Biochemical Composition Of Phytoplankton Research Articles

Spatio-temporal Distribution and Biochemical Composition of Phytoplankton along the Coastal Waters of Dakshin Kannada District, Karnataka, India

The phytoplankton distribution and biochemical composition concerning water quality parameters were studied in the coastal waters off Mangalore, Monthly sampling was carried out from October 2020 to May 2022 at selected stations of Netravathi-Gurupura estuary, latitude 12°50'38.56" N, longitude 74°50'0.23° to coastal waters off Padubidri latitude 13° 8'0. 57" N longitude 74°42'9.47° with an average depth of 8 meters. Spatiotemporally the phytoplankton, chlorophyll-a and phytoplankton biochemical composition showed a significant difference for the entire duration. During the present investigation, 35 different phytoplankton genera belonging to 3 groups were observed with complete domination from diatoms with 27 genera followed by Dinoflagellates 7 and blue-green algae. distribution and abundance of the phytoplankton were mainly Chaetoceros sp., Ceratium sp., Thallasiocera sp., Biddulphia sp., Coscinodiscus sp., Rhizosolenia sp., Ditylum sp., Triceratium sp., Nitzschia sp. and blue-green algae under Chrysophyta, Bryophyta, Chlorophyta, Cyanophyta were observed, while in biochemical composition of phytoplankton, the carbon contributed to the highest percentage and hydrogen constitute to the lowest percentage. Crude protein and Lipid contents are maximum during post-monsoon and carbohydrates showed their highest content during pre-monsoon for phytoplankton. There is a direct relationship between the biochemical composition and the physiochemical and environmental conditions including nutrients, especially nitrates and phosphates.

THE EFFECT OF N/P RATIO OF UREA AND TSP FERTILIZERS IN WALNE MEDIA ON THE GROWTH PATTERN OF AND PROTEIN CONTENT OF Thalassiosira Sp. DIATOM CELLS

The availability of natural feed needed in hatchery business is very significant due to the fact that natural feed will help the hatchery process to produce good and hi-quality seeds. Thalassiosira sp. is a type of diatom phytoplankton widely used to feed shrimp larvae. Walne media is a medium commonly used in the process of phytoplankton culture. Nutrient has considerable effect on the biochemical composition of phytoplankton, such as the content of protein, amino acids, carbohydrates, fats, and fatty acids. Nitrates and phosphorus contained in water are the main nutrients for phytoplankton to produce chlorophyll. One of the fertilizers which can be used for phytoplankton culture is agricultural fertilizers such as urea and TSP. The aims of this study were (1) to examine the effect of the application of the N/P ratio of urea and TSP in Walne media on the growth pattern and protein content of Thalassiosira sp. diatom cells; and (2) to determine the best value of the N/P ratio of urea and TSP fertilizers in Walne media which provides growth patterns and protein content of diatom cells of Thalassiosira sp. The method used in this research was an experimental method. The experimental method used was a completely randomized design (CRD) with 5 treatments and 4 designs, each treatment was as follows: applying different N/P ratios of urea and TSP fertilizers in Walne media, i.e. (A) 1:1; (B) 4:1; (C) 8:1; (D) 12:1; and (E) 16:1. The results of this study showed that algae growth increased from 0:0 to 16:0 N:P ratio. The growth of diatoms with the highest density occurred in treatments A and B with cell densities of 2.255×106 to 2.256×106 cells/ml compared to the other N:P ratios. It can be concluded the 1:1 N/P ratio of urea and TSP fertilizers in Walne media had a significant effect on growth patterns and protein content of diatom cells of Thalassiosira sp.

Spatial Patterns of Macromolecular Composition of Phytoplankton in the Arctic Ocean

The macromolecular concentrations and compositions of phytoplankton are crucial for the growth or nutritional structure of higher trophic levels through the food web in the ecosystem. To understand variations in macromolecular contents of phytoplankton, we investigated the macromolecular components of phytoplankton and analyzed their spatial pattern on the Chukchi Shelf and the Canada Basin. The carbohydrate (CHO) concentrations on the Chukchi Shelf and the Canada Basin were 50.4–480.8 μg L−1 and 35.2–90.1 μg L−1, whereas the lipids (LIP) concentrations were 23.7–330.5 μg L−1 and 11.7–65.6 μg L−1, respectively. The protein (PRT) concentrations were 25.3–258.5 μg L−1 on the Chukchi Shelf and 2.4–35.1 μg L−1 in the Canada Basin. CHO were the predominant macromolecules, accounting for 42.6% on the Chukchi Shelf and 60.5% in the Canada Basin. LIP and PRT contributed to 29.7% and 27.7% of total macromolecular composition on the Chukchi Shelf and 30.8% and 8.7% in the Canada Basin, respectively. Low PRT concentration and composition in the Canada Basin might be a result from the severe nutrient-deficient conditions during phytoplankton growth. The calculated food material concentrations were 307.8 and 98.9 μg L−1, and the average calorie contents of phytoplankton were 1.9 and 0.6 kcal m−3 for the Chukchi Shelf and the Canada Basin, respectively, which indicates the phytoplankton on the Chukchi Shelf could provide the large quantity of food material and high calories to the higher trophic levels. Overall, our results highlight that the biochemical compositions of phytoplankton are considerably different in the regions of the Arctic Ocean. More studies on the changes in the biochemical compositions of phytoplankton are still required under future environmental changes.

Seasonal Variations in the Biochemical Compositions of Phytoplankton and Transparent Exopolymer Particles (TEPs) at Jang Bogo Station (Terra Nova Bay, Ross Sea), 2017–2018

The biochemical composition of particulate organic matter (POM) mainly originates from phytoplankton. Transparent exopolymer particles (TEPs) depend on environmental conditions and play a role in the food web and biogeochemical cycle in marine ecosystems. However, little information on their characteristics in the Southern Ocean is available, particularly in winter. To investigate the seasonal characteristics of POM and TEPSs, seawater samples were collected once every two weeks from November 2017 to October 2018 at Jang Bogo Station (JBS) located on the coast of Terra Nova Bay in the Ross Sea. The total chlorophyll-a (Chl-a) concentrations increased from spring (0.08 ± 0.06 μg L−1) to summer (0.97 ± 0.95 μg L−1) with a highest Chl-a value of 2.15 μg L−1. After sea ice formation, Chl-a rapidly decreased in autumn (0.12 ± 0.10 μg L−1) and winter (0.01 ± 0.01 μg L−1). The low phytoplankton Chl-a measured in this study was related to a short ice-free period in summer. Strong seasonal variations were detected in the concentrations of proteins and lipids (one-way ANOVA test, p < 0.05), whereas no significant difference in carbohydrate concentrations was observed among different seasons (one-way ANOVA test, p > 0.05). The phytoplankton community was mostly composed of diatoms (88.8% ± 11.6%) with a large accumulation of lipids. During the summer, the POM primarily consisted of proteins. The composition being high in lipids and proteins and the high caloric content in summer indicated that the phytoplankton would make a good food source. In winter, the concentrations of proteins decreased sharply. In contrast, relatively stable concentrations of carbohydrates and lipids have been utilized for respiration and long-term energy storage in the survival of phytoplankton. The TEPS values were significantly correlated with variations in the biomass and species of the phytoplankton. Our study site was characterized by dominant diatoms and low Chl-a concentrations, which could have resulted in relatively low TEP concentrations compared to other areas. The average contributions of TEP-C to the total POC were relatively high in autumn (26.9% ± 6.1%), followed by those in summer (21.9% ± 7.1%), winter (13.0% ± 4.2%), and spring (9.8% ± 3.1%).

Monthly Variation in the Macromolecular Composition of Phytoplankton Communities at Jang Bogo Station, Terra Nova Bay, Ross Sea.

Organic carbon fixed by photosynthesis of phytoplankton during the polar growing period could be important for their survival and consumers during the long polar night. Differences in biochemical traits of phytoplankton between ice-free and polar night periods were investigated in biweekly water samples obtained at the Korean “Jang Bogo Station” located in Terra Nova Bay, Antarctica. The average concentration of total Chl-a from phytoplankton dominated by micro-sized species from the entire sampling period was 0.32 μg L–1 (SD = ± 0.88 μg L–1), with the highest concentration of 4.29 μg L–1 in February and the lowest concentration of 0.01 μg L–1 during the ice-covered polar night (April–October) in 2015. The highest protein concentration coincided with the peak Chl-a concentration in February and decreased rapidly relative to the carbohydrate and lipid concentrations in the early part of polar night. Among the different biochemical components, carbohydrates were the predominant constituent, accounting for 69% (SD = ± 14%) of the total particulate organic matter (POM) during the entire study period. The carbohydrate contributions to the total POM markedly increased from 39 ± 8% during the ice-free period to 73 ± 9% during the polar night period. In comparison, while we found a significant negative correlation (r2 = 0.92, p < 0.01) between protein contributions and carbohydrate contributions, lipid contributions did not show any particular trend with relatively small temporal variations during the entire observation period. The substantial decrease in the average weight ratio of proteins to carbohydrates from the ice-free period (mean ± SD = 1.0 ± 0.3) to the ice-covered period (mean ± SD = 0.1 ± 0.1) indicates a preferential loss of nitrogen-based proteins compared to carbohydrates during the polar night period. Overall, the average food material (FM) concentration and calorific contents of FM in this study were within the range reported previously from the Southern Ocean. The results from this study may serve as important background data for long-term monitoring of the regional and interannual variations in the physiological state and biochemical compositions of phytoplankton resulting from future climate change in Antarctica.

Different Biochemical Compositions of Particulate Organic Matter Driven by Major Phytoplankton Communities in the Northwestern Ross Sea.

Marine particulate organic matter (POM) largely derived from phytoplankton is a primary food source for upper trophic consumers. Their biochemical compositions are important for heterotrophs. Especially, essential amino acids (EAAs) in phytoplankton are well known to have impacts on the survival and egg productions of herbivorous zooplankton. To estimate the nutritional quality of POM, the biochemical compositions [biomolecular and amino acid (AA) compositions] of POM were investigated in the northwestern Ross Sea during the late austral summer in 2018. Carbohydrates (CHO) accounted for the highest portion among different biomolecules [CHO, proteins (PRT), and lipids (LIP)] of POM. However, the higher contribution of PRT and lower contribution of CHO were observed in the southern section of our study area compared to those in the northern section. The spatial distribution of total hydrolyzable AAs in POM was considerably influenced by phytoplankton biomass, which indicates that the main source of particulate AA was generated by phytoplankton. Our results showed that the relative contribution of EAA to the total AAs was strongly associated with EAA index (EAAI) for determining protein quality. This result indicates that higher EAA contribution in POM suggests a better protein quality in consistency with high EAAI values. In this study, variations in the biochemical compositions in POM were principally determined by two different bloom-forming taxa (diatoms and Phaeocystis antarctica). The southern region dominated majorly by diatoms was positively correlated with PRT, EAA, and EAAI indicating a good protein quality, while P. antarctica-abundant northern region with higher CHO contribution was negatively correlated with good protein quality factors. Climate-driven environmental changes could alter not only the phytoplankton community but also the physiological conditions of phytoplankton. Our findings could provide a better understanding for future climate-induced changes in the biochemical compositions of phytoplankton and consequently their potential impacts on higher trophic levels.

Major controlling factors for spatio-temporal variations in the macromolecular composition and primary production by phytoplankton in Garolim and Asan bays in the Yellow Sea

Little information on phytoplankton is currently available for Garolim and Asan bays, which are important spawning and nursery grounds for various commercial fish. The objectives of this study were to investigate the spatial and seasonal variations in the biochemical components (carbohydrates, proteins, and lipids) and primary production by phytoplankton and to determine the major environmental factors controlling the variations in Garolim and Asan bays. All major inorganic nutrients were seasonally available to phytoplankton although PO4 concentrations were relatively lower than those of other nutrients. The chlorophyll-a (chl-a) concentration measured in this study was within the range reported previously and the phytoplankton community was mostly dominated by micro- and nano-phytoplankton (approximately 80 %). Among the different biochemical compositions, carbohydrates were the most dominant throughout our observation period. As a nitrogen source for phytoplankton growth, ammonium was more important compared to nitrate in Garolim and Asan bays because of a significantly high uptake rate of the ammonium observed in this study. The overall mean areal daily carbon uptake rate (238.8 ± 393.3 mg C m−2 d−1) measured in this study is within the range in various bays and coastal waters in Korea. The concentrations of SiO2, NO2+NO3 and micro-sized chl-a were found to be major factors for the variation in the biochemical compositions of phytoplankton. By comparison, the nano-sized chl-a concentration, NH4 concentration and temperature were observed to be major factors in the variation in the carbon uptake rate of phytoplankton in Garolim and Asan bays during our observation period. Further studies on macromolecular compositions and primary production from different cell-sized phytoplankton are warranted for a better understanding their potential effects on marine ecosystems.

The biochemical composition of phytoplankton in the Laptev and East Siberian seas during the summer of 2013

The Laptev and East Siberian seas which are generally viewed as terrestrial organic matter (TerrOM)-dominated seas, are among the least biologically understood regions in the Arctic Ocean. During the summer of 2013, however, the TerrOM signature was negligible in our samples. We investigated the biochemical composition (carbohydrates [CHO], proteins [PRT], and lipids [LIP]) of phytoplankton-dominated particulate organic matter in order to improve our understanding of the physiological status of resident phytoplankton. Our chlorophyll-a values and the presence of SCMs and resting spores were associated with a cessation of the phytoplankton bloom. Despite the low inorganic nitrogen nutrients in the water column, the cellular PRT (39%) were comparable to CHO (42%) contents and the inorganic (dissolved nitrogen:dissolved phosphate) and organic (PRT:CHO) indices did not indicate a nitrogen stress of phytoplankton metabolism. Altogether, the phytoplankton were likely in a growth transition from the exponential to the stationary phase, resulting in CHO-dominated cells with moderate PRT. By comparing our biochemical analyses with the LIP-dominated (> 50%) ones in the Chukchi Sea (the summers of 2011 and 2012), we conclude that more severe nitrogen-limited conditions occurred in the Chukchi Sea. In a quality aspect, we suggest that consumers which feed on LIP-rich phytoplankton could have an advantage to overwinter while those feeding on CHO-rich phytoplankton will gain energy efficiently in a short term. Therefore, the biochemical composition of phytoplankton could be a valid integrator of surrounding environments in which phytoplankton grow and can be a good indicator of their nutritional value.

Carbohydrate-dominant Phytoplankton and Protein-high Zooplankton in the Northern Part of the Southwestern East/Japan Sea in 2015

ABSTRACT Jo, N.; Kang, J.J.; Park, W.G.; Lee, B.R.; Lee, J.H.; Kim, Y.; Ahn, S.H.; Lee, D.; Min, J.-O.; Kang, C.-K., and Lee, S.H., 2018. Carbohydrate-dominant phytoplankton and protein-high zooplankton in the northern part of the southwestern East/Japan Sea in 2015. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 371–375. Coconut Creek (Florida), ISSN 0749-0208. The biochemical compositions of phytoplankton and zooplankton were monthly investigated in the northern part of the southwestern East/Japan Sea from May to October in 2015 except August. Among the biochemical compositions of phytoplankton, carbohydrate composition (55.5 ± 7.3%) was most dominant during the study period. A significant negative relationship (r = −0.855, p < 0.01, n = 39) was found between the carbohydrate and lipid compositions of phytoplankton in this study, which can be due to a switc...

Seasonal variation in the biochemical compositions of phytoplankton and zooplankton communities in the southwestern East/Japan Sea

The macromolecular composition of phytoplankton communities and the proximate composition of zooplankton communities were measured monthly in the southwestern East/Japan Sea from April to November 2014 in order to identify seasonal changes in, and relationships among, the biochemical compositions in both phytoplankton and zooplankton. The carbohydrate content of phytoplankton was highest in June, whereas the protein content was highest in August and lipids were highest in April. Overall, carbohydrates were dominant (53.2 ± 12.5%) in the macromolecular composition of phytoplankton during the study period. This composition is believed to result from the dominance of diatoms and/or nutrient-depleted conditions. In comparison, the protein level of zooplankton was highest in November, whereas lipids were slightly higher in May than other months. Overall, proteins were the dominant organic compounds (47.9±8.6% DW) in zooplankton communities, whereas lipids were minor components (5.5±0.6% DW). The high protein content of zooplankton might be related to the abundance of copepods, whereas the low lipid content might be due to a relatively high primary production that could provide a sufficient food supply for zooplankton so that they do not require high lipid storage. A significant positive correlation (r=0.971, n=7, p<0.01) was found between the lipid compositions of phytoplankton and zooplankton during our study period with a time lag, which is consistent with the findings from previous studies. More detailed studies on the biochemical composition of phytoplankton and zooplankton are needed to better understand the East/Japan Sea ecosystem's response to the many environmental changes associated with global warming.

Partitioning the Relative Importance of Phylogeny and Environmental Conditions on Phytoplankton Fatty Acids.

Essential fatty acids (EFA), which are primarily generated by phytoplankton, limit growth and reproduction in diverse heterotrophs. The biochemical composition of phytoplankton is well-known to be governed both by phylogeny and environmental conditions. Nutrients, light, salinity, and temperature all affect both phytoplankton growth and fatty acid composition. However, the relative importance of taxonomy and environment on algal fatty acid content has yet to be comparatively quantified, thus inhibiting predictions of changes to phytoplankton food quality in response to global environmental change. We compiled 1145 published marine and freshwater phytoplankton fatty acid profiles, consisting of 208 species from six major taxonomic groups, cultured in a wide range of environmental conditions, and used a multivariate distance-based linear model to quantify the total variation explained by each variable. Our results show that taxonomic group accounts for 3-4 times more variation in phytoplankton fatty acids than the most important growth condition variables. The results underscore that environmental conditions clearly affect phytoplankton fatty acid profiles, but also show that conditions account for relatively low variation compared to phylogeny. This suggests that the underlying mechanism determining basal food quality in aquatic habitats is primarily phytoplankton community composition, and allows for prediction of environmental-scale EFA dynamics based on phytoplankton community data. We used the compiled dataset to calculate seasonal dynamics of long-chain EFA (LCEFA; ≥C20 ɷ-3 and ɷ-6 polyunsaturated fatty acid) concentrations and ɷ-3:ɷ-6 EFA ratios in Lake Washington using a multi-decadal phytoplankton community time series. These analyses quantify temporal dynamics of algal-derived LCEFA and food quality in a freshwater ecosystem that has undergone large community changes as a result of shifting resource management practices, highlighting diatoms, cryptophytes and dinoflagellates as key sources of LCEFA. Moreover, the analyses indicate that future shifts towards cyanobacteria-dominated communities will result in lower LCEFA content in aquatic ecosystems.

Macromolecular compositions of phytoplankton in the Amundsen Sea, Antarctica

The biochemical compositions (proteins, carbohydrates, and lipids) of phytoplankton provide useful information for their environmental growth conditions and nutritional status as a basic food source for upper trophic consumers. Concentrations of these compositions were assessed at 100, 30, and 1% light penetration depths within the euphotic zone in the Amundsen Sea, Antarctica, using colorimetric techniques. The major inorganic nutrients were generally abundant throughout the study area. The average chlorophyll a (chl-a) concentration was 49.2mgm−2 (S.D.=±27.6mgm−2) and large phytoplankton (>20µm) accounted for 64.1% of the total chl-a concentration. The biochemical compositions of the phytoplankton were not significantly different among different light depths or productivity stations. The overall compositions of proteins, carbohydrates, and lipids from all stations averaged 65.9% (S.D.=±12.5%), 22.4% (S.D.=±10.9%), and 11.7% (S.D.=±6.5%), respectively. Regardless of dominant phytoplankton species, nitrogen-abundant conditions sustained high protein compositions of phytoplankton in the Amundsen Sea during the cruise period. Based on the macromolecular compositions, the average food material (FM) concentration was 219.4μgL−1 (S.D.=±151.1μgL−1) and correlated positively with the primary productivity in the Amundsen Sea. High protein/carbohydrate ratios (>1) and large proportions of proteins suggest that phytoplankton provide nitrogen-sufficient foods to higher trophic consumers through a higher efficiency of protein carbon incorporated into herbivores.

Comparison of phytoplankton macromolecular compositions and zooplankton proximate compositions in the northern Chukchi Sea

The macromolecular (proteins, lipids, and carbohydrates) composition of phytoplankton and the proximate (water, proteins, lipids, and ash) and elemental (carbon and nitrogen) compositions of mesozooplankton were determined in the northern Chukchi Sea to establish the relationship between zooplankton and their phytoplankton food source. Among the phytoplankton macromolecules examined in this study, lipids had the highest contents (58.4±8.2%) and proteins had the lowest (16.1±7.3%), which may be a consequence of a nitrogen deficiency in phytoplankton growth during the study period. In contrast, proteins (59.7±10.6% DW) were the major proximate components in the mesozooplankton community, which was dominated by copepods up to 71% of total abundance. The low lipid contents (13.8±12.4% DW) in the mesozooplankton community in this study might be due to the dominance of small species such as Calanus glacialis, which generally have relatively lower lipid contents than large copepods. Moreover, the spawning period of C. glacialis from April to June might be an additional reason for the low lipid contents, because copepods have normally very low lipid contents after spawning. The low lipid contents resulted in a low energy content in this mesozooplankton community in the northern Chukchi Sea. The different biochemical compositions of phytoplankton and zooplankton should be considered in order to understand the impacts of climate change on the quality of prey provided by lower trophic levels and subsequently on Arctic marine ecosystems.

Effects of nutrient and light limitation on the biochemical composition of phytoplankton

Three marine phytoplankters (Isochrysis galbana, Chaetoceros calcitrans andThalassiosira pseudonana), commonly used in the culture of bivalve larvae, were grown in batch or semi-continuous cultures. Changes in protein, carbohydrate, lipid and some fatty acids were measured as growth became limited by nitrogen, silicon, phosphorus or light. Under N starvation (2 d) the % lipid remained relatively constant, while% carbohydrate increased and% protein decreased in all 3 species compared to cells growing under no nutrient limitation. Under Si starvation (6 h) there was no change in lipid, protein or carbohydrates. The amount of two fatty acids, 20 : 5ω3 and 22 : 6ω3 remained relatively constant under N, P and Si starvation, exept for a sharp drop in the cells of P-starvedT. pseudonana. However, there were pronounced species differences withI. galbana containing significantly less 20 : 5 ω3 thanC. calcitrans orT. pseudonana. Under light limitation the amount of lipid per cell showed no consistent trend over a range of irradiances for all 3 species. The amount of N per cell (an index of protein content) as a function of irradiance, was relatively constant forI. galbana andT. pseudonana, while the amount of N per cell was lower under low irradiances forC. calcitrans. These examples of changes in protein, carbohydrate, lipid and certain fatty acids under nutrient (N, Si or P) or light limitation, emphasize the importance of knowing the phase (e.g. logarithmic vs stationary) of the growth curve in batch cultures, since the nutritional value of the phytoplankters could change as cultures become dense and growth is terminated due to nutrient or light limitation.

A statistical method to estimate the biochemical composition of phytoplankton in the Southern Bight of the North Sea

The knowledge of changes in the biochemical composition of phytoplankton and its degraded products is regarded as important for the understanding of an eco-system because it influences the heterotrophic activities of the seawater column and/or sediments. The linear regressions method of some specific metabolite (protein, carbohydrate, lipid) on chlorophyll a is considered as the better method to estimate the biochemical composition of natural phytoplankton in the coastal area of the Southern Bight of the North Sea. The validity of this statistical method depends on a correct assemblage of the results in time and space, and requires a good knowledge of the growth conditions of the phytoplankton cells. This essential condition is however difficult to realize for post-bloom periods where the growth conditions are more heterogeneous. The linear regressions lead on the one hand to the quantification of two components of the total particulate organic matter (phytoplankton and bacteria/detritus) and on the other hand to their biochemical characterization. The comparison of the biochemical composition of the two components shows that bacteria/detritus component has an effective nutritive value when phytoplankton is less abundant. The study of the influence of changes in the environmental conditions (light intensity and nitrogen availability), on the biochemical composition of the phytoplankton shows a similar protein content of about 50% when nitrogen is not limiting. On the other hand, a change in the light intensity does not change the biochemical composition of natural phytoplankton but increases the cellular chlorophyll content when nitrogen is sufficient to ensure a good phytoplanktonic growth.

The biochemical composition of phytoplankton in an upwelling region off south Africa

Variations in the concentrations of chlorophyll a, ATP, protein, and carbohydrates in phytoplankton have been investigated in a nearshore upwelling region off the Cape Peninsula. During active upwelling temperatures <10 °C, high nutrient concentrations and low concentrations of the biochemical constituents were measured. When upwelling lessened and conditions stabilized temperatures increased and blooms of phytoplankton appeared. High concentrations of chlorophyll a and ATP and a high protein/carbohydrate ratio were then recorded. At very low nutrient levels chlorophyll a and ATP concentrations were still high but an increase in the acid-soluble carbohydrate content and a corresponding decrease in the protein/carbohydrate ratio was observe. It was concluded that the ratio of protein to carbohydrate was a suitable indicator of the physiological state of a phytoplankton community in the local upwelling region.