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  • 1
    Electronic Resource
    Electronic Resource
    Ecological energetics of the sea-weed zone in a marine bay on the Atlantic coast of Canada. II. Productivity of the seaweeds (1972)
    Springer
    Marine biology 14 (1972), S. 199-209 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The growth of the seaweeds Laminaria longicruris, L. digitata and Agarum cribrosum were followed by SCUBA divers for two years, by punching holes 10 cm from the junction of stipe and blade, and recording at intervals the distance the holes had moved. As the holes approached the tip of the blade, new holes were punched at the base. It was found that the blades behaved like moving belts of tissue, eroding at the tips while growing at the bases, so that a total year's growth amounted to 1 to 5 times the initial length. Larger, older plants had wider and thicker blades, and the biomassincrease was roughly proportional to the square of the lengthincrease. Growth was most rapid in January to April, slow in July to October. As a conservative estimate, the summer biomass of the various species of seaweeds had a turnover of 4 to 10 times in the course of 1 year. Applying these figures to an earlier survey of biomass, it is estimated that annual production of seaweeds in St. Margaret's Bay, Nova Scotia, Canada, amounts to 603 gC/m2 averaged over the whole bay, 1750 gC/m2 averaged over the sea-weed zone, or 648.000 gC/m of shore line. Approximate calorific equivalents are 6030 kcal/m2 over the whole bay, or 6480×103 kcal/m of shore line.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00348280
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  • 2
    Electronic Resource
    Electronic Resource
    Ecological energetics of the seaweed zone in a marine bay on the Atlantic coast of Canada. III. Energy transformations by sea urchins (1973)
    Springer
    Marine biology 18 (1973), S. 99-114 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An energy budget was constructed for a population of the sea urchin Strongylocentrotus droebachiensis in the nearshore area of St. Margaret's Bay, Nova Scotia, Canada. Of the 6 age classes identified, ages 1+and 2+accounted for about 1/2 the population energy flow. Population production efficiencies were: production/assimilation=0.28, production/consumption=0.04 to 0.13, and production/biomass=0.80. Although S. droebachiensis was the dominant herbivore in the seaweed bed, it utilized only 1 to 7% of seaweed production. As with other populations of sea urchins, however, it had a proportionately greater influence on seaweed biomass, and also presumably production, by clearing seaweed from large areas of substrate and maintaining it clear. Loss of dissolved organic matter, the only term in the energy budget not measured, was estimated by substracting the other terms in the energy budget from consumption. In laboratory individuals, this ranged from 40 to 80% of absorption (consumption-faeces). A critical review of energy budgets for 6 other species of marine benthic grazers also revealed large amounts of energy unaccounted for that might be attributed to loss of dissolved organic matter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00348685
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  • 3
    Electronic Resource
    Electronic Resource
    An annual carbon budget for the kelp Laminaria longicruris (1977)
    Springer
    Marine biology 44 (1977), S. 85-96 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Oxygen evolution and uptake by whole thalli of the large marine alga Laminaria longicruris de la Pylaie were measured for 24 h, once every 2 weeks for a year, using large chambers to incubate the plants on the sea bed. Diel rates of photosynthesis and respiration were calculated from these measurements and continuous light measurements were used to extrapolate the data between observation dates. The resulting estimates were combined with measurements of growth and carbon content to give an annual carbon budget for a typical mature plant. Annual net assimilation was 6.8 mgC per cm2 of frond surface (71 cal cm-2). Approximately 45% of this appeared in the production of new frond tissue, and a further 12% was accounted for by storage of carbon in mature frond tissue. About 8% was needed for stipe growth, and the remaining 35% was assumed to be lost as dissolved organic carbon. Diel net photosynthetic rates reached a maximum in June and July and were negative only in November, indicating an ability to produce a photosynthetic surplus throughout winter. In early winter the plants drew on stored reserves to supplement photosynthesis in providing carbon for growth, but from January onwards photosynthesis provided more than enough carbon for growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00386909
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  • 4
    Electronic Resource
    Electronic Resource
    Stable carbon isotope variability in marine macrophytes and its implications for food web studies (1984)
    Springer
    Marine biology 81 (1984), S. 223-230 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Stable carbon isotope ratios (δ13C) of eelgrass Zostera marina and of kelp Laminaria longicruris showed considerable variation in time and space. The isotopic composition of Z. marina varied seasonally from a mean of-6‰ for leaves formed in June to a mean of-10‰ for leaves formed in February. The maximum range for individual leaves was from-5 to-11.4‰. Once a leaf was fully formed, its isotopic composition appeared not to change. In L. longicruris there was no clear seasonal pattern of variation, but in any given blade there was a spatial pattern of variation, with the thickened central band tending to be least negative and the margins most negative. In one blade the range was from-12 to-20‰. Since this range overlaps values that are found in various other macrophytes and in seston, the value of the stable carbon isotope ratio as a tracer in food webs involving macroalgae is questioned. For Z. marina, in which the values are seasonally predictable, the technique may be useful if interpreted with care. The most probable explanation of variation in the ratios is differential storage of biochemical components of different isotopic compostion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393216
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  • 5
    Electronic Resource
    Electronic Resource
    The role of isopods and amphipods in the initial fragmentation of eelgrass detritus in Nova Scotia, Canada (1980)
    Springer
    Marine biology 59 (1980), S. 63-69 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Daytime observations on the isopods Idotea phosphorea and I. baltica and the amphipod Gammarus oceanicus held in laboratory microcosms showed that I. phosphorea and G. oceanicus spent 45% and 30% respectively, of their active time feeding on dead, intact eelgrass leaves which had been recently released from plants. I. baltica spent 41% of its active time consuming intact green leaves. The shredding of intact dead leaves by I. phosphorea and G. oceanicus resulted in production of small detrital particles which were liberated from the faeces of the invertebrates and this type of feeding led to the breakdown of whole leaves. Field experiments which separated the effects of shredding by invertebrates and grinding by waves and ice on the loss of weight from leaf packs showed that relative to controls isopods significantly increased weight loss from dead leaves. Loss of weight from leaf packs exposed to both biotic and physical shredding forces was not significantly different from that found on those exposed only to shredding by isopods. However, trends in the data indicated that fragmentation of whole, dead leaves in the field probably is a result of the synergistic effects of shredding by invertebrates and physical factors, particularly ice grinding. The role played by invertebrates in fragmenting intact, dead leaves is discussed in the light of energy flow and nutrient cycling within seagrass systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00396983
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  • 6
    Electronic Resource
    Electronic Resource
    Changing lobster abundance and the destruction of kelp beds by sea urchins (1976)
    Springer
    Marine biology 34 (1976), S. 137-142 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a study area in Nova Scotia, Canada, abundance of the lobster Homarus americanus decreased by nearly 50% in 14 years. The lobster is a major predator of sea urchins, and during the past 6 years the sea urchin Strongylocentrotus droebachiensis has destroyed 70% of the beds of Laminaria spp. in the area. Implications for management are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00390755
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  • 7
    Electronic Resource
    Electronic Resource
    The role of behavioral responses to predators in modifying urchins' (Strongylocentrotus droebachiensis) destructive grazing and seasonal foraging patterns (1981)
    Springer
    Marine biology 63 (1981), S. 39-49 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We documented spatial and temporal patterns of urchins (Strongylocentrotus droebachiensis) and periwinkles (Littorina littorea) in three habitats: a persistent Laminaria longicruris and L. digitata bed; an urchin dominated barrens, and the edge of the kelp bed that formed a boundary between the two. Urchins were rare in the kelp and, when present, always large and well hidden, a pattern we interpret as a response to crab and lobster predation. Urchins were abundant in the barrens, and, in the summer when predaceous fish were active during the day, foraged only at nigh. We observed the formation of a dense urchin feeding front along the kelp bed edge, and these urchins remained exposed and feeding even during the summer. Laboratory experiments demonstrated that aggregations are an effective defense against some predators, and that the presence of crabs increases the tendency of large urchins to aggregate. We hypothesize that healthy Laminaria spp. beds persist because kelp bed associated predators keep urchins at low densities and in hiding. A reduction in predation pressure permits urchin densities to increase to the point where they form aggregations, which provide better defense than hiding. These aggregations then graze destructively on Laminaria spp., forming barrens. These barrens seem to be a new, stable configuration of the system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00394661
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  • 8
    Electronic Resource
    Electronic Resource
    Ecological energetics of the seaweed zone in a marine bay on the Atlantic coast of Canada. I. Zonation and biomass of seaweeds (1972)
    Springer
    Marine biology 12 (1972), S. 1-10 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An intertidal and underwater survey of the zonation of seaweed in St. Margaret's Bay, NovaScotia, Canada showed 8 major zones as one proceeded away from shore: (1) Fucus and Ascophyllum; (2) Chorda with filamentous browns; (3) Chondrus crispus; (4) Zostera marina; (5) Laminaria digitata with L. longicrusis; (6) Laminaria longicruris; (7) L. longicruris with Agarum cribrosum; (8) Agarum cribrosum with Ptilota serrata. Zostera occurred at the same level as O. crispus but replaced it in sheltered water. Ascophyllum was more abundant in sheltered water. L. digitata was confined to the more exposed, steeper shore. The average horizontal extent of the seaweed zone was 369 m, and the greatest depth of significant amounts of seaweed 20 to 30 m. Laminaria longicruris contributed 36% of the total biomass, and Laminaria spp. and Agarum together constituted 83%, while intertidal seaweeds contributed less than 10% of the biomass. The estimated average total biomass per m of shore line was 1,481 kg fresh weight, 326 kg dry weight, 98 kg carbon, or 980x103 kcal. When averaged over the whole area of the bay, the corresponding figures were 1.38 kg/m2 fresh weight, 0.30 kg/m2 dry weight, 91 g/m2 carbon or 912 kcal/m2. Dry matter of Laminaria was 15 to 27% of fresh weight in blades, 10 to 12% in stipes. The dry matter content of blades was least in spring and highest in autumn, but carbon content and calorific value of dry matter showed little difference with species or season.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00347424
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  • 9
    Electronic Resource
    Electronic Resource
    Changes in sea urchin populations after the destruction of kelp beds (1976)
    Springer
    Marine biology 36 (1976), S. 321-326 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In St. Margaret's Bay, Nova Scotia, Canada, there are large areas in which sea urchins (Strongylocentrotus droebachiensis) have eliminated beds of kelp (Laminaria spp.). Sites were identified where destruction of kelp beds had taken place 1, 2, 3, 3.5 and 4 years ago. With increase of time since kelp disappearance, the sea urchins showed decreased growth rate, reduced gonad size, but an increase in numbers resulting from high recruitment rates in the first two years after kelp bed destruction. These sea urchin populations, by their browsing, effectively prevent the regeneration of kelp. There is, as yet, no evidence of the sea urchin populations being starved out to allow the kelp to return.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00389193
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  • 10
    Electronic Resource
    Electronic Resource
    Seasonal patterns of growth and storage in Laminaria longicruris in relation to differing patterns of availability of nitrogen in the water (1982)
    Springer
    Marine biology 69 (1982), S. 91-101 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The annual cycles of growth and of internal storage of nitrogen and carbon in Laminaria longicruris were compared at three sites in Nova Scotia, Canada. One site had abundant nitrogen all year round, on account of local upwelling, one had abundant nitrogen for only four months and the last was intermediate in this respect. Where nitrogen was abundant year round, growth followed the seasonal pattern of light, and there was little storage of either carbon or inorganic nitrogen. Where nitrogen was only abundant in the sea in winter, growth accelerated at this time and continued throught early summer while internal reserves of nitrogen were utilized. Carbon was stored in summer and used for growth in the fall. At the intermediate site, larger reserves of nitrogen were built up in winter and a high growth rate was maintained through most of the summer. Smaller carbon reserves were accumulated and growth was minimal in winter. Experiments in which plants were transplanted between sites were not conclusive, but suggested that plants at different sites may have genetic differences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00396965
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