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排序方式： 共有345条查询结果，搜索用时 78 毫秒
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Sebastiano Calvo Gianfranco Lovison Maria Pirrotta Germana Di Maida Agostino Tomasello & Mariangela Sciandra 《Marine Ecology》2006,27(4):361-371
The relationship between flowering and growth performance of Posidonia oceanica (L.) Delile in meadows distributed along the south‐eastern coast of Sicily (Italy) was investigated by means of a statistical model (generalized linear mixed model) combined with the lepidochronological analysis. Over a 28‐year period, 67 floral stalk remains were observed. The highest flowering index was recorded in lepidochronological year 1998 (10.1%) and the Inflorescence Frequency per age showed a clear decrease corresponding to 15‐year‐old shoots. The sexual reproductive event had positive effects on rhizome elongation (cm year?1) and leaf production (no. leaves year?1) in the same flowering year, whilst no effect on the rhizome production (mg year?1) was observed. Rhizome growth variables showed significant negative lagged responses in the two years following flowering. On the whole, we calculated that the effect exerted by flowering, in terms of loss on rhizome elongation and production, was about 27% and 38%, respectively. Although it has been demonstrated that recovery from the stress induced by sexual reproduction is limited to the two years after flowering, the magnitude of the reproductive cost may become quite considerable especially in comparison with the whole lifespan of individual shoots. 相似文献
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Regional variation in maturation of sandeels in the North Sea 总被引：1，自引：0，他引：1
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Biological Responses to Seasonally Varying Fluxes of Organic Matter to the Ocean Floor: A Review 总被引：8，自引：0，他引：8
Andrew J. Gooday 《Journal of Oceanography》2002,58(2):305-332
Deep-sea benthic ecosystems are sustained largely by organic matter settling from the euphotic zone. These fluxes usually
have a more or less well-defined seasonal component, often with two peaks, one in spring/early summer, the other later in
the year. Long time-series datasets suggest that inter-annual variability in the intensity, timing and composition of flux
maxima is normal. The settling material may form a deposit of “phytodetritus” on the deep-seafloor. These deposits, which
are most common in temperate and high latitude regions, particularly the North Atlantic, evoke a response by the benthic biota.
Much of our knowledge of these responses comes from a few time-series programmes, which suggest that the nature of the response
varies in different oceanographic settings. In particular, there are contrasts between seasonal processes in oligotrophic,
central oceanic areas and those along eutrophic continental margins. In the former, it is mainly “small organisms” (bacteria
and protozoans) that respond to pulsed inputs. Initial responses are biochemical (e.g. secretion of bacterial exoenzymes)
and any biomass increases are time lagged. Increased metabolic activity of small organisms probably leads to seasonal fluctuations
in sediment community oxygen consumption, reported mainly in the North Pacific. Metazoan meiofauna are generally less responsive
than protozoans (foraminifera), although seasonal increases in abundance and body size have been reported. Measurable population
responses by macrofauna and megafauna are less common and confined largely to continental margins. In addition, seasonally
synchronised reproduction and larval settlement occur in some larger animals, again mainly in continental margin settings.
Although seasonal benthic responses to pulsed food inputs are apparently widespread on the ocean floor, they are not ubiquitous.
Most deep-sea species are not seasonal breeders and there are probably large areas, particularly at abyssal depths, where
biological process rates are fairly uniform over time. As with other aspects of deep-sea ecology, temporal processes cannot
be encapsulated by a single paradigm. Further long time-series studies are needed to understand better the nature and extent
of seasonality in deep-sea benthic ecosystems.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Abstract. .The reproductive cycle of the brittlestar Ophioderma brevispinum is described using histological and organ index data for a population in Massachusetts, U.S.A. The cycle consists of a one month mid-summer spawning phase followed by gametogenesis and gradual gonadal growth during the winter, and greatly accelerated gonadal growth from May to June. At the end of the spawning season, oogonia proliferate near the base of the ovary, and a continuous layer of spermatogonia lines the testis. As oocytes grow to a maximum diameter of 350 um, yolk granules accumulate and the cytoplasm becomes less basophilic. Prior to spawning, the testis becomes branched and sulcate, and a whorl of spermatozoa produced by columns of spermatids accumulates in the lumen. Comparisons between the reproductive cycles of different populations of O. brevispinum and its congeners support the hypothesis that temperature may be a critical exogenous factor, but definitely not the only factor, in the initiation and duration of the growth and spawning phases of the ophiuroid reproductive cycle. 相似文献
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台湾海峡及其邻近海域中华哲水蚤的分布和繁殖 总被引：1，自引：0，他引：1
中华哲水蚤(Calanus sinicus Brodsky)是我国近海的优势桡足类。它的数量大，分布广。特别在冬、春季，在我国近海浮游动物中，占有相当大的比例；同时它的个体也较大，是滤食性种类。因其在海洋生态系统的物质循环和能量流动中，起着相当的作用，所以被国家自然科学基金重大项目-“东、黄海生态系统动力学与生物资源可持续利用”课题定为浮游动物的关键种之一。
作者根据以往历史资料(方金钏，1979；朱长寿，1997；朱长寿等，1991、1999；林玉辉等，1988；林元烧等，1984；李少菁，1963；陈清潮，1964；福建省海岸带和海凃综合调查领导小组，1990；福建海洋研究所，1988；Tan，1970)和多年来的研究结果(黄加祺等，1984，1986a、b、c，1989，1991a、b，1997a、b)，对中华哲水蚤在不同水域的分布，与温、盐度关系及繁殖进行了探讨，并提出见解，为本项目子课题提供了历史资料。 相似文献