Nutrients, Chlorophyll a and Phytoplankton in the İskenderun Bay (Northeastern Mediterranean)     

Sevim Polat 《Marine Ecology》2002,23(2):115-126

Abstract. The monthly changes in chlorophyll a , phytoplankton abundance and nutrient concentrations at two stations, one at the inshore and the other at the deep waters of the northern part of İskenderun Bay, were investigated between 1994 – 1995. The vertical distribution of nutrients and phytoplankton biomass were also studied at the deep station. The concentrations of NO₃+NO₂-N, PO₄-P and SiO₄-Si of surface water at both stations were 0.31 – 1.63 µg-at · l^-1, 0.08 – 0.60 µg-at · l^-1 and 0.50 – 2.7 µg-at · l^-1, respectively. The highest concentrations were measured at the inshore station and clear differences were found between the inshore and deep-water stations. Chlorophyll a concentrations ranged from 0.17 to 2.78 µg · l^-1 and the highest value was measured in March. At the inshore station, which was affected by land run-off, phytoplankton abundance reached the highest value (21,308 cells · l^-1) in October 1995, with a marked dominance of Pseudonitzschia pungens (20,200 cells · l^-1). The nutrient and chlorophyll a concentrations at the inshore station were higher than those at the deep station. One reason for this is the land-based nutrient input into the coastal area here. In spite of these effects, the bay is not eutrophicated because of circulation events in the northeastern Mediterranean.  相似文献   

化合氯对浮游植物对绿素a和光合作用影响的室内研究     

韦桂峰  王肇鼎 《热带海洋学报》2001,20(2):47-53

化合氯是温排水中主要的化学物质,它的存在会对电厂邻近水域中生活的浮游植物造成一定的影响,运用均匀设计的实验方法研究温度,化合氯浓度,氯处理时间,及这3个因素之间的交互作用,从中筛选出影响叶绿素a含量与光合作用过程的主要因子,结果表明：影响叶绿素a的主要因子是氯处理时间,氯浓度与处理时间之间的交互作用（置信水平为99％）,影响光合作用的主要是氯处理时间,氯浓度,氯处理时间与氯浓度之间的交互作用,以及温度与氯处理时间的交互作用（置换水平为98％）。  相似文献   

Phytoplankton production in two east coast estuaries: Photosynthesis-light functions and patterns of carbon assimilation in Chesapeake and Delaware Bays     

Lawrence W. Harding  Jr  Blanche W. Meeson  Thomas R. Fisher  Jr 《Estuarine, Coastal and Shelf Science》1986,23(6)

Chesapeake Bay is a large and productive estuary that has received close scrutiny in recent years because of indications that its water quality and biota have been damaged by man's activities. Data on primary production for the estuary as a whole, however, are surprisingly sparse. We describe here the distribution of photosynthetic carbon assimilation by phytoplankton in Chesapeake Bay, and relate productivity patterns to hydrographic characteristics of the estuary. Between March 1982 and April 1983, a series of four cruises was conducted on Chesapeake Bay, and two cruises on the urbanized Delaware Bay for comparison. The upper Chesapeake and Delaware were highly turbid with high concentrations of suspended particulate matter and dissolved inorganic nutrients. Low chlorophyll concentrations were usually found in these areas of high turbidity, despite the abundance of nutrients, suggesting light limitation. Application of Wofsy's (1983) model of phytoplanton growth confirmed this suggestion. Chlorophyll and productivity maxima usually occurred seaward of the turbidity maxima where light penetration increased and suffient nutrients were present to support active phytoplankton growth. Further seaward of the chlorophyll maxima in the Chesapeake, the photic zone depth increased, concentrations of nutrients decreased, and phytoplankton biomass decreased, suggesting that nutrient availability, rather than light, controlled phytoplankton growth in the lower portion of the estuary. In contrast to the Chesapeake, Delaware Bay was more turbid, had generally higher nutrient concentrations, and was lower in phytoplankton productivity. The chlorophyll maxima and region of rapid phytoplankton growth occurred further toward the lower estuary and shelf regions in Delaware Bay because the high turbidity extended further seaward. Nutrients were never depleted at the shelf end of the estuary sufficiently to retard phytoplankton growth. Photosynthesis-irradiance (P-I) curves from simulated in situ and constant intensity incubations showed a strong correlation of the light-limited slope (a^B) with the light-saturated rate ( ) on each cruise. Spatial variations in corresponded to patterns of phytoplankton abundance, as did integral production (PP) and carbon-based growth rates (μ_C, μ_m), and photosynthetic parameters varied significantly with temperature.  相似文献   

Seasonal succession of cyanoprokaryotes in a hypereutrophic oligo-mesohaline lagoon from the South of France   总被引：2，自引：0，他引：2  

Nicolas Chomrat  Robert Garnier  Cline Bertrand  Arlette Cazaubon 《Estuarine, Coastal and Shelf Science》2007,72(4):591-602

The Bolmon lagoon (South of France) is an oligo-mesohaline coastal lagoon that has undergone intense eutrophication in the past decades, resulting from a strong concentration of human activities in its drainage basin. Consequently, it exhibits some characteristics typical of an advanced trophic state; namely, the disappearance of submerged vegetation, the permanently intense phytoplankton growth and the recurrence of cyanoprokaryote blooms. As cyanoprokaryote dominance in south-temperate saline lagoons is little reported, we carried out this study in order to understand the seasonal variations in the phytoplankton composition and biomass, and to analyse the influence of environmental parameters such as salinity, nutrients and climate on the seasonal succession of species. In this lagoon, the phytoplankton was permanently dominated by cyanoprokaryotes, probably because of high availability of nutrients, low light penetration in the water column and frequent turbulent mixing induced by wind. The two most abundant species Planktothrix agardhii (in winter–spring) and Pseudanabaena limnetica (in summer) have low light requirements and are well adapted to a high mixing frequency, which defines the S1 functional group in Reynolds' typology for phytoplankton. Although widely studied in north-temperate lakes, blooms of these typically freshwater species are almost unreported in the Mediterranean area, especially in brackish ecosystems that are not their normal habitat. In the Bolmon lagoon, all their requirements for nutrients, light and mixing are satisfied and they seem to cope with a moderate presence of salt but P. agardhii was less competitive than P. limnetica at highest salinities, the latter being probably more halophytic. Contrary to the observations in lakes located at higher latitudes, the Mediterranean climate seems to induce a typical seasonal pattern of succession characterised by the dominance of P. agardhii (winter) – Chroococcales (spring) – Pseudanabaenaceae (summer) – P. agardhii (autumn, winter). The warm temperatures seemed to have a major influence on the phytoplankton succession, being responsible for the survival of Planktothrix during winter and its rapid and intense development in early spring. Intense mixing and high irradiance in summer promoted the development of Pseudanabaenaceae, as reported in another south-temperate lagoon, the Albufera of Valencia (Spain). The ecological success of Oscillatoriales observed in the Bolmon lagoon is a perfect example of a shift to the “turbid stable state” as proposed for freshwater shallow lakes only. Our work demonstrated that hypereutrophic Mediterranean lagoons can function very similarly to shallow lakes at higher latitudes; but the warmer climate and higher irradiances are probably responsible for differences in the seasonal pattern of species dominance.  相似文献   

Consequences of winter upwelling events on biogeochemical and phytoplankton patterns in a western Galician ria (NW Iberian peninsula)   总被引：3，自引：0，他引：3  

Ricardo Prego  Dafne Guzmn-Zuiga  Manuel Varela  Maite deCastro  Moncho Gmez-Gesteira 《Estuarine, Coastal and Shelf Science》2007,73(3-4):409-422

The consequences of two upwelling events in mid- (MW) and late (LW) winter on biogeochemical and phytoplankton patterns were studied in the Pontevedra Ria and compared with the patterns measured under typical winter conditions and under a summer upwelling event. Thermohaline patterns measured during the mid-winter upwelling event (MW-up) revealed the intrusion of saltier seawater (35.9) into the ria associated with the Iberian Poleward Current (IPC). During the late-winter upwelling event (LW-up), the seawater which had welled up into the ria showed characteristics of the Eastern North Atlantic Central Water mass (ENACW). In both cases the measured water residence time (4 days during MW-up and 10 days during LW-up) was related to both meteorological and fluvial forcing. This residence time contrasts with that of summer upwelling (7 days) and with that estimated under unfavorable upwelling atmospheric conditions (2–4 weeks). During MW-up, the ria became poor in nutrients due to continental freshwater dilution, associated with the shorter residence time of the water, and the intrusion of IPC, which is a water body poor in nutrient salts: 2.9 μM of nitrate, 0.1 μM of phosphate and 1.5 μM of silicate. During this event, the ria exported 3.4 mol_DIN s⁻¹, compared with 6.9 mol_DIN s⁻¹ in non-upwelling conditions. Phytoplankton showed a uniform distribution throughout the ria, as during unfavorable upwelling conditions, and was characterized by the dominance of diatoms, mainly Nitzschia longissima and Skeletonema costatum. During LW-up, a nutrient depletion in the photic layer also occurred, but as a result of a phytoplankton spring bloom developing at this time. The ria was a nutrient trap where 4.1 mol_DIN s⁻¹ were processed by photosynthesis. This budget is three times higher than the one under non-upwelling conditions. In contrast with the MW-up, which had no effect on primary production, during LW-up the ria became more productive, although not as productive as during a summer upwelling event (9.9 mol_DIN s⁻¹). The taxonomic composition of the phytoplankton community did not change noticeably during LW-up and the summer upwelling, with the same species present and changing only in relative proportions. Diatoms were always the dominant microphytoplankton community, with Pseudonitzschia pungens, Thalassionema nitzschioides and several species of Chaetoceros as characteristic taxons.  相似文献   

Laboratory Culture and Preliminary Characterization of the Nitrogen-Fixing Rhizosolenia-Richelia Symbiosis     

Tracy A.  Villareal 《Marine Ecology》1990,11(2):117-132

Abstract. The oceanic diatom Rhizosolenia clevei and its cyanobactcrial symbiont Richelia intracel-luluris were isolated into laboratory culture and their biology and growth dynamics examined. Nitrogen-fixation by the symbiont could sustain the symbiosis. Growth and nitrogenase activity demonstrated light saturation kinetics, with no photoinhibition up to 315 μE m^-1 s^-1 for growth and 780μE m^-1 s^-1 for nitrogen fixation. The symbiosis is not obligate for Rhizosolenia , which is capable of growth independent of the symbiont if a nitrogen source is available. The symbiont is contained in the pcriplasmic space between the Rhizosolenia plasmalcmma and frustulc, and preliminary evidence suggests excretion of fixed nitrogen into the medium may be occurring.  相似文献   

渤海生态动力过程的模型研究 Ⅱ.营养盐以及叶绿素a的季节变化          下载免费PDF全文

刘浩  尹宝树 《海洋学报》2007,29(4):20-33

利用在本系列研究第一部分中所建立的耦合的生物物理模型,模拟了渤海浮游植物生物量和营养盐含量的年度循环特征.模拟结果显示:藻类的春季水华是由经过一冬积累在水体中的营养盐导致,而水华开始的时间在浅水区明显早于深水区,对此深水区水体层化结构的形成可能起着重要作用;另一方面,河载营养盐与悬起的沉积物所释放的营养盐是诱发夏季水华的共同原因.基于模型结果,我们还发现:渤海的浮游植物动力特性就整体而言依然受无机氮限制,但是在莱州湾,磷限制特性表现得非常明显,这主要是由于每年黄河都要携带大量的无机氮进入海水,从而导致莱州湾营养盐的氮磷比已远远超过16.  相似文献   

Microzooplankton production in the oceans   总被引：7，自引：0，他引：7  

Landry  Michael R.; Calbet  Albert 《ICES Journal of Marine Science》2004,61(4):501-507

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Nutrient budgets and trophic state in a hypersaline coastal lagoon: Lagoa de Araruama, Brazil     

Marcelo F. L. Souza  Bjrn Kjerfve  Bastiaan Knoppers  Weber F. Landim de Souza  Raimundo N. Damasceno 《Estuarine, Coastal and Shelf Science》2003,57(5-6):843-858

Lagoa de Araruama in the state of Rio de Janeiro, Brazil, is a hypersaline lagoon with salinity varying spatially from 45 to 56. We collected water samples during monthly cruises throughout the lagoon, and along the streams feeding the system, from April 1991 to March 1992. Nutrients and other water quality parameters exhibited great spatial and temporal variations. Mass balance calculations indicate large amounts of anthropogenic nutrient inputs. The data indicate that the lagoon currently is oligotrophic but is in a state of transition to become a mesotrophic system. Molar dissolved inorganic nitrogen:dissolved inorganic phosphorus (DIN/DIP) varied between 2.2:1 and 659:1 with a volume-weighted average of 22:1. The high DIN/DIP ratio contrasts with that found in nearby lagoons, suggesting that phytoplankton primary production is limited by phosphorus in Lagoa de Araruama. The major loss of DIP is apparently driven by biological assimilation and diagenic reactions in the sediments. Calculations indicate that the lagoon is slightly net autotrophic at +0.9 mol C m⁻² yr⁻¹. This suggests that the biomass of the primary producers is restricted by phosphorus availability. Phosphorus retention in the sediment and the hypersaline state of the lagoon prevent changes in autotrophic communities and the formation of eutrophic conditions.  相似文献   

长江口羽状锋海区浮游植物的生态研究：—昼夜分布动态   总被引：5，自引：0，他引：5  

杨蕉文  顾新根 《海洋学研究》1994,12(1):47-57

本文对长江口羽状锋海区浮游植物的昼夜变动进行了初步研究，结果表明，浮游植物数量的昼夜变化明显，潮汐作用是影响数量昼夜分布变化的主导因素，同时也与该地区浮游植物的水平分布有着密切的联系。  相似文献