News
What’s killing off blue whales? Scientists say their ear wax can tell us
The endangered blue whale species could be saved by its ear wax, according to new research.
Throughout their lives, blue whales accumulate layers of wax in the ear canal that form a plug, almost a foot long, and which remain permanently in place until they die.
Scientists from Texas have analysed these layers, in a manner similar to tree rings, to roughly estimate a specific whale’s age, track changes in its hormone levels, and see which chemicals it was exposed to in the ocean.
This wax can also be used by researchers to work out what needs to be done to protect them from stress, pollution and other threats in the future.
The blue whale is the largest animal on Earth and is listed as ‘endangered’ on the International Union for Conservation of Nature Red List of Threatened Species.
Dr Sascha Usenko from Baylor University made the breakthrough by using the wax from a dead 12-year-old blue whale.
He found fluctuating levels of testosterone and the stress hormone, cortisol, during its life. At the time of its death, Usenko said the whale had twice as much cortisol in its blood than at any other point.
He believes this could relate to food availability, changes in social status, pollution exposure and environmental noise. Testosterone levels suggest the male blue whale reached sexual maturity at about 10 years of age.
‘The general increase in cortisol over the animal’s lifetime could be associated with a multitude of factors including weaning, development, sexual maturity, migration, food availability, environmental conditions, changes in social status, accumulated contaminant exposure or environmental noise,’ said Dr Usenko.
The study also showed the whale had accumulated substantial levels of pollutants – such as pesticides and flame retardants – within its first year of life during gestation or nursing.
In contrast mercury levels in the earplug – which measured around 10 inches – spiked during two distinct time periods later in the animal’s life.
The researchers suggest earplug analysis could help assessments of the impacts of human activities on marine organisms and their ecosystems.
‘Currently obtaining lifetime chemical profiles from birth to death is extremely rare and difficult for most of Earth’s animals,’ said Dr Usenko.
‘We have developed a unique approach to quantify hormone and contaminant lifetime profiles for an individual blue whale using the wax earplug as a natural matrix capable of archiving and preserving these temporal profiles.
‘Using a male blue whale earplug chemical analysis reveals lifetime patterns of mercury and organic pollutant exposure as well as fluctuating hormone levels.
‘We anticipate this technique will fundamentally transform our ability to assess human impact on these environmental sentinels and their ecosystems.
‘The use of a whale earplug to reconstruct lifetime chemical profiles will allow for a more comprehensive examination of stress, development, and contaminant exposure, as well as improve the assessment of contaminant use or emission, environmental noise, ship traffic and climate change on these important marine sentinels.’
Dr Usenko added the 70ft blue whale he studied was hit by a ship off the coast of California in 2007.
Blue whales are the largest mammal to have ever existed on Earth and grow up to 90ft and can weigh 150 tonnes.
They could once be spotted in all major oceans and numbers topped around 200,000, yet after being hunted almost to extinction, there is now thought be as few as 8,000.
The International Whaling Commission has taken steps to protect these creatures by appointing committees of experts to work against whaling, entrapment and predation, but their population remains low.
The findings were reported in the Proceedings of the National Academy of Sciences journal.
Source: Daily Mail
The Kingdom of the Netherlands will ask for increased protection for the Caribbean reef shark during next month’s Conference of Parties for the Cartagena Convention (COPs) on Aruba. Caribbean reef sharks play a critical role in maintaining a healthy reef ecosystem and building resilience within the oceans. This increased protection is critical for ensuring a sustainable future for this iconic species.
The Caribbean Sea is renowned for its crystal-clear waters, vibrant coral reefs, and a dazzling array of marine life. Among the charismatic inhabitants of this underwater paradise is the Caribbean Reef Shark (Carcharhinus perezii), a species that plays a crucial role in maintaining the health of coral reef ecosystems. In the Dutch Caribbean, these apex predators face mounting threats, but there is hope on the horizon. At the upcoming Conference of Parties for the Cartagena Convention (COPs), the Kingdom of the Netherlands will seek increased protection for these magnificent creatures by listing this species on Annex III of the SPAW Protocol. Annex III includes plant and animal species which require additional protection to ensure this species is able to adequately recover their populations in the Wider Caribbean Region.
Importance
Caribbean reef sharks thrive in warm, tropical waters of the Caribbean region, with a distribution range that stretches from Florida to Brazil. This species is one of the most encountered reef shark species throughout the whole Caribbean Sea. Growing up to 3m (9.8ft) in length, this shark is one of the largest apex predators in the reef ecosystem and is at the top of the marine food web, having only a few natural predators.
In addition to being of great economic value, as shark diving is a major draw for divers from around the world, this species is also critical for maintaining balance within the reef ecosystem. Their presence helps regulate the population of smaller prey species, which in turn, prevents overgrazing on seagrass beds and coral reefs and eliminates sick or weak fish from the population. This balance is essential for maintaining the health and diversity of the entire coral reef.
Threats
Despite their ecological and economic significance, Caribbean reef sharks in the Caribbean face numerous threats that have led to a population reduction estimated to be between 50–79% over the past 29 years. In the (Dutch) Caribbean this is mainly caused by:
Habitat Degradation: The degradation of coral reefs and seagrass beds due to climate change, pollution, and coastal development has a direct impact on the availability of prey for these sharks. Loss of habitat reduces their ability to find food and shelter.
Overfishing: Overfishing poses one of the most immediate threats to Caribbean reef sharks. They are often caught incidentally in commercial fisheries, where fishermen are targeting other species, or intentionally, where they are sought after for their fins, used in shark fin soup.
A Call for Increased Protection
There are different organizations and individuals working to protect sharks and their habitats in the Dutch Caribbean. A significant milestone was the establishment of protected areas such as the Yarari Marine Mammal and Shark Sanctuary between Bonaire, Saba and St. Eustatius. Another milestone was in 2019 when the Dutch government adopted an International Shark Strategy. The strategy sets out which protective and management actions for sharks and rays are to be taken by the government in all seas and oceans where the Netherlands has influence (including the Dutch Caribbean). Additional efforts are still needed to create more marine protected areas, enhance enforcement, reduce pollution in the ocean, and promote sustainable fishing practices. These species know no (political) boundaries and their protection requires broadscale conservation efforts within the Dutch Caribbean and beyond.
Conclusion
The Caribbean reef shark is a species of paramount importance to the (Dutch) Caribbean’s coral reefs. With the extra protection being requested during the next COPS meeting in Aruba, there is hope that this species will have a healthy future. By recognizing their ecological significance and the challenges they face, we can work together to ensure a brighter future for the Caribbean Reef Shark in the Dutch Caribbean and beyond.
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DCNA
The Dutch Caribbean Nature Alliance (DCNA) supports science communication and outreach in the Dutch Caribbean region by making nature-related scientific information more widely available through amongst others the Dutch Caribbean Biodiversity Database, DCNA’s news platform BioNews and the press. This article contains the results from several scientific studies but the studies themselves are not DCNA studies. No rights can be derived from the content. DCNA is not liable for the content and the in(direct) impacts resulting from publishing this article.
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Photo + photo credit: Jim Abernethy-all rights reserved
For more information, please contact: research@DCNAnature.org
News
Dive Pirates Foundation nominated for DEMA’s Community Champion Award, asking for DEMA Members to vote now!
Dive Pirates Foundation is proud to announce it has been nominated for DEMA’s 2023 Diving Community Champions award. The Foundation is asking all DEMA members to support the crew and vote to recognize the great efforts achieved in 2023!
Specifically, DPF is being recognized for this year’s “Find Your Inner Treasure” effort, which brought the world of scuba diving to 6 adults living with disabilities. Through this effort, the recipients – 5 of whom are military veterans – were equipped fully and trained by their local dive shops before enjoying a week-long dive trip to Cayman Brac Beach Resort. While at the resort, DPF provided additional volunteer instructors and adaptive buddies for all participants to dive adaptively alongside industry professionals and returning adaptive divers alike. For many of the new divers, these dives were their first open water diving experiences. By the end of the week, all new divers had completed more than a dozen open water dives, with some also earning their open water diver certification.
However, Dive Pirates’ “Find Your Inner Treasure” effort also provides something much more than a scuba diving trip: freedom. The new divers frequently used this word to describe the feeling of scuba diving, with many expressing that they thought diving was unattainable for them with their disability. For them, this trip was much more than a vacation. It was a confidence boost and validation of their ability.
New participants also found themselves welcomed into the Dive Pirates family and the dive community at large. Throughout the trip, DPF provided its participants new and old with fun events at the resort in order to build camaraderie and to promote a welcoming, inclusive environment for the 6 new divers. With the new members eager to return for future dives, as well as 8 past recipients, one stowaway adaptive diver, and other divers making this their vacation volunteer effort resulting in 64 travelers, 2023 marked another successful year for the Dive Pirates Foundation.
Now, DPF needs you to vote so they can be recognized for their amazing work! Voting closes October 12, 2023, at 4:00 pm US Pacific Time. DEMA members can vote for DPF here.
The Dive Pirates Foundation a 501(c)3 organization, positively impacts the lives of its recipients; injured military, first responders, law enforcement and others with mobile disabilities, by welcoming them into adaptive scuba diving which fosters accomplishment, self-worth and community. The Foundation trains, equips and conducts dive trips year-round to calm, warm-water locations for the safety of those with spinal cord injuries, networking with facilities willing to empower all participants with compassion and adaptation for a positive experience diving, team building and networking.
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