The Adaptive Importance of Toxin-Resistant Phenotypes in Calanoid Copepods

University Of Connecticut, Storrs CT

Investigators

Abstract

In previous work the Investigators have demonstrated genetic adaptation to the toxic dinoflagellate, Alexandrium sp., in one species of copepod, Acartia hudsonica. Recently, they discovered several classes of toxin-resistant phenotypes within A. hudsonica. This finding has profound implications for understanding predator-prey interactions in the oceans, well beyond the question of grazer adaptation to toxic algae. This project will follow-up on the discovery of toxin-resistant phenotypes in grazers by: 1) developing simple assays to distinguish phenotypes; 2) demonstrating that distinguished phenotypes are genetic; 3) determining if the resistant phenotypes are also related to resistance to starvation; 4) identifying linkages between toxin-resistant phenotypes, gut residence time and ingestion; and producing educational materials related to zooplankton, toxic algae, and evolution that align with the National Science Education Standards and Ocean Literacy Essential Principles and Fundamental Concepts. Achieving these objectives will likely lead to new research paths in ocean ecology and evolution. If resistant phenotypes are common among grazers, then prior results will need to be reconsidered and future studies must account for them. For example, currently there is no unifying explanation for the unpredictable appearance of selective grazing in many studies. Accounting for the frequency of resistant phenotypes in natural and laboratory populations could potentially solve this mystery. In addition, this study may very well explain mechanistically subjects as varied as distorted copepod sex ratios observed in the field and sloppy feeding observed in the laboratory. Finally, if grazing is important in the formation or termination of blooms, then resistant phenotypes could very well be central to the phenomenon. There is an immediate and urgent societal need to mitigate the effects of toxic phytoplankton blooms. Most of the work to date, however, is driven by bottom up thinking. The loss terms of toxic phytoplankton such as grazing have received much less attention. Local adaptation (resistance) of grazers to toxic algae is a feedback mechanism potentially leading to bloom control. On the other hand, grazer resistance may result in enhanced toxin transfer to top predators consumed by humans, and consequently lead to exacerbation of public health problems related to phytoplankton blooms. Therefore, it is imperative that we gain a full understanding of the generality of grazer resistance and of its nature in order to design and implement well-informed management strategies for toxic bloom mitigation. In addition, there is also an immediate and urgent need to improve the public's awareness of publicly funded science, evolution, and the world's oceans. To help fill this need, the results of this study will be organized by professional educators into prepared curricular materials that meet national standards. Further, the material will be made widely available via a website, CD's and workshops. This portion of the work will be presented at national meetings of scientists and secondary educators. In addition, the proposed work will also train a graduate student in zooplankton ecology, evolution and toxic algae research.