Distribution of dissolved iron and bacteria producing the photoactive siderophore, vibrioferrin, in waters off Southern California and Northern Baja
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Phytoplankton blooms can cause acute effects on marine ecosystems due either to their production of endogenous toxins or to their enormous biomass leading to major impacts on local economies and public health. Despite years of effort, the causes of these Harmful Algal Blooms are still not fully understood. Our hypothesis is that bacteria that produce photoactive siderophores may provide a bioavailable source of iron for phytoplankton which could in turn stimulate algal growth and support bloom dynamics. Here we correlate iron concentrations, phytoplankton cell counts, bacterial cell abundance, and copy numbers for a photoactive siderophore vibrioferrin biosynthesis gene in water samples taken from 2017 cruises in the Gulf of California, and the Pacific Ocean off the coast of northern Baja California as well as during a multiyear sampling at Scripps Pier in San Diego, CA. We find that bacteria producing the photoactive siderophore vibrioferrin, make up a surprisingly high percentage of total bacteria in Pacific/Gulf of California coastal waters (up to 9%). Vibroferrin’s unique properties and the widespread prevalence of its bacterial producers suggest that it may contribute significantly to generating bioavailability of iron via photoredox reactions.
KeywordsPhotoactive Siderophores Vibrioferrin Bacteria Pacific ocean Gulf of California Iron HAB
We would like to acknowledge the members of the Marine Ficotoxins Laboratory at CICESE for helping us sampling and providing us the hydrographic data. We would like to thank Professor Helmut Maske from the Marine Microbes Laboratory at CICESE for use of his facilities and César Almeda for his assistance with the maps. We specially acknowledge Baja Aqua Farms Co. for sponsoring the entire Pacific Ocean research cruise. This work was supported in part by grant CHE-1664657 from the National Science Foundation. RCL was partially supported by the National Council of Science and Technology (CONACYT-México) project FORDECYT M0037-2015-02-260040 (to EGM), and a Postdoctoral fellowship for overseas (CONACYT-México). The Scripps Pier phytoplankton cell counts and chlorophyll concentrations were collected as part of the Southern California Coastal Ocean Observing System, Harmful Algal Bloom Monitoring Program with support in part by grant NOAA-NA16NOS0120 from the National Oceanic and Atmospheric Administration.
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