Defense Date

8-3-2022

Document Type

Thesis

Degree Type

Master of Science

Degree Name

Marine Science

Second Degree Name

Marine Biology

First Advisor

David W. Kerstetter

Second Advisor

D. Abigail Renegar

Third Advisor

Christopher Sweetman

Keywords

Microplastic, forage fishes, pollution, southeast Florida, marine debris

Abstract

Microplastics threaten the health of numerous marine organisms at all trophic levels. Currently, the topic is well studied among larger predators such as marine birds, dolphins, pelagic fishes, and even herbivorous organisms such as manatees. However, knowledge of microplastics present in organisms at lower trophic levels is poorly understood. The aim of this study was to assess the presence of microplastics in lower trophic level forage fishes. To gain a clear depiction of microplastics in the forage fishes of South Florida, four locations were sampled. These locations were classified into two categories, urban (Port Everglades and Northern Biscayne Bay) and non-urban (Islamorada and Marathon, in the Florida Keys). Five species were sampled: Striped Mullet, Scaled Sardine, Needlefish, Pinfish, and Irish Mojarra. Every sampled fish except one (n= 248) had microplastics within their systems, with a total of 2,126 pieces found. There was no significant difference in microplastics concentration among forage fish species. However, location had a significant effect on the frequency of microplastics found within the sampled fishes, with Northern Biscayne Bay being greater compared to the other three sample locations. There was no significant difference in microplastic frequency amongst the three feeding habits within the five sampled species. However, as Redfin Needlefish and Pinfish matured, an increase in microplastic frequency was observed. With a frequency of 99.6% of microplastic contamination within the sampled fishes, significant conservation efforts should be warranted.

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