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1.
Microbial Biomass Dynamics Along a Trophic Gradient at the Atlantic Barrier Reef off Belize (Central America) 总被引：2，自引：0，他引：2
Abstract. Recent findings indicate that heterotrophic bacteria and not phytoplankton are the most numerous biomass components even in the euphotic zone of oligotrophic, open oceans. In this study it was hypothesized that the microbial biomass components change within a few hundred meters as oligotrophic water flows across the reef and becomes enriched with nutrients. Along a trophic gradient, four stations at the Atlantic Barrier Reef off Belize (Central America) were sampled for microbial biomass components. Phytoplankton biomass (measured as chlorophyll a) ranged from the most oligotrophic station (St. 1) to the most eutrophic station (St. 4) from 6.9–415.5 μg CI"' (assuming a C:chl a ratio of 30): heterotrophic bacterial biomass increased 4-fold (from 10.1–46.4μg C 1-1 ), heterotrophic nanoflagellate (HNAN) biomass increased from 4.6-19ug C 1-1 , and cyanobacteria from 0.9-4.5 μg C-1-1 . Production estimates derived from seawater cultures revealed a 5-fold increase in bacterial production from the oligotrophic station (3.7 ug C 1-1 d-1 ) to the eutrophic St. 4 (17.8ug C-1-d1-1 )- Cyanobacterial production rose from 1.1–3.5ug C-1–d-1 and HNAN production from 0.65-1.13 μg C-1-1 -d-1 . While cyanobacteria contributed between 13 and 20% to the autotrophic plankton component in the oligotrophic waters, their contribution dropped to about 1 % at the eutrophic stations. 相似文献
2.
Description of the Phytoplanktonic Community of the Oligotrophic Waters of the SE Aegean Sea (Mediterranean) 总被引：2，自引：0，他引：2
Abstract. A seasonal sampling program of five stations off the Island of Rhodes (SE Aegean Sea) was carried out in 1983–1984. Temperature, salinity, Secchi disk transparency, P-PO4 , N-NO3 , N-NO2 , N-NH3 , Si-SiO2 , and chl a were measured and phytoplankton species recorded. Cell concentrations and chl a varied seasonally. with the highest values in summer (l.2 times 104 -1- -1 total mean cells; 0.13 mgam-3 total mean chl a ) and the lowest in winter (2.3 times 103 , 1- -1 total mean cells; 0.06 mg. m-- total mean chl a ). A variation in cell abundance among stations was also noted. Quantitative relationships among the recorded taxa showed that diatoms and dinoflagellates were richer in species composition (88 and 58 total species, respectively) than coccolithophores (8 species) and other flagellates (8 species). Comparison of phytoplankton samples from different depths and stations by cluster analysis showed an irregularity or discontinuity in species associations. The SE Aegean Sea was characterized as oligotrophic on the basis of the estimated nutrient and phytoplankton concentration levels. 相似文献
3.
Abstract. Nitzschia sicula (C astr .) H ust ., a planktonic pennate diatom, dominated the microphytoplankton (104 -5 times 104 cells. 1-1 ) in the central, oligotrophic Southern Adriatic Pit waters (20-50m layer) in May 1990. Nauplii dominated the microzooplankton (3 indiv. 1-1 in the 0-50m layer, 130 μm mean body length) and produced a considerable amount of faecal (mini)pellets (1900. 1-1 at 50m, mean diameter 47μm), which were compactly filled with N. sicula frustules. The subsurface accumulation of diatoms and nauplii was probably the result of both productive activity under specific hydrographic conditions and the convergence in a relatively strong southern Adriatic cyclonic gyre; the advective transport of populations along the shear zone, at the boundary between water masses of different thermo-haline characteristics may also have played a role. The amount of minipellets was high if compared with the data available from other seas. This was probably due to high production of minipellets, their slow sinking rate, and/or an absence of manipulation of the faecal material by zooplankton. 相似文献
4.
Abstract. Thirteen sampling cruises were conducted at weekly intervals in the inner part of the Gulf of Naples in the summer of 1983 to investigate the effects of excess nutrient inputs on phytoplankton communities. High surface phytoplankton concentrations (up to 1.15 ×108 cells 1-1 ) were recorded, particularly near Naples harbour and along the eastern coast, two locations that receive most of the area's sewage and industrial discharge. Phytoplankton populations were generally dominated by small species, mainly diatoms, which were associated with small phytoflagcllatcs. Species diversity values were relatively high (H'≤ 3.62) in most samples. Throughout the sampling period a high spatial and temporal variability for phytoplankton abundances and species composition was observed. 相似文献
5.
Abstract. Coastal Patagonian sea waters had been differentially nutrient-enriched to determine (i) the magnitude of the algal biomass supported and (ii) which species were able to best compete for the available nutrients. Nitrogen was found to be the nutrient limiting growth of the natural phytoplankton population. The addition of NO3 at 25 μg at 1-1 led to a 10 to 30 μg 1-1 increase in chlorophyll a in all but those treatments containing trace metal additions. The best yield coefficients were obtained when a chelator (EDTA) was added with NO3 . A pool of nine diatom species were common in the N03 supplemented waters and the addition of vitamins along with NO3 allowed two of the nine species to dominate. 相似文献
6.
Abstract. seasonal sampling of three stations in Gulbahce Bay Aegean Sea for the zoobenthic organisms associated with a Zostera marina bed was carried out during 1993–94. Temperature, salinity and oxygen were recorded each sampling period. A total of 7 taxonomic groups were determined: Polychaeta was the dominant group comprising 77 % of the total taxa and individuals, followed by Crustacea, Bivalvia and other groups such as Nemertea. Sipuncula, Turbellaria and Phoronida. Of the 108 taxa encountered, the polychaetes Notomastus latericeus and Caulleriella alata accounted for 49 % of the total populations. The species abundance did not show major changes among seasons, with highest values in fall 982 indiv. ·m-2 and lowest in spring 754 indiv. ·m-2 . Diversity and evenness of the samples were relatively high and fairly constant, and were affected by the dominance levels of the species. 相似文献
7.
Response of Summer Phytoplankton to Episodic Meteorological Events (Gulf of Trieste, Adriatic Sea) 总被引：2，自引：0，他引：2
Abstract. Despite increasing evidence that atmospheric deposition may contribute considerably to new production in coastal seas, the role of this nutrient source in the shallow northern Adriatic ecosystem has remained largely unassessed. This study demonstrates that locally collected rain water significantly stimulates primary production and phytoplankton biomass accumulation in microcosm experiments. The concentration of nutrients in rain water collected during summer storms (11.38–77.19 μmol·1-1 nitrate. 4.45–36.38 μmol.1·1 ammonium, 0.93–4.75 μmol·1-1 phosphate) indicated that the precipitation is influenced by anthropogenic emissions from urbanised and industrialised regions of the European continent. Rainfall events delivered relatively large (127 tons nitrogen, 9.5 tons phosphorus in the period 10 June to 10 September, 1993). though episodic, nutrient input into the area. Field measurements showed that storm events were followed by an increase of phytoplankton standing crop and a shift of community structure. 相似文献
8.
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
9.
Abstract. Several species of cyanobacteria, diatoms and one euglenid alga populated the littoral zone of hypersaline solar ponds investigated over a period of three years. The composition of the microalgae community changed with salinity and temperature. In the shallow marginal zone the diatoms predominated in winter and spring, at salinities of 30–72 g-1-1 and at temperatures not exceeding 30o°C, whereas in summer, cyanobacteria were the most abundant. In the deeper zone, at higher salinities and temperatures, cyanobacteria predominated throughout the year. The depth limit of algal growth was 60-80cm, where salinity and temperature exceeded 211 g-1-1 and 48°C.
The most euryhaline and eurythermal among cyanobacteria were Aphanolhece halophytica F remy and Phormidium hypolimneticum C ampbell , among diatoms Nitzschia sp. aff. N. rostellata H ustedt , Amphora coffeaeformis (A gardh ) K utzing , and Navicula massadaea E hrlich . 相似文献
The most euryhaline and eurythermal among cyanobacteria were Aphanolhece halophytica F remy and Phormidium hypolimneticum C ampbell , among diatoms Nitzschia sp. aff. N. rostellata H ustedt , Amphora coffeaeformis (A gardh ) K utzing , and Navicula massadaea E hrlich . 相似文献
10.
Role of Bacteria in the Carbon and Nitrogen Flow between Water-Column and Sediment in a Shallow Marine Bay (Bay of Piran, Northern Adriatic Sea) 总被引：2，自引：0，他引：2
Abstract. The interdependences between phytoplankton standing crop, bacterial biomass and the dissolved organic matter (DOM) pool in the water column were investigated and related to sediment parameters in a shallow marine bay (Bay of Piran, Northern Adriatic Sea) over an annual cycle. Bacterioplankton density varied between 1–10 × 105 cells ml-1 , with lowest density observed in March corresponding to the low Chi a concentrations during this period. Generation times as determined by dialysis incubations ranged between 4h (June) and 82 h (March). Mean bacterial secondary production rates during summer were about 40 mg C m-1 d-1 and 5mg C m-3. d-1 during winter. With a short time lag, DOM concentrations followed the fluctuation in Chi a.
Sediment oxygen demand measurements revealed a mean mineralization rate of about 260 mg C m-2 d-1 during summer and 100–200 mg C m-2 d-1 in winter. Sediment bacterial density varied between 108 - 109 cells g (sediment dry wt)-1 in the top 5 cm sediment layer or, in terms of biomass, 4.3 g C m-l during summer and 0.6 g C m-2 during winter. Highest concentrations of DOM in pore waters were measured in September, coinciding with high rates of sediment oxygen demand. 相似文献
Sediment oxygen demand measurements revealed a mean mineralization rate of about 260 mg C m
11.
Abstract. The influence of corallivores on coral community structure of eastern Pacific reefs has been considered less important then that of abiotic oceanographic factors. The data that support this assumption, however, are only available for Central American reefs. To assess the role of predation on hermatypic corals in a different regional reef environment, the abundance, spatial distribution and consumption rate of three corallivores: the echinoid Eucidaris thouarsii (Valenciennes), the asteroid Acanthaster planci (Linnaeus) and the teleostean fish Arothron meleagris (Bloch & Schneider), were estimated at Cabo Pulmo reef, Gulf of California, México (23°25' N, 109°25' W). Statistically, the abundances of the species did not change in any sections of the reef (mean values: E. thouarsii , 0.17 indiv. · m−2 ; A. planci , 1.9 indiv. · m−2 ; A. meleagris , 39 indiv. · ha−1 ). The average daily individual consumption rates of coral were calculated at 1.83 g CaCO3 · m−2 for E. thouarsii , 118.4 cm2 for A. planci , and 16.38 g CaCO3 · m−2 for A. meleagris , and were lower than those reported for Central American reefs. Considering the mean estimated carbonate production (7.9 kg CaCO3 · m−2 · a−1 ), corallivores eliminate less than 4% of the coral standing stock of Cabo Pulmo reef. The low corallivore population density and consumption rates, together with high local coral cover, indicate that corallivores are not key factors determining scleractinian abundance in this marginal reef. 相似文献
12.
Abstract. Phytoplankton biomass estimators – total cell number (CN), total cell volume (CV), chlorophyll a (Chl a ). phytoplankton organic carbon (PC), and their response to environmental variables, with a special emphasis on the vertical variability in the structure of the water column – were examined in the Mali Ston Bay (Southern Adriatic). Correlations among biomass estimators as well as with physical-chemical parameters varied according to hydrodynamic characteristics of the water column. The amount of Chl a per cell ranged from 0.28.06–10-6 μg during stratification to 0.7–2.0.10-6 μg during the mixing period. Most frequent values for PC/Chl a ratios and for Chl a /CV in mixed natural phytoplankton populations were 20–25 and 1–2, respectively. 相似文献
13.
根据2015年春季南海北部陆架海域的调查数据,分析了网采浮游植物群落结构特征及其与环境因子的关系。结果显示:共鉴定出浮游植物4门378种(含变种与变型),其中硅藻门209种,甲藻门157种,蓝藻门9种,着色鞭毛藻门3种。该海区的主要优势种有翼鼻状藻Proboscia alata、翼鼻状藻纤细变型Proboscia alata f. gracillima、佛氏海毛藻Thalassiothrix frauenfeldii、尖刺拟菱形藻Pseudo-nitzschia pungens、短角弯角藻Eucompia zoodiacus和洛氏角毛藻Chaetoceros lorenzianus等,各断面优势种差异较大,仅佛氏海毛藻在4个断面成为优势种。浮游植物丰度范围为(0.63~1 430.04)×104个/m3,平均为76.20×104个/m3,丰度较高的站点主要集中在湛江断面D近岸站位和汕头断面H。春季南海北部浮游植物Shannon-Wiener多样性指数为1.06~5.56,均值为3.99。冗余分析显示,影响南海北部陆架海域浮游植物群落结构的主要环境因子为水温、盐度和活性磷酸盐。南海北部陆架海域浮游植物基本呈现近岸高离岸低的分布特点,水温和盐度是影响其分布的主要环境因子。 相似文献
14.
Abstract. Annual growth rates of gorgonians in the Indo-Pacific region are reported ror the first tinie. A method of measuring gorgonian growth using periodic photographic monitoring that is sensitive to horizontal growth and changes in growth foci but that does not require tedious underwater measurements is applied. Growth parameters of five species of gorgonians from three Families ( Plexauridae. Melithaeidae . and Subergorgiidae ) were monitored over a period of 18 months using this method. Growth rates ranged from 2.30 cm a-1 to 7.88 cm. a -1 in the highly sedimented waters of Singapore. The maximum number of branches added per year ranged from 1.7 to 14.5. 相似文献
15.
The use of taxonomic distinctness indices in assessing patterns of biodiversity in modular organisms 总被引：1，自引：0，他引：1
Stanislao Bevilacqua Simonetta Fraschetti Antonio Terlizzi & Ferdinando Boero 《Marine Ecology》2009,30(2):151-163
Estimating diversity of modular organisms may be problematic due to actual difficulties in discriminating between 'individuals' and quantifying their abundances. Quantitative data, when available, are collected through methods that could preclude the application of classical diversity indices, making comparisons among studies difficult. Taxonomic distinctness indices, such as the 'Average Taxonomic Distinctness' (Δ+ ) and the 'Variation in Taxonomic Distinctness' (Λ+ ) may represent suitable tools in investigating diversity beyond the simple species number. The potential usefulness of such indices has been explored almost exclusively on unitary organisms, neglecting modular ones. In this study, we employed Δ+ and Λ+ to analyse patterns of diversity of epiphytic hydroid assemblages living on Cystoseira seaweeds at a hierarchy of spatial scales, along 800 km of rocky coast (SE Italy). ANOVA on species richness and Λ+ showed no significant difference in sample diversity at the investigated spatial scales. In contrast, there were significant differences at the scale of 10s of km in Δ+ . Analyses based on simulations detected significant variations at all spatial scales in Δ+ . Such findings underline the potential of Δ+ in highlighting relevant spatial scales of variation in patterns of hydroid diversity. Our results also suggest that the interplay between natural environmental variations and the complex ecological traits of modular organisms might affect taxonomic distinctness indices. We stress the need for further investigations focusing on modular organisms before any generalizations on the use of taxonomic relatedness measures in examining marine biodiversity can be made. 相似文献
16.
Distribution pattern of zooplankton in the han river estuary with respect to tidal cycle 总被引：1，自引：0，他引：1
The monthly distribution of zooplankton communities in Han River estuary was investigated at two stations from July 1998 to
June 1999. Monthly mean abundance of total zooplankton varied remarkably, with the range from 20 indiv.·m-3 to 19,600 indiv.·m-3. During the study period, dominant species of zooplankton community were dinoflagellateNoctiluca scintillans, copepodsParacalanus indicus, Paracaanus crassirostris, Acartia hongi, Acartia ohtsukai, and meroplanton cirriped larvae. According to tidal states, relative high abundance occurred at high tide without regard
to season. The temporal distribution of abundance implied that the reduced salinity probably limited the zooplankton populations
and the fluctuations of salinity were an important factor in the variation of abundance. However, the results of salinity
tolerance test shows that the variations in salinity do not directly influence the decrease of abundance. This study shows
that the relatively high abundance of zooplankton near high tide seems to be related with the expansion of abundant zooplankton
inhabiting Incheon coastal waters through tidal currents. 相似文献
17.
旅游业为海岛带来可观经济效益的同时, 人类活动也导致水体生态环境恶化, 如水体富营养化加剧、赤潮频发等。文章通过对珠江口东南部典型海岛——庙湾岛和外伶仃岛周边水域丰水期和枯水期现场环境数据与浮游植物分布特征的对比研究, 分析珠江径流等自然因素以及人类活动对河口天然海岛周边水体生态的潜在影响。枯水期外伶仃岛和庙湾岛周边水域海水分别镜检鉴定出76种和74种浮游植物, 两个海岛浮游植物平均细胞密度分别为2.62×104个·L-1和2.08×104个·L-1; 丰水期则分别鉴定出38种和47种浮游植物, 平均细胞密度分别为52.91×104个·L-1和170.57× 104个·L-1。在外伶仃岛和庙湾岛, 丰水期中肋骨条藻(Skeletonema coatatum)均为绝对优势种, 而枯水期两个岛的最主要优势种分别为窄隙角毛藻(Chaetoceros affinis)和新月筒柱藻(Cylindrotheca closterium), 物种多样性指数均明显高于丰水期。两个海岛微型浮游植物相对于其他两个粒级常占据优势地位, 但在丰水期, 小型浮游植物贡献明显上升, 其中外伶仃岛相对于枯水期由16.32%升至26.75%, 庙湾岛则由12.12%升高至24.78%。两个海岛在丰水期和枯水期均仅检出聚球藻(Synechococcus, Syn)和真核微微型藻类(eukaryotic, Euk)两大微微型浮游植物类群, 两者细胞密度分别为~107个·L-1及~108个·L-1量级。与环境因子的对比分析表明, 两个海岛浮游植物的区域分布与季节变化受多种因素影响, 其季节性差异主要受径流影响强度、影响范围以及相应的盐度、营养盐等环境因素的季节变化所调控。丰水期岛屿屏蔽效应对浮游植物丰度的区域分布特征有显著影响, 无论小型浮游植物还是微微型浮游植物均发现存在迎流面出现丰度高值分布的现象, 但对群落结构的分布影响不明显; 在枯水期, 水体环境很可能主要受人类活动与水体垂直混合扰动的综合影响, 总体上浮游植物分布的区域差异较小。 相似文献
18.
Donat Petricioli Tatjana Bakran-Petricioli Damir Vili&#;i&#; Antonieta Po&#;ar-Domac 《Marine Ecology》1996,17(1-3):373-382
Abstract. In late summer and early autumn of 1989 benthic mortality in the upper part of Krka estuary extended from the Skradinski buk waterfalls to approximately 5 km downstream. Dead benthic organisms were found on the bottom at depths of up to 4.5 m. During August, a freshwater phytoplankton bloom was recorded in Visovac lake (which supplies the Skradinski buk waterfalls). The green tide in the lake was composed of up to 11.9 million cells. 1- -1 , predominantly of Synedra acus and Dinobtyon sertularia . At that time the maximal total inflow of phytoplankton cells through the waterfalls was approx. 0.41 S-I (38000 1. d-1 ). Cells of these two species died after reaching the salt wedge and the cummulative effect of their decomposition apparently caused an oxygen demand sufficient enough to trigger the benthic mortality. Due to the water mass dynamics, the spreading of mortality downstream was slow (from August to October, approx. 5 km). Certain benthic fishes (like Gobius sp.) were observed on the bottom of the affected area in mid-October 1989. 相似文献
19.
Abstract. A mixed population of unicellular and colonial cyanobacteria was transferred into culture from a hypersaline helio-thermal pond in the vicinity of the Dead Sea. The entire complex of strains, incubated in Dead Sea water of varying salinity and temperature, showed a pronounced shift of the maximal growth from a salinity of 72 g l-1 at 30 o C up to 142 g 1-1 at 50 o C. Over the above range of salinities and temperatures, these cyanobacteria were capable of about four divisions per day, providing that any increase in salinity was coupled with the suitable increase in temperature. The above peculiar adaptation can explain the prominent success of this group of microorganisms in the extreme and unstable ecological conditions of hypersaline habitats. Amounts of slime accumulating in the cultures were proportional to the incubation temperature. 相似文献
20.
Abstract. In the water-column of the Gulf of Trieste (Northern Adriatic Sea) flocculent, amorphous aggregates known as marine snow reach maximum density and dimensions up to 20cm in diameter during summer months. Sampling of these fragile macro-aggregates was carried out by SCUBA-divers.
A large detrital component was found to be embedded in an organic matrix together with a large array of intact phytoplankton species. Heterotrophic bacterial density ranged from 2–65 × 108 cells-g-1 (marine snow dry wt) and is therefore of the same order of magnitude as in the surface layer of the sediments of the Gulf. In terms of biomass, bacteria reached only 30–95% of heterotrophic microflagellates.
A mean abundance of marine snow of 5g (marine snow dry wt) m-3 was obtained for the water-column above the pyenolinc. At this boundary layer, however, a mean abundance of about 10g (marine snow dry wt) m-3 led to the formation of a distinct, 10-50cm thick layer. Based on these data and sedimentation rates of marine snow to the pyenoclinc (38 g [marine snow dry wt] m-2 d-1 ) the potential ecological significance of these macro-aggregates for the pelagic system of the Gulf of Trieste is discussed. 相似文献
A large detrital component was found to be embedded in an organic matrix together with a large array of intact phytoplankton species. Heterotrophic bacterial density ranged from 2–65 × 10
A mean abundance of marine snow of 5g (marine snow dry wt) m