Abstract
This study reports on the harmful algal bloom (HAB) dinoflagellate Akashiwo sanguinea in the upper, mid and lower Caloosahatchee estuary, Florida during monthly sample events at four sites from February 2009 through February 2010. Akashiwo sanguinea cells were microscopically quantified throughout the course of the study and scanning electron microscopy was used to confirm certain life stage observations. Water temperature and salinity were recorded for each collection. A rare observation of a major sexual reproduction event was made from water samples collected in situ during February 2009. This sample event included 600 cells ml−1 of small cells, 25 cells ml−1 of perpendicularly connected cells in the fusing position, 17 cells ml−1 of planozygotes, cells surrounded by mucoid halos and asexual pairs. Structures consistent with a fertilization tube in the apical or sulcal regions of the small cells were also observed. A bloom of A. sanguinea vegetative cells was observed in the upper estuary in May with cell densities near 700 cells ml−1 and again in June with densities greater than 300 cells ml−1. Results provide insights into environmental conditions during the occurrence of reproduction stages and vegetative cell blooms of A. sanguinea.
About the authors

Susan Badylak is a Senior Biological Scientist in the Fisheries and Aquatic Sciences Program at the University of Florida. Since joining the program in 1988 she has researched phytoplankton community structure and ecology in a wide range of freshwater and marine ecosystems, including Florida Bay, Lake Okeechobee, Indian River Lagoon, St. Lucie Estuary, Tampa Bay, Apalachicola Bay, Suwannee River estuary, the St. Johns River and the Caloosahatchee River estuary.

Edward J. Phlips has been a Professor at the University of Florida since 1983. He has studied the ecology of algae in a wide range of freshwater and marine ecosystems in Florida and around the world, with an emphasis on harmful algal blooms and the effects of eutrophication and changes in climate.

Ashley Loren Mathews received a PhD in Fisheries and Aquatic Sciences from the University of Florida in 2013. She is currently a faculty member at Georgia Southern University in Statesboro, Georgia. Her research and teaching is focused on the ecology and productivity of coastal marine ecosystems.

Karen Kelley is the Scientific Research Manager of the ICBR Electron Microscopy Core Laboratory at the University of Florida. She has engaged in an extensive range of studies using high power scanning electron and transmission microscopy in microbiological and medical research.
Acknowledgments
The research was partially funded by the South Florida Water Management District, W. Palm Beach, Florida and the College of Agriculture and Life Sciences, University of Florida, Gainesville, Florida, USA.
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