Dependence of settlement rate on suitable substrate area

Several recent field studies have found disproportionately high barnacle settlement rates (expressed on a per-area basis) in situations where the amount of suitable substrate is reduced, either due to occupation by other individuals or to physical processes. We call this phenomenon the intensification effect; it is not included in many models of benthic populations, which assume that the per-area settlement rate is a constant, or in field larval-collector studies, where number of larvae caught is assumed to be a function only of larval supply. In this paper we derive a simple Markov chain model that generates the intensification effect. It describes the fate of a settling larva, which may be washed out of the system or may attempt to settle in suitable or unsuitable substrate. If it lands on unsuitable substrate, it returns to the water column to try again. At low values of the washout rate, the per-area settlement rate decreases with increasing substrate area. At high values of the washout rate, per-area settlement rate is constant. We conducted a set of laboratory experiments in March through April 1995 with barnacle larvae (Semibalanus balanoides Linnaeus) to illustrate the predictions of the model. Substrate area was manipulated by varying the number of settling panels available, and the larval loss rate was adjusted by manipulating the residence time of larvae in the experimental units (1.5 h or 12 h). As predicted by the model, in the 12-h treatment settlement per area decreased nonlinearly as the amount of substrate increased, whereas in the 1.5-h treatment no differences were found. These results explain and predict the intensification effect, and suggest that variability in the proportion of suitable substrate may be an important factor in determining variability in settlement rate. Received: 27 May 1997 / Accepted: 10 June 1997     

The theoretical basis for estimating phytoplankton production and specific growth rate from chlorophyll, light and temperature data

Phytoplankton maximum specific growth rate, μ_max, and maximum photosynthetic quantum yield, Φ_max, can be related mathematically via the photosynthetic light curve, P(I). A model is presented in which maximum quantum yield defines the initial slope of the light curve and is assumed to be a known constant, while maximum specific growth rate defines the light-saturated region of the curve and is assumed to be a known function of temperature. The effect of introducing μ_max(T) into P(I, Φ_max) is to replace the unknown, temperature-dependent light saturation parameter with a term involving the ratio μ_max/Φ_max. The advantage of writing P(I) in terms of both μ_max and Φ_max is that those parameters are particularly well documented in the literature. Consequently, estimates of nutrient-unlimited phytoplankton growth and production rates can be based solely on the constants μ_max, Φ_max and k_c (light absorption per unit of chlorophyll) and the free variables light, temperature and chlorophyll concentration. Rate estimates appear to be accurate to within a factor of two for an extremely wide range of conditions.One particularly significant result of introducing μ_max into P(I, Φ_max) is that the carbon : chlorophyll ration, θ, appears explicitly. It is possible to derive an expression for optimum θ based on the assumption that adaptive changes in carbon/chlorophyll occur so as to maximize the specific growth rate for given conditions of light and temperature. Laboratory and field data are compiled from the literature to test the formulae presented here.     

Primary production and phytoplankton community structure during a winter shelf-scale phytoplankton bloom off Western Australia

Regions of high primary production along the oligotrophic west coast of Australia between 34 and 22°S in May–June 2007 (midway through the annual phytoplankton bloom) were found around mesoscale features of the Leeuwin Current. At 31°S, an anticyclonic eddy-forming meander of the Leeuwin Current had a mixed layer depth of >160 m, a depth-integrated chlorophyll a (Chl a)-normalised primary production of 24 mg C mg Chl a ^?1 day^?1 compared to the surrounding values of <18 mg C mg Chl a ^?1 day^?1. In the north between 27 and 24°S, there were several stations in >1,000 m of water with a shallow (<100 m) and relatively thin layer of high nitrate below the mixed layer but within the euphotic zone. These stations had high primary production at depths of ~100 m (up to 7.5 mg C m^?3 day^?1) with very high rates of production per unit Chl a (up to 150 mg C mg Chl a ^?1 day^?1). At 27–24°S, the majority of the phytoplankton community was the ubiquitous tropical picoplankters, Synechococcus and Prochlorococcus. There was a decline in the dominance of the picoplankters and a shift towards a more diverse community with more diatoms, chlorophytes, prasinophytes and cryptophytes at stations with elevated production. Photosynthetic dinoflagellates were negligible, but heterotrophic dinoflagellate taxa were common. Haptophytes and pelagophytes were also common, but seemed to contribute little to the geographical variation in primary production. The mesoscale features in the Leeuwin Current may have enhanced horizontal exchange and vertical mixing, which introduced nitrate into the euphotic zone, increasing primary production and causing a shift in phytoplankton community composition in association with the annual winter bloom.     

The influence of salinity on the rate of photosynthesis and abundance of some tropical phytoplankton

Several species of phytoplankton were grown in unialgal, but not bacteria-free, cultures. These clones when exposed to varying salinities, from 5 to 35, showed a marked increase in their rates of photosynthesis at low salinities. The optimum requirement of salinity, however, varied in different species. Observations on the relative abundance of phytoplankton in an estuary, where the salinity changes were fairly large, confirmed that, within limits, waters with low salinities support a greater abundance of phytoplankton in nature. The wide adaptability of phytoplankton to changes in salinity corresponds to the conditions brought about by the monsoon system along the southwest coast of India, where large dilutions are associated with the enrichment of water with nutrients.     

Circadian variations in photosynthetic assimilation and estimation of daily phytoplankton production

In August 1984, hourly measurements of photosynthetic characteristics were carried out during 96 h, at 5 and 10 m, on a natural population of phytoplankton in the St Lawrence Estuary. Synchronous circadian variations of similar amplitude (max./min.: 2 to 3) were observed at the two depths in both the photosynthetic capacity (P _m ^B ) and the photosynthetic efficiency (^B). Maximum values occurred at around noontime and minima during the night. Estimates of daily specific productivity were computed with and without the observed circadian variability. Large differences (15 to 70%) were evidenced between estimates.Contribution to the programs of GIROQ (Groupe interuniversitaire de recherches océanographiques du Québec) and of the Maurice Lamontagne Institute (Department of Fisheries and Oceans)     

Russell's definite description analysis of production and limitation of phytoplankton species

The majority of phytoplankton species observed in the southwestern Atlantic Ocean produce new cells to equal cells lost, if any, to grazing and sinking. At the same time these species must limit new cells to numbers equalling any lost, since their abundance remains about the same in both deep and shallow areas. Of each of these species one may assert: the producer is a limiter (1). One species, coccolithus huxleyi, produces cells to offset any lost in deep water but does not limit, as it drifts into shallow water, new cells to equal the number lost in deep water, since it is more abundant in shallow than in deep water. For C. huxleyi it is true that the producer is not a limiter (2). However, once in the shallows, C. huxleyi is in a steady state, so that nutrient concentration both produces and limits new cells to equal any lost. Thus, (2) converts to (1) by having nutrient concentration the producer and the limiter. “The producer is a limiter” is a covering statement. Asserting it covers all observable species; denying it covers species not observed, those rare species which can only be found by more exhaustive sampling.     

Examination of hydroxamate-siderophore production by neritic eukaryotic marine phytoplankton

Species of neritic eukaryotic marine phytoplankton were investigated during 1982 for hydroxamate-type siderophore production under iron-sufficient and iron-deficient culture conditions. Three of the 5 Prorocentrum species examined produced siderophores. Prorocentrin, the extracellular hydroxamate-type siderophore isolated from P. minimum, was also produced by P. mariae-lebouriae and P. gracile. P. maximum and P. micans grew poorly in iron-deficient medium and did not produce intracellular or extracellular hydroxamate-type siderophores. Thalassiosira pseudonana and Dunaliella tertiolecta produced extracellular siderophores under iron-deficient conditions, but siderophore production was not detected in the other two species, Skeletonema costatum and Olisthodiscus luteus. Each species which produced extracellular Csaky-positive hydroxamate showed a similar pattern of production. Under iron-sufficient conditions there was no measurable siderophore found either intracellularly or extracellularly. Under iron-deficient culture conditions hydroxamate-type siderophore was produced 1 to 2 d after the cessation of growth in the stationary phase. Production was over a short period of time (1 to 2 d) and the siderophore did not remain in the medium. The rate of siderophore disappearance from the medium was similar to the rate of production. Each species which produced siderophores showed an increase in in vivo fluorescence coincidental with the disappearance of the extracellular siderophore from the culture medium. There was no corresponding increase in in vivo fluorescence in iron-sufficient cultures. It is suggested that in vivo fluorescence may be used as a screening procedure for determining hydroxamate-type siderophore production in eukaryotic phytoplankton. An hypothesis on the iron uptake mechanism is proposed.     

Fractionated phytoplankton primary production,exudate release and bacterial production in a Baltic eutrophication gradient

The distribution of phytoplankton primary production into four size fractions (>10 m, 10-3 m, 3-0.2 m and <0.2 m), the utilization of algal exudates by bacteria and the bacterial production were studied in a eutrophication gradient in the northern Baltic proper. The polluted area exhibits substantially increased nutrient, especially nitrogen, levels while only minor differences occur in salinity and temperature regimes. Total primary production was 160 g C · m^-2 · yr^-1 at the control station and about 275 g C · m^-2 · yr^-1 at the eutrophicated stations. The estimated total exudate release was 16% of the totally fixed ¹⁴CO₂ in the control area and 12% in the eutrophicated area (including the estimated bacterial uptake of exudates). The difference in¹⁴CO₂ uptake rates between incubation of previously filtered water (<3, <2, <1 m) and unfiltered water was used to estimate bacterial uptake of phytoplankton exudates which were found to contribute about half of the estimated bacterial carbon requirement in both areas. Bacterial production was estimated by the frequency of dividing cells (FDC) method as being 38 g C · m^-2 · yr^-1 at the control station and 50 g C · m^-2 · yr^-1 at the eutrophicated stations. To estimate the mean in situ bacterial cell volume a correlation between FDC and cell volume was used. The increased annual primary production in the eutrophicated area was due mainly to higher production during spring and autumn, largely by phytoplankton cells (mainly diatoms) retained by a 10 m filter. Primary production duringsummer was similarin the two areas, as was the distribution on different size fractions. This could possibly explain the similar bacterial production in the trophic layers at all stations since the bulk of bacterial production occurs during summer. It was demonstrated that selective filtration does not quantitatively separate photoautotrophs and bacteria. A substantial fraction of the primary production occurs in the size fraction <3 m. The primary production encountered in the 3-0.2 m fraction was due to abundant picoplankton (0.5 to 8 · 10⁷ ind · l^-1), easily passing a 3 m filter. The picoplankton was estimated to constitute up to 25% of the total phytoplankton biomass in the control area and up to 10% in the eutrophicated area.     

Lectin-induced enhancement of superoxide anion production by red tide phytoplankton

Chattonella marina, a raphidophycean flagellate, is a highly toxic red tide phytoplankton which causes severe damage to fish farming. Recent studies demonstrated that Chattonella spp. continuously release superoxide anions (O₂ ⁻) while they are living. Heterosigma akashiwo, another raphidophycean flagellate, also produces O₂ ⁻. In the present study, we found that lectins such as concanavalin A (Con A), wheat germ agglutinin (WGA), and castor bean hemagglutinin (CBH) stimulated  C. marina and H. akashiwo to generate enhanced amounts of O₂ ⁻ in a concentration-dependent manner. The lectin-specific sugars potently inhibited the lectin-induced increase of O₂ ⁻ production, suggesting that the effects of lectins are mediated mainly through the interaction of these lectins with carbohydrate moiety present on the flagellate cell surface. In contrast to the potent ability of native Con A (tetravalent), succinylated Con A (divalent) showed only a slight stimulative effect on these flagellates. O₂ ⁻ production was totally inhibited by treatment with proteinase K for 30 min, without affecting the viabilities of flagellates. These results suggest that cell-surface redox enzymes may be involved in O₂ ⁻ production, and such enzymes are responsible for the lectin-stimulation. Received: 21 August 1997 / Accepted: 8 January 1998     

Primary production as influenced by diel periodicity of phytoplankton photosynthesis

Diel periodicity in parameters of photosynthesis-irradiance (P-I) curves was incorporated into calculations of integral daily phytoplankton production for the Santa Barbara Channel off southern California (USA). Model equations of the relationship between photosynthesis and light were used in combination with observed slope () and asymptote (P _max) values presented in the preceding paper. Primary production was always 19 to 39% less than comparable estimates obtained with the assumption of constant maximum daily and P _max values. Regardless of which P-I formulation was used of 6 tested, observed production (using a temporal series of simulated in situ incubations) ranged from 13% less to 25% more than estimates from constant midday and P _max values. The amplitude and timing of diel oscillations differed somewhat among 3 field stations. Maximum to minimum ratios ranged from approximately 3 to 5 for , and 4 to 6 for P _max. The differences in amplitude and timing of oscillations in P-I curves both contributed to errors in calculating phytoplankton production. Thus, photosynthetic periodicity in the upwelling area of the Santa Barbara Channel influences phytoplankton production. There were oscillations in both and P _max, and the time-dependence of these parameters should be considered to improve the accuracy of predictive models of primary productivity.     

Carbon assimilation and lipid production in phytoplankton in northern Norwegian fjords

Carbon assimilation and lipid production were studied in phytoplankton in Balsfjorden and Ullsfjorden, northern Norway, during the exponential growth phase of the spring bloom in 1983 (6–7 April). In Balsfjorden, phytoplankton biomass was constant with depth and equivalent to 1.5 g chlorophyll a 1^-1. Phytoplankton biomass in Ullsfjorden varied with depth, with a maximum of ca. 7 g chlorophyll a 1^-1 occurring at 5 to 10 m. Particulate carbon-14 assimilation was about 18 mg C per m^-2 h^-1 in Balsfjorden and about 39 mg C per m^-2 h^-1 in Ullsfjorden over the depth range 4 to 8 m. In Balsfjorden, the percentage of total fixed carbon recovered as total lipid was 14.7 and 20.4% at 4 and 8 m depth, respectively. In Ullsfjorden, the corresponding values were 8.8 and 28.1% at 4 and 8 m, respectively. The percentages of total fixed carbon present as fatty acids were 1.1 and 1.6% at 4 and 8 m, respectively, in Balsfjorden, and 0.8 and 6.4% at 4 and 8 m in Ullsfjorden. The majority of the radioactivity in lipid at both locations and at both depths was present as polar lipid, with small percentages present in triacylglycerols and very small percentages present in free fatty acids. On average, about 18% of the total carbon-14 incorporated into phytoplankton over a 6 to 7 h mid-day period was recovered as total lipid and its percentage tended to increase with depth. The relatively low percentage of incorporated carbon-14 present as fatty acids in total lipid implies that most of the radioactivity is present in glyceryl and/or glucosyl moieties and that measurement of total radioactivity in total lipid does not necessarily give an accurate estimation of lipogenesis in phytoplankton. Fatty acid analyses of total phytoplankton in Balsfjorden and Ullsfjorden in 1983 and of a surface slick at the end of a bloom of Phaeocystis pouchetii in Balsfjorden in May 1980 showed an abundance (more than 40% of the total) of (n-3) polyunsaturates in all cases. C-18 polyunsaturates, especially 18:4 and 18:5, were very abundant (about 30% of the total) in the P. pouchetii surface slick in Balsfjorden in 1980. Both P. pouchetii biomass and C-18 polyunsaturates were more abundant in Ullsfjorden than in Balsfjorden (1983). Lipids from the P. pouchetii surface slick were deficient in C-16 polyunsaturates and relatively deficient in C-20 polyunsaturates, but both these classes of fatty acids were abundant in Balsfjorden and Ullsfjorden in 1983. The phytoplankton in both locations in 1983 was dominated by P. pouchetii and diatoms; Chaetoceros socialis was especially abundant in Balsfjorden. The results are discussed in terms of the fatty acids present in herbivorous zooplankton in northern Norwegian fjords.     

Demands of the herbivore community on phytoplankton production in the Celtic Sea in August

The apodous detritivore holothurian Leptosynapta galliennei (Herapath, 1865) was collected from the intertidal zone (Brittany, France) in spring 1983, and the effect of short-term starvation on the biochemical composition of different body parts was studied. Variations in the levels of the main organic components of the somatic tissues did not correspond to the observed ponderal growth of the gonad in either males or females. Part of the increase in the energetic value of the testis was due to carbohydrates. Accumulation of carbohydrates, proteins, and especially lipids occurred in the ovary. Glycogen, often considered as the most readily mobilized energy source, varied little in concentration or in quantity in any body part. Lipids were not mobilized. No organ of this thin-skinned holothurian functions as a site of rapidly usable food reserves. The organic nitrogen and carbon necessary to compensate for metabolic loss and to permit gonadal growth during shortterm starvation may be provided by dissolved organic matter. An efficient transintegumentary uptake of dissolved organic matter, perhaps mediated by associated subcuticular bacteria, and/or intestinal uptake are hypothesized.     

Warming induces shifts in microzooplankton phenology and reduces time-lags between phytoplankton and protozoan production

Indoor mesocosm experiments were conducted to test for potential climate change effects on the spring succession of Baltic Sea plankton. Two different temperature (Δ0?°C and Δ6?°C) and three light scenarios (62, 57 and 49?% of the natural surface light intensity on sunny days), mimicking increasing cloudiness as predicted for warmer winters in the Baltic Sea region, were simulated. By combining experimental and modeling approaches, we were able to test for a potential dietary mismatch between phytoplankton and zooplankton. Two general predator–prey models, one representing the community as a tri-trophic food chain and one as a 5-guild food web were applied to test for the consequences of different temperature sensitivities of heterotrophic components of the plankton. During the experiments, we observed reduced time-lags between the peaks of phytoplankton and protozoan biomass in response to warming. Microzooplankton peak biomass was reached by 2.5 day °C^?1 earlier and occurred almost synchronously with biomass peaks of phytoplankton in the warm mesocosms (Δ6?°C). The peak magnitudes of microzooplankton biomass remained unaffected by temperature, and growth rates of microzooplankton were higher at Δ6?°C (μ_?0?°C?=?0.12 day^?1 and μ_?6?°C?=?0.25 day^?1). Furthermore, warming induced a shift in microzooplankton phenology leading to a faster species turnover and a shorter window of microzooplankton occurrence. Moderate differences in the light levels had no significant effect on the time-lags between autotrophic and heterotrophic biomass and on the timing, biomass maxima and growth rate of microzooplankton biomass. Both models predicted reduced time-lags between the biomass peaks of phytoplankton and its predators (both microzooplankton and copepods) with warming. The reduction of time-lags increased with increasing Q₁₀ values of copepods and protozoans in the tritrophic food chain. Indirect trophic effects modified this pattern in the 5-guild food web. Our study shows that instead of a mismatch, warming might lead to a stronger match between protist grazers and their prey altering in turn the transfer of matter and energy toward higher trophic levels.     

黄海春季表层叶绿素和初级生产力及其粒径结构研究

根据2006年4月对黄海浮游植物分级叶绿素及初级生产力的调查,研究了黄海叶绿素及初级生产力的水平分布及粒级结构特征,并分析了其主要影响因素。黄海海域调查站位表层叶绿素a质量浓度变化范围为0.20～4.94μg·L-1,平均值为0.96μg·L-1。叶绿素最大值出现在临近长江口的站位。叶绿素分级结果表明黄海春季以粒径〉5μm的浮游植物占优势。黄海表层初级生产力的变化范围为2.03～15.64mg·m-3·h-1,平均值为6.08mg·m-3·h-1。其中南黄海海域初级生产力平均为6.58mg·m-3·h-1,北黄海海域初级生产力平均为4.92mg·m-3·h-1。高值区分布在南黄海中部。受水体透明度的影响,低值区出现在临近长江口的站位。断面站位分析表明浮游植物初级生产力由北向南逐步升高,温度随纬度的变化是南北海域初级生产力水平差异的主要原因。由于粒径较小（〈5μm）的浮游植物单位叶绿素具有较高的碳固定能力,调查期间整个海区初级生产力以粒径〈5μm的浮游植物贡献为主。     

Nutrient cycling studies in Carmarthen Bay: phytoplankton production,nitrogen assimilation and regeneration

The results from a series of five cruises (August 1979–January 1981) to examine rates of primary production, nitrogen assimilation and regeneration in Carmarthen Bay, S. Wales, are presented. Chlorophyll, primary production and regeneration were distributed irregularly throughout the bay, with the highest concentrations and rates being found around the shallow periphery. Nitrate was the dominant form of nitrogen assimilated by the phytoplankton, apart from periods of high biomass during the summer when ammonium assumed a more important role. The rates of ammonium regeneration from microheterotrophs were greater than the ammonium demand over much of the year, indicating that the bay was a net exporter of ammonium and was a physically dominated open system. During the summer, the rates of ammonium regeneration and assimilation were similar, indicating efficient recycling of nutrients.     

Availability of copper from phytoplankton and water for the bivalveMacoma balthica. II. Uptake and elimination from64Cu-labelled diatoms and water

The amount of copper taken up via algae and water byMacoma balthica from the Oosterschelde sea arm, S.W. Netherlands, was established using the radioisotope⁶⁴Cu. As far as we know, this isotope has never been used before in marine flod chain studies. As a model food source the marine diatomPhaeodactylum tricornutum was allowed to accumulate⁶⁴Cu for 1 d. These labelled algae were fed to the clams in the presence of the complexing agent EDTA (0.27mM). EDTA was added to prevent uptake of dissolved⁶⁴Cu that could be leaking from the labelled diatoms. In control experiments, unlabelled diatoms were fed toM. balthica in the presence of dissolved⁶⁴Cu (with and without EDTA) in order to assure a similar filtration activity. In repeated experiments with varying particulate/dissolved copper ratios, uptake through food always turned out to be at least as efficient as uptake from the water. It was concluded that Cu, associated with food, is well available for uptake byM. balthica.     

Nutrient-limited toxin production and the dynamics of two phytoplankton in culture media: A mathematical model

In this paper we have proposed and analyzed a simple mathematical model consisting of four variables, viz., nutrient concentration, toxin producing phytoplankton (TPP), non-toxic phytoplankton (NTP), and toxin concentration. Limitation in the concentration of the extracellular nutrient has been incorporated as an environmental stress condition for the plankton population, and the liberation of toxic chemicals has been described by a monotonic function of extracellular nutrient. The model is analyzed and simulated to reproduce the experimental findings of Graneli and Johansson [Graneli, E., Johansson, N., 2003. Increase in the production of allelopathic Prymnesium parvum cells grown under N- or P-deficient conditions. Harmful Algae 2, 135–145]. The robustness of the numerical experiments are tested by a formal parameter sensitivity analysis. As the first theoretical model consistent with the experiment of Graneli and Johansson (2003), our results demonstrate that, when nutrient-deficient conditions are favorable for the TPP population to release toxic chemicals, the TPP species control the bloom of other phytoplankton species which are non-toxic. Consistent with the observations made by Graneli and Johansson (2003), our model overcomes the limitation of not incorporating the effect of nutrient-limited toxic production in several other models developed on plankton dynamics.     

Stimulation of phytoplankton production in coastal waters by natural rainfall inputs: Nutritional and trophic implications

Recent evaluations of estuarine and coastal nutrient budgets implicate atmospheric deposition as a potentially significant (20 to 30%) source of biologically available nitrogen. We examined the potential growth stimulating impact of atmospheric nitrogen loading (ANL), as local rainfall, in representative shallow, nitrogen limited North Carolina mesohaline estuarine and euhaline coastal Atlantic Ocean habitats. From July 1988 to December 1989, using in situ bioassays, we examined natural phytoplankton growth responses, as¹⁴CO₂ assimilation and chlorophylla production, to rain additions over a range of dilutions mimicking actual input levels. Rainfall at naturally occurring dilutions (0.5 to 5%) stimulated both¹⁴CO₂ assimilation and chlorophylla production, in most cases in a highly significant manner. Parallel nutrient enrichments consistently pointed to nitrogen as the growth stimulating nutrient source. Generally, more acidic rainfall led to greater magnitudes of growth stimulation, especially at lower dilutions. Nutrient analyses of local rainfall from May 1988 to January 1990 indicated an inverse relationship between pH and NO ₃ ^- content. There have been growing concerns regarding increasing coastal and estuarine eutrophication, including ecologically and economically devastating phytoplankton blooms bordering urban and industrial regions of North America, Europe, Japan, and Korea. It appears timely, if not essential, to consider atmospheric nutrient loading in the formulation and implementation of nutrient management strategies aimed at mitigating coastal eutrophication.     

Developing an empirical model of phytoplankton primary production: a neural network case study

We describe the development of a neural network model for estimating primary production of phytoplankton. Data from an enriched estuary in the eastern United States, Chesapeake Bay, were used to train, validate and test the model. Two error backpropagation multilayer perceptrons were trained: a simpler one (3-5-1) and a more complex one (12-5-1). Both neural networks outperformed conventional empirical models, even though only the latter, which exploits a larger suite of predictive variables, provided truly accurate outputs. The application of this neural network model is thoroughly discussed and the results of a sensitivity analysis are also presented.     

Measurement of photosynthetic production of a marine phytoplankton population using a stable 13C isotope

The use of stable isotope of carbon, ¹³C, for the determination of the photosynthetic rate of a marine phytoplankton population was examined. Particular concern was paid to the effects of non-phytoplanktonic organic carbon and the enrichment of inorganic carbon on the estimation of the photosynthetic rate. Photosynthetic rates determined by the ¹³C method showed a remarkable agreement with those determined by the ¹⁴C method. Insitu determinations of photosynthetic rate were made in three different water types: open ocean, coastal and neritic waters, which included oligo- and mesotrophic waters, by using the ¹³C method established.