Seasonal Variations In Primary Production Research Articles

Seasonal variation of gross ecosystem productivity of periphyton in three post-mining lakes in the Czech Republic, Europe

We investigated the seasonal variation of gross ecosystem productivity (GEP) of periphyton biomass in three post-mining lakes in the Czech Republic. These lakes were established as part of recultivation efforts after coal mining activities and resulted in a unique series of anthropogenic oligotrophic lakes of gradual successional age. Periphyton is ubiquitous in aquatic habitats and performs numerous environmental functions such as nutrient cycling and self-purifying of aquatic ecosystems. Well-developed periphyton mat can be formed within a few weeks, so it can quickly become the dominant of littoral zone of newly established lakes. In studied post-mining lakes, the highly developed periphytic community covers the littoral zone of each lake to the depth of 2m (Bešta et al. 2022, Konopáčová et al. 2023) Fig. 1. We aimed to shed some new light on the processes controlling the dynamics of primary productivity in oligotrophic lakes. The accurate estimation of primary productivity is crucial for understanding the functioning of aquatic ecosystems, as primary productivity serves as the primary source of autochthonous carbon in these systems. In addition to phytoplankton, periphyton can significantly contribute to primary productivity in littoral zones, known for their high productivity and biodiversity. Conducting in situ measurements provides the most accurate means of inferring the metabolic activity of primary producers in littoral zones. We conducted detailed seasonal in-situ periphyton gross primary production (GPP) measurements in three post-mining lakes with different successional ages (Čapková et al. 2022). GPP and NPP of periphytic biomass were determined using direct in-situ measurement of O2 fluxes. O2 production and consumption were measured over 5 hours of in-situ light and dark gas-tight glass bottle incubation. Bottles were filled with the lake water from the corresponding depth, and a similar amount of periphytic biomass was enclosed Fig. 2. We used the Fibox3 fibre-optic oxygen meter coupled with a PSt3 oxygen sensor (PreSens, Regensburg, DE) to measure changes in O2 concentration. The O2 fluxes were normalized to periphytic biomass in each bottle (measured as total organic carbon). Data were corrected for O2 concentration changes in dark and light gas-tight bottles containing lake water without periphytic communities. This setup enabled us to monitor online oxygen flux, therefore, insights into metabolic activities. The primary productivity was measured in real-time, allowing us to capture the quantitative effect of various environmental drivers on periphyton productivity, i.e. phosphorus concentration and light intensity, as they are known to play significant roles in primary productivity. We showed that the primary production of periphyton mats exhibited seasonal variations, with higher productivity observed in spring compared to other seasons. This observation could be attributed to the occurrence of winter/spring upwelling events and vertical mixing, which resupply nutrients from the deeper strata. Furthermore, the physiological activity of periphyton was strongly influenced by the seasonal changes in light intensity, temperature, and nutrient concentration. We provided the first insight into the seasonal variation of primary productivity of the periphyton assemblage dominating the littoral zone of newly established post-mining lakes. We stress the importance of periphyton in aquatic ecosystems, particularly in anthropogenic oligotrophic lakes.

Assessment of seasonal variation in primary productivity of Arjunsagar Reservoir, Uttar Pradesh, India

Assessment of seasonal variation in primary productivity of Arjunsagar Reservoir, Uttar Pradesh, India

A LIMNOLOGICAL STUDY OF PRIMARY PRODUCTIVITY IN SEASONAL VARIATIONS OF A TYPICAL TROPICAL POND OF BUNDELKHAND REGION, INDIA

The primary productivity of the Mahil pond has been estimated from March 2017 to February 2018 at four different stations. Various physicochemical parameters and phytoplankton were studied. The seasonal variation of primary productivity revealed that maximum and minimum values of Gross primary productivity and community respiration were associated with rainy and summer seasons respectively. The minimum values of Net primary productivity were recorded during rainy season and maximum during winterfor different study stations.

Spatial and vertical variability of primary production in the Kara Sea in July and August 2016: the influence of the river plume and subsurface chlorophyll maxima

Seasonal variations in primary production (PP) in the Kara Sea are underresearched. Previous studies only collected data during autumn or in late summer. However, the middle of summer is close to the beginning of the growing season, when PP can contribute significantly to annual water column integrated primary production (IPP). In addition, differences can be expected in the spatial and vertical distribution of phytoplankton communities in this period. This gap in midsummer data was addressed within the framework of a multidisciplinary research cruise by the R/V “Akademik Mstislav Keldysh” (from 15 July to 18 August 2016). High values of IPP (> 200 mgC m−2 day−1) and surface chlorophyll a (Chl a) concentration (Chl0 > 1 mg m−3) were associated with the Ob–Yenisey river plume, located in the central part of the Kara Sea. Beyond the influence of the plume, in the western and southwestern regions of the Kara Sea, well-pronounced subsurface chlorophyll maxima (SCM) were observed. In some cases, the Chl a concentration in SCM exceeded Chl0 by two orders of magnitude. SCM were often accompanied by subsurface PP maxima (SPM). At stations where SCM was pronounced, IPP values reached 500–800 mgC m−2 day−1, and > 30 % of IPP was accounted for by SPM-integrated PP. Thus, in the middle of summer in the Kara Sea, IPP was linked with the chlorophyll-specific phytoplankton biomass and depended on the strength of the SCM.

Biogeochemical versus ecological consequences of modeled ocean physics

Abstract. We present a systematic study of the differences generated by coupling the same ecological–biogeochemical model to a 1°, coarse-resolution, and 1∕6°, eddy-permitting, global ocean circulation model to (a) biogeochemistry (e.g., primary production) and (b) phytoplankton community structure. Surprisingly, we find that the modeled phytoplankton community is largely unchanged, with the same phenotypes dominating in both cases. Conversely, there are large regional and seasonal variations in primary production, phytoplankton and zooplankton biomass. In the subtropics, mixed layer depths (MLDs) are, on average, deeper in the eddy-permitting model, resulting in higher nutrient supply driving increases in primary production and phytoplankton biomass. In the higher latitudes, differences in winter mixed layer depths, the timing of the onset of the spring bloom and vertical nutrient supply result in lower primary production in the eddy-permitting model. Counterintuitively, this does not drive a decrease in phytoplankton biomass but results in lower zooplankton biomass. We explain these similarities and differences in the model using the framework of resource competition theory, and find that they are the consequence of changes in the regional and seasonal nutrient supply and light environment, mediated by differences in the modeled mixed layer depths. Although previous work has suggested that complex models may respond chaotically and unpredictably to changes in forcing, we find that our model responds in a predictable way to different ocean circulation forcing, despite its complexity. The use of frameworks, such as resource competition theory, provides a tractable way to explore the differences and similarities that occur. As this model has many similarities to other widely used biogeochemical models that also resolve multiple phytoplankton phenotypes, this study provides important insights into how the results of running these models under different physical conditions might be more easily understood.

Spatio-temporal variability of the phytoplankton biomass in the Levantine basin between 2002 and 2015 using MODIS products

Summary The Levantine basin in the Eastern Mediterranean Sea is subject to spatial and seasonal variations in primary production and physical-chemical properties both on a short and long-term basis. In this study, the monthly means of daily MODIS product images were averaged between 2002 and 2015, and used to characterize the phytoplankton blooms in different bioregions of the Levantine basin. The selected products were the sea surface temperature (SST), the chlorophyll- a concentration (Chl- a ), the diffuse attenuation coefficient for downwelling irradiance at 490 nm (Kd_490) and the colored dissolved organic matter index (CDOM_index). Our results showed that phytoplankton blooms were spatially and temporally variable. They occurred in late autumn at the Nile Delta, in early spring and late summer at the eastern coastline, and in spring at the northeastern coastline. The northern coastline and the open water had a common bloom occurring in winter. The Nile Delta was found to be the most productive area of the Levantine basin showing high Chl- a . Kd_490 and Chl- a present a parallel co-variation indicating a dominance of Case 1 waters in the Levantine basin. The CDOM_index shows a phase shift with the Chl- a fluctuation. A strong inverse correlation was observed between both Chl- a and CDOM_index with SST, connoting an indirect relation represented by a depression of CDOM in summer by photobleaching, and a suppression of the chlorophyll- a concentration due to water stratification, together with nutrient stress. An overestimation of the Chl- a values had been signaled by the use of the CDOM_index, suggesting a correction plan in a latter study.

Studies on seasonal variations in primary production of river Mahanadi, Banki, Odisha, India

The primary productivity of the river Mahanadi at Banki has been estimated from January 2012 to December 2012 at three different stations. The seasonal variation of primary productivity revealed that maximum and minimum values of GPP was associated with summer and winter seasons respectively. The minimum values of NPP were recorded during rainy season and maximum during summer or winter for different study stations. The community respiration showed a systematic seasonal pattern where the maximum value was observed during summer and minimum value during winter. The ratio between NPP and GPP was lowest during rainy season and highest in summer.

Seasonal variation of primary productivity in the Shinkawa River estuary, eastern Seto Inland Sea, Japan

Seasonal variation of primary productivity in the Shinkawa River estuary, eastern Seto Inland Sea, Japan

Nepheloid layer distribution in the Whittard Canyon, NE Atlantic Margin

article i nfo Article history: The dynamics and distribution of nepheloid layers in multiple branches of the Whittard Canyon were observed during three hydrographic surveys carried out between 2011 and 2013. The sources of permanent and temporal variation of the layers were investigated. Seasonal variations in primary production at the surface were reflected in the nepheloid layers extending down in the water column, particularly in the upper reaches of the canyon. Benthic nepheloid layers were observed along the canyon axes to depths greater than 2500 m, a distance of ~30 km. Intermediate nepheloid layers were detected as lateral extensions of the benthic nepheloid layer, centredat~550m,850m,1150 mand1600m and stretching ~20-25kmoff slope.Criticalandsupercriticalcon- ditions for semidiurnal tide reflection were identified coinciding with the occurrence of intermediate nepheloid layers, with other hotspots found at the boundaries of the permanent thermocline and Mediterranean Outflow Water. Weak seasonal stratification during the survey in 2012 appeared to permit storm induced mixing at deeper water depths than expected, altering the distribution of material in the nepheloid layers. The dynamic conditions of the canyon encourage nepheloid layer formation with implications ensued for deposition rates and food supply to the unique communities that are found in the Whittard Canyon and likely other similar can- yon systems.

Primary production under hypertrophic conditions and its relationship with bacterial production

In shallow hypertrophic lakes where light availability restricts the growth of macrophytes and benthic phytoplankton, pelagic phytoplankton modulates importantly ecosystem production and the energy transfer to heterotrophic bacteria. Diel and seasonal variations in primary production (PP) were studied in the hypertrophic Albufera de Valencia (Spain). Additionally, the relationship between PP and heterotrophic bacterial production (BP) was assessed. PP was extremely high, exceeding most values reported for hypertrophic lakes to date. PP displayed marked diurnal variations defined by the solar radiation curve. Likewise, PP changed importantly across seasons. Minimum PP coincided with maximum water transparency and short water residence times in winter, whereas maximum PP was observed in late spring associated with high chlorophyll a. The spring PP maximum contrasted with the summer maximum often observed in hypertrophic lakes. When compared to spring PP values, summer PP values were lower as a result of strong nitrogen limitation. In contrast to PP, BP remained fairly constant across seasons. Nonetheless, there was a joint diminution during increased water transparency followed by an increase in early spring. Phytoplankton was always the most relevant input to particulate carbon production, but the BP/PP ratio showed clear seasonal variations. The BP/PP ratio was minimum in spring, low in summer and highest in winter. The extracellular dissolved organic carbon released by phytoplankton was sufficient to meet bacterial carbon demand in all experimental dates, suggesting that allochthonous carbon sources play a minor role in sustaining BP, though they cannot be excluded. However, we hypothesize that high availability of dissolved organic carbon might explain the lack of coupling observed between BP and PP.

刺参养殖池塘初级生产力及其粒级结构周年变化

PDF HTML阅读 XML下载 导出引用 引用提醒 刺参养殖池塘初级生产力及其粒级结构周年变化 DOI: 10.5846/stxb201304240801 作者: 作者单位: 盐城师范学院,大连海洋大学,盐城师范学院,大连海洋大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金资助项目（30901107）；国家科技部“863”计划项目（2006AA10Z410）；盐城市农业科技创新专项引导资金项目；江苏省滩涂生物资源与环境保护重点建设实验室开放课题（JLCBE13002） Annual variations of the primary productivity and its size-fractioned structure in culture ponds of Apostichopus japonicus Selenka Author: Affiliation: Yancheng Teachers University,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:研究了刺参（Apostichopus japonicus Selenka）养殖池塘浮游植物初级生产力及粒级结构的周年变化规律，旨在明确刺参养殖池塘的基础生态学特征，为刺参养殖生产和管理提供科学支持。结果表明：刺参养殖池塘初级生产力年平均值为（5.16±3.04）gO2 m-2 d-1，全年呈现明显的季节变化，初级生产量分别在初春、夏季和初冬形成高峰。初级生产力群落净产量占毛产量的 50.2%。P/R值与日P/B系数的年平均值分别为 2.20 ± 1.25 和 0.39 ± 0.35。按初级生产力水平和P/R值划分的水体营养类型，调查刺参养殖池塘属富营养型水体；初级生产量随深度的增加而递减，最高生产层约在透明度的0.5倍处，且0.5倍透明度（约50 cm）以上水层初级生产量占水柱总产量的56.3%；不同粒级浮游植物生产量占总生产量的百分比具有明显的季节变化。除夏季外，以小型浮游植物（micro-，20-200 μm）对初级生产力的贡献最大（43.5%），夏季为微型浮游植物（nano-，2-20 μm）对初级生产力贡献最大（35.3%）。 以年平均值计算，不同粒级浮游植物初级生产量占总生产量百分比的大小顺序为：小型（40.1%）> 微型（28.2%）> 中大型（16.1%）> 超微型（15.7%）。回归分析表明：试验池塘初级生产力水平与水温、营养盐中的氨氮和亚硝酸氮均呈显著的相关关系（P<0.05）。结果提示，刺参养殖池塘初级生产力的季节变化显著，垂直分布并不均匀，小型浮游植物是其生态系统中的主要生产者。 Abstract:During October 2005 to October 2006, the annual variations of the primary productivity (PP) of phytoplankton and its size-fractioned structure in the culture ponds of Apostichopus japonicus Selenka were investigated on the coast of North Yellow Sea, Dalian, Liaoning Province of China. This study aimed to determine the basic ecological characteristics in culture ponds of A. japonicus, provide scientific supports for production and management of A. japonicus culture. The mean area of the experimental ponds was 3.0 hm2 with mean water depth as 1.8 m. Mean seeding density of cultured animals and seed size in the ponds were 49829 ind./hm2 and 1.25 g/ind. During the experiment seawater temperature varied from -1.4 to 26.5 ℃, salinity 25.5 to 34.5‰, pH 7.56 to 8.23, transparency 0.2 to 1.8 m and annual mean value of NH4+-N was (0.05 ± 0.03) mg/L. PP was estimated by dark and light bottles method. The depths of suspending bottles were generally 20 cm (surface layer), 0.5 ×, 1 × and 2 × of transparency, time of suspending bottles was 10:00-14:00, the amount of dissolved oxygen was determined by Winkler method, then PP in the whole day was calculated according to the results. Determination of size-fractioned structure of PP: Water samples were filtered by 200 μm sieve silk, 20 μm, 2 μm and 0.2 μm filter membrance, then the raw water and fractionated water samples were placed into dark and light bottles to suspend at the surface layer in the middle of each pond. Time of suspending bottles and determination method of dissolved oxygen were as same as PP experiment. The subtraction method was used to calculate PP of different size-fractioned phytoplanktons, while hydrochemical parameters were measured by Chinese national standards. The results showed that the annual mean value of PP was (5.16 ± 3.04) gO2 m-2 d-1 in the culture ponds, which obviously presented seasonal variations. PP reached peaks in early spring, summer and early winter, respectively. The percentage that net production of community in gross production of PP was 50.2%. The annual mean values of P/R value and daily P/B ratio were (2.20 ± 1.25) and (0.39 ± 0.35). According to the nutrient types of water which was determined by the level of PP and P/R value, the experimental ponds were eutrophic water. PP decreased with the increase of water depths. The water layer of highest production was approximately at the depth of 0.5 times of transparency. PP above 0.5 times of transparency (about 50 cm) accounted for 56.3% in total production of water column. The percentages of productions of different size-fractioned phytoplanktons in total production presented obvious seasonal variations. The contribution of micro-phytoplankton (20-200 μm) to PP was the largest (43.5%) except in summer. In summer, the largest part to PP was contributed by nano-phytoplankton (2-20 μm) (35.3%). The percentages of PP of different size-fractioned phytoplanktons in total prodution that were ordered as: micro- (40.1%) > nano- (28.2%) > meso-macro (16.1%) > pico- (15.7%). Regression analysis showed that PP in the experimental ponds with water temperature, NH4+-N, NO2--N were of significant correlation (P < 0.05), respectively. The results indicated that the seasonal variation of PP was obvious, which vertical distribution was not uniform, micro-phytoplankton was the main producer in a culture pond of A. japonicus. 参考文献 相似文献 引证文献

Seasonal variation of primary productivity in the East China Sea: A numerical study based on coupled physical-biogeochemical model

The seasonal variation of phytoplankton growth in the East China Sea (ECS) is simulated with a three-dimensional coupled physical-biogeochemical model, which includes discharges from Changjiang (Yangtze River). The purpose is to determine the main control on the seasonality of primary productivity in the ECS shelf, which nurtures rich biological resources. The model has a horizontal resolution of 1/6° in the domain from 23°N to 41°N and from 116°E to 134°E, excluding the Japan/East Sea, and 33 layers in the vertical. The nitrogen-based biogeochemical model has four compartments: dissolved inorganic nitrogen (DIN), phytoplankton, zooplankton and detritus. The chlorophyll to phytoplankton ratio depends on light and DIN availability. The model is driven by monthly climatological winds with the sea-surface temperature, salinity and DIN relaxed towards the climatological mean values. It successfully reproduces the observed seasonal variation of primary productivity over the ECS shelf with a strong peak in later spring and summer. The modeled annual mean primary production (PP) over the entire ECS shelf is 441 mg C m −2 d −1, which falls within the reported range of 390–529 mg C m −2 d −1. It also reproduces the marked seaward gradient of DIN that decreases away from the Changjiang plume. Strong dependency on the amount of photosynthetically active radiation (PAR) is demonstrated for primary production. For 1% change in PAR 0.7% change in PP is effected. Numerical experiments show that the strong summer peak of DIN load from Changjiang cannot generate the seasonality of PP without the seasonal cycle of PAR. On the other hand, the model can still produces the seasonal pattern with Changjiang nutrient load set to zero, indicating light availability as the major control. Yet the Changjiang DIN load induces a PP increase of 77 mg C m −2 d −1, which represents 13–20% of the observation based estimates of PP. It is noted that the increase in nitrogen uptake associated with PP is 2.7 times the DIN provided by the Changjiang discharge, implying efficient recycling of the riverine nutrients in the shelf water. The model needs improvement on the sluggish dispersion of the Changjiang plume and insufficient vertical mixing. It also needs a more complicated biogeochemical model with more size classes of organisms, multiple-nutrient schemes and additional geochemical processes.

Satellite-measured seasonal variations in primary production in the scallop-farming region of the Okhotsk Sea

Abstract Mustapha, M. A., Sei-Ichi, S., and Lihan, T. 2009. Satellite-measured seasonal variations in primary production in the scallop-farming region of the Okhotsk Sea. – ICES Journal of Marine Science, 66: 1557–1569. Seasonal variation in primary production after a retreat of the sea ice in the scallop-farming region along the Hokkaido coast of the Okhotsk Sea (1998–2004) was determined using satellite images. Annual variability in primary production was caused by variability in the physical processes associated with retreat of the sea ice, advection of the Sōya Warm Current (SWC), and intrusion of the East Sakhalin Current (ESC). Variability in primary production resulted in variability in the Chl a concentration, which was also demonstrated with an empirical orthogonal function (EOF) analysis. Enhancement of Chl a concentration in the frontal area in late spring was demonstrated by the second EOF mode of Chl a concentration (14.2% of variance), in parallel with the generation of a well-developed frontal area resulting from the advection of warm waters of the SWC along the coast in late spring, as indicated by the second EOF mode of sea surface temperature (SST; 1.8% of variance). Elevated Chl a concentration and the presence of cold water of the ESC in late autumn were also highlighted by the third EOF mode of Chl a concentration (9.0% of variance) and SST (1.5% of variance). Prolonged high primary production within the scallop-farming region after spring is supported by the development of a frontal area in summer and strengthening of the ESC in autumn.

Seasonal variation in primary production of a large high altitude tropical lake (Lake Tana, Ethiopia): effects of nutrient availability and water transparency

Primary production rates, chlorophyll and phytoplankton biovolume were measured monthly from April 2003 to November 2004 in Lake Tana, a large tropical lake in the highlands of Ethiopia. The lake is characterised by low nutrient concentrations, and a low water transparency due to high silt load of the inflowing rivers during the rainy seasons (May–November) and daily resuspension of sediments in the inshore zone. The mean chlorophyll-a concentrations varied seasonally and ranged from 2.6 mg m−3 to 8.5 mg m−3 (mean: 4.5 mg m−3) in the offshore zone. Primary production was measured using the light–dark bottles technique. We incubated only at three depths, i.e. 0.6, 1.2 and 1.8 m. Therefore, we may have missed a substantial part of the depth production profile and probably also frequently missed Pmax. Gross primary production in the openwater averaged 2.43 g O2 m−2 d−1 and ranged between 0.03 g O2 m−2 d−1 and 10.2 g O2 m−2 d−1; production was significantly higher in the inshore zone. The highest production rates were observed in the post-rainy season (Oct–Nov), which coincided with a bloom of Microcystis and higher chlorophyll levels. This seasonal high production is probably caused by a relatively high nutrient availability in combination with favourable light conditions. The gross primary production rates of L. Tana are among the lowest compared with other tropical lakes. This will be partly the result of our underestimation of gross primary production by often missing Pmax. Another cause is the oligotrophic nature of the lake in combination with its relatively low water transparency. The gross primary production per unit chlorophyll in the openwater zone was in the same range as in 30 other tropical lakes and reservoirs. The higher primary production in the inshore zone is probably the result of the daily water column mixing (Zmix ≥ Zt) in this area, enhancing nutrient recycling. A large proportion of the annual primary production is realised in one of the four seasons only. This productive post-rainy season is relatively short (2 months) and therefore efficiency of transfer of matter between the first and second trophic level of the Lake ecosystem will be poor.

Primary production of Utricularia foliosa L., Egeria densa Planchon and Cabomba furcata Schult &amp; Schult.f from rivers of the coastal plain of the State of São Paulo, Brazil

Seasonal variation in gross primary production (GPP) of Utricularia foliosa Linnaeus, Egeria densa Planchon and Cabomba furcata Schult & Schult.f. in rivers of the coastal plain of the state of Sao Paulo, Brazil was examined in relation to water physico-chemistry. These three species do not affect the multiple uses of the streams and are present throughout the year. The most productive was U. foliosa (maximum production 24.7 mgO2 g−1 DW h−1), while C. furcata had an intermediate GPP (maximum production 17.5 mgO2 g−1 DW h−1) and E. densa was lowest at 5.6 mgO2 g−1 DW h−1. Despite the low amplitude of seasonal variation in this south tropical area, the three species showed seasonal variation in the primary production: GPP was positively correlated with photosynthetic active radiation for U. foliosa and E. densa, and there was a negative correlation for C. furcata. For U. foliosa, GPP was positively correlated with temperature and dissolved inorganic carbon and the GPP of C. furcata was positively correlated with dissolved inorganic carbon.

Seasonal variation of average phytoplankton concentration in the Kattegat—a periodical point model

Seasonal variations in primary production, phytoplankton biomass, chlorophyll-a, dissolved inorganic phosphorus and nitrogen concentrations in the upper 10 m of the Kattegat were analysed by means of monitoring data from 1993–1997. Spatial optimal analysis, based on a stochastic model, was used to reconstruct weekly constituent fields onto a spatial grid. The reconstructed fields were spatially integrated, resulting in a relatively smooth seasonal variability of the average variables. A simple dynamical model, set up as a periodical boundary problem, is suggested for the average phytoplankton concentration, dissolved inorganic nitrogen and entrainment depth as state variables. The model is forced by the solar radiation, nitrogen load from the land sources and atmosphere as well as by nitrogen supply from the lower nutrient-rich layer. The latter process is modelled proportional to the water entrainment into the upper euphotic layer and is driven by atmospheric forcing, river runoff and the Baltic water inflow. Four model coefficient values were fitted by minimising the root mean square difference between the integrated monitoring data and the model output. The suggested diagnostic model reflects the main features in seasonal variability of phytoplankton and nitrogen concentrations by average values, including the magnitude and timing of such dynamic events as the spring and late summer phytoplankton blooms. The importance of different forcing factors is quantified and estimates of unobserved components such as new primary production can be computed.

Time series of seasonal variation of primary productivity at station KNOT (44°N, 155°E) in the sub-arctic western North Pacific

Abstract Phytoplankton biomass and primary productivity were measured as a part of the station KNOT (44°N, 155°E) time-series observation program in the western North Pacific, which began in June 1998 and continued on a nearly monthly basis until February 2000. Primary productivity was measured by the 13C uptake method using a clean sampling technique. The surface temperature changed from 2°C to 15°C, and the minimum and maximum temperatures were in February and August, respectively. The minimum and maximum concentrations of surface-layer nutrients were 2.2 and 19.6 μM for nitrate+nitrite, 0.32 and 1.64 μM for phosphate, and 3.3 and 33.3 μM for silicate. The averaged depth of euphotic zone was about 50 m, which did not show clear seasonality. Integrated chlorophyll a in the euphotic zone ranged between 20 and 40 mg Chl a m−2, except for the high values (51–64 mg Chl a m−2) in early June and middle October 1998 and May 1999, and the low value (17 mg Chl a m−2) in late June 1998. The integrated primary productivities in the upper part of the euphotic zone for spring (May), summer (June–August), autumn (October–November), and winter (December–February) were 517–535 (av. 526), 153–304 (av. 227), 101–307 (av. 173), and 25–121 (av. 48) mg C m−2 d−1, respectively. The annual productivity was estimated to be 90 g C m−2 yr−1. The results showed that primary productivity had a distinct seasonal variation, with a 10-fold range during winter–spring, which is far larger than that at Ocean Station Papa (OSP) in the eastern North Pacific. However, the annual productivity at station KNOT was lower than the at OSP. It was found that the light utilization index was constant during all seasons, and the annual average (±1 SD) was 0.30±0.10 g C (g Chl a)−1 m2 (mol quanta)−1.

Seasonal variation in primary production of microphytobenthos at the Isshiki intertidal flat in Mikawa Bay

Seasonal variations in photosynthetic rates by microphytobenthos and phytoplankton at the Isshiki tidal flat in Mikawa Bay were measured with a 14C combustion method. In addition, diurnal variations in the photosynthetic rate and photosynthesis versus irradiance (P-I) curves were obtained through in situ incubation. The photosynthetic rate of microphytobenthos (annual average, 13.9 ± 6.4 mg C m−2 h−1) did not show a remarkable change, and they maintained a higher production rate than phytoplankton (annual average 9.0 ± 5.1 mg C m−2 h−1) throughout the year. The P-I curves from in situ experiments showed that the photosynthetic activity of microphytobenthos at the laboratory irradiance (250 μE m−2 s−1) was 56% of that at the maximum irradiance (1200 μE m−2 s−1) in situ. In the in situ experiments, the chlorophyll a concentration, photosynthetic rate, and activity of microphytobenthos varied greatly throughout the day, influenced by tidal submersion/emersion and daylight. From an analysis of these results, it is considered that microphytobenthos contributed greatly to primary production in this ecosystem throughout the year by adapting suitably to intertidal environments.

Seasonal variation of primary productivity and skeletal delta13C and delta18O in the zooxanthellate scleractinian coral Acropora formosa

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 157:109-117 (1997) - doi:10.3354/meps157109 Seasonal variation of primary productivity and skeletal delta13C and delta18O in the zooxanthellate scleractinian coral Acropora formosa A. Juillet-Leclerc1,*, J.-P. Gattuso2,3, L. F. Montaggioni4, M. Pichon3,5 1Centre des Faibles Radioactivités, Laboratoire mixte CNRS-CEA, F-91180 Gif-sur-Yvette Cedex, France 2Observatoire Océanologique Européen, Centre Scientifique de Monaco, Avenue Saint-Martin, MC-98000 Monaco 3Australian Institute of Marine Science, PMB no. 3, Townsville MC, Queensland 4810, Australia 4UPRESA-CNRS 6019, Centre de Sédimentologie/Paléontologie, Université de Provence, F-13331 Marseille Cedex 3, France 5Laboratoire de Biologie Marine, EPHE, URA-CNRS 1453, Université de Perpignan, F-66860 Perpignan Cedex, France *E-mail: anne.juillet-leclerc@cfr.cnrs-gif.fr Carbon and oxygen isotopic ratios, measured along the growth axis of branches from colonies of the scleractinian coral Acropora formosa collected at 2 and 12 m depth at Yonge Reef (Northern Great Barrier Reef, Australia), were compared to metabolic rates. Measurements of primary production, respiration, temperature and irradiance were carried out in situ twice, in winter and in summer, and skeletal isotopic analyses were performed at 2 reference points corresponding to metabolic measurements. There was no evidence of any relationship between oxygen isotopic ratio and productivity. Skeletal delta13C values and the rates of productivity showed a statistically significant positive relationship as predicted by the model proposed by Goreau (1977a: Proc 3rd Int Coral Reefs Congr 1:395-401); delta13C increased as a function of increasing productivity. The scattering of delta13C observed particularly during summer demonstrates that the relationship between delta13C and primary productivity is not very tight and that other internal and external parameters probably operate to explain the delta13C variability. Acropora formosa · Productivity · Skeletal delta13C and delta18O Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 157. Publication date: October 16, 1997 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1997 Inter-Research.

Multiple Factors Limit Seasonal Variation in Periphyton in a Forest Stream

This study was conducted to characterize periphyton biomass, productivity, and algal species composition, and to examine how these parameters changed seasonally over the course of two years in Walker Branch, a temperate forest stream. Seasonal variations in several factors potentially controlling periphyton (irradiance, streamwater nutrient concentrations, temperature, and the incidence of severe storms) were large. However, there was no consistent seasonal variation in herbivore (snail) density, which was high (> 1000 animals/m 2 ). Regression analysis was conducted to determine the influence of potential controlling factors on periphyton biomass and productivity. Seasonal changes in periphyton biomass were small and only weakly related to irradiance (-), snail density (-), and temperature (+). Biomass was lowest in early spring and highest in summer in 1989; but during the following year, biomass was similar year-round. Seasonal variation in primary productivity was also relatively small, but w...