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A Perishing Predator: Polar Bears Starve as Ice Recedes

Authors: Samantha Abarca, Vincent Chevreuil, Ray Hunter

Polar bears. Just seeing the name conjures images of an enormous apex predator with fearsome canines and deep, black eyes, able to propel itself through snow and water with equal ease. Weighing up to 600kg, these beasts spend days on end searching for food in a sub-freezing oasis of barren ice (1). If a polar bear gets lucky, it can snatch a ringed seal with its narrow jaws  and razor sharp claws and sustain itself for a few days until the next victim is found (2). 

Unfortunately, this doesn’t seem to be the case anymore. As global warming continues on a seemingly unstoppable course, a domino-like chain of environmental effects is having devastating impacts on polar bear populations, leaving them poisoned, emaciated, and on a desperate search for declining food sources. Reduction of sea ice and viable prey, both of which are essential for polar bear survival, have made surviving the harsh Arctic conditions nearly impossible for these animals. The root of all these threats plaguing polar bears lies close to home - our cars, our agriculture, our consumer lifestyles, and the exorbitant waste products of material society. Polar bears have become hostages to our waste, and if we don’t hurry they may become victims to it as well. 

Polar bears are dependent on large sheets of floating arctic ice, and spend much of their time using the ice to move, hunt, and find mates (3). With warming sea temperatures, the sea ice habitat they depend on for survival melts away into the ocean, literally fragmenting their homes and their lives. They are forced to travel and swim further and further to find fat-rich prey. These longer migrations increase energy demand, forcing hungry polar bears deeper into energy deficits (4). Unlucky polar bears may not find food for themselves or their cubs, and may even starve to death (3). The lack of food and longer migrations result in the starving, emaciated images we now frequently capture of the once-proud polar bear.

In the arctic regions of the world, the presence of ice is crucial for the wellbeing of seal populations as well. Where there is ice, there are seals, and a reduction of sea ice means a similar loss in the polar bear’s favorite food, the Ringed Seal. Ice serves as a habitat and breeding ground for these seals, so as it melts, these seals experience a similar reduction as the polar bear (3). In this way, climate change dramatically alters the predator prey dynamics between seals and polar bears. Fragmentation of ice sheets pushes seals hunting grounds further and further back along the stable ice which in return alters travel behavior and foraging in polar bears. The polar bear’s high metabolic rates (due to increased travel) and declining food intake means that they end up fasting for longer stretches of time (5). What’s worse is that these limitations can even affect the next generation - mother polar bears may lack the energy to produce milk and bring back food to the den, leading to high infant mortality (3). In return, a declining population puts more stress on individuals to find mates and reduces the genetic variation in a given area. It acts as a sort of positive feedback loop in which increased arctic sea ice melt indirectly drives down polar bear populations in many other ways.

In the search for new food, polar bears have turned to warm-water fish species that have migrated up north with increasing temperatures. These fish act as “biovectors” for manmade pollutants; in other words, they are convenient edible packages of pesticides, preservatives, and industrial runoff (4). These fish spend their time in more southern waters where they are exposed to much of the artificial chemicals and pollutants that humans introduce into marine environments. The fish grow up feeding on these compounds and collectively building up large concentrations of these pollutants in migratory populations (4). Due to polar bears’ high metabolic rates, they need to consume many of these little poisoned swimmers to meet growing energy demands. As polar bears start feeding on this new food source, these pollutants concentrate in the malnourished polar bear’s thin body, and may ultimately become toxic to them when enough is consumed (4). It is even possible that these pollutants are transferred from mother to cub via milk which introduces these poisons to young ones directly after birth. These pollutants have proven to disrupt physiological processes in the body and the brain, impacting regulation, metabolism, and even reproductive behavior (4). Alongside with climate change, these compounds are drastically reducing polar bear populations to alarming low levels.

The good news about all of this is that it is not too late to do something. We are still at a point in time where global emissions can be reduced to counteract climate change and not hit a threshold of unstoppable positive feedback loops. The Intergovernmental Panel on Climate Change (IPCC) claims that we need to remain under 1.5 °C post industrial revolution temperatures to prevent the worst possible outcomes (6). Even though it may seem like hope is lost at times and there is not much that can be done at this point, we still have a very strong fighting chance to save not just ourselves, but all of the wildlife around us. Reducing your carbon footprint can make a big difference in the long run and set an example to those around you. Consuming less meat and dairy as well as driving less are two big ways to help at an individual level. Voting for people in office who care about climate change and take active initiative to combat it is absolutely crucial in reforming policies concerning the climate and endangered animals. We have a voice in the government, so vote responsibly for representatives that share a concern for the wellbeing of our world. Lastly, contribute to environmental organizations who lobby and make a stand against large corporations that contribute to climate change. Individually, these actions can seem inconsequential. But collectively, they add up to enormous positive changes to our world - and just might save some polar bears.

Image Credits:

flickrfavorites. “Snow on Snout, Polar Bear.” flickr.com, 2009, www.flickr.com/photos/38485387@N02/3582475670.

Weith, Andreas. “Starving Polar Bear.” wikipedia.com, 2015, www.wikipedia.org/wiki/File:Endangered_arctic_-_starving_polar_bear.jpg.

All images shown are free to share under a Creative Commons license.


Citations

  1. I. Stirling, Polar Bear: Ursus maritimus. In Encyclopedia of Marine Mammals (pp. 888-890). Academic Press (2009).
  2. C. Freitas,  K. M. Kovacs, M. Andersen, J. Aars, S. Sandven,  M. Skern-Mauritzen, C. Lydersen, Importance of fast ice and glacier fronts for female polar bears and their cubs during spring in Svalbard, Norway. Marine Ecology Progress Series, 447, 289-304 (2012).
  3. P. K. Molnár, A. E. Derocher, G. W. Thiemann, M. A. Lewis, Predicting survival, reproduction and abundance of polar bears under climate change. Biological Conservation, 143(7), 1612–1622 (2010).
  4. B. M. Jenssen, G. D. Villanger, K. M. Gabrielsen, J. Bytingsvik, T. Bechshoft, T. M. Ciesielski,  R. Dietz. Anthropogenic flank attack on polar bears: interacting consequences ofclimate warming and pollutant exposure. Frontiers in Ecology and Evolution, 3 (2015).
  5.  A. M. Pagano, G. M. Durner,  K. D. Rode, T. C. Atwood, S. N. Atkinson, E. Peacock, T. M. Williamsc. High-energy, high-fat lifestyle challenges an Arctic apex predator, the polar bear. Science, 359(6375), 568–572 (2018).
  6. “Summary for Policymakers of IPCC Special Report on Global Warming of 1.5°C Approved by Governments.” IPCC Summary for Policymakers of IPCC Special Report on Global Warming of 15C Approved by Governments Comments, 2018.

I

Ape Eviction? These Orangutans are losing more than their homes.

Authors: Avery Laing, Kenneth Peterson, Jahan Sandhu, Katie Whitcomb

Orangutans, meaning “people of the jungle”, are a unique and charismatic keystone species in the rainforests of Borneo. These primates are in danger and it isn’t a disease, natural disaster, or invasive competitor; it’s human consumerism. Palm oil is the most widely-used oil in the world, and over 80% of the trees it comes from are found in the rainforests where orangutans live. Excessive deforestation has led to mass habitat destruction for these defenseless primates. And this habitat loss has effects just beyond losing a place to sleep. Displaced orangutans are struck by food scarcity, developmental trauma, and stunted growth. These factors all play into a mass population decline. Here we follow the story of a young male orangutan named “Pongo” to get a first-hand look at how these struggles affect an individual in the course of his life.

Pongo swings through the trees of Borneo’s lowland rainforest with his sister and his mom for some breakfast. They are going to have the usual meal of fruits. Eating fruit is a part of orangutans being keystone species, or species that indirectly affect their environment in pivotal ways. Pongo and his family help spread the seeds of the fruit they eat so that many species of fruit-bearing trees can survive in the jungle. When the seeds are consumed by orangutans, the chemicals inside of their digestive system germinate the seeds. As Pongo makes his way to his favorite tree, the durian fruit tree, he notices something is off. Many of the trees along the usual route seem to have most of their branches stripped, while other trees are just missing entirely. Ever since the humans and their machines came, the jungle has just not been the same. As Pongo and his sister get closer to the prized durian tree, the density of the forest starts to thin. Thankfully, their mom is there to help them give the extra weight needed to swing from tree to tree. Mothers raise their young for 8 years on average until they reach adulthood and separate from the mom, so she can find a new mate. They all finally make it to the durians and begin to feast on the nutritious fruits. As the happy family eats, the mom notices sounds emerging from the distance. She tells Pongo and his sister to stay in the tree while she goes to scout and see if there is a potential threat. Pongo and his sister race to the top of the tree to eat more fruit. As they satisfy their hunger they try to swing over towards the tree their mom went to. The only problem is that the trees now have more space in between them than before, and without the help of their mom, they have no way of getting over. The only thing they have to do now is wait for their mother’s return. 

Hours pass by and Pongo’s mom hasn’t returned yet. Pongo starts to feel stress as this has never happened before. Again, the only thing he and his sister can do is wait, so in the meantime, more durian fruits are snacked on. It has been a few days and Pongo and his sister are still stranded in the tree. Needing to take measures in their own hands, the siblings climb down from the tree in search of water. Moving around on the ground is much more dangerous for orangutans than moving through the trees. Orangutans have long arms to help them move through the trees swiftly, but with scarce forest due to human interference, moving on ground is their only option. As Pongo and his sister trek through the forest, they start to get hungry again and fruit is no longer an option. Fruit scarcity is a major problem for Orangutans as they are deprived of their main source of nutrients. As Pongo and his sister failed to find the fruit they were searching for, they turned to bark and leaves as fallback foods. Pongo and his sister ate bark and leaves while missing their mom and the delicious durian fruit. A couple more days passed by and all they found while trekking on the ground was bark and leaves which made them feel extremely weak and malnourished. During chronic periods of food, scarcity orangutans are able to digest their own fat reserves, despite having very low metabolic rates, which leads to major malnutrition. Pongo and his sister entered a period of near starvation, unable to get the nutrients that they needed. As their territory is decreasing and the many trees with fruits are disappearing, Pongo and his sister are on the brink of death by starvation, unable to get the protein that their bodies need.

Fully developed male Orangutan

 

Defying all odds, Pongo has scraped and struggled to survive and now enters adolescence. Perhaps his life will become a little easier as he grows larger and is able to claim his stake in the jungle. But the problem here is that Pongo may not grow much at all. Another effect of decreasing territory is perhaps the most unexpected. As habitable areas shrink it causes orangutans to live closer together. Recent research has shown that young male orangutans actually don’t fully develop when in high-stress situations caused by the close presence of aggressive adult male orangutans. This is a “ negative socio-endocrine phenomena” which is just a fancy way of saying the body doesn’t produce the right chemicals it needs to develop when growing in a stressful environment. Pongo may become stunted because he’s too stressed, and not have the opportunity to develop into a fully-fledged male.

This stunted growth found in arrested males stops them from developing secondary characteristics that are found in mature males. These characteristics include larger body size, large cheek disks, and a sac located on the individual’s throat. So what causes these developmental differences and which one will be the most beneficial to Pongo’s survival? These developmental routes are all due to the presence and absence of hormones! The reason behind why some males lack secondary traits is due to the suppression of a hormone known as dihydrotestosterone (DHT), which plays a role in puberty and triggers male characteristics. When viewing hormonal levels of males with secondary traits, DHT levels are of high significance. Now knowing the science behind how these developmental processes work, the question of which body type is best can be answered. Both developmental routes come with their own costs and benefits that can be the deciding factor of young Pongo’s success. If his environment does not incite secondary characteristics, Pongo will become a “sneaker male”. These males resemble females, enabling them to hide from large, dominant males so they can sneakily mate with females. The benefit of being a sneaker male is that Pongo will not have to spend energy on developing and maintaining those secondary traits; however, he will also face a cost by not being preferred by females and will struggle to mate. If Pongo does develop secondary traits, mating will be highly successful as he is the female’s preference. The downfall, however, is that he will not only have to maintain large body size, but he will also be frequently involved in territorial combat against other males. These natural developmental processes are already stressful enough, but now Pongo will face an even greater amount of stress due to the deforestation of his habitat. By destroying Pongo’s home, he and many males alike will most likely be forced to develop as sneaker males in order to survive their loss of habitat. 

Pongo’s situation is actually becoming a very common issue in today’s world. All of the dangers and stress that Pongo faced represent real-life dilemmas that orangutans deal with. The issues revolve around the main problem, palm oil extraction. The deforestation of palm trees restructure the layout of rainforests and cause a variety of issues previously stated. Many studies about Orangutans have taken place in conservatories where orangutans are held captive. We can learn a lot about them through studies done in these research areas but lack information about how these results translate to wild populations. Orangutans are an endemic species that only reside in the rainforests of Sumatra and Borneo. Spreading awareness of these anthropogenic dangers to this group of primates is a start to saving this valuable species. Palm oil consumption is the biggest contributor to why deforestation in these jungles has happened in the first place. We can help prevent deforestation by decreasing the amount of palm oil we consume. Buying fewer items that contain palm oil, or finding substitutes, can help one in doing their part to fight against the palm oil industry. As consumers, we are lucky to have a degree of control over what products we buy. More info about palm oil and ways to help can be found here. For the future of these primates, and the ecosystems they support, we must band together and use our collective power to make choices that support the environment and orangutans like our dear friend Pongo.

 

Photo Credits:  

Deforestation caused by Palm oil harvest, provided by Pixabay

Fully developed male Orangutan, provided by National Geographic (September 2018)


Citations

  1. A. N. Maggioncalda, R. M. Sapolsky, N. M. Czekala, Reproductive hormone profiles in captive male orangutans: Implications for understanding developmental arrest. American Journal of Physical Anthropology, 109 (1), 19–32 (1999). 
  2. R. S. Mendonça, R.S.C. Takeshita, T. Kanamori, N. Kuze, M. Hayashi, K. Kinoshita, H. Bernard, T. Matsuzawa, Behavioral and physiological changes in a juvenile Bornean orangutan after a wildlife rescue. Global Ecology and Conservation, 8, 116–122 (2016).
  3. D. L. A. Gaveau, S. Wich, J. Epting, D. Juhn, M. Kanninen, N. Leader-Williams, The future of forests and orangutans (Pongo abelii) in Sumatra: predicting impacts of oil palm plantations, road construction, and mechanisms for reducing carbon emissions from deforestation. Environmental Research Letters, 4 (3), 034013. doi: 10.1088/1748-9326/4/3/034013 (2009). 
  4. A. N. Maggioncalda, N. M. Czekala, & R. M. Sapolsky, Male orangutan sub adulthood: A new twist on the relationship between chronic stress and developmental arrest. American Journal of Physical Anthropology, 118 (1), 25–32 (2002). 
  5. E. R. Cheryl, B . E. Crowley, M. D. Blakely, M. D. Larsen, N. J. Dominy, Bornean orangutans on the brink of protein bankruptcy. The Royal Society, 8 (3), (2011).
  6. “Orangutans.” National Geographic, 24 Sept. 2018, www.nationalgeographic.com/animals/mammals/group/orangutans/.
  7. “The Effects of Palm Oil.” Official Orangutan Foundation International Site, orangutan.org/rainforest/the-effects-of-palm-oil/.
  8. Dewan, Angela. “Borneo's Orangutan Population Slashed by Half in 16 Years.” CNN, Cable News Network, 16 Feb. 2018, www.cnn.com/2018/02/16/asia/borneo-orangutan-population-decline-intl/index.html.
  9. "Fully developed male Orangutan." Pixabayhttps://pixabay.com/photos/deforestation-forest-wood-cut-405749/

Are We Clogging the Ears of Humpback Whales?

Author: Madison Jacobs-Morris

Have you ever wondered how a huge animal that lives in such a vast habitat could be on the endangered species list? Well, humpback whales have a gruesome history and are still reaping the effects today. Hunters in the 20th century killed between 20,000 and 40,000 humpbacks during the whaling era (1). Anthropogenic, or human-caused, disturbances are inflicting harm to many species across the globe. Historic whaling increased stress levels greatly, and even nearly 50 years after the Marine Mammal Protection Act, stress levels are still higher than pre-whaling levels. 

 

Impact of Cortisol Levels

Baleen whales have a buildup of earwax layers within their ear canal called earplugs (2). The buildup in earwax actually aids in hearing, rather than disrupting it (3). The earwax forms layers, similar to the rings in a tree trunk, that show age, hormone levels (2), and pollutants (4) during their lives.  The increase of stress levels during and after the whaling era can be seen in the earplugs by measuring cortisol levels (2). Cortisol levels can be dated to see at what point spikes occurred and how long they were increased (2). A chronic increase in cortisol levels can have many adverse effects in animals including being more vulnerable to disease, changes in nervous system, reproductive, and metabolic functions, and stunts with growth and development (5). The effect of whaling caused heightened cortisol levels, not only during the whaling era, but was also passed down through generations (2). Therefore, we can still see the effects that whaling had on the species. 

 

Other Impacts

While humpback populations are making a steady recovery towards pre-whaling numbers, other factors could reverse this. Humpbacks feed in polar regions, and increasing sea surface temperatures are causing sea ice melt, decreasing prey populations (6) and increasing cortisol levels as seen in this paper. Humpbacks are also great indicators of other disturbances to the environment because they are considered sentinels, or animals that can accumulate pollutants in their tissues without serious effects (7). The accumulation of pollutants can be seen in their earplugs as well. The pollutants can have toxic and adverse effects to animals’ immune systems, nervous system, development, and can cause tumors, permanent changes in DNA, and issues with hormone production through the endocrine system (8). 

 

Modern Whaling

While the International Whaling Commission has banned whaling, Japan has left the commission and continued with hunting whales. To learn more about this, click here. Iceland also continued commercial whaling in 2006, but as of 2020 have decided to halt the hunting of whales as the whale watching industry is booming in the country. More information is available here. In addition, whale hunting is a significant part of many indigenous cultures and is mostly handled by the International Whaling Commission. To read a very informative article about the significance of whaling for indigenous communities in Alaska, Greenland, Russia, Grenadines, and Canada, click here.

 

Future Implications and How to Help

While they’re still on the endangered list, humpbacks have really rebounded from the brink of extinction. While we can’t reverse the impacts of historic whaling, we can work to protect humpbacks and ensure their populations keep growing. The Pacific Whale Foundation created a list of 40 ways to save the whales, including petitioning to keep them on the endangered species list,  reducing your CO2 emissions to help slow sea surface temperature rise and ocean acidification, sharing pictures of whale flukes to help build a database of population numbers, support Marine Mammal Protected Areas, use eco-friendly cleaning products, reduce the used of plastic grocery bags, and get involved in educational and volunteer programs. 


Citations

1. L. Nemo, (2019, November 18). From 440 To 25,000: One humpback Whale Population's Amazing recovery. Retrieved May 15, 2021, from  https://www.discovermagazine.com/planet-earth/from-440-to-25-000-one-humpback-whale-populations-amazing-recovery

2. S. J. Trumble, S. A. Norman, D. D. Crain, F. Mansouri, Z. C. Winfield, R. Sabin, S. Usenko, Baleen whale cortisol levels reveal a physiological response to 20th Century whaling. Nature Communications, 9, (2018). 

3. M. Chen, (2018, May 09). Whale earwax: What you can learn from strange collections. Retrieved May 15, 2021, from https://ocean.si.edu/ocean-life/marine-mammals/whale-earwax-what-you-can-learn-strange-collections

4. Z. C. Winfield, F. Mansouri, C. W. Potter, R. Sabin, S. J. Trumble, S. Usenko, Eighty years of chemical exposure profiles of persistent organic pollutants reconstructed through baleen whale earplugs. Science of The Total Environment. 737, 139564 (2020). 

5. J. F. Leatherland, M. M. Vijayan, N. Aluru, “Stress Response and the Role of Cortisol” in Fish diseases and disorders (Wallingford, UK, ed. 2, 2010), pp. 182-201.

6. M. P. Simmonds, W. J. Eliott, Climate change and cetaceans: concerns and recent developments. Journal of the Marine Biological Association of the United Kingdom. 89, 203–210 (2009). 

7. A. Beeby, What do sentinels stand for? Environmental Pollution. 112, 285-298 (2001). 

8. M. Nadal, M. Marquès, M. Mari, J. L. Domingo, Climate change and environmental concentrations of pops: A review. Environmental Research. 143, 177-185 (2015).

 

Photo Credit: 

Storck, A. (1690). Dutch whalers near Spitsbergen [Painting]. Stichting Rijksmuseum het Zuiderzeemuseum. Public Domain, retrieved from https://commons.wikimedia.org/wiki/File:Walvisvangst_bij_de_kust_van_Spitsbergen_-_Dutch_whalers_near_Spitsbergen_(Abraham_Storck,_1690).jpg

National Marine Sanctuaries (2013). A female Humpback whale with her calf [Photograph]. CC BY 2.0, retrieved from https://commons.wikimedia.org/wiki/File:Humpback_whale_with_her_calf.jpg. https://creativecommons.org/licenses/by/2.0/legalcode no changes were made.

Baleen Whales - The Oceans' Gentle Giants

Author: Shena Cannon

Baleen Whales

While being the largest animals on earth, yet consume some of the smallest animals. There are 15 species of baleen whale, they are generally larger than toothed whales except for the sperm whale which is very big and has teeth. Many baleen whales migrate annually, traveling long distances between cold water feeding areas and warm water breeding areas. They can grow up to 90 feet, yet krill, small fish, and plankton sustain them. These creatures are the baleen order of whales, they have no teeth. Instead, have baleen which is a filter-feeding system that allows them to trap their favorite prey. Baleen is made out of keratin, it is the same protein that our hair and fingernails are made from. Baleen whales have been subjected to numerous anthropogenic disturbances, including whaling, ship strikes, and pollutants. These anthropogenic disturbances can cause an extreme stress response in mammals. According to Nature Communications, the physiological response to a stressor, defined as the disruption of an organism’s internal environment, or homeostasis, can lead to system-wide health effects from the scale of an individual to the population (3).

Stress Response

So what can cause baleen whales to be stressed? Cortisol is a stress hormone that is stimulated through the hypothalamic-pituitary-adrenal, this causes a stress response to activate in mammals and positively correlates with the severity of the stressor. Earplugs from baleen whales that consist of lipid and keratin-based semiannual bands of alternating dark and light laminae (growth layer groups) formed over the life span of the animal. By using the earplugs from baleen whales it determines the association of past and/or present anthropogenic stressors. According to Nature Communications, a positive relationship between activities associated with commercial whaling harvests and baseline-corrected cortisol from baleen whale earplugs spanning the 20th century (3).

Whale Hunting

For thousands of years, whaling has caused a lifetime of stress for baleen whales in the Northern Hemisphere. They were hunted and killed for different things including soap, jewelry, transmission oil, and margarine to corset material. With it being no controls on hunting, all these species eventually became depleted. Until 1982 when the International Whaling Commission “instituted a moratorium on commercial whaling and although some whale populations have since recovered to near their pre-whaling abundance, others remain compromise” (1). Most countries have stopped whaling activity.

Future of Baleen Whales

Whales are extremely important in the health of our environment and play an important role to help grow economies that rely on whale watching and other activities through tourism. Whales help the environment and the ocean’s ecosystems, regulating the flow of food to maintain a stable food chain and ensure certain animal species do not overpopulate the ocean. Even whale poop plays a large role in the environment by stabilizing the offset of carbon in the atmosphere and provides a healthier environment for both land and aquatic life forms. Whale watching has become a huge tourism activity; to get a glance at these majestic creatures in their natural habitat people have been spending billions of dollars. The growing interest in whale watching is an extremely important component for economies that want to increase their global presence and attract the interest of other countries. To conclude, whales not only play a vital role in the marine ecosystem by providing at least half of the oxygen we breathe, combat climate change, and sustain fish stocks but by following the Be Whale Wise Guidelines and giving whales the space they need and how to protect our oceans from the various forms of pollution can help these animals flourish once again.


Citations

(1) Brüniche-Olsen, A. et al. The inference of gray whale (Eschrichtius robustus) historical population attributes from whole-genome sequences. BMC Evolutionary Biology 18, (2018).

(2) Lapidese, J. Baleen Whales – The Gentle Giants of the Ocean. Oceanwide Expeditions (2018). Available at: https://oceanwide-expeditions.com/blog/baleen-whales-the-gentle-giants-of-the-ocean. (Accessed: 12th May 2021).

(3) Trumble, S. J. et al. Baleen whale cortisol levels reveal a physiological response to 20th-century whaling. Nature Communications 9, (2018).

Photo Credits

File:Humpback stellwagen edit.jpg by Whit Welles is licensed under GNU Free Documentation License and CC BY 3.0.

 

Be Kind to Your Neighbor: the California Sea Lion

Authors: Rachel Apolinario, Nicole Crawford, Maia Cymerys Da Silva, Ze En Ling

If you’re enjoying a day at the beach anywhere in California, you’ve probably come across some Zalophus californianus, or as they are more commonly known, the California sea lion. It’s especially hard to miss them in Santa Cruz. Whether you are at the beach, getting lunch on the wharf, or going on rides at the boardwalk, you have likely seen or heard these large marine mammals barking at each other or basking in the sun. It is common to see the larger, dark colored male California sea lion surrounded by the smaller tawny brown females, lounging around remote areas or tourist attractions; really, wherever there is an available rock. It’s hard to imagine Santa Cruz without them, they’re simply everywhere.

But have they always been so abundant?

California sea lion populations have recently rebounded to new heights as of 2018, ever since their populations dropped after 2012. Due to an unusually strong climatic and oceanic El Niño event combined with the emergence of “The Blob”, the waters of the Pacific Ocean along the west coast rose in temperature. Because of this climatic anomaly, thousands of California sea lions pups had their immune systems weakened from malnutrition. According to the National Oceanic and Atmospheric Administration , the California sea lion population dropped to 250,000 in 2014. You can read more about how El Niño affects marine mammals in this journal(1).

But thanks to the Marine Mammal Protection Act (MMPA) and the passing of El Niño and “The Blob”, California sea lion populations are now healthy and abundant, thriving along the Californian coast at areas of coastal upwelling such as Santa Cruz.

But the more important question to ask here - will the California sea lions stay this abundant? Anthropogenic threats of environmental pollution and interference from human activity are unfortunately why we need to ask this question. 

We contribute to a stressful environment more than we realize. It’s tempting to approach a California sea lion once you spot one in the wild, but have you ever considered how your presence, even just standing there, affects them?

Consistently being harassed by any species can be very stressful, and it can lead to changes in physiology and even death. In general, human contact with California sea lions have more negative than positive impacts. Human disturbances in this context is defined as any human exposure within 50m of the animal. With an increase of human disturbances like ecotourism and boating, important factors for California sea lion population growth such as reproductive rate begin to decline. Although studies may show increases in other factors such as pup growth rate, this can possibly be attributed to more indirect consequences from human exposure. More information on human disturbance influencing California sea lion reproduction can be found here (2).

It’s not just direct human contact putting these animals at risk.

California sea lions, like all marine life, can be affected by changes to our oceans’ conditions. Eutrophication, an excessively high nutrient load in the water, can be caused by agricultural runoff. This can promote massive amounts of algae growth in water. In large quantities certain algal blooms can produce toxins which can negatively affect the health of the entire marine system. During ENSO (also known as El Niño) years, the water conditions favor these algae blooms, with high nutrient loads and warmer water temperatures. The toxins that the algae produce work their way up the food web ultimately accumulating in top predators, such as California sea lions. This toxin (known as domoic acid) can cause reproductive and developmental damage, as well as brain damage. This article goes further in depth on this toxin (3).

From 1998 to 2002, 209 pregnant female California sea lions were stranded due to algae blooms from eutrophication in the Monterey Bay. Of these stranded females, less of half of them survived, but not after suffering from abortion or reproductive failure to toxins from the algae. The Marine Mammal Science journal has an article on this topic that provides further information and details here (4).

Although the impacts of our actions indicate that we can be a threat to California sea lion population growth, there is still so much we don’t know. Future studies should focus on how changes in their environment, anthropogenic or not, affect the physiology of these marine mammals. With evidence of the negative consequences of direct and indirect human disturbances one thing is clear - we have to do something.

While all of this current research may seem quite daunting and out of our hands, there is actually a lot we can do to help our sea lion friends! Here are a few “quick” tips:

If you eat seafood, checkout the Monterey Bay Aquarium’s seafood watch program! They make it easy to be a responsible consumer! This guide provides the reader with tools to choose the best fish for your health and the ocean’s.

Reduce your ocean footprint! Here are some simple ideas courtesy of The Marine Mammal Center:

    • Reduce the toxins you put into the environment, as these will runoff into our waterways and oceans. This can be done by managing what you pour down the drain or changing the type of fertilizer you use for gardening.
    • The most common items found trashing our oceans are plastic based! Choose reusable items over single use ones and recycle the plastic if possible.
    • Buy items in bulk to reduce packaging waste.
    • Bring your own reusable water bottles and mugs with you instead of single use plastic bottles.
    • Cut apart plastic soda can rings before disposal.
    • In general, just recycle everything you can!

If you encounter a California sea lion (or any marine mammal for that matter) please remember:

    • Leave them alone! Do not approach any marine mammals as they are wild and also protected under the MMPA. (keep your pets away too!)
    • If you are concerned about the health of a (living) marine mammal please contact the Marine Mammal Center (415-289-SEAL). If you come across a deceased or stranded marine mammal be sure to contact your local stranding network (831-212-1272 for Santa Cruz Area)
      • Both of these organizations operate under special permits that allow them to assist our friends in need and to collect data on deceased animals for science and their conservation!

With all of this information in mind, we hope that we have provided you with the tools to be kind to the locals (California sea lion) and help your local populations persist naturally! California sea lions play an important role in their ecosystem, making their conservation ever important to maintaining our local ocean health. Do your part! And be a good neighbor.


Citations

(1) Banuet-Martinez, W. Espinosa de Aquino, F. R. Elorriaga-Verplancken, A. Flores-Moran, O. P. Garcia, M. Camacho, K. Acevedo-Whitehouse, Climatic anomaly affects the immune competence of California sea lions. PLoS One. 12, 1-14 (2017).

(2) S.S. French, M. González-Suárez, J. K. Young, S. Durham, L. R. Gerber, Human disturbance influences reproductive success and growth rate in California sea lions (Zalophus californianus). PLoS One. 6, 1-8 (2011).

(3) C. A. Scholin, F. Gulland, F. M. Gulland, Mortality of sea lions along the central California coast linked to a toxic diatom bloom. Nature. 403, 80-84 (2000).

(4) E. C. Brodie, F. M. D. Gulland, D. J. Greig, M. Hunter, J. Jaakola, J. S. Leger, T. A. Leighfield, F. M. Van Dolah, Domoic acid causes reproductive failure in California sea lions (Zalophus californianus). Marine Mammal Science. 22, 700-707 (2006).

Image Credits

https://search.creativecommons.org/photos/d7aca214-dc1b-487a-8607-7621680b39ea

https://search.creativecommons.org/photos/fe916502-5425-4fba-b0ed-d671b8a86e30

 

Can Sockeye Salmon Outswim Climate Change?

Author: Dahlia Shammas

INTRODUCTION

Sockeye salmon, also known as Oncorhynchus nerka, are very unique animals. They have a distinctive and prehistoric look, as well as a unique lifestyle. They are well known for their strenuous and dangerous journey back to their home stream to spawn (lay and fertilize eggs). This journey is hard enough for sockeye salmon because of predation and how much energy it takes to travel upstream to spawn. Now, anthropogenic (human-caused) climate change has presented another challenge for sockeye during migration. Climate change has led to increased river temperatures in the summer during salmon migration, changing their behavior, physiology, and mortality rates.(1)

Sockeye salmon play an important role in the lives of many species, including ours. They are economically, culturally, and ecologically important. They are one of the most commercially fished species in British Columbia, Canada, and Alaska, United States.(2) They are also culturally very important to the St'át'imc people, the original inhabitants of Fraser River in British Columbia. Sadly, climate change has had negative impacts on how they traditionally fish and preserve sockeye.(3) Ecologically, they are a highly nutritious food source for many animals including bears, birds, wolves, sharks, fish, and other marine mammals. Some species like bears rely on sockeye salmon as a crucial source of energy. Additionally, their carcasses provide nutrition to animals and valuable nutrients such as nitrogen and phosphorus to the environment.

Sockeye salmon are found along the west coast of North America in the Northern Pacific Ocean. This blog post will focus mainly on sockeye salmon that inhabit Fraser River in British Columbia, Canada. Both male and female sockeye salmon look similar in size and color. Males are slightly brighter in color and have a large dorsal hump as can be seen in the photo above. Both sexes range in size from 20 to 28 inches.(4) Most sockeye salmon are anadromous, meaning they are born in freshwater rivers or lakes, travel to the ocean where they spend most of their adult life, and then travel back to their home stream to spawn. In freshwater, their diet consists of zooplankton, amphipods (shrimp-like creatures), and insects.(5) After migrating to the ocean they continue to feed on zooplankton but also eat fish and the occasional squid.(5) After birth, they mature in freshwater for one to three years before migrating to the Pacific ocean. After two to three years in the ocean, they migrate back to their home stream to spawn.(5) Most sockeye start this migration in June and July. Their spawning time varies depending on the population and can take place anywhere between June and December.(5) When they reach their home stream, females dig holes known as redds with their tails and deposit between 2,000 to 4,500 eggs.(5) Males often compete to fertilize the eggs and the females then cover them up with gravel to protect them from the elements and potential predators. After spawning only once, the salmon have fulfilled their lifetime reproductive duty and usually die within weeks.

This blog post will elaborate on how climate change is affecting sockeye salmon behavior, physiology, and mortality. Warmer river temperatures have advanced the timing of their migration to spawn by at least two weeks.(1) Warmer waters have also led to physiological adaptations at the population level for these harsher conditions as well as cardiac collapse when temperatures get too high.(6) A rise in parasitic and fungal infections is also seen in higher water temperatures which could lead to decreased fitness and death.(1) Increased temperatures are also correlated with higher mortality rates of adult salmon as they migrate upstream back to their spawning grounds.(6)

 

BEHAVIORAL CHANGE

Some sockeye salmon populations are migrating earlier to their spawning grounds because of warmer river temperatures in the summer caused by climate change.(1) Historically, populations of salmon start the migration to spawn in the summer around the same time, rarely changing that timing by more than a week.(1) Many populations exhibit a holding behavior, where they rest for 2-6 weeks in the Strait of Georgia (close to the Fraser River) before continuing their journey upstream.(1) Since 1995, this holding behavior has been abandoned by many populations of salmon.(1) Instead, these populations of sockeye advance their migration upstream by 2-8 weeks, significantly increasing the amount of time spent in freshwater compared to historical populations.(1) This is because their population-specific spawning dates do not change even though their migration time has advanced by at least two weeks.(1) This behavioral change in migration is cause for concern because early river entry has been associated with high levels of mortality ranging from 60%-90%.(1)

 

PHYSIOLOGICAL ADAPTATION

Rising river temperatures have had significant impacts on the physiology of sockeye salmon. Salmon burn energy quicker, could have increased stress levels, and possibly die if the water temperature gets too high. Some sockeye populations have developed physiological adaptations that allow them to better survive in higher temperatures. These cardiorespiratory adaptations include greater aerobic scope, increased heart size, and improved coronary supply.(6) A greater aerobic scope is defined as the increased capacity of oxygen consumption of an animal during exercise. Coronary supply is the rate at which oxygenated blood is pumped to the heart. These cardiorespiratory adaptations are different among populations in the Fraser River.(6) Each population of sockeye salmon has a different tolerance to temperature. This physiological limitation is possibly due to cardiac collapse caused by increased temperatures.(6)

 

SOCKEYE SALMON MORTALITY AND LOWERED FITNESS

Climate change has significantly raised the mortality rates of sockeye salmon during migration. As previously mentioned, warmer river temperatures have caused some salmon to prematurely migrate upstream to spawn. Early-entry salmon populations have elevated mortality rates from 60%-90% as a direct cause of historically higher migratory temperatures.(4) Exposure to higher river temperatures can result in the quick depletion of energy reserves that salmon rely on when they stop feeding during migration.(1) These reserves are crucial for spawning and if they are used too early exhausted salmon will not successfully reproduce, lowering fitness (the ability to produce viable offspring).(1)

Warmer water temperatures because of climate change also promote parasitic and external fungal infections in sockeye salmon.(1) An example being the parasite Parvicapsula minibicornis, which is found in the kidney.(1) This paper states that the infection rate of this parasite dramatically rose in sockeye salmon populations that experienced an increase in river temperature. It was also noted that warm-treated salmon (18°C) had more external fungal infections than cold-treated salmon (10°C).(1) A rise in parasitic and fungal infections can lead to increased mortality rates among sockeye salmon. The mechanisms by which they do this are not yet clear, but it is shown that they lead to increased metabolic stress and overuse of energy stores. This lowers overall fitness and could ultimately lead to death.

 

CONCLUSION

Climate change has increased temperatures in rivers where sockeye migrate, causing behavioral change, physiological adaptation, and increased mortality rates at the population level. Warmer water temperatures can advance the river entry time of salmon populations, increasing mortality rates by 60%-90%. Some sockeye populations have developed physiological adaptations that improve cardiorespiratory performance in warmer river conditions. Additionally, high water temperatures can lead to death because of cardiac collapse. Rising temperatures also increase parasitic and fungal infections, which can lead to decreased fitness and increased mortality rates. Exposure to warmer waters lowers the overall chance of survival and reproduction of some sockeye salmon populations. This is particularly concerning for salmon because they only reproduce once in their lifetime. If their health is threatened on their journey to spawn they might not ever successfully reproduce.

Some efforts are being made to conserve sockeye salmon populations. An article by The Nature Conservancy stated that in Alaska, streams are being restored from damage caused by logging. Alaskan rainforests are also being restored by the Hoonah Native Forest Partnership.(7) This is beneficial to salmon because they need strong tree roots in river banks for stability, shade, and protection. There are also multiple organizations educating the public about sockeye salmon and how humans threaten them.(7) Researchers at the Eagle Fish Hatchery of the Idaho Department of Fish and Game are also working hard to preserve sockeye salmon populations. Their goal is to change from a hatchery-based recovery system to one that relies more on salmon reproduction in the wild. They want to ultimately avoid the extinction of sockeye salmon and support sport and tribal harvest needs. More about their efforts can be read here.

A lot is still unknown about how climate change affects sockeye salmon. The environmental factors that influence migration should be further explored. More research should be done to see if sockeye salmon as a species are changing their migratory behavior in a beneficial or harmful way. How parasitic and fungal infections increase mortality rates in sockeye salmon should be investigated. Specifically, the impacts of the parasite Parvicapsula minibicornis on energy use and kidney function. Additionally, it is very important to determine whether sockeye salmon can physiologically and behaviorally adapt in time in order to survive and eventually thrive in increasing river temperatures. Hopefully, through continued research and conservation efforts, sockeye salmon will be able to adapt and “outswim” the negative effects of climate change.


Citations

  1. Crossin GTCT, Hinch SGHG, Cooke SJCJ, Welch DWWW, Patterson DAPA, Jones SRMJRM, et al. Exposure to high temperature influences the behaviour, physiology, and survival of sockeye salmon during spawning migration. Can J Zool [Internet]. 2008 Feb 18 [cited 2021 Apr 23]; Available from: https://cdnsciencepub-com.oca.ucsc.edu/doi/abs/10.1139/Z07-122
  2. Sockeye Salmon [Internet]. Oceana. [cited 2021 Apr 23]. Available from: https://oceana.org/marine-life/ocean-fishes/sockeye-salmon
  3. Jacob C, McDaniels T, Hinch S. Indigenous culture and adaptation to climate change: sockeye salmon and the St’át’imc people. Mitig Adapt Strateg Glob Change. 2010 Dec 1;15(8):859–76.
  4. Sockeye salmon identification - King County [Internet]. [cited 2021 Apr 23]. Available from: https://kingcounty.gov/services/environment/animals-and-plants/salmon-and-trout/identification/sockeye.aspx
  5. Fisheries N. Sockeye Salmon | NOAA Fisheries [Internet]. NOAA. 2021 [cited 2021 Apr 23]. Available from: https://www.fisheries.noaa.gov/species/sockeye-salmon
  6. Eliason EJ, Clark TD, Hague MJ, Hanson LM, Gallagher ZS, Jeffries KM, et al. Differences in Thermal Tolerance Among Sockeye Salmon Populations. Science. 2011 Apr 1;332(6025):109–12.
  7. 5 Ways People Are Helping Wild Salmon [Internet]. [cited 2021 May 7]. Available from: https://www.nature.org/en-us/about-us/where-we-work/united-states/alaska/stories-in-alaska/alaska-five-ways-we-help-salmon/

Image Credit

Two sockeye salmon swimming in different directions” by Milton Love, Marine Science Institute, University of California, Santa Barbara, CA 93106. Obtained from Wikipedia https://en.wikipedia.org/wiki/Sockeye_salmon#/media/File:Sockeye_salmon_swimming_right.jpg.This photograph has been released into the public domain by its author, Milton Love and is available under the Creative Commons CC0 License.

"Fraser River, Canada, near the "West Fraser Historic Trail" (north of Lillooet)” by China Crisis. Obtained from Wikipedia. This photograph is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported, 2.5 Generic, 2.0 Generic and 1.0 Generic license.

 

 

Can the Fire Salamander Handle the Heat?

Author: Jeremy Schloss

Climate change talks often discuss environmental issues such as increasing natural disaster intensity and coral reef bleaching, but human-driven climate change can affect species in very subtle ways too. With rising temperatures, new dangerous diseases are appearing and wreaking havoc. Chytridiomycosis (commonly shortened to chytrid) is a fungal infection that has been destroying amphibian populations around the world for the past few decades. Humans have aided its spread through international trade and the pet trade (1). It requires water and moisture to spread and survive. This infection results in the spread of fungal spores across the skin of amphibians, a perfect moist home to grow. Since many amphibians breathe through their skin, the spread of the spores results in the suffocation and death of the animal (2). 

One such skin-breathing amphibian is Salamandra salamandra, the Fire Salamander. Native to Europe, this salamander is identified by its bright yellow splotches on the back, stomach, and sides of its otherwise black body. Some variants may have yellow or red, but the pattern is unique to the individual. Their diet is mostly made up of insects, worms, slugs, and occasionally other amphibians. The unassuming salamanders also pack a hidden punch, a toxin called samandarin, which it stores in glands around its body. This compound can cause convulsions, hypertension, and hyperventilations in other vertebrates and has even been theorized to be a method of keeping infections away (3). 

Rising temperatures can dramatically shift the ability of an animal to fight disease. All animals have a Thermal Neutral Zone, a range of temperature in which they function most optimally. Living outside of that range can affect how fast they digest, how much they need to eat, and even decrease the strength of the immune system. Salamanders are cold-blooded animals; they aren’t able to control their body temperature and instead rely on the environment for warmth and cooling. While salamanders might normally occupy warm areas, increasing temperatures force them to avoid heat and gather in the shade. Temperatures have also limited the space that is considered an escape from the heat, leading to larger gatherings in shade. This creates a dangerous space for disease spread. 

Like the salamander, chytrid has its own thermal neutral zone between 17-25°C and over 30°C can be lethal to the fungus (2). While global temperatures have risen, locally this can lead to an increase in water evaporation and cloud formation. This can decrease the daytime temperature while increasing nighttime temperatures, potentially keeping the fungus within its favorable temperature range. Luckily, salamanders have some adaptations that may allow them to fight the disease. While their favorable temperature range is 17-21°C, they can survive up to five days in temperatures well over 25°C (4). Their ability to occupy this higher temperature may be their greatest advantage against the disease. 

While there is not a solution to treating the fungal infection itself, we can still do a great deal to limit the spread and severity of the disease. Rigorous trade regulations can limit the spread of chytrid to uninfected areas. More carefully regulating the pet trade especially can reduce the risk of transporting infected animals. In general, making great efforts to reverse temperature increases and greenhouse gas emissions can reduce the spread of the disease in the wild and allow for salamanders to combat the disease through behavior. 

 

Photo Credit

Photograph of Salamandra salamandra- Credit: By Petar Milošević from Orle hill, Slovenia - Fire Salamander (Salamandra salamandra), CC BY-SA 4.0, https://commons.wikimedia.org/wiki/File:Fire_salamander_(Salamandra_Salamandra).jpg

Microscope photograph of chytrid infection- Credit: Public Domain, https://commons.wikimedia.org/wiki/File:Chytridiomycosis2.jpg


Citations

  1. Burrowes, P.A.; I.D.d. Riva (2017). "Unraveling the historical prevalence of the invasive chytrid fungus in the Bolivian Andes: implications in recent amphibian declines". Biological Invasions. 19 (6): 1781–1794.
  2. Whittaker, Kellie; Vredenburg, Vance. "An Overview of Chytridiomycosis". Amphibiaweb.
  3. Griffiths, R (1996). Newts and Salamanders of Europe. London: Academic Press.
  4. Beukema, W., Pasmans, F., Van Praet, S., Ferri‐Yáñez, F., Kelly, M., Laking, A., Erens, J., Speybroeck, J., Verheyen, K., Lens, L., Martel, A., & Auer, S. (2021). Microclimate limits thermal behaviour favourable to disease control in a nocturnal amphibian. Ecology Letters, 24(1), 27–37.

Can the King of the Jungle Take the Heat? How Climate Change is Impacting Male-to-Male Competition in African Lions

Authors: Sadie Grant, Olivia Weaver, Audrey Deutsch, Joshua Zupan

Lions are universal symbols of royalty, bravery and power, all thanks to the mane found on males. Unfortunately, research shows that the thickness and density of the lion’s mane may be negatively affected by rising temperatures. While a mane may seem like a flashy way of showing off to the ladies, it is actually a trait that helps stop males from fighting each over before they even start. Some studies have shown shown in some studies that females actually don’t care so much about how their partners look-- they care about how well 

they defend a territory (1). Instead, manes serve as a symbol to other males that an individual is healthy and strong, and therefore not worth fighting. One study found that male lions approach life-sized dolls with sparse or light-colored manes than dolls with thick, dark manes (2); they were most likely intimidated by the darker, fuller manes. 

A lion’s pride is made up of a couple of males that preside over a larger group of females, who hunt and raise their cubs together (3). These prides are susceptible to male takeovers and infanticide, where the alpha male will be attacked and killed by a foreign male, who then kills the present cubs as well (4). They do this because it makes all of the adult females ready to have new cubs. Kind of harsh, I know. This behavior shows how important it is for a male to appear dominant, and studies have shown that darker, thicker manes do indeed ward off potential attackers (2). 

The lion’s mane evolved when ancestral lions began living in groups (5). In the age of the Pleistocene (post dinosaurs), ancient lions developed their manes through sexual selection. You may be thinking, “how could manes evolve from sexual selection if lionesses don’t have a preference”? The answer is that sexual selection can be driven by competition between males, too! (2). According to a study in 2006, things as specific as the size of the mane indicates a male’s nutritional status, and environment, and the color of the mane can even reveal a male’s age and hormone levels; it’s a tell-tale sign of how a lion is doing and if they’re able to defend themselves or reproduce. (6). Pretty handy info for a rival male who might be trying to usurp another’s territory.  

 

The Effect of Climate Change on Mane Density and Color

Between us and our understanding of changing mane densities sits a complex network of both direct and indirect anthropogenic influences that cannot be overlooked when considering the threats that climate change pose over lions. Since temperature can impact a lion’s mane density and color, they may be in trouble because scientists predict that temperatures will rise by four degrees celsius in Africa in the coming years (7). How will the male lion react to the stifling heat? Some scientists speculate that the temperature increase may bring about major changes to how males combat one another for resources (such as food and females). Not all is lost however, because the lions of the Serengeti have a cousin that lives in a much hotter climate. And believe it or not, these cousins in Tsavo, a region of Kenya, have little to no manes at all (they’re bald!). But don’t let that fool you. In spite of their lack of hair, Tsavo lions are just as lucky with the ladies as lions with a full head of hair in the Serengeti are in terms of reproductive success (10). Therefore, it seems that what impacts mane density the most is temperature (6). The cooler the climate, the thicker the mane. This has been observed in many captive lions kept in varying climates around the world. What may in fact be the most damning to a lion’s fitness is their access to water (8) but that is still yet to be seen. 

 

Conclusion: 

While we know that darker, thicker manes increase body temperature and heat stress, it is hard to predict how they will be affected by climate change in the coming years. A hotter climate means there will be less access to watering holes and even further down the road, less vegetation that could provide shade (9). However, the loss of the mane might not mean doom for these charismatic cats: maneless lions exist too (and they aren’t just the ladies)! In the Tsavo region of Kenya, the climate is hot and dry, with little shade cover. The male lions in this region have ditched the mane in order to stay cool, and they don’t seem to be socially or reproductively affected (10). In fact, pride size, number of offspring and males per group seem about the same between maneless and maned populations. Additionally, manes might have disappeared for Tsavo lions because there are simply less lions there - after all, the “mane” function is as a social badge of health and maturity. With less lions to worry about, there is a decreased demand for a symbol to decrease fights. Overall, the potential loss of manes in male lions will be a sad result of climate change. Just imagine future generations looking at marble carvings and statues of lions that guard so many doors and gateways throughout civilizations, and wondering why those lions have manes, when lions in their time don’t. The bad news about all this is that manes are a result of health factors, so manelessness could mean a deteriorating environment. The good news is that manes don’t seem to affect reproductively ability, so their loss will just mean that lion societies will have to find a new way for males to show off.  While it can be difficult to tell how much climate change will affect the lion mane, more research on the influence of female choice over mane evolution could shed light on this issue, as well as more research into possible differences between males with and without manes. 

 

Acknowledgements:

Lion (Panthera leo) lying down in Namibia. Source: Wikipedia. Licensed under Creative Commons https://en.wikipedia.org/wiki/Lion#/media/File:Lion_waiting_in_Namibia.jpg

 Male East African lion with a scanty mane at Samburu National Reserve, Kenya. Source: Wikipedia. Licensed under Creative Commons https://en.wikipedia.org/wiki/Maneless_lion#/media/File:Lion_male_with_scanty_mane_at_Samburu_NR_2.jpg

 UMNews. “A Mane Is a Pain, but Worth It for Male Lions.” EurekAlert!, 22 Aug. 2002, https://www.eurekalert.org/pub_releases/2002-08/uom-ami081902.php.

 “Lion Mane Linked To Climate.” ScienceDaily, ScienceDaily, 14 Apr. 2006, https://www.sciencedaily.com/releases/2006/04/060414003130.htm.

 
Citations

  1.  P. M. West, The Lion’s Mane: Neither a Token of Royalty nor a Shield for Fighting, The Mane is a Signal of Quality to Mates and Rivals, but One That Comes with Consequences. American Scientist. 93, no. 3 226-235 (2005). 
  2. P. M. West, C. Packer, Sexual selection, temperature, and the lion’s mane. Science. 297, 1339-1343 (2002). https://science.sciencemag.org/content/297/5585/1339
  3.  K. G. Van Orsdol, J. P. Hanby, J. D. Bygott, Ecological Correlates of Lion Social Organization (Panthers, Leo). Journal of Zoology. 206, no. 1 97–112 (1985). https://doi.org/10.1111/j.1469-7998.1985.tb05639.x.
  4. C. Packer, A. E. Pusey, Male Takeovers and Female Reproductive Parameters: A Simulation of Oestrous Synchrony in Lions (Panthera leo). Animal Behaviour. 31, 334-340 (1983).  https://www.sciencedirect.com/science/article/pii/S0003347283800517
  5.  N. Yamaguci, Evolution of the mane and group-living in the lion (Panthera leo): A review.  Journal of Zoology. 263, 329 - 342 (2006). https://www.cambridge.org/core/journals/journal-of-zoology/article/evolution-of-the-mane-and-group-living-in-the-lion-panthera-leo-a-review/BD5A14EAA0CFAE71EE8E37F006B9733D
  6.  B. D. Patterson, R. W. Kays, S. M. Kasiki, V. M. Sebestyen, Developmental effects of climate on the lion’s mane (Panthera leo). Journal of Mammalogy. 87, 193-200 (2006). https://academic.oup.com/jmammal/article/87/2/193/866474
  7.  O. Serdeczny, “Climate Change Impacts in Sub-Saharan Africa: From Physical Changes to Their Social Repercussions.” Regional Environmental Change 17, 6, 1585-1600 (August 2017). https://link.springer.com/article/10.1007/s10113-015-0910-2
  8.  P. Trethowan, Getting to the core: Internal body temperatures help reveal theecological function and thermal implications of the lions’ mane. Ecology and Evolution. 253-262 (2017). https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.2556
  9.  G. G. Celesia, A. T. Peterson, Climate and Landscape Correlates of African Lion (Panthera Leo) Demography. African Journal of Ecology. 48, no. 1: 58–71 (2010).
  10.  R. Kays, B. D. Patterson, Mane variation in African lions and its social correlates. Canadian Journal of Zoology. 80, 471-478 (2002). https://www.nrcresearchpress.com/doi/abs/10.1139/z02-024#.XdCwOkVKjOR 

Climate Change is the Biggest Bully of the Ocean According to Hybrid Groupers

Author: Carolina Fulginiti

Key words: Homeostasis, Basal Metabolism, Hyperventilation, Anabolic Energy

A Changing Climate

Climate change started to emerge at the beginning of the industrial revolution. It has lately been creating a big negative impact on the oceans. This is because climate change created by human activities induces an increase of atmospheric CO2 that is being absorbed into the ocean at alarming rates. This is causing the oceans pH levels to decrease which in other words means the oceans are acidifying that is resulting in an increase in water temperature all over the world. To learn more information on ocean acidification and its impact on ocean life, refer to here. Warmer water temperatures is an issue worldwide but it is a bigger problem in tropical waters like the Indo-Pacific. This is because the organisms that live there are already living at the maximum temperature that their bodies can tolerate (1). Most of these organisms have adapted to these tropical waters making it their ideal water temperature. So any change in temperature can be extremely harmful to tropical organisms like Hybrid Groupers.

What is a Hybrid Grouper?

A Hybrid Grouper are two species of Grouper fish, the Tiger Grouper and the Giant Grouper (Mycteroperca tigris × Epinephelus lanceolatus), that have mated together to form the Hybrid Grouper population. These fishes are tropical water species that live in the Indo-Pacific. Juveniles spend most of their time on the coast while adults spend most of their time offshore, where they live depends on their size (2). This is because bigger Hybrid Groupers are capable of fighting off threats more easily than smaller Hybrid Groupers. Hybrid Groupers can be found at close proximity to rocky bottoms or coral reefs which are abundant in the Indo-Pacific (3). Larvae and Juveniles feed on plankton like Copepods and other zooplankton while adults feed on crustaceans and fish. This makes sense because they eat according to their size; smaller Hybrid Groupers eat smaller animals (plankton) and larger Hybrid Groupers eat larger animals. These fish are protogynous hermaphrodites which means they are females at birth and are able to switch sex to males (3). It is not known if Hybrid Groupers always change sex into males or if they only do it if there is a shortage of males for breeding. The ideal temperature for these fish to breed in is around 24ºC to 30ºC which is also their ideal temperature to live in (2). To learn more about these amazing fish, you can visit here.

Climate Change impacting Hybrid Groupers

Climate change is bringing more acidic water and warmer water temperatures to the Indo-Pacific where Hybrid Groupers live. Their ideal water temperature is between 24ºC and 30ºC (1) so increasing the water temperature from this range can kill them. In order for these fish to survive, they have to create physiological responses to deal with the stress of climate change. These fish deal with stress by creating a trade-off between using more energy for physiological traits that are needed in order for them to survive. The other traits that they use when temperatures are normal and are not needed for survival use up less energy so that more energy can be used to help them survive. These animal’s bodies have to respond quickly to the changing environment and allocate the energy efficiently so less harm is done. We are going to look at how one specific female Hybrid Grouper in the Indo-Pacific responds to climate change.

Feeding Behavior

This Hybrid Grouper is one of the many fish exposed to warmer water temperatures and an increase in water acidity. She responds to this type of stress by inducing hyperventilation. Hyperventilation is a response that is common in fish when they are exposed to environments with high amounts of CO2. This is because it causes a decrease in the amount of CO2 in the blood (4). She also responds to climate change stress by inducing protein mobilization where protein is used in the muscle and liver tissues as anabolic energy to support basal metabolism (1). Anabolic energy is the process of synthesizing complex molecules from simpler ones and this case is the building of proteins from amino acids (5). To have a refresher about metabolism and how it works in the body, you can go here. Basal metabolic rate is the minimum amount of energy needed to fuel basic functions. So she uses proteins to allocate energy into increasing their basal metabolism and ventilation rate in order to stay alive. This means that the energy that is used to keep herself alive is energy that is taken from other physiological functions like foraging for food. 

Growth Rate

Another way this fish responds to climate change is that she tends to be smaller when exposed to stress. This is because she is following the same patterns as they did with feeding behavior where she spends less energy on growth rate and more energy trying to maintain homeostasis (1). Where homeostasis is the state of equilibrium inside an organism’s body. Stressors like climate change deviate her homeostatic conditions and she is doing everything possible to try to maintain homeostasis. As I mentioned before, her feeding intake decreased because less energy is being used for food foraging so she will grow at a slower rate (1). This shows that growth rates are not just impacted by temperature but also by feeding behavior, location, type of species, stage maturity, and other physiological traits.

Glycogen and Ammonia Production

The last way this fish responds to climate change stress is by preserving and sacrificing glycogen to support her basal metabolism. Glycogen is one of the main sources of energy for Hybrid Groupers. Preserving glycogen and using other molecules like proteins and lipids to produce glucose, that is used as energy, to support basic metabolic processes (6). When this fish is exposed to an acidic environment, she sacrifices glycogen in both her muscle and liver to use as energy. This is because more energy needs to be used in acidic environments for survival (1). Using more glycogen as energy is also the case for this fish to excrete ammonia production. Waterborne ammonia that includes NH4+ and NH3 are toxic to fish and need to be excreted from their bodies (3). Increase in water acidity is causing ammonia excretion to be done more ineffieciently that can potentially kill this fish if there is a significant build up. 

Hybrid Groupers cannot survive on their own!

As you can see, there are a lot of different changes and responses that are going on in this Hybrid Grouper when she is exposed to a stressful environment. There are likely more responses going on in her body at this time but I only focused on three of them. These responses are complicated ways that these fish expend energy to try to stay alive. I want to note that this is not ideal for them and many fish don’t survive because of the imbalance of energy expenditure. Also, Hybrid Groupers are just one of the many species of Groupers that live in our oceans and they can either respond similarly to this fish or drastically different. As a next step, more research experiments can be done with Hybrid Groupers, like the fish mentioned above, and other species of Groupers together to be able to compare and contrast the results of each species in one area. More research on Groupers available to the public is essential for creating awareness of how dangerous climate change can be for tropical marine life. Once more information is available to the public, then conservation efforts can start to try to save these fishes from being exposed to stressful environments that can potentially kill them.


Citations

Photo Credits:

  1. Sea Surface pH: Plumbago, CC BY-SA 3.0 , via Wikimedia Commons
  2. Hybrid Grouper: Kerapu Online, CC BY-NC-SA 2.0, no changes have been made: https://www.flickr.com/photos/kerapuonline/15692244232/in/photostream/

Literature Cited

  1. Y. A. Thalib, R. S. Razali, S. Mohamad, R. Zainuddin, S. Rahmah, M. A. Ghaffar, H. J. Liew, Environmental changes affecting physiological responses and growth of hybrid grouper – the interactive impact of low ph and temperature. Environmental Pollution, 271, 116375 (2021).
  2. J. W. Jr. Tucker, Species profile grouper aquaculture. Southern Regional Grouper Aquaculture, 721, 1-11 (1999).
  3. L. T. Seng, Grouper culture. Tropical Mariculture, 423-448 (1998).
  4. R. Ern, AJ. Esbaugh, Hyperventilation and blood acid-base balance in hypercapnia exposed red drum (Sciaenops ocellatus). J Comp Physiol B., 186(4), 447-60 (2016)
  5. S. Malmquist, K. Prescott, “Energy and Metabolism” in Human Biology, License: Creative Commons Attribution NonCommercial
  6. Y. Tseng, P. Hwang, Some insights into energy metabolism for osmoregulation in fish. Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, 148, 419-429 (2008).

Climate Change Isn't so Foxy

Authors: Sarah Albright, Erin Knopp-Sargoni, Leah Cummings

The arctic is a tough place to live with long, dark winters where snow covers the ground for six months, and short, mild summers. It is a landscape dominated by glaciers and permafrost year-round. Yet amidst difficult conditions, life manages to thrive here. The arctic fox is one of the few species to call the arctic home (4). With drastic changes in temperatures and the “arctic night”, a period of time where the sun does not rise for sometimes several months at a time, the arctic fox has had to come up with ways of dealing with these conditions. The cold icy tundra may not seem like a suitable place for many mammals to live, however the arctic fox inhabits arctic tundra around the globe. While the arctic tundra might seem like a harsh and robust environment, it is surprisingly fragile and threatened by climate change. With dwindling arctic habitat, the life of the arctic fox will become increasingly difficult, especially as climate change progresses.

Join us on a journey observing a young female fox who navigates through the icy arctic tundra. Here she’s presented with multiple obstacles throughout the year ranging from predators, lack of food, and diminishing habitat.

The icy breeze runs through her fur and down along her back as she makes her way through the rocky terrain. Her fur is very dense for having such a small body, but this is one of the only ways she can keep warm in the arctic tundra. Her fur is white as snow and helps her to blend in with the winter snow and decreases her risk of being eaten by golden eagles and polar bears. With increasing global temperatures, there isn’t enough snow on the ground to keep her camouflaged. Now, this young fox is left to find the largest snowpacks to hide her away from predators.

Her coat will change in the summer months to a darker brown that helps her blend in with the melting landscape. However, if the ice melts too soon, she’s at a greater risk of being exposed to predators. Increases in temperatures cause winter to end sooner than previous years. In the past decade, the arctic has experienced its highest temperatures to date (5). These increased warm pulses decrease the snowpack and make winter life tougher. Her physiological adaptations to arctic winter are less advantageous with a landscape melting into summer. These adaptations include metabolism, dense fur, increased fat storage and insulation (3). Unlike humans who have the weather channel, arctic foxes don’t have the tools to predict how warm and dry their winter may get. They are left to roll with the changes in their environment, in hopes that they can adapt. 

The arctic fox searches for a nice lemming to feed herself.  She is a top predator in the arctic tundra and depends on small mammals like the lemming, seabirds, and the occasional seal pup (1). When there’s plenty of food to go around she will hide some of her prizes in various rocky fields across the mountain. Arctic foxes have been known to do hide their abundant prey catches in the winter seasons, possibly to prevent starvation when prey sources are depleted (3). When prey numbers begin to decrease in winter, her body knows to start storing more fat to endure the coming weeks. This body change allows her to sustain herself even when she cannot find a meal for several days or even weeks. Due to the foxes’small size, fur depth in relation to body size cannot be too big. Having too much fur or insulation for such a small body decreases effective movement. In contrast to larger mammals that grow less fur and smaller mammals that have a thinner insulation layer and must hide under the snow cover, arctic foxes have very dense fur and thick insulation layers (4). Arctic foxes are the only mammals that have this unique insulation to fur density index.

A red fox calls in the distance in search of its mate. The arctic fox looks up and studies the landscape. These two species of foxes have become neighbors in the last several years. The red fox’s boreal habitat, which consists of conifer forests, wetlands and marshes, has extended up into the arctic. And these foxes don’t exactly have a friendly neighborhood alliance. Red foxes are top predators in boreal forests and can quickly outcompete arctic foxes in inland tundra if their ranges overlap too much. The red fox is a faster, stronger hunter that proves to be tough competition for prey (1). In the arctic, where prey can often be scarce, this competition could prove to be detrimental to the arctic fox’s success.

The arctic fox looks towards the coast and hears the crashing waves. She sees the faint outline of an island. There are some arctic foxes that inhabit these coastal tundra islands. Their seclusion provides a safe refuge from competition with the red fox. They are typically accessible by sea ice ridges that connect them to the mainland (2). By having a larger landscape to move through, the arctic foxes are able to mate with individuals from different areas. Mating with other foxes from various locations will increase the diversity amongst the species. A larger genetic diversity decreases the risk of interbreeding, disease, and natural disasters that could potentially harm population dynamics. With climate change, these ice ridges are getting smaller and even disappearing altogether. If the ice ridges melt too far, the arctic fox populations are at a greater risk for genetic isolation. This could lead to an increased risk of extinction. The arctic fox looks away and begins to trot off into the night. She has experienced another challenging day in the arctic.

What happens when you are an expert at living in the arctic tundra, but warmer temperatures are steadily changing the environment around you? As we’ve seen, there are hardships this female fox will face throughout her life, and as climate change accelerates, these will get even more challenging. Increases in global temperatures and seasonal variation clearly alters the arctic landscape which greatly impacts the future of the arctic fox. Like most climate-endangered species, it is adapt or die for the fox. Luckily, this species is not totally in the red zone yet. With more research that focuses on determining how arctic foxes respond to changes in their environment, we can create conservation and management protocol that can better protect this fragile species and its habitat. This all starts with improving our current knowledge of the physiology of the arctic fox and how 

On a more personal level, educating the general public on the realities of climate change and how it impacts fragile ecosystems, such as the arctic tundra and its species, could motivate more grassroots movements that influence policy changes. By changing the mindsets of populations, we can more effectively work towards a society geared towards climate health. It is clear that the arctic fox is crying out for help and it is not alone in its plead for a right to live in its natural habitat. The changes that have altered their habitat are not completely detrimental to their future. But it is up to us to make sure that we listen so that we can help heal and not hurt this beautiful species.


Citations

 

  1. Fuglei, E., Anker, R. (2008). Global warming and effects on the arctic fox. Science Progress, 91(2), 175-191.

 

  1. Mellows, A., Barnett, R., Dalén, L., Sandoval-Castellanos, E., Linderholm, A., McGovern, T., & Larson, G.(2012). The impact of past climate change on genetic variation and population connectivity in the icelandic arctic fox. Proceedings: Biological Sciences, 279(1747), 4568-4573.

 

  1. Prestrud, P., Nilssen, K. (1995). Growth, size, and sexual dimorphism in arctic foxes. Journal of Mammalogy, 76(2), 522-530.

 

  1. Prestrud, P. (1990). Adaptations by the arctic fox (Alopex lagopus) to the polar winter. Arctic Institute of North America. 44(2), 132-138.

 

  1. Walsh, J., Overland, J., Groisman, P., & Rudolf, B. (2011). Ongoing Climate Change in the

          Arctic. Ambio, 40, 6-16.

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