Adaptations by Zostera marina Dominated Seagrass Meadows in Response to Water Quality and Climate Forcing

Erin Shields,David Parrish,Kenneth Moore

doi:10.3390/d10040125

Abstract

Global assessments of seagrass declines have documented accelerating rates of loss due to anthropogenic sediment and nutrient loadings, resulting in poor water quality. More recently, global temperature increases have emerged as additional major stressors. Seagrass changes in the Chesapeake Bay, USA provide important examples of not only the effects of human disturbance and climate forcing on seagrass loss, but also meadow recovery and resiliency. In the York River sub-tributary of the Chesapeake Bay, the meadows have been monitored intensively using annual aerial imagery, monthly transect surveys, and continuous water quality measurements. Here, Zostera marina has been demonstrating a shift in its historical growth patterns, with its biomass peaking earlier in the growing season and summer declines beginning earlier. We found an increasing trend in the length of the most stressful high temperature summer period, increasing by 22 days since 1950. Over the past 20 years, Z. marina’s abundance has exhibited periods of decline followed by recovery, with recovery years associated with greater spring water clarity and less time spent at water temperatures > 28 °C. Although human disturbance and climatic factors have been altering these seagrass meadows, resilience has been evident by an increase in reproductive output and regrowth from Z. marina seedlings following declines, as well as expansions of Ruppia maritima into areas previously dominated by Z. marina.

Highlights

Recent global climate changes have affected a wide variety of plant communities with diverse geographical distributions
Human disturbance and climatic factors have been altering these seagrass meadows, resilience has been evident by an increase in reproductive output and regrowth from Z. marina seedlings following declines, as well as expansions of Ruppia maritima into areas previously dominated by Z. marina
Seagrass meadows have been identified as being among the most threatened ecosystems across the globe, as they have been experiencing declines in areal extent, and accelerated rates of decline [6,7]. Both direct and indirect stressors have been implicated in these losses, including increased anthropogenic sediment and nutrient loadings resulting in poor water quality conditions [6,8,9]

Summary

Introduction

Recent global climate changes have affected a wide variety of plant communities with diverse geographical distributions. Seagrass meadows have been identified as being among the most threatened ecosystems across the globe, as they have been experiencing declines in areal extent, and accelerated rates of decline [6,7]. Both direct and indirect stressors have been implicated in these losses, including increased anthropogenic sediment and nutrient loadings resulting in poor water quality conditions [6,8,9]. There has been an increased focus on the effects of current and future climate change factors on seagrass productivity and distribution [10,11,12]

Methods

Results

Conclusion