AME 25:99-102 (2001)  -  doi:10.3354/ame025099

ABSTRACT: Bleaching manifests itself as a loss of symbiotic dinoflagellates (zooxanthellae) and/or chlorophyll from a variety of symbiotic hosts, including corals and sea anemones. Bleaching is known to result from a range of environmental stresses, the most significant of which is elevated temperature; how these stresses elicit a bleaching response is currently the focus of intense research. One consequence of environmental stress that has yet to be considered is viral attack. Here, we have isolated a transferable infectious agent believed to be a virus, from zooxanthellae of the temperate sea anemone Anemonia viridis. The infectious agent is induced by elevated temperature. Once induced, the filterable agent can be further propagated without heat induction, thus fulfilling Koch¹s postulates. We propose that zooxanthellae harbor a latent viral infection that is induced by exposure to elevated temperatures. If such a mechanism also operates in the zooxanthellae harbored by reef corals, and these viruses kill the symbionts, then this could contribute to temperature-induced bleaching.

KEY WORDS: Viruses · Anemones · Coral bleaching · Zooxanthellae · Latent infection