Water column structure and zooplankton distribution along Trevor

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 - 5 m, deep - 10 m off bottom (20 -170 m)) Zooplankton abundance, biomass, and diversity Physics: CTD/oxygen profiles

1 2 3 4 5

Trevor Channel Open ocean

Results • Zooplankton abundance and biomass highest inside Trevor Channel • Zooplankton diversity highest in open ocean • Higher abundance and biomass at deep sites

W Open Ocean E Trevor Channel Low Salinity Low Oxygen

Krill behavior as recorded by acoustic doppler current profilers in the Gullmarsfjord Liljebladh and Thomasson Journal of Marine Systems (2001) http: //www. awi-bremerhaven. de/Eistour/krill-d. html

Fig. 5.

Oxygen saturation Ice Oxygen deficiency Krill Maximum Zooplankton Mortality

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 Alta Chris (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!