Water column structure and zooplankton distribution along

Trevor Channel, Barkley Sound

Andrew Hamilton

• http://collections.ic.gc.ca/

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

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Trevor Channel

Total Copepod Abundance -Trevor Channel

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Shallow Zooplankton Abundance -Trevor Channel

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EuphasiidsJelliesChaetognathsCopepods

Deep Zooplankton Abundance -Trevor Channel

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Total Zooplankton Biomass -Trevor Channel

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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

QuickTime™ and aTIFF (Uncompressed) decompressor

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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)

Fig. 5.

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)

Acknowledgements

Captain John of RV AltaChris (for getting dirty)Josie (for tinfoil and lab work)Rich (for CTD crash course)Maite (for baking lessons)High School research assistants

(for doing all the work)

Thankyou!