Ocean Sciences Meeting 2016
While attending the Ocean Sciences Meeting 2016 in New Orleans back in February, I was able to sit down over a coffee with some of the scientists currently researching coastal carbon cycling dynamics. I was able to hear about their field work tales, their current research, and where they see their field of research headed in the future. Needless to say, these meetings were definitely a highlight during my conference experience. Here I have included a few posters from those whom I spoke with during the conference, and whose research I found very interesting to hear about.
Brady O’Donnell (Ph.D. candidate, UC Davis)
The Bodega Marine Laboratory, situated in Bodega Bay, California, is the perfect location to study marine ecosystems. The surrounding seagrass beds of Zostera marina are the focus of Brady O’Donnell’s graduate research with the Hill Biogeochemistry Lab, where his team studies the ability of these seagrass beds to alter the seawater chemistry over relatively short time scales (daily, seasonally). In addition to this, Brady is studying the sediments associated with these seagrass beds and their ability to sequester both inorganic and organic carbon and compare this to non-seagrass sediments.
Using a combination of sediment cores and in-situ sensors at his sites, Brady has been able to answer some of these questions. Preliminary findings from one study site (Tomales Bay) suggest that finer sediments outside of the seagrass bed contain higher amounts of both organic matter and carbonate compared to the sediments within the bed, possibly due to grain size interactions.
In addition to continuing the data analysis for his four current seagrass bed sites (located in Tomales Bay and Bodega Harbour), Brady will be extending this research to additional sites in the near future in order to better understand the relationship between these factors.
Kristin Bulpett (M.Sc. candidate, U Massachusetts)
The U.S. Eastern Seaboard is home to some of the oldest colonial human settlements in North America, and it is no surprise that this has meant many years of alterations to the Boston Harbour, Neponset River and surrounding areas in New England. The Neponset River salt marsh is an area of interest for Kristin Bulpett’s graduate research particularly because of these alterations. Dredged materials from the Boston harbour and the Neponset River had been distributed over top of a coastal marsh, reducing most tidal inundation to the area and allowing the invasive Phragmites australis to outcompete native salt marsh grasses.
To reverse this, a restoration project was undertaken in 2005 which involved removing 35,700 cubic meters of the previously dumped material and relocating it to the northern area of the site, lowering the original marsh area by 1.5 feet to re-established tidal inundation. The restoration project has been considered a success due to the return of the native Spartina alterniflora salt marsh grass to the area and reduction of the invasive P. australis. However, the greenhouse gas dynamics from this process were not considered before or after the project. Kristin’s research (supervisor Dr. Robert Chen) looks at the success of the restoration project based on the carbon dioxide emissions.
A comparison of soil CO2 fluxes and percent organic carbon of both the restored and relocation areas was performed in order to assess the CO2 emissions from the restoration process. Though the restoration initially resulted in a significant release of previously sequestered soil carbon, the restoration of tidal inundation to the area lowered soil respiration rates to a point where net soil emissions from the project are estimated to be negative, overall. With this, Kristin concluded that the restoration project was indeed successful both ecologically as well as in terms of preventing CO2 emissions from the soil.
Future work would include establishing decay rates of soil carbon in coastal ecosystems that have previously been disturbed, either naturally or anthropogenically.
Rose Martin (Post Doctoral Fellow, ORISE)
Invasive species have been known to alter ecosystems at structural and functional levels, including biogeochemistry and trophic dynamics. On the eastern coast of the United States, Phragmites australis is a known invasive salt marsh grass species that appears to efficiently outcompete native species (Spartina patens, Juncus gerardii, Distichlis spicata) in the high marsh zone. These coastal wetlands are important greenhouse gas (GHG) sinks, and are considered a key ecosystem in mitigating the effects of climate change because of their ability to sequester carbon for long time scales (termed ‘Blue Carbon’). The shift from a native species-dominated marsh community to one that is dominated by P. australis has the potential to change the GHG fluxes, which is exactly what Rose Martin’s graduate research looked at in Narragansett Bay, Rhode Island.
By measuring soil gas fluxes (CO2, CH4, N2O) in situ between P. australis and native marsh species at three different marsh sites along a salinity gradient, Rose was able to compare fluxes between the vegetation types while addressing the confounding variable of salinity. The measurements were collected using static flux chambers and a Picarro G2508 cavity ring down spectroscopy (CRDS) analyzer during the summer growing season.
After analyzing and comparing the data, Rose found that while P. australis zones emitted more CH4 along all salinity gradients, they took up more CO2 than the native marsh species zones at mid (5-18 ppt) to high (18-30 ppt) salinity sites. The findings from Rose’s research highlight that there is indeed a difference between the native and invasive salt marsh species in relation to their GHG fluxes. Next steps for this line of research include monitoring GHG fluxes over annual and diel time scales in order to evaluate whether P. australis zone carbon sequestration rates compare with native marsh species.
This research was done under the supervision of Dr. Serena Moseman-Valtierra at the University of Rhode Island.
For more detail, download Rose’s poster, or read the published article.
Note: This is by no means an exhaustive list, this is just the tip of the iceberg of interesting research that is going on in the coastal realm of ocean sciences. Thank you to everyone for taking the time to meet with me during the Ocean Sciences Meeting, it was a pleasure.