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Research Spending & Results

Award Detail

Awardee:UNIVERSITY OF SAN DIEGO
Doing Business As Name:University of San Diego
PD/PI:
  • Nathalie Reyns
  • (619) 260-4096
  • nreyns@sandiego.edu
Award Date:01/15/2014
Estimated Total Award Amount: $ 342,987
Funds Obligated to Date: $ 342,987
  • FY 2014=$342,987
Start Date:01/15/2014
End Date:12/31/2018
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: Nearshore larval transport: physical and biological processes
Federal Award ID Number:1357327
DUNS ID:064467962
Parent DUNS ID:064467962
Program:BIOLOGICAL OCEANOGRAPHY
Program Officer:
  • Michael Sieracki
  • (703) 292-7585
  • msierack@nsf.gov

Awardee Location

Street:5998 Alcala Park
City:San Diego
State:CA
ZIP:92110-2476
County:San Diego
Country:US
Awardee Cong. District:52

Primary Place of Performance

Organization Name:University of San Diego
Street:
City:
State:CA
ZIP:92110-2492
County:San Diego
Country:US
Cong. District:52

Abstract at Time of Award

Providing an award for this study will provide essential knowledge required for management of coastal resources. This study addresses near shore cross-shore larval transport processes that operate over wide geographic areas in open coast settings, namely larval transport by wave circulation / Stokes drift, and by internal tidal bores. Larval transport by wave circulation / Stokes drift is a ubiquitous process that has not been studied observationally, and it is not known how internal tidal bores deliver larvae to intertidal habitats. This project will examine near shore (region between 20 m depth and intertidal) physical and biological processes that account for the delivery of larvae to adult habitats. The study system in Southern California shares similarities with most other temperate areas and we will study marine taxa that are widely distributed and successful in a variety of environments. Intellectual Merit: Recent studies suggest that larval transport in the near shore zone plays a central role in larval dispersal and connectivity of shallow water species. These recent advances, however, have not been matched with process-oriented studies addressing circulation and behavioral processes at the appropriate temporal and spatial scales, and only a few larval transport mechanisms have been considered for near shore open coastlines. Recent advances in our understanding of hydrodynamic processes driving cross-shore flows and growing awareness of the importance of the processes to larval transport, however, make this study timely. The investigators hypothesize that a series of physical and biological events results in the delivery of invertebrate larvae to the intertidal habitat. These events include physical transport due to wave circulation / Stokes drift near the surface and internal tide circulation near the bottom, alteration of behavior for terminal larval stages, and larval use of "adaptive" behavioral responses to exploit event-dependent flows. Further, they suggest that the predominance of wave circulation / Stokes drift and internal tide circulation varies seasonally, with internal tidal bores important in spring/summer, when the water column is well-stratified, and wave circulation / Stokes drift more pervasive in fall/winter, coinciding with winter storms. The hypotheses in this study will be tested with estimates of physical transport, larval supply and settlement. These measurements will be combined with use of adaptive sampling to test the dependence of larval vertical distribution on changes in hydrodynamic conditions. Broader Impacts: Results from this study will have important ecological implications as wave circulation / Stokes drift and internal motions may represent critical and regular transport mechanisms for larvae of marine organisms that must return to near shore habitats to complete their life cycle, thereby impacting population connectivity and management strategies used by coastal planners (e.g., ecosystem-based fisheries management, placement of Marine Protected Areas). The investigators will disseminate their results to the public through lectures and the development of a website. Furthermore, this project has a strong educational component, involving undergraduate and/or graduate students from two institutions (WHOI and University of San Diego). The research will be integrated into courses taught by all co-PIs at their respective institutions, but an integral component of this research is to enhance student experiential learning with cutting-edge research experiences at USD (a liberal-arts university). Sampling as part of this project will be incorporated into a field-based Marine Community Ecology course for upper-division undergraduates and students will be required to participate in at least one research cruise. The investigators also plan to offer competitive undergraduate student stipends for summer research at USD. To disseminate results, participants will be required to participate in the annual Undergraduate Research Conference, highlighting student-faculty interactions held at USD.

Publications Produced as a Result of this Research

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J. Pineda, N. Reyns, S. Lentz "Reduced barnacle larval abundance and settlement in response to large-scale oceanic disturbances: temporal patterns, nearshore thermal stratification, and potential mechanisms" Limnology and Oceanography, v.63, 2018, p.2618-2629. doi:https://doi.org/10.1002/lno.10964 

M. Hagerty, N. Reyns, J. Pineda "Constrained nearshore larval distributions driven by thermal stratification" Marine Ecology Progress Series, v.595, 2018, p.105?122. doi:https://doi.org/10.3354/meps12561 

Pineda, Jesús and Reyns, Nathalie and Lentz, Steven J. "Reduced barnacle larval abundance and settlement in response to large-scale oceanic disturbances: Temporal patterns, nearshore thermal stratification, and potential mechanisms: Settlement during the ?Blob? and El Niño" Limnology and Oceanography, v.63, 2018, p.. doi:10.1002/lno.10964 Citation details  

Hagerty, ML and Reyns, N and Pineda, J "Constrained nearshore larval distributions and thermal stratification" Marine Ecology Progress Series, v.595, 2018, p.. doi:10.3354/meps12561 Citation details  


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.

What factors determine the abundance and fluctuations of marine bottom organisms? For a long time, it has been understood that identifying the processes that influence the young is key to answering this question. Thus, a fundamental question in marine science is how the larvae, or early life stages, of bottom marine organisms that develop in the ocean, are transported to nearshore coastal habitats to complete the life cycle. Such understanding is critical for understanding how populations fluctuate, for determining the placement of marine reserves, and for managing commercially important species such as crabs and lobsters. In the past, researchers have focused on how open-ocean offshore processes influence the distribution and transport of larvae of shallow water species. A series of studies during the last two decades indicate, however, that most larvae stay close to shallow water. Thus, an exclusive focus on offshore processes in the last few decades might have been misplaced.

To gain knowledge on the ocean currents affecting the larvae, their distribution near the shallow adult habitat, and to better understand the mechanisms responsible for larval transport to shore, we undertook a two-year (2014-2015) study to quantify the number of larvae in the water column at five stations within 1 km of shore. We also measured water temperature, currents, and wave height, and counted the number of barnacle larvae settling in nearshore intertidal habitats. Barnacle larvae serve as a good proxy for other species, as they have a similar life cycle to those of many bottom organisms.

Our study produced two significant findings, potentially breakthroughs. First, the separation between the minuscule larvae and the adult habitat was related to thermal stratification –the difference in temperature between surface and bottom waters. With larger differences, or greater stratification, the larvae were found closer to the shore. This is an intuitive result, because large temperature differences are associated with flows that reverse with depth, and it is known that larvae exploit these flows to control their distribution around the adult habitat. However, to our knowledge this is the first study that has resolved this issue. Second, we identified an area between offshore waters and the zone where the waves break where larvae accumulate, and that the abundance of larvae that settled on the shore is correlated with that in the ‘zone of accumulation’. This suggests that the processes that cause this area to grow or dissipate may control how many larvae are supplied to adult habitats, a significant finding.

All fieldwork and sample processing was conducted using facilities and resources at the University of San Diego (USD), a primarily undergraduate institution. This project had broad participation, providing research experiences and training for 12 undergraduate students, 6 graduate students, and 6 technicians. A Woods Hole Oceanographic Institution (WHOI) postdoctoral scholar completed research based on ideas spun from the grant. Two under-represented high school students conducted summer research, and two undergraduate Honors Theses were produced from this work, including a collaborative project that used DNA barcoding to identify fish eggs collected in our larval samples, and extended the scope of this research beyond invertebrate larvae. Two M.S. theses were completed resulting in three manuscripts with graduate student authors. Data collected in these projects were used to develop undergraduate curriculum at USD. We disseminated results widely, through presentations at national and international conferences, including those authored by undergraduate and graduate students, as well as though peer-reviewed publications.


 


Last Modified: 02/23/2019
Modified by: Nathalie Reyns

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