Date of Publication

7-31-2025

Document Type

Dissertation/Thesis

Degree Name

Bachelor of Science in Biology major in Medical Biology

Subject Categories

Biology

College

College of Science

Department/Unit

Biology

Thesis Advisor

Gliceria B. Ramos

Defense Panel Chair

Patricio Elvin L. Cantiller

Defense Panel Member

Marigold O. Uba
John Paul R. Domingo

Abstract (English)

Microplastics are small, solid, water-insoluble plastics with sizes ranging from 1.0 to 5.0 μm that can be irregularly or regularly shaped. They originate from minuscule or larger products that are broken down into smaller particles through physical, chemical, and biological processes. These plastic particles pose a significant threat to the environment and to the survival of living organisms within various ecosystems. The study investigated the impact of microplastics on the histology of the (1) gills, (2) cardiac muscles, and (3) epaxial muscles of Oreochromis niloticus, commonly named Nile tilapia. Sixty (60) Nile tilapia fingerlings were exposed to low-density polyethylene (LDPE) powder at concentrations of (1) 0.0 mg/L, (2) 50.0 mg/L, (3) 250.0 mg/L, and (4) 500 mg/L following acclimatization to laboratory conditions for seven days. The exposure period lasted for twenty-eight (28) days. The fish tissues were obtained, dissected, and processed by standard histological processing and then examined using a Nikon Digital Sight 1000 microscope. The results revealed that the microplastic LDPE caused (1) gill anomalies, including hyperplasia, telangiectasis, epithelial lifting, clubbing of tips, lamellar fusion, and edema. The (2) cardiac muscle tissues did not exhibit severe anomalies, as indicated by the minimal inter-bundle spacing of the muscle bundle arrangements and fiber orientation of the treatment groups, which were similar to those of the control group. For the (3) epaxial muscle tissues, there was a dose-dependent relationship between the concentration of MP and the presence of inflammatory cells in spaces between muscle bundles and muscle fiber dissociation, with higher concentrations leading to more severe tissue degeneration. This study showed several potential health risks associated with MP contamination in aquatic environments. The observed histological damage, particularly in the gills and epaxial muscles, highlights the vulnerability of aquatic organisms to MP exposure and necessitates immediate attention to plastic waste management and innovative solutions to reduce MP presence in aquatic ecosystems to safeguard the health of aquatic populations and potentially human health through the food chain.


Keywords: microplastics, Oreochromis niloticus, gills, cardiac muscles, epaxial muscles

Abstract Format

html

Language

English

Format

Electronic

Keywords

Microplastics; Nile tilapia; Gills

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Embargo Period

8-18-2025

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