Characterisation of European Marine Sites: Essex Estuaries European Marine Site Occasional Publication of the Marine Biological Association 17

This report provides an overview of water and sediment quality within the Essex Estuaries European Marine Site (EMS) and examines evidence for their influence on biological condition. Site characterisation has been accomplished by review of published literature and unpublished reports, together with interrogation of summary data sets for tidal waters provided by EA.

Multiple environmental controls on phytoplankton growth strategies determine adaptive responses of the N : P ratio

The controls on the 'Redfield' N:P stoichiometry of marine phytoplankton and hence the N:P ratio of the deep ocean remain incompletely understood. Here, we use a model for phytoplankton ecophysiology and growth, based on functional traits and resource-allocation trade-offs, to show how environmental filtering, biotic interactions, and element cycling in a global ecosystem model determine phytoplankton biogeography, growth strategies and macromolecular composition. Emergent growth strategies capture major observed patterns in marine biomes. Using a new synthesis of experimental RNA and protein measurements to constrain per-ribosome translation rates, we determine a spatially variable lower limit on adaptive rRNA:protein allocation and hence on the relationship between the largest cellular P and N pools. Comparison with the lowest observed phytoplankton N:P ratios and N:P export fluxes in the Southern Ocean suggests that additional contributions from phospholipid and phosphorus storage compounds play a fundamental role in determining the marine biogeochemical cycling of these elements.