A mesocosm experiment at MEDIMEER, Sète, France, April 2018
An in situ mesocosm experiment is currently running (April 2018) as a part of the PHOTOPHYTO project funded by the French National Research Agency (ANR). This experiment focuses on the effects of global warming on the timing of marine phytoplankton blooms taking into account the different interactions between biotic and abiotic components, especially the match/mismatch between predators and prey.
The 12 in situ mesocosms are immersed in the natural water column and their water temperatures follow the natural water temperature variations during the day/night periods as well all along the duration of the experiment. The water temperatures of 6 mesocosms are increased and maintained around +3°C relative to the other 6 in situ mesocosms (Vidussi et al. 2011).
In order to study the effects of warming on different size fractions of zooplankton community as predators, and the consequences on the functioning of the marine plankton food web, four treatments (each in triplicate mesocosms) are applied:
- Natural water temperature, and natural water screened on 1000 µm,
- +3°C higher than natural water temperature, and natural water screened on 1000 µm,
- Natural water temperature, and natural water screened on 200 µm, and
- +3°C higher than natural water temperature, natural water screened on 200 µm
In the April 2018 mesocosm experiment, the large majority of physicochemical parameters and biological ones such as abundances, biomasses of organisms and related processes (primary production, respiration, growth, grazing, etc.) are investigated by the scientists involved in the PHOTOPHYTO consortium: MARBEC laboratory of CNRS-University of Montpellier-Ifremer-IRD and their collaborators from MEDIMEER of OSU-OREME and from LOMIC laboratory of CNRS-Sorbonne University. In addition, we have the pleasure to have several successful applicants of AQUACOSM Transnational Access involved in this mesocosm experiment:
Dr. Nicole ABERLE-MALZAHN (Associate Professor at the Department of Biology, Norwegian University of Science and Technology, NTNU, Norway) and Katharina BADING (PhD student at the Department of Biology, Norwegian University of Science and Technology, NTNU, Norway) participate in this experiment as a group of scientists. They study the dynamics of microzooplankton during the mesocosm experiments and the link between microzooplankton and larval fish (European sea bass Dicentrarchus labrax) under present and future ocean conditions. The aim is to relate temperature-induced changes in microzooplankton (e.g. growth, biomass, timing, community composition and diversity) to physiological and behavioral traits of larval fish (e.g. growth, grazing, survival, fitness, selective feeding).
Moreover, we have also the pleasure to have three trainees who are involved in this mesocosm experiment:
– Maria PROTOPAPA, a PhD student of Hellenic Center for Marine Research, Anavissos (Greece) who helps for several samplings especially for the zooplankton and analyzes the zooplankton and their eggs.
– Katerina SYMIAKAKI, a MSc student from University of Crete, Heraklion (Greece), who participates to several tasks like DNA filtration and help for preparation of the experiments for the net oxygen production and respiration.
– Ariadna GARCÍA-ASTILLERO HONRADO, a student from Rey Juan Carlos University of Móstoles (Spain). She participates in sampling and help for nutrients analyzing.
All trainees help also the samplings and parallel experimentations especially that of link between microzooplankton and larval fish.
Vidussi F, Mostajir B et al. (2011). Effects of experimental warming and increased ultraviolet B radiation on the Mediterranean plankton food web. Limnology & Oceanography 56 (1): 206-218