Are migratory waterfowl vectors of seagrass pathogens?

Damian Michael Menning,David Hume Ward,Sandy Wyllie-Echeverria,Megan Cathleen Gravley,George Kevin Sage,Sandra Looman Talbot,Hunter Alexander Gravley

doi:10.1002/ece3.6039

Abstract

Migratory waterfowl vector plant seeds and other tissues, but little attention has focused on the potential of avian vectoring of plant pathogens. Extensive meadows of eelgrass (Zostera marina) in southwest Alaska support hundreds of thousands of waterfowl during fall migration and may be susceptible to plant pathogens. We recovered DNA of organisms pathogenic to eelgrass from environmental samples and in the cloacal contents of eight of nine waterfowl species that annually migrate along the Pacific coast of North America and Asia. Coupled with a signal of asymmetrical gene flow of eelgrass running counter to that expected from oceanic and coastal currents between Large Marine Ecosystems, this evidence suggests waterfowl are vectors of eelgrass pathogens.

Highlights

Seagrasses comprise the most widespread coastal ecosystems in the world (Green & Short, 2003)
There is an unexpectedly close genetic relationship between eelgrass meadows in Kinzarof and Izembek lagoons (Talbot et al, 2016), two lagoons separated by only 5 km of land, but at the least 510 km of coastline via the Alaska Coastal Current (ACC) that flows northward from the Gulf of Alaska Large Marine Ecosystem (GoA-LME) into the Eastern Bering Sea Large Marine Ecosystem (EBS-LME) at Unimak Pass (Figure 1)
This study reports the first instance in Alaska waters of pathogenic strains of Labyrinthula known to cause declines in seagrass meadows along the Atlantic coast of North America and Europe (Groner et al, 2014, 2016) and two other seagrass pathogens, Phytophthora gemini and Halophytophthora sp

Summary

| INTRODUCTION

Seagrasses comprise the most widespread coastal ecosystems in the world (Green & Short, 2003). There is an unexpectedly close genetic relationship between eelgrass meadows in Kinzarof and Izembek lagoons (Talbot et al, 2016), two lagoons separated by only 5 km of land, but at the least 510 km of coastline via the Alaska Coastal Current (ACC) that flows northward from the Gulf of Alaska Large Marine Ecosystem (GoA-LME) into the Eastern Bering Sea Large Marine Ecosystem (EBS-LME) at Unimak Pass (Figure 1). This finding suggests an additional dispersal mechanism—in particular, waterfowl (Talbot et al, 2016)—for eelgrass, and for pathogens on eelgrass. Prior to this study, no studies involving seagrass pathogens were ever conducted in this laboratory, or any other laboratories located in the same facility

| MATERIALS AND METHODS

Findings

| DISCUSSION