The Influence of Diel Vertical Migration on Krill Recruitment to Monterey Bay

Sarah CarrSummer Internship Project

Monterey Bay Aquarium Research InstituteMentor: Francisco Chavez and Tim Pennington

Background

• Using coupled biological-physical model• Physical model:

– ROMS circulation model (UCLA) used to generate current velocity fields of Monterey Bay region

• Coupled model:– Krill (E. pacifica) modeled as Lagrangian drifters

with diel vertical migration (DVM)– Idealized scenarios (passive and idealized DVM)

applicable to other organisms

ROMS Setup

• Grid:– 1.6 km resolution near Monterey Bay– 5 km resolution regionally– Variable vertical resolution (20 sigma levels)

• Driver: Coamps/Quickscat blended wind product

• Time: October 1999 - September 2000

• “Offline” Model Runs: ROMS velocity fields recorded 2X daily and averaged

Grids and Sample Model Output

5 km resolution 1.6 km resolution

Experimental Design• Behaviors

– Passive– Set DVM

• Swimming speed = 50, 100, 200, 300 m/hr (0.01 - 0.08 m/s)

• Vertical velocity = Model vertical velocity + Swimming speed

– Ontogenetic changes in DVM capacity of E. pacifica

Experimental Design

• Release locations:– Horizontal

• 10 krill sampling locations in Monterey Bay

– Vertical• Passive- Surface,

50, 100, 200, 300 m

• All DVM- Surface

Experimental Design• Release times:

– Daily at midnight

– 3 seasons • Upwelling (March- May)

• Oceanic (August-October)

• Davidson (November-January)

• Duration of tracking:– Idealized Behaviors- 20

days

– Krill- ~ 6 mo.

Average alongshore current velocity at the M1 mooring. Figure from Chavez et al. 2002.

Results: Model Sensitivity

• Starting Location• Starting Time:

– Hour

– Day

– Season

• Starting Depth• Behavior

Note: The following results are for particles started at these locations on six consecutive days in January and July 2000.

Temperature/Velocity Fields at Start of Simulations

Sensitivity to Start Time: Season

Sensitivity to Behavior

Sensitivity to Initial Depth-

July 2000

Suggestions?

• Experimental design:– Behavior

– Release locations (H,V)

– Release time

– Duration of tracking

• Visualization– Trajectories (2D, 3D)

– Particle Density