Sea Turtle – Page 2 – NOAA Teacher at Sea Blog

July 19, 2006March 19, 2021

Patricia Greene, July 19, 2006

NOAA Teacher at Sea
Patricia Greene
Onboard NOAA Ship Hi’ialakai
June 26 – July 30, 2006

Mission: Ecosystem Survey
Geographical Area: Central Pacific Ocean, Hawaii
Date: July 19, 2006

A large green sea turtle basking in the sand.

Science and Technology Log

Unlike the spinner dolphins, we have observed the Hawaiian green sea turtles tend to be rather shy and elusive. We managed to catch just glimpses of them from a distance. Based on past slaughters by man it is no wonder these creatures would avoid contact with humans. Historically, from the late 1800’s until 1970’s these creatures were slaughtered and harvested. Finally, in 1978 turtles were recognized under the U.S. Endangered Species Act however, they are still harvested in many parts of the world.

Several adaptations make the green sea turtle well suited for life in the ocean. Special lachrymal glands in the eye assist in the regulation of salt in the turtle’s body, preventing it from becoming dehydrated. When sea turtles shed tears they are actually removing salt from their bodies. Sea turtles are capable of storing large amounts of oxygen in their blood and muscle tissue, and lungs are adapted for rapid exchange of oxygen. Green sea turtles can stay under water up to five hours. Modified forelimbs give the sea turtle an efficient forward power-stroke. Protective coloration in the form of counter shading and blending gives the sea turtles camouflage. The underneath of the shell is cream color so the turtle blends with the sky and water to anything looking up and has a dark top shell for any predator looking down.Our luck changed on Southeast Island at Pearl and Hermes Atoll in the Hawaiian Islands National Wildlife Refuge. While circumnavigating the island we viewed a large adult green sea turtle pulled out and basking on the beach. After lunch we viewed from a distance two more green sea turtles basking and swimming in the surf. Researchers told us that they often observe 10 to 20 turtles pulling out at sunset and sleeping on the beach at night. It is more common in the Northwestern Hawaiian Islands than the main Hawaiian Islands for green sea turtles to exhibit this basking behavior. It is thought the behavior may be an adaptation to the cooler waters (i.e., a mechanism of thermoregulation, or a predation avoidance strategy due to the high populations of tiger sharks).

Three endangered Hawaiian green sea turtles bask on Southeast Island in the Hawaiian Islands National Wildlife Refuge.

Green Sea turtles reach sexual maturity at approximately 25 to 30 years and reach a weight in excess of 200 lbs. Green sea turtle’s breeding behaviors demonstrate great stamina. Pairs may remain coupled for 10 to 12 hours and both sexes have multiple partners throughout the mating season. Adult males can be distinguished from females by their longer tails and curved claws on their flippers. After the hatchling breaks out of the shell it must then reach the surface. Hatchlings demonstrate “protocooperation” meaning they work together as a group for several days in a joint effort to reach the surface. The hatchlings take turns digging and resting. Once they are near the surface the heat of the day will immobilize them and they will not continue their escape until the evening temperatures have cooled the sand. In this way they avoid heat stress and predators.Green sea turtles are oviparous (lay eggs externally) in a sand pit on the beach. Nesting starts in May and continues through August. Critical components of the nest site must include: lack of predators, a moist substrate, and suitable temperatures and be located beyond the high tide mark. Typically the green sea turtle will lay 75 to 150 eggs at night, in a clutch and lay multiple clutches during the breeding season. Incubation takes 50 to 70 days depending upon ambient temperatures. Sex of the hatchlings is not determined at the time of fertilization or conception (no sex chromosomes) but dependent upon the temperature of the sand and individual position of the egg in the nest. This is called “TSD” or Temperature-Dependent Sex Determination. The pivotal temperature for the green sea turtle is 28.26 degrees Celsius (82.9 degrees Farenheit). This is the temperature at which equal number of male and female hatchlings will be produced. If the temperature falls below this number more males will be produced; above more females will be hatched.

Now the hatchlings must find their way to ocean, avoiding the ghost crabs of the night. It is thought they employ a variety of visual clues, “wave compass” and perhaps a “magnetic compass” in their effort to reach the ocean. Scientists believe the wave compass allows the hatchlings to get orientated directly against the incoming waves. The magnetic compass refers to the magnetite found within their brains that may align them with earth’s magnetic fields. Once they arrive at sea, they will dog paddle to open water; hiding in algae, drift lines or other floating debris.

A curious Hawaiian green sea turtle approaches underwater at Puako in the main Hawaiian Islands.

During this pelagic stage they are carnivores and feed on plankton. They will remain at sea in this hatchling/early juvenile stage for years, sleeping with their flippers folded over their back to diminish their chance of becoming a morsel for some predator. This stage is a period of rapid growth; perhaps 8 to 10 cm the first year. The young turtles will re-appear in coastal waters where they will continue to grow, graze on algae and become life-long herbivores. The green sea turtle has specialized microorganisms in the hind gut that digest the cellulose in the plant material. It is possible that juveniles establish this flora by practicing “scatophagy” or the ingestion of adult turtle feces.

Another concern for the green sea turtle population has been the appearance of fibropapilloma tumors. Tumors on the eyes, throat, lungs, kidneys, liver and intestines have been documented. Scientists believe a Herpes-type virus may be responsible. The disease is quite common in the mainland Hawaiian Islands but relatively rare in the Northwestern Hawaiian Islands. These tumors may blind the turtle or choke them depending on the location of the tumor. Fortunately, we did not observe any tumors while we have been in the Northwestern Hawaiian Islands.Typically sea turtles thrive on sea grasses, seaweeds and algae. Depending upon where they live their diets may vary; for example green turtles of the Pacific Ocean are more dependent upon algae and seaweeds than the sea turtles of the Atlantic Ocean that thrive on the sea grasses such as turtle grass. The diet of the green sea turtles at Kure Atoll consist of an algae called Codium edule. In the main Hawaiian Islands invasive alien species of algae in the marine ecosystems have displaced the native species of algae that the turtles have traditionally fed on. This has caused widespread damage to the coral reef habitats.

The Northwestern Hawaiian Islands are extremely important to the green sea turtles. It is one of the last places where turtles are not affected by man’s desire for beach front property; no issues of coastal development, domesticated predators, recreational activities, artificial lights, high speed boat traffic, or general coastal degradation of the habitat. Over 90% of Hawaii’s green sea turtles return to nest at the French Frigate Shoals. Turtles come from the far north end of the Northwestern Hawaiian Islands chain (Kure, Pearl and Hermes, Midway Atolls) and from outreaches of the main Hawaiian Islands to lay their eggs at French Frigate Shoals.

Special thanks to the Hawaiian Islands National Wildlife Refuge, United State Fish and Wildlife Service, Department of Interior for access to Southeast Island and an opportunity to spend a day with the NOAA Fisheries biologists to learn more about the spinner dolphin research they conduct during their field season.

June 22, 2005March 18, 2021

Mike Lynch, June 22, 2005

NOAA Teacher at Sea
Mike Lynch
Onboard NOAA Ship Delaware II
June 20 – July 1, 2005

Mission: Clam and Quahog Survey
Geographical Area: New England
Date: June 22, 2005

Science and Technology Log

Latitude: 3726.163N
Longitude: 07444.980W
Wave Height: 1 foot
Swell Height: 1
Foot Weather: clear
Visibility: unlimited
Wind Speed: 7 mph

Scientific Log

Our first real shift for the DELAWARE II Ocean Clam Survey began this morning off the coast of Long Island. The shift stated at midnight, so we were awaked at 11: 15. Our first dredge occurred at 2:15 AM. We are working in a crew of six. Two of us input data into the FSCS computer as the deck crew coordinates with the boatswain in charge of the winch. Safety is a big issue on the NOAA vessel, and scientists are not allowed on deck while the dredge is being lowered off the stern. A high voltage cable is fed out along with the winch cable, and no one is allowed ion the deck until the dredge is in position for tow. Our job upstairs is to coordinate with the Officer of the Day when each step is being done and input his into the computer. Each actual tow takes five minutes, but the entire process of lowering the dredge, dredging and raising the dredge onto the deck takes about 25 minutes. When the dredge is brought up, our job begins.

We often start by places a smaller mesh screen at the front of the dredge in order tot capture the contents and releasing the dredge into a tow to wash away some of the debris and substrate soil. When the dredge is brought in the second time it is hauled up to an enormous table where the contents are released for inspection of our crew. It is then our task to sort through large amounts of shell hash, rock and substrate and find the living organisms. Our trawl today has been averaging at depths of 60 meters (180ft. or 30 fathoms in you want to be really cool and nautical). This is Ocean Quahog territory. True to form, our first three station trawls resulted in large numbers of Ocean quahogs as well as the assorted species. For commercial fisherman, these other species are often referred to as discard. These are unwanted species, or at least not the targeted stock. Today along with the quahogs, we caught several varieties of clams. These smaller clams were varieties such as Asterias, Astarte, Astrope, and Razor. We also collected Sea Scallops and Horse mussels. We Few fish are caught in bottom dredges, but we did catch one small Sea Robin and a small Skate. At first, I thought the unwanted species were called bycatch, but through interviews with on board fishermen and scientists I was informed that the term bycatch more commonly refers to sea mammals, reptiles or marine birds that are accidentally caught or killed in commercial fishing.

For example, in the area of scallop dredging, there has been a great deal of controversy surrounding the bycatch of endangered species of Sea Turtles. After each tow the catch was sorted, measured for length, and weight and catalogued into the computer database. What used to be done by pencil and paper is now done via electronic scans and scales. For quahogs under 40 mm, or above 110 mm in length, we conducted meat weigh measurements as well. This is hard work, and the ship conducts non-stop tows and data collection 24 hours a day. We are learning fast and having fun. The six-hour shift flew by and I was exhausted. A great morning, in bed by 7AM, and ready for the next shift at 11:30 AM. What a weird schedule. We have all been at it for a day and a half, and no one seems to know what day it is. As part of today’s log, I need to share what I have learned about the mysterious Ocean Quahog. The IO\Ocean Quahog, (Antica Islandica) is found from Newfoundland to Cape Hatteras. They are usually found in depths from 8 to 256 meters. They are a relatively cold-water species and are rarely found in waters above 16 degrees Celsius.

Their population densities are greater in off shore waters and they prefer a substrate of fine sand. In Maine they are found in shallower waters, but the populations are small, and the species grows at a slower rate. The average size is about 70mm. But today we had one at 110mm. What are really incredible about Ocean Quahogs are their ages. The scientists we interviewed today estimated that most of the many of bushels of quahogs we captured were in the 45 year old range. Quahogs can be in excess of 170 years old. Their most dramatic growth occurs in their first twenty years of life and the growth process slows significantly. Their ages are incredible, I may have to feel guilty the next time I spoon into clam chowder. Marine biologists have been finding that the Ocean Quahog, like the Atlantic Surf Clam, has shifting population strata. Surveys conducted over the past two decades and commercial fishing statistics show a pattern in which the Surf Clams are establishing themselves in deeper areas where quahogs previously predominated, and that the quahog populations are showing patterns of migration further offshore and further to the North.

One scientist onboard speculated that clam and quahog surveys might be important in the study of global warming. Ocean Quahogs have a commercial market value. The principal commercial fishing for the species occurs off the Delmarva Peninsula, New Jersey, Long Island and even Southern New England. In 1993, the commercial harvest of Quahogs reached its zenith at 25,000 metric tons. In 2000, the harvest had diminished to 14,000 metric tons. The decline in the fishery has been in part due to increased regulations under the Surf Clam- Ocean Quahog Fishery Management Plan (FPM), but also due to a decrease in the number of clamming boats and a depressed commercial market. Despite the reduction in total landings, the Quahog stock may be in jeopardy. The total landings are less than two percent of the total environmental stock, but any greater landings may threaten replacement levels and sustainability of this slow growing species.

Personal Log

Things were going along well until electrical problems with the dredge shut us down. Time to go to work on a different sort of problem.

April 18, 2005March 18, 2021

Melissa Fye, April 18, 2005

NOAA Teacher at Sea
Melissa Fye
Onboard NOAA Ship Hi’ialakai
April 4 – 25, 2005

Mission: Coral Reef Ecosystem Survey
Geographical Area: Northwest Hawaiian Islands
Date: April 18, 2005

Location: Latitude: 23*36.3’North, Longitude: 164*43.0’W

Weather Data from the Bridge
Visibility: 10
Wind Direction:90
Wind Speed: 14 knots
Sea Wave Height: 2-4 feet
Swell Wave Height: 5-7 feet
Sea Level Pressure: 1018.8
Cloud Cover: 2/8 Cu, As, Si
Temperature outside: 24.4

Science and Technology Log

The AHI research vessel was launched just prior to eight a.m. this morning with Scientist Joyce Miller and Jeremy Jones aboard. The red and silver sonar boat would continue mapping shallow areas near 23 degrees North and 166 degrees West in the Northern Hawaiian Island chain. The ship resumed running benthic habitat mapping lines also, filling in gaps from previous surveys. Half past noon brought the deployment of several divers to the hull of the ship to determine the installation of the Trackpoint II testing. They dove in adorned with black suits, colorful air tanks, and metal weight belts. It turned out that the Trackpoint II wasn’t installed properly and was off by 15 degrees. That noted, changes were made to computer software to account for the degree change. Another boat trip was organized for the La Perouse Pinnacle area. Coxswain Merlyn Gordon led me, ENS Amy Cox, Scientists Rob O’Connor and Jonathan Weiss out to sea to snorkel the reef ecosystem. Upon approaching La Perouse, it was determined to be too dangerous, so we changed course and swam the reef area near East Island. We returned to the ship a few hours later and the AHI followed suit, and was hoisted out of the water once again. The HI’IALAKAI transited to deeper waters and ship based TOAD operations and Trackpoint II testing carried on once again. Ten p.m. brought about the reoccurrence of shipboard mapping around the outer circumference of French Frigate Shoals using the onboard multibeam sonar system.

Personal Log

I awoke and after the morning ritual of breakfast and shower, I answered emails from students in my fourth grade classroom in Ashburn, VA. I climbed the stairs and passageway to the drylab to check to see if I could be of some assistance editing data. The efficient scientists were caught up on the editing so my services were not needed. I soon found out about an impromptu snorkeling trip and clambered to get ready and join the expedition. The seas were the calmest I had seen yet, so the ride was very smooth across the Pacific towards Perouse Pinnacle (a volcanic rock out cropping that serves as a good landmark in this area). The ocean looked like glass and the sun rays flashed and hit the water like bright diamonds. There was an underlying surge though, which might indicate a coming storm in the next 48 hours (according to sailors onboard).

After nearing Perouse, we could see the waves crashing around the rock, and pressed on for a safer snorkeling environment where we wouldn’t be churned to bits! We approached East Island and could see dark figures grazing the beach. Upon closer inspection, we realized they were not monk seals, but giant green sea turtles basking in the sun. Mating season was upon us, and many of the sea turtles were populating this area to find mates. We snorkeled in four different areas of the reef, being careful not to get near the beach or disturb the coral reef ecosystem. Several sea turtles were curious and encircled our boat, whereas I snapped some good photos.

I finally saw my first Ulua fish, indigenous to this area. The fish had eluded me prior to today and I had been told stories of their aggressive biting behavior. Although quite large, about 3-4 feet, I was told it was small compared to most. It swam around us, but never ATTACKED! It wasn’t nearly as ferocious as the picture the crew on board had painted in my mind. It was a very flat, circular fish with a silver sheen. We saw many school of fish, one of which was bright yellow, and neon green coral. I learned from Coxswain Gordon that some of the clouds above the reef bore a greenish undercast or tint. The color was reflected from the coral below and was an aide in locating reef areas. We returned to the HI’IALAKAI later in the afternoon and I spent the evening conducting some more interviews (which will be included in future logs). The sun and exercise tired me out and I fell asleep as soon as I hit the pillow in my stateroom.

QUESTION OF THE DAY for my fourth grade students: A habitat is the place where an organism lives and grows. Examples include ponds, forests, and a coral reef. A niche is the role an organism plays in its surroundings. A niche includes an animal’s complete way of life–where it lives, how and what it eats, and how it produces. Find out more about the giant green sea turtle. Think about why the turtle is laying on the beach also. List the answer’s to the sea turtle’s niche: 1) Where does it live? 2) How does it eat (what body parts does it have to aid in eating?) 3) What does it eat? (don’t say it eats Ms. Fye:)!! Ugh! 4) How does it reproduce? (Does it give birth to live young, lay eggs, etc?) 5) What resource did you use to find these answers?

ANSWER TO YESTERDAY’s Question: The ocean floor is full of nutrients and food particles resulting from decaying matter settling on the bottom.