Project Overview

Summary:

     Dr. John Valentine at Dauphin Island Sea Lab (DISL) was awarded an RFP-IV grant at $7,124,054 to conduct the RFP-IV project titled, “Alabama Center for Ecological Resilience (ACER)”.  The project consisted of 10 other institutions (Florida Atlantic University, Florida Gulf Coast University, Louisiana State University, Northeastern University, Rutgers University, Siena College, The University of Alabama, University of Florida, University of South Alabama, University of South Florida), 1 principal investigator (Valentine), 20 co-PIs (Drs. Susan Bell, Sarah Berke, Just Cebrian, Kelly Dorgan, J. Marcus Drymon, Kenneth Heck, Randall Hughes, Jeffrey Krause, Charles Martin, Tina Miller-Way, Behzad Mortazavi, Michael Parsons, Sean Powers, Alison Robertson, Patricia Sobecky, Kimberlee Thamatrakoln, Hidetoshi Urakawa, Alice Ortman); 6 PhD-level students (Cy Clemo, Kara Gadeken, Alexander Leynse, Nikaela Flournoy, Aaron Macy, Robyn Zerebecki); 16 master’s-level students (Clayton Bennett, Megan Feeney, Taylor Hancock, Samantha Blonder, Allison Bury, Adam Catasus, Liesl Cole, Stephen Hesterberg, Erin Kiskaddon, Michael Lindsey, Ryan Parker, Whitney Scheffel, Emily Seubert, Rachel Smolinski, Trey Spearman, Derek Tollette); 10 undergraduate students (Jesse Elmore, Andrea Boraski, Shelby Budai, Tess Caffray, Emma Fain, Megan Feeney, Erin Keller, Stephanie Smith, Kaitlyn Wagner, Erica Weldin); and several research technicians and administration personnel.

     The Alabama Center for Ecological Resilience (ACER) team will focus its investigations on critical living resources that underpin the extraordinary productivity of the northern Gulf of Mexico's (nGoM) "fertile crescent." We will use our existing in-depth understanding of the ecology of this economically vital region, along with an integrated program of sampling and experimentation to evaluate the role of biological diversity (ranging from genotype to ecosystem) in determining how the nGoM ecosystem can resist and recover from disturbance and stress produced by exposure to oil and dispersants.

The main objectives of the ACER are:

• To assess how coastal ecosystem structure, as measured by multiple estimates of biodiversity, and functioning (its provision of valuable processes and services) have been affected by differential exposure to Deepwater Horizon oiling.
• To determine how the biodiversity of coastal ecosystems can buffer resistance and recovery from oiling.
• To determine the conditions of disturbance that drive coastal ecosystems beyond their "tipping points," and prevent them from returning to their pre-disturbed states.

     In summary, the ACER team will build upon knowledge gained from previous multi-decadal investigations of the nGoM and will conduct new studies to clarify the role of biodiversity in buffering the harmful impacts of oiling and exposure to dispersants.

Ultimately, we expect this work to further our understanding of the extent to which biodiversity can ameliorate the stresses of oil pollution on the health, productivity, and services provided by coastal ecosystems.

     Our research will not only document impacts of oil and dispersants on valuable components of our coastal ecosystems, but it will shed light on the biodiversity effects and mechanisms influencing those impacts. In addition, it will provide essential data regarding the relative sensitivities of habitat-forming species to oiling that can be used in restoration efforts. Finally, this work will further our general understanding of the extent to which biodiversity can ameliorate the effects of natural and other anthropogenic stresses on coastal ecosystems and contribute to the provision of ecosystem services upon which human communities depend. 

Research Highlights

     Dr. Valentine’s research, which included 86 outreach products and activities, resulted in 16 peer-reviewed publications and 96 conference presentations to date and 74 datasets submitted to the GoMRI Information and Data Cooperative (GRIIDC), which are available to the public.  Significant outcomes of their research (all related to GoMRI Research Theme 3) are highlighted below. 

1. Vegetated marsh sediments had higher denitrification capacity than unvegetated sediments. This was likely due to plant-controlled resource availability (e.g., enhanced nitrification, higher organic carbon) rather than any changes in microbial community structure or function. Thus, vegetation loss and erosion from oil exposure may reduce wetland denitrification function (Hinshaw et al. 2017).
2. Field surveys 5 years post- Deepwater Horizon oil spill indicate that marsh plant biomass and microbial community composition had recovered, but marsh denitrification capacity was still reduced at oiled sites (Tatariw et al. 2018).
3. Lab experiments testing the impact of oiling history in sediments on response to re-oiling showed that dissimilatory nitrate reduction to ammonium (DNRA) potential rates increased with the addition of 100% water accommodated fraction (WAF) of oil in sediments from Dauphin Island (unoiled), while DNRA rates were similar across treatments in sediments from the Chandeleur Islands (oiled) and Dog River (unoiled). Nitrification and denitrification potential rates were similar across treatments at all sites (D. Tollette MS Thesis, Nitrogen Cycling sub-group, unpublished)
4. Field measurements from 7—8 years post-oiling showed that denitrification rates in black mangrove-dominated sediment were higher than those in smooth cordgrass-dominated sediment at a lightly oiled site, but there was no difference in rates between plant types at a moderately oiled site, where overall rates were lower. This muting of denitrification rates was accompanied by lower Shannon diversity, 16S abundance, extractable ammonium, and sediment bulk C and N in black mangrove sediments that were not observed at the lightly oiled site (Tatariw et al. in prep).
5. Wetland oiling effects were reduced in mixed versus single species mesocosm experiments for black mangroves, but we detected no benefit of mixed species assemblages or of smooth cordgrass genotypic diversity for smooth cordgrass. While mixed species wetlands are negatively impacted by oiling, they are no more susceptible than those dominated by a single foundation species (Hughes et al. 2018).
6. Although species-specific differences in bioturbation were observed between infauna taxa (i.e., brittle star versus polychaete), neither oil exposure (across levels tested) nor infauna diversity altered overall bioturbation rates. The latter suggests the dominance of brittle stars behavior in sediment mixing when included in the community (Dorgan et al. 2020).
7. Single nucleotide polymorphisms (SNPs) were developed and validated to measure genetic diversity in the eastern oyster (Crassostrea virginica and used to identity 2 distinct populations of oysters within the Gulf of Mexico (1. northeastern Gulf and north of Port Aransas, TX; 2. South of Port Aransas, TX). Further, these SNPs could differentiate between wild and hatchery stock oysters (Thongda et al. 2018).
8. Environmental factors such as salinity can have stronger effects on mediating oil and dispersant impacts on oyster survival than genetic diversity (Schrandt et al. 2018).
9. Oyster epibionts appear more resilient to oil exposure than oysters and oyster field sites that were visited in Louisiana still show depressed oyster densities that can be linked to the DWH oiling and response activities. (Oyster sub-group, PI Powers, unpublished).
   1. Using field surveys and stable isotope analysis of predator shark species across the northcentral Gulf coast and across seasons illustrated limited isotopic overlap among species in the fast turnover tissues tested. This suggests that predatory species are occupying more nuanced trophic role than previously assumed and also niches appeared to be fluid, shifting in response to potential changes in prey availability and environmental parameters (Seubert et al. 2019).
   2. Two decades of fisheries independent surveys of fishes and invertebrates in coastal AL and MS waters illustrated changes in the nekton community composition immediately following the Deepwater Horizon oil spill.  Survey results highlighted an increase in nekton abundance, coinciding with reduced diversity and alteration of community composition, suggesting dominance of few species. These findings are likely the combined consequences of both direct and indirect (e.g., behavioral changes, reduced fish predator and fishing pressure, and freshwater input) effects of oiling (Martin et al. 2020).
   3. During diver and remotely operated vehicle field surveys off the Alabama coast, researchers documented the first record of non-indigenous Indo-Pacific damselfish, Neopomacentrus cyanomos in the northern Gulf of Mexico on petroleum platforms and artificial reefs (Bennett et al. 2019).
   4. Surveys of from across-shelf transect south of Mobile Bay, AL during the fall when freshwater discharge is typically low, revealed that clear spatial differences in the physical, biogeochemical and plankton characteristics between inshore and 20-30 km offshore due to changes in the influence of freshwater flushing (Dzwonkowski et al. 2017).
   5. In laboratory experiments, the three coastal isolates (diatom, Skeletonema sp.; green algae, Tetraselmis sp., and dinoflagellate, Prorocentrum) all showed negative growth responses as the loading of petrocarbon (WAF, CEWAF, dispersant alone) increased. In monoculture experiments, the green algae appear to be the most resilient to the petrocarbon loading, with minimal growth effects up to 40 ppm. Moreover, growth rate decreases for the diatom and dinoflagellate isolates were muted when the starting biomass was 4-10-fold higher than initial tests, but dinoflagellate growth was highly sensitive to the type of petrocarbon loading, as CEWAF and dispersant were both effective at halting growth despite variable biomass. Additionally, in the CEWAF treatments, there was a shift in the size spectrum of phytoplankton-derived exopolymers toward smaller diameters. A shift to smaller and more abundant exopolymers may be an important indirect mechanism for phytoplankton to affect the timing of oil removal from the water column via particle aggregation and subsequent sedimentation (Phytoplankton sub-group, PIs Krause and Thamatrakoln, unpublished).
   6. In mixed cultures, blended with all three isolates (green algae, diatom, dinoflagellate), the diatom and dinoflagellate growth rates were less affected by petrocarbon loading than when growing in isolation. The green algae, which also showed resilience to growth rate declines from petrocarbon loading, displayed slower growth rates in the blended assemblage vs. the monoculture.  These data suggest 1) biodiversity allowed a majority of the cells (diatoms, dinoflagellates) to be more resilient to petrocarbon perturbation, but 2) the competition for resources among groups decreased the apparent resiliency capacity in the green algae. This suggests that while biodiversity may provide some increasing resiliency the ecological competition arising from that diversity may not lead to benefits among all species (Phytoplankton sub-group, PIs Krause and Thamatrakoln, unpublished).
   7. WAF exposure did not interfere with photosynthesis of benthic algae and only weakly influenced the hydrogen sulfide production but did have significant negative effects on oxygen penetration and oxygen concentrations in the water column. Most sediments exposed to WAF had an increased relative abundance of anaerobic microbial genera compared to control sediment correlating to decreases in oxygen penetration confirmed from microsensor profiling.  Additional analyses of the dissimilatory sulfite reductase beta-subunit (dsrB) operational taxonomic unit sequences correlated to the families desulfobacteraceae and desulfobulbaceae (containing known hydrocarbon degraders), which increased in relative abundance in sediments exposed to WAF (Benthic microbe sub-group – PIs Robertson, Parsons, and Urakawa, various manuscripts in prep).

 Proposal Abstract - RFP-IV PI John Valentine