Sample Collection
Net Tows
Twice a year (January and July), members of the project tow a neuston net for 15 minutes at 7 sites around Tampa Bay. These net tows help collect microplastic samples that can be used for analysis later.
Historically, we have analyzed the copepods that were collected to determine microplastic quantities in their gut systems.
Necropsies
Provided by the FWC marine mammal pathobiology lab, samples from necropsies done on manatees recovered from Tampa Bay are given to the project. Samples come from five parts of the gastrointestinal tract of the manatee in duplicates.
While this data is no longer being collected, we are open to working with the pathobiology lab again in the future.
High Frequency Sampling
Minimal testing has been done within coastal estuarine systems, so the purpose of this study is to quantify microplastics in these areas for a better understanding of their treat to the ecosystem. The goal of this study was to observe the variation of microplastic concentrations at a single location, and surface bucket samples were collected from a pier near the Galbraith Marine Science Laboratory at Eckerd College at bi-hourly intervals during the daylight hours. These samples were collected for two consecutive days in each of three consecutive weeks in January 2019, June 2019, and January 2020. For each collection period, water depth and wind speed were recorded. The samples were then filtered through stacked sieves, rinsed into a beaker, and resettled with Milli-Q water.
After 48 hours, the samples were poured into a new beaker and the material that had settled at the bottom was discarded. The remaining supernatant was dyed with Nile Red and then transferred to black polycarbonate filters. Image analysis was used to quantify the particles, and the results showed how microplastic concentrations can vary based on tidal cycle and environmental conditions.
Instruments
Microscopic imaging is used with cyan-blue light to identify microplastics through an orange filter.
Flow cam photography and data collection is used for identification of particles through a fluorescence trigger.
Sediment Sampling:
As part of this project, sediment sampling takes place at 7 different stations in Tampa Bay, including Boca Ciega Bay, Egmont Key, Skyway Bridge, Hillsborough Bay, Old Tampa Bay, MacDill Air Force Base, and Pinellas Park. These are the same 7 stations that the copepod and seagrass samples were collected.
The samples were collected to determine the concentration of microplastics in marine sediments around Tampa Bay since there is little previously known about the deposition of microplastics in sediments.
Discrete Sampling:
Twice a year, samples from 7 stations throughout Tampa Bay were collected, quantified, and analyzed. The samples were collected from the surface using 20 liter buckets and filtered through 12µm and 20µm sieves and stained with a Nile Red solution. They were then filtered onto a black polycarbonate filter. We were able to easily identify microplastics larger than 100µm because they glowed when stained, however, microplastics smaller than 100µm were more difficult to identify due to their small size and less efficient staining.
Precautions were taken to prevent background contamination, however, blank replicates were collected regularly and the data was corrected for the minor contamination. The data was analyzed to identify temporal and spatial trends, as well as variability in the microplastic distribution.
Our research is the first of its kind in the area, and we continue to quantify microplastics in Tampa Bay.