共查询到20条相似文献，搜索用时 15 毫秒
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《Journal of Sea Research》2007,57(2-3):230-235
The live body mass, body volume, and length were determined for four groups of juvenile plaice (Pleuronectes platessa L.): (1) plaice immigrating into the Wadden Sea, (2) fish that had settled in the Wadden Sea, (3) settled fish that had been starved, and (4) laboratory-reared fish. Mass and volume values were obtained by applying Archimedes' principle to weights of fish obtained while they were immersed in waters of different densities. The allometric relationship of mass, volume, and length was determined for each group using principal component analysis. Fish in each treatment group had different mass-volume-length trajectories. Immigrating fish had the least mass and volume at fixed length, followed by settled fish, and laboratory-reared fish had the greatest mass at fixed length. Mass and volume differences between freshly captured settled fish and starved fish were slight. All treatments showed great variability in body mass and volume at fixed length, and the use of fish length alone as an index of fish size is problematic. It is suggested that centroid size is a better measurement of fish size when size is an important variate in a study. 相似文献
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Growth Dynamics in Posidonia oceanica (L.) Delile 总被引：1，自引：0，他引：1
Abstract. Amounts of photosynthate in the rhizomes, in photosynthetically inactive basal parts of the leaves and different old leaf blades were examined. Winter leaf growth was supported by mobilisation of starch in the rhizome. This winter growth enables Posidonia oceanica to utilize the increased energy influx in early spring via the substantial leaf area already developed and to approach highest productivity in spring. During summer and autumn considerable concentrations of soluble carbohydrates were found in the leaves and rhizomes. Starch was stored in the rhizomes in concentrations of up to 6.8 % of dry weight. Levels of nitrogen and free amino acids were correlated with growth rates. The percentage of total nitrogen present as free amino acid-nitrogen decreased from November (35 %) to summer (less than 1 %), by which time leaf growth had stopped. In contrast to this, amounts of organic anions were low in winter and spring and reached their maximum in summer.
Within a shoot, sites of leaf growth were characterized by high amounts of total nitrogen and free amino acids (innermost leaves), while carbon Fixation was highest in the leaves #2–#4. Particularly high concentrations of soluble carbohydrates were found midway along leaf blades.
It is evident that this unusual growth rhythm of Posidonia oceanica was only possible because of the ability to store considerable amounts of carbon and nitrogen in the rhizomes.
The results of this investigation demonstrate on the one hand that the chemical composition of the plant is strongly correlated with growth and production, and on the other hand that it is dependent on environmental factors, such as energy influx and temperature, which change with season. 相似文献
Within a shoot, sites of leaf growth were characterized by high amounts of total nitrogen and free amino acids (innermost leaves), while carbon Fixation was highest in the leaves #2–#4. Particularly high concentrations of soluble carbohydrates were found midway along leaf blades.
It is evident that this unusual growth rhythm of Posidonia oceanica was only possible because of the ability to store considerable amounts of carbon and nitrogen in the rhizomes.
The results of this investigation demonstrate on the one hand that the chemical composition of the plant is strongly correlated with growth and production, and on the other hand that it is dependent on environmental factors, such as energy influx and temperature, which change with season. 相似文献
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Jrg A. Ott 《Marine Ecology》1980,1(1):47-64
Abstract. In situ investigations of growth and production in a stand of Posidonia oceanica (L.) DELILE at a depth of 4 m at Ischia (Gulf of Naples) were carried out over two growing seasons. Posidonia starts to grow in August and an average bundle produces ten leaves in increasing time intervals until May. Growth curves for the leaves are given. Maximum leaf standing crop is in May with 1300 g dry weight per m-2, leaf area index at this time reaches 22 m2 m-2. Leaf net productivity is highest in March with 12 g dry weight per m2 per day. Annual leaf production is estimated as 3110 g dry weight per m2, “underground” production as 115 g dry weight per m2. About half the leaf production is exported from the system. Adaptive strategies of the growth and production pattern are discussed. 相似文献
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J. Aguzzi P. Puig J.B. Company 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(3):366-373
Data on biological rhythms of the Norway lobster Nephrops norvegicus (L.) are compared with new findings on inertial currents, a non-photic geophysical hydrodynamic fluctuation. Laboratory experiments on animal endogenous cardiac activity and locomotor rhythms using individuals from the middle slope (400–600 m depth) of the Mediterranean Sea revealed a consistent proportion of ultradian 18-h animals (20.6% and 12.0% of the studied cases for cardiac and locomotor tests, respectively). This characteristic, not reported in similar experiments with individuals from shallower depths (20–200 m) in the Atlantic Ocean, was initially considered meaningless from an ecological point of view. However, a close comparison with in situ oceanographic measurements over 1 year revealed a clear relationship between inertial current fluctuations and the observed 18-h behavioural and physiological rhythms. We propose a novel scenario involving potential non-photic (i.e. hydrodynamic) modulation of Nephrops biorhythms, and suggest that this may provide a paradigm for other benthic species in deep-water areas. 相似文献
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A. M. R. Burnet 《新西兰海洋与淡水研究杂志》2013,47(3):385-388
The recapture of tagged brown trout (Salmo trutta L.) in two experimental streams gave over 60% recapture in the section of stream where they were released, and over 80% when adjacent areas were included. Operation of a downstream trap showed that there was little emigration from the area above the trap and it is concluded that most of the fish which disappear die. 相似文献
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Trevor G. Dix 《新西兰海洋与淡水研究杂志》2013,47(2):363-374
Neopeltopsis pectinipes gen. et sp. nov. is described and figured from sublittoral marine algae at Wellington, New Zealand; the genus is an addition to the Peltidiidae Sars. The genus is compared with the other genera of the family, and a revised key is given to the genera of the Peltidiidae. 相似文献
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《Estuarine, Coastal and Shelf Science》1987,24(5):711-723
Umbonium vestiarium (L.) was found to dominate intertidal sand with a mean 11 808 m−2 (95·4 g tdw m−2), excluding virtually all other invertebrate fauna. Whilst spawning occurs from mid-March to August, substantial recruitment seems limited to March–May, first on the lowest levels, and then upshore as the young grow to 5–6 mm by June and as the growing young move upshore.The number of ovarian eggs varied in broad accordance with total tissue dry weight: both numbers of ovarian eggs and total dry weight in females and males increased in periods between bouts of spawning but fell during substantial spawning which was mostly close to neap tides. The relationships between planktonic-egg counts, ovarian-egg counts and tissue dry weight, together with direct weighings of ovarian eggs, suggest (a) mature eggs weigh about 2·5 μg each (dry weight), (b) 10-mm females each produced about 8800 eggs (22 mg) in the 79-day observation and probably 17 000–19 000 eggs (44 g) in the total spawning period (March–August), (c) the population as a whole produced about 30 × 106 eggs m−2 (75 g m−2) in the 79 days and probably around 60 × 106 eggs m−2 (150 g m−2) plus a similar quantity of semen in March–August, giving a total reproductive output of aproximately 300 g m−2 year−1.As Umbonium lives for only about one year with apparently one annual major period of spawning and recruitment, it is proposed that high reproductive output, large eggs and reduced larval dispersal may be adaptively related to the short lifespan on comparatively unstable and isolated habitats. These features are likely to have significant effects upon the genetic heterogeneity of Umbonium populations across its great Indo-West Pacific range. 相似文献