Bleached Elkhorn coral now under shade in Biscayne National Park

Shown here is a small colony of the threatened Elkhorn coral, Acropora palmata, that has become "bleached," that is, lost all its algal symbionts (also called zooxanthellae) because of the summer 2023 ocean-heat wave. The coral is attached to a cement block as part of the U.S. Geological Survey’s Coral Assessment Network (USGS-CAN) that provides data on coral-growth (calcification) rates throughout the western Atlantic. Data like these are collected to document seasonal and spatial patterns in coral growth that correlate with ocean conditions and are used to guide the management and restoration of coral species that have experienced population declines across the region, and pictured here is one of calcification stations located in Biscayne National Park. The shade structure could help to reduce light stress that is problematic when corals are in a bleached state (see https://www.usgs.gov/media/images/coral-shading-experiment-during-a-bleaching-event for more information).