Streaming Media
Presentation Abstract
Deoxygenation and hypoxia are affecting marine trophic webs throughout the world’s oceans. Hood Canal, Puget Sound is a basin that experiences seasonal hypoxia due to its restricted circulation and high primary production. The region supports a large secondary trophic level dominated by mesozooplankton, and particularly copepods. Studies suggest that zooplankton exhibit changes in their vertical distribution when faced with low oxygen concentrations and even face mortality when concentrations fall below ~1 mg/l. Because zooplankton are an important food resource for many aquatic animals, a shift in their distribution could have major implications for the food chain. This study examines how low oxygen levels affect the distribution of copepods relative to the oxygen minimum to explore how predator/prey interactions may be impacted by changing water conditions. Samples were collected in summer and fall 2017 and 2018 across normoxic and hypoxic conditions in Hood Canal. Zooplankton pumps and depth-stratified net tows were deployed during the day and night to observe diel vertical migration (DVM), and a camera equipped with a telecentric lens was mounted on a profiling mooring, which collected a continuous stream of photos during multiple profiles of the water column each day. A convolutional neural network, ResNet-18, was used to process the thousands of images collected in situ. Preliminary results suggest oxygen levels significantly impact species composition and distribution in the water column. In-situ imaging data are currently being analyzed to substantiate these findings and expand them across a broad range of oxygen conditions.
Session Title
Ocean Productivity & Nutrients
Conference Track
SSE3: The Circle of Life
Conference Name
Salish Sea Ecosystem Conference (2022 : Online)
Document Type
Event
SSEC Identifier
SSE-traditionals-189
Start Date
26-4-2022 9:45 AM
End Date
26-4-2022 11:15 AM
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)
Hypoxia (Water)--Washington (State)--Hood Canal; Marine ecosystem management--Washington (State)--Hood Canal; Copepoda--Washington (State)--Hood Canal
Geographic Coverage
Salish Sea (B.C. and Wash.); Hood Canal (Wash.)
Rights
Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.
Type
Text
Language
English
Format
application/pdf
Included in
Fresh Water Studies Commons, Marine Biology Commons, Natural Resources and Conservation Commons, Terrestrial and Aquatic Ecology Commons
Effects of Low Oxygen Levels on Copepod Size Distribution with Depth in Hood Canal
Deoxygenation and hypoxia are affecting marine trophic webs throughout the world’s oceans. Hood Canal, Puget Sound is a basin that experiences seasonal hypoxia due to its restricted circulation and high primary production. The region supports a large secondary trophic level dominated by mesozooplankton, and particularly copepods. Studies suggest that zooplankton exhibit changes in their vertical distribution when faced with low oxygen concentrations and even face mortality when concentrations fall below ~1 mg/l. Because zooplankton are an important food resource for many aquatic animals, a shift in their distribution could have major implications for the food chain. This study examines how low oxygen levels affect the distribution of copepods relative to the oxygen minimum to explore how predator/prey interactions may be impacted by changing water conditions. Samples were collected in summer and fall 2017 and 2018 across normoxic and hypoxic conditions in Hood Canal. Zooplankton pumps and depth-stratified net tows were deployed during the day and night to observe diel vertical migration (DVM), and a camera equipped with a telecentric lens was mounted on a profiling mooring, which collected a continuous stream of photos during multiple profiles of the water column each day. A convolutional neural network, ResNet-18, was used to process the thousands of images collected in situ. Preliminary results suggest oxygen levels significantly impact species composition and distribution in the water column. In-situ imaging data are currently being analyzed to substantiate these findings and expand them across a broad range of oxygen conditions.
