Fonda, S. University of Trieste,

Mucus macroaggregates covering thousands Km2 of sea surface in 1988, 1989 and 1991 summers, and with less extension in 1997, were recorded in the Northern Adriatic Sea since 1729. Firstly they appeared in the water column as flocks, then as spider webs, as strings up to 8 m long, later as clouds (2 m of diameter and up to 7 m long) which floated up and down, reaching the surface and then forming surface mucus mats. This process can last up to three months. Several hypotheses tried to explain their formation: e.g. increase of plankton and/or benthic diatom or cyanobacteria production which lead to an increase of marine snow, lacking of grazing pressure, changes in phytoplankton community, higher exudation of diatoms under severe N and P limitation, development of a strong pycnocline, bacteria and/or phytoplankton viral infections, high C/P of the refractory DOM produced by efficient bacterial P reminalization. Recent findings indicate that macroaggregates formation could be due to bacterial activity on exuded material which lead to increasing refractory DOM, and changing its molecular structure. In some years particular hydrographic conditions (e.g. reduced dense water formation, prevalence of southern winds) could enhance its accumulation, resulting in macroaggregates formation.
Day: Monday, Feb. 1
Time: 02:15 - 02:30pm
Location: Sweeney Center
Code: SS17MO0215S