Marine Submerged Soils in Torre Del Cerrano Park, Adriatic Sea (Italy).

Intertidal habitats have recently captured the attention of many pedologists. The first research on sub-tidal soils was conducted in the USA (Sinepuxent Bay, Maryland; Indian River Bay, Delaware), where shallow water sediments showed to undergo pedogenic processes in subaqueous landscapes. For these submerged soils, a revision of the equation for soil formation was proposed so as to include genesis and distribution of subaqueous soil. This entrance followed a change by the USDA—NRCS in soil definition when they published the second edition of the Soil Taxonomy. The revised definition allowed pedologists to define “subaqueous soils” as what marine scientists traditionally identified as sub-tidal sediments or sedimentary deposits. In order to evaluate the anthropic pressure on the evolution and quality of the submarine soils, we studied subaqueous soil transects within a Marine Park of the Adriatic sea (Italy). We compared disturbed (trawling fishing) and undisturbed (protected for 7 years) soils at the bathymetries of 2, 4, 6, and 8 m. Soils were retrieved by a mechanical grab bucket mounted on a boat, and removed by using a plastic blade that allowed us to obtain stable and relatively undisturbed soil profiles showing the first 2 or 3 horizons. The profiles were morphologically described with ancillary characteristics as well, such as the presence and number of animals (e.g., bivalves, gastropods, worms). Vegetation was absent. Samples were dried and analyzed for their main physical, chemical and biological properties. In both marine areas, even at 8 m of bathymetry, we observed great morphological and analytical differences between the superficial C horizon (recently deposited sediments) and the underlying A horizon (pedogenized sediments), and attributed the changes to marine organisms living in the A horizon (mainly bivalves). Hence, submarine soils are important examples of pedogenesis led by animals. Their bioturbation and the excretion of organics foster the activity of a microbial population able to change C horizons into A horizons. Analogous to the “rhizosphere effect”, which is often responsible of considerable pedogenic changes, we would refer to this phenomenon as a “zoosphere effect”, whose action is mainly detectable in Wassents. We also provide a theoretical reinforcement to the submarine pedogenesis debate arguing in favor of the recognition of soil horizons to bathymetry of at least 8 m.