Overview This project outlined the use of meiofauna from the Gulf continental shelf to study the environmental impact of the Deepwater Horizon oil spill on the ocean floor. The project united experts from 2 universities and will continue the meiofaunal surveys of PI Landers and colleagues that began in 2007. Dr. Landers and colleagues thus far have 4 years of meiofauna abundance data from 2007-2010 and also have archived kinorhynchs from Gulf sediment samples for taxonomic study. Drs. Landers (PI) and Yu (Co-PI) received GoMRI rapid response funding for 2011 and were in a position to continue this research with a focused effort on meiofauna abundance, pollution exposure, and identification of meiofaunal animals.
Sediment cores were collected from multiple locations across the northern Gulf of Mexico, in conjunction with NOAA. Samples were collected for:
- Meiofauna counting and identification
- Hydrocarbon analysis
- Granulometry analysis
- Identification of specific animals (copepods, nematodes and minor phyla) that may best show the presence or absence of an environmental effect due to contamination.
Additionally, CTD data was collected by NOAA at each sample site. Statistical analysis of data, photography of select specimens, and GIS mapping coincided with the meiofauna ID. The results will integrate data from chemical, physical, and biotic sampling and will provide an important view into the effects of the oil spill. Ultimately, this research will provide a better understanding of the effects of pollutants on benthic environments (and the food web that relies upon the benthos), and how the benthos may influence the degradation of the pollutants. The project addressed theme 3, (Environmental effects of the petroleum/dispersant on the sea floor . . .) through a study of the animals that live in the sea floor in relation to their pollution exposure and the characteristics of their microscopic ecosystem.
Questions to be addressed:
- Has there been a change in the meiofaunal community structure and diversity in oiled sites?
- Does the species composition of the copepod, nematode and minor phyla community show changes over time and with proximity to the DHOS?
- Can any such changes be used to interpret or predict oil remediation or impact in the future?
- Is there evidence of impact or recovery from the DHOS when comparing meiofauna from 2007-2015?
Dr. Landers’ research resulted in 7 peer-reviewed publications and 13 datasets being submitting to the GoMRI Information and Data Cooperative (GRIIDC), which are/will be available to the public. Dr. Landers engaged 10 students over the award period. Significant outcomes of their research according to GoMRI Research Theme are highlighted below.
- Results and scientific highlights from 2012 sediment analysis, collected with a Shipek® grab and a box corer:
- Sediment chemistry results indicated very low levels of total PAHs (<1ppm) along the 100M-200M isobath. This suggests that the sediment at this depth, along the edge of the continental shelf, either received little oiling in 2010 or such oiling was not detectable in 2012 sediment.
- Sediment chemistry results indicate a sharp transition with respect to trace metal concentrations, near site 86 (at approximately 88.55 degrees west). High levels of Cu, Li, Ni, Pb, V, and Zn, among others, correlate with aluminum levels west of site 86, indicating that these metals are high as a result of silicate binding and river outflow. Higher levels of strontium and low aluminum east of site 86 indicate less influence of river runoff and the presence of carbonate, plankton-derived sediment.
- Nematode and copepod densities appear to be influenced by sediment granulometry.
- Over 28 genera of nematodes were identified as new records for the Gulf of Mexico from the 2012 collections.
- Two new species of kinorhynchs were discovered and formally described using animals collected in 2012 as well as archived animals from our previous collections.
- Results and scientific highlights from 2013-2014 sediment analysis, collected with a multicorer:
- Sediment chemistry results indicate low levels of PAHs (<2 ppm  and <1ppm  for EPA priority pollutants) along the 100M-200M isobath. This suggests that the sediment at this depth, along the edge of the continental shelf, either received little oiling in 2010 or such oiling was not detectable in 2013 and 2014 sediment.
- Sediment chemistry results indicated a sharp transition with respect to trace metal concentrations along the north central continental shelf, as was detected in 2012 sediment. High levels of aluminum and associated metals dominated the sediment in the west (LA) as a result of silicate binding and river outflow. High levels of strontium and calcium in the east (FL) indicate less influence of river runoff and the presence of carbonate, plankton-derived sediment.
- Nematode and kinorhynch densities appear to be influenced by sediment granulometry.
- Over 31 species of kinorhynchs were identified in the 2013-14Gulf samples. Three more new species were formally described by Landers and his colleagues. There are still > 20 species being investigated that are not identifiable in the literature and are being treated as new discoveries. The publication of these species descriptions will take time over the next few years.
- Communities of nematodes (roundworms) and kinorhynchs (mud dragons) are influenced by sediment type, as those communities are different in Louisiana shelf sediments when compared with Florida shelf sediments. These communities are influenced by abundance as well, as those collections with higher animal densities clustered with each other statistically, compared to sites with lower densities.
- Analysis of the 2013-2014 nematode communities, collected with a multicorer, resulted in the identification of 151 nematode genera from 32 families.
- Future journal submissions are planned to name new kinorhynch species and to report nematode and kinorhynch community structures.