Vertical distribution of suspended particulate matter in the Caspian Sea in early summer

The features of the vertical distribution of chlorophyll a, particulate organic carbon and its isotopic composition, total suspended particulate matter (SPM), and the structure of the phytoplankton community in the Middle and South Caspian Sea in May–June 2012 are discussed. The subsurface chlorophyll a maximum (SCM) was found everywhere at depths of ~20 to 40–60 m. The position of this layer is confined to the depth of the seasonal thermocline, which is determined by the development of a cold-water (dark) phytocenosis. The genesis of this layer was studied. The increase in chlorophyll a concentration in this layer is caused by an abundance of phytoplankton or an increased concentration of this phytopigments per algal cell. The highest values of the studied organic compounds and phytoplankton biomass are revealed as close to the seasonal thermocline extending from the southern periphery of the Derbent Depression to the Apsheron Sill, which is determined by the bottom topography. The presence of chlorophyll a at depths exceeding 300 m (up to ≥1 mg/m³) was revealed. This was supported by findings of individual algal cells containing chlorophyll a and even their accumulations in the deep water layer. The most probable mechanisms responsible for the presence of these cells at the deep water level are discussed in the paper. The vertical distribution of the values of the organic carbon isotopic composition is primarily controlled by the vertical structure of phytoplankton and chlorophyll a in the water column up to ~500 m and by biogeochemical processes at the redox barrier (~600 m layer). The relative stability of chlorophyll a and the stability of pheophytin a in anaerobic environments were verified. A significant amount of weakly transformed chlorophyll a was found close the sea bottom.     

引入拖曳系数参数化的海冰自由漂流模拟研究

Many interesting characteristics of sea ice drift depend on the atmospheric drag coefficient(C_a) and oceanic drag coefficient(C_w).Parameterizations of drag coefficients rather than constant values provide us a way to look insight into the dependence of these characteristics on sea ice conditions.In the present study,the parameterized ice drag coefficients are included into a free-drift sea ice dynamic model,and the wind factor α and the deflection angle θ between sea ice drift and wind velocity as well as the ratio of C_a to C_w are studied to investigate their dependence on the impact factors such as local drag coefficients,floe and ridge geometry.The results reveal that in an idealized steady ocean,C_a/C_w increases obviously with the increasing ice concentration for small ice floes in the marginal ice zone,while it remains at a steady level(0.2-0.25) for large floes in the central ice zone.The wind factor α increases rapidly at first and approaches a steady level of 0.018 when A is greater than 20%.And the deflection angle θ drops rapidly from an initial value of approximate 80° and decreases slowly as A is greater than20%without a steady level like α.The values of these parameters agree well with the previously reported observations in Arctic.The ridging intensity is an important parameter to determine the dominant contribution of the ratio of skin friction drag coefficient(C_s' /C_s) and the ratio of ridge form drag coefficient(C_r'/C_r) to the value of C_a/C_w,α,and θ,because of the dominance of ridge form drag for large ridging intensity and skin friction for small ridging intensity among the total drag forces.Parameterization of sea ice drag coefficients has the potential to be embedded into ice dynamic models to better account for the variability of sea ice in the transient Arctic Ocean.     

Phytoplankton characteristics and hydrological conditions in the western part of the Sea of Okhotsk in the spring of 1999 and 2000 based on expeditionary and satellite data

Using the data obtained in 1999–2000 during the spring bloom of phytoplankton (late May–early June), the variability of the pigment concentrations, the phytoplankton biomass and species compositions, and the hydrological conditions on the eastern shelf of Sakhalin Island was studied. The study resulted in revealing 135 microalgae species belonging to eight divisions. The most diversely presented were the Dinophyta dinoflagellates and Bacillariophyta diatoms (70 and 53 species, respectively). The concentration of chlorophyll a in the euphotic zone amounted, on average, to 3.8 mg/m³ in 1999 and 2.4 mg/m³ in 2000. It was shown that, in the northern and southern parts of the coastal zone, the concentration of chlorophyll a and the phytoplankton density in the spring were considerably different and depended on the hydrological conditions. In the north, their maximum values were found in the area of the depth break and were determined by the tidal mixing. The increased algae concentrations and temperature inversions at depths of 400–600 m confirm the downslope sliding of the near-bottom shelf waters. In the southern part, the high phytoplankton concentrations in the surface layer in 1999 confirmed by the monthly averaged estimates from the SeaWiFS satellite color scanner were caused by the abnormal northward propagation of the Soya Current waters and by intense tidal mixing.     

<Emphasis Type="Italic">In-situ</Emphasis> measured primary productivity of ice algae in Arctic sea ice floes using a new incubation method

Recent changes in climate and environmental conditions have had great negative effects such as decreasing sea ice thickness and the extent of Arctic sea ice floes that support ice-related organisms. However, limited field observations hinder the understanding of the impacts of the current changes in the previously ice-covered regions on sea ice algae and other ice-related ecosystems. Our main objective in this study was to measure recent primary production of ice algae and their relative contribution to total primary production (ice plus pelagic primary production). In-situ primary productivity experiments with a new incubation system for ice algae were conducted in 3 sea ice cores at 2 different ice camps in the northern Chukchi Sea, 2014, using a ¹³C and ¹⁵N isotope tracer technique. A new incubation system was tested for conducting primary productivity experiments on ice algae that has several advantages over previous incubation methods, enabling stable carbon and nitrogen uptake experiments on ice algae under more natural environmental conditions. The vertical C-shaped distributions of the ice algal chl-a, with elevated concentrations at the top and bottom of the sea ice were observed in all cores, which is unusual for Arctic sea ice. The mean chl-a concentration (0.05 ± 0.03 mg chl-a m^?3) and the daily carbon uptake rates (ranging from 0.55 to 2.23 mg C m^?2 d^?1) for the ice algae were much lower in this study than in previous studies in the Arctic Ocean. This is likely because of the late sampling periods and thus the substantial melting occurring. Ice algae contributed 1.5–5.7% of the total particulate organic carbon (POC) contents of the combined euphotic water columns and sea ice floes. In comparison, ice algae contributed 4.8–8.6% to the total primary production which is greater than previously reported in the Arctic Ocean. If all of the ice-associated productions were included, the contributions of the sea ice floes to the total primary production would be greater in the Arctic Ocean and their importance would be greater in the arctic marine ecosystems.     

大型水母沙海蜇暴发的温带贫营养海洋生态系统中细菌和浮游植物的关系

Bacterial abundance, phytoplankton community structure and environmental parameters were investigated to study the relationships between bacteria and phytoplankton during giant jellyfish Nemopilema nomurai blooms in the central Yellow Sea during 2013. N. nomurai appeared in June, increased in August, reached a peak and began to degrade in September 2013. Results showed that phosphate was possible a key nutrient for both phytoplankton and bacteria in June, but it changed to nitrate in August and September. Phytoplankton composition significantly changed that pico-phytoplankton relative biomass significantly increased, whereas other size phytoplankton significantly decreased during jellyfish bloom. In June, a significantly positive correlation was observed between chlorophyll a concentration and bacterial abundance(r=0.67, P0.001, n=34).During jellyfish outbreak in August, there was no significant correlation between phytoplankton and bacteria(r=0.11, P0.05, n=25), but the relationship(r=0.71, P0.001, n=31) was rebuilt with jellyfish degradation in September. In August, small size phytoplankton occupied the mixed layer in offshore stations, while bacteria almost distributed evenly in vertical. Chlorophyll a concentration significantly increased from(0.42±0.056) μg/L in June to(0.74±0.174) μg/L in August, while bacterial abundance just slightly increased. Additionally, the negative net community production indicated that community respiration was not entirely determined by the local primary productivity in August. These results indicated that jellyfish blooms potentially affect coupling of phytoplankton and bacteria in marine ecosystems.     

Phytoplankton production characteristics in the Eastern Atlantic and Atlantic sector of the Southern Ocean in October–November 2004

Production parameters of surface phytoplankton were measured along three transects: La Manche-Cape Town (I); Cape Town-54°S (II); 0°-49°W (along 54°S) (III). The Canary upwelling waters were most productive along transect I, where the surface chlorophyll a (Chl ₀) and the surface primary production (PP ₀) were as high as 4.3 mg/m³ and 173 mg C/m³ per day, respectively. Mosaic patterns in the distribution of these parameters were recorded in the northeastern regions of the South Subtropical Anticyclonic Gyre (Chl ₀ = 0.03–0.35 mg/m³; PP ₀ = 1.6–12.6 mg C/m³ per day). Along transect II, the average twofold southward increase in Chl ₀ (from 0.2 to 0.4 mg/m³) and the concurrent decline of the phytoplankton assimilation activity ( AN ₀) resulted in deviations from typical latitudinal changes inPP ₀. At most sites, PP ₀ values varied between 6 and 15 mg C/m³ per day. Negligible changes in Chl ₀ (0.36–0.85 mg/m³), PP ₀ (8–19 mg C/m³ per day), and AN ₀ (0.7–1.6 mg C/mg chl a per hour) were registered for the oceanic waters along transect III. Along all the transects, PP ₀ depended on Chl ₀ to a greater extent than AN ₀. The values of the latter parameter were largely determined by the water temperature and showed a slight correlation with the insolation. Along transect II, the integrated primary production (PP _int) and the layer-integrated chlorophyll a in the upper 200 m (Chl _0–200) generally varied from 180 to 360 mg C/m² per day and from 30 to 70 mg/m², respectively. In the Polar Front region, an increase in Chl _0–200, PP _int, Chl ₀, and PP ₀ up to respective values of 190 mg/m², 520 mg C/m² per day, 1.2 mg/m³, and 32 mg C/m³ per day was observed. A comparison of the water column (0–100 m) stability with the vertical distribution of the primary production and chlorophyll content along transect II implies that the thick (>100 m) upper mixed layer (UML) formed in response to the strong water cooling and wind forcing was largely responsible for the limited primary production in the Subantarctic and Antarctic regions. The large UML thickness resulted in an intense removal of plant cells from the photosynthetic layer and light starvation of a significant (up to 60%) part of the phytoplankton community.     

Feeding selectivity of calanoid copepods on phytoplankton in Jangmok Bay,south coast of Korea

Grazing impacts of calanoid copepods on size-fractionated phytoplankton biomass [chlorophyll (Chl)-a] were measured in Jangmok Bay, Geoje Island, Korea, monthly from November 2004 to October 2005. The ingestion rate of calanoid copepods on total phytoplankton biomass ranged between 1 and 215 ng Chl-a copepod^?1 day^?1 during bottle incubations. Results indicated that microphytoplankton (> 20 μm) was the primary food source for calanoid copepods in grazing experiments on 3 phytoplankton size categories (< 3 μm, 3–20 μm, and > 20 μm). The ingestion rate on microphytoplankton showed a significant increase (r = 0.93, p < 0.01) with Chl-a concentration. Nanophytoplankton (3–20 μm) showed a negative ingestion rate from June 2005 to October 2005, but the reason is not completely understood. Calanoid copepods were unable to feed efficiently on picophytoplankton (< 3 μm) due to unfavorable size. Calanoid copepods removed between 0.1% and 27.7% (average, 3.6 ± 15.8%) of the phytoplankton biomass daily during grazing experiments. Grazing pressure was high in winter and early spring (January–March: 15.6–27.7%), while low in summer (June–August: ?33.1–0.0%) and autumn (September–November: ?1.4–5.1%). Results suggest that calanoid copepods play an important role in controlling the biomass and size structure of phytoplankton in winter and early spring.     

Spatial Distribution and Seasonal Dynamics of the Chlorophyll <Emphasis Type="Italic">a</Emphasis> Concentration in the Sea of Azov Based on MERIS Images

The chlorophyll a concentration (Cchl a) in the Sea of Azov is estimated by the two-band NIR-red algorithm [34] from MERIS images for 2002–2012. The sea-truth spectrophotometric measurements and MERIS remote estimates of Cchl a are compared. The monthly average Cchl a values are mapped from MERIS data for its lifetime for the first time. The features of the spatiotemporal distribution of Cchl a are ascertained. Differences between the seasonal dynamics of Cchl a in the Sea of Azov according to the literature data and the dynamics derived from MERIS data are found, namely: the summer–autumn phytoplankton growth period is longer than the spring period and is characterized by higher Cchl a values throughout the water area.     

Primary production and chlorophyll distributions in the subtropical and tropical waters of the Atlantic Ocean in the autumn of 2002

In October and November 2002, high and relatively high values of the chlorophyll a concentration at the sea surface (C _chl) were observed in the English Channel (0.47 mg/m³), in the waters of the North Atlantic Current (0.25 mg/m³), in the tropical and subtropical anticyclonic gyres (0.07–0.42 mg/m³), and also in the southwestern region of the southern subtropical anticyclonic gyre (usually 0.11–0.23 mg/m³). The central regions of the southern subtropical anticyclonic gyre (SATG) and the North Atlantic tropical gyre (NATR) were characterized by lower values of C _chl (0.02–0.08 mg/m³ for the SATG and 0.07–0.14 mg/m³ for the NATR). At most of the SATG stations, the values of the surface primary production (C _phs) varied from 2.5 to 5.5 mg C/m³ per day and were mainly defined by the fluctuations of C _chl (r = +0.78) rather than by those of the assimilation number (r = +0.54). The low assimilation activity of phytoplankton in these waters (1.3–4.6 mg chl a per hour) pointed to a lack of nutrients. An analysis of the variability of their concentration and the composition of photosynthetic pigments showed that, in the waters north of 30° N, the growth of phytoplankton was mostly restricted by the deficiency of nitrogen, while, in more southern areas, at the majority of stations (about 60%), the phosphorus concentrations were the minimum. At the low concentrations of nitrates and nitrites, ammonium represented itself as a buffer that prevented planktonic algae from extreme degrees of nitric starvation. In the tropical waters and in the waters of the SATG, the primary production throughout the water column varied from 240 to 380 mg C/m² 30° per day. This level of productivity at stations with low values of C _chl (<0.08 mg/m³) was provided by a well-developed deep chlorophyll maximum and a high transparency of the water. The light curves of photosynthesis based on in situ measurements point to the high efficiency of utilizing the penetrating solar radiation by phytoplankton on cloudy days.     

On the spatial–temporal variations in the chlorophyll-<Emphasis Type="Italic">a</Emphasis> concentration on the Peter the Great Bay shelf during the winter–spring phytoplankton bloom according to satellite and subsatellite data

Chlorophyll-a concentration (C _chl) variations in the cross section within and outside the Peter the Great Bay shelf during different stages of the winter–spring phytoplankton bloom in 2003–2005 has been considered based on a ship (obtained during the R/V Akademik M.A. Lavrent’ev voyage of February 26 to March 9, 2003) and MODIS-Aqua spectroradiometer and the SeaWiFS color-scanner satellite data. A comparison of the C _chl variability obtained from the ship and satellite data indicates that these data are inconsistent. According to satellite data obtained at the MUMM atmospheric correction, the C _chl variability is distorted less than the NIR-correction data. Studying the variations in the coefficients of light absorption by the detritus and yellow substance (a _dg) and light backscattering by suspended particles (b _bp), C _chl, chlorophyll-a fluorescence (F _chl) according to the satellite data allow us to state that the variations in the discrepancy between the satellite and ship C _chl values are mainly caused by the variations in the content of the detritus and yellow substance in water. Based on the satellite data, it has been revealed that the a _dg values increase with increasing wind mixing after the phytoplankton bloom (about 2–5 km areas where the a _dg, C _chl, F _chl, and bbp values abruptly increased in 2005, apparently due to eddy formation). It has been indicated that the F _chl characteristic, which is close to C _chl, increases when the favorable conditions for the phytoplankton bloom deteriorate. Therefore, this characteristic cannot be used to identify C _chl under the indicated conditions.     

Variability of Particulate Organic Phosphorus in the Northwestern Part of the Black Sea

Based on long-term (1985–1995) monitoring data, the paper considers the peculiarities of seasonal variability in the spatial and vertical distribution of particulate organic phosphorus (Р_POM) in the surface layer and in the photosynthetic zone in the northwestern Black Sea. Regression equations, experimental data, and satellite observations for the chlorophyll a concentration allowed us to evaluate the seasonal longterm (1979–1995) variability in Р_POM in the surface layer and photosynthesis zone. The ratios of the concentrations of particulate organic carbon, nitrogen, phosphorus, and chlorophyll a are calculated and statistical estimates of seasonal changes in the Р_POM in the areas with different degrees of influence of river runoff and water of open seas are obtained. The consistency of intra-annual changes in the concentrations of Р_POM, chlorophyll a, and phytoplankton biomass is shown, which indicates the role of phytoplankton in the formation of Р_POM and in its intra- and interannual variability in the northwestern part of the sea. It is shown that long-term seasonal variations in Р_POM and related changes in the concentration of chlorophyll a depend on the variability of bulk river runoff, the extent of its abundance in the northwestern shelf, and regional hydrometeorological conditions.     

Spatial distribution of the phytoplankton in the White Sea during atypical domination of dinoflagellates (July 2009)

The species composition and biomass of phytoplankton, concentrations of chlorophyll a (Chl a) and nutrients, and accompanying hydrophysical conditions have been studied in the White Sea on July 6–11, 2009. The temperature of the surface water layer was lower than the multiyear average in July. Dinoflagellates dominated in the entire studied area; this was not the typical event for July. We suggest that domination of dinoflagellates was caused by low water temperature, when the nutrient regeneration rate was insufficient to support diatom growth. The abundance of microalgae and the structure of the phytoplankton community depended on the water structure. Variations in the phytoplankton community structure were caused not by substitution of specific species but rather by variability of the abundance of a single species, Heterocapsa triquetra. The highest phytoplankton biomass has been recorded in weakly stratified waters, where tidal mixing supplied the income of inorganic nutrients. The income of nutrients to the photic layer was limited in the stratified waters of Dvina Bay during the summer low-water period, so the phytoplankton abundance was low. We suggest that the lens of surface desalinated water presumably originated from the outlet of the Dvina River was registered in the central part of the White Sea.     

Grazing Impact of the Copepod <Emphasis Type="Italic">Calanus sinicus</Emphasis> on Phytoplankton in the Northern East China Sea in Late Spring

We investigated the feeding habits of Calanus sinicus during its four developmental stages as copepodite 4 (CIV), copepodite 5 (CV), adult males and females in early June 2015 at 12 sampling stations along the southern coast of Korea to the northern East China Sea, to better understand the role of C. sinicus in controlling phytoplankton stocks. Ingestion rate, daily ration as body carbon, population ingestion rate, and grazing impact were estimated using the gut pigment method. The mean biomass of CVs was the greatest (13.5 mg C m^–3) and that of adult males was the lowest (0.7 mg C m^–3). The ingestion rate per C. sinicus individual tended to increase with developmental stage, with the highest rate in adult females (519 ng chl ind^–1 d^–1) and the lowest rate in CIVs (305 ng chl ind^–1 d^–1). A significant correlation was found between ingestion rate and temperature, but not salinity or chlorophyll-a concentration. The daily ration of C. sinicus as body carbon significantly decreased with increased body weight, with the highest value found in CIVs (66.4%) and the lowest value in adult males (30%). Despite the high ingestion rate of the adults, the mean grazing impact of C. sinicus on phytoplankton biomass, in terms of chlorophyll-a concentration, was the highest in CVs (2.6%), followed by CIVs and adult females, and was the lowest in adult males (0.1%). The higher grazing impact of copepodites than adults underscores the importance of evaluating copepodite stages in the feeding studies of marine food webs.     

桑沟湾养殖生态系统浮游植物的粒径结构及浮游生物对栉孔扇贝碳需求的贡献

The biomass and size fraction of phytoplankton in terms of chlorophyll a(Chl a) was measured during four cruises conducted in April, July, October 2013 and January 2014 in mariculture area, the Sanggou Bay, China.Results show that total Chl a levels in the surface seawater of the Sanggou Bay generally range from 0.10 to 20.46μg/L, with an average value of 2.13 μg/L. Nano-phytoplankton was the most important size-fraction and accounted for about 65.1% of total Chl a. In order to evaluate the importance of the "protozoan trophic link" for energy transfer from the microbial loop to filter-feeding feeders, Zhikong scallop Chlamys farreri was then offered a natural planktonic community as potential prey. Results show that scallops obtained carbon source from natural plankton with the rate of 11 033.05 μg/(g·d). Protists(nanoflagellates and ciliates) were the dominant source of carbon retained by scallop(48.78%). The microbial loop provided 58.45% of the carbon source for farmed scallops. These results indicate that the microbial loop represent a valuable trophic resource in mariculture system of the Sanggou Bay.     

2010年西北冰洋浮游植物区域差异与环境关系

Global warming has caused Arctic sea ice to rapidly retreat,which is affecting phytoplankton,the primary producers at the base of the food chain,as well as the entire ecosystem.However,few studies with large spatial scales related to the Arctic Basin at high latitude have been conducted.This study aimed to investigate the relationship between changes in phytoplankton community structure and ice conditions.Fifty surface and 41 vertically stratified water samples from the western Arctic Ocean(67.0°–88°26′N,152°–178°54′W) were collected by the Chinese icebreaker R/V Xuelong from July 20 to August 30,2010 during China's fourth Arctic expedition.Using these samples,the species composition,spatial distribution,and regional disparities of phytoplankton during different stages of ice melt were assessed.A total of 157 phytoplankton taxa(5 μm) belonging to 69 genera were identified in the study area.The most abundant species were Navicula pelagica and Thalassiosira nordenskioeldii,accounting for 31.23% and 14.12% of the total phytoplankton abundance,respectively.The average abundance during the departure trip and the return trip were 797.07×10~2 cells/L and 84.94×10~2 cells/L,respectively.The highest abundance was observed at Sta.R09 in the north of Herald Shoal,where Navicula pelagica was the dominant species accounting for 59.42% of the abundance.The vertical distribution of phytoplankton abundance displayed regional differences,and the maximum abundances were confined to the lower layers of the euphotic zone near the layers of the halocline,thermocline,and nutricline.The species abundance of phytoplankton decreased from the low-latitude shelf to the high-latitude basin on both the departure and return trips.The phytoplankton community structure in the shallow continental shelf changed markedly during different stages of ice melt,and there was shift in dominant species from centric to pennate diatoms.Results of canonical correspondence analysis(CCA) showed that there were two distinct communities of phytoplankton in the western Arctic Ocean,and water temperature,ice coverage and silicate concentration were the most important environmental factors affecting phytoplankton distribution in the surveyed sea.These findings will help predict the responses of phytoplankton to the rapid melting of Arctic sea ice.     

Species composition and seasonal dynamics of the population density and biomass of the genus <Emphasis Type="Italic">Pyramimonas</Emphasis> (Prasinophyceae) from the Russian waters of East/Japan Sea

The species composition and seasonal dynamics of the population density and biomass of the prasinophycean algae of the genus Pyramimonas were investigated in the Russian waters of the East/Japan Sea. According to literature data and the results of our observations, eight species of the prasinophycean algae were identified, and some of them were new for the Russian waters of the East/Japan Sea as follows: P. aff. amylifera Ñonrad, P. aff. cordata McFadden, Hill et Wetherbee, and P. nansenii Braarud. An analysis of their seasonal dynamics showed that the most conspicuous winter peak of the population density of Pyramimonas species in the Amurskii Bay was clearly distinguishable in February. In winter and early spring, the prasinophycean algae made a considerable contribution of 28 to 60% into the total population density on the background of a relatively low biomass, 1.1–14.4% of the total phytoplankton biomass in the Amurskii Bay. In the Golden Horn Bay, the summer peak of the population density of Pyramimonas species was most intensive in June. In summer, during the period of mass development of the algae of the genus Pyramimonas in the Golden Horn Bay, the prasinophycean algae contributed up to 71% of the total population density and up to 84% of the total microalgal biomass. An increase was noted in the density and biomass of the Pyramimonas species in the polluted waters near the sewage water outlets in the Amurskii and Golden Horn bays.     

The trophic position of the alien crab <Emphasis Type="Italic">Rhithropanopeus harrisii</Emphasis> (crustacea decapoda panopeidae) in the Taman Bay,Sea of Azov community

This work concerns the trophic web positioning of the alien crab Rhithropanopeus harrisii and other common marine invertebrate species and fishes in the benthic ecosystem of the shallows of Taman Bay, Sea of Azov. The base of the trophic web in this system is composed of phytoplankton, macrophytes (algae and marine grasses), and reeds that use atmospheric carbon for photosynthesis. Analysis of the isotopic composition of nitrogen and carbon has shown that although marine grasses are dominating primary producers in the shallows of the bay, primary consumers (such as Cerastoderma glaucum, Porifera gen. sp., Gammarus aequicauda, Deshayesorchestia deshayesii and Idotea balthica) only partially use this organic source; instead, they use a combination of different sources of primary production. It has been shown that the food source of the alien crab is primarily of animal origin. In Taman Bay, R. harrisii is on the same trophic level as other carnivores/scavengers: benthic fishes Syngnathus nigrolineatus, Gobius spp. and native crab Pilumnus hirtellus and shrimp Palaemon adspersus.     

Structure of plankton phytocoenoses in the shelf waters of the northeastern Black Sea during the <Emphasis Type="Italic">Emiliania huxleyi</Emphasis> bloom in 2002–2005

It is shown that, in 2002–2005, the mass development of the coccolithofore Emiliania huxleyi on the Gelendzhik shelf occurred annually and in May–June its abundance reached 1.5 × 10⁶ cells/l. In 2004–2005, the bloom of E. huxleyi was accompanied by a mass development of the diatom alga Chaetoceros subtilis var. abnormis f. simplex (0.6–0.9 × 10⁶ cells/l); for the first time, it was registered as a dominating form of the Black Sea phytoplankton. Small flagellates and picoplankton algae played a noticeable role in the phytoplankton throughout the entire period of the studies. Meanwhile, in the early summer period, the bulk of the biomass consisted of coccolithophores (50–60%), while, in the late summer period, diatomaceous algae dominated (50–70%). Among the ecological factors that favor the coccolithophore development one may note the microstratification of the upper mixed layer at a high illumination level and high temperature in the surface waters (18–21°C). The terrigenous runoff during the rainy period had a negative effect on the E. huxleyi development, while storms dispersed the population over the upper mixed layer. The wind-induced near-shore upwelling stimulated the development of diatoms.     

Measuring chlorophyll <Emphasis Type="Italic">a</Emphasis> concentrations in the Sea of Japan using probe and flow fluorimeters

The spatial variability of chlorophyll a concentrations was studied from the data of two near-shore expeditions and the cruise of the R/V Akademik M.A. Lavrent’ev in October–November 2010 over the northwestern part of the Sea of Japan. The sections across eddies showed a maximum of chlorophyll a at a depth of 40 m. According to the data from the cruise, the chlorophyll a concentration was maximum in the north of the sea and decreased to the south. In parallel, the procedures for chlorophyll a determination were compared for spectrophotometry with a fluorescence probe and a fluorescence flow system. The probe data of chlorophyll a fluorescence showed a high correlation with the chlorophyll a concentrations by spectrophotometry. On the contrary, data on chlorophyll a concentrations from spectrophotometry did not agree with those from the flow system. It was shown that a fluorimeter in the flow system recorded dissolved organic matter along with the chlorophyll a fluorescence.     

基于浮游植物吸收的海洋初级生产力模型的不确定性分析

Satellite-derived phytoplankton pigment absorption(a_(ph)) has been used as a key predictor of phytoplankton photosynthetic efficiency to estimate global ocean net primary production(NPP). In this study, an a_(ph)-based NPP model(Ab PM) with four input parameters including the photosynthetically available radiation(PAR), diffuse attenuation at 490 nm(K_d(490)), euphotic zone depth(Z_(eu)) and the phytoplankton pigment absorption coefficient(a_(ph)) is compared with the chlorophyll-based model and carbon-based model. It is found that the Ab PM has significant advantages on the ocean NPP estimation compared with the chlorophyll-based model and carbonbased model. For example, Ab PM greatly outperformed the other two models at most monitoring sites and had the best accuracy, including the smallest values of RMSD and bias for the NPP estimate, and the best correlation between the observations and the modeled NPPs. In order to ensure the robustness of the model, the uncertainty in NPP estimates of the Ab PM was assessed using a Monte Carlo simulation. At first, the frequency histograms of simple difference(δ), and logarithmic difference(δ~(LOG)) between model estimates and in situ data confirm that the two input parameters(Z_(eu) and PAR) approximate the Normal Distribution, and another two input parameters(a_(ph) and K_d(490)) approximate the logarithmic Normal Distribution. Second, the uncertainty in NPP estimates in the Ab PM was assessed by using the Monte Carlo simulation. Here both the PB(percentage bias), defined as the ratio of ΔNPP to the retrieved NPP, and the CV(coefficient of variation), defined as the ratio of the standard deviation to the mean are used to indicate the uncertainty in the NPP brought by input parameter to Ab PM model. The uncertainty related to magnitude is denoted by PB and the uncertainty related to scatter range is denoted by CV.Our investigations demonstrate that PB of NPP uncertainty brought by all parameters with an annual mean of5.5% covered a range of –5%–15% for the global ocean. The PB uncertainty of Ab PM model was mainly caused by a_(ph); the PB of NPP uncertainty brought by a_(ph) had an annual mean of 4.1% for the global ocean. The CV brought by all the parameters with an annual mean of 105% covered a range of 98%–134% for global ocean. For the coastal zone of Antarctica with higher productivity, the PB and CV of NPP uncertainty brought by all parameters had annual means of 7.1% and 121%, respectively, which are significantly larger than those obtained in the global ocean. This study suggests that the NPPs estimated by Ab PM model are more accurate than others, but the magnitude and scatter range of NPP errors brought by input parameter to Ab PM model could not be neglected,especially in the coastal area with high productivity. So the improving accuracy of satellite retrieval of input parameters should be necessary. The investigation also confirmed that the SST related correction is effective for improving the model accuracy in low temperature condition.