Trophic Interactions of Hydromedusae Across Multiple Spatial Scales
| dc.contributor.advisor | Sutherland, Kelly | |
| dc.contributor.author | Corrales, Marco | |
| dc.date.accessioned | 2022-05-10T15:05:38Z | |
| dc.date.available | 2022-05-10T15:05:38Z | |
| dc.date.issued | 2022-05-10 | |
| dc.description.abstract | Cnidarian medusae are predators that structure pelagic ecosystems. Studies on their predatory impact have focused on big cruising scyphomedusae even though hydrozoans represent 60% of all medusan diversity and prey upon a wide range of taxa. It is unclear how hydromedusan feeding behavior relates to their effects on marine food webs. In this dissertation, I present three studies to illustrate how traits of planktonic predators determine food-web level processes. In Chapter II I determined how passive (sinking) and active (swimming) feeding behavior affects pre-encounter responses of prey to the medusae-induced fluid motion. I showed how passive prey were ingested during both feeding behaviors, whereas flow-sensing prey such as copepods escaped the predator’s active feeding behavior but were unable to detect the predator’s passive sinking behavior and were ingested. Fluid deformation values during passive feeding were below the values that trigger escape responses of copepods. I explored in Chapter III how the environment mediates trophic interactions through effects on hydromedusan feeding behavior. I quantified in situ turbulent kinetic energy and hydromedusan tentacle length and bell pulsation frequency at two sites in Friday Harbor, Washington: a nearshore site protected from the channel flow and the Friday Harbor Marina, influenced by channel flow. The protected site presented a shorter range of turbulence compared to the marina. Hydromedusan tentacle length was larger in the protected site and tentacle length was larger in turbulence from 1-5 cm2 s-3, but at higher turbulence tentacle length decreased. In Chapter IV I collected mesozooplankton from five stations along two cross-shelf transects in the Northern California Current during winter and summer of 2018-2019 to determine prey resource use by hydromedusae and determine temporal shifts in their trophic niche. Hydromedusae fed mostly on copepods, appendicularians, and invertebrate larvae, but their diets showed seasonal shifts in prey resource driven by the abundant species C. gregaria, which fed mostly on copepod eggs during winter and fed mostly on appendicularians and copepods during summer. Prey selectivity for copepod eggs increased during winter for C. gregaria and E. indicans. This dissertation includes both previously published and unpublished coauthored material. | en_US |
| dc.identifier.uri | https://hdl.handle.net/1794/27153 | |
| dc.language.iso | en_US | |
| dc.publisher | University of Oregon | |
| dc.rights | All Rights Reserved. | |
| dc.title | Trophic Interactions of Hydromedusae Across Multiple Spatial Scales | |
| dc.type | Electronic Thesis or Dissertation | |
| thesis.degree.discipline | Department of Biology | |
| thesis.degree.grantor | University of Oregon | |
| thesis.degree.level | doctoral | |
| thesis.degree.name | Ph.D. |
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