Microplastics in the diets of juvenile fish of Texas Coastal Bend bays

Microplastic ingestion by juvenile fish, which is highly context-dependent and poorly understood in situ, has not previously been examined in the critical nursery habitat of rural Texas Coastal Bend bays and estuaries. To provide a baseline quantification of microplastics ingested by juvenile fish in rural Texas Coastal Bend bays, juvenile fish belonging to seven taxonomic groups were collected throughout the year from Aransas Bay, Baffin Bay, Matagorda Bay, and San Antonio Bay in Texas, USA, and microplastics in their digestive tracts (n=669) were quantified by size, type, and color. Total microplastic ingestion was dependent on season (p=0.002), with the highest ingestion rate occurring in in November and December (0.7201 microplastics per fish) and did not differ significantly between bays (p=0.206). Fish condition indices calculated using whole and gutted weight were not significantly affected by microplastics ingestion (p=0.456 and p=0.854, respectively), nor were hepatosomatic indices calculated using whole and gutted weight (p=0.227 and p=0.460, respectively). However, spatial, temporal, and species-dependent variation in microplastic ingestion was highly dependent on microplastic color, type, and size. It is likely that there are factors influencing the degree to which juvenile fish ingest microplastics in rural Texas Coastal Bend bays other than merely what is present in the fish’s habitat. While these factors are thus far unknown, further exploration of the effect of microplastic ingestion by juvenile fish on their health is needed.