Effects of temperature on growth,photophysiology, Rubisco gene expression in <Emphasis Type="Italic">Prorocentrum donghaiense</Emphasis> and <Emphasis Type="Italic">Karenia mikimotoi</Emphasis>

To explore the effects of temperature changes on dinoflagellate bloom succession in the coastal waters of the East China Sea, changes in the growth, photophysiology, and Rubisco gene expression of Prorocentrum donghaiense and Karenia mikimotoi, two harmful algal species, were investigated at different temperatures (16 to 28°C). The maximal specific growth rate and the maximal mRNA expression of Rubisco gene in P. donghaiense and K. mikimotoi occurred at 20 and 24°C, respectively. The photosynthetic activity of P. donghaiense was generally stable, but K. mikimotoi photosynthesis increased when temperatures rose from 16 to 28°C. The effective photochemical efficiency (F _q ^′ /F _m ^′ ) and the maximal relative electron transfer rate (rETR_max) of K. mikimotoi increased significantly with increasing temperature, and the lowest and highest values occurred at 16 and 28°C, respectively. It seems that P. donghaiense has higher photosynthetic capacity than K. mikimotoi due to its higher F _q ^′ /F _m ^′ , rETR_max, and photosynthetic efficiency (α). However, K. mikimotoi has a higher growth rate than P. donghaiense. These results suggest that the photosynthetic activity and genetic responses of dinoflagellates are species-dependent. It is likely that temperature changes affect species composition during blooms, leading to the observed patterns of bloom succession.     

Feeding,egg production,and respiration rate of pteropods <Emphasis Type="Italic">Limacina</Emphasis> in Arctic seas

The feeding, egg production, and respiration rate of the dominant pteropod Limacina helicina have been studied in Russia’s Arctic seas. The sinking rates of fecal pellets and dead individuals have been measured to estimate their role in vertical carbon flux. As has been shown, the rate of ecophysiological processes taking place in the pteropods is higher than that of copepods, the main consumers of phytoplankton. The gut pigment content in Limacina (3084 ng ind^–1 as a maximum) was two orders of magnitude higher than in copepods. The egg production rate in Limacina even without feeding reached 4000 eggs ind^–1 versus 350–450 egg ind^–1 typical of the dominant copepods even with excess food. A close correlation between the pteropod feeding rate and individual body weight was observed for Limacina rather than a correlation with food concentration. The experimentally estimated sinking rate of Limacina fecal pellets was 270 m day^–1, higher than for most copepods. The sinking rate of dead pteropods reaches 2000 m day^–1. According to the literature, discarded mucous feeding nets sink at a rate of 80 to 1080 m day^–1. Evidently, pteropods play a significant role in biogeochemical cycles by accelerating sedimentation. High rates of all studied processes suggest that Limacina are an important component of plankton communities and play the most important role in trophodynamics at sites of their accumulation.     

春季长江口富营养化水域浮游植物群集对冲淡水和上升流的响应

A comprehensive study on the phytoplankton standing stocks, species composition and dominant species in the eutrophic Changjiang(Yangtze River) Estuary(CE) was conducted to reveal the response of phytoplankton assemblage to Changjiang Diluted Water(CDW) and upwelling in the spring. Phytoplankton presented peak standing stocks(13.03 μg/L of chlorophyll a, 984.5×103 cells/L of phytoplankton abundance) along the surface isohaline of 25. Sixty-six species in 41 genera of Bacillariophyta and 33 species in 19 genera of Pyrrophyta were identified, as well as 5 species in Chlorophyta and Chrysophyta. Karenia mikimotoi was the most dominant species, followed by Prorocentrum dentatum, Paralia sulcata, Pseudo-nitzschia delicatissima and Skeletonema costatum. A bloom of K. mikimotoi was observed in the stratified stations, where the water was characterized by low nitrate, low phosphate, low turbidity, and specific ranges of temperature(18–22 °C) and salinity(27–32). K.mikimotoi and P. dentatum accumulated densely in the upper layers along the isohaline of 25. S. costatum was distributed in the west of the isohaline of 20. Benthonic P. sulcata presented high abundance near the bottom,while spread upward at upwelling stations. CDW resulted in overt gradients of salinity, turbidity and nutritional condition, determining the spatial distribution of phytoplankton species. The restricted upwelling resulted in the upward transport of P. sulcata and exclusion of S. costatum, K. mikimotoi and P. dentatum. The results suggested that CDW and upwelling were of importance in regulating the structure and distribution of phytoplankton assemblage in the CE and the East China Sea.     

Thermal effects on the growth and fatty acid composition of four harmful algal bloom species: Possible implications for ichthyotoxicity

Little is known regarding how harmful algal bloom species respond to different temperatures in terms of fatty acid production. This study examined the effects of temperature on the growth rates, cell volumes, and fatty acid concentrations and compositions of four harmful algal bloom species (HABs), Akashiwo sanguinea, Alexandrium tamarense, Chattonella ovata, and Prorocentrum minimum. The HABs species were cultured at 15, 20, 25, and 30°C in a nutrient-enriched medium. Three of the species maintained optimal growth rates over a wide range of temperatures, but A. tamarense did not. The cell volumes of each species showed little change over the temperature range. The total fatty acid concentrations in A. sanguinea, A. tamarense and C. ovata decreased as the temperature increased, but P. minimum showed no trend in this respect. Polyunsaturated fatty acids (PUFAs), the key biochemical components that maintain cell membrane fluidity and which are associated with toxicity, decreased in both concentration and proportion of total fatty acids as temperature increased, except in A. sanguinea, in which the proportion of PUFAs to the total fatty acids increased. These reductions in PUFA concentration and proportion could reduce cell membrane fluidity and toxicity in HABs; however, enhanced growth and/or ruptured cells, which are considered more toxic than intact cells, could compensate for the reduced per-cell toxicity. This phenomenon might impact on the marine ecosystem and aquaculture industry.     

A new formula for saturated water steam pressure within the temperature range −25 to 220°C

Instead of approximation formula ln(E(t)/E(0)) = [(a ? bt)t/(c + T)] commonly used at present for representing dependence of pressure of saturated streams of liquid water E upon temperature we suggested new approximation formula of greater accuracy in the form ln(E(t)/E(0)) = [(A ? Bt + Ct ²)t/T], where t and T are temperature in °C and K respectively. For this formula with parameters A = 19.846, B = 8.97 × 10^?3, C = 1.248 × 10^?5 and E(0) = 6.1121 GPa with ITS-90 temperature scale and for temperature range from 0°C to 110°C relative difference of approximation applying six parameter formula by W. Wagner and A. Pruß 2002, developed for positive temperatures, is less than 0.005%, that is approximately 15 times less than accuracy obtained with the firs formula. Increase of temperature range results in relative difference increasing, but for even temperature range from 0°C to 220°C it does not higher than 0.1%. For negative temperatures relative difference between our formula and a formula of D. M. Murphy and T. Koop, 2005, is less than 0.1% for temperatures higher than ?25°C. This paper also presents values of coefficients for approximation of Goff and Grach formula recommended by IMO. The procedure of finding dew point T _d for known water steam pressure e _n based on our formula adds up to solving an algebraic equation of a third degree, which coefficients are presented in this paper. For simplifying this procedure this paper also includes approximation ratio applying a coefficient A noted above, in the form T _d (e _n ) = \(\frac{{AT_0 }}{{A - \varepsilon }}\) + 0.0866?² + 0.0116?^10/3, where ? = ln(e _n /E(T ₀)). Error of dew point recovery in this ratio is less than 0.005 K within the range from 0 to 50°C.     

Reproductive biology of blood cockle <Emphasis Type="Italic">Anadara granosa</Emphasis> (Bivalvia: Arcidae) in the northern region of the Strait of Malacca

A study on the reproductive cycle of the blood cockle Anadara granosa (Bivalvia: Arcidae) was conducted at three different areas in the northern region of the Strait of Malacca. A total of 1,920 samples of adult A. granosa (38–71 mm length) were collected from June 2009 until September 2010. Qualitative techniques (gonadal microscopic fresh smear test and histology analysis) as well as quantitative techniques (analysis of condition index and gonadal index) were used to predict monthly gonadal development stages of A. granosa. The gonadal index of A. granosa from Banda Aceh (Indonesia) (r = 0.469, P > 0.05) and Pulau Pinang (Malaysia) (r = 0.123, P > 0.05) did not show any correlation to their condition index, whereas the gonadal index of A. granosa from Lhokseumawe (Indonesia) (r = 0.609, P < 0.05) showed moderate positive correlation to the condition index. During the 16 month sampling period, four reproductive cycles were observed: each from three to six months. The process of releasing gametes is termed dribble spawning, and is the same in all populations. The principle component analysis (PCA) indicated that A. granosa reproduction was affected by interaction between internal physiological factors and indigenous environmental factors. In all sampling areas, phytoplankton density played a key role in the reproductive cycle in A. granosa. Information on the reproductive biology of this species is essential for species management and to improve the sustainability practices of the fisheries industry. These findings will provide basic information on the biology of the blood cockle A. granosa for stock management in the region.     

Morphological characteristics and distribution of Pleuronectidae (Pisces) eggs in the western margin of the East Sea

Seven species of Pleuronectidae (Platichthys stellatus, Kareius bicoloratus, Pseudopleuronectes herzensteini, Microstomus achne, Glyptocephalus stelleri, Hippoglossoides dubius, and Limanda punctatissima) were identified based on eggs collected from the western margin of the East Sea (east coast of Korea), using DNA barcoding. The eggs of P. herzensteini and G. stelleri were relatively widely distributed along the east coast of Korea, whereas those of P. stellatus and K. bicoloratus were narrowly distributed; in particular, the eggs of P. stellatus were restricted to areas near bays. The eggs, which share common morphological characteristics (such as a homogeneous yolk and smooth membrane) were divided into three groups according to egg size: group A (more than 1.60 mm in egg diameter, including genera Hippoglossoides and Microstomus), group B (1.00–1.60 mm, including genera Kareius, Glyptocephalus, and Platichthys), and group C (less than 1.00 mm, including genera Limanda and Pseudopleuronectes). This paper provides an overview of the morphological characteristics of the eggs of the family Pleuronectidae collected from the east coast of Korea. Our approach to the analysis of eggs, based on DNA barcoding, morphological characteristics, and geographic distributions, provides a rapid and accurate basis for identifying spawning areas and spawning periods, thus facilitating the assessment and management of fisheries stocks and resources.     

High mortality and poor growth of green mussels, <Emphasis Type="Italic">Perna viridis</Emphasis>, in high chlorophyll-<Emphasis Type="Italic">a</Emphasis> environment

The current study was carried out from May 2014 to April 2015 to estimate the stock status of P. viridis in Marudu Bay. The gonad development was monitored by histological examination, while the population parameters including asymptotic length (L_∞), growth coefficient (K), mortality rate (Z, F and M), exploitation level (E) and recruitment of P. viridis were estimated using the lengthfrequency data. Results of the current study demonstrated that P. viridis in Marudu Bay spawned throughout the year with two major peaks, one in April to May and another one in October to December. The recruitment pattern was continuous with the peak in May to June 2014, which corresponded to the first spawning peak in April. However, no significant recruitment was observed from the second spawning peak due to the difference in spawning timing between male and female populations. The estimated asymptotic length (L_∞), growth coefficient (K), total mortality (Z), natural mortality (M), fishing mortality (F) and growth performance (ф) of P. viridis in Marudu Bay were estimate to be 117 mm, 0.97 yr^-1, 4.39 yr^-1, 1.23 yr^-1, 3.16 yr^-1 and 4.123, respectively. The exponent b of the lengthweight relationship was 2.4 and exploitation level (E) was 0.72. The high mortality, low condition indices and negative allometric of P. viridis in Marudu Bay is caused by a lack of suitable food in the surrounding water.     

Retrieval of total ozone in the mesosphere with a new model of electronic-vibrational kinetics of O<Subscript>3</Subscript> and O<Subscript>2</Subscript> photolysis products

The paper presents a new model of electronic-vibrational kinetics of the products of ozone and molecular oxygen photodissociation in the terrestrial middle atmosphere. The model includes 45 excited states of the oxygen molecules O₂(b ¹, Σ _g ⁺ ,v= 0−2), O₂ (a ¹Δ _g , v= 0−5), and O₂(X ³Σ _g ⁻ , v= 1−35) and of the metastable atom O (¹ D) and over 100 aeronomic reactions. The model takes into account the dependence of quantum yields of the production of O₂(a ¹Δ _g , v= 0−5) in a singlet channel of ozone photolysis in the Hartley band on the wavelength of photolytic emission. Taking account of the electronic-vibrational kinetics is important in retrieval of the vertical profiles of ozone concentration from measured intensities of the Atm and IR Atm emissions of the oxygen bands above 65 km and leads to an increase in the ozone concentration retrieved from the 1.27-μm emission, in contrast to the previous model of pure electronic kinetics. Sensitivity analysis of the new model is made for variations in the concentrations of atmospheric constituents ([O₂], [N₂], [O(³P)], [O₃], [CO₂]), the gas temperature, rate constants of the reactions, and quantum yields of the reaction products. A group of reactions that most strongly affect the uncertainty of ozone retrieval from measured intensities of atmospheric emissions of molecular oxygen O₂(b ¹Σ _g ⁺ , v) and O₂(a ¹Δ _g , v) has been determined. Original Russian Text ? V.A. Yankovsky, V.A. Kuleshov, R.O. Manuilova, A.O. Semenov, 2007, published in Izvestiya AN. Fizika Atmosfery i Okeana, 2007, Vol. 43, No. 4, pp. 557–569.     

The ecological importance of the dwarf seagrass <Emphasis Type="Italic">Zostera japonica</Emphasis> in intertidal areas on the southern coast of Korea

The intertidal seagrass Zostera japonica, which is distributed in the intertidal and shallow subtidal zones, is exposed to nutrients from over-enriched land-based discharge and storm water runoff before they can be washed out to sea. Despite its ecological importance, only a few studies have examined the ecology and physiology of Z. japonica in northeast Asia. In this study, we investigated the productivity and tissue nutrient contents of above- and below-ground tissues to evaluate the potential role of Z. japonica in carbon capture and as a nutrient sink. The average total, above-, and below-ground productivity per shoot was 0.56, 0.34, and 0.21 mg DW shoot^-1 day^-1, respectively. Annual leaf production was 1.5 times higher than annual below-ground production. Estimated annual whole-plant carbon, nitrogen, and phosphorus incorporation based on shoot production and tissue nutrient contents was 312.8 g C m^-2 y^-1, 25.7 g N m^-2 y^-1, and 1.6 g P m^-2 y^-1, respectively. These values were equivalent to 7.8 × 10³ kg C y^-1, 6.4 × 10² kg N y^-1, and 40 kg P y^-1 for all Z. japonica beds in Geoje Bay. This suggests that Z. japonica meadows can incorporate a considerable amount of carbon, nitrogen, and phosphorus in the intertidal zone. High N:P ratios of above- and below-ground tissues suggest that Z. japonica growth is probably limited by phosphorus availability in the study area.     

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.     

温度、盐度和光照对浒苔生长和光合作用的影响

Intensive Pyropia aquaculture in the coast of southwestern Yellow Sea and its subsequent waste, including disposed Ulva prolifera, was speculated to be one of the major sources for the large-scale green tide proceeding in the Yellow Sea since 2007. It was, however, unclear how the detached U. prolifera responded and resumed growing after they detached from its original habitat. In this study, we investigated the growth and photosynthetic response of the detached U. prolifera to various temperature, salinity and irradiance in the laboratory. The photosynthetic rate of the detached U. prolifera was significantly higher at moderate temperature levels(14–27°C)and high salinity(26–32), with optimum at 23°C and 32. Both low(14°C) and highest temperature(40°C), as well as low salinity(8) had adverse effects on the photosynthesis. Compared with the other Ulva species, U. prolifera showed higher saturated irradiance and no significant photoinhibition at high irradiance, indicating the great tolerance of U. prolifera to the high irradiance. The dense branch and complex structure of floating mats could help protect the thalli and reduce photoinhibition in field. Furthermore, temperature exerted a stronger influence on the growth rate of the detached U. prolifera compared to salinity. Overall, the high growth rate of this detached U. prolifera(10.6%–16.7% d~(–1)) at a wide range of temperature(5–32°C) and salinity(14–32) implied its blooming tendency with fluctuated salinity and temperature during floating. The environmental parameters in the southwestern Yellow Sea at the beginning of green tide were coincident with the optimal conditions for the detached U. prolifera.     

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.     

Growth dynamics of the deep-water Asian eelgrass, <Emphasis Type="Italic">Zostera asiatica</Emphasis>, in the eastern coastal waters of Korea

Among the seagrasses that occur along the coast of Korea, Zostera asiatica inhabits the deepest depth; however, to date, there is limited information on its ecology. This study presents the first quantitative data on the seasonal growth dynamics of Z. asiatica in Korea. We measured seasonal growth and morphological characteristics, as well as environmental factors, including underwater irradiance, water temperature, salinity and nutrient concentrations of the water column and sediment pore water, bimonthly from July 2012 to May 2015. Underwater irradiance showed clear seasonal trends, increasing in the spring and summer and decreasing in the fall and winter, ranging from 2.4 ± 0.2 mol photons m^-2 d^-1 in November 2012 to 12.8 ± 1.3 mol photons m^-2 d^-1 in July 2014. Water temperature also followed a strong seasonal trend similar to underwater irradiance, ranging from 9.8 ± 0.1°C in January 2013 to 20.5 ± 0.2°C in September 2013. Nutrient availability fluctuated substantially, but there was no evidence of distinct seasonal variations. Shoot density, biomass, leaf productivity, and morphological characteristics of Z. asiatica exhibited significant seasonal variations: maximum values of these variables occurred in summer, and the minima were recorded in winter. Total shoot density was highest (218.8 ± 18.8 shoots m^-2) in July 2012 and lowest (106.3 ± 6.3 shoots m^-2) in January 2013. Total biomass ranged from 182.6 ± 16.9 g dry weight (DW) m^-2 in January 2015 to 310.9 ± 6.4 g DW m^-2 in July 2014.Areal leaf production was highest (4.9 ± 0.0 g DW m^-2 d^-1) in July 2012 and lowest (1.4 ± 0.2 g DW m^-2 d^-1) in January 2013. The optimum water temperature for the growth of Z. asiatica was between 16-19°C. Growth of Z. asiatica was more strongly correlated with underwater irradiance than water temperature, suggesting that light is the most important factor determining seasonality of Z. asiatica at the study site.     

Virio- and bacterioplankton in the estuary zone of the Ob River and adjacent regions of the Kara Sea shelf

The distribution of structural and functional characteristics of virioplankton in the north of the Ob River estuary and the adjacent Kara Sea shelf (between latitudes 71°44′44″ N and 73°45′24″ N) was studied with consideration of the spatial variations in the number (N _B) and productivity (P _B) of bacteria and water properties (temperature, salinity, density) by analyzing samples taken in September 2013. The number of plankton viruses (N _V), the occurrence of visible infected bacteria cells, virus-induced mortality of bacteria, and virioplankton production in the studied region varied within (214?2917) × 10³ particles/mL, 0.3?5.6% of NB, 2.2?64.4% of P _B, and (6?17248) × 10³ particles/(mL day), respectively. These parameters were the highest in water layers with a temperature of +7.3–7.5°C, salinity of 3.75?5.41 psu, and conventional density (στ) of 2.846?4.144. The number of bacterioplankton was (614?822) × 10³ cells/mL, and the N _V/N _B ratio was 1.1?4.5. A large amount of virus particles were attached to bacterial cells and suspended matter. The data testify to the considerable role of viruses in controlling the number and production of heterotrophic bacterioplankton in the interaction zone of river and sea waters.     

海草凋落叶的溶解有机物的释放及其生物地球化学意义

Dissolved organic matter(DOM) represents a significant source of nutrients that supports the microbial-based food web in seagrass ecosystems. However, there is little information on how the various fractions of DOM from seagrass leaves contributed to the coastal biogeochemical cycles. To address this gap, we carried out a 30-day laboratory chamber experiment on tropical seagrasses Thalassia hemprichii and Enhalus acoroides. After 30 days of incubation, on average 22% carbon(C), 70% nitrogen(N) and 38% phosphorus(P) of these two species of seagrass leaf litter was released. The average leached dissolved organic carbon(DOC), dissolved organic nitrogen(DON) and dissolved organic phosphorus(DOP) of these two species of seagrass leaf litter accounted for 55%, 95% and 65% of the total C, N and P lost, respectively. In the absence of microbes, about 75% of the total amount of DOC, monosaccharides(MCHO), DON and DOP were quickly released via leaching from both seagrass species in the first 9 days. Subsequently, little DOM was released during the remainder of the experiment. The leaching rates of DOC, DON and DOP were approximately 110, 40 and 0.70 μmol/(g·d). Leaching rates of DOM were attributed to the nonstructural carbohydrates and other labile organic matter within the seagrass leaf. Thalassia hemprichii leached more DOC, DOP and MCHO than E. acoroides. In contrast, E. acoroides leached higher concentrations of DON than T. hemprichii, with the overall leachate also having a higher DON: DOP ratio. These results indicate that there is an overall higher amount of DOM leachate from T. hemprichii than that of E. acoroides that is available to the seagrass ecosystem. According to the logarithmic model for DOM release and the in situ leaf litter production(the Xincun Bay, South China Sea), the seagrass leaf litter of these two seagrass species could release approximately 4×10~3 mol/d DOC, 1.4×10~3 mol/d DON and 25 mol/d DOP into the seawater. In addition to providing readily available nutrients for the microbial food web, the remaining particulate organic matter(POM)from the litter would also enter microbial remineralization processes. What is not remineralized from either DOM or POM fractions has potential to contribute to the permanent carbon stocks.     

Evaluation of spatial distribution of turbulent mixing in the central Pacific

A long-term mean turbulent mixing in the depth range of 200–1000 m produced by breaking of internal waves across the middle and low latitudes (40°S–40°N) of the Pacific between 160°W and 140°W is examined by applying fine-scale parameterization depending on strain variance to 8-year (2005–2012) Argo float data. Results show that elevated turbulent dissipation rate (ε) is related to significant topographic regions, along the equator, and on the northern side of 20°N spanning to 24°N throughout the depth range. Two patterns of latitudinal variations of ε and the corresponding diffusivity (K_ρ) for different depth ranges are confirmed: One is for 200–450 m with significant larger ε and K_ρ, and the maximum values are obtained between 4°N and 6°N, where eddy kinetic energy also reaches its maximum; The other is for 350–1000 m with smaller ε and K_ρ, and the maximum values are obtained near the equator, and between 18°S and 12°S in the southern hemisphere, 20°N and 22°N in the northern hemisphere. Most elevated turbulent dissipation in the depth range of 350–1000 m relates to rough bottom roughness (correlation coefficient?=?0.63), excluding the equatorial area. In the temporal mean field, energy flux from surface wind stress to inertial motions is not significant enough to account for the relatively intensified turbulent mixing in the upper layer.     

Physiological and biochemical responses of <Emphasis Type="Italic">Prorocentrum minimum</Emphasis> to high light stress

Prorocentrum minimum is a common bloomforming photosynthetic dinoflagellate found along the southern coast of Korea. To investigate the adaptive responses of P. minimum to high light stress, we measured growth rate, and generation of reactive oxidative species (ROS), superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA) in cultures exposed to normal (NL) and high light levels (HL). The results showed that HL (800 μmol m^?2 s^?1) inhibited growth of P. minimum, with maximal inhibition after 7–9 days. HL also increased the amount of ROS and MDA, suggesting that HL stress leads to oxidative damage and lipid peroxidation in this species. Under HL, we first detected superoxide on day 4 and H₂O₂ on day 5. We also detected SOD activity on day 5 and CAT activity on day 6. The level of lipid peroxidation, an indicator of cell death, was high on day 8. Addition of diphenyleneiodonium (DPI), an NAD(P)H inhibitor, decreased the levels of superoxide generation and lipid peroxidation. Our results indicate that the production of ROS which results from HL stress in P. minimum also induces antioxidative enzymes that counteract oxidative damage and allow P. minimum to survive.     

“海参-对虾”混养海水池塘的食物网结构及营养层级研究

The food sources of aquacultured Apostichopus japonicus and the trophic levels of organisms in a sea cucumber(A. japonicus) and prawn(Penaeus japonica) polyculture system in a saltwater pond in Zhuanghe, Liaoning Province were examined using carbon and nitrogen stable isotopes. Across organisms, δ13C ranged from(–25.47±0.20)‰ to(–16.48±0.17)‰(mean±SD), and δ15N ranged from(4.23±0.49)‰ to(12.44±0.09)‰. The δ13C and δ15N contents of A. japonicus, P. japonica and Fenneropenaeus chinensis were comparatively higher than those of other organisms. Values of δ13C and δ15N revealed that P. japonica, Hemigrapsus sanguineus and Neomysis japonica comprised the largest component of the diet of A. japonicus. The mean trophic level of the organisms in this saltwater pond polyculture system was(2.75±0.08). P. japonica, A. japonicus, F. chinensis,Synechogobius hasta and Neomysis japonica were in the 3rd trophic level(2–3); jellyfish, H. sanguineus and zooplankton were in the 2nd trophic level(1–2); and Enteromorpha prolifera, benthic microalgae, periphyton and suspended matter primarily consisting of phytoplankton, bacteria and humus were in the primary trophic level(0–1).