FACT OF THE WEEK: Whales play a crucial role in the carbon cycle

MORE ON THIS: In a previous Fact of the Week, we learned how plankton helps the oceans ‘biological pump’, a process that supports the global carbon cycle by removing carbon from the air and storing it in the deep sea. This week, we’re going to talk about the largest living creatures in the ocean, whales, and their role in the carbon cycle. Their movements, deaths, and even feces all contribute to the ‘whale pump’ which works with the biological pump to promote carbon storage.

Movement: When whales swim from deep waters to the surface, they move nutrients up with them. Bringing nutrients to the surface increases the food source for phytoplankton, which play the first part in carbon uptake.

 

Death: When dead whales sink to the ocean floor, they take with them all the carbon that has built up in their body over their lifetime. As the largest marine mammals, that’s a lot of carbon, similar to the huge amounts of carbon stored in old trees.

Feces: When whales swim to the surface, they poo, releasing large fecal plumes which are extremely nutrient-rich and widely consumed by plankton. As one of the larger whale species, sperm whale poop alone might remove hundreds of thousands of tons of carbon from the atmosphere by promoting plankton growth.

Before population declines due to industrial whaling, it is estimated that large baleen whales used to remove millions of tons more carbon than they do today. Scientists suggest that restoring whale populations could greatly increase ocean carbon storage again and may be just as effective as reforestation projects and ocean iron fertilization.

By Kaitlin Yehle

 

FURTHER READING:

  1. Whales Keep Carbon out of the Atmosphere.
  2. The Impact of Whaling on the Ocean Carbon Cycle: Why Bigger Was Better.
  3. Whales as marine ecosystem engineers. Frontiers in Ecology and the Environment. Roman J, Estes JA, Morissette L, Smith C, Costa D, McCarthy J, Nation JB, Nicol S, Pershing A and Smetacek V. 2014. 12(7): 377-385.

 

FACT OF THE WEEK – Plankton, the unsung hero of the ocean

Zooplankton caught in the leeward waters of Maui. Specimens shown under the microscope.

 

 

 

 

 

 

 

 

 

Here in Maui we witness one of the greatest migrations in the world—that of the humpback whale. However, what our human eyes can’t see is another one of the world’s largest mass migrations happening every dawn and dusk in waters around the world.  Microscopic zooplankton move vertically through the water column to seek prey and avoid predators. This is called diel vertical migration (DVM).

Under the cover of darkness each night, zooplankton migrate to the surface of the ocean to feed on phytoplankton (“plant” plankton). In the darkness, predators can’t see them as well which makes feeding safer. Once the sun rises, the zooplankton retreat deeper into sea to avoid being seen by hungry fish. Because zooplankton are so small, this journey is as difficult for them as it would be for a person to swim through an ocean of molasses.

Here in Hawaii and throughout the tropics, plankton is much less abundant. This is why our water is so crystal clear and why whales must migrate up to Alaska’s plankton-rich water to feed. However, there are still small amounts of plankton in these waters, and the cycles of DVM affect it each day and night.

DVM is very important to a healthy ocean. After zooplankton fill up on carbon-rich phytoplankton and migrate deeper into the water column, they excrete that same carbon. This helps a process called the “biological pump” that captures carbon dioxide from the air and moves it into the deep sea where some provides nutrients for other organisms, and some becomes part of the sandy bottom.  If the biological pump didn’t exist, almost twice as much carbon dioxide would be in our atmosphere. DVM is a small variable in this large process that keeps our planet healthy.

 

For further information, see the links below.

By Simona Clausnitzer

Are the whales jumping for joy in Hervey Bay?

Breaching, or jumping out of the water, is a behavior that the PWF researchers in Hervey Bay and in Maui observe frequently. A commonly asked question is “Why do whales breach”? The short answer is that no one knows a single cause for this behavior; however, there are a number of theories about what drives such impressive whale acrobatics.

One possibility is that the whales breach just for fun, similar to humans and other terrestrial mammals when they are excited or playing. Another option is that they use breaching and other surface activity as a way of communicating to other whales. If you’ve ever been close to a breaching whale, you know that the sound is astonishing. The sound is also quite loud underwater and may be used to communicate the whale’s location or activity level to other whales in the distance. It has also been suggested that whales breach to deter predators or other perceived threats.

Young calves may have a completely separate motivation for breaching. As more mother and calf pairs enter Hervey Bay, researchers and whalewatch passengers alike can’t help but to notice the awkward jumps of young calves. These calves are trying to imitate what the larger whales are doing with mixed success. Breaching calves are entertaining to watch, but there has been recent research suggesting that through repeated breaching, humpback whale calves increase the amount of myoglobin in their muscles. Myoglobin is a protein that binds iron and oxygen, and high concentrations of myoglobin can improve the diving ability of marine mammals.

There are a variety of possible explanations for why whales breach, but it is most likely that whales do not breach for any single reason, but rather do this behavior for a number of reasons that serve different functions throughout the seasons and over the course of their lives.

Written by Eilidh Milligan

Paddle Out For The Whales makes a splash in Australia

As part of the Hervey Bay Oceans Festival, our researchers had the opportunity to be involved in Paddle Out for the Whales–an event to help raise awareness of the threats whales face today. 

The event involved paddling out on a craft of your choice (SUP, kayak, inflatable raft, or handmade) to observe a minute of silence acknowledging the importance of whales and the ocean to Hervey Bay. Before the paddle out began, a live Zumba session got the paddlers loose and limber. One of our research volunteers, Jaimi, paddled out by kayak to participate in the event while Research Assistant Jessica remained on land to give an informative talk about PWF’s research in Hervey Bay. A PWF booth was present at the event to sell items from our Australia-based gift shop, as well as engage with community members about the research in Australia.  The event also featured live music, sandcastle building, and construction of a 6-foot papier mache whale.

Written by Eilidh Milligan

FACT OF THE WEEK: False Killer Whales Call Hawaii Home

MORE ON THIS: False killer whales, while a globally distributed species, have a special tie to Maui and the four-island region. Recent research has found that a very small group of this odontocete, or toothed whale species,  calls Hawaiian waters home, making them genetically different from offshore groups. This makes this population especially interesting because false killer whales are generally thought to prefer deep ocean environments far from any land.

Genetic tests were completed on samples collected from groups of false killer whales around the main Hawaiian islands and locations throughout the North Pacific. Researchers found samples collected from individual whales close to the Islands were most genetically unique when compared to samples from whales in the Pacific Ocean, Panama and Mexico. The uniqueness of the samples indicates there are two separate populations; an inshore population and an offshore population.

Their acrobatic displays and tendencies to bow ride make false killer whales hard to miss if you are lucky enough to see one. Hawaii insular population numbers are predicted to be as low as 123 individuals, with only 46 capable of breeding. There is good news though. The insular false killer whale population was classified as an Endangered Species in 2012, meaning this population now has extra protection. Keep your eyes open. If you’re lucky you will see one of Hawaii’s very own false killer whales.

FURTHER READING:

  1. Protecting Hawaii’s False Killer Whale. Pacific Whale Foundation. Accessed October 8, 2015
  2. Baird, R. (2009). A review of false killer whales in Hawaiian waters: biology, status, and risk factors. US Marine Mammal Commission: 1-40.
  3. Chivers et al. (2009). Genetic Variation and Evidence for population structure in eastern North Pacific false killer whales. Canadian Journal of Zoology, 85: 783-94.

Written by Chelsea Brown

FACT OF THE WEEK: Bio-Fluorescent Coral Flaunts Underwater Light Show

MORE ON THIS: It is easy to see the beauty of coral reefs when snorkeling or diving during the day, but have you ever seen the colors of coral at night?

Coral reefs are known to put on a light show known as bio-fluorescence.  A family of proteins provides this fluorescence by absorbing one color and emitting another.  Each protein provides a different color; the most common is the green fluorescent protein known as GFP.  When the wavelengths of color are absorbed then re-emitted, some of the energy is lost.  This changes the wavelength, which determines the color.

Species of coral known to give off this fluorescence are found in Hawai‘i and can be seen on night dives with special dive lights.  If you’re interested in seeing this phenomenon, you can contact your local dive shop to ask about night diving to see fluorescent coral or, if you’d like to stay dry, you can visit the Maui Ocean Center which has some of this coral on exhibit.

It is unknown why fluorescence occurs, but there are speculations from scientists.  Some believe that it acts as a sunscreen for the coral.  Researchers also have proposed that the fluorescence creates light to allow algae to grow in deeper water; algae is the major food source of most corals.

Research is focusing on coral fluorescence for several reasons.  The first reason is due to the fragile state of coral reefs in our climate-changing world.  Some studies suggest that the intensity of the fluorescence can be a sign that the coral is under stress and may indicate that the coral is about to bleach.

Medical research is also greatly benefiting from coral fluorescence research.  The same proteins the corals use to fluoresce are being used to help monitor biological processes within diseases to further understand how they work. This is done by using the fluorescence as a marker so scientists can watch cells divide or viruses spread.

FURTHER READING:

  1. Roach, John. 2005. “Glowing Coral Proteins Aid Medical Research.” National Geographic. http://news.nationalgeographic.com/news/2005/01/0112_050112_coralproteins.html
  2. Roth,  Melissa S., Fran, Tung-Yung, Deheyen, Dimitri D. 2013. “Life History Changes in Coral Fluorescence and the Effects of Light Intensity on Larval Physiology and Settelement in Seriatopora hystrix.” Plos One. http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0059476
  3. University of California – San Diego. 2013. “Fluorescent light revealed as gauge of coral health: Mysterious glow of light found to correlate with coral stress prior to bleaching.” Science Daily. www.sciencedaily.com/releases/2013/03/130312092918.htm.

Written by Sarah Mousel