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Understanding Marine Reptile Foraging Ecology & Nutrition in Marine Ecosystems

This course delves into the intricate relationship between sea turtles and marine ecosystems. Topics include diet selection, digestive processes, population structure, and energy transfer through food webs. Explore why transfer efficiency is low and factors influencing assimilation efficiency. Discover foraging habits through various techniques like stable isotopes and fecal examinations. Contrasts in feeding ecology are noted between green, loggerhead, and hawksbill sea turtles in different habitats, shedding light on their dietary preferences and relevant ecological niches. Join us in unraveling the mysteries of marine reptile conservation and ecology.

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Understanding Marine Reptile Foraging Ecology & Nutrition in Marine Ecosystems

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  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

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