Response of eelgrass (Zostera marina) to an adjacent Olympia oyster restoration project

PLoS One. 2021 Oct 7;16(10):e0258119. doi: 10.1371/journal.pone.0258119. eCollection 2021.

Abstract

Recent restoration efforts for the native Olympia oyster, Ostrea lurida, are commonly motivated by potential return of oyster-associated ecosystem services, including increased water filtration. The potential impact of such restoration on another species of ecological concern, eelgrass, Zostera marina, is unclear, but has been hypothesized to be positive if oyster filter feeding increases light penetration to eelgrass. For two years after construction of an oyster restoration project, we assessed the response of adjacent eelgrass (impact) compared to control and reference eelgrass beds by monitoring changes in light intensity, eelgrass shoot density, biomass, leaf morphometrics, and epiphyte load. We observed lower light intensity consistently over time, including prior to restoration, near the constructed oyster bed relative to the control and one of the reference locations. We also observed minor variations between control and impact eelgrass morphology and density. However, the changes observed were not outside the range of natural variation expected in this system, based upon comparisons to reference eelgrass beds, nor were they detrimental. This limited impact to eelgrass may be due in part to the incorporation of a buffer distance between the restored oyster bed and the existing eelgrass bed, which may have dampened both positive and negative impacts. These findings provide evidence that Olympia oyster restoration and eelgrass conservation goals can be compatible and occur simultaneously.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Conservation of Natural Resources*
  • Ecosystem*
  • Humans
  • Ostrea / growth & development*
  • Water / chemistry
  • Zosteraceae / growth & development*

Substances

  • Water

Grants and funding

Funding for the oyster restoration project and the resulting monitoring was provided by NOAA Restoration Center and California State Coastal Conservancy (DZ; Project No. 11-058-01; https://scc.ca.gov), California State University Fullerton Department of Biological Science (DZ, SB; https://www.fullerton.edu/biology), CSU Fullerton Senior Intramural Award (DZ), Zucchero Management Incorporated (DZ), and The CSU Council on Ocean Affairs, Science and Technology (DZ, SB; https://www2.calstate.edu). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.