1. Oceanographic Factors Affecting Phytoplankton Distribution in Monterey Bay, CA
LT Adria McClain

2. Outline Intro to Phytoplankton Measuring Phytoplankton Concentration
Factors Affecting Phytoplankton Distribution
Physical
Upwelling
Nutrient Availability
Dissolved Gas
Topographic
References
Questions

3. Phytoplankton Autotrophic component of the plankton
Obtain energy thru photosynthesis; must live in euphotic zone (midlats: sfc to ~70m)
Primary Producers Create oxygen and organic compounds
6 H2O + 6 CO > C6H12O6 + 6 O2
Depend on macronutrients (nitrates, phosphates) for growth
Form base of marine trophic pyramid

4. Measuring Primary Productivity
Fluorometer affixed to an Autonomous Underwater Vehicle (AUV) or to a CTD
Chlorophyll concentration used to estimate biomass
Expose chlorophyll in phytoplankton cells to wavelengths of light that cause the pigment to fluoresce
Intensity of fluorescence read electronically to give direct measure of chlorophyll and quantity of plant material in water

5. Fluorometer Data
Monterey Bay Aquarium Research Institute (MBARI) AUV Survey for BIOLUME Campaign
Period of survey: 1/29/ PST to 1/30/ PST
CTD-AUV collected water temperature, salinity, pressure, dissolved gas concentration, chlorophyll concentration, etc
AUV programmed to follow sinusoidal course through water column (alternatively diving and surfacing) along grid pattern
CTD data from OC3570 student cruise aboard R/V Pt. Sur

6. Upwelling NorCal: Northwesterly winds lead to upwelling
Cold, nutrient-rich water rises to surface
Phytoplankton blooms occur 6-10 days after an upwelling event (Service et al., 1998 and Fiedler et al., 1998)

7. Upwelling

8. Phytoplankton Bloom?
Wind direction and wind speed from MBARI M1: 36.7oN 122.0oW
NW winds of 8-10m/s on or around 17 Jan
Winter n’westerlies less strong than summer n’westerlies (weaker upwelling events in winter)
NOAA Image: appears to be an upwelling event Jan 18-21
AUV Chlorophyll concentration data from 29/30 Jan
“Bloom” w/in 10 day period following upwelling event
Increased wind-forcing linked to increases in primary production and surface chlorophyll (Croll et al.,2005)

9. Nutrient Availability
Increasing nitrogen in ocean linked to high productivity (Sverdrup, pp. 389)
Inorganic nutrients required for primary production include nitrate (NO3-) and phosphate (PO43-)
Nitrogen and phosphorus depleted by photosynthesizing organisms during times of high productivity and rapid reproduction (Garrison, pp. 234)

10. Dissolved Gas Generally, colder water contains more gas at saturation
Photosynthesis near the surface increases the amount of dissolved oxygen
O2 least abundant just below euphotic zone due to marine animals respiring at middle depths
(Garrison, pp )

11. Topography (Ryan et al., 2005)
Observed during 2005 MBARI AUV Survey
Internal tides and wind-driven currents caused cold, dense water to flow from Monterey Canyon
Water flowing over continental shelf produced a plume of turbid water
Increased phytoplankton concentration observed above plume; plume likely carried macronutrients upward

12. Topography (Ryan et al., 2005)
Observed during 2000 MBARI AUV Survey
Incoming tide flowed over edge of canyon; produced 10m internal wave (“lee wave”)
Phytoplankton layer 10-20m below surface to the north; highly concentrated phytoplankton layer nearest canyon
Wave crest “bisected” phytoplankton layer thereby changing its properties

13. References
Canyons, currents, and algal blooms— How Monterey Canyon influences the growth of microscopic marine algae April 2005
Croll, D.A., et al., From wind to whales: trophic links in a coastal upwelling system. Marine Ecology Progress Series, 289,
--, et al., An integrated approach to the foraging ecology of marine birds and mammals. Deep-Sea Research II, 45,
Fiedler, P.C., et al., Blue whale habitat and prey in the California Channel Islands. Deep Sea Research II, 45,
Garrison, T., Essentials of oceanography (2nd Ed.). Brooks/Cole, Pacific Grove, CA.
NOAA Fisheries Service: Live access to ERD environmental data
Olivieri, R.A., F.P. Chavez, A model of plankton dynamics for the coastal upwelling system of Monterey Bay, California. Deep-Sea Research II, 47,
Ryan, J.P., F.P. Chavez, J.G. Bellingham, Physical-biological coupling in Monterey Bay California: topographic influences on phytoplankton ecology. Marine Ecology Progress Series, 287,

14. References
Service, S.K., J.A. Rice, F.P. Chavez, Relationship between physical and biological variables during the upwelling period in Monterey Bay, CA. Deep-Sea Research II, 45,
Sverdrup, K.A., A.C. Duxbury, A.B. Duxbury, An introduction to the world’s oceans (8th Ed.), McGraw-Hill, New York, NY.

15. Questions?