Research > Current Projects > Documenting Multiple Phycotoxins in Coastal Ecosystems of the California Coast
David A. Caron, Professor, University of Southern California
Avery O. Tatters, Postdoctoral Investigator, University of Southern California
Eric A. Webb, Associate Professor, University of Southern California
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The confluence of freshwater and marine ecosystems along the coast of Southern California can be affected by multiple toxins of either freshwater or marine origin. The geographic distribution and types of these chemical threats is presently unknown, making it difficult to understand or predict the threats posed to animal health in estuaries and lagoons as well as threats to human health through the contamination of seafood.
The widespread occurrence of marine harmful algal blooms and their toxins (in particular domoic acid and saxitoxins) in coastal waters of California has been documented during the last 15 years. In contrast to these ‘showcase’ marine phycotoxins (toxic chemicals synthesized by photosynthetic organisms), there is a paucity of research on many other algal and cyanobacterial toxins that occur in our coastal environment.
This research is designed to: (1) determine the extent of known or presently-undocumented phycotoxins in Southern Californian coastal waters and estuarine ecosystems; (2) isolate, culture and identify the cyanobacteria/algae that are the origin of the toxins; (3) obtain greater understanding of the phycotoxins at ‘hot spots’ identified within the region; (4) establish the basic physiological tolerances (temperature, salinity) of these species and their effects on toxin production; and (5) provide information for the development of future monitoring practices.
This research is a combination of field and laboratory studies to characterize the extent and distribution of these toxins, to identify the causative species, and assess their environmental tolerances. We hypothesize that freshwater habitats of urbanized and developed land stimulate the growth of diverse and potentially toxic cyanobacterial/algal assemblages, creating ‘hot spots’ of complex matrices of toxins in estuaries and along coastlines.
The overarching objectives of this research project are to build awareness of the presence of undocumented phycotoxins in estuaries and coastal regions adjacent to freshwater discharge along the coast of the Southern California Bight, and to provide insight into the causative species for these toxins through isolation and culture of toxin-producing species. The longer-term goal is to contribute to the establishment of guidelines for monitoring potentially toxic species and their harmful products in estuarine environments throughout the region.
2017 Research Update:
Field surveys of cyanobacterial/algal species and their toxins in southern California estuarine ecosystems have been completed. Results show a large number of potentially toxic species of cyanobacteria from over 50 locations along the coast of Southern California. Most sampling sites have multiple species of potentially toxic genera of cyanobacteria present, and multiple cyanobacterial toxins were documented at 23% of the sites examined. Although only half way done with the project, the key findings to date already have been summarized in a recent publication in the journal “Toxins.” Additionally, the establishment of a culture collection of cyanobacterial species has provided a community resource for further research. The culture collection will be made publicly available as it is established and curated.
Publication: Tatters AO, Howard MDA, Nagoda C, Busse L, Gellene AG, Caron DA (2017). Multiple stressors at the land-sea interface: cyanotoxins at the land-sea interface in the Southern California Bight. Toxins 9:95. DOI: 10.3390/toxins903095
Caption, above: A range of cyanobacteria genara encountered in this study; credit: Caron Lab; Avery Tatters.