Carbon and nitrogen primary productivity in three North Carolina estuaries     

T. R. Fisher  P. R. Carlson  R. T. Barber 《Estuarine, Coastal and Shelf Science》1982,15(6)

Uptake of inorganic carbon and ammonium by the plankton community of three North Carolina estuaries was measured using ¹⁴C and ¹⁵N isotope methods. At 0% light, C appeared to be lost via respiration, and at increasing light levels uptake of inorganic carbon increased linearly, saturated (mean I_k = 358±30 μEin m⁻² s⁻¹), and frequently showed inhibition at the highest light intensities. At 0% light NH₄⁺ uptake was significantly greater than zero and was frequently equivalent to uptake in the light (light independent); at increasing light levels NH₄⁺ uptake saturated (mean I_k = 172±44 μEin m⁻² s⁻¹) and frequently indicated strong inhibition. Light-saturated uptake rates of inorganic carbon and NH₄⁺ were a function of chlorophyll a (r² = 0·7−0·9); average assimilation numbers were 625 nmol CO₂ (μg chl. a)⁻¹ h⁻¹ and 12·9 nmol NH₄⁺ (μg chl. a)⁻¹ h⁻¹ and were positively correlated with temperature (r² = 0·3−0·7). The ratio of dark to light-saturated NH₄⁺ uptake tended to be near 1·0 for large algal populations at low NH₄⁺ concentrations, indicating near light independence of uptake; whereas the ratio was lower for the opposite conditions. These data are interpreted as indicative of nitrogen stress, and it is suggested that uptake of NH₄⁺ deep in the euphotic zone and at night are mechanisms for balancing the C:N of cellular pools. A 24-h study using summed short-term incubations confirmed this; the cumulative C:N of CO₂ and NH₄⁺ uptake during the daylight period was 10–20, whereas over the 24-h period the ratio was 6 due to dark NH₄⁺ uptake. Annual carbon and nitrogen primary productivity were respectively estimated as 24 and 4·0 mol m⁻² year⁻¹ for the South River estuary, 42 and 7·3 mol m⁻² year⁻¹ for the Neuse River estuary, and 9·6 and 1·6 mol m⁻² year⁻¹ for the Newport River estuary.  相似文献   

Using external information and GAMs to improve catch-at-age indices for North Sea plaice and sole   总被引：2，自引：0，他引：2  

Piet  G. J. 《ICES Journal of Marine Science》2002,59(3):624-632

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Diel dynamics of acoustic measurements of Baltic fish     

Orlowski  A. 《ICES Journal of Marine Science》2000,57(4):1196-1203

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千岛湖蚤状溞垂直分布格局及其季节与昼夜变化   总被引：3，自引：0，他引：3  

朱爱娇  姚建良  薛俊增 《海洋湖沼通报》2007,(4)

2004年10月至2005年8月,对不同季节千岛湖蚤状溞的垂直分布情况以及昼夜迁移进行了研究。结果表明,蚤状溞在千岛湖分布广泛,春季和夏季蚤状溞主要分布在15-25m水层,而在秋冬季分布相对均匀,从表层到60m水深都有分布;比较了蚤状溞在不同季节的迁移现象,春季和秋季蚤状溞为夜间迁移模式,而在夏季和冬季虽然都存在迁移现象,但不同于常见的三种迁移模式。  相似文献   

盐度日节律性连续变化对孔石莼生长和生化组成的影响   总被引：2，自引：0，他引：2  

王巧晗  董双林  田相利  王芳 《中国海洋大学学报(自然科学版)》2007,37(6):911-915

利用实验生态学的方法,探讨盐度日节律性连续变化对孔石莼(Ulva pertusa)生长和生化组成的影响,旨在查明潮间带大型海藻对盐度日节律性连续变化的适应性.实验共设5个盐度日节律变化处理(30±3,30±6,30±9,30±12和30±15)和1个恒盐(30±0)对照处理.实验结果表明孔石莼能够耐受较大范围的盐度日节律性连续变化,这种变化虽然对孔石莼的生长不利,但是仍然能够使孔石莼的相对生长率保持在12%以上;盐度变化幅度±3～±15与恒盐对照相比明显不利于孔石莼的生长,盐度变化幅度越大,孔石莼生长越缓慢.同恒盐处理相比,盐度日节律连续变化对孔石莼叶绿素含量的影响不明显,但叶绿素a和叶绿素b含量都有随着盐度变化幅度的增大而逐渐减少的趋势.盐度日节律性连续变化使孔石莼蛋白质和可溶性糖的相对含量显著增加(P＜0.05),随着盐度变化幅度的增大,蛋白质和可溶性糖增加的趋势越明显,并且在盐度日节律性连续变化下,蛋白质增加的速度比可溶性糖增加的速度要快.同时,游离脯氨酸的相对含量随着盐度变化幅度的增加而增加,但是在缓和的盐度日节律性连续变化下(30±3)孔石莼游离脯氨酸的含量却显著小于恒盐对照组(P＜0.05).盐度日节律性连续变化同恒定盐度相比,虽不利于孔石莼的生长,却促进了孔石莼生化产物的合成,是海藻干露时品质得以提高的原因之一.  相似文献   

Fish utilization of a salt marsh intertidal creek in the Yangtze River estuary, China   总被引：6，自引：0，他引：6  

Binsong Jin  Cuizhang Fu  Junsheng Zhong  Bo Li  Jiakuan Chen  Jihua Wu   《Estuarine, Coastal and Shelf Science》2007,73(3-4):844-852

The structure and temporal variations of the fish community in salt marshes of Chinese estuaries are poorly understood. Fish utilization of a salt marsh intertidal creek in the Yangtze River estuary was studied based on quarterly sampling surveys in July and November, 2004, and February and May, 2005. Fishes were collected by consecutive day and night samplings using fyke nets during the ebbing spring tides. A total of 25,010 individuals were caught during the study. 17 families and 33 species were documented, and the most species-rich family was Gobiidae. Three species, Synechogobius ommaturus, Chelon haematocheilus and Lateolabrax maculatus together comprised 95.65% of the total catch, which were also the most important commercial fishery species in the Yangtze River estuary. The fish community was dominated by juvenile individuals of estuarine resident species. Time of year significantly affected fish use of salt marshes, but no significant effects of diel periodicity on the fish community were found except for fish sampling in July. These findings indicate that salt marshes in the Yangtze River estuary may play important nursery roles for fish community.  相似文献   

Field observations of the daily pattern of spawning in the western stock of mackerel (Scomber scombrus L.)     

Nichols  J. H.; Warnes  S. 《ICES Journal of Marine Science》1993,50(2):219-225

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Modelling trace metal concentration distributions in estuarine waters   总被引：2，自引：1，他引：2  

Yan Wu  Roger Falconer  Binliang Lin 《Estuarine, Coastal and Shelf Science》2005,64(4):699-709

The concentration of dissolved organic carbon (DOC) was measured every few months from September 2000 through October 2001 at a coastal location in the center of Suruga Bay, Japan (34°51′N, 138°38′E). Water samples were collected three times per day (midday, night and predawn). DOC concentrations ranged from 91.3 to 45.2 μM C on the surface to 100 m depth. Diel variation in DOC concentrations, among the three sampling times, was greater in the upper 20 m, with a maximum difference of 21.7 μM C in July 2001, and reflected in diel DOC inventory variations from the surface to 50 m. Diel variations were controlled by both physical and biological factors. DOC concentrations were significantly correlated with potential density in the deeper layers (100–1000 m), indicating that the distribution of DOC concentrations in the deeper layer was mainly due to mixing. Most DOC concentrations in the upper layer (0–50 m) did not display the same relationship as in the deeper layer. Using the relationship with potential density at 100–1000 m, the DOC concentration in the upper layer, due simply to mixing, was calculated. The difference between the calculated and observed DOC was used to estimate biological contribution. The biological contributions to the DOC inventory in the upper layer (0–50 m) were found greatly in November 2000 and April 2001. This indicates that excess DOC accumulated, by biological processes, in the upper layer during these periods. In November 2000, the excess DOC in the inventory was constant throughout the sampling days (0.36–0.37 mol C m⁻²), whereas diel variations of DOC in the vertical profile were large and contrary to the variation between 10 and 20 m. This suggests that the excess DOC was contributed biologically during daytime in the uppermost layer and reached to the 50 m depth by deeper mixing. As a result, the inventory appeared to be stable over a day because of the compensating effects of DOC production and consumption throughout 50 m. In contrast, in spring and summer, there was a distinct diel inventory decrease in the nighttime, with apparent rates ranging from −0.61 to −0.35 μM C h⁻¹. It is probable that the DOC, which accumulated during the daytime, was mostly labile, with a turnover time of a few hours. The results indicate that the dynamics of diel DOC variations varied seasonally, and suggest that these variations need to be considered when estimating seasonal DOC pools in the coastal ocean.  相似文献   

The importance of incorporating diurnally fluctuating stream discharge in stream temperature energy balance models          下载免费PDF全文

Emily A. Baker  Laura K. Lautz  Christa A. Kelleher  Jeffrey M. McKenzie 《水文研究》2018,32(18):2901-2914

Although stream temperature energy balance models are useful to predict temperature through time and space, a major unresolved question is whether fluctuations in stream discharge reduce model accuracy when not exactly represented. However, high‐frequency (e.g., subdaily) discharge observations are often unavailable for such simulations, and therefore, diurnal streamflow fluctuations are not typically represented in energy balance models. These fluctuations are common due to evapotranspiration, snow pack or glacial melt, tidal influences within estuaries, and regulated river flows. In this work, we show when to account for diurnally fluctuating streamflow. To investigate how diurnal streamflow fluctuations affect predicted stream temperatures, we used a deterministic stream temperature model to simulate stream temperature along a reach in the Quilcayhuanca Valley, Peru, where discharge varies diurnally due to glacial melt. Diurnally fluctuating streamflow was varied alongside groundwater contributions via a series of computational experiments to assess how uncertainty in reach hydrology may impact simulated stream temperature. Results indicated that stream temperatures were more sensitive to the rate of groundwater inflow to the reach compared with the timing and amplitude of diurnal fluctuations in streamflow. Although incorporating observed diurnal fluctuations in discharge resulted in a small improvement in model RMSE, we also assessed other diurnal discharge signals and found that high amplitude signals were more influential on modelled stream temperatures when the discharge peaked at specific times. Results also showed that regardless of the diurnal discharge signal, the estimated groundwater flux to the reach only varied from 1.7% to 11.7% of the upstream discharge. However, diurnal discharge fluctuations likely have a stronger influence over longer reaches and in streams where the daily range in discharge is larger, indicating that diurnal fluctuations in stream discharge should be considered in certain settings.  相似文献   

Diel activity and short‐distance movement pattern of the European spiny lobster,Palinurus elephas,acoustically tracked          下载免费PDF全文

Vincenzo M. Giacalone  Alberto Barausse  Michele Gristina  Carlo Pipitone  Valerio Visconti  Fabio Badalamenti  Giovanni D'Anna 《Marine Ecology》2015,36(3):389-399

This paper presents the results of the application of an ultrasonic telemetry system to the investigation of short‐term movements in the European spiny lobster, Palinurus elephas, in a coastal area of NW Sicily (Central Mediterranean Sea). Ten lobsters were tagged with miniaturized transmitters and released over a favourable habitat and their movements then recorded by means of nine automated receivers with the objective of investigating post‐release displacement, home‐range extension, movement patterns, activity rhythm and the influence of lunar light intensity on lobster activity. Acoustic detection data were used to assess activity and home range using estimates of horizontal and vertical movements and minimum convex polygons, respectively. Continuous wavelet transform (CWT) analysis was applied to time series of position data. Acoustic data from five of 10 lobsters were successfully recorded across a 78‐day study period between April and June 2008. All of them displayed an activity pattern characterized by diurnal sheltering and nocturnal foraging, with higher activity (i.e., longer distances travelled) at night. Their home range measured between 1629 and 8641 m², and all lobsters relocated every 4.6 days on average, probably in search of unexploited feeding grounds. For this reason we hypothesize a nomadic movement pattern for our tagged lobsters. CWT analyses highlighted a 24‐h periodicity in lobster activity, with higher activity from sunset to sunrise. No clear influence of moon phase on lobster activity was detected.  相似文献