You Won't Believe How Climate Change is Destroying Cariboo's Lakes – The Shocking Truth Revealed!

CARIBOO OUTDOORS: Climate Change and Lake Health

As I gazed at the low water levels in our local lakes last year, I found myself contemplating the impact of these conditions on lake health and the fisheries that depend on them. My curiosity led me to a scientific paper by Ken Ashley, Ph.D., R.P. Bio, titled “Predicted Impacts of Climate Change on BC Lakes,” published on January 25, 2024. As the discourse around climate change becomes increasingly polarized, the scientific community continues to gather evidence that underscores its seriousness, particularly concerning aquatic ecosystems.

While Dr. Ashley's paper touches on various issues, including potential hydroelectric impacts, I want to focus specifically on how climate change threatens our local lakes. Understanding the terminology is crucial here, especially when discussing lake turnover, which I explored in previous columns.

There are three primary types of lake turnover: dimictic, where a lake turns over twice a year (typical for smaller lakes), monomictic, where a lake mixes completely once a year, and meromictic, which refers to lakes that have distinct layers of water that do not intermix. The last two are particularly relevant to deeper lakes.

In our region, the smaller lakes that usually exhibit dimictic characteristics may shift towards becoming meromictic, leading to a failure in vertical mixing of water layers. This shift could result in significant temperature fluctuations. For instance, if a lake does not stratify as it typically would, it could exceed the maximum temperature of 25°C that trout can tolerate, posing a serious threat to fish populations. Additionally, the lack of oxygen in such lakes could lead to both summer and winter fish kills.

Evaporation of lake water also raises concerns about the concentration of dissolved minerals, which could affect the lakes' pH levels. The pH scale ranges from 1 (very acidic) to 14 (very alkaline), with 7 being neutral. Fish generally thrive in a pH range between 6.5 and 8.5. Alarmingly, lakes that become overly acidic (below a pH of 4.0) or too alkaline (above 9.0) will struggle to support aquatic life. For example, Green Lake typically has a pH level between 8.5 and 9.5, meaning that continued evaporation could push it further into the alkaline spectrum, becoming increasingly inhospitable for certain species.

Specific fish species exhibit particular pH preferences: Kokanee salmon flourish in a pH range between 6.5 and 8.5, while rainbow trout prefer a narrower band of 7.0 to 8.0. The implications are clear: as lakes like Green Lake face rising pH levels due to evaporation, local fisheries could see substantial declines.

For those interested in a quick visual assessment, acidic lakes often appear brackish and muddy with tannic stains, often featuring lily pads, while alkaline lakes tend to be much clearer with green-colored bottoms. This can serve as a general rule of thumb for assessing a lake's pH levels at a glance.

It's crucial to note that while changes in lake ecosystems will manifest over time, the shallower, nutrient-rich, and eutrophic lakes are likely to be the first to succumb to these alterations. Indeed, we have observed concerning phenomena, such as a summer fish kill at Earle Lake, emphasizing that the threat is not merely theoretical.

In conclusion, as we continue to witness the effects of climate change, it is imperative that we remain vigilant about the health of our lakes. The degradation of these ecosystems could have profound implications not only for local fisheries but also for the broader environmental health of the region. Understanding the scientific underpinnings of these changes is essential for fostering informed discussions about conservation and sustainability within our communities.