Project: RAPID: Effects of the 2023-24 El Nino on Fish Disease and Population Dynamics in the Galapagos Islands

Disease is a growing threat facing wild animals in a world increasingly dominated by humans. Marine fish diseases are poorly understood but have increased in recent decades in connection with ocean warming. In the Galapagos Islands of Ecuador, extreme warm waters have led to ulcerative skin disease in several different species of fish. An outbreak of this skin disease is underway in association with a strong El Niño event. This project addresses the growing threat of wildlife disease and the current outbreak of skin disease in fish of the Galapagos Islands by determining what proportion of different species are affected and by examining infected fish from the wild. Infected fish are being assessed for microbes that might cause the disease, and ocean temperature are being monitored along with other factors that may foster skin disease. Isolated microbes are being used in lab tests to see if they cause the same disease seen in the field in order to confirm the cause of this ulcerative skin disease.

This project includes training for students in the US and in Ecuador and development of a virtual teaching module for high school students in English and Spanish. The research team is working closely with the Galapagos National Park to address the threat of fish disease and associated population declines caused by the 2023-24 El Niño event, and to help modify fisheries policy to reflect species' vulnerability. Through public symposia and online learning materials, this work serves as a platform for teaching and engaging students of all ages and industry stakeholders on issues of climate change and wildlife disease. The research advances understanding of how and why these ulcerative skin disease outbreaks occur in the Galapagos, which is very important for marine reserve and fisheries management and can have far-reaching impacts for understanding and addressing diseases in wild fish as well as in aquaculture and aquarium industries.

Climate change increases the frequency and severity of marine heatwaves, such as those experienced in the Tropical Eastern Pacific Ocean during extreme El Niño events. An extreme El Niño that began in summer 2023 and has facilitated an outbreak of an ulcerative skin disease in several species of marine fish. This project: 1) establishes the extent of ulcerative skin disease, species affected, demographic, environmental, and ecological correlates, and timing of disease progression relative to the development of the El Niño event; 2) determines the putative pathogen(s) responsible for ulcerative skin disease through histological and genetic analyses, pathogen cultures, and laboratory challenge trials; and 3) examines the effects of the El Niño event on fish populations by building a database of morpho-ecological traits for 165 species of reef fish and using multivariate ordination analysis to test the ability of these traits to predict El Niño-associated declines relative to an 8-year database of fish populations at 16 sites across the archipelago.

The results advance understanding of a widespread emerging fish disease and reef fish populations dynamics in a warming ocean. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.