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Award Detail

Awardee:UNIVERSITY OF CALIFORNIA, DAVIS
Doing Business As Name:University of California-Davis
PD/PI:
  • Steven G Morgan
  • (707) 875-1920
  • sgmorgan@ucdavis.edu
Co-PD(s)/co-PI(s):
  • John L Largier
Award Date:07/18/2013
Estimated Total Award Amount: $ 629,277
Funds Obligated to Date: $ 629,277
  • FY 2013=$629,277
Start Date:09/01/2013
End Date:08/31/2018
Transaction Type:Grant
Agency:NSF
Awarding Agency Code:4900
Funding Agency Code:4900
CFDA Number:47.050
Primary Program Source:040100 NSF RESEARCH & RELATED ACTIVIT
Award Title or Description:Collaborative Research: Field test of larval behavior on transport and connectivity in an upwelling regime
Federal Award ID Number:1334448
DUNS ID:047120084
Parent DUNS ID:071549000
Program:BIOLOGICAL OCEANOGRAPHY
Program Officer:
  • David Garrison
  • (703) 292-8582
  • dgarriso@nsf.gov

Awardee Location

Street:OR/Sponsored Programs
City:Davis
State:CA
ZIP:95618-6134
County:Davis
Country:US
Awardee Cong. District:03

Primary Place of Performance

Organization Name:UCD Bodega Marine Lab
Street:2099 Westside Rd
City:Bodega Bay
State:CA
ZIP:94923-0247
County:Bodega Bay
Country:US
Cong. District:02

Abstract at Time of Award

Background: The majority of larvae of coastal marine species are planktonic and generally weak swimmers. Thus, they are thought to be dispersed widely by coastal currents. However, there is accumulating evidence that their behavior can strongly influence their transport: some remain within estuaries, while others make true migrations between adult and larval habitats, even out to the edge of the continental shelf and back. Rates and directions of larval transport are thought to be determined largely by the timing, duration, and amplitude of vertical migrations and the mean depth that larvae occupy in stratified flows. The PIs propose to provide one of the first direct tests of how behavior affects across-shelf and alongshore transport using biomimetic drifters. The study will be conducted in a region of persistent upwelling, where strong currents are widely believed to overwhelm larval swimming and limit recruitment to adult populations. Intellectual merit: Knowledge of underlying mechanisms regulating larval transport is central to understanding ecology and evolution in the sea and anticipating the impacts of climate change on marine populations and communities. The proposed research will provide the first experimental field-test of how larval behavior affects the rates, directions and distances of transport and population connectivity in an upwelling regime. The PIs will test three hypotheses: 1. Residence below the wind-driven surface layer and vertical migrations below that layer keep larvae closer to shore compared to residence in the surface layer or larvae without depth preferences and vertical migration. 2. Residence at depth enhances northward transport near shore, and vertical migration leads to decreased alongshore mean displacement but increased variance for a group. 3. Depth preferences and vertical migrations have pronounced effects on retention and transport of plankton in upwelling regions. The study will compare direct measurements from mimetic drifters with observed and modeled cross-shelf larval distributions, and with modeled alongshore transport. Results will be broadly applicable to upwelling regimes along the western margins of continents, and the approach can be applied to non-upwelling systems throughout the world. Broader impacts: The proposed research will support a graduate student and six undergraduates at two institutions. It will also provide volunteer research opportunities for college and high school students with diverse backgrounds and for members of the public. The research will be included in college courses taught by the PIs, and will be added to websites and visitor displays at the PIs' two institutions. Results will be disseminated to science teams managing and designing Marine Protected Area networks through the PIs' advisory associations.


Project Outcomes Report

Disclaimer

This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.

This project was two-pronged.  The biological oceanography portion (based at Bodega Marine Laboratory) addressed how transport of larvae in the ocean is affected by their behavior.  The technological aspect addresses a roadblock to studying transport of living larvae in the ocean:  the impossibility of tracking them. We created a “robot larva” that mimics larval behaviors and resultant drift, and it can be tracked.

Intellectual Merit

How microscopic larvae are transported by ocean currents is no small matter. Most marine invertebrates, and even fishes, reproduce by releasing tiny offspring into the surrounding water.  They typically are weak swimmers while small, and go where the water is going. To become part of the next generation, they must be transported to appropriate habitats to take on adult forms and ecological roles. Whether they succeed has huge implications for choosing the location and size of Marine Protected Areas as sources to repopulate depleted or overfished habitats and for fisheries management -- does larval mixing make this a single population, or several isolated stocks?  Larval transport also affects how fast invasive species spread and how resilient species are to changing climate—can they move as fast as physical zones are moving? 

What if the water into which larvae were released is not going where they need to go? Water motion isn’t homogeneous, and behavior gives even weakly swimming larvae options to affect transport by migrating vertically into different layers of water moving at different velocities or directions.

On the technological side of the project, we developed a novel biomimetic instrument: the Autonomous Behaving Lagrangian Explorer (ABLE) to serve as a “trackable robotic larva.”  They sense their physical microenvironment, log the data, and use the data to dynamically calculate the target depth toward which they migrate according to a behavioral model based on real larvae. Multiple tracking modalities permitted recovery even in rough sea states: a pinger while submerged, LED and VHF beacons while at the surface and GPS coordinates sent to satellites during brief excursions to the surface. They run for at least 3 weeks on a battery charge (similar to the larval lifetime of many species.) They are optimized for simplicity and low cost (<$1K each) since drifter studies require that numerous replicates be deployed at once. ABLEs were further refined as ocean experiments subjected them to challenges they had not faced in a tank or pool. 

On the biological oceanography side, field experiments were conducted at the Bodega Marine Laboratory, in an upwelling region on the central California coast, because larval transport is especially important in such biological hotspots. Prevailing winds drive surface waters offshore, and draw colder, nutrient-rich water from the depths into the sunlit surface layers. This supports some of the highest levels of plant (phytoplankton) and hence animal productivity in the world’s oceans. In upwelling currents, larvae that remain near the surface are expected to be swept downwind and offshore (southwest), carried out to sea and lost. In contrast, observations show that they typically remain within a few km of the adult habitats where they were released. This could not occur if they were remaining at a fixed depth; vertical migratory behavior must be involved.

Broader Impacts

To assess effects of vertical migratory behaviors, ABLEs were released at various sites, programmed with theoretical or observed larval behavioral patterns and tracked for 1-2 days.  Several hypotheses were tested and ABLE trajectories were consistent with each.

1. Larvae that remain near-surface during upwelling would be transported SW and offshore with surface waters. ABLEs at 2 m went in that direction at several km/day. 

2. When upwelling stops, as denser upwelled water sloshes back down (the system “relaxes,”) larvae that remain near the surface would be transported northward and inshore. ABLEs at 2 m went north at several km/day and were recovered close to shore.

3. Larvae that remain near the bottom would be transported shorter distances under either upwelling or relaxation conditions. ABLEs remaining at 16 m bore this out.

4. Larvae that perform daily vertical migrations (up at night, deep during the day) would experience transport intermediate between that of near-surface and near-bottom larvae. The distance they were transported would be particularly affected by wind speeds at night, when they were in the wind-driven surface layer. ABLEs migrating between 2 m and 16 m showed intermediate and highly variable speed of transport.

Broader Impacts

The results from field experiments are directly relevant to resource and MPA management.    Collaborators, technicians and students have been trained to use this novel technology. The demonstration that ABLEs can address transport questions in many coastal and estuarine systems has generated interest from other potential users and manufacturers, and we look forward to new areas of inquiry opening. Exposure of the project in various articles, particularly the award-winning PBS “Science Friday” spot, generated public interest in science.

 


Last Modified: 12/17/2018
Modified by: Steven G Morgan

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