Comparing the carbon and nitrogen fluxes in Ostrea edulis and Crassostrea gigas in the Venice lagoon - Comparison of fluxes undergoing different types of incubations, taking into consideration biofouling on the external part of the shells

Abstract

This master thesis focuses on the European oyster Ostrea edulis, which is considered a keystone species for a variety of different reasons that are going to be explained inside the main text (Gallardi, 2014). O. edulis is considered to be ‘threatened and in decline’, in several areas of European waters. In the last period of time, different countries, have embraced and approved strategies for its conservation and restoration (Rodrigues-Perez, et al., 2019), but also smaller realities are fighting for the same goal. For this analysis, the researcher will work to find out more information, through experimental procedures, on the influence that N and C fluxes of O. Edulis, have on different ecosystem services. Moreover, the same experimental processes, will be applied to another species of oyster found in the lagoon of Venice, Crassostrea gigas, in order to provide a comparison of the two. To measure N and C fluxes, the researcher will use chambers and measure the N and C concentrations with special kits, in order to get an idea of the amounts of each. In this way, the researcher, will have a good overview of the carbon and nitrogen cycles in the oyster beds. The experimental phase will include three main types of incubations in the chambers, to get a wider range of variables and possibilities. The above-mentioned incubation will be done in AMBIENT and ambient plus few degrees (AMBIENT+) conditions, manually controlled in the basins in which the oysters will be kept. The concept behind these incubations is that the same shell (cleaned or not cleaned from epibionts) should be used for the incubation with and without animal, in order to have the same amount of microorganisms (same amount of epibionts and microalgal cells) on top and the same size of shell.