Microplastic ingestion of juvenile fish in Corpus Christi bay and upper Laguna Madre, Texas

Microplastic pollution and the negative effects of microplastics entering the marine food web has come into the focus of research in recent years. For early life stages of fish this is of particular concern due to their high energy demand, since sufficient food availability is necessary for fast growth and survival. However, not much is currently known about the extent of microplastic pollution in Corpus Christi Bay and the Upper Laguna Madre, and whether it presents a possible risk to juvenile fishes who may ingest microplastic together with similarly sized prey items. This study presents the first baseline information on microplastic pollution in Corpus Christi Bay and the Upper Laguna Madre, which are important nursery areas for fish species such as, Red Drum (Sciaenops ocellatus), Atlantic Croaker (Micropogonias undulatus) and Mullet (Mugil spp). Juvenile fish from Corpus Christi Bay and Upper Laguna Madre showed several unique differences and spatial patterns. Over 81% of the juveniles had one or more ingested pieces of suspected microplastics. Several species (Leiostomus xanthurus, Brevoortia spp. and Menidia spp.) had higher mean amounts of suspected microplastics in their digestive tracts, likely due to a difference in feeding guilds or prey preferences. In addition, juveniles collected from highly urbanized areas (Ingleside and Oso Bay) had larger or higher amounts of suspected microplastic in them. This thesis showed that microplastic fibers are regularly found in the digestive tracts of early juveniles of eight species of fish in the Corpus Christi Bay and Upper Laguna Madre area. Further studies are needed to evaluate potential health and survival concerns caused by the documented microplastic ingestion of early juvenile fish.