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Lamont MM, Slone D, Reid JP, Butler SM, Alday J. Deep vs shallow: GPS tags reveal a dichotomy in movement patterns of loggerhead turtles foraging in a coastal bay. MOVEMENT ECOLOGY 2024; 12:40. [PMID: 38816732 PMCID: PMC11140867 DOI: 10.1186/s40462-024-00480-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Accepted: 05/21/2024] [Indexed: 06/01/2024]
Abstract
BACKGROUND Individual variation in movement strategies of foraging loggerhead turtles have been documented on the scale of tens to hundreds of kilometers within single ocean basins. Use of different strategies among individuals may reflect variations in resources, predation pressure or competition. It is less common for individual turtles to use different foraging strategies on the scale of kilometers within a single coastal bay. We used GPS tags capable of back-filling fine-scale locations to document movement patterns of loggerhead turtles in a coastal bay in Northwest Florida, U.S.A. METHODS Iridium-linked GPS tags were deployed on loggerhead turtles at a neritic foraging site in Northwest Florida. After filtering telemetry data, point locations were transformed to movement lines and then merged with the original point file to define travel paths and assess travel speed. Home ranges were determined using kernel density function. Diurnal behavioral shifts were examined by examining turtle movements compared to solar time. RESULTS Of the 11 turtles tagged, three tracked turtles remained in deep (~ 6 m) water for almost the entire tracking period, while all other turtles undertook movements from deep water locations, located along edges and channels, to shallow (~ 1-2 m) shoals at regular intervals and primarily at night. Three individuals made short-term movements into the Gulf of Mexico when water temperatures dropped, and movement speeds in the Gulf were greater than those in the bay. Turtles exhibited a novel behavior we termed drifting. CONCLUSIONS This study highlighted the value provided to fine-scale movement studies for species such as sea turtles that surface infrequently by the ability of these GPS tags to store and re-upload data. Future use of these tags at other loggerhead foraging sites, and concurrent with diving and foraging data, would provide a powerful tool to better understand fine-scale movement patterns of sea turtles.
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Affiliation(s)
- Margaret M Lamont
- U.S. Geological Survey, Wetland and Aquatic Research Center, Gainesville, FL 32653, USA.
| | - Daniel Slone
- U.S. Geological Survey, Wetland and Aquatic Research Center, Gainesville, FL 32653, USA
| | - James P Reid
- U.S. Geological Survey, Wetland and Aquatic Research Center, Gainesville, FL 32653, USA
| | - Susan M Butler
- U.S. Geological Survey, Wetland and Aquatic Research Center, Gainesville, FL 32653, USA
| | - Joseph Alday
- U.S. Geological Survey, Wetland and Aquatic Research Center, Gainesville, FL 32653, USA
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Stankovic M, Panyawai J, Khanthasimachalerm N, Prathep A. National assessment and variability of blue carbon in seagrass ecosystems in Thailand. MARINE POLLUTION BULLETIN 2023; 197:115708. [PMID: 37951123 DOI: 10.1016/j.marpolbul.2023.115708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 09/21/2023] [Accepted: 10/19/2023] [Indexed: 11/13/2023]
Abstract
Seagrass ecosystems are important organic carbon (Corg) sinks with great potential to contribute to climate change mitigation strategies. However, the high spatial and temporal variability is a barrier to the accurate assessment of national Corg stocks. This study provides a national assessment of Corg within seagrass meadows, including spatial and temporal variations. The highest Corg stocks were within mangrove-associated (44.3 ± 8.27 Mg ha-1), while near-surface sediments were highest in reef-associated meadows (10.20 ± 3.69 Mg ha-1). Regionally, the highest stocks were in the Upper Andaman coast in monospecific meadows (51.7 ± 7.14 Mg ha-1). Corg stocks in near-surface sediments were significantly different across historical trends (p < 0.001), with the highest stocks in stable meadows (9.28 ± 3.39 Mg ha-1). The national Corg stock within seagrass meadows sediment was 40.45 ± 11.59 Mg C ha-1. The results of this study highlighted the complexity of blue carbon in seagrass meadows and the associated impacts on national Corg assessments, carbon accounting, and conservation strategies.
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Affiliation(s)
- Milica Stankovic
- Excellence Center for Biodiversity of Peninsular Thailand, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand; Field Marine Station, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand.
| | - Janmanee Panyawai
- Division of Biological Science, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand
| | - Nattacha Khanthasimachalerm
- Division of Biological Science, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand
| | - Anchana Prathep
- Excellence Center for Biodiversity of Peninsular Thailand, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand; Division of Biological Science, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand
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Hill VJ, Zimmerman RC, Bissett P, Kohler D, Schaeffer B, Coffer M, Li J, Islam KA. Impact of Atmospheric Correction on Classification and Quantification of Seagrass Density from WorldView-2 Imagery. REMOTE SENSING 2023; 15:1-25. [PMID: 38362160 PMCID: PMC10866308 DOI: 10.3390/rs15194715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
Mapping the seagrass distribution and density in the underwater landscape can improve global Blue Carbon estimates. However, atmospheric absorption and scattering introduce errors in space-based sensors' retrieval of sea surface reflectance, affecting seagrass presence, density, and above-ground carbon (AGC seagrass ) estimates. This study assessed atmospheric correction's impact on mapping seagrass using WorldView-2 satellite imagery from Saint Joseph Bay, Saint George Sound, and Keaton Beach in Florida, USA. Coincident in situ measurements of water-leaving radiance (L W ), optical properties, and seagrass leaf area index (LAI) were collected. Seagrass classification and the retrieval of LAI were compared after empirical line height (ELH) and dark-object subtraction (DOS) methods were used for atmospheric correction. DOS left residual brightness in the blue and green bands but had minimal impact on the seagrass classification accuracy. However, the brighter reflectance values reduced LAI retrievals by up to 50% compared to ELH-corrected images and ground-based observations. This study offers a potential correction for LAI underestimation due to incomplete atmospheric correction, enhancing the retrieval of seagrass density and above-ground Blue Carbon from WorldView-2 imagery without in situ observations for accurate atmospheric interference correction.
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Affiliation(s)
- Victoria J. Hill
- Department of Ocean and Earth Sciences, Old Dominion University, Norfolk, VA 23529, USA
| | - Richard C. Zimmerman
- Department of Ocean and Earth Sciences, Old Dominion University, Norfolk, VA 23529, USA
| | - Paul Bissett
- Eathon Intelligence LLC, 2210 US Hwy 301 S, Suite 100, Tampa, FL 33619, USA
| | - David Kohler
- Trimble, Inc., 10368 Westmoor Drive, Westminster, CO 80021, USA
| | - Blake Schaeffer
- Office of Research and Development, U.S. Environmental Protection Agency, Durham, NC 27709, USA
| | - Megan Coffer
- Global Science & Technology, Inc., Greenbelt, MD 20770, USA
- NOAA/NESDIS Center for Satellite Applications and Research, College Park, MD 20740, USA
| | - Jiang Li
- Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, VA 23529, USA
| | - Kazi Aminul Islam
- Department of Computer Science, Kennesaw State University, Marietta, GA 30060, USA
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Coffer MM, Graybill DD, Whitman PJ, Schaeffer BA, Salls WB, Zimmerman RC, Hill V, Lebrasse MC, Li J, Keith DJ, Kaldy J, Colarusso P, Raulerson G, Ward D, Kenworthy WJ. Providing a framework for seagrass mapping in United States coastal ecosystems using high spatial resolution satellite imagery. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 337:117669. [PMID: 36966636 PMCID: PMC10622156 DOI: 10.1016/j.jenvman.2023.117669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 02/08/2023] [Accepted: 03/02/2023] [Indexed: 06/18/2023]
Abstract
Seagrasses have been widely recognized for their ecosystem services, but traditional seagrass monitoring approaches emphasizing ground and aerial observations are costly, time-consuming, and lack standardization across datasets. This study leveraged satellite imagery from Maxar's WorldView-2 and WorldView-3 high spatial resolution, commercial satellite platforms to provide a consistent classification approach for monitoring seagrass at eleven study areas across the continental United States, representing geographically, ecologically, and climatically diverse regions. A single satellite image was selected at each of the eleven study areas to correspond temporally to reference data representing seagrass coverage and was classified into four general classes: land, seagrass, no seagrass, and no data. Satellite-derived seagrass coverage was then compared to reference data using either balanced agreement, the Mann-Whitney U test, or the Kruskal-Wallis test, depending on the format of the reference data used for comparison. Balanced agreement ranged from 58% to 86%, with better agreement between reference- and satellite-indicated seagrass absence (specificity ranged from 88% to 100%) than between reference- and satellite-indicated seagrass presence (sensitivity ranged from 17% to 73%). Results of the Mann-Whitney U and Kruskal-Wallis tests demonstrated that satellite-indicated seagrass percentage cover had moderate to large correlations with reference-indicated seagrass percentage cover, indicative of moderate to strong agreement between datasets. Satellite classification performed best in areas of dense, continuous seagrass compared to areas of sparse, discontinuous seagrass and provided a suitable spatial representation of seagrass distribution within each study area. This study demonstrates that the same methods can be applied across scenes spanning varying seagrass bioregions, atmospheric conditions, and optical water types, which is a significant step toward developing a consistent, operational approach for mapping seagrass coverage at the national and global scales. Accompanying this manuscript are instructional videos describing the processing workflow, including data acquisition, data processing, and satellite image classification. These instructional videos may serve as a management tool to complement field- and aerial-based mapping efforts for monitoring seagrass ecosystems.
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Affiliation(s)
- Megan M Coffer
- Oak Ridge Institute for Science and Education, U.S. Environmental Protection Agency, Office of Research and Development, Durham, NC, USA; Global Science & Technology, Inc., Greenbelt, MD, USA.
| | - David D Graybill
- Oak Ridge Institute for Science and Education, U.S. Environmental Protection Agency, Office of Research and Development, Durham, NC, USA
| | - Peter J Whitman
- Oak Ridge Institute for Science and Education, U.S. Environmental Protection Agency, Office of Research and Development, Durham, NC, USA
| | - Blake A Schaeffer
- U.S. Environmental Protection Agency, Office of Research and Development, Durham, NC, USA
| | - Wilson B Salls
- U.S. Environmental Protection Agency, Office of Research and Development, Durham, NC, USA
| | - Richard C Zimmerman
- Department of Earth & Ocean Sciences, Old Dominion University, Norfolk, VA, USA
| | - Victoria Hill
- Department of Earth & Ocean Sciences, Old Dominion University, Norfolk, VA, USA
| | - Marie Cindy Lebrasse
- Oak Ridge Institute for Science and Education, U.S. Environmental Protection Agency, Office of Research and Development, Durham, NC, USA; Department of Marine, Earth and Atmospheric Sciences, North Carolina State University, Raleigh, NC, USA
| | - Jiang Li
- Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, VA, USA
| | - Darryl J Keith
- U.S. Environmental Protection Agency, Office of Research and Development, Narragansett, RI, USA
| | - James Kaldy
- U.S. Environmental Protection Agency, Office of Research and Development, Newport, OR, USA
| | - Phil Colarusso
- U.S. Environmental Protection Agency, Region 1, Boston, MA, USA
| | | | - David Ward
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
| | - W Judson Kenworthy
- Department of Biology and Marine Biology, University of North Carolina, Wilmington, NC, USA
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