Amino Acid Nitrogen Analysis of Green Sea Turtle Tissue ( Chelonia - - PowerPoint PPT Presentation

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Aug 27, 2023 245 likes •452 views

Amino Acid Nitrogen Analysis of Green Sea Turtle Tissue ( Chelonia mydas ): Testing Assumptions for Application to Field Studies 1 Garrett Lemons, 1 Rebecca Lewison, 2 Brian Popp 1 San Diego State University - San Diego, CA 2 University of Hawaii -

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1Garrett Lemons, 1Rebecca Lewison, 2Brian Popp

1 San Diego State University - San Diego, CA 2 University of Hawaii - Honolulu, HI

J. Stuart Haldan Foundation

Amino Acid Nitrogen Analysis of Green Sea Turtle Tissue (Chelonia mydas): Testing Assumptions for Application to Field Studies

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Complex life histories
Difficult to access

habitats

Highly migratory
Cryptic in nature

Methods of study?

Telemetry
Surveys
Stable Isotopes

Green turtles: challenging to study

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?

Diet? Duration? Habitat use?

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Arthur et al. (2008)

Δ Trophic interactions Δ Nutrient composition

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Analysis of δ15N

ENRICHMENT

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Global patterns of N2 fixation & denitrification N2 Fixation = ↓ δ15N Denitrification = ↑δ15N

N* map courtesy of Francisco Chavez

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Analysis of stable δ15N

Δδ15N

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Bulk vs. amino acid SIA

GLU PRO LYS THR ALA ISO PHE VAL

BULK δ15N CSIA δ15N

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δ15N analysis of amino acids

McClelland and Montoya (2002)

Trophic Source

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Using AA-CSIA we assume…

Trophic and source amino acids are the same

across taxa and tissue types.

Constants for equations, such as trophic

discrimination factors, are the same across taxa and tissues.

Turnover rates are based on previously

published bulk studie.

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Research questions

1. What are green turtle and tissue-specific

amino acids?

2. What are green turtle tissue specific Trophic

discrimination factors (TDFs)?

1. If above questions are validated, then we

need to understand what is the temporal framework or turnover rates for tissue?

TLx/y = (δ15NGlu – δ15NPhe – 3.4x/y)/(Δ x – Δ y) + 1

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Experiment

4 captive East Pacific green

turtles

Steady state determination
Diet switch to 15N depleted diet
Interval sampling of skin and

blood

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1. Green turtle-specific amino acids?

Δ15N (15N consumer – 15N diet ‰) Trophic Source plasma

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2.Trophic discrimination factors for plasma?

TrophicAAδ15N – SourceAAδ15N = TDF (‰) TrophicAA - SourceAA

C. Mydas

(‰)

McClelland and Montoya (2002)

(‰)

Chikaraishi et

al. (2009)

(‰)

Glu - Phe 6.59 6.4 7.6 Glu - Lys 5.92 5.1

Val - Phe

5.42 Val - Lys 4.66 2.6

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Days

SOURCE AAs

T2 T3 T4

3.Turnover rates for plasma?

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TROPHIC AAs

T4 T3 Glutamic acid N turnover Valine N turnover

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Summary

Successfully identified source and trophic AAs for

green turtle

Difference among taxa
Appropriate AA selection
Successfully determining TDFs for plasma and skin
Difference between tissue and animal
Preliminary N turnover in plasma
Temporal framework for tissues

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Significance

First validation for a marine megafauna
One isotope, more insight
Nutrient dynamics over large spatial scales
Advancing field application by testing

assumptions

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Acknowledgments

Stuart Haldan, and the J. Stuart Haldan charitable foundation
COAST Graduate research award
Ferris Travel student travel award
Research Assistants – Christina Coppenrath, Linda Duling
NOAA/SWFSC – J. Seminoff, Robin, Camryn, Joel, Erin
SDSU – Entire Lewison lab and committee members, Dr. Lai,
Dr. Schellenberg
University of Hawaii –Natalie Walsgrove, Cassie
Living Coast Discovery Center – Beth Sabiston, Ben Vallejos,

Lindsay Bradshaw, Gilberto

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