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Cyst-forming dinoflagellates in a warming climate
Michael L Brosnahan1, Alexis D Fischer2, Cary B Lopez3
1Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA USA.
Harmful Algae
|February 15, 2020
Summary
Harmful algal bloom (HAB) species survive between blooms as resting cysts. Temperature seasonality influences their germination and bloom timing, potentially leading to more localized and earlier HABs in shallow waters.
Area of Science:
- Marine biology
- Phycology
- Ecology
Background:
- Harmful algal bloom (HAB) species persist between blooms via benthic resting stages, crucial for species survival and bloom initiation.
- Understanding the physiology of these benthic stages, particularly dinoflagellate resting cysts, is vital for predicting responses to climate warming.
- Cyst germination depends on favorable temperature, oxygen, and release from dormancy, a mechanism preventing germination under ideal conditions.
Purpose of the Study:
- To review and present evidence of temperature-mediated control of dormancy duration and quiescence in HAB dinoflagellates Alexandrium catenella and Pyrodinium bahamense.
- To explore the interaction of temperature-based dormancy mechanisms with climate change using a model for A. catenella.
- To investigate the role of new cyst formation in bloom termination and its implications for HAB duration.
Main Methods:
- Review of existing evidence on temperature-mediated dormancy and quiescence in A. catenella and P. bahamense.
- Development and parameterization of a simple model using experimental results from A. catenella to simulate climate interactions.
- Analysis of recent field investigations on A. catenella, focusing on new cyst formation and bloom termination.
Main Results:
- Seasonal temperature cycles synchronize cyst dormancy release; A. catenella shows greater tolerance to warming in habitats with higher temperature seasonality.
- Warming may lead to more localized HABs starting earlier in shallow, seasonally variable habitats compared to deep offshore ones.
- New cyst formation, triggered by high cell concentrations, acts as a bloom termination factor, limiting bloom intensification.
Conclusions:
- Temperature seasonality plays a critical role in regulating the timing and localization of HABs, influencing species distribution under climate change.
- Shallow, inshore habitats with greater temperature variability may favor persistent HABs, while warming's impact is limited in areas with narrow germination windows.
- Cyst bed quiescence and the drive for new cyst formation are key factors determining the duration and intensity of HAB risk periods.
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