Nutritional deposition by nesting Loggerhead sea turtles enhances dune resilience
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Transcript of Nutritional deposition by nesting Loggerhead sea turtles enhances dune resilience
Nutri&onal deposi&on by nes&ng Loggerhead sea turtles (Care%a care%a) enhances dune resilience
Jared Chrisp
Outline
• Objec&ves
• Processes that influence dune ecosystems
• Experiment procedures
• Previous year results
Goals and Objec&ves
1. Quan&fy the amount of nutrients, in the form of unhatched eggs and residual biomass, that remain aGer a nest hatches
2. Determine if Sea oats (Uniola paniculata) gain mass by leaching nutrients from eggs
The objec&ve of this experiment is to determine and create an index for the number of nests needed on the beaches of Bald Head Island to be significant enough to impact dune health.
Where do the nutrients come
from?
• Thousands of miles every three years
• LiSle feeding at nes&ng grounds
• Nutrients not otherwise available
Source: seaturtle.org
Pathways for Nutrient Transfer
Hatched Eggs Unhatched Eggs
Successfully reach ocean
Consumed by
predators
Residual chorioallantoic
fluid and egg shells
Trapped in nest
Consumed by nest
predators
Nutrients absorbed by
plants
Made available to decomposers
Energy lost as metabolic heat
Sea Oats (Uniola paniculata)
• Most prominent dune vegeta&on
• Prolific root structure
• Stabilize dune systems
• Low nutrient condi&ons
Sea Oat Experiment
• Controlled growth
– Two growth mediums
– Biomass and nitrogen
– Root to shoot ra&os
– Root migra&on?
Sampling and Techniques
• One unhatched egg
• One egg shell
• Percentage of nests with root intrusions
• Number of hatched and unhatched eggs
Lab Procedures
• Composi&on of essen&al elements in eggs and shells:
– calories – nitrogen – lipids – moisture – ash content
2012 Analysis
• Expansion factors: – Unhatched eggs per nest – Hatched egg shells per nest – Average mass of eggs
Final Des&na&on of Eggs*
*Final des&na&on of the total eggs (n = 2377) for all nests (n = 20) along the 4 mile stretch of Bald Head Island’s east facing beach.
Total Percent of total eggs
Hatched 2115 89%
Emerge from nest 1797 76% Live in nest 318 14% Dead in nest 2 > 1%
Unhatched 262 11%
Unfertilized 224 9% Predated 38 2%
2012 Results
• Egg Mass (g) – x̄ = 35.33 ± 0.454 – Shell ~1.43 g
• Eggs per Nest – x̄ = 119 ± 7.175
• Average Biomass – 83,979.41 g deposited – ~71,698.5 g returned to water as hatchlings
Con&nua&on
• 2013 excava&on data
• Sea oats stabiliza&on and compac&on tests
• GIS nest density and distribu&on
References • Bouchard, Sarah H. and Bjorndal, Karen A. "Sea Turtles as
Biological Transporters of Nutrients and Energy from Marine to Terrestrial Ecosystems." Ecological Society of America. Vol. 81, No. 8 (2000): 2305-‐2313. JSTOR. Web. 18 May 2013.
• Hannan, Laura B. et. al. "Dune Vegeta&on Fer&liza&on by Nes&ng Sea Turtles." Ecological Society of America. Vol. 88, No. 4 (2007): 1053-‐1058. JSTOR. Web. 18 May 2013.
• Madden, Derek. et al. "Sea Turtle Nes&ng as a Process Influencing a Sandy Beach Ecosystem." Biotropica. Vol. 40, No. 6 (2008): 758-‐765. JSTOR. Web. 20 May 2013.