Tropical reefs across the globe have suffered unprecedented losses of coral cover, with those in the Indo-Pacific following the same trajectory as the Caribbean. UNCW’s Dr. Joseph Pawlik asks: What will be the fate of former coral reef ecosystems decades from now? If the Caribbean is any guide, future reefs will be dominated by seaweeds, gorgonians, and sponges. Recent estimates of sponge pumping activities combined with discoveries related to carbon and nutrient cycling have revealed a feedback loop: seaweeds release dissolved organic matter (DOM) which is consumed by some sponges as a major portion of their diet, while sponges release inorganic nutrients that further enhance seaweed growth. Seaweeds and sponges will likely outcompete other benthos, including remaining corals. As limestone reefs degrade, sponges may be the only structural complexity for fishes and invertebrates. Reef fish and vertebrate communities will shift to reflect the available benthos, with increases in species that rely on seaweeds and sponges for food, including some angelfishes and hawksbill turtles.

Dr. Joseph Pawlik is the former Frank Hawkins Kenan Distinguished Professor of Marine Biology in the Department of Biology and Marine Biology at UNCW (2017-2025). He joined the Department of Biology and Marine Biology at UNCW in 1991, where he teaches undergraduate courses in Invertebrate Zoology and Biodiversity and has directed a research program involving undergrad, MS and PhD students. Dr. Pawlik worked at the US National Science Foundation (NSF) as a Program Officer in the Biological Oceanography Program for 2 years beginning 2003. He and his students and collaborators have authored over 170 publications, primarily on the ecology of sponges on Caribbean coral reefs. Dr. Pawlik travels around the world to SCUBA dive on tropical reefs where he documents the status of coral reef ecosystems with underwater video — you can see his videos on the YouTube channel “Pawlik Lab.”