Organic matter features, degradation and remineralisation at two coastal sites in the Ligurian Sea (NW Mediterranean) differently influenced by anthropogenic forcing

Cristina Misic (1) , Michela Castellano (1) , Anabella Covazzi Harriague (1)

1 Dipartimento per lo Studio del Territorio e delle sue Risorse

Organic matter (OM) features, degradation and remineralisation were studied in the seawater of a natural coastal site (Marine Protected Area of Portofino) and at a urbanised coastal site (Quarto, Genoa city) of the Ligurian Sea. The accumulation of low trophic value OM and the persistence of phytoplanktonic biomass throughout the year were observed only at the urbanised site. Efficient OM degradation and remineralisation via high-activity (two times higher than at the Portofino site) hydrolytic enzymatic activities (alkaline phosphatase and leucine aminopeptidase) were recorded. This active degradation indicated a generally good resistance of the Quarto system to environmental pressures (coastal inputs and anthropogenic influence). However, the high potential release of recycled inorganic nutrients and the favourable environmental conditions (i.e. higher seawater temperature at the Quarto site and allochthonous inputs), could encourage unpredictable development of the autotrophic fraction, including an already observed dystrophic blooming of toxic microalgae.

Mots clés: organic matter; enzymatic activity; autotrophic biomass; degradation; remineralisation; coastal waters; urbanisation; Ligurian Sea; NW Mediterranean

Domaines: Sciences du Vivant [q-bio]

Cristina Misic, Michela Castellano, Anabella Covazzi Harriague. Organic matter features, degradation and remineralisation at two coastal sites in the Ligurian Sea (NW Mediterranean) differently influenced by anthropogenic forcing. Marine Environmental Research, 2011, 72 (1-2), pp.67. ⟨10.1016/j.marenvres.2011.05.006⟩. ⟨hal-00720185⟩