Diversity and Survival of Macrofauna associated with a Non-Native Foundational Species

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dc.contributor.advisorBlakeslee, April MH
dc.contributor.authorLee, Timothy Seung-chul
dc.contributor.departmentBiology
dc.date.accessioned2023-09-14T13:04:10Z
dc.date.available2023-09-14T13:04:10Z
dc.date.created2023-07
dc.date.issued2023-07-24
dc.date.submittedJuly 2023
dc.date.updated2023-09-12T17:47:58Z
dc.degree.departmentBiology
dc.degree.disciplinePHD-Interdisc Biological Sci
dc.degree.grantorEast Carolina University
dc.degree.levelDoctoral
dc.degree.namePh.D.
dc.description.abstractThrough globalization and increased anthropogenic movement, many non-native foundation species have established across the world. These foundation species have impacted ecological communities in myriad of ways, including but not limited to reducing native biodiversity, changing biogeochemistry, and altering physical environment. Marine macroalgae, or seaweeds, are one of the major groups of foundational species in coastal habitats throughout the world. Seaweeds play vital roles as ecosystem engineers by provide valuable habitat for macrofauna and protect their associated communities from thermal stress. Many seaweeds around the world’s coastlines are also non-native, and some species have transformed native habitat by bringing novel structural complexity. The red seaweed Gracilara vermiculophylla, native to northwestern Pacific, has invaded much of the temperate estuarine ecosystems in Northern Hemisphere. Along the U.S. East Coast, this seaweed has physically transformed soft-sediment habitats by providing complex three-dimensional structure, thus providing refuge, shelter, and microhabitats for native macroinvertebrates. I approached this study with three chapters to understand 1) the biogeographic patterns of free-living and parasitic macroinvertebrates associated with G. vermiculophylla along the U.S. east coast, 2) survivability of macroinvertebrate in habitats with G. vermiculophylla presence coupled with rising seawater temperatures, and 3) comparisons of macroinvertebrate diversity between G. vermiculophylla and the native foundational species, seagrasses. For the first chapter, I sampled G. vermiculophylla thalli, its associated free-living and parasitic macroinvertebrates, and the abiotic environmental parameters along the U.S. east coast, from South Carolina to New Hampshire in May-August 2019, spanning across three biogeographic regions. Using Generalized Linear Mixed Model, I found that biogeographic region, site, G. vermiculophylla biomass, and the interaction of biogeographic region with G. vermiculophylla appeared in top models for free-living macroinvertebrates’ response variables (abundance, richness, and diversity). For parasitic invertebrates, I found that according to Generalized Linear Models, G. vermiculophylla biomass was the predictor appearing top performing model for parasitic prevalence and richness, while biogeographic region was the sole predictor in a top performing model for parasitic diversity. For the second chapter, from February-March 2021 I conducted a lab experiment with Ilyanassa obsoleta snail on its survivability in habitats with G. vermiculophylla presence and rising seawater temperature, with focus on North Carolina. The eastern mudsnail Ilyanassa obsoleta co-occurs with G. vermiculophylla throughout much of the east coast, and highly abundant, making this invertebrate an ideal study organism. I tested survivability of I. obsoleta at three seawater temperatures (27, 32, and 36 oC) in two habitat treatments (with and without G. vermiculophylla) for three weeks, two trials each. I found that I. obsoleta mortality was greatest in 36 oC, followed by 32 and 27 oC. I also found that mortality of I. obsoleta was higher in G. vermiculophylla habitat treatment than without the seaweed, and found that infected I. obsoleta perished faster at higher temperatures. Furthermore, we found that oxygen diminished faster in habitats with G. vermiculophylla at higher temperatures, which suggests that the interaction of non-native seaweed and seawater temperature rise can possibly create anoxic conditions. For the final chapter, I collected free-living macroinvertebrates associated with the non-native foundational species (G. vermiculophylla) and native foundational species (seagrasses) that co-occurs in North Carolina coastlines. Seagrasses play critical role as primary producers in coastlines and provide valuable habitat for many macroinvertebrates. North Carolina coastlines are unique because it is the only region in the western Atlantic coast where two species of seagrasses, the eelgrass (Zostera marina) and shoalgrass (Halodule wrightii) co-occur. I sampled multiple replicates of G. vermiculophylla thalli, fronds of seagrasses, and their associated macroinvertebrates from May-July 2021. Overall, I found that macroinvertebrate abundances were higher in the non-native G. vermiculophylla than seagrasses. Within seagrass species comparisons, I found that macroinvertebrate richness was higher in Z. marina than H. wrightii suggesting that some seagrasses may provider habitats of higher quality. Along the U.S. East Coast, G vermiculophylla can accommodate diverse assemblage of macroinvertebrates. Patterns of macroinvertebrates may vary depending on the G. vermiculophylla biomass and biogeographic regions. However, G. vermiculophylla may be capable of generating habitats with low-oxygen levels with high seawater temperature, thereby potentially harming native macroinvertebrates in environments with thermal stress. Finally, G. vermiculophylla may accommodate greater abundances of macroinvertebrates than native foundational species, but it is important to recognize that seaweeds and seagrasses serve different roles in coastal ecosystems. As G. vermiculophylla continues to transform coastal habitats, it is important to continue monitoring macroinvertebrate to better understand how these communities and other organisms in the coastal food web are affected by this foundational non-native species.
dc.format.mimetypeapplication/pdf
dc.identifier.urihttp://hdl.handle.net/10342/13138
dc.language.isoen
dc.publisherEast Carolina University
dc.subjectFoundation species, non-native species, Gracilaria vermiculophylla, parasites, invasion, Ilyanassa obsoleta, invertebrates, seagrass
dc.titleDiversity and Survival of Macrofauna associated with a Non-Native Foundational Species
dc.typeDoctoral Dissertation
dc.type.materialtext

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