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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01 Jan 2014
TL;DR: In this article, a theoretical framework for predicting the effects of temperature on competition among species, based on understanding the effects on the physiological and population parameters of the species, is presented, which helps unify formal resource competition theory with metabolic and physiological ecology.
Abstract: Summary 1. Temperature is a key driver of ecological processes and patterns. The ramifications of temperature for ecological communities include not only its direct effects on the physiology of individuals, but also how these effects play out in the context of other processes such as competition. 2. Apparently idiosyncratic or difficult to predict effects of temperature on competitive outcomes are well represented in the literature. General theoretical understanding of how physiological influences of temperature filter through community dynamics to determine outcomes is limited. 3. We present a theoretical framework for predicting the effects of temperature on competition among species, based on understanding the effects of temperature on the physiological and population parameters of the species. The approach helps unify formal resource competition theory with metabolic and physiological ecology. 4. Phytoplankton and many other ectotherms are smaller at higher temperatures. This has been observed experimentally, across geographical gradients, and as change accompanying climate warming, but it has not been explained in terms of competition. As a case study, we apply our theoretical framework to competition for nutrients among differently sized phytoplankton. 5. Based on this analysis, we hypothesize that the prevalence of smaller phytoplankton at higher temperatures is at least partly due to an accentuated competitive advantage of smaller cells at higher temperatures with respect to nutrient uptake and growth. We examine the scope for extending the approach to understand resource competition, generally, among ectotherms of different sizes.
6 citations
Dissertation•
01 Sep 2012
TL;DR: In this paper, a multispecies size-spectrum model was developed to explore the dynamics of the pelagic community and the effect of cannibalism and intraguild predation on anchovy and sardine dynamics under different environmental conditions.
Abstract: The well-being of humans and their societies depends on goods and services from marine ecosystems. Management of the fish stocks off Northern Chile is based on a single species approach. However, the fish species are not independent, and there is a need to understand the species interactions within the community and with the 3climate variability and human pressures. In this thesis I studied the size-based dynamics of pelagic fish community off Northern Chile.
I investigated temporal effects of climate variability on size-based indicators from the pelagic fishery. I found that catches from the pelagic community have been declining and have become composed of smaller fish. The main signals from the environment were short-term effects, but the trends found were probably combined consequences of climate variability and fishing.
I developed a multispecies size-spectrum model to explore the dynamics of the pelagic community. The model examined the effect of cannibalism and intraguild predation on anchovy and sardine dynamics under different environmental conditions. I found that climate variability and predation interactions are both needed to understand the coexistence and extinction of anchovy and sardine.
The effect of fishing on anchovy dynamics was also explored through the model. Preliminary results showed that fishing below maturity has lower impact on anchovy dynamics than current fishing pattern off northern Chile. In addition the approach of a balanced harvest strategy would be more beneficial for anchovy only when it follows the relative growth rate of the species.
Indicators and models are key tools in implementing the ecosystem-based approach. This thesis has combined these tools with emerging ecological theory about the role of size in the structuring marine ecosystems and, in this way, has set up a basic framework to work towards the ecosystem-based fishery management off Northern Chile.
6 citations
Cites background from "Predicting marine phytoplankton com..."
...The range of prey sizes consumed by a predator expands with increasing predator body size (Scharf et al. 2000, Barnes et al. 2008, 2010b) and moreover, the relation between body mass and population density (numerical abundance) in a log-log space declines in the ocean with slope around…...
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TL;DR: In this article, three types of primary productivity (PP) models were evaluated in a mesoscale area around the South Shetland Islands (Antarctica) using data collected in situ during an oceanographic cruise.
6 citations
TL;DR: In this paper, the authors used remote sensing and geostatistical techniques to demonstrate the influence of key environmental variables (i.e., sea surface temperature, current intensity, wind speed, photosynthetically active radiation and flow of larger rivers) on spatio-temporal variability of chlorophyll-a in the coastal region of Alagoas State, northeastern Brazil.
Abstract: Coastal areas are important regions for global primary productivity. However, understanding the spatio-temporal dynamics of coastal phytoplankton dynamics is challenging due to the multiple environmental factors involved. Here, we use remote sensing and geostatistical techniques to demonstrate the influence of key environmental variables (i.e. sea surface temperature; current intensity; wind speed; photosynthetically active radiation and flow of larger rivers) on spatio-temporal variability of chlorophyll-a in the coastal region of Alagoas State, northeastern Brazil. Chlorophyll-a had high spatial variation (0.03–18.23 mg m−3), with highest mean values observed on the continental shelf up to 50 m depth and towards the southern part of the study area. Seasonally, the highest average values were found between April and June (0.721 mg m−3) and the lowest values between October and December (0.376 mg m−3). Multivariate analysis indicated that the spatio-temporal variability of chlorophyll-a in shallow zones is mainly influenced by seasonal variation in the hydrological regime of rivers and wind-induced coastal currents. This contrasts with deeper zones, where chlorophyll-a variability is strongly linked to water temperature and light availability. Moreover, areas with inshore coral reefs typically had reduced chlorophyll-a levels, possibly due to the blocking of nutrients at river mouths.
6 citations
Cites background from "Predicting marine phytoplankton com..."
...2010) and especially, tropical zones (Pérez et al. 2005; Barnes et al. 2011)....
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...There was a weak and negative correlation between water temperature and chlorophyll-a, a characteristic pattern of subtropical regions (Arnone 1987; Lutz et al. 2010) and especially, tropical zones (Pérez et al. 2005; Barnes et al. 2011)....
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TL;DR: In this article, the probability of taxon occurrence and taxon-specific biomass (mg L−1) of 183 phytoplankton taxa using variables characterizing spatial context, ecosystem size and land cover were used to evaluate responses to anthropogenic stress.
5 citations
References
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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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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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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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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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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