Mechanism of Mucilage Formation in the North Adriatic Sea: A Component of CREICO (Cooperative Research on Ecological Interactions in the Coastal Oceans)

University Of California-San Diego Scripps Inst Of Oceanography, La Jolla CA

Investigators

Abstract

The proposed research is a component of CREICO (Cooperative Research on Ecological Interactions in the Coastal Oceans) program in the Adriatic Sea. This international initiative is intended to develop cooperation between Croatia, Slovenia, Italy and the US in environmental science in the Adriatic, in concert with Adriatic Observing System (CAOS) being developed with NOAA. CREICO is intended to increase understanding of the structure and function of ecological systems in the Adriatic, and the system response to perturbations. The focus of CREICO is on "bloom phenomena" and their causes and consequences. This proposal focuses on the mucilage phenomenon (mare sporco). Over the last 3 centuries, enormous accumulations of "mucilage" have occurred along the coasts of the northern Adriatic Sea, affecting the coasts of Italy, Slovenia and Croatia. The cause remains a mystery. Mucilage events damage local fisheries and tourism. Scientifically, the huge organic matter accumulation represents an opportunity to study the ecosystem level mechanisms of variability in the carbon biogeochemistry, and North Adriatic offers a natural "laboratory." Predicting the mucilage events would be an excellent test of models of oceanic carbon biogeochemistry. While phytoplankton blooms produce the organic matter that ultimately forms mucilage Dr. Azam hypothesizes that bacterial processing of phytoplankton biomass, to produce slow?to-degrade polysaccharide plays a significant role. They will test hypotheses on bacterial production of slow?to-degrade dissolved and colloidal organic matter (including bacterial capsular material and exudates) and its aggregation to form mucilage under relevant ecosystem conditions. This work will be done in collaboration with Serena Fonda?Umani (Italy), Vera Zutic (Croatia) and Valentina Turk (Slovenia). They will use mesocosms (in Fonda?Umani lab in Trieste, Italy) to test hypotheses through perturbation experiments. Further, they will take advantage of the planned two 15?d cruises. Bacterial studies will use molecular approaches, to explore species?specific roles in mucilage production and decomposition. Polysaccharide structure analysis will seek relationships between bacterial biochemical profiles and polysaccharide utilizability. Dr. Azam and his lab have been informally collaborating with Italian, Slovenia and Croatian marine scientists and students on mucilage studies, in research and training. This research will increase this collaboration; it will address a long?standing oceanographic problem, with potential of discovering fundamental principles of carbon cycling of relevance to research on global change.