Elevated sea surface temperatures are increasing the prevalence of pathogenic bacteria at higher latitudes. The recent increase in Vibrio-related wound infections and deaths, the latter often related to Vibrio vulnificus, along the Baltic coasts is therefore of serious concern. Recently, the eelgrass Zostera marina has been suggested to reduce Vibrio spp. abundance on surrounding waters, potentially mitigating the problem at the local scale. In this context, our question was which environmental and biological factors regulate Vibrio dynamics in and outside of eelgrass meadows in the Baltic Sea. For three coastal sites of different salinities (from 6 to 21 PSU) in Denmark, Germany, and Finland we sampled within eelgrass meadows as well as 15 m and 100 m outside, monitoring the absolute and relative abundances of the genus Vibrio and V. vulnificus in the water column and sediment. In contrast to our expectations, we found that Vibrio spp. was usually accumulated in eelgrass meadows. Vibrio vulnificus correlated at salinities of 8–11.4 PSU with warm temperatures, bacterial abundance, and turbidity in July and August, peaking at 10⁴–10⁵ gene copies L^-1. Sediment appeared to accumulate V. vulnificus and could be a potential source of this pathogen in the water column. At the conference, a temporal model integrating all measured parameters, explaining the temporal dynamics of opportunistic Vibrio pathogens in coastal Baltic Sea waters, will be presented.

Primary Presenter: Victor Fernandez Juarez, University of Copenhagen (victor.fj@bio.ku.dk)

Authors:

Victor Fernández-Juarez, University of Copenhagen   (victor.fj@bio.ku.dk)

David Riedinger, Leibniz Institute for Baltic Sea Research Warnemünde (IOW)  (david.riedinger@io-warnemuende.de)

Luis Fernando Delgado, KTH Royal Institute of Technology  ()

Joao Gusmao, Åbo Akademi University  (joao.gusmao@abo.fi)

Guillem Coll Garcia, Marine Microbiology Group, IMEDEA CSIC-UIB (Esporles, Spain)  (g.coll@imedea.uib-csic.es)

Vasiliki Papazachariou, University of Copenhagen   (vasiliki.papazachariou@bio.ku.dk)

Christian Pansch, Åbo Akademi University  (cpanschh@abo.fi)

Anders F. Andersson, KTH Royal Institute of Technology  ()

Mathias Labrenz, Leibniz Institute for Baltic Sea Research Warnemünde (IOW)  (matthias.labrenz@io-warnemuende.de)

Lasse Riemann, University of Copenhagen   (lriemann@bio.ku.dk)