Course:CONS200/2023WT2/Climate change impacts on prey-predator dynamics: What do we know so far?

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Climate change profoundly influences predator-prey interactions, shaping ecosystems worldwide. Direct effects like temperature rise and shifting population distribution, alongside indirect impacts such as habitat and food availability changes, alter the stability, abundance, and behaviour of predators and prey. Identifying these effects is challenging due to their complexity. Nonetheless, documented changes offer insight. Many species exhibit changes in their historical ranges, migration times, spawning seasons, and desired prey due to measured global temperature increases as well as other effects of climate change. Climate change directly refers to a long-term shift in the area's average temperature along with the potential for larger-scale shifts in weather patterns. These disrupt seasonal processes, affecting the behaviour and habitat use of many species, which can trigger cascading effects throughout the food chain. Over time, this results in an overall loss of global biodiversity, which leads to the degradation of biomes and other smaller habitats. Studies show that blooms in prey populations coupled with increasing predator density and decreased ingestion efficiencies due to climate change have led to predator starvation in some cases, impacting entire ecosystems. The future implications of climate change on predator-prey dynamics are uncertain but ominous. Mitigation strategies, including reducing greenhouse gas emissions and promoting sustainable practices, offer avenues to lessen these impacts. By addressing climate change, we can mitigate its effects on predator-prey interactions and safeguard ecosystems for future generations.

The Impact of Climate Change on Predator-Prey Species

The potential effects of temperature changes on predator–prey interactions based on a scenario of future global warming.

Climate change exerts profound influences on the intricate web of interactions between prey and predator species, reshaping ecosystems globally. Unfortunately, understanding the multifaceted effects is a difficult task to carry out with certainty due to the many confounding variables at play in natural ecosystems [1]. To account for this, the influence of climate change can be broken down into both direct and indirect consequences, exploring the specific effects of alterations in temperature, behaviour, distribution, habitat and food availability.

Direct Effects:

Direct effects refer to the immediate and observable consequences of climate change on species, such as alterations in temperature, changes in behaviour, and changes in distribution. These effects directly influence the physiology, behaviour, and abundance of prey and predator species.

Temperature Alterations:

Alterations in temperature can profoundly influence the phenology of both prey and predators. This direct effect refers to the immediate impact of changing temperature on the life cycles and behaviours of species. Different species may respond to temperature changes at different rates, causing a lack of synchrony in their interactions. It may also alter the timing of numerous seasonally dependent ecological processes, such as migratory patterns and seasonal habitat use.[2] This mismatch disrupts established relationships, potentially resulting in cascading effects on the entire food chain as discussed later in “indirect effects”. Temperature is also linked to an increase in the biomass of bacteria and bacterivorous consumers, creating a bloom in some prey species tied with decreased ingestion efficiency which disproportionately affects species of a higher trophic level. This can cause larger predators and herbivores to become extinct while the biomass of producers increases.[3]

Behavioural Changes:

Climate change induces direct alterations in predator and prey behavioural patterns. This is especially evident when examining how changes in habitat as a result of climate change create additional vulnerabilities or resistances in the prey population based on predator hunting tactics. For example, ambush predators are negatively affected by decreased vegetation density, whereas active predators who hunt prey over great distances, such as hyenas, experience the inverse effect.[4] Additionally, as prey and predator species shift ranges and adapt to their new conditions, they simultaneously influence each other’s morphology and behaviour. Where molluscs find new habitat as a result of rising sea levels and temperatures, native crabs are observed to quickly adapt new hunting behaviours as well as stronger and larger claws. This introduces a phenological arms race wherein phenotypical plasticity becomes a major factor in stabilising population sizes and establishing species co-existence or lack thereof.[5]

Distributional Changes

As climate change alters ecosystems, it can lead to changes in the distribution of both predator and prey species. For example, rising temperatures may cause certain prey species to move to higher latitudes or elevations where temperatures are cooler, or to shift their ranges to track changes in vegetation or food availability. Polar bears in the western Hudson Bay exhibit changes in their historic range across sea ice as a result of changes to the timing and rate of sea ice break-up and formation. This results in less access to high-energy food sources and leads to reductions in body condition, reproductive success, and therefore overall population numbers[2]. Other climate-change-related conditions, such as temperature increase and water hypoxia, allow for certain predator species to expand their historic range to take advantage of now vulnerable prey species, interrupting existing dynamics by opening them up to new sources of predation.[6]

Indirect Effects:

Indirect effects involve a chain of consequences triggered by the primary impacts of climate change. These may include shifts in habitat and food availability, alterations in season rhythms such as migration patterns, and changes in the overall ecosystem structure. Indirect effects are often more complex to trace than direct effects, as they result from the interplay of various factors influenced by the direct impacts of climate change.

Changes in Habitat and Food Availability:

Climate-induced changes in environmental conditions, such as warming, desalination, etc. impact prey properties which indirectly alters predator-prey interactions. Prey in poorer conditions because of habitat degradation are significantly more vulnerable to predation.[4] These modifications can lead to disruptions in established ecological processes, affecting feeding ecology and, consequently, overall ecosystem structure. Habitat fragmentation and climate variability create instability in the equilibrium states of predator-prey interactions[7] resulting in forced adaptation to a new non-equilibrium state or species extinction.

Altered Seasonal Rhythms:

Seasonal rhythms, which determine the timing of specific life events, are often closely coordinated between predators and their prey in order to optimise feeding periods. The effects of climate change, especially rising temperatures, have the tendency to disrupt these rhythms, creating asynchronies between predator and prey populations and thus altering feeding patterns and migration timing and reducing overall population stability. This asynchrony is well documented now between early plant leaf and the hatching time of primary consumers due to phenological shifts or changing abiotic environments[1]. This negatively affects the feeding ability of primary consumers, which in turn negatively affects the species that prey upon the consumers. Rising sea temperatures also affect the seasonal rhythms of many predator species including the arctic narwhal, reducing the species’ hunting range and thus disrupting their predatory interactions in Southern regions where they used to hunt.[8]

Additional Indirect Effects:

Beyond habitat, food availability, and seasonal rhythms, there are a vast number of small contributing indirect effects that deserve recognition. The vast diversity of species on the planet lends itself to an even more vast array of specialised interactions between predators and prey that each hinge upon various factors that are by no means equal amongst all groups. In this way, the combined potential that indirect effects of climate change have on the intricate and interconnected interactions between predator and prey species is as varied as the species interactions themselves.

Consequences of Climate Change on Species:

The consequences of climate change on prey and predator species are intricate, involving both direct and indirect influences. Temperature, alterations in behaviour, distribution, habitat, and food availability collectively shape the dynamics of ecosystems. Changes to these dynamics represent disturbances due to habitat fragmentation, stochasticity, and climate variability which creates systemic instability. New, non-equilibrium systems may have no or revised equilibrium states that drastically alter predator-prey dynamics. Evidence indicates that species ultimately have three choices: adapt, migrate, or die.[7]

History of the Effects of Climate Change on Predator-Prey Interactions

Historically, the majority of research on predator-prey dynamics has been measured with respect to the relationship's integrity as a continuous cycle.[2] The measure of integrity in these relationships is dependent on the trophic web the species adheres to.[2] Where there has been a decrease in predation and, conversely, an increase in prey numbers, problems often arise regarding the ability of predators to consume larger amounts of prey. One might assume that such an increase in prey would have historically aided the predator population, yet the findings repeatedly indicate an inverse effect.[3] With the consideration of climate as found in the Global Change Biology study, predator populations even lost some of their physiological ability to digest food properly during extreme climatic changes, leading to predator population starvation.[3] This example is indicative of climate related trends for predatory species, leading to booms in smaller prey life and effectively initiating extreme population losses in the predators.

The intensity of these predator/prey dynamic issues extends beyond simply direct impacts. Another historical example of altered predator-prey dynamics is illustrated in polar bear land and ocean dynamic access and its impacts on food security. With a decrease in ocean access comes a minimization of their land security; as such, many of their prey have boomed due to a new lack of predation. Where these bears do not have land or home security, they cannot spend the same amount or manner of time hunting for calorie-dense marine-based food. Leaving them in an altered predator-prey dynamic with respect to the majority of their food/prey.[2] While there is minimal research that specifically centers around climate change and predator-prey interactions, quite a bit more work is beginning to be done on these subjects. However, even with minimal access to research, clear trends appear between increases in climatic conditions and decreases in predator-prey dynamic security.

Forecasted Long-Term Effects of Climate Change on Predator-Prey Dynamics

In recent years, the pressing issue of climate change has resulted in significant effects on predator-prey interactions.[3] These changes, which are influenced by both direct and indirect factors, ultimately lead to population instability, altered migration patterns, and changes in predator behaviour.[3] As the issue of climate change rapidly worsens, it is important to predict the long-term consequences of these effects, how they might be exacerbated with the increasing severity of climate change, and if we may expect to observe new effects on these interactions in the future as the impact of climate change increases.

A significant threat that climate change poses to future ecosystems is its potential to cause biodiversity loss or even the extinction of certain species due to the rise of the Earth's temperature.[3] Research has found that as environmental temperature increases, predator ingestion efficiency generally weakens.[3] This means that more predators are becoming unable to consume food efficiently enough to balance their metabolic demands and energy needs. If warming continues its current rate, decreased predator ingestion efficiencies will eventually lead to the starvation of many of these predators. This would weaken predator-prey interactions to a detrimental degree that could result in the extinction of various species, causing a significant, long-lasting decline in the planet’s biodiversity.[3]

The extinction of species due to weakened predator-prey interactions, as discussed above, will not only have damaging consequences for the planet’s biodiversity, but may also cause a chain reaction in the way biotic species interact, resulting in long-lasting impacts on food chains and ecosystems. Research suggests that changes in our climate and land use may impact the abundance or prevalence of herbivores due to food scarcity.[9] The problem with this is not only that herbivore populations will be affected, but that the scarcity of herbivores will result in a domino effect that could impact carnivorous and omnivorous species due to their reliance on herbivores for food.[10] In turn, this increased demand for herbivores will cause increased predation pressure that may further limit the growth of herbivore populations. This predation pressure may then trigger other indirect interactions that can affect food webs and entire ecosystems, resulting in a trophic cascade.[10]

It is important to recognize that while there has been an increase in research on the effects of climate change on predator-prey dynamics due to the rapidly rising severity of climate change, there remains a lot of uncertainty when attempting to predict future long-term effects based on current and past trends. This is due to the complexity of these relationships and uncertainty regarding what we can expect to occur under extreme, future environmental conditions.[11] To mitigate the weakening of predator-prey interactions which may have detrimental effects on biotic communities and entire ecosystems, we must address the effects of climate change that are causing these worsening changes.

What Can be Done to Mitigate the Impacts of Climate Change on Predator-Prey Dynamics

Global greenhouse gas emissions as implied by INDCs compared to no-policy baseline, current-policy, and 2 °C scenarios.

To prevent the worsening of predator-prey interactions in food chains due to climate change, we must reduce its effects. Climate change is a complex issue that requires collective efforts to mitigate. One of the most well-known international contribution initiatives is the Paris Agreement under the United Nations Framework Convention on Climate Change (UNFCCC). It aims to limit global warming to below 2 degrees Celsius, with efforts to reach 1.5 degrees Celsius. Each participating country submits a Nationally Determined Contribution (NDC) outlining its strategies to achieve this goal. Many nations, including Canada and Egypt, have developed comprehensive climate policies and action plans to reduce greenhouse gas emissions, promote renewable energy, and increase energy efficiency. These countries provide and prove the many ways climate change can be mitigated, as “targets and actions for reducing greenhouse gas (GHG) emissions are core components.”[12]

Canada's NDC, accessible through the United Nations Climate Change website, highlights initiatives such as the Pan-Canadian Framework on Clean Growth and Climate Change to reach the 2030 target of reducing greenhouse gas emissions and becoming a low-carbon economy. The Pan-Canadian Framework on Clean Growth and Climate Change (PCF) is a national climate policy developed by the Canadian federal government in collaboration with provinces, territories, and Indigenous peoples to address climate change and promote sustainable economic growth, focusing on carbon pricing, clean energy, transportation, and adaptation measures.[13] For example, PCF works to increase renewable and non-emitting energy sources by accelerating “the phase-out of traditional coal units across Canada” by “invest[ing] in, and increase[ing] the use of clean electricity across Canada, including through additional investments in research, development, and demonstration activities.”[14]

Another example is Egypt's NDC, accessible through the United Nations Climate Change website, the contribution of Green Finance to fund eco-friendly projects, including Sovereign Green Bonds. Additionally, Egypt identified various green projects totalling $1.9 billion. Those projects focus on renewable energy, clean transportation, sustainable water management, and pollution reduction.[15] Green Finance is vital to reducing global warming; it “mainly promotes the flow of financial instruments towards the development of sustainable business projects, social investment, social trade and environmental policies.”[16]

For The United States of America’s NDC, also accessible through the United Nations Climate Change website, the focus will be on their contribution to reducing emissions from forests and agriculture and enhancing carbon sinks. The NDC states that The United States will do so by making plans to promote climate-smart agricultural practices like reforestation, rotational grazing, and nutrient management. It will also invest in forest protection, management, and wildfire prevention, aiming to reduce the severity of wildfires and restore fire-damaged forest areas.[17].

Lastly, another way to reduce the effects of climate change includes private conservation initiatives. An example is non-governmental organizations (NGOs) such as The Nature Conservancy (TNC). On their website, the “What we do” section states that their goal is to stop the severe effects of climate change and the loss of biodiversity. They plan to reach that goal by using “the power of nature and the strength of policy and markets to reduce emissions, support renewable energy and store carbon.”[18] TNC implements Natural Climate Solutions (NCS) to protect, manage, and restore nature. NCS refers to strategies and actions that utilize nature-based approaches to mitigate climate change by removing greenhouse gases from the atmosphere or reducing emissions. In their “Natural climate solutions” section, they state it includes practices such as: “improving forest management to help forest owners increase the carbon stored in their trees; reducing fertilizer use for fewer greenhouse gas emissions; restoring coastal wetlands to sequester carbon in submerged soil.”[19]

Conclusion

To conclude, climate change profoundly impacts predator-prey interactions, affecting ecosystems globally. These effects are both direct and indirect. Direct effects, such as temperature increases, sea level rise, and shifting populations, directly influence the physiology and abundance of species. Similarly, indirect impacts, like shifts in habitat and food availability, and alterations in migration patterns, disrupt the stability and behavior of predators and prey. Continued global warming and habitat transformations pose significant challenges to species' adaptability, potentially leading to irreversible damage to ecosystems in the future.

These complex disruptions can cause cascading effects throughout food chains, leading to predator starvation and impacting entire ecosystems. Despite the complexity of these interactions, evidence from historical records and recent studies highlights shifts in species ranges, migration timing, and feeding habits, providing insight into the extent of the problem and emphasizing the necessity of addressing climate change.

Mitigation strategies offer ways to lessen the impact of climate change on predator-prey interactions and protect ecosystems for the future. International collaborations like the Paris Agreement provide a framework for collective action to limit global warming and reduce greenhouse gas emissions. Countries must implement functional and everlasting climate policies and sustainable practices to promote resilience and mitigate environmental degradation.

Private conservation initiatives also play a crucial role in ecosystem preservation by promoting emissions reduction, renewable energy adoption, and nature-based solutions. These actions are crucial for protecting ecosystems and ensuring the long-term viability of predator-prey interactions.

It is important to realize that although the future of our planet is uncertain, we can help create a better future by making concerted efforts at local, national, and international levels to challenge climate change.

References

  1. ↑ 1.0 1.1 Damien, Maxime; Tougeron, Kevin (2019). "Prey–predator phenological mismatch under climate change". Current Opinion in Insect Science, 35, 60–68.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 Cherry, Seth G.; Derocher, Andrew; Thiemann, Gregory W.; Lunn, Nicholas J. (2013). "Migration phenology and seasonal fidelity of an Arctic Marine Predator in relation to sea ice dynamics". Journal of Animal Ecology, 82(4), 912–921.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 Rall, Bjorn C.; Vucic-Pestic, Olivera; Ehnes, Roswitha B.; Emmerson, Mark; Brose, Ulrich (2010). "Temperature, predator-prey interaction strength and population stability". Global Change Biology, 16(8), 2145-2157.
  4. ↑ 4.0 4.1 Morin, Aïssa; Chamaille-Jammes, Simon; Valeix, Marion (2021). "Climate Effects on Prey Vulnerability Modify Expectations of Predator Responses to Short- and Long-Term Climate Fluctuations‌". Frontiers in Ecology and Evolution.
  5. ↑ Kossak, Ute (2006). "How climate change translates into ecological change: Impacts of warming and desalination on prey properties and predator-prey interactions in the Baltic Sea" (PDF). Mathematisch-Naturwissenschaftlichen Fakultaet, Christian-Albrechts-Universitaet, Kiel (FRG).
  6. ↑ Domenici, Paolo; Allan, Bridie J M; Lefrancois, Christel; McCormick, Mark I (2019). "The effect of climate change on the escape kinematics and performance of fishes: implications for future predator–prey interactions". Conservation Physiology, 7(1), coz078.
  7. ↑ 7.0 7.1 Arumugam, Ramesh; Guichard, Frederic; Lutscher, Frithjof (2020). "Persistence and Extinction Dynamics Driven by the Rate of Environmental Change in a Predator-Prey Metcommunity". Theoretical Ecology 13.
  8. ↑ Chambault, P.; Tervo, O. M.; Garde, E.; Hansen, R.G.; Blackwell, S. B.; Williams, T.M.; Dietz, R.; Albertsen, C. M.; Laidre, K. L.; Nielsen, N. H.; Richard, P.; Sinding, M. H. S.; Schmidt, H. C.; Heide-Jørgensen, M. P. (2020). "The impact of rising sea temperatures on an Arctic top predator, the narwhal". Scientific Reports, 10(1).
  9. ↑ Labadie, Guillemette; Hardy, Clément; Boulanger, Yan; Vanlandeghem, Virginie; Hebblewhite, Mark; Fortin, Daniel (2023). "Global change risks a threatened species due to alteration of predator–prey dynamics". Ecosphere (Washington, D.C), 14(3).
  10. ↑ 10.0 10.1 Cite error: Invalid <ref> tag; no text was provided for refs named “:5”
  11. ↑ Logan, J. David (2008). "Phenologically-Structured Predator-Prey Dynamics with Temperature Dependence". Bulletin of Mathematical Biology, 70(1), 1-20.
  12. ↑ Rogelj, Joeri; den Elzen, Michel; Höhne, Niklas; Fransen, Taryn; Fekete, Hanna; Winkler, Harald; Schaeffer, Roberto; Sha, Fu; Riahi, Keywan; Meinshausen, Malte (2016). "Paris Agreement climate proposals need a boost to keep warming well below 2 °C". Nature, vol. 534, no. 7609, pp. 631–639.
  13. ↑ "CANADA'S 2021 NATIONALLY DETERMINED CONTRIBUTION UNDER THE PARIS AGREEMENT" (PDF). Government of Canada. 2020. Retrieved April 14, 2024. line feed character in |title= at position 49 (help)
  14. ↑ "Complementary actions to reduce emissions". Government of Canada. 2016. Retrieved April 14, 2024. the phase-out of traditional coal units across Canada” by “invest[ing] in, and increase[ing] the use of clean electricity across Canada, including through additional investments in research, development, and demonstration activities.
  15. ↑ "Egypt's Second Updated Nationally Determined Contributions" (PDF). United Nations Framework Convention on Climate Change. 2023. Retrieved April 14, 2024.
  16. ↑ Elsherif, Marwa (2023). "Green Financing as a Tool to Mitigate Climate Change for Sustainable Development: An Insight form Egypt". International Journal of Economics and Financial Issues, vol. 13, no. 3, 14 May 2023, pp. 33–45.
  17. ↑ "The United States of America Nationally Determined Contribution Reducing Greenhouse Gases in the United States: A 2030 Emissions Target" (PDF). Government of the United States of America. United Nations Framework Convention on Climate Change. 2021. Retrieved April 14, 2024. line feed character in |title= at position 29 (help)
  18. ↑ "Tackling Climate Change". The Nature Conservancy. Retrieved April 14, 2024. the power of nature and the strength of policy and markets to reduce emissions, support renewable energy and store carbon.
  19. ↑ "Natural Climate Solutions". The Nature Conservancy. Retrieved April 14, 2024. improving forest management to help forest owners increase the carbon stored in their trees; reducing fertilizer use for fewer greenhouse gas emissions; restoring coastal wetlands to sequester carbon in submerged soil.


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