Evidence that a hyperiid amphipod trophically links large scyphozoan jellyfish to Chinook Salmon in the Salish Sea
Presentation Abstract
The existence, causes and potential consequences of widespread increases in ‘jellyfish’ (ctenophores, medusae and salps) abundance are hotly debated topics in marine ecology. Jellyfish have often been considered trophic dead ends; consuming zooplankton and making it inaccessible to higher trophic levels. We investigated the possibility that a hyperiid amphipod (Hyperia medusarum) acts as a trophic linkage between a large scyphozoan jellyfish (Phacellophora camtschatica) and Chinook Salmon (Onchorhyncus tshawytscha) in the Salish Sea. Hyperia medusarum was a significant food source for juvenile Chinook Salmon in the Southern Gulf Islands in the summers of 2014 and 2015. Nematocysts were present in the foreguts of both amphipods parasitizing jellyfish and amphipods from juvenile Chinook Salmon stomachs, suggesting energy flow from the jellyfish to the salmon through the amphipods. Size frequencies and sex ratios differed significantly for amphipods obtained directly from jellyfish and those from Chinook Salmon stomachs, with salmon feeding primarily on large, female Hyperia. Juvenile Chinook Salmon may be preferentially picking female amphipods directly off medusae or preying on them during a life history event in which they leave their host. We discuss our results in the context of recent increases in the abundance of P. camtschatica in the Salish Sea (beginning early 1990s), and literature data that suggest hyperiid amphipods are becoming more prevalent in the diets of juvenile salmon in the Salish Sea and beyond.
Session Title
The Salish Sea Marine Survival Project- Novel Approaches, Project Status and Key Findings
Conference Track
Species and Food Webs
Conference Name
Salish Sea Ecosystem Conference (2016 : Vancouver, B.C.)
Document Type
Event
Start Date
2016 12:00 AM
End Date
2016 12:00 AM
Location
2016SSEC
Type of Presentation
Oral
Genre/Form
conference proceedings; presentations (communicative events)
Contributing Repository
Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.
Subjects – Topical (LCSH)
Jellyfishes--Salish Sea (B.C. and Wash.); Chinook salmon--Food--Salish Sea (B.C. and Wash.); Chinook salmon--Parasites--Salish Sea (B.C. and Wash.); Amphipoda--Salish Sea (B.C. and Wash.)
Geographic Coverage
Salish Sea (B.C. and Wash.)
Rights
This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.
Type
Text
Language
English
Format
application/pdf
Evidence that a hyperiid amphipod trophically links large scyphozoan jellyfish to Chinook Salmon in the Salish Sea
2016SSEC
The existence, causes and potential consequences of widespread increases in ‘jellyfish’ (ctenophores, medusae and salps) abundance are hotly debated topics in marine ecology. Jellyfish have often been considered trophic dead ends; consuming zooplankton and making it inaccessible to higher trophic levels. We investigated the possibility that a hyperiid amphipod (Hyperia medusarum) acts as a trophic linkage between a large scyphozoan jellyfish (Phacellophora camtschatica) and Chinook Salmon (Onchorhyncus tshawytscha) in the Salish Sea. Hyperia medusarum was a significant food source for juvenile Chinook Salmon in the Southern Gulf Islands in the summers of 2014 and 2015. Nematocysts were present in the foreguts of both amphipods parasitizing jellyfish and amphipods from juvenile Chinook Salmon stomachs, suggesting energy flow from the jellyfish to the salmon through the amphipods. Size frequencies and sex ratios differed significantly for amphipods obtained directly from jellyfish and those from Chinook Salmon stomachs, with salmon feeding primarily on large, female Hyperia. Juvenile Chinook Salmon may be preferentially picking female amphipods directly off medusae or preying on them during a life history event in which they leave their host. We discuss our results in the context of recent increases in the abundance of P. camtschatica in the Salish Sea (beginning early 1990s), and literature data that suggest hyperiid amphipods are becoming more prevalent in the diets of juvenile salmon in the Salish Sea and beyond.
Comments
This work is linked to a juvenile Chinook Salmon ecology project funded in part through the SSMSP. We have discussed this submission with Isobel Pearsall and she recommends that it be included as a 5 minute talk in an SSMSP session.