Conservation and Ecology of Marine Reptiles MARE 490 Dr. Turner Summer 2011

1. Conservation and Ecology of Marine Reptiles MARE 490 Dr. Turner Summer 2011

2. Foraging Ecology & Nutrition Role of sea turtles in marine ecosystems Understanding of quantitative aspects of: diet selection digestive processing nutrition Coordinate population structure & food web analysis

3. Biomass Pyramids: Transfer of energy “Whoa, slow down there maestro. There's a New Mexico?” – C. Montgomery Burns Food chain efficiency (gross ecological efficiency) Energy to next trophic level Energy received from lower trophic level = ~2% of light E-> organic substance (autotrophs) ~80-95% lost at each transfer (trophic level)

4. Ecosystem Energy Flow 500,000 units of solar E ≈ 2% transfer 1 unit of human E converted to human mass ≈ 10% transfer 10,000 units 10 units 1,000 units 100 units

5. E! Where did the E go?Why is transfer efficiency so low? Loss due to incomplete transfer among trophic levels 1) Not eaten (evades or dies) 2) Inefficient conversion E= P + R + W E= ingested energy P = secondary production R = respiration W = waste

6. First name Mr, middle name period, last name E “Quit your Jibba Jabba fools!”– Mr. T E= P + R + W Assimilation efficiency (A)= (P + R) P = Secondary Production = growth, fat storage, birth R = Respiration = energy lost through respiration Assimilation efficiency:the percentage of what is initially consumed that becomes incorporated into the consumer

7. Gonna' teach this sucka a lesson! “As a kid, I got three meals a day. Oatmeal, miss-a-meal and no meal”– Mr. T Assimilation efficiency affected by: 1)Food quality 2)Amount of food 3)Age of consumer Therefore…assimilation is opposite of excretion (waste) E = A + W Energy available to the consumer is 1° a function of assimilation efficiency

8. Foraging Ecology Tremendous gaps in knowledge Foraging habitat typically separate from nesting & juvenile habitats How do we determine diet in protected species? Feces – pellets Stomach lavage Biochemical techniques Stable isotopes Fatty acids

9. Movie Green Feeding Ecology Juveniles in pelagic stage – thought to be omnivorous to carnivorous Associated with Sargassum mats? Known to feed on jellies

10. Green Sea Turtles Empirical evidence of difference in pelagic vs. neretic feeding ecology? RS1 – smaller RS3 – larger Seaborn et al. 2005

11. Green Sea Turtles Enter neretic habitat and shift to herbivorous diet 20-25 cm (Atl) 35 (Hawaii) Why herbivorous? Lower trophic level; higher energy Niche Low assimilation efficiency Either seagrasses (Caribbean) or seaweeds (Hawaii)

12. Movie Hawaiian Green Sea Turtles Feed on up to 56 species of algae; typically 9 Green, red, & Brown Feed on several introduced species Minimal feeding on seagrass (Halophila) & invertebrates (jellies & sponges)

13. Hawaiian Green Sea Turtles Low/no growth in several regions Poor food quality? Assimilation efficiency?

14. Movie Loggerhead Feeding Ecology Juveniles – associated with Sargassum Current fronts – mixture of drift material; algae, detritus, insects, crustaceans Rely upon jellies

15. Loggerhead Sea Turtles Adults – feed in benthos Primarily sea pens & crustaceans

16. Hawksbill Sea Turtles Juveniles – again with the Sargassum Carnivorous pelagic life history Recruit to neretic habitat 20-25cm; 35cm similar to greens