Experimental tests of snail grazing on turtle grass, Thalassia testudinum: evidence of resilience in short-term plant function to scarring of live tissues

Experimental tests of snail grazing on turtle grass, Thalassia testudinum: evidence of resilience in short-term plant function to scarring of live tissues | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Experimental tests of snail grazing on turtle grass, Thalassia testudinum: evidence of resilience in short-term plant function to scarring of live tissues Anjali D. Boyd, Iker R. Yturralde, Andres J. Moreno, Daisy Ponce, and 6 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9369564/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 4 You are reading this latest preprint version Abstract In coastal ecosystems, the intricate interactions among grazers, microorganisms, and plants play a crucial role in shaping plant health and ecosystem dynamics. Recent work has shown that snail grazing on live seagrass tissue creates wounds that can facilitate fungal infection, suggesting a pathway by which invertebrate grazers may exert top-down control over seagrass growth. However, whether density-dependent snail grazing translates into measurable impacts on fungal infection and seagrass health under field conditions remains untested. To address this gap, we conducted field surveys and experiments to examine how fungal infection in Thalassia testudinum blades and seagrass health varies with different densities of the herbivorous smooth tegula, Tegula fasciata snail in Bocas del Toro on the Caribbean coast of Panama. Field surveys documented snail scarring on seagrass blades and that density of smooth tegula in seagrass beds was positively associated with both scarring prevalence and increased brown tissue (indicative of fungal infection) in seagrass blades. Our six-week experimental manipulation testing densities of tegula snails (0, 1, 2, 4, and 6 snails per 625 cm 2 ) revealed no significant effects of snail density on seagrass metrics including biomass, productivity, shoot density, or degree of fungal colonization, despite visible emergence of radulation scars on blades. The only significant treatment effect was on total shoot number, where treatments with natural snail density (1 snail per 625 cm 2 ) produced more shoots than treatments with the highest snail density (6 snails per 625 cm 2 ). Although snail presence increased scarring on new growth blades relative to snail-free controls, tissue damage did not translate into detectable effects on seagrass biomass, productivity, or fungal colonization. These results suggest that T. testudinum can effectively compensate for snail grazing over short timescales, as it does with other grazers, such as turtles. Fungal biomass did not increase significantly with snail density or scarring presence, indicating that the grazer-pathogen facilitation pathway documented in other marine plant systems may not operate over short experimental timescales in turtlegrass. Together, these findings suggest a degree of ecological co-tolerance between T. testudinum and invertebrate grazers, though whether this resilience holds under sustained grazing pressure or compounding environmental stressors warrants further investigation. Thalassia testudinum Tegula fasciata seagrass resilience invertebrate grazing fungal infection top-down control Full Text Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 21 Apr, 2026 Reviewers invited by journal 21 Apr, 2026 Editor assigned by journal 20 Apr, 2026 First submitted to journal 09 Apr, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9369564","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":626792797,"identity":"55f5413b-ebe6-45e4-bbd0-6d4d96ed9063","order_by":0,"name":"Anjali D. 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Recent work has shown that snail grazing on live seagrass tissue creates wounds that can facilitate fungal infection, suggesting a pathway by which invertebrate grazers may exert top-down control over seagrass growth. However, whether density-dependent snail grazing translates into measurable impacts on fungal infection and seagrass health under field conditions remains untested. To address this gap, we conducted field surveys and experiments to examine how fungal infection in \u003cem\u003eThalassia testudinum\u003c/em\u003e blades and seagrass health varies with different densities of the herbivorous smooth tegula, \u003cem\u003eTegula fasciata\u003c/em\u003e snail in Bocas del Toro on the Caribbean coast of Panama. Field surveys documented snail scarring on seagrass blades and that density of smooth tegula in seagrass beds was positively associated with both scarring prevalence and increased brown tissue (indicative of fungal infection) in seagrass blades. Our six-week experimental manipulation testing densities of tegula snails (0, 1, 2, 4, and 6 snails per 625 cm\u003csup\u003e2\u003c/sup\u003e) revealed no significant effects of snail density on seagrass metrics including biomass, productivity, shoot density, or degree of fungal colonization, despite visible emergence of radulation scars on blades. The only significant treatment effect was on total shoot number, where treatments with natural snail density (1 snail per 625 cm\u003csup\u003e2\u003c/sup\u003e) produced more shoots than treatments with the highest snail density (6 snails per 625 cm\u003csup\u003e2\u003c/sup\u003e). Although snail presence increased scarring on new growth blades relative to snail-free controls, tissue damage did not translate into detectable effects on seagrass biomass, productivity, or fungal colonization. These results suggest that \u003cem\u003eT. testudinum\u003c/em\u003e can effectively compensate for snail grazing over short timescales, as it does with other grazers, such as turtles. Fungal biomass did not increase significantly with snail density or scarring presence, indicating that the grazer-pathogen facilitation pathway documented in other marine plant systems may not operate over short experimental timescales in turtlegrass. 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