Water column structure and zooplankton distribution along
Trevor Channel, Barkley Sound
Andrew Hamilton
Observations
•Strong sound scattering layer at depth in Trevor Channel
•Anoxic layer at depth in Trevor Channel
•Shallow sill restrict water mass mixing
•Abundant zooplankton collected during net tows
•Research Question
Is spatial variability in zooplankton abundance and distribution related to physical oceanographic parameters?
•Observations Required
•Biology: Vertical and horizontal patterns of zooplankton abundance, biomass, and diversity
•Physics: Profiles of temperature, salinity, and oxygen
Significance
•Zooplankton consume phytoplankton - indication of Primary Productivity
•Zooplankton consumed by higher trophic levels (fish, whales)
•Influence local fisheries, aquaculture, ecotourism
•Physical - biological coupling affects entire ecosystem(productivity, nutrient and carbon cycling)
•Methods
5 station transect along Trevor Channel
Biology: horizontal zooplankton net tows (shallow - 5m, deep - 10m off bottom (20-170m))
Zooplankton abundance, biomass, and diversity
Physics: CTD/oxygen profiles
Total Copepod Abundance -Trevor Channel
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Number of Copepods
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ShallowDeep
Shallow Zooplankton Abundance -Trevor Channel
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Number of Zooplankton
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EuphasiidsJelliesChaetognathsCopepods
Deep Zooplankton Abundance -Trevor Channel
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Number of Zooplankton
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EuphasiidsJelliesChaetognathsCopepods
Results
•Zooplankton abundance and biomass highest inside Trevor Channel
•Zooplankton diversity highest in open ocean
•Higher abundance and biomass at deep sites
WW EE
Trevor ChannelTrevor Channel
Low OxygenLow Oxygen
Low SalinityLow Salinity
Open OceanOpen Ocean
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are needed to see this picture.
http://www.awi-bremerhaven.de/Eistour/krill-d.html
Krill behavior as recorded by acoustic doppler current profilers in the Gullmarsfjord
Liljebladh and ThomassonJournal of Marine Systems (2001)
Zooplankton Mortality
Zooplankton Mortality
Oxygen deficiencyOxygen deficiency
Oxygen saturationOxygen saturation
IceIce
Krill MaximumKrill Maximum
Conclusions
•Zooplankton abundance and distribution is related to water mass characteristics
•Physical - biological relationship is complex
•Will directly compare temperature, salinity, and oxygen profiles to zooplankton results
•More sampling helpful (vertical stratification, duplicate net tows, phytoplankton profiles)