Abstract Title

Session S-02D: Pelagic Ecology in the Salish Sea II

Keywords

Species and Food Webs

Start Date

30-4-2014 1:30 PM

End Date

30-4-2014 3:00 PM

Description

Jellyfish may play a key role in pelagic food webs. Their interactions with fish are potentially complex, as they may compete with pelagic fish for prey, may be prey for fish and may be a predator on larval fish. To investigate these interactions, we must also understand how the trophic role of jellyfish varies with factors such as size, species, season and environmental conditions. Hypoxia, in particular, is an increasing problem worldwide and is thought to likely affect fish-jellyfish interactions. We estimated the trophic level of jellyfish using stable isotope analysis on multiple large jellyfish species collected in Hood Canal, Washington. A paired-site sampling design was used to compare hypoxic and non-hypoxic regions. Jellyfish and prey samples were collected from June to October during two years at each site and across a size range. After determining the influence of these factors on the trophic role of jellyfish, we will then be able to better investigate diet overlap with zooplanktivorous fish. Preliminary results indicate that size does not affect the trophic level of jellyfish. Jellyfish also appear to have similar isotopic signatures to fish, which allows for the possibility of competition between jellyfish and fish.

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Apr 30th, 1:30 PM Apr 30th, 3:00 PM

Trophic position of jellyfish in the pelagic food web of Hood Canal

Room 611-612

Jellyfish may play a key role in pelagic food webs. Their interactions with fish are potentially complex, as they may compete with pelagic fish for prey, may be prey for fish and may be a predator on larval fish. To investigate these interactions, we must also understand how the trophic role of jellyfish varies with factors such as size, species, season and environmental conditions. Hypoxia, in particular, is an increasing problem worldwide and is thought to likely affect fish-jellyfish interactions. We estimated the trophic level of jellyfish using stable isotope analysis on multiple large jellyfish species collected in Hood Canal, Washington. A paired-site sampling design was used to compare hypoxic and non-hypoxic regions. Jellyfish and prey samples were collected from June to October during two years at each site and across a size range. After determining the influence of these factors on the trophic role of jellyfish, we will then be able to better investigate diet overlap with zooplanktivorous fish. Preliminary results indicate that size does not affect the trophic level of jellyfish. Jellyfish also appear to have similar isotopic signatures to fish, which allows for the possibility of competition between jellyfish and fish.