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Sargassum

Linking habitat to recruitment: Evaluating the importance of pelagic Sargassum to fisheries management in the Gulf of Mexico

This project evaluated the importance of sargassum as a nursery habitat for fish in the northern Gulf of Mexico.

Figure showing potential locations of Sargassum collection (red circles). Locations based on SEAMAP Plankton survey.

From the seminar “Linking habitat to recruitment: Evaluating the importance of pelagic Sargassum to fisheries management in the Gulf of Mexico” 
Presenter: Dr. Frank Hernandez, University of Southern Mississippi

Other Resources

The Team: Frank Hernandez (Lead Investigator, The University of Southern Mississippi, frank.hernandez@usm.edu), Chuanmin Hu (University of South Florida), Kevin Dillon (The University of Southern Mississippi), Glenn Zapfe (NOAA), and Walter Ingram (NOAA)

Technical Monitor: Mandy Karnauskas (mandy.karnauskas@noaa.gov)

Federal Program Officer/Point of Contact: Frank Parker (frank.parker@noaa.gov)

This project began in June 2017 and will end in May 2022.

Award Amount: $1,770,853

Why it matters: Sargassum is thought to serve as nursery habitat for recreationally and commercially important fishes in the Gulf of Mexico, such as gray triggerfish and mahi mahi. However, information about the nursery function of Sargassum for juvenile life stages of these fishes is lacking, and managers know little about the environmental factors that drive variability in Sargassum abundance and distribution.

Project Outcome: For this project we used field surveys, remote sensing, and modeling approaches to evaluate the nursery function and fisheries importance of Sargassum in a context useful for resource managers. Our team was successful in accomplishing the goals and objectives of this project. We generated maps of Sargassum distribution and biomass for the Gulf of Mexico, and described Sargassum interannual variability using a time series of remote sensing observations. In doing so we identified two potential “sources” of Sargassum for the Gulf of Mexico (western Gulf of Mexico, northwest Caribbean), and characterized the influence of eddies and frontal regions in determining Sargassum distribution. We collected in situ observations during four 9-day research cruises in the northern Gulf of Mexico, including a suite of environmental data and samples (e.g., nutrients, fishes, invertebrates, Sargassum) for analyses. 

Summary of Outcome: These data were used to quantify spatial and temporal patterns in Sargassum-associated fish abundance, taxonomic richness, and diversity. Food web dynamics were described using traditional diet analyses for a suite of managed species (gray triggerfish, greater amberjack, lesser amberjack, almaco jack, and tripletail). Bulk stable isotope analyses and compound specific stable isotope analyses were used to further characterize trophic pathways associated with Sargassum communities. We developed Sargassum Abundance Indices (SAIs) at multiple temporal and spatial scales using time series of vessel-based and remote sensing observations of Sargassum, and compared these SAIs to estimates of gray triggerfish recruitment. Our deliverables are intended to assist with the management of fisheries resources, and we will provide deliverables as needed to relevant on-going (e.g., greater amberjack count) and planned (e.g., Gulf of Mexico gray triggerfish SEDAR) assessments. We also developed and made available maps of frontal locations in the Gulf of Mexico, which help understand distributions of Sargassum and other ecologically important organisms. Our deliverables have also informed management of protected species (sea turtles) and has the potential to inform coastal communities dealing with Sargassum beaching events.

  • Historical Sargassum maps at weekly and daily scales have been made available through USF’s Sargassum Watch System (SaWS)
  • Hugi, A. 2022. Trophic ecology of sailfish larvae in the Gulf of Mexico: an analysis of diet, prey availability, prey quality, and influences on larval growth. MS Thesis, University of Southern Mississippi. https://aquila.usm.edu/masters_theses/891
  • Lestrade, O. 2020. Microplastic abundance, distribution and impacts on Sargassum-associated juvenile fishes in the Gulf of Mexico. MS Thesis, University of Southern Mississippi. https://aquila.usm.edu/masters_theses/781
  • Lestrade, O., and F. Hernandez. 2021. NOAA RESTORE Science Program: linking habitat to recruitment: evaluating the importance of pelagic sargassum to fisheries management in the Gulf of Mexico: microplastic concentration and ingestion in the Northern Gulf of Mexico, 2017-07-20 to 2019-06-04 (NCEI Accession 0232040). NOAA National Centers for Environmental Information. Dataset
  • Louisiana Universities Marine Consortium. 2022. Point Sur 1804, Gulfport, Mississippi, 2017-07-20 to 2017-07-28. Rolling Deck to Repository. Dataset
  • Louisiana Universities Marine Consortium. 2022. Point Sur 1826, Gulfport, Mississippi, 2018-05-30 to 2018-06-06. Rolling Deck to Repository. Dataset
  • Louisiana Universities Marine Consortium. 2020. Point Sur 1903, Gulfport, Mississippi, 2018-07-08 to 2018-07-17. Rolling Deck to Repository. Dataset
  • Louisiana Universities Marine Consortium. 2020. Point Sur 1922, Gulfport, Mississippi, 2019-05-28 to 2019-06-05. Rolling Deck to Repository. Dataset
  • Stachowiak, C. 2020. Assessing the nursery-role function of pelagic Sargassum for juvenile fishes in the northern Gulf of Mexico. MS Thesis, University of Southern Mississippi. https://aquila.usm.edu/masters_theses/786
  • Temperature and ocean color data products (e.g., chlorophyll concentration) at daily and weekly scales for the Gulf of Mexico have been made available through USF’s Virtual Antenna System
  • Wang, M. 2018. Spatial and temporal distributions of pelagic Sargassum in the Intra-Americas Sea and Atlantic Ocean. PhD Dissertation, University of South Florida. https://digitalcommons.usf.edu/etd/7716
  • Wang, M., C. Hu, and B. Barnes. 2019. Sargassum density and coverage using Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data from 2001-01-01 to 2018-12-31 (NCEI Accession 0190272). NOAA National Centers for Environmental Information. Dataset
  • Zhang, Y., and C. Hu. 2021. Data from: Ocean temperature and color frontal zones in the Gulf of Mexico: Where, when, and why. Mendeley Data. Dataset
Roberts, K.E., Garrison, L.P., Ortega-Ortiz, J., Hu, C., Zhang, Y., Sasso, C.R., Lamont, M., and Hart, K.M. (2022). The influence of satellite-derived environmental and oceanographic parameters on marine turtle time at surface in the Gulf of Mexico. Remote Sensing, 14, 4534. https://doi.org/10.3390/rs14184534
 
Putman, N.F. and Hu, C. (2022). Sinking Sargassum. Geophysical Research Letters, 49, e2022GL100189. https://doi.org/10.1029/2022GL100189
 
 
 
 
 
 
 
 
 
 
 

Take a look at the Weedlines blog for photos and updates from the project team.