CHARACTERIZATION & QUANTIFICATION OF MICROPLASTICS AT CORAL GARDENS & ROCKY POINT, BELIZE

Microplastics are emerging contaminants found in water, sediment, air, and even animal tissues. Multiple studies have shown microplastics can be carriers of trace metals, contaminants that typically come from manufacturing or other urban sources. This study aims to quantify and characterize microplastics within Coral Gardens, which was a refugium for endangered Acropora cervicornis corals prior to a mass mortality event in 2023. Coral Gardens is off the coast of San Pedro, Belize, a town in Ambergris Caye that has many dive shops and fisheries. For comparison, another site in Ambergris Caye called Rocky Point was selected due to the substantial accumulation of macroplastics, the result of the reef crest intersecting with the island, creating a funnel for debris and trash onto the shore. Water samples were collected at both sites using 363 μm and 180 μm mesh plankton nets that were cast and dragged ~6 m lengths 20 times. 20 water samples of 50 mL each were also collected for trace metal analysis using inductively coupled plasma mass spectrometry. Sediment samples were collected by inserting test tubes into sediment approximately 5 cm deep. Sediment samples were sieved into four size fractions (4.75 mm, 2.00 mm, 212 μm, and 38 μm) prior to hydrogen peroxide digestion. In addition, dead coral from Coral Gardens was scraped to isolate algae, which were digested for organic matter using hydrogen peroxide. Each water, sediment, and algal sample was then density separated followed by microscopic analysis and microplastic categorization. Identified plastics were extracted when possible, and polymers were classified using Fourier transform infrared spectroscopy. Sediment samples from Rocky Point were found to have an average of 5 ± 4 microplastics per 27.5 cm³ following blank subtraction and will compare these results to those of Coral Gardens. We aim to better characterize the distribution of microplastics from shoreline sediment, offshore sand, and water in this coral reef environment.