Resting vs active stages in plankton dynamics (southern Italy, Ionian Sea, Mediterranean)

Marine coastal plankton undergoes seasonal fluctuations and interannual variations in its composition mainly justified with the alternance of active stages in the water column and resting stages (cysts) in the sediments. As a consequence, to fully understand the functioning of planktonic system in marine coastal areas we need to integrate information coming from pelagos and benthos into a continuum that could help us to quantify the transfer of biodiversity between these two domains. To achieve this goal we propose an experimental design to gain information from the key elements in plankton dynamics. We consider (in brackets the sampler used): active stages dynamics in the water column (Niskin bottles, plankton nets); cyst production (sediment traps); cyst accumulation (sediment cores); cyst germination (inverted traps, Niskin bottles very close to the sediment). In a first attempt carried out in 2010-2011 in the Mr Piccolo of Taranto (Ionian Sea, Mediterranean), the study was structured in two times: autumn mainly to observe the encystment dynamics, and spring, to observe the excystment and its consequence on the water column. Different species showed different behaviours so justifying the unpredictability of confined coastal areas plankton dynamics.