Research Spotlight: Ants on Assateague

Close-up of ants in the dunes on Assateague Island during the study.

Salisbury University

Background

Ants are unique insects that play many important roles in the food web. They help disperse seeds, decompose dead organisms, and are consumed by predators. Ants are eusocial, meaning they live together in a colony with one single female producing all the colony’s offspring.

There are approximately 1,000 recorded species of ants in North America and only 124 of these have been found in Maryland. As global temperatures rise, populations will be susceptible to change. In the southeastern United States, rising temperatures are predicted to cause a decrease in ant biodiversity, while in northern regions, biodiversity may increase as species expand their range. Little is known about ants on Assateague Island, so researchers from Salisbury University performed a study on ant biodiversity and food preferences in 2019.

Researchers used aspirators to collect ants for the second half of the study looking closer at food preferences.

Salisbury University

Ant Biodiversity and Food Preferences

For the first half of the study, researchers used pitfall traps to collect ant specimens, allowing them to determine which ant species are present in Assateague Island’s maritime forests and dunes. Twenty-four species were collected from maritime forest habitat and 14 species from the dunes. The forest has a higher species richness, showing that it can host a higher variety of ant species. Life on the dunes is much harder due to the harsh conditions of sunlight and ever-changing sand, so only hardy species adapted to survive out there can call the dunes home.

For the second half of the study, the researchers collected both ants and possible ant food sources in Assateague’s forests and dunes. These samples underwent stable isotope analyses, and the amount of nitrogen and carbon were calculated for each. Interestingly, the ants within the dunes were significantly more carbon-enriched than those in the forests, suggesting ant species within the dunes, and close to the Atlantic Ocean, may consume some marine species. Marine food resources are often more enriched in 13C and ants may incorporate marine food resources into their diet when available.

Because of the specimens recorded in this study, 9 new species were added to the park’s Species List, bringing the number of known ant species present at Assateague Island National Seashore to 38. This number will likely change through time as new species are recorded on the island during future inventories.

For more information about this study and access to a more detailed NPS Resource Brief, please visit: https://irma.nps.gov/DataStore/Reference/Profile/2296775

A photo of the two habitat types surveyed during this study: dunes and maritime forests (in the distance).

Salisbury University

Written by Abby Hastings, Student Conservation Association (SCA) Intern
Park Contact: Lindsay Ries, Biologist