Carolyn Faithfull

Transfer of bacterial production based on labile carbon to higher trophic levels in an oligotrophic pelagic system

Additions of labile organic carbon (C) enhanced bacterial production (BP) and were associated with increases in crustacean zooplankton and planktivorous fish biomasses. This was shown in a mesocosm ...

Testing the light : nutrient hypothesis in an oligotrophic boreal lake

Anthropogenic changes in the nitrogen (N), phosphorus (P), and carbon (C) cycles have altered nutrient concentrations and the light climate in freshwaters globally. These factors affect phytoplankt ...

Terrestrial runoff boosts phytoplankton in a Mediterranean coastal lagoon, but these effects do not propagate to higher trophic levels

Abstract Heavy rainfall events causing significant terrestrial runoff into coastal marine ecosystems are predicted to become more frequent with climate change in the Mediterranean. To simulate the effects of soil runoff on the pelagic food web of an oligotrophic Mediterranean coastal lagoon, we crossed soil extract addition (increasing nutrient availability and turbidity) and fish presence in a full factorial design to coastal mesocosms containing a natural pelagic community. Soil extract addition increased both bacteria and phytoplankton biomass. Diatoms however profited most from soil extract addition, especially in the absence of fish. In contrast zooplankton and fish did not profit from soil extract addition. Furthermore, our data indicate that nutrients (instead of light or carbon) limited basal production. Presumed changes in carbon availability are relatively unimportant to primary and secondary production in strongly nutrient limited systems like the Thau Lagoon. We conclude that in shallow Mediterranean coastal ecosystems, heavy rainfall events causing soil runoff will (1) increase the relative abundance of phytoplankton in relation to bacteria and zooplankton, especially in the absence of fish (2) not lead to higher biomass of zooplankton and fish, possibly due to the brevity of the phytoplankton bloom and the slow biomass response of higher trophic levels.

An Operational Framework for the Advancement of a Molecule-to-Biosphere Stoichiometry Theory

Biological stoichiometry is an approach that focuses on the balance of elements in biological interactions. It is a theory that has the potential to causally link material processes at all biological levels – from molecules to the biosphere. But the lack of a coherent operational framework has so far restricted progress in this direction. Here, we provide a framework to help infer how a stoichiometric imbalance observed at one level impacts all other biological levels. Our framework enables us to high the areas of the theory in need of completion, development and integration at all biological levels. Our hope is that this framework will contribute to the building of a more predictive theory of elemental transfers within the biosphere, and thus, to a better understanding of human-induced perturbations to the global biogeochemical cycles.

Pelagic energy mobilization across crossed gradients of phosphorus and dissolved organic carbon in a chemostat experiment

Pelagic production depends on biological energy mobilization based on both light energy mobilized by phytoplankton and imported energy bound as allochthonous organic carbon (AOC) and utilized by ba ...