<span style="mso-fareast-font-family: Arial;">Warmer Oceans Will Increase Abundance of Human Pathogens on Seaweeds

Anthropogenic warming of the world&rsquo;s oceans is not just an environmental crisis but can result in a significant threat to human health. A combination of a warming ocean and increased human activity in coastal waters sets the stage for increased pathogenic Vibrio-human interaction. Warming patterns due to climate change have already been related to the emergence of Vibrio outbreaks in temperate and cold regions. Seafood, including seaweeds is uniquely poised to contribute to global food and nutrition security. In recent years there has been a resurgence of interest in seaweeds due to its many uses, its high nutritional value, and its ability to provide ecosystem services, such as habitat provision, carbon and nutrient uptake, and coastal protection. However, some seaweed species can be a reservoir for harboring pathogenic Vibrio and illnesses like gastroenteritis have recently been associated with foods prepared with seaweeds. Here we investigated the impact of elevated water temperatures on the abundance of major human pathogens Vibrio parahaemolyticus, Vibrio alginolyticus and Vibrio vulnificus/cholerae in seaweed and coastal waters. Three seaweed species, Fucus serratus, Palmaria palmata, and Ulva spp. were exposed to temperature treatments (16&deg;C and 20&deg;C) to assess effects of mean temperature rise on Vibrio parahaemolyticus, Vibrio alginolyticus and Vibrio vulnificus/cholerae colonisation. Colony-forming units (CFU) were counted from seaweed surfaces and surrounding water. F. serratus and P. palmata showed significantly higher Vibrio abundance at higher temperatures compared to Ulva spp., however, temperature did not significantly affect abundance of tested Vibrio species in surrounding waters. These results indicate that certain seaweed species may serve as major hotspots for human pathogenic bacteria in warmer conditions with implications for human health.