Long-Term Monitoring of In-Water Abundance of Juvenile Pelagic Loggerhead Sea Turtles (Caretta caretta): Population Trends in Relation to North Atlantic Oscillation and Nesting
Sea turtles have various life-stages, typically being oceanic foragers as juveniles while shifting to more coastal habitats as they mature. The present study focuses on the least studied and well known of these, the juvenile oceanic life stage for the loggerhead sea turtle, Caretta caretta. Loggerhe...
Published in: | Frontiers in Marine Science |
---|---|
Main Authors: | , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Frontiers Media S.A.
2022
|
Subjects: | |
Online Access: | https://doi.org/10.3389/fmars.2022.877636 https://doaj.org/article/7216c7d844c5497fa49b8a9f7fb5f92a |
id |
ftdoajarticles:oai:doaj.org/article:7216c7d844c5497fa49b8a9f7fb5f92a |
---|---|
record_format |
openpolar |
spelling |
ftdoajarticles:oai:doaj.org/article:7216c7d844c5497fa49b8a9f7fb5f92a 2023-05-15T17:28:26+02:00 Long-Term Monitoring of In-Water Abundance of Juvenile Pelagic Loggerhead Sea Turtles (Caretta caretta): Population Trends in Relation to North Atlantic Oscillation and Nesting Thomas Dellinger Vladimir Zekovic Marko Radeta 2022-07-01T00:00:00Z https://doi.org/10.3389/fmars.2022.877636 https://doaj.org/article/7216c7d844c5497fa49b8a9f7fb5f92a EN eng Frontiers Media S.A. https://www.frontiersin.org/articles/10.3389/fmars.2022.877636/full https://doaj.org/toc/2296-7745 2296-7745 doi:10.3389/fmars.2022.877636 https://doaj.org/article/7216c7d844c5497fa49b8a9f7fb5f92a Frontiers in Marine Science, Vol 9 (2022) sea turtles wavelet transformation El Niño NAO in-water abundance oceanic life stage Science Q General. Including nature conservation geographical distribution QH1-199.5 article 2022 ftdoajarticles https://doi.org/10.3389/fmars.2022.877636 2022-12-31T01:57:21Z Sea turtles have various life-stages, typically being oceanic foragers as juveniles while shifting to more coastal habitats as they mature. The present study focuses on the least studied and well known of these, the juvenile oceanic life stage for the loggerhead sea turtle, Caretta caretta. Loggerhead sea turtles remain threatened by fisheries and their distribution and habitat change in the North Atlantic remains poorly understood. After hatching and swimming out to sea, turtles spend 7 or more years in the pelagic life stage. Madeira Island has an advantage of being situated in the middle of the North Atlantic developmental habitat for loggerheads originating both from the US, as well as, from Cape Verde and other mixed source rookeries. Understanding the demographics of this oceanic life stage has been described as a research priority. We here present a population trendline and the abundance variation of oceanic stage loggerheads, measured at a single geographic spot in Madeiran waters, over the period of 15 years. We find that the observed loggerhead distribution results from combined effects of physical and biological processes within the North Atlantic. We explore physical phenomena that influence abundance variability, and find that oscillations in climate affect the turtle migrations, as does the population recruitment from the nesting rookeries. For this, we use novel cost-effective census methods that take advantage of platforms of opportunity from the blue ecotourism industry. To study the time series and their correlations we use spectral analysis, a method not commonly used in traditional population assessments, including Wavelet and Fourier Transformations (WT and FFT), and Digital Signal Processing (DSP) techniques. A strong anti-correlation between sea turtle sightings and North Atlantic Oscillation seasonal components was found, which implies that loggerhead sea turtles are less abundant during positive NAO phases. We also detected long period trends in the sighting data which we relate to La ... Article in Journal/Newspaper North Atlantic North Atlantic oscillation Directory of Open Access Journals: DOAJ Articles Frontiers in Marine Science 9 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
sea turtles wavelet transformation El Niño NAO in-water abundance oceanic life stage Science Q General. Including nature conservation geographical distribution QH1-199.5 |
spellingShingle |
sea turtles wavelet transformation El Niño NAO in-water abundance oceanic life stage Science Q General. Including nature conservation geographical distribution QH1-199.5 Thomas Dellinger Vladimir Zekovic Marko Radeta Long-Term Monitoring of In-Water Abundance of Juvenile Pelagic Loggerhead Sea Turtles (Caretta caretta): Population Trends in Relation to North Atlantic Oscillation and Nesting |
topic_facet |
sea turtles wavelet transformation El Niño NAO in-water abundance oceanic life stage Science Q General. Including nature conservation geographical distribution QH1-199.5 |
description |
Sea turtles have various life-stages, typically being oceanic foragers as juveniles while shifting to more coastal habitats as they mature. The present study focuses on the least studied and well known of these, the juvenile oceanic life stage for the loggerhead sea turtle, Caretta caretta. Loggerhead sea turtles remain threatened by fisheries and their distribution and habitat change in the North Atlantic remains poorly understood. After hatching and swimming out to sea, turtles spend 7 or more years in the pelagic life stage. Madeira Island has an advantage of being situated in the middle of the North Atlantic developmental habitat for loggerheads originating both from the US, as well as, from Cape Verde and other mixed source rookeries. Understanding the demographics of this oceanic life stage has been described as a research priority. We here present a population trendline and the abundance variation of oceanic stage loggerheads, measured at a single geographic spot in Madeiran waters, over the period of 15 years. We find that the observed loggerhead distribution results from combined effects of physical and biological processes within the North Atlantic. We explore physical phenomena that influence abundance variability, and find that oscillations in climate affect the turtle migrations, as does the population recruitment from the nesting rookeries. For this, we use novel cost-effective census methods that take advantage of platforms of opportunity from the blue ecotourism industry. To study the time series and their correlations we use spectral analysis, a method not commonly used in traditional population assessments, including Wavelet and Fourier Transformations (WT and FFT), and Digital Signal Processing (DSP) techniques. A strong anti-correlation between sea turtle sightings and North Atlantic Oscillation seasonal components was found, which implies that loggerhead sea turtles are less abundant during positive NAO phases. We also detected long period trends in the sighting data which we relate to La ... |
format |
Article in Journal/Newspaper |
author |
Thomas Dellinger Vladimir Zekovic Marko Radeta |
author_facet |
Thomas Dellinger Vladimir Zekovic Marko Radeta |
author_sort |
Thomas Dellinger |
title |
Long-Term Monitoring of In-Water Abundance of Juvenile Pelagic Loggerhead Sea Turtles (Caretta caretta): Population Trends in Relation to North Atlantic Oscillation and Nesting |
title_short |
Long-Term Monitoring of In-Water Abundance of Juvenile Pelagic Loggerhead Sea Turtles (Caretta caretta): Population Trends in Relation to North Atlantic Oscillation and Nesting |
title_full |
Long-Term Monitoring of In-Water Abundance of Juvenile Pelagic Loggerhead Sea Turtles (Caretta caretta): Population Trends in Relation to North Atlantic Oscillation and Nesting |
title_fullStr |
Long-Term Monitoring of In-Water Abundance of Juvenile Pelagic Loggerhead Sea Turtles (Caretta caretta): Population Trends in Relation to North Atlantic Oscillation and Nesting |
title_full_unstemmed |
Long-Term Monitoring of In-Water Abundance of Juvenile Pelagic Loggerhead Sea Turtles (Caretta caretta): Population Trends in Relation to North Atlantic Oscillation and Nesting |
title_sort |
long-term monitoring of in-water abundance of juvenile pelagic loggerhead sea turtles (caretta caretta): population trends in relation to north atlantic oscillation and nesting |
publisher |
Frontiers Media S.A. |
publishDate |
2022 |
url |
https://doi.org/10.3389/fmars.2022.877636 https://doaj.org/article/7216c7d844c5497fa49b8a9f7fb5f92a |
genre |
North Atlantic North Atlantic oscillation |
genre_facet |
North Atlantic North Atlantic oscillation |
op_source |
Frontiers in Marine Science, Vol 9 (2022) |
op_relation |
https://www.frontiersin.org/articles/10.3389/fmars.2022.877636/full https://doaj.org/toc/2296-7745 2296-7745 doi:10.3389/fmars.2022.877636 https://doaj.org/article/7216c7d844c5497fa49b8a9f7fb5f92a |
op_doi |
https://doi.org/10.3389/fmars.2022.877636 |
container_title |
Frontiers in Marine Science |
container_volume |
9 |
_version_ |
1766121098530783232 |