4/11/2019 Day Three

Departure was at 0745 hours from the HPA upper campus.  We arrived at our destination at 0830 and set up our work area for doing measurements and drawing blood.
We worked until 1400 hours and then packed up and headed back to the lab where we had another 2 hours during which we processed the blood and tissue samples.  We were able to capture 14 animals during the day and obtained blood samples from all of them.

RESULTS:

4-11-19 92 KIHOLO

14 total captures

8 new captures

6 recaptures

Below are images of the day at Kiholo and back in the laboratory.

4/10/2019 Day Two

Departure was at 0745 hours from the HPA upper campus.  We arrived at our destination at 0830 and set up our work area for doing measurements and drawing blood.
We worked until 1400 hours and then packed up and headed back to the lab where we had another 2 hours during which we processed the blood and tissue samples.  The green turtles at Puako are generally larger than those we encounter at Kiholo and they average about 55 cm straight carapace length.

4-10-19 92 Puako Beach Road, Puako

16 total captures

7 new captures

9 recaptures

Blood samples were drawn from 15 green turtles.

Below are images of the day at Puako and back in the laboratory.

Dr. Jones Oversees a student drawing a blood sample.

Laura Jim measures the curved carapace width of a captured honu.

The HPA team enjoys a glass of lemonade provided by Laura Jim.

Lunch time!

Dr. Allen demonstrates the technique used to draw a blood sample.

The HPA/NOAA team at the end of a successful tagging day.

4/9/2019 Day one

Departure was at 0745 hours from the HPA upper campus.  We arrived at our destination at 0830 and set up our work area for doing measurments and drawing blood.
We worked until 1400 hours and then packed up and headed back to the lab where we had another 2 hours during which we processed the blood and tissue samples.

For the day:

4-9-19 KIHOLO

17  total captures

11 new captures

6 recaptures

We also collected blood samples from all 17 turtles.

Below are some images of the work day and the work in the laboratory.

A panoramic view of our work area and the site.

Katie performs an oral exasm on a juvenile green turtle.

Katie and Annika help control a juvenile green turtle during measuring and weighing.  We put a number on each turtle so that people are able to report seeing individual turtles.

Hikari holds a turtle while Jimmy gets ready to collect a blood sample.

Katie holds a turtle while Hikari takes a blood sample.

Jimmy holds a turtle while  Dr. Jones draws a blood samploe.

Annika holds a vile with a tissue sample.

Back in the lab, Hikari decants serum from a centrifuged blood sample.

Annika pipettes serum out of centrifuged blood sample.

HPA's Role

The Sea Turtle Research Program at HPA has been in existence since 1987 (www.hpa.edu/turtle) During that time we have worked cooperatively with the National Oceanic and Atmospheric A/dministrations National Marine Fisheries Service (NMFS),  We have, when appropriate and possible, supported research objectives of the NMFS by providing logistical, material and scientific support.
The Hawaiian green turtle sex ratio project requires the collection of hundreds of blood samples from resident foraging green turtles and this is where HPA can help.  On April 8, 2019, a team of five
NOAA scientists traveled to HPA to conduct 4 days of education and tagging with Co-Directors of the HPA Sea Turtle Research Program Marc Rice and Laura Jim and students from the upper and middle school.

The 5 NOAA scientists gave 2 hours of presentations about their work in their particular areas of focus.  The last talk was presented by Dr. Camryn Allen, the PI of the sex ratio project.  She covered the ideas behind her sex ratio project and discussed the methodology that is being used to determine sex in each turtle using blood serum samples.  She also covered the rough outlines of what our field work would consist of and what the subsequent processing of the blood samples required.

All of the students that were to be involved in the capture work over the next three days were in attendance and learned a great deal about the various project ongoing at NOAA's Honolulu Lab.
The plan for the trips was to capture between 10 and 20 green turtles each day and draw a blood sample from each of them.  After each days capture work, the students and Camryn came back to the lab and centrifuged the blood, separated the serun from the cells and then put the serum samples in the liquid nitrogen freezer to transport back to Honolulu on Friday.

The Sea Turtle Sex Ratio Project

BACKGROUND

Unlike mammals, a sea turtles sex (male/female) is determined by the temperature at which they incubate.  There is a "pivotal temperature" (~29 degrees C) above which the developing embryos will tend to become females and below which they will tend to become males (figure below).

Since turtles lay their eggs in sandy pits on the beaches, the incubation temperature depends on exposure to sunlight, depth of nest and general overall climate.  In some areas the incubation temperatures are such that the ratio of males to females is about 50/50 and on other warmer beaches, more females are produced or on cooler beaches a higher ratio of males are produced.

CLIMATE CHANGE

As our climate changes as a result of "global warming", the incubation temperatures of sea turtle nests is increasing which leads to a higher ratio of female than males hatching on our nesting beaches.  In turn, this unbalanced ratio could lead to "feminization" of the population and decrease the chances of females being able to find a mate.  With fewer males, there would also be less genetic variation.

While this is a possible outcome of global warming, we want to be able to see if this is the case and the only way to do that is to count the numbers of females and males being produced.  Since nesting beaches are scattered around the world and / or are difficult to get to, it is not practical to try and determine the sex ratio of hatchlings.  In addition, it is not easy to determine the sex of a turtle until it is mature and develops secondary sexual characteristic (long tail in the males, for example)

In Hawaii, 94% of green turtles nest at French Frigate Shoals (FFS) in the Northwestern Hawaiian Islands.  This is a highly protected and remote atoll about 500 miles noRth of Honolulu, Hawaii.  Determining the sex ratio of turtles being produced on the nesting beaches of FFS would be very difficult and, as an alternative way to determine the sex ratio of turtles being produced at FFS, we can look at the young juveniles that recruit to the main hawaiian islands at 3-5 years of age b0%ecause we know that most of the (over 90%) were hatched at FFS.

There are several ways to determine the sex of a sea turtle: 1.  look inside at the gonads to see if there are ovaries or Testes, 2.  take a blood sample and analyze it for hormone levels (testosterone vs estrogen) and 3. wait until they reach maturity.  The first alternative is too invasive for the animal and the last takes too long (25+ years).  Consequently, we will use the second method and analyze blood samples for male and female hormone levels.  Using this technique, we will be able to determine the sex of a broad range of size classes of sea turtles and begin to develop a picture of the sex ratio in past years.  For example, a 55 cm sea turtle may be on the order of 15 years old and, hence, is a member of the turtles that hatched that long ago,,, perhaps in 2004.  This will allow us to determine the sex ratio that was produced over the last 20-25 years to present (the youngest/smallest turtles).

The Project

The project to determine the sex ratios of the green turtle population in Hawaii begins with the gathering of blood samples from juvenile and subadult green turtles in various habitats on all of the islands (in order to get a true picture).  These samples will be analyzed to determine the level of testosterone and label each turtle as a male or female.  Over time, with the accumulation of many samples from many islands, we will be able to determine the sex ratio of the Hawaii green turtle population over the last 20+ years and develop a picture of the potential impact of climate change on the sex ratio.  This is a long term/ongoing project that will continue for many years.