Abstract
Harmful Algal Blooms (HABs) are sporadic or episodic proliferation of algal cell populations with toxic or noxious effects on the local environment. HABs arise through interactions between environmental conditions, population dynamics, and cell-level organismal characteristics. Better understanding of the primary factors and interaction mechanisms underlying most HABs would greatly enhance our abilities to predict the location, timing and severity of incipient HABs. Most harmful algae (and many other plankton) have dual-stage life cycles in which cells alternate between (i) pelagic vegetative stages, in which they actively grow and develop in the water column; and (ii) benthic resting stages, in which they lie dormant as cysts or spores in the sediments. Movement into and out of resting stages by swimming or buoyancy regulation has substantial impacts on timing, location and magnitude of algal blooms and other ecological dynamics. In Puget Sound, US, high-impact Harmful Algal Blooms of Heterosigma akashiwo and Alexandrium spp. are hypothesized to result from large-scale emergence from “hotspots” of benthic populations. The speaker and his research group have developed laboratory methods to quantify movement and cell division rates in Heterosigma and Alexandrium, associated with transitions between water column and sediments. Both swimming and cell division occur remarkably quickly (within hours) after previously dormant cells are exposed to growth-favoring conditions. Different strains of Heterosigma exhibit pronounced differences in survival, cell division and swimming rates. They hypothesize a tradeoff exists between resource allocation to these cellular functions. They have developed a modeling framework based on the hypothesized tradeoff that predicts bloom dynamics such as which water column conditions favor bloom formation, and which strain is likely to dominate a subsequent bloom.
About the speaker
Prof Daniel Grünbaum received his PhD in Ecology and Evolutionary Biology from Cornell University in 1992. He was research associate at the University of Washington from 1992 to 1993, and remain faculty there since then. He is currently Professor of Oceanography.
Prof Grünbaum’s research combines lab and field experiments with mathematical theory to answer fundamental questions about how marine ecosystems function. His research program seeks to establish quantitative relationships between short-term, small-scale processes, such as individual movement behaviors, and their long-term, large-scale population level effects, such as population fluxes and distributions.
Prof Grünbaum is an award winning educator. He has received the Science Education Advocate Award from the Washington State Leadership and Assistance for Science Education Reform (LASER).
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