the influence of diel vertical migration on krill recruitment to monterey bay sarah carr summer...

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