P E R S E O

Macroecological patterns in marine phytoplankton

 

 

A research project funded by

Ministerio de Ciencia e Innovación

(CTM2008-03999)

Ministerio de Ciencia e Innovación - Gobierno de España

 

 

 

Background

Participants

Objectives

Work packages

Progress

Publications

Diatoms, SEM


Background

Phytoplankton constitute the basis of the ecological food web in most marine ecosystems and therefore play a major role in regulating the exchange of carbon dioxide between the ocean and the atmosphere, as well as in sustaining upper trophic levels. Two main factors, size structure and taxonomic composition, are the key determinants of the ecological and biogeochemical role of phytoplankton, and both can be altered by current and future processes of global change. Hence, there is a pressing need to determine the factors that control phytoplankton size structure and taxonomical composition and to characterize general macroecological patterns of phytoplankton abundance, diversity and metabolism in the ocean. Our project stems from the general hypothesis that nutrient supply determines the size structure and functional group composition of phytoplankton communities, and therefore the trophic and biogeochemical functioning of pelagic ecosystems. We will address this hypothesis using laboratory experiments with monospecific cultures, field observations across a coast to shelf productivity gradient, and nutrient addition experiments with natural assemblages. These observations and experiments will allow us to construct allometric models relating cell size to the main metabolic rates in phytoplankton (photosynthesis, nutrient uptake, respiration, exudation, cell lysis) and to identify macroecological patterns linking nutrient supply, phytoplankton metabolism and community structure.


Participants

logotipo principal da Universidade de Vigo

Emilio Marañón (PI)

Pedro Cermeño

Cristina Sobrino

María Huete-Ortega

Tamara Rodríguez

Daffne López-Sandoval

Ana Fernández

 

Universidad de Málaga

 

Jaime Rodríguez

José María Blanco

 

Inicio URJC

 

Natalia González


Objectives

1. To determine the size-scaling relationships for key metabolic processes in phytoplankton across a wide range of cell sizes and taxonomic affiliations.

2. To test the hypothesis that the size-scaling of metabolic rates in phytoplankton follows the ¾-power rule.

3. To determine general macroecological patterns of size- and taxon-dependent phytoplankton metabolic rates over a wide range of productivity conditions.

4. To test the hypothesis that nutrient supply controls the response and ecological success of different phytoplankton size classes and functional groups.

5. To determine general macroecological patterns that relate water column structure and nutrient availability to phytoplankton abundance, diversity and size-structure.

 

 


Work packages

Work package 1. Size- and taxon-dependent metabolism in monospecific cultures.

This WP aims to determine the size-scaling relationships for critical metabolic rates (both anabolic and catabolic) in optimal and sub-optimal growth conditions across a wide range of cell sizes and considering also a variety of taxonomic groups. This work package will allow us to test the hypothesis that the size-scaling of metabolic rates in phytoplankton frequently deviates from the predictions of the general allometric theory due to taxon-related changes in resource uptake and use.

Work package 2. Field observations and database analyses.

The objective of this WP is to determine general patterns of size- and taxon-dependent phytoplankton abundance and metabolism across a range of productivity conditions. Measurements will be carried out during the upwelling-favourable season in the Ría de Vigo and also in the adjacent shelf. In addition, measurements will also be conducted during open-ocean transects taking advantage of cruises already programmed within the framework of other projects. The analysis of existing databases will also be used to extract general patterns relating hydrodynamics with phytoplankton cell size, abundance, and metabolic rate.

Work package 3. Nutrient addition experiments with natural assemblages.

By performing realistic nutrient addition experiments to natural phytoplankton assemblages, we will test the hypothesis that nutrient supply dynamics (rate of nutrient supply, amount of nutrient added and frequency of pulses) control the response and ecological success of different phytoplankton size classes and functional groups. In particular, we will test the hypothesis that the variability in nutrient supply rates, rather than just the total amount of nutrients available, is a critical factor controlling the competitive success of diatoms.

 


Progress

 

WP1. We have determined carbon and nitrogen cell quotas, growth rates and key metabolic rates (photosynthesis, exudation, respiration, nutrient uptake) in >20 different species spanning >7 orders of magnitude in cell size, and including cyanobacteria, chlorophytes, coccolithophores, dinoflagellates and diatoms. Measurements were done during both the exponential growth and the senescent phases.

 

 

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WP2. We have conducted 8 sampling visits to stations in the Ría de Vigo and in the adjacent shelf during May – July 2010. On each visit, we collected samples to determine phytoplankton abundance, composition and size structure, together with the rates of carbon fixation, exudation and respiration. Additional measurements of phytoplankton abundance, size structure and metabolism have been collected during large-scale transects in the Mediterranean Sea and in the tropical Atlantic Ocean

 

 

WP3. We are using continuous cultures (chemostats) to determine the interactive effects of temperature and resource supply on phytoplankton growth and metabolism.


Publications

Huete-Ortega, M., Marañón, E., Varela, M., Bode, A. (2010) General patterns in the size scaling of phytoplankton abundance in coastal waters during a 10-year time series. Journal of Plankton Research, 32, 1-14.

López-Sandoval, D. C., Fernández, A., Marañón, E. (2011) Dissolved and particulate primary production along a longitudinal gradient in the Mediterranean Sea. Biogeosciences, 8, 815-825.

Huete-Ortega, M., Calvo-Díaz, A., Mouriño-Carballido, B., Graña, R., Marañón, E. (2011) Effect of environmental forcing on the biomass, production and growth rate of size-fractionated phytoplankton in the central Atlantic. Journal of Marine Systems, 88, 203-213.

Huete-Ortega, M., Cermeño, P., Calvo-Díaz, A., Marañón, E. (2011) Isometric size-scaling of metabolic rate and the size abundance distribution of phytoplankton. Proceedings of the Royal Society B, doi:10.1098/rspb.2011.2257. 

Marañón, E., Cermeño, P., Latasa, M., Tadonléké, R. M. (2012) Temperature, resources, and phytoplankton size structure in the ocean. Limnology and Oceanography, 57, 1266-1278

Marañón, E., Cermeño, P. López-Sandoval, D. C., Rodríguez-Ramos T., Sobrino, C., Huete-Ortega, M., Blanco, J. M., Rodríguez, J. (2013) Unimodal size scaling of phytoplankton growth and the size dependence of nutrient uptake and use. Ecology Letters, doi: 10.1111/ele.12052  

López-Sandoval, D. C., Rodríguez-Ramos, T., Cermeño, P., Marañón, E. (2013) Cell size- and taxon-dependence of organic carbon exudation in marine phytoplankton. Marine Ecology Progress Series, in press.


Last updated December 2012