Monterey Bay Aquarium Research Institute
CANON Initiative
Case study:
Zooplankton

Presented by Dave Checkley and Robert Vrijenhoek

Motivations, broader impact of zooplankton:

Zoopankton are good indicators of ecosystem health and function. They are surrogates of important processes and help to indicate certain types of environmental conditions such as concentrations of marine toxins. They are key to the food web.

A key question is whether the biodiversity of zooplankton is changing with regards to zooplankton consumption of particles, movement, and role as fish food.

The tiny tintinnid zooplankton
The zooplankton tintinnid. Source: Dave Checkley

Diverse sizes and types

Zooplankton widely vary both in sizes and types.Macrozooplankton, are up to 10 millimeters (mm) long, mesozooplankton, range in size from 0.1-10 millimeters long, and microzooplankton, which range in size from 10-100 micrometers (um) long.

Dynamics

Zooplankton play an important role as fish food, especially for the Pacific salmon. They also play a significant role in the biological pump and carbon cycle by consuming particles.

Current autonomous samplers

Researchers can only sample certain segments of the entire zooplankton spectrum. The autonomous underwater vehicle can sample a small parcel of water by detecting aggregations of zooplankton. This aggregation can be characterized by its gene flow, patch size, formation, and diversity in order to find the best sample.

Sounding oceanographic lagrangian observe +Laser optical plankton counter

picture of a SOLOPC being lowered into the ocean
Sounding Oceanographic Laser Optical Plankton Counter instrument is lowered into the ocean. Source: Dave Checkley
  • Length-255 centimeters
  • Diameter-17 centimeters
  • Weight
    • 36 kilograms (air)
    • 0 ± 100 grams (water)
  • Speed
    • 23 centimeters sec-1 (descent)
    • 15 centimeters sec-1 (ascent)
  • Depth range-0 - 600 meters
  • Number of dives
    • 0 - 600 meters
    • 190 to 300 meters
  • Telemetry-Iridium
  • Position
    • Global Positioning System
    • SeaBird Conductivity Temperature and Depth Instrument
  • Sensors
    • Brooke Ocean Technology
    • Laser Optical Plankton Counter
    • WET Labs Environmental Characterization Optics (ECO) Puck
  • Laser Optical Plankton Counter cross section-49 cm squared.
  • Laser Optical Plankton Counter- volume filtered- 0.49 meters cubed per 100-m profile
  • Cost (Components)- $54,000

Autonomous underwater vehicle with laser optical plankton counter, real time flow imaging and classification, and conductivity, temperature, and depth instruments

AUV with LOPC, REFLICS, CTD
Image of an AUV with the instruments LOPC, REFLICS, and CTD. Source: Dave Checkley

There are tradeoffs with using certain instruments for AUVs. For instance, the Laser Optical Plankton Counter (LOPC) has low resolution, but a higher count rate of zooplankton.

The Real Time Flow Imaging and Classification (REFLICS) instrument has a higher resolution, but a lower frame rate. It also has a real-time flow imaging and classification system.


Characterizing a water sample

The first critical step is the preservation of the water sample. The zooplankton cytometer (cytobot) helps to identify the species as well as specific organisms structures. A wide variety of sampling devices should be used to identify the species. Some limitations of the current sampling system include the need to collect larger water samples. Another area of improvement is to use acoustic methods in order to better estimate the size of a zooplankton patch, so that a large concentration can be effectively sampled. Nets and meshes could also be used to better concentrate the zooplankton for effective sampling. There are also limitations as to using the video plankton recorder.


Images of various zooplankton taken from the REFLIC instrument on AUV
Images of various zooplankton taken from the REFLIC instrument on AUV. Source: Dave Checkley

Future autonomous samplers

Future autonomous samplers can be improved in order to better characterize zooplankton species. A larger "gulper" instrument could be developed in order to capture organisms that are larger than mesozooplankton (>10 mm).There could be "pre-gulp" mechanisms developed for the AUV, Environmental Sample Processor, and other platforms in order to reduce the chance of the target organism escaping the gulper. There could be better filtration methods combined with preservation in order to increase the number sampled.

Last updated: Dec. 04, 2013