Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Related Publications
• Related Datasets
• Parameters
• Instruments
• Project Information
• Funding

We used a substitutive design to test the effects of eelgrass (Zostera marina) genotypic identity (eight genotypes), diversity (monocultures of 1 genotype vs. polycultures of 4 genotypes), and temperature (ambient or + 3.2° C) on the prevalence and intensity of Labyrinthula over eight weeks in an array of flow-through 120-L mesocosms at the Bodega Marine Laboratory in Bodega Bay, CA. We assigned ten pots - two unique polyculture combinations and each of the eight monocultures - to each of ten mesocosms, with five mesocosms per temperature treatment (see DuBois et al. 2020 for a diagram of the experimental set up). All mesocosms received sand-filtered flow-through seawater at a rate of approximately 0.8-1.0 L min^-1. We allowed the plants to acclimate for one month prior to initiating the temperature treatments. We maintained an ambient temperature treatment by cooling flow-through seawater in a head tank by approximately 1˚C using an Aqua Logic Delta Star in-line titanium chiller. Seawater in the elevated temperature treatment was raised approximately 3˚C above the ambient treatment in a separate header tank using Process Technologies titanium immersion heaters. This level of warming mimicked the 2014-15 extreme warming events in the Northern Pacific called “The Blob”, which raised summer ocean temperatures three standard deviations above the long-term average (Sanford et al. 2019).

Life Sciences Identifiers (LSID) for taxonomic names:
Zostera marina (urn:lsid:marinespecies.org:taxname:145795)
Labyrinthula zosterae (urn:lsid:marinespecies.org:taxname:395093)
Labyrinthula (urn:lsid:marinespecies.org:taxname:119090)

Code that includes temperature analysis associated with this experiment: All code was written and run in R (version 3.6.1, www.R-project.org). Github repository link: https://github.com/schenckf/BWE_Experiment and Zenodo DOI: https://doi.org/10.5281/zenodo.7129500. A general description of the code is included in the repository release.

BCO-DMO Processing:

NSF Award Abstract:
Disease outbreaks in the ocean are increasing, causing losses of ecologically important marine species, but the factors contributing to these outbreaks are not well understood. This 5-year CAREER project will study disease prevalence and intensity in two marine foundation species - the seagrass Zostera marina and the Eastern oyster Crassostrea virginica. More specifically, host-disease relationships will be explored to understand how genetic diversity and population density of the host species impacts disease transmission and risk. This work will pair large-scale experimental restorations and smaller-scale field experiments to examine disease-host relationships across multiple spatial scales. Comparisons of patterns and mechanisms across the two coastal systems will provide an important first step towards identifying generalities in the diversity-density-disease relationship. To enhance the broader impacts and utility of this work, the experiments will be conducted in collaboration with restoration practitioners and guided by knowledge ascertained from key stakeholder groups. The project will support the development of an early career female researcher and multiple graduate and undergraduate students. Students will be trained in state-of-the-art molecular techniques to quantify oyster and seagrass parasites. Key findings from the surveys and experimental work will be incorporated into undergraduate courses focused on Conservation Biology, Marine Biology, and Disease Ecology. Finally, students in these courses will help develop social-ecological surveys and mutual learning games to stimulate knowledge transfer with stakeholders through a series of workshops.

The relationship between host genetic diversity and disease dynamics is complex. In some cases, known as a dilution effect, diversity reduces disease transmission and risk. However, the opposite relationship, known as the amplification effect, can also occur when diversity increases the risk of infection. Even if diversity directly reduces disease risk, simultaneous positive effects of diversity on host density could lead to amplification by increasing disease transmission between infected and uninfected individuals. Large-scale field restorations of seagrasses (Zostera marina) and oysters (Crassostrea virginica) will be utilized to test the effects of host genetic diversity on host population density and disease prevalence/intensity. Additional field experiments independently manipulating host genetic diversity and density will examine the mechanisms leading to dilution or amplification. Conducting similar manipulations in two marine foundation species - one a clonal plant and the other a non-clonal animal - will help identify commonalities in the diversity-density-disease relationship. Further, collaborations among project scientists, students, and stakeholders will enhance interdisciplinary training and help facilitate the exchange of information to improve management and restoration efforts. As part of these efforts, targeted surveys will be used to document the perceptions and attitudes of managers and restoration practitioners regarding genetic diversity and its role in ecological resilience and restoration.