Climate change and the potential spreading of marine mucilage and microbial pathogens in the Mediterranean Sea.
BACKGROUND
Marine snow (small amorphous aggregates with colloidal properties) is present in all oceans of the world. Surface water warming and the consequent increase of water column stability can favour the coalescence of marine snow into marine mucilage, large marine aggregates representing an ephemeral and extreme habitat. Marine mucilage characterize aquatic systems with altered environmental conditions.


RESULTS
We investigated, by means of molecular techniques, viruses and prokaryotes within the mucilage and in surrounding seawater to examine the potential of mucilage to host new microbial diversity and/or spread marine diseases. We found that marine mucilage contained a large and unexpectedly exclusive microbial biodiversity and hosted pathogenic species that were absent in surrounding seawater. We also investigated the relationship between climate change and the frequency of mucilage in the Mediterranean Sea over the last 200 years and found that the number of mucilage outbreaks increased almost exponentially in the last 20 years. The increasing frequency of mucilage outbreaks is closely associated with the temperature anomalies.


CONCLUSIONS
We conclude that the spreading of mucilage in the Mediterranean Sea is linked to climate-driven sea surface warming. The mucilage can act as a controlling factor of microbial diversity across wide oceanic regions and could have the potential to act as a carrier of specific microorganisms, thereby increasing the spread of pathogenic bacteria.
Danovaro
Roberto
R
Department of Marine Sciences, Polytechnic University of Marche, Ancona, Italy. r.danovaro@univpm.it
Fonda Umani
Serena
S
Pusceddu
Antonio
A
D002980:Climate; D057231:Climate Change; D003102:Colloids / Q000737:chemistry; D004777:Environment; D005782:Gels / Q000737:chemistry*; D017404:In Situ Hybridization, Fluorescence; D008386:Marine Biology; D008522:Mediterranean Sea; D012623:Seawater / Q000382:microbiology / Q000821:virology; D013045:Species Specificity; D013696:Temperature; D014867:Water / Q000737:chemistry; D014871:Water Microbiology
D003102:Colloids; D005782:Gels; D014867:Water