This dataset includes outputs from statistical analyses of differences in microbial taxa (amplicon sequence variant or ASV) abundance among two groups of seagrass, Zostera marina, genotypes: those that showed reduced Labyrinthula zosterae parasites when warmed vs those that showed increased L. zosterae parasites when warmed; and two seawater temperature treatments: ambient or elevated +3.2oC. Data were collected as part of a mesocosm study at the Bodega Marine Laboratory examining the independent and interactive effects of warming, host genotypic identity, and host genotypic diversity on the prevalence and intensity of infections of seagrass by the wasting disease parasite L. zosterae. These data were published in Schenck et al (2022). Related sequence data from this experiment is accessible from the National Center for Biotechnology Information (NCBI) BioProject PRJNA716355.

Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Supplemental 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. In July 2015, we created ten unique polyculture combinations of four genotypes (4 genotypes per experimental pot) randomly drawn from a pool of eight genotypes; all eight genotypes were also grown in monoculture (1 genotype per pot). We filled pots (8.9 x 8.9 cm) with coarsely sieved sediment collected from Bodega Harbor, and planted 4 shoots per pot, matching the lower range of average field densities reported for Bodega Harbor (Ha and Williams 2018) to allow for growth during the experiment. Plants were originally collected in Bodega Harbor, CA in 2012, confirmed to be unique genotypes using 11 DNA microsatellite loci developed specifically for Z. marina (Abbott et al. 2018), and propagated in separate flow through mesocosms at BML.

At the end of the experiment (10 weeks), we collected and preserved the top half of the focal leaf in individual plastic bags sealed with 30 ml of silica (Flower Drying Art Silica Gel; Activa) for subsequent DNA extraction and quantitative PCR to estimate Labyrinthula zosterae cells as a proxy for infection (Bergmann et al. 2011, Bockelmann et al. 2013, Groner et al. 2021).

We collected 2 cm of the focal leaf from directly below the midpoint and stored the tissue at -80˚C for later microbiome analyses to assess whether particular leaf microbial taxa changed in association with Labyrinthula presence on the focal leaf. From these samples, we selected a subset of 84 leaf microbial samples evenly distributed across temperature treatments and across genotypes in monoculture. We did not assess leaf microbiomes in genotypic polycultures. We extracted the surface community of these leaf segments with a modified protocol for the DNeasy Powersoil Kit (Qiagen) and sequenced the V4-V5 region of the 16S rRNA gene on an Illumina MiSeq to analyze differences in the leaf microbiome between treatments and among genotypes. Specifically, to extract the surface community of leaf segments we used a modified protocol for the DNeasy Powersoil Kit (Qiagen) where we first vortexed leaf samples in 500ul of MilliQ water, and then extracted the supernate of each sample. Extraction success was verified via Qubit dsDNA HS assay kit. We PCR-amplified the V4-V5 region of the 16S rRNA gene and then sequenced pooled barcoded fragments on an Illumina MiSeq through the Integrated Microbiome Resource at Dalhousie University (Halifax, NS; Comeau et al. 2017).

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)

Coverage: Coastal New England

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.