MWeinhouse: Hello Caroline, I just got your email about our shipment. I wante…

MWeinhouse's picture
MWeinhouse

Hello Caroline, I just got your email about our shipment. I wanted to ask, since you mentioned your marine science education. Are there any websites that shows a map of turtles sightings, studies around the island of Lana`i? My students want to know where they are, how many, which beaches they prefer to lay eggs. They would like to use this information to understand why we see turtles at certain beaches and some ways we may be able to help them prosper. Thanks for all your help! --Kapua

Mar 14 2018 - 4:57pm
caroline.greenwood's picture
caroline.greenwood

Hello Kapua,


Thanks for writing in! It’s great to hear that your students are pursuing a place-based project like this.


The tricky thing about studying sea turtles is that they are so highly migratory! Although we are lucky to have populations that remain local, they can travel thousands of miles, so it’s often very exciting to see the same individuals crop up. If your students are mainly interested in their locality, here are a couple great citizen science-based resources to get you started:


Hawaiian Hawksbill Conservation: http://www.hihawksbills.org/lanai-hawksbills.html

Lāna’i Marine Wildlife Project: https://www.inaturalist.org/projects/lanai-marine-wildlife-project


Although Polihua Beach on the north shore of Lāna’i was historically a popular nesting site, turtle catching and coastal development has threatened populations over the past few generations. Harassment issues like these are likely why tracking maps are so difficult to find. The critically endangered hawksbill turtles (Eretmochelys imbricata) are still known to nest within the main Hawaiian Islands, but green sea turtles (Chelonia mydas) now seem to prefer the undisturbed beaches of the Northwestern Hawaiian Islands.


Here’s a link to a report with anecdotal evidence of sea turtle population decline on Lāna’i — great for student discussion:
https://repository.library.noaa.gov/view/noaa/4245


Many of us are familiar with the natal homing behavior widely observed in sea turtles, and upon closer study, scientists have discovered similarities in popular rookeries (breeding sites). Green sea turtle eggs tend to fare best in fine-grained, moist substrate; however, additional factors can be equally as important to hatchling success. For instance, hatchlings exhibit phototactic behavior in that they move toward light stimulus. In undeveloped areas, the brightest light source would typically be the moonlight's reflection off the water, but artificial lighting adjacent to the beach can disorient hatchlings in their journey to the ocean. Consideration of natal homing through the lens of natural selection can make for interesting opportunity for exploration: if individuals return to their natal beaches, how does this indicate beach “quality”? And how can “profiling” these beaches help us focus conservation efforts?


This is a great study that further discusses the roles of these environmental characteristics: http://www.seaturtle.org/pdf/mortimerja_1990_copeia.pdf


Although there aren’t many population maps available to the public, it would be really interesting to see your students draw from their own knowledge of where they have seen turtles and consider environmental factors such as:

Beach structure - slope, substrate particle size / moisture content, etc

Food availability - abundance of frondose macroalgae such as Amansia glomerata (limu līpepeiao) and Sargassum polyphyllum (limu kala)


There’s definitely lots of research still necessary to understand sea turtle ecology within the Hawaiian Islands, but perhaps your students will be the scientists to fill those gaps in the future!


I hope these notes get you off to a good start! Good luck!


Caroline

Mar 19 2018 - 5:10pm