Climate-linked Mechanisms Driving Spatial and Temporal Variation in Eelgrass (Zostera marina L.) Growth and Assemblage Structure in Pacific Northwest Estuaries, U.S.A.

Abstract

ABSTRACT Thom, R.; Southard, S., and Borde, A., 2014. Climate-linked mechanisms driving spatial and temporal variations in eelgrass (Zostera marina L.) growth and assemblage structure in Pacific Northwest estuaries, USA. Using laboratory experiments on temperature and leaf metabolism, and field data sets from Washington, between 1991 and 2013, we developed lines of evidence showing that variations in water temperature, mean sea level, and desiccation stress appear to drive spatial and temporal variations in eelgrass (Zostera marina). Variations in the Oceanic Nino Index (ONI) and mean sea level (MSL), especially during the strong 1997–2001 El Nino-La Nina event, corresponded with variations in leaf growth rate of an intertidal population. Field studies suggested that this variation was associated with both desiccation period and temperature. Subtidal eelgrass shoot density recorded annually over a 10-year period was lowest during the warm and cool extremes of sea surface temperature. These periods corresp...