Harmful algal species in the Central Basin of Puget Sound: Seasonal bloom patterns analyzed via FlowCAM technology

The Central Basin of Washington State’s Puget Sound is part of the larger estuarine system known as the Salish Sea. Long-term monitoring of this basin by King County has produced a robust dataset through the year-round collection of a suite of physical, chemical, and biological parameters. A phytoplankton monitoring program was established in 2008 using traditional microscopy methods and in 2014 a particle imaging system was added to the program. Complex interplay among a number of environmental factors contribute to the distribution and magnitude of annual phytoplankton blooms within the estuary, which regularly include several species considered potentially harmful because they are associated with shellfish poisoning, fish kills, or other harmful effects on local biota. The study of these communities, their distributions, and their ecological drivers is vital to the understanding and preservation of the local wildlife and human health. Surface water samples from 10 marine stations spanning Point Wells to East Passage are collected bi-monthly and analyzed via FlowCAM (Fluid Imaging Technologies), a particle imaging system operating in the 10-300µm particle range. Key water column indicators (temperature, salinity and nutrients) are collected concurrently to these biological samples. Using parameters such as size, particle edge gradient, and color the FlowCAM aids in the identification and quantification of sixty taxonomic categories, several of which are species considered potentially harmful and are regularly detected using this method. Potentially harmful species common to the Central Basin include, but are not limited to: Akashiwo sanguinea, Alexandrium catenella, Dinophysis spp., Heterosigma akashiwo, and some Pseudo-nitzschia species. Significant changes in physical conditions have been recorded for the Salish Sea in the last several years, with notably higher than normal temperatures beginning in late 2014; our data analysis examines how shifting environmental conditions may impact the abundance and distribution of potentially harmful taxa in the Central Basin