Photosynthetic Efficiency in Lawson's Bay on the East Coast of India

Seasonal variations in the efficiency of utilization of radiant energy by phytoplankton photosynthesis in a tropical embayment followed the same pattern as that of primary production. showing that incident radiation did not limit phytoplankton production. Peak values in primary production and photosynthetic efficiency coincided with periods of nutrient enrichment caused either by upwelling during the southwest monsoon or by run-off during the northeast, monsoon. A world-wide comparison of published data on photosynthetic efficiencies in different latitudes showed that higher efficiency is achieved in the tropics, where the values are similar to those observed on phytoplankton cultures. Based on the maximum efficiency of photosynthesis attained, three regimes can be recognized in tropical waters: 1) regions of upwelling with a maximum of 6%,. 2) coastal bays with 0.7%, 3) oceanic regions with 0.24%.     

An Examination of Cell Volume in Dominant Phytoplankton Species of the Central and Southern Adriatic Sea

The phytoplankton biomass expressed as total cell volume is often of doubtful value due to cell size and volume variations in the organisms present. Cell volume calculations for 95 phytoplankton species and volume-frequency diagrams for 25 dominant species were analyzed for the Adriatic Sea. Recommendations for more precise work dealing with phytoplankton cell volume and biomass are given. Temporal variations in the average microplankton cell volume are presented and discussed.     

Phytoplankton population density and volume as indicators of eutrophication in the eastern part of the Adriatic Sea

Population density and volume-biomass of microplankton, nanoplankton and total phytoplankton were analyzed at 14 stations along the eastern part of the Adriatic Sea. Based upon data frequency distribution, four categories of ecosystems were established in the investigated area. Criteria for ecosystem categorization and biological evaluation of eutrophication are proposed.     

Yearly variation in primary productivity of marine phytoplankton from Cabo Frio (RJ,Brazil) region

Light saturation curves of natural assemblages of phytoplankton at 4 stations in Cabo Frio coastal waters were examined and related to changes in environmental conditions, based on 263 experiments carried out weekly during two years. No differences in specific productivity at saturating light (Pm ^B ) between stations were detected. Global mean value of Pm ^B was 4.7 mgC mgChla ^–1 h^–1 with a range from 0.50 to 15.29. Significant seasonal variations were not observed. Correlation and regression analysis attributed most of Pm ^B variation to temperature, salinity, nutrients and the phaeopigment: chlorophyll-a ratio.     

Some characteristics of the community of autotrophs of Lake Sevan in connection with its eutrophication

Eutrophication of Lake Sevan caused by the artificial lowering of water level was accompanied by changes in the structure and dynamics of the planktonic communities. A dominance of diatoms up to 1983 was changed to that of green algae in the last years. Primary production of plankton rose and then decreased in the process of eutrophication. The annual average primary production in 1982–1986 — 250 g C m^–2 yr^–1 — is evidently close to the steady state production under the present morphometry of the lake. The activity coefficient of phytoplanktonic photosynthesis changed within relatively narrow limits, in spite of significant changes in the concentrations of major nutrients and in the structure and productivity of the phytoplankton.     

Enclosure Experiments with Low-dose Additions of Phosphorus and Nitrogen in the Acidified Lake Njupfatet,Central Sweden

Experiments involving low-dose additions of phosphate, ammonium, nitrate and ADP, one by one and in combination, were performed in small (350 litre) in-situ enclosures in a moderately acid (pH 5.4) lake. Before manipulation, all large filter-feeding animals were removed by filtration. Phytoplankton responded to the nutrient additions only when both phosphorus and nitrogen were added, thus indicating a close balance between phosphorus and nitrogen limitation in the system. Variation of the inorganic nitrogen-source resulted in species-specific responses by phytoplankton. With ammonium as the nitrogen source Merismopedia tenuissima was favoured, regardless of whether this species was dominant in the phytoplankton community at the beginning of the experiment or not. With nitrate as nitrogen source Peridinium inconspicuum, which was never particularly common at the beginning of the experiments, was favoured. No other species of phytoplankton present in the bags was able to outcompete these two species as long as inorganic nutrients were added. With ADP as phosphorus source together with nitrate, a third species, Dictyosphaerium cf. botrytella, was favoured and reached dominance. The zooplankton community remaining in the bags, dominated by rotifers and calanoid nauplii, did not respond to the fertilization-induced increases in the total biomass of phytoplankton.     

三亚湾秋、冬季浮游植物和细菌的生物量分布特征及其与环境因子的关系

分别于2004年10月(秋季)和2005年1月(冬季)对三亚湾进行了现场综合调查,研究了海区浮游植物和细菌生物量的分布特征,探讨了它们与DIN、PO34-、DO、BOD5等环境因子的关系。结果表明,海区平均叶绿素a浓度秋、冬季分别为:(1·40±0·78)mg/m3和(2·25±3·62)mg/m3;浮游植物生物量秋季为:(70·36±38·91)mgC/m3,冬季为:(112·57±181·38)mgC/m3。海区细菌的丰度秋、冬季分别为:(9·87±5·90)×108cells/L和(6·58±2·43)×108cells/L;平均细菌生物量秋季为:(19·73±11·81)mgC/m3,冬季为:(13·15±4·86)mgC/m3。表、底层浮游植物和细菌的生物量分布均呈现三亚河口最高,离岸逐渐降低的态势,三亚河的陆源物质输送及其入海扩散是引起此分布特征的主要原因。温度是造成秋季细菌的生物量高于冬季的原因之一。溶解无机氮为控制表层浮游植物和细菌分布的重要因子。秋季除表层DIN外各环境因子与浮游植物和细菌生物量都不存在明显的相关性;冬季表层DIN、PO43-、DO和BOD5均在p<0·01水平下与二者呈非常显著相关,底层仅DIN和BOD5在p<0·01水平下与二者呈非常显著正相关。三亚湾浮游细菌和浮游植物生物量间的相关性明显,初级生产是水域浮游细菌分布的重要影响因素。     

Dynamic analysis of phytoplankton community characteristics in Daya Bay, China

Daya Bay is a large bay along the southern coast of China. The composition, abundance, community structure and diversity of phytoplankton in Daya Bay were investigated to assess its status in different seasons in 2002, and a total of 48 genera and 114 species of phytoplankton were identified. The cell abundance of phytoplankton varied from 5.79 × 10⁴ cells/m³ to 5.37 × 10⁶ cells/m³ with an average of 1.14×10⁶ cells/m³. The largest community was Bacillariophyta containing 84 taxa, and its average abundance was 1.08 × 10⁶ cells/m³. Annual abundance variations show a typical one-peak cycle, with the highest peak recorded during summer and the lowest recorded during autumn. The ecotypes of phytoplankton were mostly alongshore warm-water species; however, marine warm-water species and eurytopic species during winter and autumn are more abundant than during the other seasons. The dominant species were diverse and varied with seasons. The species diversity index of phytoplankton in Daya Bay was low during summer, especially near the nuclear power station (NPS) and the aquaculture farms during summer and autumn. Community structure and cell abundance were categorized in relation to monsoon, current and anthropological activities. It is presented that the temperature and hydrodynamics in conjunction with the pattern of nutrients (DIN, DIP and N/P) availability and depletion affect the composition, abundance, community structure, community succession and diversity of phytoplankton.     

Dynamic analysis of phytoplankton community characteristics in Daya Bay, China

Daya Bay is a large bay along the southern coast of China. The composition, abundance, community structure and diversity of phytoplankton in Daya Bay were investigated to assess its status in different seasons in 2002, and a total of 48 genera and 114 species of phytoplankton were identified. The cell abundance of phytoplankton varied from 5.79 × 10⁴ cells/m³ to 5.37 × 10⁶ cells/m³ with an average of 1.14×10⁶ cells/m³. The largest community was Bacillariophyta containing 84 taxa, and its average abundance was 1.08 × 10⁶ cells/m³. Annual abundance variations show a typical one-peak cycle, with the highest peak recorded during summer and the lowest recorded during autumn. The ecotypes of phytoplankton were mostly alongshore warm-water species; however, marine warm-water species and eurytopic species during winter and autumn are more abundant than during the other seasons. The dominant species were diverse and varied with seasons. The species diversity index of phytoplankton in Daya Bay was low during summer, especially near the nuclear power station (NPS) and the aquaculture farms during summer and autumn. Community structure and cell abundance were categorized in relation to monsoon, current and anthropological activities. It is presented that the temperature and hydrodynamics in conjunction with the pattern of nutrients (DIN, DIP and N/P) availability and depletion affect the composition, abundance, community structure, community succession and diversity of phytoplankton.     

Biogenic silica and phosphorus accumulation in sediments as indices of eutrophication in the Laurentian Great Lakes

Biogenic silica (BSi), total phosphorus (TP), and biologically available phosphorus (AVP) were measured in short cores from Lake Michigan, Lake Erie, and Lake Ontario. Peaks in BSi concentration and peaks in BSi:TP or BSi:AVP ratios provided stratigraphic signals of water column silica (Si) depletion as a response of increased diatom production to P enrichment and decreased diatom production resulting from silica depletion. By contrast the stratigraphic record of P accumulation provided very weak signals of the historical nutrient enrichment in the water column. These results indicate that system P recycling has a higher rate constant than Si recycling and, as a consequence, that relatively small levels of P enrichment can increase diatom production and sedimentation eventually causing Si depletion and Si-limited diatom production in the water mass.     

广东省典型水库浮游植物群落特征与富营养化研究

研究了广东省19座主要水库2000年丰水期和枯水期浮游植物状况,并根据浮游植物群落结构和多样性指数对水库进行营养状况评价。结果表明,东江流域的新丰江和白盘珠水库水质良好,属于贫营养型水库;大部分水库为中营养型,而鹤地、契爷石和石岩这3座位于沿海经济发达地区水库属于富营养型。流域上游水库水质明显优于下游水库,山区水库水质优于沿海水库,东江流域水库水质普遍较好。北江流域次之,而粤西沿海和珠江三角洲地区各水库均受到不同程度的污染。     

Phytoplankton and zooplankton as indicators of water quality in Discovery Bay,Jamaica

Several investigations exist which use planktonic communities as indicators of water quality in Jamaican and Caribbean Bays, however, few are conducted before there are obvious effects of eutrophication. Therefore, most of our ‘baseline’ data are for bays already severely affected by pollution. This study was conducted to assess water quality in Discovery Bay, Jamaica, before there were severe signs of eutrophication. The bay was monitored over a 12-month period (October 1995–September 1996) using 10 stations. Physicochemical data indicated a well mixed upper 5 m of water column, below which discontinuities in temperature/salinity profiles indicated the influence of colder, more saline waters associated with deep offshore currents. Physicochemical variables were within the range for oligotrophic systems with a tendency towards mesotrophic in localized areas close to the shoreline. Signs of anthropogenic stress were associated with the eastern, southwestern and western sections of the bay. Of the over 120 species of phytoplankton found in the waters of Discovery Bay, most were neritic/oceanic and diatoms dominated while 11 were found to be potentially harmful species. While these harmful species occurred at all stations they occurred most frequently at stations on the eastern side of the bay. About 107 zooplankton species were identified, 52 of which were copepods. The species also represented a mix of neritic and oceanic taxa and mean abundances for the area ranged from 1077 m⁻³ at the mouth of the bay to 3794 m⁻³ close to the south shore (station 6). Generally stations closest to shore had greater zooplankton abundances than centrally located bay stations and stations close to oceanic influence. Acartia tonsa and Lucifer faxoni showed greatest densities at shoreline areas of the bay while Oithona plumifera, Undinula vulgaris and Temora stylifera were important at stations closest to oceanic influences. These species were thus considered as indicators of these different areas within the bay. From physicochemical data and the planktonic assemblage, Discovery Bay cannot be considered polluted, it is still more accurately classified as generally pristine with mesotrophic zones in the eastern and southeastern sections of the bay. These data therefore provide a real baseline of conditions for similar tropical coastal embayments.     

Biomass, protein- and carbohydrate-composition of phytoplankton in Varna Bay, Black Sea

It was shown that phytoplankton from the Varna Bay, Black Sea, has significantly more suspended carbohydrates, proteins and biomass in July than in April. The dominant species were Bacillariophyceae and Dinophyceae. Electrophoretic and fluorescent spectra have shown the main differences in molecular weight and stability of phytoplankton proteins. Phytoplankton included specific proteins distributed over a limited range of molecular weights between 14 and 72 kilodaltons (kDa). The most abundant protein constituents in phytoplankton samples collected in April were around 45–55 kDa. The seasonal variations of the environment influence the quantitative and qualitative changes in phytoplankton.     

Inorganic carbon uptake by phytoplankton in Vineyard Sound,Massachusetts. II. Comparative primary productivity and nutritional status of winter and summer assemblages

Using time-course, natural-light incubations, we assessed the rate of carbon uptake at a range of light intensities, the effect of supplemental additions of nitrogen (as NH₄⁺ or urea) on light and dark carbon uptake, and the rates of uptake of NH₄⁺ and urea by phytoplankton from Vineyard Sound, Massachusetts from February through August 1982. During the winter, photoinhibition was severe, becoming manifested shortly after the start of an incubation, whereas during the summer, there was little to no evidence of photoinhibition during the first several hours after the start of an incubation. At light levels which were neither photoinhibiting nor light limiting, rates of carbon uptake normalized per liter were high and approximately equal during winter and summer (22–23 μg C·l^?1 · h^?1), and low during spring (<10 μgC·l^?1· h^?1). In contrast, on a chlorophyll a basis, rates of carbon fixation were as high during spring (15–20μg C·μg Chl a^?1·h^?1), when concentrations of chlorophyll a were at the yearly minimum (<0.5 μg · l^?1) as during the summer, when chlorophyll a concentrations were substantially higher (0.8–1.3 μg · l^?1). Highest rates of NH₄⁺ and urea uptake were observed during summer, and at no time of the year was there evidence for severe nitrogen deficiency, although moderate nitrogen nutritional stress was apparent during the summer months.     

Response of bacteria and phytoplankton to contaminated sediments from Trenton Channel,Detroit River

Several types of bioassays were used in 1986 and 1987 to investigate the effect of contaminated sediments on natural populations of bacteria and phytoplankton from the Trenton Channel, Detroit River. The approach included the measurement of uptake of ³H-glucose or ³H-adenine by bacteria and ¹⁴C-bicarbonate by phytoplankton in the presence of different amounts of Trenton Channel and Lake Michigan (control) sediments. Trenton Channel sediments are contaminated by high levels of toxic organic compounds and metals, especially zinc, lead, and copper. Because levels of biomass of bacteria and phytoplankton varied widely among the different bioassays, it was necessary to adjust uptake rates for biomass. Biomass adjustments were made using acridine orange counts for bacteria and chlorophyll measurements for phytoplankton. The results show a statistically significant suppression of uptake of substrates for both bacteria and phytoplankton with increasing amounts of sediment. Uptake was suppressed as much as 90 percent for bacteria and 93 percent for phytoplankton at 1200 mg l^-1 of Trenton Channel sediments compared to bioassays without sediment. Uncontaminated Lake Michigan sediment suppressed uptake much less than Detroit River sediment; the difference in suppression of uptake between the two types of sediment was statistically significant for both bacteria and phytoplankton.Contribution No. 518 of the Center for Great Lakes and Aquatic Sciences of the University of Michigan.     

The planktonic food web structure of a temperate zone estuary,and its alteration due to eutrophication

Hydrobiologia - Current conventional wisdom argues that human-induced excesses in nutrient loadings to estuaries often stimulate ‘excess’ algal production leading to hypoxia, via...     

Seasonal Distribution of Phytoplankton in Yellowknife Bay,Great Slave Lake

The factors influencing the seasonal distribution of phytoplankton were determined between July 1975 and December 1977 in Yellowknife Bay, Great Slave Lake. The initiation of the spring bloom occurred during April of each year in response to changing light conditions and despite the 0 °C water temperatures. Although the plankton showed some fluctuations in density (100–400 mg/m³) during the summer, there was no vernal decrease in the size of the populations. The end of the growing season was characterized by a sharp drop in numbers near the end of October. Multiple regression analysis indicated that changes in the standing crop of the plankton during the summer were primarily related to temperature (r = 0.60) and the concentrations of NO₃–N (r=–0.74) and SiO₂ (r=–0.82). Changing light conditions probably had little effect on the population during the growing season. Chlamydomonas lapponica was dominant during April of each year. While the growth of this species caused a reduction in the concentrations of total phosphorus and NO₃–N, the level of SiO₂ remained constant and consequently diatoms (Asterionella formosa, Stephanodiscus astraea, Diatoma tenue var. elongatum and Melosira islandica) waxed rapidly during May. By the first of June, nutrient concentrations were low, thereby permitting the development of Dinobryon bavaricum and Dinobryon cylindricum. The extremely rapid decrease in the densities of common species during the fall was probably due to the rapid decline in temperature and light levels and the formation of ice on the bay.     

A fish kill of massive proportion in Kuwait Bay, Arabian Gulf, 2001: the roles of bacterial disease, harmful algae, and eutrophication

In August and September 2001, Kuwait Bay, a semi-enclosed embayment of the Arabian Gulf, experienced a massive fish kill involving over >2500 metric tons of wild mullet (Liza klunzingeri), due to the bacterium Streptococcus agalactiae. In the Bay, this event was preceded by a small fish kill (100–1000 dead fish per day) of gilthead sea bream (Sparus auratus) in aquaculture net pens associated with a bloom of the dinoflagellate Ceratium furca. Sea bream were found to be culture positive for S. agalactiae, but did not show any visible signs of disease. Unusually warm temperatures (up to 35 °C) and calm conditions prevailed during this period. As the wild fish kill progressed, various harmful algae were observed, including Gymnodinium catenatum, Gyrodinium impudicum, and Pyrodinium bahamense var. compressum. Cell numbers of G. catenatum and G. impudicum exceeded 10⁶ l⁻¹ in some locations. All fish tested below the limits of detection for paralytic shellfish poisoning (PSP) and brevetoxins. Clams (Circe callipyga) were positive for PSP but at levels below regulatory limits. Nutrient concentrations, both inorganic and organic, were highly variable with time and from site to site, reflecting inputs from sewage outfalls, the aquaculture operations, a high biomass of decomposing fish, and other sources. It is hypothesized that many factors contributed to the initial outbreak of the bacterial disease, including unusual warm and calm conditions. The same factors, as well as enriched nutrient conditions, also apparently were conducive to the subsequent HAB outbreaks. The detection of PSP, while below regulatory limits, warrants further monitoring to protect human health.     

白洋淀附着藻类的初级生产力及其与水质的关系

附着藻类是湖泊中主要的生产者,尤其是草型湖泊。但与浮游藻类相比,针对附着藻类初级生产的研究还相对较少。采用原位调查与实验模拟相结合的方法测定2014—2015年间白洋淀附植藻类和附泥藻类的现存量和初级生产力,并对附着藻类初级生产与白洋淀水体理化参数的关系进行分析。结果表明,不同采样季节的附植藻类和附泥藻类的叶绿素a分别为34.83—245.22μg/cm~2和26.08—297.40μg/cm~2,无灰干重分别为0.46—5.21g/m~2和0.61—5.81g/m~2。两种附着藻类的生物量都在8月最高,4月和11月最低。空间分布上,南刘庄、府河入口的附着藻类生物量显著高于采蒲台和枣林庄。白洋淀附植藻类和附泥藻类的年均总初级生产分别为494.20mg C m~(-2)d~(-1)和474.45mg C m~(-2)d~(-1),呼吸速率为522.63mg C m~(-2)d~(-1)和508.98mg C m~(-2)d~(-1),净初级生产为-28.44mg C m~(-2)d~(-1)和-34.52mg C m~(-2)d~(-1)。白洋淀附着藻类初级生产力具有明显的时空分布规律,8月最高,6月次之,4月和11月最低,空间分布呈自西向东递减的趋势,在府河入淀口和南刘庄处最高,枣林庄和采蒲台最低。水质较好的区域的净初级生产力为正值,表明这些区域附着藻类以自养型群落为主,水质较差区域的净初级生产力为负值,则该区域以异养型群落为主。运用冗余分析法(RDA)探讨附着藻类与水质因子之间的关系,并采用向前引入法对水质因子进行逐步筛选,Monte Carlo置换检验结果显示,总磷、浮游植物叶绿素a、高锰酸盐指数、氨氮、水温、透明度、溶解氧和氮磷比是影响附着藻类生物量和初级生产的关键水质因子。附着藻类的总初级生产与水体富营养化程度呈正相关关系。     

Carbon isotope ratio and photosynthetic activity of phytoplankton in the eutrophic Mikawa Bay,Japan

Primary production by phytoplankton in the eutrophic Mikawa Bay, Japan, was studied by simultaneous measurements of natural carbon isotope ratio (δ ¹³C) and short-term carbon uptake rates (¹³C tracer study) of size-fractionated nannoplankton (<10 μm) and net plankton (>10 μm) samples. Short-term photosynthetic rates, which represent the physiological state of algae, were variable regardless of standing stock sizes. Theδ ¹³C values of particulate organic carbon (POC) in June and July displayed horizontal variations for both the net plankton fraction (−19.8 to −12.7‰) and the nannoplankton fraction (−22.0 to −12.8‰). For both fractions, low concentrations of POC had more negativeδ ¹³C values (−22 to −18‰). Highδ ¹³C values for the net plankton were found when POC concentrations were much higher, due to red tide. This suggests that the increase in algal standing crop for the net plankton fraction resulted from accelerated photosynthetic activity. However the nannoplankton fractions with higher POC values have relatively lowδ ¹³C values.