Phytoplankton Cell Volume Research Articles

Phytoplankton carbon and nitrogen biomass estimates are robust to volume measurement method and growth environment

Abstract Phytoplankton biomass is routinely estimated using relationships between cell volume and carbon (C) and nitrogen (N) content that have been defined using diverse plankton that span orders of magnitude in size. Notably, volume has traditionally been estimated with geometric approximations of cell shape using cell dimensions from planar two-dimensional (2D) images, which requires assumptions about the third, depth dimension. Given advances in image processing, we examined how cell volumes determined from three-dimensional (3D), confocal images affected established relationships between phytoplankton cell volume and C and N content. Additionally, we determined that growth conditions could result in 30–40% variation in cellular N and C. 3D phytoplankton cell volume measurements were on average 15% greater than the geometric approximations from 2D images. Volume method variation was minimal compared to both intraspecific variation in volumes (~30%) and the 50-fold variation in elemental density among species. Consequently, C:vol and N:vol relationships were unaltered by volume measurement method and growth environment. Recent advances in instrumentation, including those for at sea and autonomous applications can be used to estimate plankton biomass directly. Going forward, we recommend instrumentation that permits species identification alongside size and shape characteristics for plankton biomass estimates.

Multiannual decrement of nutrient concentrations and phytoplankton cell size in a Mediterranean reservoir

Reservoirs are primary water resources for many uses in the Mediterreanean region and need dedicated studies for understanding the complexity of their dynamics particularly vulnerable to local and global stressors. This study focused on phytoplankton variations in relation to seasonal environmental changes on a multiannual time scale (2006–2015) at a Mediterranean eutrophic reservoir (Bidighinzu Lake, Italy) belonging to the Italian, European and International Long Term Ecological Research networks. Phytoplankton cell density, volume and biomass and chlorophyllaconcentrations were analysed together with meteo-climatic, hydrological, physical and chemical variables to detect trends and correlations. The period under study was also compared with previous years to assess the presence of significant differences in the environmental and planktonic compartments. Multiannual changes were more pronounced in summer than in the other seasons during the decade under study. The most conspicuous environmental changes were a significant decrease in summer nutrient concentrations in the reservoir and a simultaneous anthropic pressure reduction in the watershed. In addition, the mixing zone and euphotic zone ratio also increased. Multiannual changes in summer phytoplankton composition consisted of an increased density of smaller Bacillariophyceae and Cyanophyceae, which replaced larger species of the same phytoplankton classes. This resulted in opposite trends of total phytoplankton cell density (increasing) and mean phytoplankton cell volume (decreasing) over the study years. The nutrient decrement was statistically the strongest environmental driver of the phytoplankton changes observed in the reservoir. However, the mixing zone and the euphotic zone ratio and water temperature also significantly affected the multiannual phytoplankton variations. Therefore, we conclude that the success of small cell-sized phytoplankton in Bidighinzu Lake was most probably due to the synergic interactions of more environmental forces related to changing anthropic pressures and climate variability. Our results highlight the importance of long-term monitoring of reservoirs in the Mediterranean basin, especially in semi-arid regions where the need and scarcity of high quality water will be further exacerbated due to the global climate change.

The role of the diatom cell form in the competition for light energy

We proposed a new parameter regulating distribution of the species – the daily average absorbed energy of PAR by a unit of phytoplankton cell volume, determined by the shape, size and concentration of pigments. We calculated this parameter for some dominant diatom species of the northeastern part of the Black Sea and normalize it by the average daily PAR for periods of dominance. We established that for species successfully compete for an ecological niche this parameter should be approximately at the same level in different seasons.

Effects of Lugol’s iodine solution and formalin on cell volume of three bloom-forming dinoflagellates

Fixatives are traditionally used in marine ecosystem research. The bias introduced by fixatives on the dimensions of plankton cells may lead to an overestimation or underestimation of the carbon biomass. To determine the impact of traditional fixatives on dinoflagellates during short- and long-term fixation, we analyzed the degree of change in three bloom-forming dinoflagellates (Prorocentrum micans, Scrippsiella trochoidea and Noctiluca scintillans) brought about by Lugol’s iodine solution (hereafter Lugol’s) and formalin. The fixation effects were species-specific. P. micans cell volume showed no significant change following long-term preservation, and S. trochoidea swelled by approximately 8.06% in Lugol’s and by 20.97% in formalin as a percentage of the live cell volume, respectively. N. scintillans shrank significantly in both fixatives. The volume change due to formalin in N. scintillans was not concentration-dependent, whereas the volume shrinkage of N. scintillans cells fixed with Lugol’s at a concentration of 2% was nearly six-fold that in cells fixed with Lugol’s at a concentration of 0.6%–0.8%. To better estimate the volume of N. scintillans fixed in formalin at a concentration of 5%, we suggest that the conversion relationship was as follows: volume of live cell=volume of intact fixed cell/0.61. Apart from size change, damage induced by fixatives on N. scintillans was obvious. Lugol’s is not a suitable fixative for N. scintillans due to high frequency of broken cells. Accurate carbon biomass estimate of N. scintillans should be performed on live samples. These findings help to improve the estimate of phytoplankton cell volume and carbon biomass in marine ecosystem.

The role of phytoplankton composition, biomass and cell volume in accumulation and transfer of endocrine disrupting compounds in the Southern Baltic Sea (The Gulf of Gdansk)

Endocrine disrupting compounds (EDCs) like bisphenol A (BPA), 4-tert-octylphenol (OP) and 4-nonylphenol (NP) are introduced to the trophic webs through among others phytoplankton. This paper describes BPA, OP and NP concentrations in phytoplankton in the Gulf of Gdansk (Southern Baltic Sea) in the years 2011–2012. The assays of BPA, OP and NP in samples were performed using HPLC with fluorescence detection. The concentrations of BPA, the most commonly used of the three compounds, were over ten times higher than OP and NP concentrations. The concentrations of the studied EDCs in phytoplankton from the Gulf of Gdansk depended on anthropogenic factors and on phytoplankton properties (species composition, biomass, volume). An increase in phytoplankton biomass did not always result in an increase of BPA, OP and NP concentrations. However, the load of the studied EDCs accumulated in phytoplankton biomass increase with a rise of biomass. An increase in BPA, OP and NP concentrations was effected by biomass growth and the proportions ofciliates, dinoflagellates, diatoms and green algae. A strong positive correlation between OP and NP concentrations and negative correlation between BPA concentrations and biomass of organisms with cells measuring <1000 μm3 in volume results from the differing properties of these compounds.

Size-dependence of volatile and semi-volatile organic carbon content in phytoplankton cells

The content of volatile and semivolatile organic compounds (VOC and SOC), measured as exchangeable dissolved organic carbon (EDOC), was quantified in 9 phytoplanktonic species that spanned 4 orders of magnitude in cell volume, by disrupting the cells and quantifying the gaseous organic carbon released. EDOC content varied 4 orders of magnitude, from 0.0015 to 14.12 pg C cell-1 in the species studied and increased linearly with increasing phytoplankton cell volume following the equation EDOC (pg C cell-1) = -2.35 x cellular volume (CV, µm3 cell-1) 0.90 (± 0.3), with a slope (0.90) not different from 1 indicating a constant increase in volatile carbon as the cell size of phytoplankton increased. The percentage of EDOC relative to total cellular carbon was small but varied 20 fold from 0.28 % to 5.17 %, and no obvious taxonomic pattern in the content of EDOC was appreciable for the species tested. The cell release rate of EDOC is small compared to the amount of carbon in the cell and difficult to capture. Nonetheless, the results point to a potential flux of volatile and semivolatile phytoplankton-derived organic carbon to the atmosphere that has been largely underestimated and deserves further attention in the future.

Inter-relationship Between Phytoplankton Cell Volume and Aquatic Salinity in Indian Sundarbans

Cell volumes of phytoplankton collected from 12 different stations distributed in western and central Indian Sundarbans were estimated through calculation of similar type of geometric models. 12 geometric shapes have been assigned to calculate the cell volume of 47 phytoplankton species documented during the study period. The cell volume of the observed species was more in the western sector (112.89–269383.60 μm3) compared to the central sector (108.37–225131.20 μm3). Among 47 species recorded during December 2011, cell volumes of 6 species exhibited significant inverse relationships, and 2 species exhibited significant positive relationships with aquatic salinity. Our results suggest that cell volume of certain phytoplankton species can be used as indicator of aquatic salinity.

Phytoplankton community reorganization driven by eutrophication and warming in Lake Biwa

We compiled and analyzed long-term data, including chemical, physical and phytoplankton community data, for the Lake Biwa ecosystem from 1962 to 2003. Analyses on environmental data indicate that Lake Biwa had experienced intensified eutrophication (according to total phosphorus concentration) in the late 1960s and returned to a less eutrophic status around 1985, and then exhibited rapid warming and thus increased water column stability since 1990. Total phytoplankton cell volume largely followed the trend of total phosphorus concentration, albeit short-term fluctuations existed. However, phytoplankton community shifted dramatically in response to those changes of environmental states. These shifts were cause by changes in trophic status driven by phosphorus loadings and physical properties in the water column driven by warming. Moreover, most phytoplankton species did not show a strong linear correlation with environmental variables, suggesting nonlinear transitions among different states.

Temporal variations of surface phytoplankton, nutrients and chlorophyll a in the Dardanelles (Turkish Straits System): a coastal station sample in weekly time intervals

In this study, weekly distributions of inorganic nutrients and phytoplankton cell volumes were investigated in relation to the hydrology of the Dardanelles. The data were collected between March 2001 and March 2002. NO^{-}_{2}+NO^{-}_{3}, PO_{4}^{-3}, and SiO_4 concentrations ranged between 0.050-6.887 µM, 0.051-1.152 µM, and 0.64-10.74 µM, respectively. During the study, the highest nutrient values were measured between late fall and mid-winter. Inorganic N:P and Si:P ratios in the surface water were lower due to high PO_{4}^{-3} concentrations. The chlorophyll a concentrations ranged from 0.03 to 8.67 µg L^{-1}. Phytoplankton cell density and cell volume ranged from 1.54E + 05 to 6.46E + 07 cell L^{-1} (mean 7.65E + 06; SD 1.44E + 07 cell L^{-1}) and from 2.51E + 09 to 8.66E + 10 µm^{-3} L^{-1} (mean 1.98E + 10; SD 1.86E + 10 µm^{-3} L^{-1}) between less productive and high productive periods. During the study period, 8-10 species controlled the phytoplankton community structure in the coastal zone of the Dardanelles. Others did not contribute to the phytoplankton population and they only can be considered as accessory species, which do not cause significant fluctuations in the phytoplankton production. Relationships between chlorophyll a, cell density, and cell volume of phytoplankton revealed that chlorophyll a is rather controlled by the cell density than by the cell volume. Furthermore, the physicochemical variables, such as nutrients and chlorophyll a and phytoplankton cell density and cell volume, are affected by the counter flows in the Dardanelles. Phytoplankton population was more limited by nitrogen than by phosphate due to extra phosphate inputs coming from various sources, such as domestic waste waters as well as the vertical mixing between upper and lower layers.

Effects of brown tide (Aureococcus anophagefferens) on hard clam Mercenaria mercenaria larvae and implications for benthic recruitment

Brown tides of Aureococcus anophagefferens occur in shallow mid-Atlantic bays in the USA and attain peak summer densities of ~1000 to 2800 cells µl -1 . Blooms coincide with the period of spawning and planktotrophic larval development of the hard clam Mercenaria mercenaria, a com- mercially important bivalve in the region. This laboratory study investigates the effects of A. anophagefferens (toxic isolate from Provasoli-Guillard Center for Culture of Marine Phytoplank- ton (CCMP 1708)) on hard clams throughout their larval development as a function of increasing (1) supplement and (2) contributor to total phytoplankton cell volume in the diet. Brown tide consistently inhibited veliger growth rates in a dose-dependent manner, leading to arrested development in the D-stage; yet mortalities varied greatly among larval batches and were attributed to secondary effects of nutritional stress. Growth of larvae exposed for 2 wk to brown tide at 800 cells µl -1 was 89 to 90% less than controls fed Isochrysis galbana (clone T-iso) in both the presence and absence of alternate food. No recovery was observed when larvae were returned to the control diet. However, larvae showed variable intrapopulation susceptibility to brown tide when exposed to a mixed suspension of A. anophagefferens and I. galbana (400 and 50 cells µl -1 , respectively). Exposure to low levels of brown tide (50 cells µl -1 ) resulted in relatively small but significant growth reduction. Larvae had reduced larval clearance rates (ingestion) when exposed to unialgal brown tide, as confirmed by analysis of gut autofluorescence and negative feeding selectivity for A. anophagefferens in a mixed suspension. Therefore, primarily through their inhibitory effects on growth, brown tides at ≥200 cells µl -1 are expected to cause metamorphic failure of hard clam larval populations. These will lead to extended larval life in the plankton and increased vulnerability to secondary mortality factors. In turn, hard clam larvae are expected to make a negligible contribution to microzooplankton grazing on brown tide.

Physical-Biological Coupling in Southern Lake Michigan: Influence of Episodic Sediment Resuspension on Phytoplankton

The influence of episodic, sediment resuspension on phytoplankton abundance/volume and composition, the photosynthetic maximum rate (PB max) and efficiency (αB), and chlorophyll-specific growth (μChl) was evaluated during the spring isothermal period in southern Lake Michigan (Laurentian Great Lakes, USA). Resuspension altered the nutrient and light climate of nearshore waters; light attenuation (Kd) and phosphorus concentrations corresponded (p ≤ 0.0001 and p ≤ 0.001, respectively) with concentrations of suspended particulate matter (SPM). Phytoplankton cell volume and diatom cell abundance and volume were not associated with SPM concentrations (p > 0.05). Diatom composition displayed spatial dissimilarities corresponding with resuspension (p ≤ 0.001); small centric diatoms exhibiting meroplanktonic life histories and pennate diatoms considered benthic in origin were most abundant within SPM-impacted, nearshore waters whereas taxa typically comprising assemblages in optically-clear, offshore waters and the basin-wide, spring bloom were not. Values of PB max and αB corresponded (p ≤ 0.0001) with both Kd coefficients and SPM concentrations, potentially reflecting increased light harvesting/utilization within impacted assemblages. However, integral production was inversely associated with Kd coefficients and SPM concentrations (p < 0.0001) and photosynthesis was light-limited (or nearly so) for most assemblages. Although μChl values corresponded with Kd coefficients (p ≤ 0.05), values were quite low (x ± S.E., 0.10 ± 0.004 d-1) throughout the study. Most likely, distinct rate processes between SPM- and non-impacted assemblages reflected short-term compositional (and corresponding physiological) variations due to infusion of meroplankton and/or tributary-derived phytoplankton. Overall, resuspension appears to have little, if any, long-term impact upon the structure and function of the lake’s phytoplankton.

Phytoplankton functional attributes along trophic gradient and season

Each of the following phytoplankton functional attributes could be described by significant (P &lt; 0.05) response surfaces defined by trophic status (T) from oligotrophy to hypertrophy and season (S) from early vernal period to late summer: phytoplankton cell volume, growth rate, the ratio between minimum quotas of total N and total P, affinity for P, half‐saturation constant for growth with respect to P, and temperature optimum and light optimum for growth. Sinking rate could not be so described. The response surfaces were calculated by multiple regressions, including first‐ and second‐order terms of T and S and the interaction term T · S. Although the data base was rather limited (number of phytoplankton species ranged from 10 to 31), the resulting surfaces often reflected a corresponding attribute of the water along T and S (e.g. phytoplankton temperature optimum for growth reflected water temperature). The results support the frequent use of physical factors as explanatory variables for the distribution and abundance of phytoplankton.

Comparative carbon-specific ingestion rates of phytoplankton by Acartia tonsa, Centropages velificatus and Eucalanus pileatus grazing on natural phytoplankton assemblages in the plume of the Mississippi River (northern Gulf of Mexico continental shelf)

During four cruises in continental shelf waters of the northern Gulf of Mexico in the winters of 1981–83, we performed quantitative studies on the grazing of the copepods Acartia tonsa, Centropages velificatus, and Eucalanus pileatus, on phytoplankton using natural particulate assemblages as food. Stations were in, or adjacent to the plume of the Mississippi River, thereby providing wide spectra of phytoplankton and suspended riverine particulate concentrations. Phytoplankton cell volume was converted to carbon, and this, coupled with carbon content measurements of these three copepod species, allowed comparisons of daily ingestion effort even though the copepods were of different sizes. Data were expressed in the same units (% of copepod body carbon ingested copepod −1 d−1) for each species. Over similar ranges of phytoplankton carbon concentrations (0.21–92.06 μgCl−1), Acartia tonsa had higher carbon-specific ingestion rates (x = 22.31%, range = 0.08–152.37%) than C. velificatus (x = 2.8%, range = 0.00–31.09 %) or E. pileatus (x = 1.27%, range = 0.10–2.80%). Carbon-specific ingestion rates increased with increasing phytoplankton carbon concentration for A. tonsa (R2 = 0.81) and there was no evidence of saturated feeding on the carbon concentrations offered. A similar, but weaker trend was evident for E. pileatus (R2 = 0.71), but not C. velificatus (R2 = 0.49). Over a wide range of suspended particulate concentrations (10.6–95.2 mg l−1), there was no systematic effect of particulates on carbon-specific ingestion rate for any of the three copepod species. However, A. tonsa appeared more adept at grazing in highly turbid water than C. velificatus or E. pileatus.

The influence of whole lake aeration on the limnology of a hypereutrophic lake in central Florida

To determine the influence of a multiple inversion aeration system upon the limnology of a small sinkhole lake, we monitored physical-chemical and biological parameters for 15 months prior to starting aeration and for 24 months thereafter. Aeration eliminated thermal stratification and dissolved oxygen concentrations of bottom waters increased significantly. Secchi disk transparency increased during aeration while turbidity, pH, alkalinity, total nitrogen, hydrogen sulfide and iron concentrations decreased significantly. Primary production and mean chlorophyll a did not change significantly during aeration but total phytoplankton cell volume decreased 2-fold. This decrease was caused by a marked reduction in blue-green algae which appears to be attributable to rapid mixing of the lake and to decreases in the pH. Cell volumes of green algae remained constant but numbers of taxa increased 70%. Densities of crustacean zooplankton were reduced markedly by aeration while densities of rotifers increased significantly during the first year but then returned to preaeration levels during the second year. Large-bodied cladocerans were replaced by small-bodied forms during aeration, and copepod populations became dominated by nauplii (97%). Densities of benthic macroinvertebrates declined 2-fold during aeration due to to a marked reduction (10-fold) in the Chaoborus population which correlated strongly with decreases in crustacean zooplankton abundance. The total number of taxa collected on individual sample dates increased throughout the two year aeration period (from 12 to 25) and chironomids became the predominant group (70%).

Limnological Characteristics of Two Eutrophic and Four Mesotrophic Lakes in West‐central Florida

AbstractLimnological characteristics of six subtropical lakes were monitored to determine the factors which regulate chlorophyll α concentrations and phytoplankton standing crops. Most physical chemical variables showed non‐significant differences with depth but differences between lakes often were large. Phytoplankton blooms occurred throughout the year and there were marked differences between the hypereutrophic and mesotrophic lakes in chlorophyll α concentrations, standing stocks, and dominant species. Densities of total zooplankton and rotifers in the hypereutrophic lakes were 3‐ to 6‐fold greater than in the mesotrophic lakes. Regression models for chlorophyll α and total phytoplankton cell volume were calculated for each lake and for all lakes combined, but R2 values and numbers of shared variables tended to be low indicating the need for additional variables and more frequent sampling.

An Examination of Cell Volume in Dominant Phytoplankton Species of the Central and Southern Adriatic Sea

AbstractThe phytoplankton biomass expressed as total cell volume is often of doubtful value due to cell size and volume variations in the organisms present. Cell volume calculations for 95 phytoplankton species and volume‐frequency diagrams for 25 dominant species were analyzed for the Adriatic Sea. Recommendations for more precise work dealing with phytoplankton cell volume and biomass are given. Temporal variations in the average microplankton cell volume are presented and discussed.

Comparison of phytoplankton concentrations and cell volume measurements from the continental shelf off Cape Cod, Massachusetts, U.S.A.

Phytoplankton composition and concentrations varied at stations across the shelf with maximum phytoplankton volumes not necessarily related to maximum concentration values. The shelf phytoplankton off Cape Cod, Massachusetts was composed of two major size classes: the ultraplankton (cells less than 10 microns in size), and net phytoplankton. Cell concentrations decreased along transects seaward, to increase near the shelf margin. Higher cell volume values coincided with increased cell counts east of Cape Cod, but were lower southward, increasing in the mid-shelf region, to decrease along the shelf margin. The shelf ultraplankton component typically represented over 90% of the standing crop, but less than 1% of its phytovolume. Associations are made between cell volumes and concentration combinations and different phytoplankton assemblages.

Chlorophyllaas an indicator of phytoplankton cell volume in 12 lakes, North Island, New Zealand

Abstract The relationship between measurements of phytoplankton cell volume (CV) and chlorophyll a (Chla) in the near surface waters (1 m) of 12 North Island lakes was investigated between January and December 1982 to determine the usefulness of Chla as a biomass indicator. A strong linear relationship was obtained between the two parameters (F = 262, n = 131) which explained 66% of the variation. There was a distinct seasonal trend, however, in the amount of chlorophyll a measured per unit algal cell volume (Chla/CV). Values of Chla/CV ranged between .1.9 and .12.4 μg.mm-1 and were generally high dunng the wlO.ter (interquartile range 6.6-10.5, n = 33) and low dunng the summer (interquartile range 2.8-3.9, n = 47). When this effect was taken into account, the explanatory power of the Chla-CV relationship increased to 78%. This relationship was not significantly affected by changes in phytopla~kton taxonomic composition (i.e., Bacillariophyceae Chlorophyceae, Dinophyceae), and reliably predicts either Chl...

Statistical Analysis of the Spatial and Temporal Variability of the Ratio Chlorophyll A to Phytoplankton Cell Volume in Saginaw Bay, Lake Huron

Chlorophyll a has traditionally been used as an indicator of phytoplankton concentration in natural waters. This parameter has also been widely used by phytoplankton modelers for the purpose of comparing model output with field data. Examination of 1974 field data from Saginaw Bay indicated that chlorophyll a concentrations were inconsistent with phytoplankton cell volume concentrations. Statistical procedures were employed to determine the significance and source of the observed variability in the ratio of chlorophyll a to cell volume concentrations. The procedures employed included t-tests, analysis of variance and polynomial regression. The hypothesis that the natural log of the ratio of chlorophyll a to cell volume was constant in time was tested on six different sampling station groupings representing various spatial divisions of Saginaw Bay. In all cases, this ratio was found to vary significantly at the 95% confidence level. The variability of the ratio decreased when only data from the outer portion of Saginaw Bay were used. Greater than 60% of the variability of the ratio can be removed by using a linear correlation of the natural log chlorophyll a to cell volume ratio with the fraction of diatom cell volume.

A comparison of different methods used for the quantitative evaluation of biomass of freshwater phytoplankton

Although in a strict sense the term ‘phytoplankton biomass’ only refers to living algal material, in aquatic ecology the term has been associated with a variety of biological and biochemical procedures used to quantify the particulate matter suspended in natural waters. Relative merits of different ‘biomass’ characteristics have been studied in three Dutch freshwater lakes with great differences in absolute biomass. Parallel determinations have been made of seston dry weight and supplementary elementary and caloric analyses of seston, of chlorophyll-a concentration and supplementary paper chromatographic analyses of pigment extracts, of particle concentration and particle size distribution as studied with an electronic particle counter, and of phytoplankton cell volume as calculated from the results of microscopic enumeration and sizing of algae. In this way an attempt was made to create a detailed picture of the nature of the seston of the three freshwater lakes. Different analytical techniques give strikingly different information, the accuracy of any method is largely dependent on the circumstances present, and different biomass characteristics therefore are only of value in limited spheres. It is suggested to distinguish between total seston characteristics (e.g. seston dry weight, particulate organic carbon, total particle volume) and strictly algological biomass characteristics (e.g. chlorophyll-a concentration, phytoplankton cell volume). The pattern of growth of phytoplankton populations shown by e.g. chlorophyll-a concentration may differ markedly from that indicated by e.g. total particle volume or seston dry weight. Also, to more or less extent the wax and wane of phytoplankton populations may go undetected among the total seston. Apparently, there is no one method of estimating biomass and no conversion factor that may serve for general purposes. In general, unambiguous information on the nature of the seston of natural waters may only be obtained by estimating total seston characteristics and algological biomass characteristics simultaneously. Depending on the objective of the investigation supplementary component analyses should be carried out to guarantee the correct interpretation of the results.