Estimates Of Annual Primary Production Research Articles

Leads in Arctic pack ice enable early phytoplankton blooms below snow-covered sea ice

The Arctic icescape is rapidly transforming from a thicker multiyear ice cover to a thinner and largely seasonal first-year ice cover with significant consequences for Arctic primary production. One critical challenge is to understand how productivity will change within the next decades. Recent studies have reported extensive phytoplankton blooms beneath ponded sea ice during summer, indicating that satellite-based Arctic annual primary production estimates may be significantly underestimated. Here we present a unique time-series of a phytoplankton spring bloom observed beneath snow-covered Arctic pack ice. The bloom, dominated by the haptophyte algae Phaeocystis pouchetii, caused near depletion of the surface nitrate inventory and a decline in dissolved inorganic carbon by 16 ± 6 g C m−2. Ocean circulation characteristics in the area indicated that the bloom developed in situ despite the snow-covered sea ice. Leads in the dynamic ice cover provided added sunlight necessary to initiate and sustain the bloom. Phytoplankton blooms beneath snow-covered ice might become more common and widespread in the future Arctic Ocean with frequent lead formation due to thinner and more dynamic sea ice despite projected increases in high-Arctic snowfall. This could alter productivity, marine food webs and carbon sequestration in the Arctic Ocean.

Modeling spatial patterns of limits to production of deposit-feeders and ectothermic predators in the northern Bering Sea

Network models can help generate testable predictions and more accurate projections of food web responses to environmental change. Such models depend on predator–prey interactions throughout the network. When a predator currently consumes all of its prey's production, the prey's biomass may change substantially with loss of the predator or invasion by others. Conversely, if production of deposit-feeding prey is limited by organic matter inputs, system response may be predictable from models of primary production. For sea floor communities of shallow Arctic seas, increased temperature could lead to invasion or loss of predators, while reduced sea ice or change in wind-driven currents could alter organic matter inputs. Based on field data and models for three different sectors of the northern Bering Sea, we found a number of cases where all of a prey's production was consumed but the taxa involved varied among sectors. These differences appeared not to result from numerical responses of predators to abundance of preferred prey. Rather, they appeared driven by stochastic variations in relative biomass among taxa, due largely to abiotic conditions that affect colonization and early post-larval survival. Oscillatory tendencies of top-down versus bottom-up interactions may augment these variations. Required inputs of settling microalgae exceeded existing estimates of annual primary production by 50%; thus, assessing limits to bottom-up control depends on better corrections of satellite estimates to account for production throughout the water column. Our results suggest that in this Arctic system, stochastic abiotic conditions outweigh deterministic species interactions in food web responses to a varying environment.

Phytoplankton blooms beneath the sea ice in the Chukchi sea

In the Arctic Ocean, phytoplankton blooms on continental shelves are often limited by light availability, and are therefore thought to be restricted to waters free of sea ice. During July 2011 in the Chukchi Sea, a large phytoplankton bloom was observed beneath fully consolidated pack ice and extended from the ice edge to >100km into the pack. The bloom was composed primarily of diatoms, with biomass reaching 1291mg chlorophyll am−2 and rates of carbon fixation as high as 3.7gCm−2d−1. Although the sea ice where the bloom was observed was near 100% concentration and 0.8–1.2m thick, 30–40% of its surface was covered by melt ponds that transmitted 4-fold more light than adjacent areas of bare ice, providing sufficient light for phytoplankton to bloom. Phytoplankton growth rates associated with the under-ice bloom averaged 0.9d−1 and were as high as 1.6d−1. We argue that a thinning sea ice cover with more numerous melt ponds over the past decade has enhanced light penetration through the sea ice into the upper water column, favoring the development of these blooms. These observations, coupled with additional biogeochemical evidence, suggest that phytoplankton blooms are currently widespread on nutrient-rich Arctic continental shelves and that satellite-based estimates of annual primary production in waters where under-ice blooms develop are ~10-fold too low. These massive phytoplankton blooms represent a marked shift in our understanding of Arctic marine ecosystems.

Vertical variability of primary production and chlorophyll a in the Drake Passage during the austral spring period (October–November)

Vertical distribution of primary production (PP) and concentration of chlorophyll a (Chl) were studied during two cruises in the Drake Passage in November 2007 and 2008. Variability in the vertical curves of Chl was registered in the different hydrological zones of the Drake Passage. The Antarctic waters were characterized by a well-defined deep Chl maximum (DCM) during the austral spring. The investigation allowed us to conclude that the influence of DCM should be taken into consideration for a model-based estimation of annual PP in the Southern Ocean.

Typhoon-driven variations in primary production and phytoplankton assemblages in Sagami Bay, Japan: A case study of typhoon Mawar (T0511)

Climate change has the potential for intensification of typhoons, which will cause stronger effects on aquatic ecosystems in the future. The effect of typhoon Mawar (T0511), passing Manazuru Port located in the western part of Sagami Bay, Japan, was investigated from August to September 2005. Immediately after the passage of Mawar, photosynthetically available radiation showed high values, salinity decreased dramatically and nutrient concentrations (NO2+NO3, PO4 and Si(OH)4) increased. Skeletonema spp. and Leptocylindrus spp. were dominant after the passage of Mawar, and their succession was linked to the variability of the N/P ratio. Primary production was highest at 349 mg C m−3 day−1 three days after Mawar, and high assimilation numbers lasted for nine days. The integrated primary production during the nine days after Mawar was 2.1×103 mg C m−3, which accounted for 7.2–9.1% of the annual primary production in the upper waters of Sagami Bay. The study confirms that enhanced primary production induced by episodic typhoon events in temperate coastal regions are significant, and should be considered in annual primary production estimates.

Phytoplankton production and growth rate in Lake Tanganyika: evidence of a decline in primary productivity in recent decades

Summary1. This study focused on phytoplankton production in Lake Tanganyika. We provide new estimates of daily and annual primary production, as well as growth rates of phytoplankton, and we compare them with values published in former studies.2. Chlorophyll‐a(chl‐a) in the mixed layer ranged from 5 to 120 mg chl‐a m−2and varied significantly between rainy and dry seasons. Particulate organic carbon concentrations were significantly higher in the south basin (with 196 and 166 mg C m−3in the dry and the rainy season, respectively) than in the north basin (112 and 109 mg C m−3, respectively).3. Carbon : phosphorus (C : P) ratios varied according to season. Phosphorus limitation seemed to occur more frequently than nitrogen limitation, especially during the rainy season. Severe P deficiencies were rare.4. Measured particulate daily primary production ranged from 110 to 1410 mg C m−2 day−1; seasonal contrasts were well marked in the north basin, but less in the south basin, where primary production peaks occurred also in the rainy season. Estimates of annual primary production, based on daily primary production calculated from chl‐aand water transparency, gave values lower than those reported in previous studies. Picophytoplankton accounted on average for 56% of total particulate production in the south basin during the wet season of 2003.5. Phytoplankton growth rates, calculated from primary production, ranged from 0.055 to 0.282 day−1; these are lower than previously published values for Lake Tanganyika.

Modeling coccolithophores in the global oceans

Abstract Coccolithophores are important ecological and geochemical components of the global oceans. A global three-dimensional model was used to simulate their distributions in a multi-phytoplankton context. The realism of the simulation was supported by comparisons of model surface nutrients and total chlorophyll with in situ and satellite observations. Nitrate, silica, and dissolved iron surface distributions were positively correlated with in situ data across major oceanographic basins. Global annual departures were +18.9% for nitrate (model high), +5.4% for silica, and +45.0% for iron. Total surface chlorophyll was also positively correlated with satellite and in situ data sets across major basins. Global annual departures were −8.0% with Sea-viewing Wide Field-of-view Sensor (SeaWiFS) (model low), +1.1% with Aqua, and −17.1% with in situ data. Global annual primary production estimates were within 1% and 9% of estimates derived from SeaWiFS and Aqua, respectively, using a common primary production algorithm. Coccolithophore annual mean relative abundances were 2.6% lower than observations, but were positively correlated across basins. Two of the other three phytoplankton groups, diatoms and cyanobacteria, were also positively correlated with observations. Distributions of coccolithophores were dependent upon interactions and competition with the other phytoplankton groups. In this model, coccolithophores had a competitive advantage over diatoms and chlorophytes by virtue of a greater ability to utilize nutrients and light at low values. However, their higher sinking rates placed them at a disadvantage when nutrients and light were plentiful. In very low nutrient conditions, such as the mid-ocean gyres, coccolithophores were unable to compete with the efficient nutrient utilization capability and low sinking rate of cyanobacteria. Comparisons of simulated coccolithophore distributions with satellite-derived estimates of calcite concentration and coccolithophore blooms showed some agreement, but also areas of departure. Vast blooms observed in the North Atlantic were well-represented by the model. However, model coccolithophores were nearly absent in the North Pacific, while calcite estimates suggested widespread abundance in summer. In situ observations supported the satellite calcite, suggesting a deficiency in the model. New satellite estimates of phytoplankton groups indicated good agreement of diatoms in one case, and poor agreement in general in another. Comparisons of phytoplankton group primary production with other models showed wide disparity. The divergence among models and satellite estimates is common for such an emerging field of research. The quantitative comparisons with in situ observations are encouraging, but disparities with model and satellite estimates suggested that further research is needed.

Assimilation of SeaWiFS ocean chlorophyll data into a three-dimensional global ocean model

Sea-viewing Wide Field-of-view Sensor (SeaWiFS) chlorophyll data were assimilated with an established three-dimensional global ocean model. The assimilation improved estimates of chlorophyll relative to a free-run (no assimilation) model. Compared to SeaWiFS, annual bias of the assimilation model was 5.5%, with an uncertainty of 10.1%. The free-run model had a bias of 21.0% and an uncertainty of 65.3%. In situ data were compared to the assimilation model over a 6-year time period from 1998 through 2003, indicating a bias of 0.1%, and an uncertainty of 33.4% for daily coincident, co-located data. SeaWiFS bias was slightly higher at − 1.3% and nearly identical uncertainty at 32.7%. The free-run bias and uncertainty at − 1.4% and 61.8%, respectively, indicated how much the assimilation improved model results. Annual primary production estimates for the 1998–2003 period produced a nearly 50% improvement by the assimilation model over the free-run model as compared to a widely used algorithm using SeaWiFS chlorophyll data. These results suggest the potential of assimilation of satellite ocean chlorophyll data for improving model results.

PRIMARY PRODUCTION REQUIRED TO SUPPORT BOTTLENOSE DOLPHINS IN A SALT MARSH ESTUARINE CREEK SYSTEM

AbstractWe developed a model to estimate the proportion of annual primary production required to support bottlenose dolphins within the 32‐km2 North Inlet salt marsh creek system in South Carolina, U. S. A. The estimated annual prey consumption by dolphins was compared to the total annual production of prey available to dolphins, as determined from estimates of annual primary production, trophic transfer efficiencies, and the mean trophic level of prey. A best estimate range of 3.2%‐6.8% of the total annual primary production of the North Inlet system was required to support an average population of only six dolphins (maximum range of 0.4%–7.0%). Dolphins were estimated to consume 11.1–14.2 metric tons of fish (wet weight) each year in North Inlet. The proportion of North Inlet primary production required to support dolphins increased dramatically during the winter months, when primary production declined but dolphin numbers remained similar. This period was marked by a decline in the abundance of available prey species and by a shift in the creek utilization patterns of dolphins. Despite the numerical scarcity of dolphins in the system, they appear to have a significant ecological impact and may be important predators of overwintering prey species.

Abundance, biomass and composition of the sea ice biota of the Greenland Sea pack ice

During two cruises to the Greenland Sea, we studied the abundance and biomass of the sea ice biota in summer and late autumn. The mean calculated biomass of the sympagic community was 0.2 g C m −2 ice. Algae contributed on average 43% to total biomass, followed by bacteria (31%), heterotrophic flagellates (20%), and meiofauna (4%). Diatoms were the main primary producers (60% of total algal biomass), but flagellated cells contributed significantly to the algal biomass. Among the meiofauna, ciliates, nematodes, acoel turbellarians and crustaceans were dominant. Calculated potential ingestion rates of meiofauna (0.6 g C m −2 (120 d) −1) are on the same order of magnitude as annual primary production estimates for Arctic multi-year sea ice. We therefore assume that grazing can control biomass accumulation of primary producers inside the sea ice.

Estimation of annual primary production in the Kuroshio waters northeast of Taiwan using a photosynthesis-irradiance model

Photosynthesis-irradiance ( P B – E ̄ ) relationships for Kuroshio waters at different depths in different seasons were established using repeated measurements of primary productivity at a station northeast of Taiwan. The P B – E ̄ approach is different from the conventional P B– E approach in that a much longer incubation time is required to measure primary productivity. By plotting the daytime averaged, chlorophyll specific primary productivity ( P B ) against the daytime averaged irradiance ( E ̄ ) , the optimal rate of photosynthesis ( P B opt) in the mixed layer was found to be 5.87 mgC [mgChl a] -1 h -1 in summer and 2.88 mgC [mgChl a] -1 h -1 in winter. The initial slope of the P B – E ̄ curve, however, remained around 0.01 mgC [mgChl a] -1 h -1 [μEinstein m -2 s -1] -1 throughout the year. Below the mixed layer, the P B opt decreased substantially to less than half of that within the mixed layer. A similar decrease was also observed in the initial slope. The euphotic zone integrated primary production as calculated from these P B – E ̄ parameters was close to that measured in situ, with relative error less than 6%. Based on the measured P B – E ̄ parameters, it was estimated here that the annual primary production was 104 gC m -2 yr -1 (285 mgC m -2 d -1). The established P B – E ̄ relationships may serve as a better regional algorithm in the assessment of primary production for Kuroshio waters.

Primary production in Southern Ocean waters

The Southern Ocean forms a link between major ocean basins, is the site of deep and intermediate water ventilation, and is one of the few areas where macronutrients are underutilized by phytoplankton. Paradoxically, prior estimates of annual primary production are insufficient to support the Antarctic food web. Here we present results from a primary production algorithm based upon monthly climatological phytoplankton pigment concentrations from the coastal zone color scanner (CZCS). Phytoplankton production was forced using monthly temperature profiles and a radiative transfer model that computed changes in photosynthetically usable radiation at each CZCS pixel location. Average daily productivity (g C m−2 d−1) and total monthly production (Tg C month−1) were calculated for each of five geographic sectors (defined by longitude) and three ecological provinces (defined by sea ice coverage and bathymetry as the pelagic province, the marginal ice zone, and the shelf). Annual primary production in the Southern Ocean (south of 50°S) was calculated to be 4414 Tg C yr−1, 4–5 times higher than previous estimates made from in situ data. Primary production was greatest in the month of December (816 Tg C month−1) and in the pelagic province (contributing 88.6% of the annual primary production). Because of their small size the marginal ice zone (MIZ) and the shelf contributed only 9.5% and 1.8%, respectively, despite exhibiting higher daily production rates. The Ross Sea was the most productive region, accounting for 28% of annual production. The fourfold increase in the estimate of primary production for the Southern Ocean likely makes the notion of an “Antarctic paradox” (primary production insufficient to support the populations of Southern Ocean grazers, including krill, copepods, microzooplankton, etc.) obsolete.

Particle flux in deep seas: regional characteristics and temporal variability

Particle flux data have been collated from the literature representing most areas of the open ocean to determine regional trends in deep water flux and its seasonal variability. Organic carbon flux data normalised to a depth of 2000 m exhibits a range of an order of magnitude in areas outside the polar domains (0.38 to 4.2 g/m2/y). In polar regions the range is wider (0.01–5.9 g/m2/y). Latitudinal trends are not apparent for most components of the flux although calcite flux exhibits a poleward decrease. Limited data from polar regions show fluxes of opaline silica not significantly higher than elsewhere.The variability of flux over annual cycles was calculated and expressed as a Flux Stability Index (FSI) and the relationship between this and vertical flux of material examined. Somewhat surprisingly there is no significant relationship between FSI and fluxes of dry mass, organic carbon, inorganic carbon or opaline silica. At each site, net annual primary production was determined using published satellite derived estimates. There is a negative but weak relationship between FSI and the proportion of primary production exported to 2000 m (e2000 ratio). The most variable of the non-polar environments export to 2000 m about twice as much of the primary production as the most stable ones. Polar environments have very low e2000 ratios with no apparent relationship to FSI.At primary production levels below 200 g C/m2/y there is a positive correlation between production and organic carbon flux at 2000 m but above this level, flux remains constant at about 3.5g C/m2/y. A curve derived to describe this relationship was applied to estimates of annual primary production in each of 34 of the open ocean biogeochemical provinces proposed by Longhurst et al. (1995). Globally, open ocean flux of organic carbon at 2000 m is 0.34 Gt/yr which is 1% of the total net primary production in these regions. This flux is nearly equally divided between the Atlantic, Pacific and Southern Oceans. The Indian and Arctic oceans between them only contribute 5% to the total.The eight planktonic climatological categories proposed by Longhurst (1995) provide a most useful means of examining the data on flux and its variability. A characteristic level of FSI was found in each category with highest levels in the tropics and lowest levels in the Antarctic. There is also a characteristic level of export ratio in each category with the highest in monsoonal environments (1.7%) and the lowest in Antarctica (0.1%).

The effect of temporal undersampling on primary production estimates

Annual primary production estimates for specific oceanic regions have typically been made using a variety of measures of productivity spaced, at best, several weeks apart Primary productivity in the oceans is known to be extremely episodic. It is hypothesized here that primary production data with a temporal resolution of several weeks have a high potential for error due to undersampling. In the present analysis, time series of gross primary productivity were calculated using time series of photosynthetically available radiation and chlorophyll a concentration as input to an optical production model. The input data are of minute scale resolution and were gathered during a number of moored experiments. These took place over the past 5 years at several oceanic sites. The minute scale productivity time series were integrated to form time series of daily estimates of gross production. These range in duration from 40 to 260 days. The time series exhibit several regimes characteristic of oceanic primary productivity, such as phytoplankton blooms, productivity pulses associated with advected water masses, steady state growth, and development of a subsurface productivity maximum. The presence of these features makes our time series ideal for investigating (1) the sensitivity of annual production estimates to the timing of the sample set and (2) the error introduced by undersampling inherent in coarser sampling methods. It was found that distinct pulses of productivity generate the greatest error and that high variability leads to large errors, even for well‐resolved sampling intervals. The maximum percent error due to undersampling was found to be 85%. Additionally, up to a fourfold range between the maximum and minimum estimates of average daily production was found over all sampling intervals. Finally, the maximum expected range (300 g C m−2 yr1) and the expected standard deviation (±42 g C m−2 yr1) for annual water column production were determined at a Sargasso Sea site for which long‐term productivity time series were available at four depths within the euphotic zone.

Monsoonal differences in primary production in the eastern Banda Sea (Indonesia)

14C incorporation into phytoplankton of the eastern Banda Sea was registered during incubations of samples, both in situ and in an incubator equipped with blue filters. Light conditions throughout the euphotic zone were apparently simulated quite well in the deck incubator: the agreement between the two series of measurements was very good. Primary production was 1.85 g C·m −2..d t-1 in August 1984, after upwelling forced by the southeast monsoon; values ranged from 0.5 g C·m −2..d t-1 in the open Banda Sea up to 7 g C·m −2..d t-1 south of Irian Jaya. In February 1985, when the upper part of the water column was stratified due to persistent monsoonal winds from the northwest, primary production was less: 0.91 g C·m −2..d t-1. In August 1984 production was also measured with the oxygen method. The photosynthetic quotient was 1.05 near the surface and up to 1.86 near the bottom of the euphotic zone. Extrapolation of all measurements to an estimate of annual primary production resulted in a value as high as 5·10 2 g C·m −2..d t-1. The assimilation ratio in surface samples was locally up to 8 mg C·(mg chl. a) −1.h −1 (in the photoperiod) during both cruises, with a mean of 5.85 in August 1984 and 5.95 in February 1985. The surprisingly high values during the oligotrophic conditions of February underline the importance of rapid recycling of nutrients in the euphotic zone.

The Estimation of Annual Primary Production in a High Energy Surf-Zone

The Estimation of Annual Primary Production in a High Energy Surf-Zone

BIOMASA Y PRODUCCION PRIMARIA DE CHUSQUEA CULEOU DESV. Y CHUSQUEA TENUIFLORA PHIL. EN EL SUR DE CHILE

The productivity of stands of C. culeou and C. tenuiflora wa s studied developing a methodological basis for future ecological studies of Chusquea spp. The phenology of the two species and the habitat condition of study sites are described. The standing above ground biomass for C. culeou wa s estimated as 156-162 t ha-1 and represented that of the whol e community since no other species wer e present in significant quantities. For. C. tenuiflora the standing biomass of 13.0 t ha-1 account for most of the biomass of the understorey but only for a small fraction on the total standing biomass of the mixed Nothofagus forest under which it grows. Th e annual dry matter production in the C. culeou thicket determined as the sum of annual leaf fall (4.27 t ha - 1 ) and the biomass of one year old culms ammounted to 10-11.4 t ha-1 . The magnitude of the net primary production of C. tenuiflora is suggested by the 1.0 t ha-1 of new culm growt h per year. Th e above ground biomass of 156-162 t ha-1 estimated for the C. culeou thicket is greater than the values reported for many forests and the estimation of annual primary production 10- 11.4 t ha - 1 ) for the C. culeou stand lies between the average values reported for boreal forests and temperature forests.

Primary Production in the Chesapeake Bay

Estimates of annual primary production and standing crops based on chlorophylla were made in the northern half of Chesapeake Bay over a 160 km section. Both the chlorophylla concentrations and incubator productivity were maximum during the warmer season, especially in the oligohaline area. The higher salinity waters usually showed lower values of both parameters, except during the winter when values were fairly uniform over the entire study area. Chlorophylla values ranged from 1 to 80 mg m−3 up-bay at Station I-B, and 1 to 25 mg m−3 down-bay at Station XI. Incubator photosynthesis ranged from 2 to 200 mg C m−3 hr−1 up-bay and 2 to 40 mg C m−3 hr−1 down-bay. Chlorophylla concentrations and incubator productivity were usually low at the tidal freshwater station, rapidly increased in the oligohaline area and tended to decrease with increasing salinity. The seasonal pattern was characterized by one general maximum during the warm months with little tendency for a spring bloom and, occasionally, some stations showed a late fall pulse in standing crop and photosynthesis. Photosynthetic activity per unit chlorophylla at the down-bay stations ranged from 1.3 to 10.3 mg C hr−1 mg Chla −1 and the seasonal average was 3.9. The assimilation numbers at the up-bay stations ranged from <1 to 11.9 mg C hr−1 (mg Chla −1 and averaged 3.3 and 1.1 during the warm and cold periods, respectively. Computed values of integral gross photosynthesis averaged about 0.2 g C m−2 day−1 at the up-bay stations and approximately 1.0 g C m−2 day−1 at the down-bay stations over the period of November, 1966 to October, 1967. Turbidity of the waters appeared to have a controlling influence on primary production in the water column. However, photosynthetic activity was highest in turbid up-bay water on a volume basis.