Variations In Phytoplankton Productivity Research Articles

Seasonal variations in phytoplankton productivity in a shallow cove in the eastern Seto Inland Sea, Japan

We examined phytoplankton productivity in Shido Bay, an active oyster farming area in the eastern Seto Inland Sea, Japan, by an in situ 13C method from March 2016 to January 2017. The depth-integrated daily phytoplankton production ranged from 0.13 to 1.61 g C m−2 day−1, and the estimated annual production was 218 g C m−2 year−1. The daily production peaked in the rainy season and autumn, when phytoplankton blooms were observed, and production during the bloom events largely contributed to the annual production. There was a strong correlation between daily production and phytoplankton biomass (chlorophyll a) throughout the study period. In the study area, due to the shallow depth (6 m) and moderate light attenuation coefficient of the water column (0.38 ± 0.07 m−1), the mean light intensity in the water column was maintained at high levels (36 ± 5% of incident photosynthetically active radiation) throughout the study period. In contrast, the dissolved inorganic nitrogen concentration of the water was persistently low (< 1.5 µM) from late winter to summer. As a consequence, an increase in nitrogen supply seemed to be the key factor causing the increases in daily production and directly triggering the phytoplankton blooms in the bay.

Effects of the interannual variability of water column stratification on phytoplankton production and biomass in the northern zone off Baja California

The ocean off the Baja California Peninsula (Mexico) has been affected by interannual processes. Some of these processes have produced changes in oceanic circulation and the atmosphere, which have been reflected in the structure of the water column. Stratification, defined as the amount of energy needed to mix water throughout the water column, determines nutrient availability in the euphotic zone for phytoplankton growth. The aim of this study is to describe and relate the interannual variations of phytoplankton production and biomass with changes in the structure of the water column. To this end, we analyzed time series (1997–2016) for integrated Chlorophyll a, integrated primary production, pycnocline depth, mixed layer depth, and stratification indices along line 100 of the Investigaciones Mexicanas de la Corriente de California (IMECOCAL) program. The results showed 2 periods of high stratification and a decrease in phytoplankton production and biomass off Baja California, corresponding to the intrusion of subarctic water and El Niño 2015–2016. Finally, by using generalized additive models, we related 2 photosynthethic parameters-maximum photosynthetic rate and maximum light utilization coefficient-with water stratification. These relationships explained interannual variations in phytoplankton production in terms of water column stratification. The time series and the analysis reported here for IMECOCAL line 100 could be used to extrapolate the effects of interannual physical processes on phytoplankton in other zones off the Baja California peninsula.

Large seasonal variation in phytoplankton production in the Amundsen Sea

To better estimate annual primary production in the Amundsen Sea, which is one of the highest productivity regions in the Southern Ocean, the seasonal variations in carbon and nitrogen uptake rates of phytoplankton were investigated in this study. Based on 13C–15N dual isotope tracer techniques, the average daily productivities for the Amundsen polynya (AP), Pine Island polynya (PIP) and non-polynya regions were 0.25, 0.16 and 0.12 g C m−2 day−1, respectively. The average daily uptake rates of total nitrogen were 60.2, 53.5 and 34.8 mg N m−2 day−1 for the AP, PIP and non-polynya stations, respectively. In spite of the high concentration of nitrate in the Amundsen Sea, daily nitrate uptake rates (mean ± SD = 0.02 ± 0.01 g N m−2 day−1) were lower than ammonium uptakes for all productivity stations in this study, which resulted in a significantly lower f-ratio (mean ± SD = 0.44 ± 0.24) than that (mean ± SD = 0.71 ± 0.15) of the previous year. The substantially lower uptake rates of carbon and nitrogen and the f-ratio, especially in the AP, are due to a large seasonal variation in the uptake rates mainly caused by the shorter daytime duration and partly due to lower light availability induced by deeper mixed conditions in the present study compared with the previous study in 2010/2011. The large seasonal variation in daily phytoplankton production should be considered to better estimate annual production as a basic food source for higher trophic levels in the Amundsen Sea.

Linking atmospheric dimethyl sulfide and the Arctic Ocean spring bloom

AbstractWe measured atmospheric dimethyl sulfide (DMS) mixing ratios at approximately hourly intervals over a 1 year period (April 2010 to March 2011) in the Atlantic sector of the Arctic Ocean (Svalbard, Norway; 78.5°N, 11.8°E). The mixing ratios varied by several orders of magnitude over time scales of less than several days, and occasionally reached 200−300 parts per trillion by volume during the major phytoplankton growth period (May to September), whereas during the winter months (October to April) the mixing ratios were on the order of a few parts per trillion by volume. Our results, based on analyses using multiple data products (atmospheric DMS mixing ratios, satellite‐derived ocean colors, and meteorological datasets), indicated that weekly variability in the DMS mixing ratios at Svalbard was highly correlated with variability in the chl‐a concentration in waters in the vicinity of Svalbard (r = 0.89). Hourly‐to‐daily variability in the DMS mixing ratios were satisfactorily explained by changes in the trajectory, altitude, and speed of air masses passing the DMS sources prior to reaching Svalbard. The observed coupling between DMS mixing ratios and chl‐a concentration is surprising, and indicates that the variability in chl‐a concentrations in the study area represents the change in the abundance of phytoplankton capable of producing DMS. The intensive monitoring of DMS levels at Svalbard enabled us to identify in situ production and the flux of oceanic DMS over the Arctic region. It thus constitutes a useful analytical tool for detecting changes in DMS production associated with variations in phytoplankton productivity resulting from changes in sea ice extent as a consequence of Arctic seasonality and warming.

Temporal and spatial variations in phytoplankton productivity in surface waters of a warm-temperate, monomictic lake in New Zealand

Surface phytoplankton productivity measurements were carried out in morphologically complex Lake Rotoiti with the objective of defining variations between sites and seasons, and the dominant environmental drivers of these variations. Measurements were carried out monthly at two depths at each of three morphologically diverse stations for 1 year throughout the lake. Productivity at the surface of the shallow embayment was significantly higher in most months of the year compared with the surface of the other two stations but there were no significant differences from September to December 2004. There were no relationships between measured environmental variables and primary productivity or specific production. Inorganic nutrient concentrations at the surface of the shallow station were low throughout the whole year but at the other two stations they showed a typical pattern for monomictic lakes of higher levels during winter mixing and declining concentrations during thermal stratification. The high variability between sites found in this study indicates that it is important to account for local differences in productivity in morphologically diverse lakes, and that whole lake productivity estimates may vary greatly depending on the location and depth of productivity measurements.

Phytoplankton production in Italian freshwater and marine ecosystems: State of the art and perspectives

The present work aims at evaluating the state of art of phytoplankton production research in Italy. We present a synthesis of the main results achieved in three ecosystems where primary production studies have been carried out most intensively: a large subalpine lake (Lago Maggiore, LM), a shallow marine ecosystem with strong fluvial influence (the Northern Adriatic Sea, NAS), and a coastal area of the Southern Tyrrhenian Sea (the Gulf of Naples, GoN). The present yearly production values are around 150 g C m−2 yr−1 in LM and GoN; this ranges between 80 (offshore) and 150 g C m−2 yr−1 (coast) in the NAS. The temporal and spatial variations of phytoplankton production appeared, in each ecosystem, in accordance with the trophic changes. Significant correlations between production, chlorophyll, and light were generally observed for LM and for GoN. On the contrary, these parameters were poorly correlated in the NAS, hampering the use of predictive models in this ecosystem. Discrepancies between primary production and the actual phytoplankton biomass changes were observed across trophic gradients: the largest part of the carbon that is photosynthetically produced does not seem to be transformed into new phytoplankton biomass, strongly affecting the interpretation of the production figures in the ecosystems.

Biomass, feeding and metabolism of mesozooplankton in the equatorial Pacific along 180°

Abstract Mesozooplankton biomasses, grazing rates, and metabolism (respiration, ammonium and phosphate excretion) were measured in the central Pacific (180°; 8°S–8°N) during the EBENE cruise, in October–November 1996. In the HNLC zone, the highest mesozooplankton biomass occurred between 6°S and the equator. The decrease of biomass at the northern part of the HNLC zone was accounted to the passage of a tropical instability wave, carrying poorer zooplankton concentrations from the north. Within the HNLC zone, most of the biomass (60–96%) was found above 100 m in accordance with the upper distribution of phytoplankton and heterotrophic protists. No significant day–night differences were observed in mesozooplankton biomass. These results suggest a strong and permanent coupling between mesozooplankton and the first links of the food chain. Respiration and phosphate excretion rates were steady at the different latitudes, but at the equator, grazing rates were the lowest, and ammonium excretion the highest. These variations were accounted to latitudinal differences in microzooplankton density and in particles C/N ratios, suggesting that more nitrogen was available for food at the equator. Moreover, among the dominant copepod species, higher proportions of carnivorous were found at the equator. Higher particle grazing and ammonium excretion rates occurred at the equator during the day, while the chlorophyll gut content of copepods did not show any significant diel cycle. These results suggest a strong trophic link between mesozooplankton feeding activity, on the one hand, and cyclic variations of phytoplankton production and of of their main predators (microzooplankton protists), on the other hand. From biomass estimations of phytoplankton and protists in the euphotic layer and results of dilution experiments, the production and grazing mortality of the main autotrophic taxa (from picoplankton to microplankton) were computed at the equator. Mesozooplankton, which was mainly involved in the catch of the largest (>8 μm) food particles, such as diatoms or dinoflagellates, accounted for only a minor part (22%) in total phytoplankton grazing, compared to microzooplankton. As the chlorophyll ration was insufficient to balance its metabolism expenditures, mesozooplankton had to to complete its diet with other sources of food such as microzooplankton. The low level of zooplankton metabolic O:N ratios, suggesting the use of a food with a large protein content, supports of this hypothesis.

Diel cycles in viral infection of bacterioplankton in the North Sea

Diel variations in substrate availability (largely due to variations in phytoplankton production) can lead to pronounced diel patterns in prokaryotic activity in the euphotic zone. We examined short-term changes in viral infection of bacterioplankton and its relation to bacterial activ- ity in 3 distinct masses of North Sea surface waters marked by drifting buoys in June 2001 and April 2002. The water masses were sampled every 4 to 6 h for a period of 20 to 36 h. The frequency of infected cells (FIC) estimated by a virus dilution approach varied from 5 to 64% at the western site, 17 to 55% at the southern site, and 10 to 22% at the northern site and was generally higher during the night than at daytime. Furthermore, FIC was negatively related to bacterial activity at all sites. Bacterial activity, measured via ( 14 C)-leucine incorporation, was ca. 1.5- to 5-fold higher during the day than at night. Our results indicate that viral lysis of bacteria occurs around noon to afternoon, and infection mainly during the night. Moreover, lysis and viral production seem to take place during high bacterial activity; this could be a strategy to increase the number of newly produced viruses.

Seasonal and interannual variations in phytoplankton production at DYFAMED time-series station, northwestern Mediterranean Sea

Abstract Phytoplankton carbon assimilation has been measured near monthly using the 14C method at DYFAMED France JGOFS time-series station from 1993 to 1999. Data were obtained using the “LET GO” technique, which allowed in situ injection of bicarbonate and incubation in enclosures at 10 depths. Incubation duration was 4 h around noon, from which daily production was estimated. The seasonal variation of the depth-integrated carbon assimilation exhibits a marked cycle. Maximum values reach 1.8 g C m−2 d−1 in March or April; constant lower values were observed from August to January, in the range 100–300 mg C m−2 d−1. The annual primary production vary in the range 86–232 g C m−2 yr−1, in the upper range of older estimations. Primary production normalized to chlorophyll a shows maximum values in the period of oligotrophy. This increase of carbon assimilation rate per unit of chlorophyll a appears as linked to the period of phosphorus-limited ecosystem, and vertical distribution of taxonomic pigments suggests a possible role of cyanobacteria. Potential export production has been estimated from primary production data and Fp ratio based on pigments concentrations. These estimates (which imply biological steady state conditions) vary in a wide range, from 19 to 71 g C m−2 yr−1. There is a decoupling between years with high potential export production and years with high measured particulate fluxes, which highlights the question of balance by resupply of the limiting nutrients and the role of dissolved organic carbon. A possible shift of primary production towards a more regeneration-dominated system is suggested for recent years.

Daily Variation in Phytoplankton Production in Two Subestuaries of Waquoit Bay, Massachusetts.

Previous articleNext article No AccessECOLOGY: PHYTOPLANKTON DYNAMICSDaily Variation in Phytoplankton Production in Two Subestuaries of Waquoit Bay, MassachusettsJ. L. Boxhill, L. S. Vázquez, T. R. Harrison, K. Foreman, and J. N. KremerJ. L. Boxhill Search for more articles by this author , L. S. Vázquez Search for more articles by this author , T. R. Harrison Search for more articles by this author , K. Foreman Search for more articles by this author , and J. N. Kremer Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Biological Bulletin Volume 187, Number 2October 1994 Published in association with the Marine Biological Laboratory Article DOIhttps://doi.org/10.1086/BBLv187n2p284 Views: 8Total views on this site Copyright © 1994 by Marine Biological LaboratoryPDF download Crossref reports no articles citing this article.

The Effects of Wind Speed and Direction on Stratification and Phytoplankton Production in an Estuary of Waquoit Bay, Massachusetts.

Previous articleNext article No AccessECOLOGY: PHYTOPLANKTON DYNAMICSThe Effects of Wind Speed and Direction on Stratification and Phytoplankton Production in an Estuary of Waquoit Bay, MassachusettsL. Z. Santiago Vázquez, J. L. Boxhill, T. R. Harrison, J. N. Kremer, and K. ForemanL. Z. Santiago Vázquez Search for more articles by this author , J. L. Boxhill Search for more articles by this author , T. R. Harrison Search for more articles by this author , J. N. Kremer Search for more articles by this author , and K. Foreman Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Biological Bulletin Volume 187, Number 2October 1994 Published in association with the Marine Biological Laboratory Article DOIhttps://doi.org/10.1086/BBLv187n2p285 Views: 22Total views on this site Copyright © 1994 by Marine Biological LaboratoryPDF download Crossref reports no articles citing this article.

Transient variations in phytoplankton productivity at the JGOFS Bermuda time series station

Time series of 13 days in August and 18 days in March–April reveal high variability in phytoplankton productivity on a time scale of days. Specific growth rates were also variable, ranging from 0.1 to 0.7 day −1 in August and from <0.10 to 1.3 day −1 in March–April. Picoplankton accounted for most productivity and biomass in the mean. Pigment markers suggest that Synechococcus and prochlorophytes dominated the picoplankton in the surface layer and the chlorophyll maximum, respectively. Phytoplankton respectively accounted for an average of 7% and 8% of particulate organic matter in the surface mixed layer and bottom layer of the euphotic zone in the August time series, compared to 11% and 21% in the March–April time series. Biomass peaks were associated with increases in prochlorophytes, prymnesiophytes and diatoms during both time series. Passage of Hurricane Dean at the beginning of the August time series had little impact on euphotic zone chlorophyll, but productivity declined by 70%. The subsequent increase in productivity was initiated by an increased growth rate in the mixed layer followed by a nitrate-dependent increase in growth rate in the bottom layer of the euphotic zone. Variations in productivity during the March time series were related to incident radiation and to changes in biomass as different water masses moved through the region. Nitrate flux and productivity were closely coupled during the August time series and uncoupled during the March time series.

Control of marine fish production

In the trophic‐dynamic hypothesis, biomass production was assumed limited by factors that control energy transfer. An analysis using trophic‐dynamic models applied to ocean data, however, leads to a rejection of that hypothesis and supports a hypothesis that carnivorous fish production is controlled by the amount of new N annually incorporated into phytoplankton biomass and transferred through food webs. For an average 2.5 trophic transfers from phytoplankton to fish in environments ranging from oceanic to northeast North American coastal waters, N transfer efficiency was a constant 0.28 while C transfer efficiency increased nonlinearly from 0 to an asymptotic value of 0.16. Fish production was more sensitive to variations in phytoplankton production in oligotrophic than in eutrophic marine environments as a result of a nonlinear decrease in f, the ratio of new to total production, as primary production decreased.

Benthic fluxes in San Francisco Bay

Measurements of benthic fluxes have been made on four occasions between February 1980 and February 1981 at a channel station and a shoal station in South San Francisco Bay, using in situ flux chambers. On each occasion replicate measurements of easily measured substances such as radon, oxygen, ammonia, and silica showed a variability (±1σ) of 30% or more over distances of a few meters to tens of meters, presumably due to spatial heterogeneity in the benthic community. Fluxes of radon were greater at the shoal station than at the channel station because of greater macrofaunal irrigation at the former, but showed little seasonal variability at either station. At both stations fluxes of oxygen, carbon dioxide, ammonia, and silica were largest following the spring bloom. Fluxes measured during different seasons ranged over factors of 2–3, 3, 4–5, and 3–10 (respectively), due to variations in phytoplankton productivity and temperature. Fluxes of oxygen and carbon dioxide were greater at the shoal station than at the channel station because the net phytoplankton productivity is greater there and the organic matter produced must be rapidly incorporated in the sediment column. Fluxes of silica were greater at the shoal station, probably because of the greater irrigation rates there. N + N (nitrate + nitrite) fluxes were variable in magnitude and in sign. Phosphate fluxes were too small to measure accurately. Alkalinity fluxes were similar at the two stations and are attributed primarily to carbonate dissolution at the shoal station and to sulfate reduction at the channel station. The estimated average fluxes into South Bay, based on results from these two stations over the course of a year, are (in mmol m−2d−1):O2= −27 ± 6; TCO2= 23 ± 6; Alkalinity = 9 ± 2; N + N = −0.3 ± 0.5; NH3 = 1.4 ± 0.2; PO4 = 0.1 ± 0.4; Si = 5.6 ± 1.1. These fluxes are comparable in magnitude to those in other temperate estuaries with similar productivity, although the seasonal variability is smaller, probably because the annual temperature range in San Francisco Bay is smaller.

Seasonal Variations of Phytoplankton Production in an Estuary in Relation to Coastal Water Movements

Primary production and phytoplankton biomass in Port Hacking, an estuary 24 km south of Sydney, were measured at 2-4 day intervals for one year. Primary production was measured by in situ 14C uptake, and phytoplankton biomass by 14C uptake at constant irradiance and in vivo chlorophyll fluorescence. Measurements of solar irradiance and light attenuation by the water column were also obtained. Nutrient concentrations were measured both in the estuary and in the coastal waters adjacent to Port Hacking. The short-term variations of phytoplankton biomass were found to be due to both estuarine hydrological events resulting in the release of regenerated nutrients, and to coastal hydrological events, where slope water intrusions enriched the coastal waters and were introduced into the estuarine basins by tidal exchange. The annual variation of primary production in Port Hacking was related to the annual variation of solar irradiance. A minor part of the annual variation appeared to be due to temperature, but the nature of this relationship was uncertain.

Environmental regulation of phytoplankton productivity in the lower Hudson Estuary

Phytoplankton productivity and mean photic zone chlorophyll a concentrations ranged from 0.01 g C m −2 d −1 (December) to 2.22 g C m −2 d −1 (July) and from 0.8 μg Chl l −1 (December) to 6.4 μg Chl l −1 (July), respectively. Dissolved inorganic nutrient concentrations were high throughout the year, and (with the possible exception of silicate during the summer) temporal variations were not correlated with concurrent variations in phytoplankton productivity. Chlorophyll a specific phytoplankton productivity was regulated by light and temperature. Nanoplankton growth accounted for increases in phytoplankton productivity above 0.25 g C m −2 d −1 within the lower Estuary. Except during the summer when phytoplankton growth rates were high, increases in phytoplankton biomass were related to the advection of phytoplankton into the lower Hudson Estuary from Raritan Bay or the Apex of the New York Bight. Although major nutrient concentrations were consistently high, netplankton growth rates were apparently less than flushing rates and, therefore, too low to generate blooms in the lower Estuary.