In this project, PI Angelini worked with a team of graduate and undergraduate students as well as local and international collaborators to conduct research focused on the relative roles of secondary foundation species, and the diverse and abundant communities they facilitate, in controlling ecosystem functioning and resilience to global change.

The team undertook a series of manipulative field experiments and regional-scale surveys to explore the effects of ribbed mussels, a secondary foundation species, and the invertebrate communities they facilitate in controlling the resistance and recovery of intertidal salt marshes to drought. In the second year of the project, our scope of work further expanded to investigate the effects of secondary foundation species in mediating biodiversity, ecosystem functioning and resilience through one global meta-analysis (Thomsen et al. 2018, Nature Ecology and Evolution) and a second review paper (Gribben et al. in press, Oceanography and Marine Biology Annual Reviews). In our experimental work, we discovered that mussels, by locally enhancing soil moisture, protect salt marsh vegetation from dying back during severe droughts and, in supporting small vegetation patches, enable the marsh to recover quickly, thus functioning as keystone mutualists (Angeini et al. 2016, Nature Communications).

We then expanded this work to explore whether the positive effects of mussels could be harnessed to improve salt marsh restoration success and found that mussels increase marsh grass growth, enhance its resilience to intensive disturbance (Derksen-Hooijberg et al. 2018, Journal of Applied Ecology) and protect it from drought by buffering soil acidification and metal toxicity stress (Derksen-Hooijberg et al. in press). However, additional experiments revealed that juvenile fiddler crabs that are attracted to the soft pseudofeces that accumulates around mussels aggregations disrupt the positive effects of mussels on cordgrass and thus mediate the strength of benefits the plants derive from these bivalves (Derksen-Hooijberg et al. 2018, Ecosystems). Additional studies inspired by these results have further revealed that the spatial configuration of mussel patches in the marsh, mediated through the effects of patch size in controlling the relative availability of mussel patch edge: mussel patch interior habitat, powerfully controls their effects on ecosystem properties (Crotty et al. 2018, Ecology Letters) and that tidal creek morphology and predation pressure act together to control mussel spatial configuration across SE US marshes (Crotty et al. in preparation for PNAS).

Through an experiment that engaged two courses and institutions (Angleini's Coastal Systems class at UF and Mark Bertness' Marine Ecology class from Brown University), we have also shown that mussels, through their filter feeding activities, are driving dramatic increases in concentrations of polychlorinated biphenyls in both the sediment and primary consumers in this coastal habitat (Prince et al. in preparation for Nature).Through the support of the NSF REU program, another undergraduate student was able to conduct independent research that aligned with our project goals this past summer, work that is exposing how mussels may be mediating carbon dynamics across marsh landscapes. Finally, research focused on the role of Spanish moss, a vascular epiphyte that functions as a secondary foundation species across coastal forests in the SE US, led by a Dutch graduate student hosted in the Angelini lab ran in parallel to this NSF project, work that is producing additional insights about the importance of this epiphyte in controlling biodiversity and Nitrogen cycling in the region (Borst et al. in preparation. van Elzden et al. in preparation). 

Through our primary experiments, spin-off studies and review papers, this NSF-funded project has provided direct or indirect support for 7 graduate students (S Crotty, K Prince, M Derksen-Hooijberg, J Hoogveld, A Borst, E van Elzden, S Sharp), 5 undergraduates (H Fischman, A Cetta, E Johnson, K Cronk, T Pettengill), and sustained a productive international collaboration between the Angelini lab and the van der Heide and Lamers' labs from Radboud University in Nijmegen, The Netherlands and the University of Groningen. Our research has been presented at numerous international and national conferences, generated 11 peer-reviewed publications (and counting) and has also been shared with the Georiga Department of Natural Resources and Sapelo Island/Hog Hammock Community through local presentations. Results have also been integrated into Angelini's three courses at the University of Florida: Coastal Systems, Ecological Engineering and Environmental Planning and Design. Finally, we have involved public school teachers involved in the LTER Schoolyard program for the past three years in the proposed research activities. Thus our project findings have been activity disseminated to multiple audiences and are being used to motivate future work at the Georgia Coastal Ecosystem LTER. 

Last Modified: 12/31/2018
Modified by: Christine Angelini