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Save our Beautiful Pollinators!

Author: Lance Luong

Introduction

When looking at a butterfly, there’s so much that they went through during their short lives. Butterflies are beautiful creatures that make our world much more colourful with their beautiful wings and ability to help pollinate and keep our plants healthy. We are losing populations of butterflies for a multitude of reasons. Butterflies are being affected by climate change, thus driving them away from their homes. Their homes are being much more cramped and their populations are declining. They are competing for a limited amount of land and it’s causing a strain on other butterfly populations. Butterflies are having difficulty flying and their lives are drastically changing because of human interaction with our environment. Today, we will be focusing on the Pararge aegeria, also known as the wood speckled butterfly or the speckled wood butterfly. We need to know that butterflies need our help to preserve their habitats and combat against climate change that negatively impacts them and us. But first, you need to know what they look like!

 

About the Pararge Aegeria Butterfly!

The Pararge aegeria, also part of the Nymphalidae family, or more commonly known as the Speckled Wood Butterfly is a common butterfly species with a wide range in Europe and Northern Africa and are often studied due to their large populations and changes in the past years. These butterflies favour staying in the shade due to their speckled brown, cream, yellow, black, and warm colour tones. They are not endangered, but they are a very important butterfly species for many scientific studies. They, like many other butterflies, have short lifespans from the egg to the adult butterflies. This allows these butterflies to go through many evolutionary changes quickly and allows us to study these changes. With a short span, the speckled wood butterfly has gone through many changes that led them to inhabiting a wide variety of areas. Climate change along with environmental changes have affected them greatly. 

 

What effects does human change have on butterflies?

When new buildings and infrastructures are built, habitats are going to change. Planting more trees can also affect the habitat in ways that drive away butterflies. With environments changing and temperatures rising, butterflies are migrating to habitats less suited for them (2). For example in Madeira, another species of butterfly called Pararge xiphia used to live in areas that were lower in latitude in warmer climates, but the people there started to build homes, buildings, and plant more forests of eucalyptus and pine, altering the P. xiphia’s homes (3). This pushed them to live in new areas and this allowed other butterflies to rapidly colonise their previous home and thrive heavily. What was also believed to be the decline of the P. xiphia, was the Pararge aegeria’s or the speckled wood butterfly’s success on the Island of Madeira because their population was increasing heavily while P. xiphia populations started to drop (3).

The speckled wood butterfly is rapidly expanding throughout large areas, ranging from the western Palaearctic, the UK, central Scandinavia, and North Africa (1). Their large range is thought to be from their evolution of wings and that allowed longer flight and this allowed them to be able to colonize many different areas (1). These butterflies are constantly changing from causes of temperature variations in latitudes and humans altering the butterflies’ homes. There have also been multiple studies that have shown that butterflies are more prone to increased generations from climate warming (3). Speckled wood butterfly populations are expanding in higher latitudes and causing morphological changes in their wing size and shape (1). These changes were also related to increased reproduction as well. With their wing changes and ability to reproduce more, this often led the wood speckled butterfly to colonise more areas

As the speckled wood butterflies colonised more areas and humans altered environments, these butterflies have also been affected in their flight and bodily functions as well. Butterflies’ bodies are sensitive to temperature changes and this would affect their metabolisms and how their bodies work (5). An example of this would be in Northern Europe as more land was dedicated to agriculture, the speckled wood butterfly started to undergo changes while the latitudinal changes were affecting the temperature and amount of sunlight these butterflies were experiencing (5). Their energy needed to fly started to change and they needed to work harder to keep their body at a certain temperature.

 

How can we help butterflies?

As butterflies are losing their habitats, we need to help them regain the resources they need. In areas that are more urban, we can help butterflies by letting our gardens grow a variety of trees and plants. There are also many different reserves dedicated to butterflies where experts are able to study these butterflies to understand them more. We can help support them by donating, bringing attention to them, and even volunteering! Research is also helpful when it comes to helping certain butterflies. For example, growing milkweed is beneficial to providing monarch butterflies with food to help sustain their migration to Mexico.

There are plenty of resources to find butterfly needs. It’s important to follow butterfly numbers and look at conservation statuses. The speckled wood butterfly is not in any immediate danger of extinction, but butterflies are highly susceptible to any climate change due to temperature and habitat destruction. Monarch butterflies are in danger, so there are plenty of resources to create your garden into a butterfly station to aid them. You’ll find the monarch’s status, their threats, their favourite food and how to work together to conserve these beautiful pollinators. Pollination is important for plant ecosystems and there are many agencies sharing the importance of flowers that butterflies tend to go to and it's important to know what type of butterflies you might be able to find in your area! So please help our butterflies, especially our monarch butterflies and grow some milkweed in your garden! Here is a beautiful picture that’ll hopefully convince you to get some milkweed and grow them near your home!

 


Citations

1. Taylor-Cox, E. D., Macgregor, C. J., Corthine, A., Hill, J. K., Hodgson, J. A., & Saccheri, I. (2020). Wing morphological responses to latitude and colonisation in a range expanding butterfly. PeerJ.

2. Hill, J. K., Thomas, C. D., & Blakeley, D. S. (2020). Evolution of Flight Morphology in a Butterfly That Has Recently Expanded Its Geographic Range. Springer, 121(2 (1999)), 165–170.

3. Bland, E. W., & Lace, L. A. (n.d.). On Madeira, the success of the speckled wood butterfy (Pararge aegeria) has coincided with declining populations of the Madeiran speckled wood (Pararge xiphia): Is the colonist to blame? Springer, 24(2).

4. Altermatt, F. (2010). Climatic Warming Increases Voltinism In European Butterflies and Moths. Proceedings of the Royal Society B: Biological Sciences, 277, 1139–1298.

5. Dyck, H. V., & Holveck, M.-J. (n.d.). Ecotypic differentiation matters for latitudinal variation in energy metabolism and flight performance in a butterfly under climate change.

 

Photo Credit

Photograph of a Male Pararge Aegeria, Credit: by Charles J Sharp. Public Domain, https://commons.wikimedia.org/wiki/File:Speckled_wood_(Pararge_aegeria_aegeria)_m ale.jpg

 

Country Bug in the Big City: The Future of Honey Bees

Author: Casey Martin

A Vital Insect

Did you know that 30% of all global crops are pollinated by honey bees? These little insects have a big responsibility, and with rising temperatures and expanding cities, it’s important to be certain that they’re equipped to survive a changing world. Fortunately, honey bees don’t work alone. They live in colonies headed by a queen, who lays all the eggs for the colony, and populated by female workers and male drones. To learn more about the differences between these three types of bees, check out this article! Worker bees have lots of responsibilities, including protecting the brood of the queen’s eggs, building and maintaining the hive where they live, and foraging outside the hive for pollen, nectar, and water. One of their most important jobs is colony thermoregulation, keeping the hive at a constant temperature so that the eggs can properly develop, and honey bees have learned to work together in fascinating ways to achieve this (1). The ability to cooperate is so vital to their survival that honey bees are often referred to as a superorganism. This means that, when considering honey bee survival, we have to look at the activity of the whole colony, as well as the individual bees.

 

Bee Sauna

A honey bee regulates its own temperature much like we do, shivering when they’re cold and using evaporative cooling akin to sweating when they’re hot. But worker bees are also responsible for keeping the whole colony at a comfortable temperature, which is much too big of a job for a single bee. To manage this, workers swarm together and start shivering to create heat. If it gets too warm, some bees will leave the swarm to go forage. If it’s still too hot, they will spread water around their nest and start fanning with their wings, like natural air conditioning. If it’s very cold, keeping the whole colony at a comfortable temperature will require too much effort, so the workers will focus on keeping the eggs warm first, and not worry so much about the storage areas of the colony (2). These various strategies mean that honey bees are able to adjust to a wide range of temperatures from 5C to over 45C (3).

 

Hot Bees are Happy Bees

While they can survive at many different temperatures, honey bees actually find it easier to operate at higher temperatures. Their metabolic rate, the amount of energy it takes for them to do an activity, decreases at temperatures above 38C (3). In addition, since it’s so warm out already, fewer bees are delegated to keeping the colony warm, meaning that more bees are out and about looking for food and water. The colony needs lots of water when it’s hot to keep cool, so many of these foragers will be gathering water. However, since bees also don’t need to eat as much in the heat, they’re able to build up their food storages during warm periods and be overall more efficient (4). If that wasn’t good enough, honey bees also get a boost to their immune system when it’s hot. This was shown in a study where bees were exposed to a simulated heat wave which resulted in lower levels of viral wing deformities (5). Essentially, while rising global temperatures are a big problem for a lot of reasons, honey bees seem like they’ll be ready to handle a hotter world and may even benefit from it. But climate change isn’t the only potential threat to honey bee habitats….

 

City Living

The rise of cities affects honey bee habitats in lots of ways, and one of the most important is that daily temperatures in urban settings are pretty different from rural settings. While cities usually don’t get hotter than their nearby rural neighbors, they do hold onto that heat better. This is because of the lack of plants providing shade, buildings and structures preventing wind from cooling it down, and the high concentration of people doing human activities, all of which generate enough heat that cities don’t get as cold as rural places (6). This means that city bees don’t have to adjust to widely varying temperatures in the same way as rural bees and spend less time in cold temperatures. Studies have shown that honey bees are able to adjust to the temperatures they live in, and will actually prefer the temperature of the environment they are used to. While a city bee is probably going to be more susceptible to the cold, since they spend less time in cold temperatures, they may also become better suited for living in a constantly warm environment (7). So along with heat making work easier for honey bees, urban environments increase the time the bees spend in the heat, meaning city bees are operating at peak performance more of the time. This leads to urban bees having more efficient colonies than their rural neighbors (8).

Of course, urbanization has other effects that we need to take into consideration. With increasingly dense cities, we see a greater risk of infection among honey bees. The spread of pathogens is exacerbated by the close quarters of different colonies, limited food supply, and the increased foraging activity caused by higher temperatures. These factors lead to a higher risk of disease transmission between colonies in cities (9). So, while the increase in daily temperature associated with cities leads to higher immunity in bees, the urban environment means that it may be easy for diseases to spread regardless.

Another factor of concern is food availability and quality, since lots of cities contain non-native plants and limited green spaces where bees can forage. However, since bees are global pollinators, they can forage from lots of different types of plants, and urban bee populations do show increased amounts and variety of foraged pollen (8). So, while food availability must be considered when thinking about the future of bees in cities, and the type of food available can have other effects on colony health, overall honey bees do a pretty good job of finding food for themselves in cities.

 

Looking Forward

So, what does this all mean for our friend the bee? Well, the truth is that only time will tell how climate change and growing city landscapes will change the bee’s nature. We have some inkling of what’s going on, thanks to some folks who really, really like bugs, but there’s still lots to learn. We know that honey bees do well in the heat, so they’ll be okay with rising global temperatures and the higher temperatures in cities, but there’s also some conflict about whether they’ll get a boost to their immune system (5), or if they’ll be more likely to spread diseases to each other in an urban environment (9). There are also concerns about food availability and quality in cities that deserve consideration and further study. Moving forward, we need to make sure the cities we build are suitable habitats by providing green spaces with a variety of food sources. Though honey bees are equipped to handle some of the human-caused changes to the Earth, thanks to their adaptability, teamwork, and ability to allocate colony resources differently in different situations, they are still a vital and vulnerable species that must be protected. Honey bees provide a lot of things we may take for granted, but their survival is not guaranteed, and we must ensure that the world we build is one that honey bees can live in.

 

Key words: urbanization, thermoregulation, superorganism, apis mellifera


Citations

References

  1. Featured Creatures: Honey Bee. August 2013. Entomology and Nematology Department: University of Florida; [December 2017, April 2021].http://entnemdept.ufl.edu/creatures/MISC/BEES/euro_honey_bee.htm
  2. Stabentheiner A, Kovac H, Mandl, M, Käfer H. 2021. Coping with the cold and fighting the heat: thermal homeostasis of a superorganism, the honeybee colony. Journal of Comparative Physiology.
  3. Free JB, Spencerbooth Y. 1958. Observations on the temperature regulation and food consumption of honeybees (Apis mellifera). Journal of Experimental Biology. Volume 35 (Issue 4).
  4. Harrison JF, Fewell JH. 2002. Environmental and genetic influences on flight metabolic rate in the honey bee, Apis mellifera. Comparative Biochemistry and Physiology A- Molecular and Integrative Physiology. Volume 133 (Issue 2).
  5. Bordier C, Dechatre H, Suchail S, et al. 2017. Colony adaptive response to simulated heat waves on consequences at the individual level in honeybees (Apis mellifera). Scientific Reports. Volume 7.
  6. Sanchez-Echeverria K, Castellanos I, Mendoza-Cuenca L, et al. 2019. Reduced thermal variability in cities and its impact on honey bee thermal tolerance. PeerJ. Volume 7.
  7. Goller F, Esch H. 1990. Muscle potentials and temperature-acclimation and acclimatization in flight muscles of workers and drones of apis-mellifera. Journal of Thermal Biology. Volume 15 (Issue 3-4).
  8. Samuelson AE, Gill RJ, Leadbeater E. 2020. Urbanisation is associated with reduce Nosema sp infection, higher colony strength and higher richness of foraged pollen in honeybees. Apidologie. Volume 51 (Issue 5).
  9. Youngsteadt E, Appler RH, Lopez-Uribe MM, et al. 2015. Urbanization increases pathogen pressure on feral and managed honey bees. PLOS One. Volume 10 (Issue 11).

Photo Credit

Open access photos taken from Wikipedia

Photograph of foraging worker honey bee- Credit: I, Luc Viatour, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=856221

Thermal model of Atlanta, Georgia- Credit: Our World In Data - https://ourworldindata.org/grapher/urbanization-last-500-years, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=86956576

Let the Sun Shine Down: Hermatypic Corals' Newest Threat

Author: Verio Panelli

Keywords: turbidity, dredging, bleaching

Whether it be the bleaching events due to changing ocean temperatures or increasing ocean acidification, everyone has heard of a myriad of different threats that coral face. But did you know that many of these threats are actually more directed at their symbiotic relationship with zooxanthellae, a microalgae that lives inside coral colonies? Zooxanthellae are essential for providing reef building corals with the nutrients they need to grow their skeletons to the large size of their colony. As an algae, they get all their nutrients from photosynthesis and as such, light is extremely important to them and thus, reef building corals. But something is threatening this important interaction in the modern world, turbidity (a lack of clarity in water, usually due to sediments) in the shallow ocean. While we understand turbidity as an issue for standing water such as lakes, the threat can actually persist in the ocean, especially off the coasts. Though there can be turbidity from algal blooms caused by runoff, it is most often that the cause of turbidity in the ocean is dredging, the act of removing sediments from the bottom of the sea floor for smoother bottoms for coastal construction. This has become increasingly used in coastal cities to establish ports, military bases, and other common things seen in the urbanized coastal town. This removal can often cause a lot of sediment to be stirred up which blocks light from getting down to the coral. Yet despite warnings of the risk this posed to coral species dating back to the 70s (1), it still is a common practice, even in areas close to major coral reef systems such as Australia.  This is especially an issue for more sensitive corals like Pocillopora damicornis, a branching coral that is very vulnerable to light removal throughout its coral skeleton but especially in the tissues between the polyps (known as the coenosarc tissues), where the lack of light can cause the zooxanthellae to stop producing oxygen which can draw it to nearly suffocating levels after just around 10 minutes (2). This issue becomes more apparent for this species as the range of this species is mostly seen in the Indo-Pacific, especially in areas off the coast of Africa and Australia, areas where dredging occurs frequently. Additionally, the form of a branching coral inherently sets different levels to which the skeleton is exposed to light which makes removing light from the areas that are supposed to be most exposed to light can drastically alter the productivity of the colony. 

Yet with all these clear issues that turbidity in the ocean poses upon corals, why have you not heard anything more clear about it? Well, as recent research has surmised, it seems that while turbidity has negative effects on zooxanthellae within corals, some species are actually able to find a way around this issue. Surprisingly, some coral species are able to continue growing even when they are almost entirely lacking light and have bleached (3). Basically, it seems the science is inconsistent as one species is threatened significantly by the increased turbidity in the water but other species seem fine. The fact that corals can be bleached (meaning they have lost a great portion of their zooxanthellae) and still have the resources to grow implies that either the coral had some sort of nutrient storage system or is able to regenerate some of the lost zooxanthellae. But how could this be the case for some species but not others? The answer of course, lies in adaption and unique zooxanthellae for different species of coral. 

Zooxanthellae, like all other organisms, are divided into different species who are adapted to different environments and conditions. But even within similar conditions (such as the same coastline) there may be a couple of different clades (groups of species). In one study, a group of scientists’ tested the bleaching resistance of P. damicornis and Turbinaria reniformis mainly in the context of increasing temperatures. It was found that when the environment changed, P. damicornis lost zooxanthellae at a much faster rate than T. reniformis, even though P. damicornis had much more zooxanthellae within their tissues than T. reniformis at the beginning of the study (4). The reason? Despite the relatively small differences in location (sometimes when they lived in the same reef systems), these species of coral had two different clade groups that they used for zooxanthellae. Clearly, T. reniformis’ clades of zooxanthellae were much more temperature resistant than those of P. damicornis. The authors even found it was likely that this clade had been more exposed to changing conditions that would normally cause bleaching events and it had built up some resistance. 

While this study was mainly revolving around temperature changes, it makes sense that there would be a similar relationship between turbidity resistance and clade of zooxanthellae. While the study may have suggested a trend for adaptable zooxanthellae, it is not exactly ideal to hope the zooxanthellae will just adapt with not assistance. If such was the case there would likely be at least a bit more resistance in P. damicornis as the species has likely experienced a great amount of turbidity related stress already and is still significantly threatened by light’s removal. However, seeing as how advanced our understanding of manipulating microorganisms’ structures genetically, there may be a future in helping P. damicornis and other sensitive corals like it to adapt more turbidity resistant zooxanthellae. While it may be hard to individually impact this issue for good like it is for many other climate change issues, the fact there is a way for the corals to adapt to the changes to the environment should at least help provide a small light in the darkness.


Citations

1.  R. E. Dodge J. R. Vaisnys. Coral populations and growth patterns: responses to sedimentation and turbidity associated with dredging. Journal of Marine Research 35.4, 715-730 (1977). https://nsuworks.nova.edu/cgi/viewcontent.cgi?article=1046&context=occ_facarticles/ 

2.  K. E. Ulstrup P. J. Ralph A. W. D. Larkum M. Kuhl. Intra-colonial variability in light acclimation of zooxanthellae in coral tissues of Pocillopora damicornis. Marine Biology. 149.6, 1325-1335 (2006). https://link.springer.com/article/10.1007/s00227-006-0286-4 

3. R. Jones N. Giofre H. M. Luter T. L. Neoh R. Fisher A. Duckworth. Response of corals to chronic turbidity. Sci. Rep. 10, 4762 (2020). https://www.nature.com/articles/s41598-020-61712-w.pdf 

4. K. E. Ulstrup R. Berkelmans P. J. Ralph M. J. H. van Oppen. Variation in bleaching sensitivity of two coral species across a latitudinal gradient on the Great Barrier Reef: the role of zooxanthellae. Marine Ecology Progress Series. 314, 135-148 (2006). https://www.int-res.com/articles/meps2006/314/m314p135.pdf

Image citation:

Intro Image: An image of Pocillopora damicornis off the coast of Maldives. Photo taken by Ahmed Abdul Rahman on August 7, 2014, CC BY-SA 4.0. Sourced from https://en.wikipedia.org/wiki/Pocillopora_damicornis#/media/File:Pocillopora_damicornis_Landaagiraavaru.JPG.

Main Image: Stylized drawing of dredging done by Pearson Scott Foresman, Public Domain. Sourced from https://en.wikipedia.org/wiki/Dredging#/media/File:Dredge_(PSF).png. The image was uploaded 8 June 2009.

Too Cold for Comfort: How Climate Change is Affecting the Monarch Butterfly

Author: Isabella Cohen

Key Words: Monarch Butterfly, Climate Change, Migration, Temperature

Monarch butterflies (Danaus plexippus), are one of the most familiar insects native to the North American continent. Monarch butterflies are recognized as migratory insects because they travel great lengths depending on seasonality and temperature. Their migratory cycle starts in late summer as temperatures cool from southern Canada and across the United States to central Mexico where they stay over winter, and begin migrating northward when starts warming up during spring. Monarchs can be easily identified due to their unique wing pattern and orange color, a trait derived as a defense mechanism used to confuse predators for a poisonous insect (6). Butterfly wingspan can reach up to four inches, with males usually slightly larger than females. Females are oviparous, which means they lay eggs outside of their bodies. Monarchs love laying eggs on milkweed plants, which can be easily planted in your garden if you would like to attract these beauties. Monarch caterpillars only consume milkweed while adults mainly feed on plant nectar (5).

Caterpillars undergo a process called metamorphosis and pupate to transition from larvae to adulthood. During this process, the caterpillar will connect itself to a flat surface and form a chrysalis around itself while it undergoes the transition from a caterpillar to an adult butterfly (1).

An Unbearable Winter Break

Climate change has affected the physiology of the monarch butterfly in numerous ways. Due to the greenhouse gas effect trapping the sun’s heat in the earth’s atmosphere, summers are becoming much hotter and winters are becoming wetter and colder (3). Recently, monarch death rates have increased during overwintering (staying in one place over the winter) events in Mexico (2). A recent study suggests that winters have shifted towards conditions lethal to butterflies staying over for the winter in recent decades. Overwintering animals tend to nest or hibernate at a singular location when temperatures become warmer once a year. It has also started raining more in the area of Mexico where the butterflies migrate to. Combined with freezing temperatures, this area may become too cold for the butterflies to withstand (2). Monarchs are ectothermic, meaning they are able to warm and cool themselves based on outside temperatures and are sensitive to slight temperature changes (6). Dropping temperatures at their native overwintering site may greatly reduce butterfly populations (2).

In a 2019 study, it was found that monarch butterflies contain a hormone-induced “timer” that contributes to overwintering survival. The authors determined the components of an environmentally controlled, internal timer controlling the butterfly migration. This “timer” is triggered in accordance with permissive environmental conditions, usually when seasons turn cold (4). The punctuality of this hormone-induced timer may be altered due to shifting temperatures. Alterations in the monarch’s internal mechanisms may delay key life-history events, such as migrations, and alter entire ecosystems that rely on these insects (4).

Running Low on Fuel

A study investigating the metabolism of monarchs born and raised under temperatures similar to fall and summer in the United States and Canada found that butterflies born under autumn-like conditions showed lower post-flight metabolic rates, greater flight efficiency relative to monarchs reared under summer-like conditions, meaning that the autumn born monarchs had to spend less energy to fly. Because of climate change-induced temperature shifts, seasonality is becoming hard to predict and different from previous years. Summer-born monarchs expressed more power during flight than autumn-born monarchs, suggesting that they used more energy over time than monarchs born under autumn-like conditions (3). With higher temperatures becoming the norm, many butterflies may experience a slower metabolism while they are born in fall and experience summer-like temperatures.

What can we do?

Monarch butterflies contribute to our society by pollinating our crops and flowers. Without pollinators like them, we put our food supply and sustainability at risk. Green practices such as reducing fuel use, pollution, and other methods to reduce temperature fluctuations are necessary. Further research on the bodily functions of monarch butterflies is also necessary in order to understand how they respond to the external environment and what we can do to help.

 

Literature Cited

  1. J. Collie, O. Granela, E. B. Brown, A. C. Keene, Aggression Is Induced by Resource Limitation in the Monarch Caterpillar. iScience. 23, 101791 (2020).
  2. N. Barve, A. J. Bonilla, J. Brandes, J. C. Brown, N. Brunsell, F. V. Cochran, R. J. Crosthwait, J. Gentry, L. M. Gerhart, T. Jackson, A. J. Kern, K. S. Oberhauser, H. L. Owens, A. T. Peterson, A. S. Reed, J. Soberón, A. D. Sundberg, L. M. Williams, Climate-change and mass mortality events in overwintering monarch butterflies. Revista Mexicana de Biodiversidad 83: 817-824 (2012), doi:10.7550/rmb.26460
  3. H. Schroeder, A. Majewska, S. Altizer, Monarch butterflies reared under autumn-like conditions have more efficient flight and lower post-flight metabolism. Ecological Entomology. 45 (2020), doi:10.1111/een.12828.
  4. D. A. Green, M. R. Kronforst, Monarch butterflies use an environmentally sensitive, internal timer to control overwintering dynamics. Molecular Ecology. 28, 3642–3655 (2019).
  5. A. Agrawal, Monarchs and Milkweed: A Migrating Butterfly, a Poisonous Plant, and Their Remarkable Story of Coevolution (Princeton University Press, 2017)
  6. A. R. Masters, Temperature and thermoregulation in the monarch butterfly. Natural History Museum of Los Angeles County Science Series. 0, 147–156 (1993).

 

Image Permissions

"Monarch Butterfly" by Dave Slater is licensed with CC BY 2.0. To view a copy of this license, visit https://creativecommons.org/licenses/by/2.0/

"Monarchs Butterflies Back" by Sandy/Chuck Harris is licensed with CC BY-NC 2.0. To view a copy of this license, visit https://creativecommons.org/licenses/by-nc/2.0/

Will CO2 Emissions Bring On The Downfall of Sea Butterflies?

Author: Morgana Kimbrough

What the flutter is a sea butterfly?

At the heart of the polar ocean food web lies the tiny, yet beautiful Limacina helicina antarctica, a member of the group of zooplanktonic sea snails known as pteropods or more commonly, sea butterflies. Their shells are only 6mm wide, with wing-like extensions so that these tiny snails appear to “fly” through the water as they beat their appendages to swim (2). These tiny mollusks spend their entire lives free floating in ocean currents and feed on microscopic algae in the water using a web of mucus that can extend to many times the size of their bodies (2). You can read more about the general species characteristics of Limacina helicina antarctica in this article.

 These little creatures may seem small and unimportant but they are actually a main component of their food web, making up one fourth of the zooplankton in their community (2). Since they are so abundant, sea butterflies are preyed upon by many members of the polar ecosystem such as other zooplanktonic organisms, numerous species of fish, baleen whales, and even some sea birds. Because they have so many predators that count on their populations being abundant, sea butterflies are considered to be a critical species for the health and ongoing vitality of the polar oceans. Unfortunately, sea butterflies are threatened by changes going on in the ocean due to anthropogenic effects which may have serious consequences for the health of this food web.  

How is burning fossil fuels affecting the sea butterfly’s environment? 

Fossil fuels are one of the main ways that humans create the power we need to fuel our daily lives. Unfortunately, these fuels are not a clean resource and when we burn them we release pollutants into the atmosphere (2). One major pollutant released is carbon dioxide, or CO2. While we mostly think of this greenhouse gas as hanging out in the air, a lot of CO2 actually dissolves into seawater, making the ocean the largest sink for atmospheric CO2. This may sound good because less greenhouse gas in the atmosphere means a healthier planet, but all the dissolved CO2 actually wreaks havoc on the delicate balance that is the chemistry of ocean water. When CO2 dissolves into the ocean, it lowers the pH, which makes the water more acidic while also reducing the amount of available carbonate ions (2). Ocean acidification is suspected to have an impact on most marine life but it’s the lower levels of carbonate ions that could really spell trouble for the little sea butterfly (1). 

Why are sea butterflies uniquely vulnerable to acidic/low calcium ion conditions?

If fossil fuel emissions continue as they are today, it is predicted that by 2050 seawater in the polar ecosystems will be significantly undersaturated with carbonate ions (2). This may be severely detrimental to sea butterflies because during development, these organisms pull carbonate ions out of the water in order to grow their shells, skeletons, and other internal structures (1). Sea butterflies are suspected to be especially vulnerable to acidic and low carbonate ion conditions during their younger life stages as setbacks during development can have lifelong effects (1). For example, sea butterfly shells are known to develop to a smaller size, have significant deviations from typical shell shape, develop small holes, and overall show signs of corrosion when exposed to acidic water conditions (1). These developmental mishaps are a serious problem for the overall health and survivorship of all sea butterfly species. Read more about the effects of ocean acidification on sea butterfly shells here.  

How else does ocean acidification affect sea butterflies?

The process of ocean acidification affects more than just the shells of the sea butterfly. Overall survivorship of young sea butterflies raised in acidic conditions is only 61%. This means that improper development of the sea butterfly’s carbonate structures can cause mortality before they’re even done growing. Not only are some sea butterflies dying before they reach maturity, but the ones that do reach maturity struggle with their metabolic processes. It has been shown that oxygen consumption (one way to measure metabolism) was suppressed by 20% in sea butterflies living in acidic water (4). The sea butterflies are physiologically equipped to handle short periods of metabolic suppression, but in the long term, suppressed metabolism can lead to a reduction in growth and reproductive ability (4). These reproductive struggles in acidic conditions have also been studied revealing that the amount of eggs produced shrank by 50% and that the eggs that were produced were significantly smaller (3). The rate of development of these eggs was also hindered by exposure to acidic conditions (3). All this data makes it clear that ocean acidification is a big deal when it comes to these tiny organisms. More about the reproductive struggles of the sea butterfly in acidic waters can be found in this article. 

What’s next for the sea butterfly? 

If the acidification of the ocean continues as currently predicted, the sea butterfly population will be in big trouble. Considering what we already know about the sea butterfly’s crucial role in the polar ocean food web, the downfall of this species could have disastrous effects on the stability of their entire ecosystem. Without bountiful sea butterfly populations, there won’t be enough food supply for all the animals that feed on them, causing the populations of those animals to go down. Then whatever feeds on the animals that fed on sea butterflies will also not have enough food available, causing a cascading effect of populations decline all the way up the food web. With this small mollusk suddenly seeming very important, what can you do to protect these unique and important organisms? The simple answer is cutting back global CO2 emissions. However, achieving this goal is not so simple. There are ways for individuals to be more mindful of their CO2 output (see this factsheet with tips on carbon footprint reduction from the University of Michigan) and doing what you can to reduce your own carbon footprint in your daily life is good for the health of our planet. Unfortunately, taking these actions at the individual level can only do so much when the majority of carbon emissions are linked to big industry. The system we have set up on a global level by relying on fossil fuels for energy is a problem that is best solved by lawmakers who can put into effect policies like The Paris Agreement for example. This is why voting for elected officials who care about climate change is one of the most important things you can do for the health of our planet.

 

Citations

  1. J. Gardner, C. Manno, D. C. E. Bakker, V. L. Peck, G. A. Tarling, Southern Ocean pteropods at risk from ocean warming and acidification. Marine Biology. 165 (2017), doi:10.1007/s00227-017-3261-3.
  2. B. Hunt et al., Pteropods in Southern Ocean ecosystems. Progress in Oceanography. 78, 193–221 (2008), doi:10.1016/j.pocean.2008.06.001.
  3. C. Manno, V. L. Peck, G. A. Tarling, Pteropod eggs released at high pCO2 lack resilience to ocean acidification. Scientific Reports. 6 (2016), doi:10.1038/srep25752. 
  4. B. A. Seibel, A. E. Maas, H. M. Dierssen, Energetic Plasticity Underlies a Variable Response to Ocean Acidification in the Pteropod, Limacina helicina antarctica. PLoS ONE. 7 (2012), doi:10.1371/journal.pone.0030464. 

Image Credit

“Limacina helicina” by Russ Hopcroft, Institute of Marine Science, University of Alaska Fairbanks (UAF) and NOAA is in the public domain because it contains materials that originally came from the U. S. National Oceanic and Atmoshperic Administration, taken as part of an employee’s official duties. More information can be found here https://oceanexplorer.noaa.gov//backmatter/faqs.html and here https://oceanexplorer.noaa.gov/explorations/05arctic/background/biodiversity/media/limacina_helicina.html.

“Ocean Acidification Infographic” by Biochemlife is licensed under the Creative Commons Attribution-Share Alike 4.0 International license. To view a copy of this license visit https://creativecommons.org/licenses/by-sa/4.0/deed.en

New CitizAnts of the City

Authors: Craig D’Innocente, Elizabeth Leece, Patrick Jay Quizon

New CitizAnts of the City

By: Craig D’Innocente, Elizabeth Leece, and Patrick Jay Quizon

Did you know that ants organize their own systems similar to humans? Atta Sexdens, commonly known as leaf-cutter ants, organize their colonies into castes to structure their civilizations using abundant foliage. The phenomenon of agriculture was once marked as human only, but leaf-cutter ants are farmers just like us! Vegetation brought in from outside the colony is processed by the ants to provide a growing medium for mushrooms, most commonly of the Lepiotaceae variety. The fungus protects the colony from other insects, parasitic fungi, and provides a nutritious food source. This coevolutionary relationship is known as mycophagy. Originating in the tropics of South America, the range of leaf cutter ants continues to spread into agricultural lands and urban cities. With warming temperatures, A.sexdens heat tolerance allows for colonies to enter a positive feedback loop, increasing their foraging rate thus their colony size, reproduction rate, and range limit. The systems emerging from these colonies may be fascinating to observe in nature, however, as they extend into human centers their interactions may not be so pleasant. 

Caste System

In order to maintain a colonies’ garden, a caste system has evolved along with seasonal patterns. Within the colony, workers are divided into 4 major castes (1); commonly differentiated by head width (ranging from 0.6mm-1.2mm head width). Small workers commonly referred to a nurse ants (~1.0mm) watch over the garden to make sure that it does not become affected by pathogens or other sources of diseases. The nurses, as well as the slightly larger within-nest generalists (~1.4mm), are also in charge of managing the growth and breeding of the fungal gardens as well as the entire colony. The food for the garden is provided by even larger forager ants(~2.2mm). Forager ants travel to nearby vegetation and harvest the leaves so they can provide nourishment to the gardens. On their way, foragers trail back and forth from sources of leaves to the colony, exposing the colony to potential invaders. In order to protect the ants and the colony, soldier ants, called Defenders (~3.0mm) guard the nest. These ants are easily distinguished from the other ants because of their large head which contains massive teeth, which can easily intimidate any threats to the colony, its gardens, and its citizens. The most important role of the soldier ant is to provide protection to the queen, the most vital individual in any ant colony: their survival means the survival of the colony as a whole! Queen ants are easily the largest ants in the entire colony, as they can grow as big as 25.4 mm (1 in). Queens strictly create eggs to replace and expand the colony. Although this is a seemingly easy task, the amount of eggs a queen produces is positively correlated how much energy the colony creates in their gardens (2). Bigger gardens means more nutrients for the queen, which in turn means more members of the colony. In late Fall, the queen will begin to mate. With enough sperm, an exciting event takes place called nuptial flight, the queen flies away from her old nest, up to 11km away and burrows into the ground to begin egg-laying. Leaf-cutter ants are some of the few species of ants that practice polyandry, which means that they can have multiple queens in one colony. A.sexden queens are also the most long-lived and fertile insects, with 96-100%; creating a “large and complex society” (3). The changes in the reproduction of the species have massive effects to their overall population and fitness. 

  1. sexdens are known to be an “aggressively territorial species” (1), expanding their colonies in all directions if given abundant foliage. The success of colonies depends on multiple factors including queen fertility and vigor, preservation of fungal garden, and temperature (2). As the temperature continues to rise, leaf-cutter ants are evolving to withstand not only these disturbances, but also the disturbances inflicted by human development.

Life in the City

As humans begin to urbanize many parts of the tropics, new towns and cities are becoming more common. These cities increase local temperatures since materials used for construction have high heat absorbance. What this means is that these materials (such as cement and asphalt) have a tendency to absorb and hold heat. Cities have become literal hotspots for both temperature and leaf-cutter ant colonies. Due to urban expansion into leaf-cutter habitat, colonies are found near city roads with increasing concentrations, profiting off of human disturbance (4). These colonies exhibit a higher heat tolerance following along the roads. Rather than invading human homes or dumpsters, leaf-cutter ants typically prefer outdoors spaces with abundant foliage.

Urban dwelling for leaf-cutter ants is due to their increased activity in warmer temperatures. Warmer temperatures increase foraging rates, which means that surrounding vegetation will become likely targets as nutrient sources for their fungal gardens (5). This acts as a positive feedback loop. Increased foraging leads to larger fungal gardens, which increases a colonies’ energy production; which allows the colony to produce more queens, and ultimately more offspring (2). Eventually, a colony will produce excess queens, who will leave their birth colony to start their own colony elsewhere (6). With increasing urbanization of the tropics, this means that it is more likely that queens have already begun their new colonies next to the cities. 

The People of the City

We already know what city living means for leaf-cutter ants, but what does it mean for the human inhabitants of the cities which they colonize? Leaf-cutter ants may not have as much of a direct impact on humans as other, more pesky ant species (like the ever present argentine ant), but they still manage to interact with humans. Rather than invading human homes or dumpsters, the threat leaf-cutter ants pose to human dwellings is outdoors, in our gardens and parks. Before going any further, this is not meant in any way to demonize leaf-cutter ants. Any damage they do to human establishments is due to large urbanization developments, and other anthropogenic effects which affect their nesting habits. Leaf-cutter ants might tend to their own garden and keep it safe, but that does not mean that they will protect and improve the ones created by people.

Agricultural Ants in Human Agriculture

That being said, leaf-cutter ants can pose a substantial threat to both local agriculture and agribusiness, as well as essentially anything else humans choose to grow. Leaf-cutter ants have been known to strip citrus trees of their leaves completely in 24 hours (7). This is like a garden competition, except sabotaging the work of others is allowed. 

Threat to agriculture does not go unnoticed by farmers, who have made a grand effort to protect their crops from destruction. Unfortunately, what this means for leaf-cutter ants and other flora and fauna is a deluge of pesticides. Pesticides are a huge threat to basically everything in the natural world, with their only benefit being protection for crops. As it stands, pesticides are likely the greatest direct threat to leaf-cutter ants as a species (8). And as habitat loss continues to be exacerbated by human development, leaf-cutter ants will continue to establish colonies next to cities and human establishments. This will lead to human produce being destroyed by leaf-cutter foraging, which will make humans search for ways of staving off defoliation. 

The True Enemy

The final threat to leaf-cutter ants, as is true for nearly every species, is climate change. Even though leaf-cutter ants have been shown to react well to high temperatures, there is undeniably still an upper limit to their heat tolerance. Indeed, because of their above average heat tolerance, conservation efforts may leave leaf-cutter ants behind. Regardless of how well they may be able to tolerate heat at this point in time,  they will still be affected by climate change just like every other species on Earth. 

What Can be Done

Atta Sexdens exhibit adaptations to respond to disturbances; however, we are still unsure of the long-term consequences of climate change and human disturbance. Although there is evidence for tolerance within observed populations, it is hard to assess the challenges within ant and human interactions. Creating natural habitats is important for all ecosystem functioning. The physiology of the species greatly depends on the ability to obtain resources within their environment.

People have begun movement to help mitigate the drastic changes in the world. Team trees began a campaign asking everyone in the world for donations (9). One tree will be planted for every dollar donated to the program. 20 Millions trees will lead to many changes to both the world and people (10). This program not only slows down the effects of climate change, it also provides and maintains new locations for leaf-cutter ant habitats and colonies.

 

Images belong to Wikipedia and Pixabay respectively


Citations

References

 

  1. A. Byrne, “Atta sexdens” (Animal Diversity Web, University of Michigan. 2004)
  2.  A. A. Moriera, L. C. Forti, R. S. Camargo, N. S. Nagamoto, N. Caldato, M. A. Castellani, V. M. Ramos, Variation in nest morphology, queen oviposition rates, and fungal species present in incipient colonies of the leaf-cutter ant Atta sexden. Tropical Zoology. 32, 107-117 (2019).
  3. S. E. F. Envision, W. O. H. Hughes, Genetic caste polymorphism and the evolution of polyandry in Atta leaf-cutting ants. The Science of Nature, 8, 643–649 (2011).
  4.  F. F. S Siqueira. J. D. Ribeiro-Neto, M. Tabarelli, A. N. Andersen, R. Wirth, I. R Leal, Leaf-cutting ant populations profit from human disturbances in tropical dry forest in Brazil. Journal of Tropical Ecology. 33, 337-344 (2017).
  5. H. G. Fowler, S. W. Robinson, Foraging by Atta sexdens (Formicidae: Attini): seasonal patterns, caste and efficiency. Ecological Entomology. 4, 239-247  R. T.
  6. Fujihara, R. S. Camargo, Luiz Carlos Forti, Lipid and energy contents in the bodies of queens of Atta sexdens rubropilosa Forel (Hymenoptera, Formicidae): pre-and post-nuptial flight. Rev. Bras. entomol. 1 (2012).
  7. The Bug Master. “Leaf Cutter Ants.” The Bug Master, 6 Feb. 2017, https://www.thebugmaster.com/leaf-cutter-ants/.
  8. J.S Britto , L.C. Forti, M.A. de Oliveira , R. Zanetti , C.F. Wilcken , J.C. Zanuncio , A.E. Loeck , N. Caldato , N.S. Nagamoto , P.G. Lemes, R.S. Camargo, Use of alternatives to PFOS, its salts and PFOSF for the control of leaf-cutting ants Atta and Acromyrmex. International Journal of Research in Environmental Studies 11-92(2016)
  9. “Help Us Plant 20 Million Trees - Join #TeamTrees.” #Teamtrees, teamtrees.org/.
  10. “Planting 20,000,000 Trees Will Actually Have This Impact”, Youtube, https://www.youtube.com/watch?v=-cPdImejxEQ&t=1s

The Common Octopus May Stop Being Common Due to Climate Change

Authors: Ted Espinola, Kai Houston, Sean Kim, Sean Lee


The Common Octopus, Octopus vulgaris, might not be so common if the temperature keeps rising. The Common Octopus is a common species of octopus, hence the name, found in the Atlantic Ocean near the coasts of most countries. (1) If you’ve ever had any octopus or octopus-flavored foods before you’ve likely eaten this animal. Part of the reason that they are so commonly eaten is because of how common of a species it is. They can grow up to 2 meters long with the arms being about 1 meter long. The mantel, the head of an octopus, holds all their major organs. (2) They also employ camouflage where they can change the color and texture of their skin at will to blend in with their environment. (3) Though currently they are common and plentiful, climate change is likely to bring about a big change to the distribution of this species, maybe to such an extreme that the name “common octopus” may become misleading.

The amount of Common Octopuses in the water changes with the climate, predominantly with the temperature of the ocean waters. There are several factors that influence population size of the common octopus, but studies have shown that water temperature is one of the most influential factors in population size. Cold water leads to a bigger population sizes whereas warm water leads to smaller population sizes. Simply put this means that the Common Octopus is more common in cool waters and less common in warm waters. This was shown by a research paper that compared the sea surface temperature and the catch sizes by fishermen. Through decades, the trends showed there were more octopuses caught when the temperatures were low. The yearly variability of the water temperature has been recorded for decades and shows that the temperature is rising steadily. The long term effects of climate change has lead to smaller and smaller populations. (4) If this trend continues, the diminishing populations may lead to the consideration of the common octopus as a nomination for an endangered species. 

To understand why climate change will impact this species so greatly we need to discuss how temperature affects the species. The most important aspect to understand is that octopus eggs rely almost entirely on their ambient water temperature to control how and when to develop their organs and tissues. The Common Octopus lays their eggs in shallow water, where the ocean is the warmest, and this can lead to serious issues when considering the increasing water temperature as a result of climate change. (4) Octopus eggs depend on their ambient water temperature to control their growth, and they are pretty picky about it. Warm water makes the octopuses hatchlings ramp up growth and hurry up and hatch, going far enough as to neglect safety in extreme cases. With as little as a 3 degree Celsius increase in water temperature the mortality rate of octopuses can go up 30%. (5) That’s worrisome when considering the impact climate change is already having on our oceans and the continuing changes it will have over time. 

Another aspect that ocean water temperature regulates is energy expenditure. (6) The warmer water makes the octopuses spend more energy to maintain its biological and physiological balance; this means the octopuses need to eat more, which requires more energy to be spent hunting. This creates a cycle that could lead to energy deficits because of the limited resources octopuses have access to. When octopuses eat food, their metabolic rate increases to facilitate the processes required to consume and digest the food; this is a phenomenon called Specific Dynamic Action (SDA). Although the costs of feeding are similar at different temperatures, their oxygen consumption rate is higher at colder temperatures than at higher temperatures. SDA requires less energy overall at lower temperatures than at higher temperatures which means as ocean temperatures rise, their energy expenditure for SDA increases. (7) Octopuses need more food to provide the energy lost in primary functions when dealing with high temperatures, which could negatively affect their growth rates and other functions.

These octopuses have inversely linked protein and energy usage. This means the more energy they use, the less proteins they produce. (6) Protein production is important for their growth as more protein tends to mean bigger bodies. As the water in the ocean continues to rise in temperature, the average size of an octopus will continue to decrease due to reduced protein production. It is known that the smaller the octopus, the less successful they are at hunting and therefore it’s more energy expended on failed huntings. (7) The warming waters changes in the way octopuses use their resources and creates a positive feedback loop. (6)

These common octopuses are a part of an ecosystem that contribute to both their environment and our human needs. With higher temperatures due to climate change, octopuses are changing the way they behave and develop in ways that often times hinder their survival. Birth rates, population size, and energy distribution are all affected drastically with slight changes in temperatures. (4-7) Climate change is reshaping the ecosystem of these invertebrates, which is leading to reducing their population numbers. If climate change continues on the path and rate that it is going, many species we identify as common may find themselves heading down the same path as the common octopus. If you enjoy eating octopus, know that it may become a rare delicacy should they be considered an endangered species, as using them for food would most likely be banned for conservation purposes. What we can do to help them and many other species is by reducing our carbon footprints. Using less fossil fuels, recycling, and investing in renewable energy sources are all helpful for the environment. Also consider getting in touch with local conservation centers and seeing if there are volunteer opportunities. Individually we can make little changes to help and as long as we do our part, the Common Octopus will still be around to be a tasty treat.


Citations

1. K. M. McConnell, K. Scott, Prey species preference and specialized feeding behavior in the Mediterranean Octopus Vulgaris, (2010)

2. Norman, M.D. Cephalopods:A World Guide. Conchbooks (2000)

3. K. Harmon, How Octopuses Make Themselves Invisible [Video], (2012)

4. M. Vargas-Yáñez, F. Moya, M. García-Martínez, J. Rey, M. González, P. Zunino, Relationships between Octopus vulgaris landings and environmental factors in the northern Alboran Sea (Southwestern Mediterranean). Fisheries Research. 99, 159-167 (2009). 

5. R. Tiago, M. Baptista, MS. Pimentel, et al, Developmental and physiological challenges of octopus (Octopus Vulgaris) early life stages under ocean warming. Journal of Comparative Physiology B. 184, 55-66 (2013).

6. H. Miliou, M. Fintikaki, T. Kountouris, G. Verriopoulos, Combined effects of temperature and body weight on growth and protein utilization of the common octopus, Octopus vulgaris. Aquaculture. 249, 245–256. (2005). 

7. S. Katsanevakis, N. Protopapas, H. Miliou, G. Verriopolous, Effect of temperature on specific dynamic action in the common octopus, Octopus vulgaris (Cephalopoda). Marine Biology. 146, 733–738 (2005).

 

Images:

https://en.wikipedia.org/wiki/Common_octopus

https://www.epa.gov/climate-indicators/climate-change-indicators-sea-surface-temperature

The Common Octopus is Facing Even More Common Problems, and It’s Our Fault

Authors: Piper Evans, Agostina Galluzzo, Marissa Hernandez, Taylor Hauenstein

Octopus vulgaris, better known as the common octopus, is part of the class Cephalopoda. These octopuses are abundant in Mediterranean waters, as well as in the East Atlantic coasts. Like other octopus, they have 8 arms and lack an internal skeleton, reaching a length of 1-3 feet, including their arms, and a mass of 180-874 grams. They sustain themselves off small fish and crabs [1] [2], and live in depths ranging from 0-200 meters, decreasing in abundance with depth [3]. However, the common octopus is not “common” in the slightest; with extreme intelligence and no skeletal structure, the octopus has been known to be able to squeeze through any opening larger than its beak [4]. Their brain contains two enlarged areas that are specialized for memory storage. Stories have been recorded of octopuses in captivity being able to dismantle plumbing, escape their tanks, and even exhibit playful behavior, like squirt water to turn off lights [5]. As intelligent as they are, octopuses are in serious threat as we continuously expose them to the aftermath of human activity.

Most recently, with the issue of ocean warming and toxic pollution becoming more prominent, research has been focused on how increasing temperature and chemical waste affects this intelligent species both directly and indirectly. More specifically, how does this impact the unique life of a common octopus? There have been a few different studies on this subject that shows how changes in temperature and pollution could potentially alter the O. vulgaris way of life in immense ways. 

A warming ocean can have detrimental effects on an octopus starting from the moment they are laid as eggs. A 2013 study by Repolho et al. has shown that an increase in water temperature by only 3°C will negatively affect a developing octopus by enabling it to hatch prematurely, decreasing its chance of survival. In this way, an increase in temperature can be a direct cause of the decrease in abundance of our octopus friend.

Temperature will still be affecting O. vulgaris once the octopus reaches maturity as well. A study conducted in 2004 by researchers Katsanevakis et al. looked at how temperature might be affecting the metabolic rates of the common octopus. The metabolic rate is the amount of energy it uses per unit of time. Metabolic rates have a huge impact on animals, determining if and how they grow among other important biological aspects. Comparing octopuses living at 20°C and 28°C, the researchers found that octopuses living at higher temperatures had a significantly higher standard metabolic rate than those living at the lower temperature. This means that at higher temperatures, the octopus is having to expend a lot more energy on a day to day basis, limiting their overall growth.  

Not only are ocean temperatures on the rise due to climate change, it’s also being heavily polluted and acidifying faster than ever before. As humans continue to dump waste into the ocean, there have been numerous side effects found that can potentially destroy marine life. For Octopus vulgaris this means that they are having to deal with different metals and chemicals entering their habitat and severely affecting their ability to survive and thrive. It was shown in a study by Nicosia et al. that chemicals such as cadmium have negative effects on both growth rate and mortality rate of the common octopus. Cadmium is a chemical found in plastics, glass, batteries, and many other common ocean pollutants. The study found that after being exposed to cadmium, octopuses synthesize a heat shock protein called hsp70 that is used to prevent damage and is a general response to stress for the octopus. Because this protein was made by the octopus at such high levels when exposed to even small amounts of cadmium, it was concluded that the presence of cadmium is a major source of stress. In order to have enough energy be put into making these protective proteins needed for survival means that the octopus is forced to inhibit its own growth and decrease its chance of survival. 

Pollution determines the fate of the common octopus in more ways than one. As humanity continues to dump cosmetics and other man-made materials into the ocean, the immune system of the octopus is forced to fight off the chemical bombardment that comes with it. Immune systems are what allows animals to fight off potentially life-threatening diseases. If it is overworked or dysfunctional, then the animal is more likely to suffer from sickness or other related ailments much worse than the common cold. Titanium dioxide nanoparticles (nTiO2) are one of the lethal byproducts of human pollution that is affecting this species. This chemical is commonly found in cosmetics, sunscreens, and toothpaste, and is generally considered safe in terms of animal welfare according to the F.D.A. However, one study has shown that it may not be as safe as once thought. In 2013, researchers Grimaldi et al. performed experiments in order to see if nTiO2 would trigger a response in the immune system of the common octopus, and it did! The response showed an increase in lysozyme activity, hemocytes, and nitric oxide, the

main elements that enable an octopus to fend off diseases and foreign substances and keep them from deteriorating. The fact that they are responding to titanium dioxide shows that their immune system is being overworked and can potentially lead to more complications and even death. 

While this information is useful, more questions have arisen from these studies than answers. One thing is clear: these anthropogenic effects are taking their toll on this clever creature. From external morphological growth down to protein synthesis, warming temperatures and toxic pollution are negatively affecting one of the most abundant octopus species. However, this evidence doesn’t mean all hope is lost for our tentacled friend. Looking forward, scientists can continue research to find out which pollutants being dumped are harming marine animals the most. The same can be done to find solutions for the effects of rising temperatures. But there’s even smaller steps that we can all do to help; it may seem small, but being mindful of what we wash down our drains can make a huge difference. Try to avoid products with titanium dioxide nanoparticles and look for “non-nano” kinds (like sunscreen) instead! Even simple things like limiting your plastic waste and using natural cosmetics and home goods can make a huge difference. That way, our ocean friends like the common octopus can look forward to a healthy future full of play.




Citations

[1]  Nicosia, A., Salamone, M., Mazzola, S., Cuttitta, A. (2014).Transcriptional and Biochemical Effects of Cadmium and Manganese on the Defense System of Octopus vulgaris Paralarvae. BioMed Research International, 2015:1–11

[2]  Grimaldi, A. M., Belcari, P., Pagano, E., Cacialli, F., Locatello, L. (2013). Immune responses of Octopus vulgaris (Mollusca: Cephalopoda) exposed to titanium dioxide nanoparticles. Journal of Experimental Marine Biology and Ecology, 447:123–127

[3] Katsanevakis, S., Protopapas, N., Milou, H., Verriopoulos, G. (2004). Effect of temperature on specific dynamic action in the common octopus, Octopus vulgaris (Cephalopoda). Marine Biology, 146:733-738.

[4] https://www.scientificamerican.com/article/are-octopuses-smart/

[5] https://www.npr.org/templates/story/story.php?storyId=96476905?storyId=96476905

[6] Repolho, T., Baptista, M., Pimentel, M. S., Dionısio, G., Trubenbach, K., Lopes, V. M., Rita A. L., Calado R., Diniz M., Rosa R. (2013). Developmental and physiological challenges of octopus (Octopus vulgaris) early life stages under ocean warming. Journal of Comparative Biology 2014, 184:55-64. 

 [7] Sobrino, I., Silva, L., Bellido, J. M., & Ramos, F. (2002). Rainfall, river discharges and sea

temperature as factors affecting abundance of two coastal benthic cephalopod species in the

Gulf of Cadiz (SW Spain). Bulletin of Marine Science, 71(2), 851-865.



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