What is a keystone species?
Definitions
We can define a keystone species as an organism that has a significant effect on its ecosystem, outweighing its population size.
Importance of Keystone Species
Because keystone species are incredibly important, their removal from an ecosystem can trigger an ecosystem collapse or a trophic cascade.
Every ecosystem has a role to play in the world. They provide humans with ecosystem services. If keystone species are removed this will have an impact on human livelihoods. Some ecosystem services we rely on are pollination for food, water purification and air purification.
Categories of keystone species
Keystone species fall into various categories, including predators, prey, ecosystem engineers, mutualists, and plants. These keystone species can influence ecosystem processes either from the top down (predators) or the bottom up (plants)
Key Terms
What is an ecosystem?
A community of living organisms (biotic) that live and interact with each other and the non-living environment (abiotic)
We can find natural ecosystems everywhere we look in the world. From rainforests filled with the most diverse plants and animals to coral reefs which are so vibrant in colour and life. Additionally, rivers which connect the land to the sea and are safe breeding grounds for migratory fish and birds.
For a river example, you will have living (biotic) components like fish, river invertebrates, birds, algae, and plants on the riverbank which all interact with each other. Then you will have the non-living (abiotic) components like the pH of the water, flow rates, the amount of sun the river gets, temperature of the water and the substrate at the bottom of the river e.g. sand or stones. Abiotic and biotic factors interact with each other to determine what can live in various parts of the river ecosystem. Ecosystems show that everything is linked as what happens on the land will determine what will happen in the river and vice versa.
What are Trophic Levels?
Trophic levels show the transfer of energy as it moves through the food chain. We can categorise trophic levels based on how the organism gets their energy. The length of the food chain determines how many trophic levels there will be. Trophic levels are shown as an ecological pyramid this is because of how much mass (biomass) there is at each step.
What Are Top-Down and Bottom- Up Trophic Effects?
A top-down effect is where the ecosystem is determined by the presence or absence of a top predator. This means that the predator controls the ecosystem and if it is not present the ecosystem will become unbalanced.
A bottom-up effect is where the ecosystem relies on lots of energy at low trophic levels. This then determines what species can live above them in the food web. It depends on how much primary production (plants photosynthesising) there is to feed the higher trophic levels.
What is a Trophic cascade?
A trophic cascade occurs when there is a disruption in the food chain. This disruption can happen in two ways: top-down or bottom-up. A top-down trophic cascade occurs when there is a decline in the population of the top predator in that food chain. A bottom-up trophic cascade happens when there is a decrease in the population of the producer (plant) of that food chain.
Where are keystone species found?
There are keystone species in every major ecosystem, but the amount will differ depending on what country you live in. Insect pollinators are the group of keystone species that you will find no matter where you are in the world, (apart from Antarctica). They are a group of many important individual keystone species for the pollination of plants. Go check out my previous blog post if you want to know how to help insects in your garden.
What is the IUCN Red List?
IUCN stands for The International Union for Conservation of Nature’s Red List of Threatened Species. It is the world’s biggest database on the global conservation status of animal, plant, and fungi species. The IUCN categorises species into nine levels with varying degrees of threat to the abundance of that species. The categories are Not Evaluated, Data Deficient, Least Concern, Near Threatened, Vulnerable, Endangered, Critically Endangered, Extinct in the Wild and Extinct. I talk about where the five keystone species groups sit on this scale below.
5 examples of Keystone species and how you can help them
Sea Otter
Sea otters are at the top of the aquatic food chain. Where otters are present, they create a trophic cascade, ultimately leading to an increased uptake of CO2. This cute species is found in North America, Russia and Japan.
Sea otters are predators of sea urchins, whose primary food source is kelp. In the absence of sea otters, the populations of sea urchins explode, eating large amounts of sea kelp. Sea kelp, an aquatic plant, grows by absorbing carbon dioxide and storing it. Kelp also serves as a primary producer in many ecosystems, meaning it is the foundation of the food chain, providing energy for other organisms.
This study revealed a difference in the carbon storage of kelp forests with and without sea otters. Areas with sea otters had much higher amounts of kelp, as the plants had an increase in Net Primary Productivity (NPP) and Biomass density. Net Primary Productivity is a measure of all plant’s annual productivity. Whereas Biomass density refers to the measure of the total mass of a species in an ecosystem at a specific time.
There are large economic benefits from an increased NPP and Biomass Density in kelp forests. Based on 2012 carbon prices, the carbon stored from the study site over 40 years could be valued between US $205 million and $408 million on the European Carbon Exchange. This highlights the major economic benefits of protecting sea otters, to help protect our environment in these changing times.
IUCN Red List Status and Threats
Unfortunately, Sea otters are classified as endangered on the IUCN red list. Human activities are the largest threat to this species. With entanglement in fishing nets, boat strikes and direct human conflict being major threats. As well as pollution, diseases, oil spills and a loss of kelp forests threatening the survival of this keystone species.
Ways you can help protect Sea Otters
More Marine Protected Areas
Support marine protected areas by going and visiting and seeing the otters in person. You are more likely to protect something if you know it’s there. It also supports the communities around it who earn their livelihoods by tourism or fishing around the MPAs.
Stand up for sea otters and sign petitions for new MPAs on the coastlines. These MPAs allow nature to recover from human impacts like fishing, which increases the productivity and diversity of the MPA. With healthy populations of species inside of MPAs, this can have a spillover effect into the surrounding waters. This benefits both local fishermen and sea otters. MPAs can also reduce the risk of sea otters being hit by boats and being caught in fishing nets. As the otter populations increase in MPAs so does the kelp forest which creates a win/win situation for our keystone species and the planet.
Donate to Charity
Support organisations that help protect MPAs which are vital to sea otter’s survival or donate directly to sea otter conservation efforts. Consider donating to the Sea Otter Foundation & Trust or you can symbolically adopt a sea otter with WWF.
Beavers
Beavers are amazing ecosystem engineers. They actively modify their environment, creating many diverse habitats for other animals. This keystone species is found in North America, Europe and Asia.
Beavers make dams to protect themselves from large predators like wolves and bears. The dams slow the flow of water, resulting in large deep pools behind them.
By slowing water down, dams force water to spread sideways, creating large wetland habitats. These dams also help increase the groundwater levels, which aids in flood control and water conservation during droughts. Also, the deep pools created by the dams hold and trap sediments, which are rich in nutrients. All this sediment creates fertile soil for aquatic plants to thrive in wetland habitats.
The benefits of beaver dams cascade down the food chain. The ponds purify the water which flows downstream from pollutants and sediment. The abundance of plant life attracts many invertebrate species, and slow water creates the ideal habitat for many fish species as this study has shown.
IUCN Red List Status and Threats
Thankfully, beavers are listed as Least concern on the IUCN Red List, which shows beavers have healthy and increasing populations. However, like sea otters, human activities are the biggest threat to beavers. Water pollution, habitat loss from draining of wetlands and illegal trapping and hunting are all threats to this keystone species.
Ways you can help protect Beavers
Living Alongside Beavers
It’s common knowledge that beavers can destroy trees. But if you share a habitat with beavers, learning to co-exist with this species can be mutually beneficial.
Protect Your Property
If you are worried about your trees, you can wrap them in wire mesh to deter chewing. Also, there are pond levellers and culvert protectors that can be installed to reduce human-beaver conflict.
Limit Runoff
Another way to help is to limit pesticide use and runoff into waterways. According to this study, beavers are sentinel species which means they are very sensitive to toxins in their habitat. They will react before an environmental issue occurs, like canaries in a coal mine. The dam’s beavers build can influence the rate at which toxins are stored and move around the freshwater ecosystem. Beaver’s sensitivity makes them vulnerable to excessive runoff which contains toxins.
Beavers can accumulate toxins like cadmium and mercury when exposed to these in their environment. Leading to effects like organ damage, behaviour changes and a decreased reproduction rate. Minimising pesticide use and reducing runoff benefits not only beavers but the entire freshwater ecosystem, regardless of where you live.
Donate to Charity
The Beaver Institute is a non-profit organisation whose main goal is to resolve human-beaver conflicts. They offer free resources to address problems like tree damage, blocked culverts and drains and flooding caused by beaver dams. Grants are also available to help with the cost of installing beaver-proof structures. Additionally, the Beaver Institute also does research and educational programs to allow a deeper understanding of beavers and to teach the public. Consider donating to The Beaver Institute or another non-profit organisation that supports peaceful coexistence with this keystone species.
Wolves
Grey wolves are a vital predator keystone species, which play an important role in maintaining many ecosystems. The Greater Yellowstone ecosystem is a prime example showing the impact of wolves on a large scale. In 1926 the last wolf was killed in Yellowstone. This resulted in the ecological collapse of the park. However, in 1995, 41 wolves were introduced back to the Yellowstone National Park. These top predators are found in North America, Europe and Asia.
Once wolves were reintroduced into Yellowstone, this triggered a trophic cascade. By preying on elk populations, wolves influenced their grazing patterns. With fewer elk in open areas, this allowed the recovery of forests and grasslands. This shift of wolves preying on elk benefited the entire ecosystem. Reduced elk browsing alongside rivers allowed for the regeneration of riverbanks, leading to increased stability, and reducing erosion. The stabilised banks led to a higher water quality as less sediment was being deposited. With more trees on the riverbanks, this provided more nesting sites for many bird species. The abundance of trees created more resources for beavers to build dams, leading to a higher abundance of fish species. High numbers of fish, saw the return of bears back to the water’s edge. Riverbanks became more stable because of tree roots holding the soil together. This influenced the course of the river, which promoted further ecological changes.
The protection of grey wolves in the United States is complex, with many ongoing discussions. The 2022 Endangered Species Act has granted federal protection to wolves in 48 states and Mexico, but there is an exception for the Northern Rocky Mountain population. Yellowstone National Park spans across Montana, Idaho and Wyoming and allows full protection of the wolves within the park boundaries. But once the wolves venture outside of the park they are vulnerable to hunting. These states manage wolf populations outside of the park by hunting and trapping programs based on specific plans and state laws.
ICUN Red List Status and Threats
The IUCN Red List classifies Grey Wolves as least concern due to their global population. However as mentioned previously, local populations in the US face varying levels of protection. The primary threat to grey wolves is human activity, especially hunting and trapping.
Ways you can help protect Wolves
Visit National Parks
National Parks offer many opportunities to learn and appreciate the natural world, including the vital role of wolves in a healthy ecosystem. By visiting national parks that protect wolves and allow you to observe wolves in their natural habitats, you can directly support wolf conservation efforts.
Donate to Charities
You can also consider donating to reputable organisations to support wolf conservation. The World Wildlife Fund and the California Wolf Centre are a few examples of groups working towards the recovery of wolf populations in natural habitats.
Elephants
The world is home to three majestic species of elephants: the African savannah elephant, the African forest elephant, and the Asian elephant. African savannah and forest elephants are found across 37 countries in Africa. The Asian elephant has been found in 13 countries in Asia.
All elephants are herbivores meaning they eat various parts of plants. They also like eating fruit which is called a frugivore. Frugivores play a vital role in ecosystems. As they feed on fruit, they then transport the fruit seeds great distances to disperse the seeds. Seeds have a hard seed coat which allows it to pass through the elephant’s digestive system. Elephants’ seed dispersal ability depends on how far the elephant moves, the travel time in the gut of the animal, environmental factors and the sex and personality of the animal according to this study.
The study also shows that the average dispersal distance was 5.3km and the max distance by an elephant was 101km. Males dispersed seeds further than females and elephants which explored more dispersed further. This means elephants are an especially important part of forest regeneration. As they move across the landscape, they introduce new species of plants to other areas, promoting diversity and abundance of plant species within the ecosystem.
A higher diversity and abundance of plant species is the foundation of a healthy ecosystem. Plants are the start of the food chain, providing food for many species. An abundance of insects, birds, mammals and fish species all follow an increase in plant diversity.
By promoting plant diversity, elephants play a massive role in reforesting Africa and Asia. Through the process of photosynthesis, trees can absorb carbon dioxide for growth. Trees can store up to 48 tonnes of carbon in their wood every year. Sadly, our planet loses around 80,000 acres of rainforest daily. Seed dispersal via elephants gives us a natural solution to reversing deforestation and creating more carbon sinks. This is where forests absorb more carbon than they release. This means that elephants along with many other frugivores are crucial allies in reforesting rainforests and therefore helping fight against climate change.
ICUN Red List Status and Threats
Elephants can only help the environment if we protect them. Humans are elephants’ biggest threat with African elephants being affected by poaching and Asian elephants being threatened by a decrease in habitat and human-wildlife conflicts. The decline in elephant numbers directly impacts seed dispersal, which affects those ecosystems. According to WWF every year 20,000 African elephants are killed for their tusks. On the ICUN red list, African Savanah Elephants are Endangered and the African Forest Elephants are Critically Endangered. The Asian Elephant is also listed as Endangered.
Ways you can protect Elephants
Say No to Ivory
Do not buy any products that contain ivory, such as trinkets, chess sets, piano keys, necklaces etc. The demand for ivory fuels the illegal poaching trade which decimates elephant populations.
Choose Sustainable Palm Oil
Look for products that use certified sustainable palm oil, like those endorsed by the RSPO (Roundtable on Sustainable Palm Oil). Palm oil plantations are a major driver of habitat loss for Asian elephants. Using certified sustainable palm oil products at home, allows you and other consumers to push producers to do the right thing by making their products certified sustainable.
Support Responsible Elephant Sanctuaries
When travelling, do your research before visiting elephant sanctuaries. Avoid going places where elephants are exploited and are forced to perform and/or are chained. Also, places where you can touch, ride, or bathe them and where there are young elephants. The World Animal Protection Guide is a good place to start, to know what to look out for when travelling.
Donate to Charities
Consider donating to charities that are dedicated to saving elephants and working on preventing poaching and habitat loss. Organisations such as the Sheldrick Wildlife Trust offer opportunities to donate and symbolically adopt an orphaned elephant, rhino, or giraffe. They work on many projects such as raising orphans, air surveillance, anti-poaching teams and many more.
The WWF also allows donations for general elephant conservation or to symbolically adopt an elephant.
Whales
Two main types of whales inhabit the world’s oceans: toothed whales, which include dolphins and killer whales, and baleen whales, which include blue and humpback whales. Toothed whales actively hunt for food like squid and fish. While baleen whales have a sieve-like structure in their mouth called a baleen to filter krill from the water. These ocean giants are migratory, travelling vast distances from the tropics to the polar zones.
Phytoplankton are microscopic marine plants that form the base of the ocean food chain (primary producers). Their growth depends on three main limiting nutrients: Nitrogen, Iron and Phosphorus. Iron is a very limited nutrient in the ocean, so it needs to be cycled around to benefit the growth of phytoplankton. Phytoplankton are found in the photic zone of the sea. This is the top part of the ocean which receives light from the sun. Through photosynthesis, phytoplankton create sugars for energy, which they use for growth and reproduction. This means that phytoplankton can remove carbon from the atmosphere, which helps our planet. The health of the entire ocean ecosystem depends on the abundance of phytoplankton.
Baleen Whales get iron from their diet of Krill (zooplankton) as krill eat iron-rich microscopic plants (phytoplankton). A common misconception, dispelled by this study is that whales compete with humans for fish. This is incorrect as the more whales there are the better the fisheries will be all over the world. Whales play a critical role in iron cycling, which promotes the growth of phytoplankton and ultimately supports a larger population of fish. Whales release their faeces at the surface (photic zone), which is where phytoplankton are in the water column. So, this cycling allows for the phytoplankton to use the iron that the whales have released, which creates the foundation of the marine food chain.
Another study shows the role of sperm whales in the Southern Ocean as carbon sinks, helping to remove greenhouse gases from the atmosphere. The sperm whale population defecate 50 tonnes of iron to the photic zone every year. This increases the amount of primary production carried out by phytoplankton, which leads to the transport of 400,000 tons of carbon to the deep ocean each year. This carbon becomes stored in the ocean sediments, potentially for millions of years. Unless disturbed by human activities such as oil and gas extraction, where the stored carbon is released back into the atmosphere as CO2. While sperm whales release some CO2 through respiration, they also increase primary production which sequesters carbon. So, they can effectively capture 200,000 tonnes of CO2 annually which is then stored in the deep ocean.
The findings from this study show the great contribution of whales to mitigating climate change. There are 13 species of great whales found in the world. So, imagine the amounts of carbon that can be sequestered if all of these keystone species have healthy populations.
ICUN Red List Status and Threats
The conservation status of whale species varies considerably. The ICUN red list stated that the Blue Whale and North Pacific Right Whale are endangered, while Sperm Whales and Fin Whales are vulnerable. Fortunately, Humpback Whale populations are of least concern and even increasing. The biggest threats to whales include commercial whaling, climate change, plastic pollution, noise pollution and ship strikes.
Threats to whales and how you can help them
IWC and Commercial whaling
The International Whaling Commission (IWC) is made up of 88 governments and was established to regulate whaling and promote whale conservation. The IWC regulates three types of whaling: commercial, scientific research and Aboriginal subsistence whaling.
In 1986 a temporary ban was put on commercial whaling by the IWC as whale numbers were decreasing. This ban is still in place but commercial whaling continues in Japan of Minke, Bryde’s and Sei whales. In Norway of Minke whales and Iceland of Minke and Fin whales.
The IWC is made up of 200 experts in whale biology. They discuss sustainable and precautionary catch limits of commercial and Aboriginal whaling, and they respond to questions about the conservation of whales.
Entanglement in fishing gear and Plastic Pollution
Whales are mammals so they must be able to breathe. Which means if they become entangled in fishing nets they can drown. In this study, 89% of the fishing gear that caused entanglements of Right and Humpback whales were pot and gill nets. But there was also a large variety of fishing gear seen.
Even after breaking free from fishing gear, whales can suffer lasting harm. This can come from dragging the gear which can cause fatigue, restrict movement, and increase the risks of further entanglement. Also, whales can suffer injuries like cuts which can become infected, haemorrhages and tissue damage.
The WWF estimates that 500,000 to 1 million tonnes of fishing gear are left in the ocean every year. Abandoned fishing nets are known as ghost nets, and they are incredibly deadly to all marine life. This is because fishing nets are made of nylon, which is a type of plastic, taking up to 600 years to break down. This means these ghost nets will continue to float around the ocean capturing anything in its path for centuries to come.
Solutions to Ghost Fishing
Some solutions to reduce ghost fishing are by educating fisheries and improving the disposal and recycling of nets. Also, by marking fishing gear so the owner can be identified and looking at creating more biodegradable nets that break down over time. While there is no international treaty that specifically targets ghost gear, we can urge governments to support the UN treaty on marine plastic pollution. This allows an opportunity to address global governance of ghost fishing gear.
Noise Pollution
Noise pollution from cargo ships and oil and gas exploration have negative effects on whales, as it disrupts their ability to use echolocation to find food and avoid predators. Unlike other threats which whales face, noise pollution is much easier to reduce or eliminate entirely.
This report examines three strategies to reduce noise pollution for whales which are impacted by cargo shipping: reducing vessel speeds to decrease emitted decibels, developing innovative technologies to reduce noise generation, and rerouting shipping lanes to avoid whale habitats.
Help reduce the impacts of ships on Whales.
The Ocean Wise Siting Network, a Canadian citizen science project, gathers data on sightings of 23 species of cetaceans (whales, dolphins, and porpoises) and sea turtles. They recently launched the Whale Report Alert System which directly informs commercial ships about nearby cetaceans, which helps reduce ship strikes.
Ways you can protect Whales
More Marine Protected Areas
Support petitions that fight against ocean pollution, fight for more marine reserves, 30 x 30 and conservation of whale keystone species and other marine life in your part of the world. New Zealand is home to Maui and Hector’s dolphins, which are the world’s smallest dolphin species. My dream is to see them in the wild, but sadly, their populations are very small. With only 48 to 64 Maui dolphins remaining, there are many local petitions which urge for protection against fishing gear entanglement and oil and gas exploration in their habitat by pushing for more marine mammal sanctuaries.
Beach Clean Ups
Even small actions can make a big difference. Participating in beach clean-ups or simply taking all your trash home after a day at the beach can significantly contribute to a cleaner ocean.
Whale Safe Boating
For whale-safe boating in New Zealand, Department of Conservation regulations recommend reducing speeds and maintaining a safe distance from whale pods.
Donate to Charity
Consider donating to charities such as WWF and symbolically adopt a Whale.
Thank You for Reading!
I hope you enjoyed learning about keystone species, why we need them and how you can make a difference! If there were any other keystone species you would like me to research and talk about, leave a comment below and I can do a Part 2. Let me know what you got from this post and how are you going to help these species going forward. Whether it’s changing one of your daily habits or donating to a charity to help these keystone species in the future e.g. Sheldrick Wildlife Trust.
Georgia xo
