Abstract:
Microplastics are tiny plastic particles less than 5 mm in size. They pose a major environmental
problem when contaminating ecosystems. This study was conducted to determine the presence
of microplastics in commercially harvested anchovies (Haalmassa) (Stolephorus commersonnii)
collected from Galle and Matara districts. Whole fish were digested using 68% nitric acid
digestion protocols and filtered through 20µm filter papers to isolate microplastics. Filter papers
with isolated microplastics were observed under a photomicroscope to identify the colour, shape,
and size. Identified microplastics were confirmed using Nile red staining techniques and polymer
types were identified using FTIR-ATR. All 40 samples tested positive for microplastics.
Microplastic abundance was significantly higher in the Galle sample (36.55±6.9 MPs/individual)
than in the Matara sample (26.80±10.6 MPs/individual). No relationship between morphometric
characters (weight and length) of fish and microplastic count inside the fish. Fragment was the
most dominant microplastic type (79.2%). Black was the most prominent colour in micro
fragments (64% and 53% in Galle and Matara, respectively) and blue was the most prominent
colour in microfibers (40% and 61% in Galle and Matara, respectively). All the microplastic films
were transparent. Red, orange, yellow, green and purple microplastics were also observed in
small quantities. Microplastics were categorized into three size classes based on length:small
(<0.5mm), medium (0.5–1.0 mm), and large (>1.0mm) with small being the most dominant size
class. According to FTIR-ART, microplastics found in anchovies included ethylene vinyl acetate,
ethylene butyl acrylate, high-density polyethylene, low-density polyethylene, medium-density
polyethylene and linear-density polyethylene. This study provides solid evidence that
commercially important anchovies are highly exposed to microplastic-contaminated
environment and further research is suggested to understand the health risk posed by consuming
whole anchovies.
