Temperature and residence time controls on an estuarine harmful algal bloom : modeling hydrodynamics and Alexandrium fundyense in Nauset estuary
Ralston, David K.
Brosnahan, Michael L.
Fox, Sophia E.
Lee, Krista D.
Anderson, Donald M.
MetadataShow full item record
KeywordHarmful algal bloom; Hydrodynamic-biological model; Alexandrium fundyense; Residence time; Cyst germination; Growing degree day
A highly resolved, 3-d model of hydrodynamics and Alexandrium fundyense in an estuarine embayment has been developed to investigate the physical and biological controls on a recurrent harmful algal bloom. Nauset estuary on Cape Cod (MA, USA) consists of three salt ponds connected to the ocean through a shallow marsh and network of tidal channels. The model is evaluated using quantitative skill metrics against observations of physical and biological conditions during three spring blooms. The A. fundyense model is based on prior model applications for the nearby Gulf of Maine, but notable modifications were made to be consistent with the Nauset observations. The dominant factors controlling the A. fundyense bloom in Nauset were the water temperature, which regulates organism growth rates, and the efficient retention of cells due to bathymetric constraints, stratification, and cell behavior (diel vertical migration). Spring-neap variability in exchange altered residence times, but for cell retention to be substantially longer than the cell doubling time required both active vertical migration and stratification that inhibits mixing of cells into the surface layer by wind and tidal currents. Unlike in the Gulf of Maine, the model results were relatively insensitive to cyst distributions or germination rates. Instead, in Nauset, high apparent rates of vegetative cell division by retained populations dictated bloom development. Cyst germination occurred earlier in the year than in the Gulf of Maine, suggesting that Nauset cysts have different controls on germination timing. The model results were relatively insensitive to nutrient concentrations, due to eutrophic conditions in the highly impacted estuary or due to limitations in the spatial and temporal resolution of nutrient sampling. Cell loss rates were inferred to be extremely low during the growth phase of the bloom, but increased rapidly during the final phase due to processes that remain uncertain. The validated model allows a quantitative assessment of the factors that contribute to the development of a recurrent harmful algal bloom and provides a framework for assessing similarly impacted coastal systems.
Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Estuaries and Coasts 38 (2015): 2240-2258, doi:10.1007/s12237-015-9949-z.
Showing items related by title, author, creator and subject.
Historic 2005 toxic bloom of Alexandrium fundyense in the western Gulf of Maine : 2. Coupled biophysical numerical modeling He, Ruoying; McGillicuddy, Dennis J.; Keafer, Bruce A.; Anderson, Donald M. (American Geophysical Union, 2008-07-26)A coupled physical/biological modeling system was used to hindcast a massive Alexandrium fundyense bloom that occurred in the western Gulf of Maine in 2005 and to investigate the relative importance of factors governing ...
Distribution of Alexandrium fundyense (Dinophyceae) cysts in Greenland and Iceland, with an emphasis on viability and growth in the Arctic Richlen, Mindy L.; Zielinski, Oliver; Holinde, Lars; Tillmann, Urban; Cembella, Allan D.; Lyu, Yihua; Anderson, Donald M. (2016-04)The bloom-forming dinoflagellate Alexandrium fundyense has been extensively studied due its toxin-producing capabilities and consequent impacts to human health and economies. This study investigated the prevalence of resting ...
Investigating the importance of sediment resuspension in Alexandrium fundyense cyst population dynamics in the Gulf of Maine Butman, Bradford; Aretxabaleta, Alfredo L.; Dickhudt, Patrick J.; Dalyander, P. Soupy; Sherwood, Christopher R.; Anderson, Donald M.; Keafer, Bruce A.; Signell, Richard P. (Elsevier, 2013-11-05)Cysts of Alexandrium fundyense, a dinoflagellate that causes toxic algal blooms in the Gulf of Maine, spend the winter as dormant cells in the upper layer of bottom sediment or the bottom nepheloid layer and germinate in ...