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Journal ArticleDOI

Predicting marine phytoplankton community size structure from empirical relationships with remotely sensed variables

TL;DR: In this article, the authors describe relationships between the environment and the size composition of phytoplankton communities, using a collation of empirical measurements of size composition from sites that include polar, tropical and upwelling environments.
Abstract: The size composition of primary producers has a potential influence on the length of marine food chains and carbon sinking rates, thus on the proportion of primary production (PP) that is removed from the upper layers and available to higher trophic levels. While total rates of PP are widely reported, it is also necessary to account for the size composition of primary producers when developing food web models that predict consumer biomass and production. Empirical measurement of size composition over large space and time scales is not feasible, so one approach is to predict size composition from environmental variables that are measured and reported on relevant scales. Here, we describe relationships between the environment and the size composition of phytoplankton communities, using a collation of empirical measurements of size composition from sites that include polar, tropical and upwelling environments. The size composition of the phytoplankton communities can be predicted using two remotely sensed variables, chlorophyll-a concentration and sea surface temperature. Applying such relationships in combination allows prediction of the slope and location of phytoplankton size spectra and estimation of the percentage of different sized phytoplankton groups in communities.

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Journal ArticleDOI
TL;DR: In this paper , the authors investigate how individual growth rates, size-structure, relative abundances of species and yields are affected by global warming in a dynamic size spectrum food web model inspired by the offshore Baltic Sea food web.
Abstract: Resolving the combined effect of climate warming and exploitation in a food web context is key for predicting future biomass production, size-structure, and potential yields of marine fishes. Previous studies based on mechanistic size-based food web models have found that bottom-up processes are important drivers of size-structure and fisheries yield in changing climates. However, we know less about the joint effects of ‘bottom-up’ and physiological effects of temperature; how do temperature effects propagate from individual-level physiology through food webs and alter the size-structure of exploited species in a community? Here we assess how a species-resolved size-based food web is affected by warming through both these pathways, and by exploitation. We parameterize a dynamic size spectrum food web model inspired by the offshore Baltic Sea food web, and investigate how individual growth rates, size-structure, relative abundances of species and yields are affected by warming. The magnitude of warming is based on projections by the regional coupled model system RCA4-NEMO and the RCP 8.5 emission scenario, and we evaluate different scenarios of temperature dependence on fish physiology and resource productivity. When accounting for temperature-effects on physiology in addition to on basal productivity, projected size-at-age in 2050 increases on average for all fish species, mainly for young fish, compared to scenarios without warming. In contrast, size-at-age decreases when temperature affects resource dynamics only, and the decline is largest for young fish. Faster growth rates due to warming, however, do not always translate to larger yields, as lower resource carrying capacities with increasing temperature tend to result in declines in the abundance of larger fish and hence spawning stock biomass. These results suggest that to understand how global warming affects the size structure of fish communities, both direct metabolic effects and indirect effects of temperature via basal resources must be accounted for.

13 citations

Journal ArticleDOI
TL;DR: In this paper, the performance of nine PSC models in the coastal Northwest Atlantic (NWA) by comparison of in situ phytoplankton pigment measurements with coincidental satellite data from the Sea-Viewing Wide Field-of-View Sensor (SeaWiFS), Moderate-resolution Imaging Spectroradiometer (MODIS), and the Visible Infrared Imaging Radiometer Suite (VIIRS) was evaluated.
Abstract: Phytoplankton community structure and phytoplankton size class (PSC) are linked to ecological and biogeochemical changes in the oceanic environment. Many models developed to obtain the fraction of PSCs from satellite remote sensing have only been evaluated in open oceans, and very limited effort has been carried out to report on the performance of these PSC models in productive continental shelf waters. In this study, we evaluated the performance of nine PSC models in the coastal Northwest Atlantic (NWA) by comparison of in situ phytoplankton pigment measurements with coincidental satellite data from the Sea-Viewing Wide Field-of-View Sensor (SeaWiFS), Moderate-resolution Imaging Spectroradiometer (MODIS), and the Visible Infrared Imaging Radiometer Suite (VIIRS). Our results show that no PSC model retrieved all three phytoplankton size classes (pico-, nano-, and micro-phytoplankton) with reliable accuracy in the region of interest. In particular, these PSC models showed poor performance for retrieval of the picophytoplankton fraction of total phytoplankton in our study region, which could be related to the under-representation of pico-dominated samples in the productive waters of the NWA. For the accuracy of retrieved microphytoplankton and combined nano–pico phytoplankton fraction, the regional model developed by Devred et al. (2011) yielded the best result, followed by the model of Brewin et al. (2011). The model of Devred et al. (2011) was applied to satellite-derived chlorophyll-a concentration from the Ocean Color Climate Change Initiative (OC-CCI) archive in the NWA from 1998 to 2016. We report solely on the microphytoplankton biomass and fraction given the inverse relationship that exists with the nano–pico class. The multi-decadal trend along with the deseasonalized trend of microphytoplankton fraction was computed and analyzed for six biogeochemical provinces located in the NWA. Over the 19-year time series, there were significant, positive trends for four of the six provinces, with a slope of 0.36%·yr−1 in the Northwest Continental Shelf (NWCS), 0.25%·yr−1 in the Arctic Waters (ARCT), 0.12%·yr−1 in the Slope Waters (SW) and 0.06%·yr−1 in the Gulf Stream (GFST). Strong positive anomalies of microphytoplankton fraction were found in winter months in NWCS between 2009 and 2014, which could be associated with changes in environmental factors.

13 citations

Journal ArticleDOI
TL;DR: In this paper, the essential indicator variables required for the sustained provision of frequently updated integrated ecosystem assessments (IEAs) are identified, and an approach to establishing a global network of coastal observations within the framework of the Global Ocean Observing System.
Abstract: Ecosystem-based approaches (EBAs) to managing anthropogenic pressures on ecosystems, adapting to changes in ecosystem states (indicators of ecosystem health), and mitigating the impacts of state changes on ecosystem services are needed for sustainable development. EBAs are informed by integrated ecosystem assessments (IEAs) that must be compiled and updated frequently for EBAs to be effective. Frequently updated IEAs depend on the sustained provision of data and information on pressures, state changes, and impacts of state changes on services. Nowhere is this truer than in the coastal zone, where people and ecosystem services are concentrated and where anthropogenic pressures converge. This study identifies the essential indicator variables required for the sustained provision of frequently updated IEAs, and offers an approach to establishing a global network of coastal observations within the framework of the Global Ocean Observing System. The need for and challenges of capacity-building are highlighted, and examples are given of current programmes that could contribute to the implementation of a coastal ocean observing system of systems on a global scale. This illustrates the need for new approaches to ocean governance that can achieve coordinated integration of existing programmes and technologies as a first step towards this goal.

12 citations

Posted ContentDOI
TL;DR: In this article, it was shown that small cells play a critical role in the uptake of atmospheric carbon dioxide by the ocean, and are comprised of a spectrum of cell sizes that are strongly associated with different oceanographic conditions.
Abstract: . Phytoplankton plays a critical role in the uptake of atmospheric carbon dioxide by the ocean, and is comprised of a spectrum of cell sizes that are strongly associated with different oceanographic conditions. Studies suggest that the ocean will become increasingly stratified in response to a warming climate, limiting nutrient exchange to the upper sunlit ocean and favouring small cells able to grow in warmer, nutrient poor conditions. Here we show that, in a temperate shelf sea, a summertime population of numerically abundant small cells accounts for approximately 20% of annual carbon uptake. These small cells are not well represented by chlorophyll a – the ubiquitously used proxy of phytoplankton biomass – but rather, are strongly correlated with surface water temperature. Given the persistent near-zero nutrient concentrations during the summer, it appears that small cells drive carbon overconsumption, and suggest that their role in carbon fixation will become increasingly important in a warming ocean.

12 citations


Cites background from "Predicting marine phytoplankton com..."

  • ...Longer food chains, and therefore decreased energy transfer efficiency to higher trophic levels, are associated with assemblages dominated by small cells (Barnes et al., 2011), and a relationship between fish production and nutrient-controlled cell size has been suggested (Sommer et al.,5 2002)....

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Journal ArticleDOI
TL;DR: This study proposes a redefinition of phytoplankton size classification expressed in terms of cell volume metrics, revealing taxonomic group differentiations in nano-micro-macro size classes, thus providing an accurate size classification within and among taxa.
Abstract: To date, p hytoplankton cell size classification is based on linear metrics (nano: 2-20 μm; micro: 20-200 μm; macro: >200 μm) although three-dimensional metrics are used for cell or body size descriptions of all terrestrial and aquatic organisms. This study proposes a redefinition of phytoplankton size classification expressed in terms of cell volume (μm 3 ) metrics by analyzing statistically a data set of 397 species from three major groups of eukaryotic taxa (diatoms, dinoflagellates, coccolithophores). The three size classes based on cell volume metrics are nanoplankton (10-10 3 μm 3 ), microplankton (10 3 -10 6 μm 3 ) and macroplankton (10 6 -10 9 μm 3 ). Size spectra of cell volume frequencies, species richness-cell size and cell abundance-cell size relationships were evaluated with the use of cell volume (μm 3 ) metrics while fitting of the relevant equations significantly accounted for the data. The analysis of size classes versus taxonomic composition based on cell volume metrics revealed taxonomic group (diatoms, dinoflagellates, coccolithophores) differentiations in nano-micro-macro size classes, thus providing an accurate size classification within and among taxa. This classification offers more precise information on the taxon-size relationships, which are valuable for phytoplankton community structure studies and useful for further development of the remote sensing models designed for differentiating phytoplankton taxa by satellite. Normal 0 false false false EL X-NONE X-NONE

11 citations


Cites background from "Predicting marine phytoplankton com..."

  • ...ables, namely, chlorophyll-a concentration and sea surface temperature (Nair et al., 2008; Barnes et al., 2011; Brewin et al., 2011)....

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References
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Journal ArticleDOI
TL;DR: If the organisms are randomly distributed, a single count is sufficient to obtain an estimate of their abundance and confidence limits for this estimate, even if pipetting, dilution or concentration are involved.
Abstract: Various methods for the estimation of populations of algae and other small freshwater organisms are described. A method of counting is described in detail. It is basically that of Utermohl and uses an inverted microscope. If the organisms are randomly distributed, a single count is sufficient to obtain an estimate of their abundance and confidence limits for this estimate, even if pipetting, dilution or concentration are involved. The errors in the actual counting and in converting colony counts to cell numbers are considered and found to be small relative to the random sampling error. Data are also given for a variant of Utermohl's method using a normal microscope and for a method of using a haemocytometer for the larger plankton algae.

2,572 citations


"Predicting marine phytoplankton com..." refers background or methods in this paper

  • ...Sub-samples (100 ml) were settled (Utermıhl technique (Lund et al. 1958)) and individuals counted at the species level with an inverted microscope....

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  • ...technique (Lund et al. 1958)) and individuals counted at the species level with an inverted...

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Journal ArticleDOI
TL;DR: Cellular carbon and nitrogen content and cell volume of nutritionally and morphologically diverse dinoflagellate species were measured to determine carbon to volume and nitrogen to volume relationships.
Abstract: Cellular carbon and nitrogen content and cell volume of nutritionally and morphologically diverse dinoflagellate species were measured to determine carbon to volume (C : vol) and nitrogen to volume (N : vol) relationships. Cellular C and N content ranged from 48 to 3.0 3 10 4 pgC cell 21 21 5

2,137 citations


"Predicting marine phytoplankton com..." refers background in this paper

  • ...0 −− = µvolumeyearCpg Equation 5 reported for taxonomically diverse protist plankton (Menden-Deuer and Lessard 2000)....

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  • ...reported for taxonomically diverse protist plankton (Menden-Deuer and Lessard 2000)....

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Journal ArticleDOI
TL;DR: In this paper, an estimate of global net primary production in the ocean has been computed from the monthly mean near-surface chlorophyll fields for 1979-1986 obtained by the Nimbus 7 CZCS radiometer.
Abstract: An estimate of global net primary production in the ocean has been computed from the monthly mean near-surface chlorophyll fields for 1979-1986 obtained by the Nimbus 7 CZCS radiometer. Our model required information about the subsurface distribution of chlorophyll, the parameters of the photosynthesis-light relationship, the sun angle and cloudiness. The computations were partitioned among 57 biogeochemical provinces that were specified from regional oceanography and by examination of the chlorophyll fields. Making different assumptions about the overestimation of chlorophyll by the CZCS in turbid coastal areas, the global net primary production from phytoplankton is given as 45-50 Gt C year"1. This may be compared with current published estimates for land plants of 45-68 Gt C year"' and for coastal vegetation of 1.9 Gt C year"1.

1,381 citations


"Predicting marine phytoplankton com..." refers background or methods in this paper

  • ...All changes from the implementation of Longhurst et al. (Longhurst et al. 1995) are detailed in Mélin (Mélin 2003)....

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  • ...ocean area (Longhurst et al. 1995), and to regional differences in phytoplankton community...

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  • ...PP was computed from a wavelength- and depthresolved model (Mélin 2003), building on the approach of Longhurst et al. (Longhurst et al. 1995)....

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  • ...This is due to variations in absolute productivity among regions, with 50% of production estimated to come from 27% of ocean area (Longhurst et al. 1995), and to regional differences in phytoplankton community structure....

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  • ...(Longhurst et al. 1995) are detailed in Mélin (Mélin 2003)....

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Journal ArticleDOI
TL;DR: This study provides evidence that reduced body size is the third universal ecological response to global warming in aquatic systems besides the shift of species ranges toward higher altitudes and latitudes and the seasonal shifts in life cycle events.
Abstract: Understanding the ecological impacts of climate change is a crucial challenge of the twenty-first century. There is a clear lack of general rules regarding the impacts of global warming on biota. Here, we present a metaanalysis of the effect of climate change on body size of ectothermic aquatic organisms (bacteria, phyto- and zooplankton, and fish) from the community to the individual level. Using long-term surveys, experimental data and published results, we show a significant increase in the proportion of small-sized species and young age classes and a decrease in size-at-age. These results are in accordance with the ecological rules dealing with the temperature–size relationships (i.e., Bergmann's rule, James' rule and Temperature–Size Rule). Our study provides evidence that reduced body size is the third universal ecological response to global warming in aquatic systems besides the shift of species ranges toward higher altitudes and latitudes and the seasonal shifts in life cycle events.

1,292 citations


"Predicting marine phytoplankton com..." refers background in this paper

  • ...There is evidence that reduced body size is the third universal ecological response to global warming besides the shift of species ranges toward higher altitudes and latitudes and the seasonal shifts in life-cycle events (Daufresne et al. 2009)....

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  • ...higher altitudes and latitudes and the seasonal shifts in life-cycle events (Daufresne et al. 2009)....

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Journal ArticleDOI
TL;DR: In this paper, the frequency distributions of particIe size between sizes of about I and 100 p are given for both surface and deep water of the Atlantic and Pacific Oceans.
Abstract: Frequency distributions of particIe size between sizes of about I and 100 p are given for both surface and deep water of the Atlantic and Pacific Oceans. The form of the size spectra varies predictably both geographically and with depth. A hypothesis is presented to show that, to a first approximation, roughly equal concentrations of material occur at all particle sizes within the range from 1 p to about 10” p, i.e. from bacteria to whales.

1,116 citations