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991.
Summer algal blooms in a coastal ecosystem: the role of atmospheric deposition versus entrainment fluxes 总被引:2,自引:1,他引:2
Jacob Carstensen Lise Marie Frohn Charlotte Bay Hasager Bo G. Gustafsson 《Estuarine, Coastal and Shelf Science》2005,62(4):595-608
The nitrogen inputs from atmospheric deposition and bottom water entrainment to the surface layer were modelled in the summer period (May–September) over a 11-year period (1989–1999) and compared to investigate the significance of these fluxes for generating blooms in the Kattegat. In the summer periods the average atmospheric deposition was 2.81 mg N m−2 d−1 compared to average entrainment fluxes of 5.42 mg N m−2 d−1, 1.21 mg N m−2 d−1 and 1.15 mg N m−2 d−1 for the northern, central and southern part of the Kattegat, respectively. Atmospheric nitrogen deposition alone could not sustain biomass increases associated with observed blooms and entrainment fluxes dominated the high nitrogen inputs to the surface layer. The potential for a bloom through growth was typically obtained after several days of high nitrogen inputs from entrainment in the frontal area of the northern Kattegat and to some extent from atmospheric deposition. The modelled nitrogen input in this area could account directly for 30% of the observed blooms in the Northern sub-basin, and through advective transport 24% and 19% of the observed blooms in the central and southern Kattegat. The direct nitrogen inputs through atmospheric deposition and entrainment to the central and southern sub-basins were small and could not be linked to any bloom observation. 相似文献
992.
Won Je Lee Kyoungsoon Shin Pung-Guk Jang Min-Chul Jang Nam Joo Park 《Ocean Science Journal》2005,40(3):1-9
Daily changes in phytoplankton abundance and species composition were monitored from July to September 2003 (n=47) to understand
which factors control the abundance at a station in Jangmok Bay. During the study, the phytoplankton community was mainly
composed of small cell diatoms and dinoflagellates, and the dominant genera wereChaetoceros,Nitzschia, Skeletonema andThalassionema. Phytoplankton abundance varied significantly from 6.40x104 to 1.22x107 cells/l. The initially high level of phytoplankton abundance was dominated by diatoms, but replacement by dinoflagellates
started when the N/P ratio decreased to < 5.0. On the basis of the N/P and Si/N ratios, the sampling period could be divided
into two: an inorganic silicate limitation period (ISLP, 14th July-12th of August) and an inorganic nitrogen limitation period (INLP, 13th of August - the end of the study). Phosphate might not limit the growth of phytoplankton assemblages in the bay during the
study period. This study suggests that phytoplankton abundance and species composition might be affected by the concentrations
of inorganic nutrients (N and Si), and provides baseline information for further studies on plankton dynamics in Jangmok Bay. 相似文献
993.
994.
B.T. Hargrave G.L. Bugden E.J.H. Head B. Petrie G.A. Phillips D.V. Subba Rao P.A. Yeats 《Estuarine, Coastal and Shelf Science》2007,73(3-4):379-398
Seasonal patterns of vertical flux over two years (2001–2003) at two stations in the Bras d'Or Lakes, a large estuary in Cape Breton Island, Nova Scotia, were determined using aluminum and organic carbon in settled particles collected in moored traps to calculate lithogenic (terrigenous) and marine biogenic fractions. On an annual basis, lithogenic material comprised 53% and 81% of dry weight and 48% and 66% of organic carbon in settled particles at the deep- (128 m) and shallow-water (41 m) locations, respectively. Peaks in runoff, inferred from rain and snowfall precipitation, ice cover and possible horizontal transport of resuspended sediment coincided with maximum sedimentation rates of lithogenic material during unstratified periods between October and March. Biological factors correlated with phytoplankton and ice algal primary production and seasonal changes in zooplankton grazing inferred from phaeopigments controlled biogenic particle fluxes under stratified conditions between June and September and during winter. Year-to-year variations in deposition of lithogenic and marine biogenic material depended on seasonal differences in stratification, precipitation, freeze/melt conditions and the extent of ice cover. 相似文献
995.
996.
紧密角管藻的有性生殖研究 总被引:3,自引:1,他引:3
1994年7月在厦门近岸分离紧密度管藻,培养研究有性生殖过程和氮营养、光条件对生殖的影响。结果显示,该藻卵配生殖中,复大孢子形成后,在经里面形成一个休眠孢子,然后休眠孢子再发育成大型的原初细胞。氮营养丰富时,只有小型细胞能够性化,并且只产生雄配子,氮营养贫乏可以诱导中型细胞同时产生雌雄配子。每天12h光照和11μEin(s.m^2)光强度最有地性化。研究结果表明,紧密角管藻有性周期中形成休眠孢子是 相似文献
997.
Soil core samples fromRhizophora mangleL. andAvicennia schauerianaStapf & Leech forests from south-eastern Brazil were analysed for their total organic matter content and their sugars, amino acid and amino sugars composition. Organic carbon and nitrogen contents were higher inAvicenniathan inRhizophorasoils. The contribution of sugars and amino acids to the total organic carbon pool was constant with depth inRhizophorasoils whereas inAvicenniasoils it increased. Spectral distribution of sugars and amino acids showed a dominance of Ca-affine monomers, particularly acidic amino acids, and the sugar arabinose. Biogeochemical indicators derived from ratios of individual sugar and amino acid monomers confirm previous studies which showed that organic matter in both soils is mainly of mangrove origin. The results further suggest accumulation of organic matter inRhizophorasoils and a continuing degradation of organic matter inAvicenniasoils. The latter may thus release more nutrients to adjacent ecosystems thanRhizophorasoils. 相似文献
998.
999.
胶州湾氮、磷浓度的三维数值模拟 总被引:1,自引:0,他引:1
考虑了近岸海域影响氮、磷含量、时空分布的主要物理、生物化学过程,建立了胶州湾海域非保守物质(氮、磷)的水质预测模型。模型将氮、磷及与其相关的浮游植物、浮游动物作为状态变量,模拟了胶州湾海域夏季各状态变量浓度的时空分布。结果表明胶州湾北部氮、磷浓度最高,湾中央及湾口海域水质较好,各变量垂向分布均匀。数值模拟结果与监测结果及历史资料较为符合。 相似文献
1000.
Abstract-The carbon and nitrogen budgets were estimated on the adult females, juveniles and post-furcilia larvae of Pseudeuphausia sinica fed on newly hatching nauplii of Artemia salina in the laborato-ry. It was found that the ingestion rate was linearly related to the food concentration, suggesting highfeeding potential. The linear correlation could be established between the respirating rate (carbon con-sumption rate) and carbon ingestion rate, as well as carbon assimilation rate. The regression coefficients(i.e.specific dynamic action coefficients) were in the range from 9% to 16% (ingested C) or 10% to17% (assimilated C) respectively, with lower in the post-furcilia larvae. There also existed a linearcorrelation equation between estimated total nitrogen excretion rate and the rates of nitrogen ingestionand assimilation separately, except for the juveniles. The defecation rates increased with the increase ofthe ingestion rate; as a result, assimilation efficiency was not related to the ingestion rat 相似文献