Year

2025

Season

Spring

Paper Type

Master's Thesis

College

College of Arts and Sciences

Degree Name

Master of Science in Biology (MS)

Department

Biology

NACO controlled Corporate Body

University of North Florida. Department of Biology

Committee Chairperson

Dr. John Hatle

Second Advisor

Dr. Adam Rosenblatt

Third Advisor

Dr. Anthony Rossi

Department Chair

Dr. James Gelsleichter

College Dean

Gelsleichter, James

Abstract

The urban heat island (UHI) effect makes urban areas hotter than rural areas. Urban areas, and the extreme heat that comes with them, are becoming more common worldwide. If UHIs lead to changes in arthropod community diversity, then ecosystem structure and services could be disrupted. Previous UHI studies have investigated heat impacts on arthropod ecology, but many focus on one species while studies that consider thermal diversity within a single urban area have been limited. In Jacksonville, Florida, areas that are 12°C hotter than the coolest areas are considered local UHIs. The goal of this research is to investigate how the UHI effect is impacting arthropod populations and communities in Jacksonville. For the population-focused research, Eastern lubber grasshoppers (Romalea microptera) were collected from local heat island and non-heat island sites and reared them in the lab under both high temperature and control conditions. Growth, feeding, and reproductive rates of the grasshoppers were compared across treatments. For the community-focused research, arthropod communities were sampled from local heat island and non-heat island sites around Jacksonville and diversity was compared across sites.

There were significant differences in grasshopper growth rate, feeding rate and reproduction rate between high heat and control treatments in the lab, but statistically significant differences due to grasshopper origin were minimal. There was no statistically significant difference in invertebrate diversity of local heat island or non-heat island sites, but there was a consistent trend towards higher diversity at non-heat island sites. These results suggest the UHI effects in Jacksonville are not yet strongly limiting to arthropod species present in the area, and that UHI effects have not yet caused divergence in thermal tolerance at the population level. Deeper understanding of UHI effects on arthropods requires research that incorporates longer time frames and larger sample sizes.

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