smolts in the estuaries of two small Scottish rivers. Hatchery reared smolts released into a typical wedge flow, partially mixed estuary had movements which were dominated by the influence of tide on the direction of water flow. The net movements of wild native smolts in a two layer flow estuary, in which freshwater flow dominated, was downstream but were intermittent consisting of short steps and numerous long pauses. The hatchery reared smolts escaped from the estuary within a tidal cycle, moving out on an ebb tide. The wild smolts remained in the estuary for periods up to 108 h, none escaping within one tidal cycle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1978.tb04204.x
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  • 8
    Electronic Resource
    Electronic Resource
    Daily ration of adult perch, Perca fluviatilis L. during summer in Loch Leven, Scotland (1977)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 11 (1977), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Adult perch, Perca fluviatilis L., were sampled at 3-hourly intervals throughout 24-h periods from June-September 1971, and in June and August 1972. The wet weight of each major food component from the stomachs was expressed in parts per 10 000 of the fresh weight of the fish. From samples at capture, and others taken from caged fish at known time-intervals after capture, the rate of stomach evacuation was estimated. Food consumption between netting times was calculated as the increment between successive initial values of stomach contents, plus the amount evacuated in the interval. As the evacuation rate of caged fish was slower than that of free fish the estimates of food turnover are minimal ones. The perch were consuming 6.5 % of their wet body weight per day in June, and this ration had decreased to 3.2% by September.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1977.tb04098.x
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  • 9
    Electronic Resource
    Electronic Resource
    Parental influence on growth rate, smolting rate and survival in hatchery reared juvenile Atlantic salmon, Salmo salar (1978)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 13 (1978), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The proportion of potential 1-year smolts, their mean length, the mean length of potential 2-year smolts, and the mortality rate in four half-sib families of Atlantic salmon, reared under four contrasted conditions of overhead cover, is shown to be inffuenced primarily by genetic factors (89.9%, 86.1 %, 82.7% and 80.2% of total variance respectively). Variation between families in smolting rate and mortality rate is influenced by both parents, but more by the male than the female. Variation in mean length is influenced almost entirely by the female parent. These results are discussed in relation to previous findings on bimodality of size distribution and inheritance of growth and mortality characteristics in Atlantic salmon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1978.tb03467.x
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  • 10
    Electronic Resource
    Electronic Resource
    Bimodal distribution of length of juvenile Atlantic salmon (Salmo salar L.) under artificial rearing conditions (1977)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 11 (1977), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In 52 populations of juvenile Atlantic Salmon, Salmo salar L., from 14 pairings of wild parents, reared at the Almondbank smolt rearing station between 1973 and 1976 in circular radial-flow tanks, bimodality in the frequency distribution of length and weight has been characteristic by the first autumn of growth, and has become progressively clearer during the following winter.The examination of 13 populations showed the modes did not correspond to separate sexes, from four others it was shown they did not correspond to immature fish and precociously mature males. It is suggested that the two modes correspond to subpopulations smoltifying at ages (t) and (t+1) years. The age-composition of the smolt-run originating from individual year-classes of salmon in four Scottish rivers was found to be consistent with stocks having size-group segregations, at the time of the first smolt emigration, similar to those found among Almondbank experimental material. It is inferred that bimodality of size distribution is the norm among sibling populations of juvenile Atlantic salmon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1977.tb04111.x
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