LE3 .A278 2020

2020

Gibson, Glenys

Acadia University

Bachelor of Science

Honours

Biology

Biology

Microplastics are anthropogenic pollutants that are ubiquitous in marine environments. These minute plastic fragments are often defined as any plastic fragment <5mm, which enter the ocean directly or indirectly. Microplastics have been recorded in a variety of marine habitats such as in deep oceanic trenches, estuarine and coastal bays, and Arctic sea ice. They directly affect marine biota includingplanktonic a lgae, benthic invertebrates, fish, whales and birds. I used the Eastern mudsnail Tritia obsoleta to study tissue-level changes in digestive tubules following ingestion of microplastics or biodegradable microplastics. Fecundity of T. obsoleta was also analyzed by recording the number of viable embryos per egg capsule following plastic exposure. Plastics were collected from a local beach and ground into microplastic granules and fibers. Polylactic Acid (PLA) was also processed to determine if biodegradable plastics elicit similar effects on tissues as do non-bio plastics. Plastics were added to the biofilm diet of T. obsoleta in concentrations representative of those found in estuarine environments, including control (no plastic), low exposure (5 particles/kg sediment), and high exposure (150 particles/kg sediment), and also an extreme level (5,000 particles/kg), which more closely emulates concentrations used in other studies. After a one-month exposure, hepatopancreas histology was compared using PAS-AB, Gomori’s One-Step Trichrome, and Hematoxylin and Eosin, as well as scanning electron microscopy (SEM). Fecundity was decreased in the extreme groups relative to field samples. Additionally, significant differences were detected in the number of mature and immature hemocytes in snails exposed to high and extreme levels, and a significant decrease in height of digestive cells occurred at high and extreme concentrations. This study suggests that high concentrations of microplastics in surface sediments affect the structure of the digestive tubules, fecundity, and the number of hemocytes in this highly abundant estuarine species.

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https://scholar.acadiau.ca/islandora/object/theses:3368