Estimation of the minimum food requirement using the respiration rate of medusa of Aurelia aurita in Sihwa Lake

We examined the respiration rate of Aurelia aurita medusae at 20 °C and 28 °C to evaluate minimum metabolic demands of medusae population in Sihwa Lake, Korea during summer. While weight specific respiration rates of medusae were constant and irrespective to the wet weight (8?C220 g), they significantly varied in respect to temperatures (p<0.001, 0.11±0.03 mg C g^?1 of medusa d^?1 at 20°C and 0.28±0.11 mg C g^?1 of medusa d^?1 at 28 °C in average, where Q ₁₀ value was 2.62). The respiration rate of medusae was defined as a function of temperature (T, °C) and body weight (W, g) according to the equation, R=0.13×2.62^(T-20)/10 W ^0.93. Population minimum food requirement (PMFR) was estimated from the respiration rate as 15.06 and 4.86 mg C m^?3 d^?1 in June and July, respectively. During this period, increase in bell diameter and wet weight was not significant (p=1 in the both), suggesting that the estimated PMFR closely represented the actual food consumption in the field. From July to August, medusae grew significantly at 0.052 d-1, thus the amount of food ingested by medusae population in situ was likely to exceed the PMFR (1.27 mg C m^?3 d^?1) during the period. In conclusion, the medusae population of higher density during June and July had limited amount of food, while those of lower in July and August ingested enough food for growth.     

光周期对罗氏沼虾幼体生长及能量收支的影响

于１９９５年２－５月,在Ｌ：Ｄ为４：２０,８：１６,１２：１２和２４：０四种光周期条件下,用卤虫无节幼体作饵料增减罗氏沼虾幼体,测定其生长能量收支。结果表明,随着光照时间的延长幼体生长率增大,两者关系为：ｇ＝６．５２４５＋３．６０４５ｌｎＴ,但周期对幼体Ｃ,Ｎ含量和Ｃ：Ｎ值没有显著的影响;     

Variation of the partial pressure of CO2 in surface water from Kuroshio to Oyashio and the relation between environmental factors and the partial pressure at 144°E off Sanriku, northwestern North Pacific in May, 1997

Partial pressure of CO₂ in surface sea water (pCO₂) was measured continuously off Sanriku in May, 1997 by a new pCO₂ measurement system. We have examined the relation of pCO₂ to physical factors such as temperature, salinity and density, chemical and biological factors such as nutrients and carbonate system and chlorophylla. In the Kuroshio region pCO₂ was not correlated to physical, chemical and biological factors in the range of 260 to 290 μatom. In transition water (Tr1) between Kuroshio and the Oyashio second branch, pCO₂ was weakly correlated to physical factors and strongly correlated to nutrients. In transition water (Tr2) between the Oyashio first and second branches, pCO₂ was highly correlated to temperature (SD: 10.9 μatom) and salinity (SD: 8.6 μatom) and also to nutrients. In transition water (Tr1+Tr2), pCO₂ was highly multivariately correlated to temperature (T), salinity (S), chlorophylla (CH) (or nitrate+nitrite (N)) as follows, pCO₂(μatom)= 10.8×T(°C)+27.7×S+2.57CH(μg/1) −769, R²= 0.86, SD = 20.9, or pCO₂(μatom)= 3.9×T(°C)+25.5×S+16.0NO₃(μM) −686, R²= 0.99, SD = 6.4. Moreover, pCO₂ was predicted by only two factors, one physical (S) and the other chemical/biological (N) as follows: pCO₂ (μatom)=32.8×S+19.4N−908, R²=0.97, SD=8.4. The pH measured at 25°C was well correlated with normalized pCO₂ at a fixed temperature. In the Oyashio region pCO₂ was decreased to 160 μatom, probably because of spring bloom, but was not correlated linearly to chlorophylla. The results obtained showed the possibility of estimating pCO₂ of the Oyashio and transition regions in May by satellite remote sensing of SST, but the problem of estimation of pCO₂ in Kuroshio water remains to be solved.     

长牡蛎F3 代快速生长选育群体生长特性的研究

采用模型拟合方法研究了长牡蛎(Crassostrea gigas)F3代快速生长选育群体不同时期各生长性状的发育规律。结果表明,长牡蛎幼虫期壳高(SH)、壳长(SL)对日龄(t)的回归遵循Logistic模型,生长方程分别为SH=455.612/(1+9.500e-0.142t),R2=0.999;SL=462.476/(1+8.026e-0.108t),R2=0.996。幼虫期壳高与壳长成直线相关,回归方程为SL=0.76SH+18.82,R2=0.994。长牡蛎养成期各生长性状呈现明显的季节变化,壳高(SH)、壳长(SL)、壳宽(SW)和总质量(TW)对月龄(X)的多项式回归方程分别为SH=-0.0297X4+1.0365X3-12.0220X2+57.6500X-68.9260,R2=0.985;SL=-0.0173X4+0.5893X3-6.5702X2+30.2420X-34.4150,R2=0.986;SW=-0.0068X4+0.2620X3-3.2806X2+16.9170X-22.1410,R2=0.956;TW=-0.0219X4+0.8234X3-10.1680X2+50.7040X-85.4110,R2=0.972。壳高、壳长、壳宽与总质量均呈幂函数相关,回归方程分别为SH=23.645TW0.3213,R2=0.998;SL=12.337TW0.3776,R2=0.995;SW=6.611TW0.3589,R2=0.981。     

环境因子对菲律宾蛤仔摄食生理生态的影响

于 1 998年 1— 6月 ,在中国科学院海洋研究所实验室内采用静水方法对采自胶州湾潮间带的菲律宾蛤仔 (以下简称蛤仔 )进行摄食率、清滤率和吸收率的测定。结果表明 :(1 )蛤仔摄食率和清滤率随着个体体重的增加而增大 ,而单位重量的摄食率和清滤率随个体体重的增加而减小 ,它们之间呈幂函数关系。 (2 )底质对蛤仔摄食生理影响的实验表明 :铺砂可以显著地提高蛤仔的摄食生理指标。 (3)在一定的饵料浓度范围内 ,摄食率和清滤率随着浓度的增加而增大 ,呈幂函数关系。当饵料浓度达到一定值后 ,清滤率迅速下降 ,而摄食率只略微有所下降 ,基本上保持平稳不变。这说明蛤仔可以通过调节清滤率来稳定摄食率。 (4)蛤仔吸收率和饵料浓度及个体大小无明显相关性。 (5)水温 1 5℃ ,投喂小球藻的条件下 ,实验结果显示蛤仔 [壳长 (3.53± 0 .0 2 )cm、软体部干重 (0 .41± 0 .0 2 )g]产生假粪的阈值为2 .1 6mgPOM /L。     

Excretion and respiration rates of the scyphomedusa <Emphasis Type="Italic">Aurelia aurita</Emphasis> from the Inland Sea of Japan

We measured the ammonium excretion, phosphate excretion and respiration rates of the scyphomedusa Aurelia aurita from Ondo Strait, in the central part of the Inland Sea of Japan, at 28 and 20°C. The rates measured at 28°C were converted to those at 20°C using the Q₁₀ values, i.e. 1.56, 1.57 and 2.80, for ammonium excretion, phosphate excretion and respiration rates, respectively. The composite relationships between metabolic rates and wet weight of a medusa (WW, g, range 11–1330 g) at 20°C were expressed by the following allometric equations. For ammonium excretion rate (N, μmoles N medusa⁻¹d⁻¹): N = 0.497WW ^1.09, phosphate excretion rate (P, μmoles P medusa⁻¹d⁻¹): P = 0.453WW ^0.84, and respiration rate (R, μmoles O₂ medusa⁻¹d⁻¹): R = 96.9WW ^1.06. Mean O:N ratios (i.e. atomic ratios of 16.9 and 11.0 at 28 and 20°C, respectively) indicated that the metabolism of A. aurita medusae was protein-dominated. These metabolic parameters enabled us to estimate the nitrogen and phosphorus regeneration rates of an A. aurita medusa population typical of early summer in the Ondo Strait (means of water temperature, medusa individual weight and population biomass: 20°C, 200 g WW and 50.8 g WW m⁻³, respectively). Regenerated nitrogen and phosphorus were equivalent to 10.0 and 21.6% of phytoplankton uptake rates, respectively, nearly twice that estimated for mesozooplankton, demonstrating that A. aurita medusae are key components of the plankton community, influencing the trophic and nutrient dynamics in the Ondo Strait during early summer.     

Method for comparing fish growth curves

The method of comparing growth curves that is described in this paper consists of describing growth for the ith group by the equation Li(t) = ai + bi r^t, which is linear in the two parameters ai and bi, and subsequently using the analysis of variance to compare the curves. The advantages of the linear growth equation over the von Bertalanffy equation, l i (t) ⁼ ai + bi r^t i, are easier analysis and a much simpler interpretation of the differences in the parameters in terms of growth rate and maximum size. An example comparing the growth of male and female red gurnard Chelidonichthys kumu from four areas within the Hauraki Gulf is given.     

Consumption,absorption efficiency,respiration and excretion in the South African abalone Haliotis midae

Feeding periodicity, consumption rate, absorption efficiency, respiration rate and ammonia excretion were measured as functions of wet body mass in abalone collected from the western and southern Cape coasts. A well developed diel feeding rhythm was evident, consumption being restricted to the period 16h00–08h00. Food intake averaged 8,1 per cent of wet flesh mass·d^?1 at 14°C and 11,4 percent at 19°C. The daily consumption rate was related to body mass by the relationships C(g) = 0,54 W(g)^0,67 at 14°C and C(g) = 0,35 W(g)^0,77 at 19°C. Absorption efficiency averaged 37 per cent and was independent of body size. Equations relating respiration rate to wet body mass were R(m? O₂·h^?1) = 0,03 W(g)^0,83 at 14°C and R = 0,03 W(g)^0,94 at 19°C. No significant differences were detected between day and night rates or between fed and starved individuals. The rate of ammonia excretion (μmole·h^?1) was related to wet body mass (g) by the equations U = 0,22 W^0,43 at 14°C and U = 0,03 W^0,85 at 19°C.     

不同规格近江牡蛎的排氨率和耗氧率分析

采用实验生态学方法研究了不同规格近江牡蛎的呼吸和排泄生理生态学参数。结果显示,近江牡蛎耗氧率R_O随软体干重(W )的增加而减小, 体重对近江牡蛎耗氧率(R_O)的影响达极显著水平,R_O = 1.8232W^-0.7600, (R²= 0.8313 , P <0.01); 近江牡蛎的排氨率(R_N)和排磷率(R_P)随软体干重的增加而降低,呈负相关关系;而氧氮比O/N和氮磷比N/P在各组间未达显著水平(P >0.05) , R_N = 0.0930W^-0.6582 (R² = 0.7444, P <0.01)、R_P = 0.0126W^-0.8874 (R² = 0.9224,P <0.01);各组不同规格近(大小)江牡蛎的O/N值较高,而N/P值则随规格增大而呈上升趋势,但差异也不显著(P >0.05)。这些研究结果对牡蛎养殖密度和环境关系分析及牡蛎健康养殖具有重要参考价值。     

胶州湾菲律宾蛤仔（Ruditapes philippinarum）呼吸排泄作用的现场研究

于2006年2月、5月、8月和11月四个季度月采用呼吸瓶法现场研究了胶州湾菲律宾蛤仔的呼吸排泄作用。结果表明,胶州湾菲律宾蛤仔呼吸排泄速率具有明显的季节变化趋势,春、夏季高于秋、冬季。不同生物学规格的蛤仔呼吸排泄速率具有明显的差异,单位个体耗氧率、排氨率和排磷率均随着个体大小的增加而增加,而单位体重的耗氧率、排氨率和排...     

Relations between fecal pellet volume and body size for major zooplankters of the Inland Sea of Japan

Measurements of fecal pellet volume together with body length/body carbon weight were made for major zooplankters of the Inland Sea of Japan. The pellet volume was highly correlated with animal body size for copepods (10 species combined), a mysid (Neomysis japonica), a larvacean (Oikopleura dioica) and a pelagic shrimp (Acetes japonicus), and a specific equation was given for each group. A single equation could describe the composite relationship between pellet volume (PV, m³) and body carbon weight (C, g) for copepods andN. japonica: logPV=0.85logC+4.56. Balanid nauplii,O. dioica and a doliolidDolioletta gegenbauri produced pellets larger, butA. japonicus produced pellets smaller, than those by copepods andN. japonica of equivalent body carbon weight. In general, larger zooplankters produce larger fecal pellets. Hence, the size composition of the zooplankton community is an important parameter for the variation in the vertical flux of material via fecal pellets.     

Netplankton Chlorophyll Biomass along 175°E in the Pacific Ocean

An analysis is presented of data on chlorophyll a concentrations of the total and the netplankton (>10 μm), determined either in April to June or in August to September from 48°N to 15°S along 175°E in the Pacific Ocean during 6 years by the NOPACCS (Northwest Pacific Carbon Cycle Study). Particular attention was given to the variability of absolute concentrations of the netplankton chlorophyll a and their percentage shares of the total chlorophyll a concentration. Below 0.2 μg l⁻¹ of surface total chlorophyll a, the netplankton chlorophyll a showed low percentage shares (such as 12.7% on average) with a large variation, but above 0.2 μg l⁻¹ it was 35.9% on average with less variation, showing an accelerated increase at high total chlorophyll a concentrations. High netplankton chlorophyll a concentrations in surface waters were observed at high latitudes, in waters having high chlorophyll a concentrations at sub-surface depth, and in equatorial upwelling. The percentage shares of netplankton in the total chlorophyll a in the euphotic zone were 8.5% and 25.9% above and below 0.2 μg l⁻¹, respectively, although the data points scattered over a wide range (from 7.2% to 53.8%) depending on differences in water masses, depths and seasons. High chlorophyll a concentrations and high percentage shares of netplankton corresponded to high ambient nitrate plus nitrite concentrations. Integrated netplankton chlorophyll a concentrations in the euphotic zone varied from 0.7 to 19.5 mg m⁻² in waters below 0.2 μg l⁻¹ of surface total chlorophyll a, and from 2.0 to 29.5 mg m⁻² above 0.2 μg l⁻¹, and the percentage shares of netplankton for the former were 7.4% on average and 23.7% for the latter. This revised version was published online in July 2006 with corrections to the Cover Date.     

Phytoplankton pigment change as a photoadaptive response to light variation caused by tidal cycle in Ariake Bay,Japan

Underwater light environment and photosynthetic accessory pigments were investigated in Ariake Bay in order to understand how change of the pigments occurs in response to the tidal-induced changes in underwater light conditions. We hypothesize that phytoplankton increases photo-protective pigments and decreases light-harvesting pigments under higher light condition in the mixed layer caused by tidal cycle. Contribution rates of non-phytoplankton particles (a _nph (400–700)) for light attenuation coefficient (K _d ) was highest (32–85%), and those of phytoplankton particles (a _ph (400–700)), dissolved organic matter (a _g (400–700)) and water were 6–32, 6–21 and 5–23%, respectively. Mean K _d was higher during the spring tide (0.55 ± 0.23 m⁻¹) than the neap tide (0.44 ± 0.16 m⁻¹), and the K _d difference was caused by the substances resuspension due to the tidal current. In contrast, ratios of photo-protective pigments (diadinoxanthin and diatoxanthin) per chlorophyll a ((DD+DT)/Chl a) were higher during the neap tide (0.10 ± 0.03 mg mg-Chl a ⁻¹) than the spring tide (0.08 ± 0.03 mg mg-Chl a ⁻¹). And there was significant positive correlation between (DD+DT)/Chl a and mean relative PAR in the mixed layer ($ \overline {I_{mix} } $ \overline {I_{mix} } ). Moreover, there was significant negative correlation between ratios of light-harvesting pigments (fucoxanthin) per Chl a (Fuco/Chl a) and $ \overline {I_{mix} } $ \overline {I_{mix} } . These results suggested that phytoplankton in Ariake Bay increase photo-protective pigments and decrease light-harvesting pigments in the higher light condition of less turbid, shallower mixed layer during neap tide than spring tide.     

An evaluation of inversion models for retrieval of inherent optical properties from ocean color in coastal and open sea waters around Korea

This study was aimed to investigate three inversion models (currently in use with Moderate Resolution Imaging Spectroradiometer and Sea-viewing Wide Field-of-view Sensor data processing), namely constrained Linear Matrix (LM), Quasi-analytical algorithm (QAA) and GSM semi-analytical models (GSM). These models were applied to large bio-optical data sets (collected from coastal and open sea waters around Korea) to retrieve inherent optical properties (IOPs) such as absorption coefficients of phytoplankton (a _ph ), colored dissolved and detrital organic matters (a _cdm ), and particulate backscattering coefficient (b _bp ) at five wavelengths (412, 443, 490, 510, and 555 nm). The derived IOP products were compared with in situ a _ph , a _cdm and b _bp coefficients measured for the same remote sensing reflectance (R _rs (λ)) data sets used in the models and the uncertainties of the three models were assessed based on the standard statistical procedures (mean relative error MRE, root mean square error RMSE, slope, and coefficient of determination R ²). It was found that all the three models tended to yield significant errors with varying magnitude at different wavelengths. Overall performance of the models assessed based on the above statistical means was found in the following order: LM > GSM > QAA for retrieving the a _ph , LM > GSM > QAA for retrieving the a _cdm , and QAA > GSM > LM for retrieving the b _bp . Our analyses suggest that these models will require additional refinements with a full parameterization by a fully suited data set in order to produce accurate retrievals of IOPs in coastal and open sea waters around Korea.     

Correlation of chlorophyll concentrations and suspended solids with near-surface upward irradiance within LANDSAT bands 4, 5 and 6

Near-surface upward irradiances within each band of the MSS (multi spectral scanner) of LANDSAT, were computed from observed spectral upward irradiances measured just beneath the sea surface. Computation of these irradiances is a useful first step in the analysis of remotely-sensed radiance because the data are not affected by the effects of the atmosphere and sea surface. The computed irradianceE in LANDSAT bands 4, 5 and 6 was normalized by forming ratios,i.e., R ₄₅=E₄/E₅, R₄₆=E₄/E₆, andR ₅₆=E₅/E₆, and then the relationship between these ratios and chlorophylla plus phaeopigment concentration (C) observed simultaneously at 59 stations was examined by linear regression analysis. The observedC ranged over nearly three orders of magnitude, and there is a close to linear relationship between log₁₀-R ₄₅ and log₁₀ C. This suggests that it may be possible to evaluateC from LANDSAT data, if an appropriate atmospheric correction is made. The relationship between suspended solids determined at 35 stations and the same ratios of upward irradiance is also presented and discussed.     

Picoplankton: Contribution to Phytoplankton Production in the Strait of Messina*

Abstract. Biomass and primary production rates derived from photosynthesis-light curves on picoplankton (< 1 um fraction) and total phytoplankton were compared for the Strait of Messina. Picoplankton biomass ranged between 0.063 and 0.094 mg Chi a m^-5 and accounted for 56–63 % of the total. Total primary production rates were between 0.22 and 1.56 mg C-m^-2-h^-1 of which the picoplankton contribution ranged from 24 to 43%. In this turbulent nearshore environment, the contribution of picoplankton to total phytoplankton production is considerably less than in calmer open-ocean waters. Carbon assimilation numbers (Pm^b), the initial slope (a), adaptation parameter (I_k), optimal irradiance (I_m) and compensation intensity (L_m,) for the picoplankton were lower than for the > 1 μm fraction. Fitted respiration (Rm^B) for the picoplankton was, however, on the average higher (10.3 % of Pm^B) than for the > 1 μrn fraction (6.6 %). Assimilation numbers for the > 1 μm fraction in the southern stations were of higher magnitude (8.5–12.0 mg C mg Chi a^-1 h^-1) than in the northern station, possibly due to the impact of upwelled water flowing southward along the Sicilian coast.     

ADSORPTION ACTION OF BASIC ZINC CARBONATE ADSORBENT ON URANIUM IN NATURAL SEAWATER

1. The adsorption action of basic zinc carbonate adsorbent on uranium in natural seawater can be expressed with the following formula of adsorption isotherm:C=k(U*)n = 8.51× 10-1(U*)0.49,where C is the concentration of uranium on adsorbent; U* is content of uranium in natural seawater employed.2. when the quantity of basic zinc carbonate adsorbent (T) is constant, with the increase of natural seawater quantity through the adsorption column (G), also increased are the adsorption content of uranium of the adsorbent (U), the concentration of uranium on the adsorbent (C) and the concentration of residual uranium (C0*) in natural seawater after adsorbing uranium, while the rate of recovery of uranium (R) is decreased. With the increase of (G) the coefficient of distribution (Kd) decreases to a certain value and then a little rises again.     

Estimated respiration rate of myctophid fish from the enzyme activity of the electron-transport-system

Whole animal respiration rates (R) of myctophid fishes which migrate up to the surface at night were estimated using enzyme activities of the electron-transport-system (ETS). The fish, currently unsusceptible to laboratory experimentation, were caught at sea and stored frozen at –20°C for 14–17 days prior to enzyme assay. Supplemental tests on two tropical marine fishes (gobies and poma-centrids) showed no measurable loss of ETS activity during storage for up to 36 d at –20°C. The ETS/R ratio for gobies and pomacentrids was 1.61. Respiration rates of myctophid fishes estimated using this ETS/R ratio ranged from 17.7 to 453µl O₂ individual^–1 hr^–1 for specimens weighing 26–1101 mg wet weight atin situ temperature of 24–27°C. The relationship between the respiration rate standardized to a temperature of 20°C (R:µl O₂ individual^–1hr^–1) and wet weight (WW: mg) of myctophid fishes was expressed asR=0.790 WW^0.84 (r=0.964,n=27). This relationship does not differ appreciably from the respiration rates of other marine fishes calculated from Winberg's equation.     

Effects of cold eddy on phytoplankton production and assemblages in Luzon strait bordering the South China Sea

The biochemical effects of a cold-core eddy that was shed from the Kuroshio Current at the Luzon Strait bordering the South China Sea (SCS) were studied in late spring, a relatively unproductive season in the SCS. The extent of the eddy was determined by time-series images of SeaWiFS ocean color, AVHRR sea surface temperature, and TOPEX/Jason-1 sea surface height anomaly. Nutrient budgets, nitrate-based new production, primary production, and phytoplankton assemblages were compared between the eddy and its surrounding Kuroshio and SCS waters. The enhanced productivity in the eddy was comparable to wintertime productivity in the SCS basin, which is supported by upwelled subsurface nitrate under the prevailing Northeastern Monsoon. There were more Synechococcus, pico-eucaryotes, and diatoms, but less Trichodesmium in the surface water inside the eddy than outside. Prochlorococcus and Richelia intracellularis showed no spatial differences. Water column-integrated primary production (IPP) inside the eddy was 2–3 times that outside the eddy in the SCS (1.09 vs. 0.59 g C m⁻²d⁻¹), as was nitrate-based new production (INP) (0.67 vs. 0.25 g C m⁻²d⁻¹). INP in the eddy was 6 times that in the Kuroshio (0.12 g C m⁻²d⁻¹). IPP and INP in the eddy were higher than the maximum production values ever measured in the SCS basin. Surface chlorophyll a concentration (0.40 mg m⁻³) in the eddy equaled the maximum concentration registered for the SCS basin and was higher than the wintertime average (0.29 ± 0.04 mg m⁻³). INP was 3.5 times as great and IPP was doubled in the eddy compared to the wintertime SCS basin. As cold core eddies form intermittently all year round as the Kuroshio invades the SCS, their effects on phytoplankton productivity and assemblages are likely to have important influences on the biogeochemical cycle of the region.