Scuba diving with loggerhead turtles in Isla Mujeres
The season is about to begin. Learn more about these incredible animals and the best ways to interact with them in the least invasive manner.
From May to July, in the crystal clear, turquoise waters of Isla Mujeres, the life cycle of the loggerhead turtles begins. Females return to their nesting grounds to find eager males awaiting them in the currents off the south end of the tiny Caribbean island called Isla Mujeres. This seasonal migration creates some unique diving experiences, and for non-divers, something magical can be witnessed (respectfully) on land as well.
Isla Mujeres Seasons
Isla Mujeres is blessed to be privy to some spectacular seasonal activities. From May to September, we see hundreds of whale sharks come to feed just off the coast; from November to February, the eagle rays return to hang out at our shipwrecks in huge numbers, and during the year, we get to watch the return of turtles, especially the gigantic loggerheads, to the island for the yearly mating and nesting.
Loggerhead Turtles (Caguamas)
At night, between May and October, the females come ashore on the Eastern, windward side of Isla Mujeres to lay their eggs in the sand of the same beaches that they hatched upon. By respectfully maintaining your distance, being with a registered guide from the Isla Mujeres Turtle Sanctuary, Tortugranja (soon to re-open, their efforts have been taken on by other volunteer organisations for now), and not using a flashlight, you can watch these massive turtles drag their huge bodies, designed for a life in the water, upon the sandy beaches to lay their eggs. These eggs are collected by volunteers so that they may be hatched in Tortugranja to give them the best opportunity for survival, free from predators and clumsy tourists.
Tortugranja organises turtle releases between July and October, and children line up to receive their buckets of baby turtles to be released into the ocean. These releases draw huge crowds of both local families and tourists.
Of the seven species of sea turtles, four live and make their nests off the Eastern coast of Mexico. These include Hawksbill turtles, Green turtles (Tortuga Blanca), Loggerhead turtles (Caguamas), and occasionally the grand leatherbacks.
May to July: mating
May to October: egg-laying
July to October: turtle release
Diving with the Loggerhead turtles
Everything we talk about in this blog leads to some of the most amazing dives that a diver with experience can do.
There are various types of diving that you can do where you have the chance to encounter these giants of the turtle world.
The drift dive is for the more advanced and adventurous, and you will be flying amongst dozens of these mating giants of the turtle world.
The night dive is a relaxing, peaceful dive with the perfect opportunity to see large numbers of resting sea turtles.
Both dives are spectacular and are bucket list dives.
Both dives are pure swim-by-dives, which means that a normal dive pace is maintained, and turtles are appreciated as the diver swims along without stopping, contacting or interfering with the turtles. To best appreciate the turtles, we must keep a distance and enjoy them purely by non-interaction. This way, they will return for many more generations to enjoy, and their natural life patterns will not be disturbed by ignorant and clumsy divers. The ocean is their playground, and we are privileged to view a small part of it.
For the non-diver - At South Point (Punta Sur) of Isla Mujeres, from the cliffs above on a calm day, you can see the sheer number of turtles that converge in strong water currents there. Under the water, it is a mating frenzy. At the season's peak, you are virtually guaranteed to see a staggering number of mating couples both from the cliffs and under the water.
The Drift Dive
The drift dive starts with, if the current is in your favour, passing by a huge Spanish anchor and chain. Then, the powerful currents carry you flying around the end of the island, taking you a long distance around. This current is perfect for our amorous couples, and you will find yourself distracted by one pair only to be carried onto the next and the next and the next.
Dolphins are commonly seen during this time and can be heard on nearly every dive. To see dolphins in their natural habitat is an experience way beyond seeing those in captivity. In fact, it is the ONLY way that they should be viewed. Also common on these dives are sighting some of the seven types of rays found here, batfish and schools of barracuda.
The strength of these currents means divers who attempt these dives should have experience beyond initial dive training, as extra vigilance is required to stay with your group and your buddy. Being distracted can mean being separated, and as such, only those who can respect the ocean and its ways should dive into these dives. Good buoyancy and the ability to follow an experienced guide and respect their briefings are necessary.
If you are unsure of your abilities, then it is recommended that you have a dive on the island before doing this dive to retune your buoyancy, refine your weighting and trim and evaluate your abilities. It will be worth it; it will be one of the most amazing dives you ever experienced.
The Night Dive
Night dives are another way to experience diving with turtles, as many come to rest under ledges and around the reefs of the Manchones National Park. The park is shallow (only 9mt) with very little current and fantastic visibility. Dozens, if not hundreds, of turtles can be seen on a night dive, but we must understand that these animals are at rest (mating and nesting can be hard work), so we should not disturb them nor shine our lights directly at them.
Even on the most normal, shallow dive for the less experienced diver, the chances of seeing some turtles are very high; we see them on nearly every dive during the season. It is awe-inspiring to see a loggerhead turtle swimming in the same waters as you.
About loggerhead turtles
Common name: Loggerhead turtle (Caguama in Mexico)
Scientific name: Caretta caretta
Family: Cheloniidae
Order: Turtle
Group name : Flotilla
Type: Reptile
Diet: Omnivorous
Sexual Maturity: 17-33 years
Life span: 47-67 years
Size in carapace : 78-95cm/28-37inches
Weight: 80-200 kg/180-440lb
Average weight: 135kg/298lb
Largest recorded: Length: 213cm/84in
Weight: 545kg/1202lb
Classification: Vulnerable - listed in 1978 as threatened under the Endangered Species Act
Loggerhead turtles are considered to be keystone species, meaning that they help define an entire ecosystem. Without them, the ecosystem would be dramatically different or cease to exist altogether.
The way they feed keeps the ocean floor sediment in balance by digging around the bottom. This changes its physical structure and the living biological ecosystem, helping the community organisation where they forage. The movement of the bottom sediment also results in a rise of oxygen in the water, and the overall productivity of the ecosystem benefits and improves because of this.
The Loggerheads feed on large numbers of invertebrates, recycling important nutrients from these hard-shelled prey. The shells of these prey pass through their digestive system, and what the turtles excrete falls to the ocean floor as a calcium source, fed by other animals.
The turtle shells act as an important habitat for many species of plants and animals. As many as 100 species have been recorded on a single turtle, including barnacles, crabs, and algae. It is unknown if this is a symbiotic relationship that allows the turtle to receive any benefit, although they may provide the turtle with some camouflage. One beautiful phrase I read describes this so eloquently by James R. Spotila. "Mobile islands transporting hitchhikers across the globe; they are like floating reefs."
Why are they here?
They are the most widely dispersed of all the sea turtles, existing in the Pacific, Indian, and Atlantic Oceans and the Mediterranean and Caribbean Seas. Dr Brian Bowen, a conservation geneticist, noted that there are, however, distinctive differences among the loggerheads around the world, and the use of modern molecular genetics has allowed historical relationships to be defined among populations and within a region. Dr. Bowen, his students, and colleagues used mitochondrial DNA to determine the unique distribution of loggerhead turtles. In other words, they can tell you what happened and how it occurred over millions of years of the Earth's evolution. Sea Turtles: A Complete Guide to Their Biology, Behaviour, and Conservation, written by James R Spotila (1), explains this in fascinating detail. He donated all proceeds from this book to The Leatherback Trust.
The greatest concentrations of Loggerheads live on the coasts of Mexico, Cuba, and Northern Bahama, up the coasts of the United States, and up to the Eastern coast of Canada. The greatest concentrations in the world exist in Florida, with about 67000 nests a year. Mexico has about 1200 nests a year. (1)
Mature females return to lay their eggs on the beaches where they themselves hatched. They do this by navigating Earth's invisible magnetic field. Each coastline has a magnetic signature that turtles can remember and use as a guide.
Just off the Southern point of Isla Mujeres, the female turtles are drawn to return to this area to mate in the strong currents, and the amorous males await them. This combination of seasonal return and the proximity of these currents to the island allows for an incredible diving experience for the more seasoned diver, unparalleled anywhere. It is not an unusual dive to be amongst 40-60 of these mating turtles at the peak of the season.
What do they eat?
The Loggerhead is omnivorous. Although primarily a carnivore, its diet consists of a variety greater than any other sea turtle.
They feed principally on bottom-dwelling invertebrates such as gastropods, bivalves, and decapods, but the list does not stop there. Their diet also includes sponges, corals, sea pens, polychaete worms, sea anemones, cephalopods, barnacles, brachiopods, isopods, Portuguese men o' war (brave turtles), insects, bryozoans, sea urchins, sand dollars, sea cucumbers, starfish, fish (eggs, juveniles, and adults), hatchling turtles (including members of its own species), algae, and vascular plants. During migration through the open sea, loggerheads eat jellyfish, floating molluscs, floating egg clusters, squid, and flying fish. (3)
Because their diet consists of jellyfish and benthic feeding, it is easy for plastic bags and plastic byproducts to be mistakenly ingested.
Since the 1940s, plastic has been mass-produced, and the impact of this has been devastating to sea turtles. Up to 52% of the turtles in the world have eaten plastic, and all of them are at risk.
According to a study from the University of Tokyo (6), loggerheads consume plastic in an alarming quantity, with 17% of loggerheads consuming plastic upon encountering it and 62% of Green turtles.
This consumption of plastic is devastating. It is a death sentence for 22% of all turtles that consume it. Sharp plastics rupture their internal organs, and plastic bags block the intestines, causing the turtle to starve to death. Even if they manage to survive this, the plastics can cause them to be unnaturally buoyant, which in turn causes their growth to be stunted and leads to slow reproduction rates (7)
Most of the plastic consumed was either transparent or translucent (similar to jellyfish), followed by the colour white. Black plastics ingested were mainly plastic bags, with green and blue being mainly plastic ropes and strings. Red, orange, yellow, and brown were the least (9). Why is this important? Because it may affect, at least, your consumer choices and habits; although we should all be plastic conscious, avoid all single-use plastics, and dispose of other plastics correctly or avoid them altogether.
How do they eat?
The Loggerheads have huge heads and powerful, massive jaws (hence their name) that are well-adapted to crush their hard-shelled prey.
On the anterior margin of their front limbs (forelimbs), they have projecting scale points that they use as "pseudo claws" that help to tear large chunks of food in their mouths. Food is filtered out in the fore region of their esophagus by inward-pointing, mucus-covered papillae that filter out fish hooks and foreign bodies. Further down, the esophagus lacks the papillae but has many mucosal folds.
The digestion of loggerheads, as with many other aspects of this species, is temperature-dependent. As the temperature increases, so does their digestion.
Mating
The male loggerheads arrive before the nesting season and wait in the mating grounds for the females to arrive. These are usually located offshore from the nesting beaches, and, fortunately, Isla Mujeres is very close to the Southern end of the island at South Point.
When the courtship and mating begin, the male will circle the female, then approach and bite her neck or shoulder. If she accepts him when he tries to mount her, they will mate. If she does not accept him, she will cover her cloaca and swim to the bottom. A persistent male will wait until she needs to surface for air and try again. (4)
The same claws on the forelimbs discussed above for feeding are also for holding onto the female during mating. The mating may last for hours, and other males often try to dislodge them by raming and biting the male. It is not uncommon during a dive here in Isla Mujeres to see one or even two other males pilling up on a male and female during mating. Another quickly replaces a dislodged male.
A female will lay several clutches during a nesting season and re-mate each time. Sometimes, she will mate with several males so that more than one male's sperm may fertilise a clutch. During this mating and nesting season, the males will remain in the water offshore of the nesting beach, and the females will alternate between mating, nesting, and feeding.
For each nesting, she must drag herself onto the beach, where she is in great danger of predators. She will spend one to two hours nesting, and she will bite if disturbed.
Nesting
Average of 3.9 clutches per season
Intervals of 12-17 days during nesting season
An average of 112 eggs
Eggs weigh 32.7g/1.2oz
Returns to nest every 2-4 years
It takes about 1-2 hours to complete the nesting process
Generally, at night in the open
A wider range of pivotal temperatures than other sea turtles determines the sex of loggerheads. A pivotal temperature is a temperature in which a ratio of 50:50 male: female is produced, generally between 28ºc and 30ºc.
Temperatures of 24ºc to 26ºc tend to produce males, and temperatures of 32ºc to 34ºc tend to produce females. Outside of the extremes of these ranges, eggs are just not viable.
It takes 45-80 days for an egg to hatch (depending upon temperature)
Hatchlings at the centre of a clutch are often the largest, more active in the swimming frenzy of the first few days at sea, and grow faster
At hatching, they weigh approx 20g (0.7oz) and are 5cm/2in length.
Hatchlings use visual cues to find the sea, responding to an arc 180º horizontally and 30º vertically. They appear to orient to the brightest light and the lowest elevation and can recognise some shapes.
Hatchlings will grow for 2-3 decades before returning to the nest
Female loggerheads will bite if disturbed while laying (with those jaws, something you do not wish to happen, so do not disturb!!)
Migration
Loggerheads are highly migratory and are found in all but the most frigid water on the planet.
When hatchlings leave the nest, they are 5 cm/2 in, and when they return, they are 50cm/20in (Atlantic loggerheads. Other regions are different sizes). For a long time, scientists did not know what happened to the turtles at this time, but thanks to biologists Alan Bolten and his wife Karen Bjorndal and the use of molecular genetics, radio and satellite remote sensing (biotelemetry), and computer technology, much was discovered. (2)
They found that after hatching, for the first few days, they feed on small animals and inanimate objects such as debris and oil droplets but then find their way to floating sargassum algae. These mats are home to many forms of life, both plants and animals. It is here that the turtles live at or near the surface, and they ride the currents as they leave the continental shelves and enter the open ocean.
They then spend 6-12 years at sea, spending the majority of their time, 75% of it, in fact, at the top 5mt/16ft. As they get older, they may dive to 200mt/650ft.
The Atlantic loggerheads return to the continental shelf (Neritic zone) when their shells are around 50cm/20in (this size varies depending upon the world region), where depths are less than 200mt/650ft. Here, they become bottom feeders (benthic) and capture feed in the water column.
To navigate, turtles use internal magnetic compasses, temperature variations in currents and convergence zones, and sun orientation. This is common in all reptiles.
Some loggerhead individuals have been known to migrate 4828km/3000 miles. Temperature plays a part in migration, as in every aspect of their life, and water temperature is a critical environmental cue as to when to move into and away from shallow water. When the water drops below 10ºc, it stuns the turtle, and they become lethargic and float on the surface. If it drops below 5ºc, they could die. Those that are in temperate waters avoid this by migrating toward the equator.
Interesting facts
The loggerhead turtle is on the $1000 Colombian peso coin, is the official state reptile of South Carolina, and also the state saltwater reptile of Florida
The sex determination of loggerheads is temperature-dependent. High sand temperatures produce higher ratios of females. Because of this, nesting sites that have unseasonably warm temperatures over a three-year period will produce an out-of-proportion number of females (87-99%). This connection between rapid global temperature changes and askew gender ratios raises concerns about the possibility of population extinction.
During mating, the female ovulates eggs that the males fertilise. This mating-induced ovulation is rare in non-mammals
Up to 40% of nesting females around the world have wounds believed to come from shark attacks.
Loggerheads are the best-known and most-studied sea turtles
They nest over the greatest geographical range of any of the sea turtles
They have salt glands (lachrymal glands) near the eyes that allow them to drink saltwater and excrete high salt concentrations. This gland enables the turtle to maintain osmotic balance, and it has often been misinterpreted as seeing a loggerhead female "cry" for her young when, in fact, she is just excreting salt
Loggerheads can hold their breath for extended periods. While most of their dives are about 4 - 5 minutes, they can dive for up to 20 minutes and rest without breathing for hours.
To navigate, turtles use internal magnetic compasses, temperature variations in currents and convergence zones, and sun orientation.
While most turtles can withdraw into their shells to escape predators, sea turtles cannot.
Threats
Bycatch
The greatest threat to all sea turtles is the worldwide, unintended entanglement and capture in fishing gear. This leads to the animal drowning, fatal injuries, or debilitation by swallowing lines and hooks. Trawls, longlines, gillnets, and hook and line are the greatest culprits, but pound nets, pots and traps, and dredge fisheries are also to blame.
Loss and Degradation of Nesting Habitat
Climate change is causing the sea to rise, and crucial nesting sites are lost. Coastal development is also to blame, taking much of what is left of nesting beaches for development. Hardening or armouring of the shoreline (as in seawalls) is taking away all dry sand used for nesting, and artificial light from development on or near the beaches may deter nesting females and disorientate new hatchlings.
One surprising developmental influence happened in Boca Raton, Florida, where the shadows on the beach from tall buildings cooled the sand, and mostly males were produced as a result.
Dimitris Margaritoulis is a pioneer in turtle conservation. Battling early developers that would destroy pristine nesting beaches, he paved the way for implementing national parks, nature conservation, and environmental education. Achelon, his Sea Turtle Protection Society, became a role model for other countries. He and his family possibly saved the loggerheads in Greece, as well as the Mediterranean. (1) and all because he took a family vacation, happened upon this miracle of nature, and was amazed and inspired to study, understand, educate others, and preserve them.
Boat Strikes
Near developed coastlines, there is an increasing number of injuries or deaths as a result of watercraft striking loggerheads that are at or near the surface. Areas such as marinas and inlets pose a greater risk, and near nesting grounds, where the animals that remain offshore to mate during the nesting season, especially the nesting females, are highly susceptible to vessels striking them.
Harvesting of Turtle Products
Loggerheads are less likely to be hunted for meat and shells than other turtles due to the meat tasting fishier than the Green turtle, and the shell, being covered in living things, is not as beautiful as the Hawksbill.
However, not long ago, all turtles were hunted for their products. It is not uncommon to see turtle eggs sold in bars in Costa Rica, and unfortunately, it is still a delicacy here in Mexico.
The Mexican government has placed turtles on the protected species list, implementing laws that mean killing turtles and stealing their eggs is punishable by jail time, but this is not the only threat to turtles.
Predation
Most turtles can withdraw into their shells to escape predators, while sea turtles cannot. Despite the loggerheads having a hard shell, being huge, and having their head and neck covered in rough, scaly skin, they are highly susceptible. When the females come upon the beaches to lay their eggs, they are vulnerable for the 1-2 hours this process takes.
Hatchlings and eggs have few defences and many predators, some destroying 80-95% of all nests. In many places, the human predation of nests is also substantial. Although hatchlings tend to emerge at night to lessen the chances of predatorial encounters, many are still taken by crabs, birds, carnivorous fish, and other predators.
Diseases
If there wasn't enough trouble for the loggerheads, there is a disease called fibropapillomatosis, or FP, which continues to spread globally. It is a type of herpes (different from the human type) that causes cauliflower-type tumours around the eyes, mouth, flippers, and internally. It is unknown what causes it, but it is thought to be attributed to warmer seas and water pollution.
It afflicts all seven types of sea turtles and causes great suffering to those infected. It is most commonly found in turtles living in polluted, dirty water caused by developed areas. As hatchlings and adults live in the open ocean, it is primarily juveniles that show symptoms as they live close to shore (12)
Pollution/Debris
As discussed previously, the impact of plastics on the turtle and marine populations has been devastating, to say the least. They mistake for food many human byproducts such as fishing hooks, lines, plastic bags, tar and oil, and much other plastic debris. They become entangled in marine debris, such as discarded fishing lines, which may result in injuries and death.
Join the Fight Against Plastic Pollution
Global warming
Nesting sites that have unseasonably warm temperatures over a three-year period will produce an out-of-proportion number of females (87-99%). This connection between rapid global temperature changes and askew gender ratios raises concerns about the possibility of population extinction.
What is being done?
In 1990, Mexico announced a total and permanent ban on the capture and trade of sea turtles and their products. This covered ALL sea turtle species on both the Pacific and Atlantic beaches. The Olive Ridley turtle slaughterhouse was closed in Oaxaca.
A group called "Grupo de Los Cien" and conservationists had disclosed the extent to which turtles had been slaughtered and the blatant illegal trade of turtle products. This caused a massive public outcry. International support caused a barrage of tens of thousands of letters to the president, making him acutely aware of the international attention and concern to prevent the extinction of these animals.
A presidential decree was put into motion that increased on-site protection, more support for research and training programs, and the development of alternate sources of income for those dependent on exploiting the species. (14)
Much is being done to ensure the survival of loggerheads everywhere. They are protected by national laws in the US, and NOAA`s National Marine Fisheries Service and US Fish & Wildlife Service monitor populations regularly.
Fishing gear modifications are reducing bycatch; there are closures of certain fishing areas around the world during mating, nesting, and hatching seasons.
Some communities are developing a light ordinance to reduce the disorientation of hatchlings.
In Greece, night flights were banned in certain areas.
Nesting beaches are being acquired for long-term protection.
Perhaps one of the biggest rays of sunshine is that Coca-Cola, long known to be one of the largest contributors to the plastic contamination of the planet, is changing to plant-based bottles by 2023 and sharing this technology with the rest of the world (15). There is hope for us yet.
Impact of Ecotourism on Loggerhead turtles
Sea turtles are an attraction for ecotourism, and it is popular for people wanting to dive and snorkel with them for those who wish to watch the nesting process (under guidance) and take part in the release of hatchlings. As the Loggerhead is the most common turtle, most widely dispersed and studied, it is a great alternative to the prior extortion of their products although, in Africa, Asia, and the Mediterranean, these turtles and their eggs are still exploited for food.
Tourists can volunteer at the turtle farm (Tortugranja) and, after a small introductory session, will be certified to help collect the eggs. Without this training, tourists are strongly advised not to individually set up to watch nesting females due to the lack of training and understanding. It is important to understand the needs of a nesting female and how to not unintentionally affect or disturb the process.
If we can balance eco-tourism with the impact of tourist development, we can hopefully find a way to coexist that benefits all.
What You Can Do To Protect Nesting Loggerhead Sea Turtles
-Remove beach litter
Balloons, plastic bags, foam, fishing gear, and other non-degradable litter can cause the deaths of many sea turtles who mistake them for food.
-Observe from a distance
If you encounter a nesting turtle, do not shine any lights on or around her - she may abandon her effort to nest.
Do not use flash photography. Stay behind the turtle so that she cannot see you.
-Do not harass a turtle
Don't touch or prod her to move. Stay out of the way as she crawls back to the water.
-Leave nest sites alone
If you see a nest, don't disturb it. Leave any identification markers in place. If you find a hatchling wandering in daylight, place it on moist sand in a dry container, shade it, and call one of the numbers listed below.
-Report injured turtles
Call to report dead or injured turtles.
-Lights Out! (see above)
If you treat the turtles with respect, you can have a fun, enjoyable encounter.
In Conclusion
When my Australian mother first saw loggerhead turtles laying their eggs on the beaches here in Mexico, she was so overwhelmed by what she saw that she cried. To be part of something so unique, such a circle of life happening in front of her, was an incredible experience that she still recounts to this day. We need to make sure that we do everything we can to protect the survival of this species so that all generations, present and future, can enjoy and coexist together.
It is thanks to the greats of turtle conservation and studies such as James R Spotila, Dr Brian Bowen, Dimitris Margaritoulis, and The Grupo de Los Cien, to name a few, that we are making progress in ensuring their survival, but the problem is so much greater. We, as a species, need to clean up our act, clean up our world and make conscious, educated decisions about how we interact with the world around us.
(1) Sea Turtles: A Complete Guide to Their Biology, Behavior, and Conservation. (2004). James R Spotila.
(2) Bolten, A. B., & Witherington, B. E. (2003). Loggerhead Sea Turtles (1st ed.). Smithsonian Books.
(3) Wikipedia contributors. (2021, February 26). Loggerhead sea turtle. Wikipedia. https://en.wikipedia.org/wiki/Loggerhead_sea_turtle
(4) Caretta caretta (Loggerhead). (2007). Animal Diversity Web. https://animaldiversity.org/accounts/Caretta_caretta/
(5) Loggerhead Turtle | Sea Turtles | Species | WWF. (2010). World Wildlife Fund. https://www.worldwildlife.org/species/loggerhead-turtle
(6) Sea turtles feeding habits influence reaction to marine debris. (2016). The University of Tokyo. https://www.u-tokyo.ac.jp/focus/en/articles/a_00487.html
(7) Nelms, S. E., Duncan, E. M., Broderick, A. C., Galloway, T. S., Godfrey, M. H., Hamann, M., Lindeque, P. K., & Godley, B. J. (2015, October 9). Plastic and marine turtles: a review and call for research. OUP Academic. https://academic.oup.com/icesjms/article/73/2/165/2614204
(8) Rotich, V. (2017, August 1). What are Benthic Animals? WorldAtlas. https://www.worldatlas.com/articles/what-are-benthic-animals.html#:%7E:text=Benthic%20animals%20have%20different%20food%20and%20feeding%20habits.&text=Other%20benthos%20are%20detritus%20feeders,who%20feed%20on%20other%20animals.
(9) To Eat or Not to Eat? Debris Selectivity by Marine Turtles. (2012). PubMed Central (PMC). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3400646/
(10) Endangered Species. (2018). National Wildlife Federation. https://www.nwf.org/Educational-Resources/Wildlife-Guide/Understanding-Conservation/Endangered-Species
(11) Merry, M. (2010, April 12). More Changes Needed to Protect Loggerheads. Endangered Species Coalition. https://www.endangered.org/more-changes-needed-to-protect-loggerheads/
(12) The race to save sea turtles from deadly herpes tumors. (2017, December 7). Oceana. https://oceana.org/blog/race-save-sea-turtles-deadly-herpes-tumors
(13) Witt, M. J. (2010, March 15). Predicting the impacts of climate change on a globally distributed species: the case of the loggerhead turtle. Journal of Experimental Biology. https://jeb.biologists.org/content/213/6/901
(14) MTN 50:1–3 Mexico Proclaims Total Ban on Harvest of Turtles and Eggs. (1990). Marine Turtle Newsletter. http://www.seaturtle.org/mtn/archives/mtn50/mtn50p1.shtml#:%7E:text=On%2028%20May%201990%2C%20the,Pacific%20or%20Atlantic%20coast%20beaches.
(15) Why we’re sharing our PlantBottle technology with the world. (2021, March 22). Coca-Cola Europe. https://www.coca-cola.eu/news/supporting-environment/why-were-sharing-our-plantbottle-technology-with-the-world?fbclid=IwAR36PPNX1E55X-MaMw1RfYv13Gv-ImHaKWUUUVgjnqHTRc94fVdpM4RUI3I