Life Attached: Examining the Implications of Epibiosis on a North Pacific Cirripede and a Gulf of Mexico Seep Sabellid
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Date
2025-02-24
Authors
Rice, Lauren
Journal Title
Journal ISSN
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Publisher
University of Oregon
Abstract
Epibiotic species, which can either facultatively or obligatorily settle on living hosts, are commonly found in marine habitats. Despite this commonality, the biology and ecology for many epizoic organisms remain unknown and understudied. In this dissertation, I investigated how two marine invertebrate species accommodate life on living hosts.In Chapter II, I discuss the reproductive and settlement patterns for the barnacle Solidobalanus hesperius and how they correlate to the molting patterns for host crab species in the Oregon subtidal. I found that S. hesperius reproduces year-round and that brooded embryos hatch in approximately a week. Furthermore, I utilized a new method to examine the spatial distributions of barnacle individuals on their crab hosts and they were tightly correlated to the microtopography of the host carapace.
The remaining chapters of the dissertation focus on a facultative epibiotic relationship found at methane seeps in the Gulf of Mexico, involving a sabellid polychaete species. In Chapter III, we found that the species are gregarious settlers and are abundant within the methane seep habitats investigated. Furthermore, we present morphological and phylogenetic evidence and identify the sabellid as belonging to a new genus and species: Seepicola viridiplumi sp. nov.
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As the newly described sabellid is facultatively epibiotic, Chapter IV examined the trophic ecology of the species using stable isotopes. Additional tables showing the statistical pairwise comparisons highlighting the effects of season, sample site, and microhabitat on carbon, nitrogen, and sulfur isotopic ratios are provided as supplemental materials. We found that S. viridiplumi are generalist suspension feeders within the methane seeps and, using microbial evidence, show that the species does not rely on chemosynthetic symbionts. The rarefaction curves for the sequencing depth is also provided in the supplemental material section. However, individuals can occupy differing trophic niches depending on whether they are epibiotic or free-living.
The different trophic niches occupied by epibiotic and free-living S. viridiplumi individuals may impact other aspects of the biology for this species. To test this, we examined and compared the reproductive output for individuals from each microhabitat using paraffin histology. In doing so, we found that epibiotic individuals consistently had slightly larger oocytes and higher levels of fecundity. The individual oocyte size distributions for all female sabellids examined in this study are shown as a supplemental figure. We also observed an apparent lack of gametogenic seasonality in this sabellid species.
Taken together, the work presented in this dissertation provides unique insights into how epibiotic associations can develop and persist within an ecosystem. The results also provide additional insight into the adaptations and biology for epizoic species, which can aid in attempts for modeling community functioning.
This dissertation includes unpublished co-authored material.
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Keywords
Association, Epizoic, Hydrocarbon Seep, Reproduction, Settlement, Symbionts