Ephemeral Ponds

Ephemeral ponds may not look like much more than a seasonal puddle, but they are extremely important to our local ecosystem. Thousands of young amphibians hatch in these ponds each spring and spend the first portion of their lives developing in them before moving to the forest. Some of these creatures are at risk of extinction! Ephemeral ponds vary greatly in size depending on the area and amount of rainfall and can be many acres in diameter or not much more than a large puddle, but in general, are shallow and no more than a meter deep. In PKOLS – Mount Douglas, you may notice a large puddle where there wasn’t one before, and in a few months, it’s gone. These puddles are full of life, some of which are at risk of extinction. These temporary ponds that typically show up in spring and disappear in summer are called ephemeral ponds. In Victoria where there is heavier rainfall instead of snow in the winter months, these ponds will appear in the fall. Surprisingly they are considered to be wetlands even if they are dry most of the year.

Ephemeral pond in PKOLS – Mt. Douglas

When rainfall increases, water collects in shallow depressions in the earth and creates an ephemeral pond. Ephemeral ponds are extremely important to their local ecosystems and greatly benefit the environment. Not only do they support a wide variety of life, but they also act as natural filters, purifying water through the soil before it returns to a larger source. Like a sponge, ephemeral ponds absorb and store a lot of water in the soil, and this ability can reduce flooding, buffer against drought and help regulate the temperature of the surrounding area.

Ephemeral ponds provide seasonal breeding grounds used by many amphibians, reptiles, and insects. Some creatures rely on ephemeral ponds exclusively to breed and will migrate to the same pond each spring to lay eggs. In Saanich, a few species that can be found in ephemeral ponds are the Northwestern salamander, red-backed salamander, long-toed salamander, rough skinned newt, pacific tree frog, and Northern red-legged frog.

Long toed salamander – PKOLS – Mt. Douglas

Being temporary and shallow, ephemeral ponds inhibit the establishment of fish, creating an ideal habitat for frogs and salamanders. Fish not only eat these creatures and their young but also compete with them for food by consuming insects. Even without the threat of fish, amphibians still need to be on guard because these ponds are also an important stop for some migratory birds who may see them as a snack. As an ephemeral pond becomes more established it attracts other animals as well including turtles, snakes, and raccoons.

In the spring, breeding frogs and salamanders deposit jelly-like masses of eggs in ephemeral ponds. As thousands of amphibians hatch they feed on a variety of insects that are hatching at the same time, such as dragonflies and mosquitos. Young amphibians will remain in the ephemeral ponds until fully developed before making their way into the forest to continue their adult life.

The Fragility of the Small creatures

Globally, amphibians are the most threatened group of vertebrates, with roughly 32% at risk. In B.C. approximately 44% of salamanders and 64% of frogs are at risk, with human interference largely to blame. Invasive species, global warming, habitat loss, pollutants, and letting pets and children play in ephemeral ponds all play a role in the amphibian population decline.

Red backed salamander – PKOLS – Mt. Douglas

Amphibians have extremely permeable skin used to transfer nutrients, oxygen, carbon dioxide and water between the environment and the amphibian’s body. This puts them at a much higher risk of being impacted by contaminants like pesticides that run off into their environment. Even things considered to be natural like dog droppings, fertilizer, compost and yard waste can introduce harmful bacteria, bring about infectious disease, and cause large algae blooms which use up essential oxygen in ponds. When amphibians are under stress in non-ideal conditions, their immune systems weaken putting them at an even higher risk of mortality.

Global warming greatly impacts amphibians because they are dependent on weather for breeding behaviour. They may wake from hibernation too early because of warm temperatures and lay eggs, then climate extremes may cause late-season freezing, killing the eggs and young. Rising temperatures may also dry up ephemeral ponds before the tadpoles have sufficient time to develop. At this phase in life tadpoles cannot live outside of water and will die. Increasing temperatures also interfere with amphibian’s ability to regulate their internal body temperature via water evaporation through their permeable skin. If it is too hot and dry, they face a risk of dehydration and are at risk of overheating.

Habitat loss from drainage or diversion of these ponds for urban development and agriculture is also a huge threat. Many amphibians cannot reproduce on dry land as their eggs are jelly-like and their young require water to develop. If they lose their habitat they will be forced to find a new home which means they face the additional risk of travel-related death from crossing roads.

Allowing dogs and children to play in these ponds is also an issue. Natural areas all over are faced with the challenge of finding a balance between nature, humans, and their 4 legged friends; especially with increased traffic since Covid. While most people don’t see the harm in letting their playful pooch or curious kids splash around in ephemeral ponds, it actually does quite a bit of damage to these ecosystems. Many sensitive creatures and their delicate eggs and young are living in ephemeral ponds; some may be lying dormant underground in the winter months. Tromping around in ephemeral ponds increases the risk of them being crushed.

Protecting Ephemeral Ponds

Ephemeral ponds are often overlooked, and being so essential to many woodland species it is extremely important to recognize and protect them. Tampering with ephemeral ponds in any way can be detrimental to the inhabitants. Even seamlessly harmless activities can have a negative impact.

So how do you protect something you can’t see most of the year? When identifying ephemeral ponds in the dry season look for areas of blackened and compressed leaf litter, watermarks on surrounding tree Red-backed salamander – PKOLS – Mt. Douglas trunks, and patches of grey soil. Generally, there will be moisture tolerant vegetation in the area as well, similar to what you would see along the edge of a creek or lake.

Protecting the forest surrounding ephemeral ponds is important as amphibians enjoy a cool moist environment, and abundant hiding places. Having a healthy canopy of trees provides a necessary source of shade and shelter. It also slows the pond from drying up, giving young amphibians enough time to fully develop.

It’s a good idea to have a riparian buffer zone between the pond and any activity that could potentially contaminate or degrade the water quality. Ephemeral ponds accumulate water runoff from surrounding areas, and even small amounts of contaminants can have deadly consequences. A buffer zone also blocks excess sediment from blowing in which can fill the bottom of ponds, suffocating eggs and reducing water quality.

Adding and removing debris from the pond can also be harmful to its inhabitants. Adding woody debris, which we might think is helpful, could cause excess nutrients to leach into the pond causing algae blooms and reducing water quality. Removal of debris should also be avoided as this may kill existing eggs that are attached to them, or disturb juveniles using the debris for shelter.

Healthy ephemeral pond in PKOLS – Mt. Douglas

On a larger scale in any populated areas, the consideration of fencing off ephemeral ponds should be taken to protect them year-round. It is extremely important that they remain undisturbed, even during the dry season when they appear to be empty. Foot, pet and vehicle traffic will compact the soil and result in water flow change. Irregular ruts in these ponds may lead to early drainage which is deadly to amphibians that have not yet hatched or matured. Walking through these areas will also harm dormant eggs and larvae that are buried beneath the leaf litter.

If everyone does a little, it will amount to a lot.