Science SpotlightLearn about some of the fascinating topics being investigated by scientists at the Zoo.
Red Wolf Science
Sea Stars in Peril
RED WOLF SCIENCE:
How does reproductive research help a species survive?Dr. Ashley Franklin, PhD, is a Reproductive Biology Post-Doctoral Fellow. She helps maintain a Genome Resource Bank (GRB) – in this case, a collection of sperm samples – for the red wolf Species Survival Plan® (SSP).
Red wolves were on the brink of extinction just a few decades ago, with only 14 individuals remaining in the wild. The species has survived thanks to zoo-based research like Ashley’s. As of 2016, the population has grown to about 250 red wolves.
A dip in the (gene) poolTo prevent a population from going extinct, it’s important to consider the health of its gene pool. A gene pool is the complete set of all the genes making up a population; a diverse gene pool is a healthy one. When a species is represented by too few individuals, genetic diversity can be compromised by inbreeding.
Species Survival Plan® (SSP) Programs are managed by biology experts who keep track of which animals are breeding in order to ensure growth and diversity of zoo-based populations. The goal of each SSP is to ensure a healthy, genetically diverse population for at least 100 years.
Collecting and storing sperm is an important part of red wolf SSP research. The red wolf GRB currently has samples from 71 males from 1990 to present. The goal is to keep a variety of sperm in good condition so that samples can be used in artificial insemination.
Put it on ice
Sperm cells don’t naturally survive outside the body for very long. Like astronauts in a sci-fi movie, they need to be frozen and later thawed. But the freezing process is harsh and can cause damage. Sugars and certain mixtures called “cryoprotectants” help sperm endure the freezing process, allowing them to be stored for a long time.
Ashley has tested different types of sugars and cryoprotectants on red wolf sperm to see what offers the best protection against freezing damage. She found that glycerol works better than a chemical compound called dimethyl sulfoxide (DMSO), and that fructose – or a mixture of fructose and glucose – works better than glucose alone.
When Ashley checks samples under a microscope, she’s looking for a few things. First, a good percentage of the sperm should be moving – or “motile” – and they should be able to swim forward, not just in circles or side-to-side. Secondly, they should be a normal shape and size, free of abnormalities like coiled tails or small heads. Finally, a sperm cell needs to have a good “acrosome,” which looks like a beanie hat on the head of the sperm. The acrosome is a package of enzymes that helps it burrow into an egg, should it ever encounter one.
Timing is keyFor artificial insemination to work, a female red wolf needs to have produced an egg that is ready to be fertilized. Timing is very important when it comes to pregnancy.
The levels of various hormones help scientists determine when a female red wolf could become pregnant. The study of hormones and the glands that secrete them is called endocrinology.
Ashley checks female red wolves for a few types of hormones. Progesterone increases when a wolf is in estrus (“in heat”); estradiol increases leading up to estrus, then drops after ovulation. Ashley also conducted a study to see whether cortisol, a hormone associated with stress, influences red wolf cycles. Based on data from multiple zoos, she found that cortisol does not have an impact on red wolf estrus.
Looking to the future
The next step in this area of research, Ashley says, is to improve artificial insemination techniques. She plans to continue applying reproductive science and endocrinology in ways that promote species survival and animal health.
Reproductive biology is crucial to maintaining a healthy population of red wolves. Some red wolves have even been reintroduced to the wild, although wild populations are facing challenges. You can make a difference by contacting your representative and encouraging them to support laws that protect red wolf restoration in North Carolina.
Can we predict jellyfish abundance like we predict the weather?
Dr. Chad Widmer, PhD, thinks so. He’s an Aquarist at Point Defiance Zoo & Aquarium, and he’s interested in learning why jellyfish behave the way they do – and how we might use technology to understand them better in the future.
When Chad first started working with jellyfish at Monterey Bay Aquarium, he was responsible for keeping jellyfish tanks filled with thriving, healthy animals.
He has experimented with water temperature and salinity (salt level) to figure out the ideal water conditions for each species.
The circle of lifeWhat comes to mind when you picture a jellyfish? It’s probably a blob-like sea creature with a bell-shaped body and long, trailing tentacles. This is a jellyfish in the medusa stage, when it’s free to drift and swim around.
But there’s another side to the jellyfish life cycle. Before reaching the familiar medusa stage, jellyfish larvae attach to hard surfaces and mature into polyps.
Jellyfish polyps look like small sea anemones and can remain in this stage for a long time. They reproduce by creating juvenile jellyfish, or by budding off new polyp clones.
When does a polyp create more polyps – and when does it produce jellyfish?
As it turns out, this reproductive behavior depends largely on water temperature.
Jellyfish scienceIn the wild, mature jellyfish are often observed in groups called swarms, smacks, or “jellyfish blooms.”
On the Great Barrier Reef, certain jellyfish blooms can be predicted based on wind patterns. This is not because the wind affects the jellies’ life cycle; the wind merely stirs them closer to the surface, where people are more likely to encounter them.
Other environmental factors influence jellyfish abundance as well.
In his research, Chad has generally observed that warmer water causes polyps to create more polyps, while colder water results in the production of jellyfish.
What do jellyfish blooms look like?The Washington State Department of Ecology collects information about Puget Sound water conditions. They compile weather reports, chlorophyll measurements, aerial photos, satellite images, and other types of data to get a broad picture of what’s happening in our local waters.
The resulting Eyes over Puget Sound monthly report is packed with stunning aerial photos and fun facts about Puget Sound marine wildlife.
In these monthly reports, jellyfish blooms can be seen as long white streaks in the water. The jellyfish are congregated together because the wind moved the water in such a way that they were pushed into a group.
Climate change and jelliesAs Chad discovered in his research, water temperature influences jellyfish polyp reproductive behavior. Global climate change will almost certainly influence the abundance of jellyfish blooms in different locales.
Some say that an increase in sea temperatures means that jellies will take over the world’s oceans. In fact, some media sources are already reporting that jellyfish populations are on the rise. But there is not yet strong evidence for a significant global increase in jellyfish.
A limited understanding of jellyfish population cycles might contribute to this idea. Because polyps are hidden from view, changes in water temperature can have effects that won’t be observed until many months later.
And because wind patterns can push disparate jellies together into large clusters, photos that depict massive jelly blooms are not sufficient evidence for a worldwide increase in jellyfish populations.
More research is needed before scientists can make well-founded statements about global changes in jellyfish populations, and how their abundance is likely to change in response to climate variability.
Jellyfish forecastsChad envisions future research that involves aerial photos over the waters of the Puget Sound to reveal where jellyfish blooms are located. Remotely-operated underwater vehicles and cameras installed on wharf pilings would also give us a better glimpse into the distribution and everyday behavior of these mysterious animals.
By comparing jellyfish abundance to other data, like weather and water temperature, we can improve our understanding of how various factors affect jellyfish abundance in the Puget Sound. Eventually, with enough study, we hope to predict jelly blooms just as we predict the weather.
SEA STARS IN PERIL:
Can antibiotics help protect against Sea Star Wasting Syndrome?
Sea stars along the west coast, from California to Alaska, are being affected in record numbers by a mysterious condition known as Sea Star Wasting Syndrome.
The syndrome leaves them weak and susceptible to bacterial infection. The syndrome can cause arm curling, lesions, and eventually death. As the sea stars die, entire arms fall off and their bodies disintegrate.
Although the cause of the syndrome is unknown, many scientists are working to find potential treatments.
West Coast aquariums with open seawater systems (like Point Defiance Zoo & Aquarium, which pumps filtered water directly from the Puget Sound into aquarium tanks) are working together to learn more about the syndrome - and to develop techniques that might save aquarium populations in the meantime.
"We lost a significant number of our sea stars," said Melissa Bishop, an Aquarist at Point Defiance Zoo & Aquarium. "So we came up with a plan to see if we could treat some of them." Aquarium and veterinary staff took a collection of sea stars that showed signs of wasting and housed them in a separate tank where they were medicated with an antibiotic called Trimethoprim Sulfamethoxazole. This particular antibiotic was chosen partially because it treats a wide range of bacterial infections.
Although the antibiotic did not "cure" sea stars of the syndrome, it appears to knock back the infectious bacteria that are probably causing all the deterioration. This allows the animals to live longer. Some of the sea stars that were starting to lose arms were even able to regrow their limbs. That probably doesn't happen in wild sea stars affected by the syndrome, Melissa explained, because they deteriorate too quickly.
Looking to the future
Antibiotics are not a permanent solution. "Because we're an open seawater system, the affected stars start to get better as we do the baths, but when we stop, they deteriorate again," Melissa explained.
However, further research in this area will set the stage for future protocol in dealing with the syndrome when it hits aquarium populations.
Melissa presented her findings at the 2015 Regional Aquatics Workshop (RAW), where she was awarded a "Best of RAW" award. Congratulations to Melissa, aquarium staff, and veterinary staff for their hard work!