We address scientific questions about community change resulting from the Deepwater Horizon oil spill and subsequent remediation efforts. We are examining standing stocks, growth, and elemental flow in dominant plants, microbes, common meiofaunal and macro-invertebrate consumers, and soil to test hypotheses about how salt-marsh ecosystems function under different stressors. Field efforts were supported by a NSF Rapid Grant with the explicit understanding that additional monies will be sought to complete analyses. This proposal supports these analyses.
This exceptionally large oil spill and remediation efforts are landmark opportunities to learn about the short- and long-term stressors on ecosystems. Stressors have indirect effects because, as they begin to degrade, these compounds enter food webs via primary consumers such as suspension-feeding oysters, deposit-feeding bivalves, and grazing gastropods. Stressors, such as those arising from HC spills, can have dramatic, visible, and immediate direct impacts on coastal ecosystems due to both physical and toxic effects on organisms. A suite of experienced field investigators completed one of three sample collection trips under a NSF Rapid program (DEB and BO; start 15July 2010) use these funds to analyze hydrocarbon (HC) composition and to conduct other analytical activities, as well as salary support for technical staff and students.
Thirty-two salt marshes in three estuaries were sampled in May 2010 before oil contaminated these marshes. These sites and others will be revisited in Sept. 2010 and May 2011. The results of these field campaigns will measure short-term (3 mo.) and longer-term (11 mo.) exposure to stressors, thus providing a basis for further measurements over many years under additional funding instruments.
Field data and samples collected include:
(a) Below- and aboveground biomass of the dominant emergent macrophyte(s),
(b) Mollusks and ground- and plant-dwelling insects and spiders and
We expect our samples to reveal:
(a) Changes in nitrogen fixation rates
(b) Species turnover in parasitic and symbiotic ‘terrestrial’ arthropods
(c) Changes in community composition of microbes (Bacteria, Archaea, and microeukaryotes), foraminifera, and phytoplankton (dinoflagellates)
(d) Estimates of habitat fragmentation
(e) Anaerobic soil conditions and soil metabolism
(f) Changes in sulfur accumulation and stable isotope signatures
(g) Changes in live history traits (growth rate, recruitment, mortality, reproduction) of the oyster Crassostrea virginica and other shelled, co-occurring mollusks that are primary consumers
These primary consumers, in turn, serve as food sources for higher trophic levels including humans. We will use this data to test various hypotheses about the effects of chronic and long-term stressors (oil, toxins, dispersant, and nutrients) on salt marsh ecosystems. Ultimately, incorporation of our data into Cascading Extinction on Graphs (CEG) models of community dynamics can predict the indirect long-term consequences of these stressors to salt-marshes.