The Arctic & Antarctica
The Arctic and Antarctica are distinct polar regions on opposite ends of the Earth. While both are characterized by cold temperatures and ice-covered landscapes, they differ in geography, climate, and wildlife. The Arctic is an ocean surrounded by landmasses and is home to species like polar bears and Arctic foxes, while the Antarctic is a massive continent entirely covered by ice, with penguins and seals inhabiting its coastal areas. In terms of climate, the Arctic experiences milder temperatures compared to Antarctica's extreme cold, with its sea ice being more dynamic. Despite these differences, both regions are affected by climate change and have drawn attention to their ecological significance and potential resource extraction due to melting ice.
- Analyze the role of krill in polar ecosystems, specifically their importance as a primary food source and their impact on carbon cycling.
- Evaluate the impact of human activities, such as commercial fishing, on krill populations and the subsequent effects on marine ecosystems and species like whales.
Next Generation Standards
LS4.D: Biodiversity and Humans
Construct an argument supported by empirical evidence that changes to physical or biological components of an ecosystem affect populations.
LS2.C: Ecosystem Dynamics, Functioning, and Resilience
Evaluate the claims, evidence, and reasoning that the complex interactions in ecosystems maintain relatively consistent numbers and types of conditions, but changing conditions may result in a new ecosystem.
Habitats & Adaptations
The Arctic and Antarctica boast unique habitats that have given rise to distinctive adaptations in their resident species. In the Arctic, characterized by fluctuating temperatures, animals have evolved various mechanisms to cope with the cold, including specialized insulation and camouflage. Similarly, in Antarctica's extremely cold environment, species have developed features such as efficient heat retention and streamlined bodies to survive. These adaptations underscore nature's ability to flourish in the face of the demanding conditions posed by polar regions.
Krill are tiny, shrimp-like crustaceans that feed on phytoplankton in the water column. With levels ranging from 125 million tons to 6 billion tons in the Antarctic, their influence on the ecosystem is unparalleled. Specifically, Antarctic krill (Euphausia superba) can reach lengths of 60 mm and weigh up to 2 grams. During certain seasons, their swarms in the Arctic oceans can be seen from space and are estimated to remove 35% of the carbon in the region.
There are over 85 known species of krill, with an average size of a human pinky. Like shrimp, krill swim in swarms to protect themselves against predators, rising to the surface at night and sinking to the depths in the daytime. This contributes to the deep scattering layer, which was discussed in a previous lesson! These creatures are capable of spawning 10,000 eggs at a time. Even more impressive is their reproductive cycle which allows them to give birth several times during their spawning season of January to March. These eggs sink the seafloor and hatch in 10 days with a lengthy lifespan of 10 years, if they can avoid being eaten.
Interestingly, ocean animals aren’t the only ones consuming these little creatures. Krill is commercially fished to be used as livestock feed, bait, as well as for human consumption. Their bodies are extracted for their Omega-3 fish oil, or dried to be used in different dishes.
In many Asian cultures, these crustaceans are used as a flavor enhancer with their signature “umami” taste. For example, they are often added to egg dishes or sauce bases. In China, the dried product is called xia mi, directly translating into shrimp rice due to its tiny size. However, this product is not widespread in Western culture, and the easily available larger shrimp from the Gulf of Mexico is mainstream.
However, the future for krill isn’t stable. With insufficient nutrition from the shrunken ocean zones where the krill thrive, their body size is naturally reduced, decreasing the available biomass for the creatures dependent on them. In addition, increased pressure from commercial fishing is pressuring the krill population, creating extra competition for whales and similar creatures.
Antarctic krill (Euphausia superba) are adapted to blend into their icy marine environment with a transparent-like appearance. This is due to the cellular arrangement of their thin exoskeleton, colorless pigments, and microscopic structures that scatter light.
Image: Antarctic krill in the water.
Whales are creatures of the order Cetacea, encompassing whales, dolphins, and porpoises. These animals are warm-blooded and a product of convergent evolution. Their body is fish-like with a streamlined shape, dorsal fin, and fluke (tail). Their nostrils also became the blowhole on the top of their head.
There are roughly 90 species of whales, with two main orders of Mysticeti (Baleen Whales) and Odontoceti (Toothed whales). Baleen whales are filter feeders, taking in large amounts of water through their baleen plates to capture krill and other prey. Baleen plates are rows of flexible, fibrous plates in the upper jaw made of keratin with bristles that overlap in the upper jaw. Toothed whales have teeth, allowing them to eat larger organisms such as fish, squid, and other prey. However, their teeth are used to catch the prey, and it is swallowed whole where it is ground up in one of their three stomachs.
Bowhead whales utilize the Arctic ice as a means to navigate beneath the surface, effectively evading predators. The frozen cover of the ice also enhances communication among whales. During the fall, these creatures historically migrate southward, tracing the newly formed ice in the Bering Strait—a more navigable and breathable alternative compared to the dense, perennial Arctic ice. Over the years, a noticeable trend has emerged, with sea ice decreasing by approximately 13% per decade since 1979. Consequently, the Arctic waters remain unfrozen later into the fall season, characterized by a thinner ice layer. This shift is leading to prolonged open periods in the Bering Strait, significantly impacting the migration patterns of these animals.
Whales in the Arctic
Did you know that the blubber layer acts as a natural insulator, helping whales maintain a stable body temperature even in the coldest conditions? Not to mention, this layer also contributes to a whale's buoyancy control by helping them conserve energy while swimming and diving, as they can adjust their depth with minimal effort.
Image: A Bowhead whale coming up for air.
The Arctic zone acts as a transition area between the Atlantic and Pacific Oceans, receiving water from the Pacific and releasing it into the Atlantic through the Fram and Bering Strait. The mixture of varying salinities and temperatures forms a distinct water mass. Two-thirds of the freshwater inflow comes from Eurasian and Russian rivers, reducing the Arctic Ocean's salinity. The ocean's stratification is due to temperature and salinity differences, resulting in distinct layers. Freshwater influx from melting ice creates a sharp halocline and thermocline in the upper regions, while wind-driven currents stir the top 5-10 meters of water, leaving deeper layers untouched. These water masses contribute to a global conveyor belt, circulating cold water and nutrients around the world to support ecosystems. In the Antarctic, the circumpolar current fosters a diverse ecosystem by isolating nutrient-rich waters. Seismic surveys, commonly used for oil and gas exploration, employ sound waves that can harm marine life like dolphins and whales. Despite environmental concerns, no economically viable alternatives currently exist, making this exploration method a necessary but harmful practice.
- Identify and explain the role of the Arctic and Antarctic in global ocean circulation and its impact on ecosystems worldwide.
- Analyze the use of seismic surveys and assess the need for alternative exploration methods.
Next Generation Science Standards
ESS2.D: Weather & Climate
Construct an argument supported by evidence for how increases in human population and per-capita consumption of natural resources impact Earth's systems.
ESS3.A: Natural Resources
Construct an argument supported by evidence to explore the impact of resource extraction in polar regions and how it affects the environment and ecosystem.
The Arctic zone is a transition between the waters of the Atlantic and the Pacific, taking in water masses from the Pacific and depositing them into the Atlantic. Through the Fram and Bering Strait, the water enters and exits the Arctic Ocean, mixing different salinities and temperatures to form a new type of water mass. However, a large portion of the freshwater entering the Arctic Ocean is from the Eurasian and Russian rivers, accounting for two-thirds of the total freshwater inflow. This inflow decreases the overall salinity of the Arctic Ocean, creating a lower salinity water mass than the Atlantic Ocean.
The stratification of the Arctic is created by a difference in temperature and salinity, creating layers that are starkly divided and rarely interact with one another. In the upper regions, the influx of freshwater caused by melting divides the region from the saltier bottom, developing a sharp halocline in the water column. In addition, solar heating creates a sharp thermocline only present in the top waters. Most importantly, wind-driven currents mix the top 5-10 meters of water on the top of the water column, and anything below is largely untouched by any other mixing forces. These water masses flow around the world in a global conveyor belt, bringing cold water and nutrients to upwelling zones, where productivity flourishes and ecosystems are supported.
Locally, the Antarctic circumpolar current is a key to supporting life in the colder regions. This current circles the Antarctic region, keeping away any warm waters from entering. With this thermally isolated and nutrient-rich isolated body of water, a great variety of life can be supported, and thus support an entire ecosystem. For example, krill can flourish in these waters, and support animals such as whales which migrate to these regions to feed.
Seismic surveys are used to discern the different layers in the ground by recording soundwaves that pass through different mediums. Explosives are commonly used to create these sound waves, but recent developments have led to the creation of air guns or water guns that produce similar effects without impacting the surrounding environment. After these waves travel through the water, they pass through the different layers of the suboceanic terrain, and the returning waves are recorded through a series of geophones trailed behind the ship to receive the signal. This method of surveying is largely used for oil and gas exploration, harming wildlife in the process. For example, dolphins and whales rely on sound to communicate and are extremely sensitive to sounds in the ocean. The ocean is a dynamic soundscape with a variety of constant noises across its depths. However, certain loud sounds from activities like seismic surveys can have unintended effects, occasionally affecting marine mammals. Presently, finding economically feasible alternatives for ocean floor surveys is a challenge. As a result, policymakers have recognized that while this form of exploration may have some environmental impacts, it is seen as a necessary step in understanding and harnessing resources from the ocean floor.
The Arctic is home to indigenous communities with deep ties to the land and sea. Artic subsistence living is characterized by the reliance on materials and resources from the natural environment. Preserving the traditional knowledge and ways of life in is significant for the sustainable management of Arctic resources. It is a way of life that has sustained communities for thousands of years and continues to be an essential part of their cultural identity and survival.
Image: An illustration showing the profound connection of Arctic communities to the land, ice and water.
The Changing Climate
Perhaps the most visible change is the receding ice sheet of the arctic region. From space, the area is a shrinking mass of white, and the area is getting smaller year by year. This change isn’t only geological, the ecology of the area is changing as well, disrupting feeding patterns of the arctic species and ones that reside near them. For example, orcas, a traditionally southern Arctic species, are pushing further north for feeding grounds and constant temperatures. If this trend continues, many new ecological niches would be overturned, and a new system would be created – to the detriment of many vulnerable species in the area.
As the sea water and surrounding air temperature rise, the ice melts causing an influx of fresh water in the sea. This changes the salinity of the surrounding sea water affecting many of the microorganisms in the water column. This melting is also responsible for about one-third of the sea level rise that we are seeing. Greenland is currently losing about 270 billion tons of ice per year. Many migrating mammals and Arctic animals call the large ice sheets their homes. Polar bears use the glacier to raise their young and as resting places on long hunting missions.
The changing climate in Antarctica is a pivotal component of the larger global climate change narrative. Situated as the southernmost continent on Earth, Antarctica is undergoing profound environmental shifts, and the implications extend well beyond its icy borders. These alterations in Antarctica's climate have extensive consequences, not only for the continent itself but also for the entire planet. The rapid warming, ice melt, and shifting precipitation patterns in Antarctica are emblematic of the broader climate challenges facing our world, underscoring the urgency of addressing climate change on a global scale.
- Investigate and explain the process of ice melting and iceberg formation within glacial movements.
- Analyze climate data to understand global climate change.
- Design and develop strategies for mitigating thee potential effects of climate change on wildlife and water quality.
Next Generation Science Standards
ESS2.C: The Roles of Water in Earth's Surface Processes
Plan and conduct an investigation of the properties of water and its effects on Earth materials and surface processes.
ESS3.D: Global Climate Change
Analyze geoscience data and the results from global climate models to make an evidence-based forecast of the current rate of global or regional climate change and associated future impacts to Earth's systems.
LS2.C: Ecosystem Dynamics, Functioning, and Resilience
Design, evaluate, and refine a solution for reducing the impacts of human activities on the environment and biodiversity.
The shrinking Arctic ice sheet is transforming the entire Arctic ecosystem. This change isn't limited to the geological landscape. The Arctic is home to a wide range of species, from seals to polar bears to various types of fish and marine mammals. The reduction in sea ice disrupts the feeding patterns and habitats of these species, leading to increased competition for resources.
Image: A pod of orcas hunting.
Melting Ice Sheets
Antarctica holds the largest volume of freshwater ice on Earth, and the melting ice contributes to rising sea levels worldwide. The West Antarctic Ice Sheet, in particular, has been losing mass rapidly.
Image: Melting ice sheets
Jökulsárlón Glacier Lagoon
Jökulsárlón, Located in southeastern Iceland and just outside the Arctic Circle, is situated at the edge of Vatnajökull, Europe's largest glacier. The lagoon itself formed in the 1930s when the outlet glacier began to retreat due to warming temperatures, leaving behind a deep, ice-filled lagoon. The lagoon's size has been expanding, as icebergs break away and enter into the lagoon.
Altered Sea Water Composition
The melting ice contributes to an influx of freshwater into the surrounding seawater. This influx alters the salinity of the marine environment.
Changes in salinity can affect the distribution and abundance of microorganisms in the water column, which, in turn, impacts the entire marine food chain. It can also affect the distribution of important prey species, which are crucial for many marine animals.
Image: Illustration of Earth's water supply.