Cnidarian (e.g., coral) symbioses under climate change: can obligatory symbioses exhibiting symbiotic fidelity survive the Anthropocene era

Mutualistic symbioses can enable organisms to extend their range of inhabitable habitats.  As such, when faced with the Anthropocene era, symbiosis may be the ticket to survival.  Conversely, since symbiosis relies on two or more partners, how these partners cope with climate change may make a symbiosis prone to perish.  In this talk, I posit that a symbiosis’ chances for success during the Anthropocene era relies on two characteristics of a symbiosis and the interplay between them. 1. Whether, for at least one of the symbiotic partners, the symbiosis is obligatory, i.e., the partner must be in symbiosis to survive, or whether the association is facultative. 2. Whether a symbiosis can only form with a subset of partners, i.e. fidelity, either context dependent or absolute.  Conversely, flexibility may exist, enabling different partner combinations.  I will present data synthesis on symbioses between cnidarians (e.g., hard corals, octocorals, sea anemone) and their myriad of symbiotic partners such as dinoflagellate algae (family Symbiodiniaceae), crabs, and fishes.  The position of cnidarian symbioses in the symbiotic landscape of obligatory vs. facultative, and fidelity vs. flexibility, may dictate the outcome for the symbioses in light of continuation of climate change.  For example, an obligate symbiosis with partner fidelity may need to rely on the robustness of the existing symbiosis for its survival.  Since many cnidarian symbioses are obligate and exhibit high fidelity, coral reefs may face mortality of certain symbioses, leading to a loss of biodiversity on coral reefs, as the Anthropocene era continues.