Estuaries are also plagued with HABs, usually dominated by dinoflagellates rather than blue-green algae. Dinoflagellates are armored with plates, and some contain intracellular toxins (e.g., causing lethal red tides) causing similar ecological impacts as blue-green algae. Also similar to blue-green algae, dinoflagellates are negatively affected by circulation. Solar-powered circulators were deployed in an estuarial lake in San Francisco Bay in 2003, and have eliminated all fish kills and allowed a near-extinct oyster to make a comeback in this recreational lake. Solar-powered circulators have the potential to clean up and reverse huge environmental problems in estuaries, including very large bay ecosystems.