Microplastics are threatening the consumers at the base of the marine food web. Through biomagnification, interactions between lower trophic level organisms and microplastics have implications on the larger ecosystems. Our project studies microplastic load in environmental samples of copepods found in the Tampa Bay Estuary.
At each of the 7 stations, copepod samples were collected using a 200 µm mesh ring net tow (0.5 meter diameter) for 3 minutes. 1,000 copepods (when available) where picked from each of the samples and digested to release the contents of their guts. The samples were stained for 20 minutes in a 1mL:5mL Nile Red incubator and the stained plastic particles were visualized using epifluorescent microscopy, quantified, photographed, and sized using image analysis.
The number of microplastics that were consumed per 1,000 copepods ranged from 4 - 55, and diameter ranged from 1.8 µm to 351 µm. The data showed that there was no spatial or temporal trends, however, the encounter rates from this study where higher than the only other two field studies done on copepod ingestion of microplastic.
The results show that estuaries may be a site of increased microplastic ingestion because of the closer proximity to anthropogenic activities and semi-enclosed geography.