1. 1. Mechanisms important to community structure under different ecological and spatial scales in estuarine and rocky intertidal communities

2. 2.Invasion, modification, and restoration dynamics of invasive dune and estuarine grasses

Our work in the rocky intertidal involves exploring the relative importance of local effects versus regional oceanography on community structure at the meta-ecosystem scale. We are using observations and experiments at 15 sites from Oregon to northern California to understand how variable nutrients and phytoplankton productivity produced by upwelling differences influence the interactions between two dominant community members (sessile invertebrates and macroalgae) that ultimately result in different community outcomes.

Sub-projects within the larger framework of this research include CRAZIE (Community Recovery Algal Zone Interaction Experiment), CAGIE (Comparative Approach: Geographic Interaction), ERK (Experimental Research with Kelp), and Surf ‘n Turf (Surfgrass and algal turf interactions). Collaborators on this research include Dr. Bruce Menge, Dr. Francis Chan, and Dr. Karina Nielsen. The work if funded by NSF.

We are exploring similar questions in estuaries to that in the rocky intertidal–we want to know the relative importance of local interactions versus regional oceanography on estuarine community structure at the meta-ecosystem scale. Estuaries on the west coast are highly influenced by ocean conditions especially in the most productive months of the spring and summer. We are using observations and experiments in 4 estuaries from Washington (Willapa Bay) to central Oregon (Netarts and Yaquina Bay) to southern Oregon (Coos Bay) to understand how variable nutrients and phytoplankton productivity produced by upwelling differences influence the productivity and species interactions between three dominant community members (eelgrass, macroalgae, and oysters).

Sub-projects within the larger framework of this research include seagrass/macroalgal interactions in multiple estuaries (Margot Hessing-Lewis thesis research with Dr. Bruce Menge and Dr. Steve Rumrill), oyster aquaculture and eelgrass  research in Willapa Bay (work with Dr. Brett Dumbauld and Dr. Jennifer Ruesink), and invasive eelgrass life history in Coos Bay (with Jeremy Henderson and Margot Hessing-Lewis). The work is funded by Western Regional Aquaculture Center and South Slough NERRS.

Our work also involves exploring how non-native species invade and modify their environment, and the mechanisms involved in restoration, under different contexts or gradients in physical conditions. In particular, we are studying dune grass invasions in Oregon and Washington to understand the mechanisms  involved in creating foredunes, how these modifications affect species diversity and rare endangered species, and  the potential for coastal protection against storms and tsunamis. Two separate congeners (Ammophila arenaria and A. breviligulata)  are simultaneously invading sandy beaches but they appear to have different effects on foredune morphology and species diversity (click here for a dune plant identification guide). For example, Ammophila has been implicated in the decline of a number of endangered plants and the federally listed Snowy plover. We are using observations, experiments, and modeling to understand how the three grass species and sand supply shape foredune morphology and ecology.

Sub-projects within the larger framework of this research include mechanisms of dune grass species interactions and sand accretion (Phoebe Zarnetske thesis research with Dr. Eric Seabloom), relationship between dune height and coastal protection  (work with Dr. Peter Ruggiero and graduate student Jeremy Mull), and exploration of ecosystem services and values (with NCEAS working group members). Outreach efforts have included a dune meeting in 2008: http://www.science.oregonstate.edu/~zarnetsp/PNW_Dunes_Website/index.html. Collaborators on this research include Dr. Eric Seabloom and Dr. Peter Ruggiero. The work if funded by Oregon Sea Grant and the EPA/USDA. 

We have also studied the invasion of estuarine grass Spartina anglica in Puget Sound, Washington. Though a series of experiments, our work has produced results that inform general theories on the ecology of invasions. In particular, we find 1) that biological resistance to the invasion from native species was weak compared to  the effects of physical conditions, 2) that invaders can create widely varying physical and biogeochemical modifications depending on the habitat it colonizes, 3) that removal of invaders is dependent on the removal regime and habitat type, and 4) that, once removed, restoration is likely highly context dependent with restoration occurring in some habitat but not others.   These results have led us to explore in more detail the ecological consequences of removing invaders; we predict that the legacy effects of highly modifying invaders can produce widely varying and alternative restoration outcomes. This work was in collaboration with Dr. Megan Dethier at University of Washington, Friday Harbor Labs.

Click here for a Spartina management booklet written by us for the Washington Sea Grant Program.