Regardless of how we got here, climate change is a global crisis that affects ecosystems worldwide. While much attention has been given to its impact on large bodies of water like oceans and rivers, it is essential to recognize the profound effects climate change will have on smaller ecosystems, such as small ponds and water gardens. These seemingly insignificant bodies of water are teeming with life and can provide critical habitats for a diverse range of species. Though somewhat gloomy, this post will explore how climate change is poised to disrupt the delicate balance of small ponds and how that change will imperil their inhabitants.
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Temperature Fluctuations: Climate change leads to rising temperatures globally, and small ponds are not immune to this warming trend. (Freshwater Biologists are also not immune - as us burly Northerners tend to sweat a lot). As temperatures rise, small ponds become more susceptible to extreme heat events and prolonged droughts. These fluctuations in temperature can have negative effects on the delicate ecosystem within a pond. Increased water temperatures can alter the growth patterns of algae, disrupt the life cycles of aquatic organisms, and even cause mass die-offs of fish and amphibians that are unable to adapt quickly enough. Small waterbodies are highly susceptible to temperature change. Ponds warm up (and cool down) quickly, this can be very stressful for the fish and other organisms that we care most about.
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Changes in Precipitation: Climate change also affects precipitation patterns, leading to more frequent and intense rainfall events and/or prolonged droughts in different regions. Both scenarios pose significant challenges for small ponds. Heavy rainfall can cause runoff and erosion, carrying pollutants and excess nutrients from surrounding areas into ponds. These large slugs of water can lead to harmful algal blooms and oxygen depletion. Conversely, extended droughts can cause ponds to shrink and water levels to drop precipitously. Long stretches of sunny weather is, however, very good for my farmer’s tan… For landscape ponds, this can lead to displacing organisms that rely on these habitats for breeding, feeding, and survival. For species that can’t move to another pond (i.e. fish), this concentrates them in an ever shrinking habitat that positively benefits no one. For watergardens and koi ponds, it forces us to artificially maintain water levels. This relates directly to temperature fluctuation as a smaller water volume heats up faster than when the pond is “full”.
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Altered Hydrological Cycles: Landscape ponds are interconnected with surrounding groundwater systems, and climate change disrupts these hydrological cycles. Rising temperatures and changes in precipitation patterns can affect the balance of water inputs and outputs in ponds. Reduced groundwater recharge during droughts can lower water levels in ponds, impacting the availability of essential resources for aquatic life. Additionally, increased evaporation rates due to higher temperatures can further exacerbate water scarcity, jeopardizing the existence of numerous species that depend on these water bodies. Reduced groundwater levels are a long-term consequence of a changing climate. It will not be just our ponds that lament the disappearing subterranean aquifers, all of us will shoulder this particular burden.
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Biodiversity Loss: Climate change-induced alterations in small ponds can lead to a loss of biodiversity. This is truly important, as I've stated many times in past posts, diversity = balance, and balance = low maintenance, beautiful ponds. Changes in water temperature, quality, and availability disrupt the delicate balance required for the survival of numerous plant and animal species. Amphibians, such as frogs and salamanders, are particularly vulnerable, as their life cycles rely on suitable breeding and hatching conditions in ponds. In turn, the decline in amphibian populations can have cascading effects on the larger food web, impacting predators (big fish), prey (lil fish & insects), and the overall ecological functioning of the ecosystem (water quality). Warming water generally leads to less diversity and an increase in undesirable species due to decreased dissolved oxygen levels. For us on the ground, this means less trout and dragonflies and more mosquitos, algae, and warm water fish species.
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Increased Invasive Species: Climate change can create favorable conditions for the establishment and spread of vile invasive species in small ponds. Rising temperatures and altered precipitation patterns provide a more hospitable environment for non-native species to thrive. Wherever there is a weakness in the pond ecosystem, an invasive can sneak in and take hold (Kind of like teenagers, they seem to just show up one day and wreck all my, er… everybody's fun). Invasive species can outcompete native species for resources, disrupt ecological processes, and negatively impact the overall biodiversity and stability of the pond ecosystem.
(I have some tips for controlling a few of these transgressing plant species in this article here: Common Invasive Pond Weeds…)
To mitigate these effects, we must be vigilant managers of the waterbodies under our care. All is not lost! Keep the faith and all will be forgiven!
Investing in a good aeration system or pond filter for water gardens while keeping a lookout for invasive species is more important than ever. Conserving, maintaining, and rehabbing your local habitat are vital practices in order to maintain a beautiful pond. Plus, keeping a great open water resource in your backyard will benefit all of the local wildlife. This good, clean water that you are keeping for its aesthetic beauty will function as an oasis in a landscape of degrading resources.
Be observant, note the small changes that can affect your aquatic critters, and take an active role as a steward of your increasingly valuable aquatic habitats. By recognizing the importance of these seemingly inconspicuous bodies of water, we can take steps to maintain and enhance their quality and the well-being of the ecosystems they support in the face of a changing planet.
