Lakes Part 4: Gloeotrichia

By Dylan Moesker

Over the last few weeks in this four part article series, we have been discussing a number of topics that all revolve around lakes. We have talked about phosphorus inputs and algae, trophic status of lakes, tea-stained lakes, and how it all relates to lakes in Muskoka. In this last and final article, I will explain to you what Gloeotrichia is, how it is formed, and what it means for our lakes.

So what is it? Gloeotrichia (glee-oh-trick’-ee-ah)  are small, fuzzy, green floating dots of blue-green algae that have been more frequently noticed in lakes throughout Muskoka, though it does not really act like most of the algae we have discussed.

As a brief recall, we know that phosphorus is the main contributor to plant growth in lakes. Furthermore, we know that excess levels of phosphorus are the main cause of algal blooms for most lakes in Muskoka during late summer, when oxygen levels deplete and phosphorus is released from the sediment. In an oligotrophic lake (like Skeleton Lake), algae is extremely unlikely to bloom due to the high oxygen levels and low phosphorus levels. This is where Gloeotrichia is able to shatter all rules regarding levels of phosphorus and algae. Let me explain.

Gloeotrichia are known to appear in lakes with good water clarity. Essentially, this means that they are more commonly found in very clear lakes that have low-phosphorus levels rather than a lake with high phosphorus levels. How is this possible after I just said that high levels of phosphorus are the main cause of algal blooms?

This blue-green algae is able to acquire phosphorus by a process called “over-wintering”. Basically what happens is it will remain on the lake bottom and slowly grow colonies on the sediment surface where phosphorus is naturally released in lakes. These colonies will absorb any phosphorus being released, even if it is just a small amount. When they are well developed, the algae will release off the sediment and float to the surface, where they will continue to multiply by exposure to sunlight.

During its release and rise to surface waters, this algae will carry phosphorus throughout the water column where it normally wouldn’t be found, creating a possible environment for more algae to develop. This is why it is important for us to reduce the amount of excess phosphorus runoff into our watersheds.

It is still unknown as to why our lakes are hosting these unusual types of algae, though climate change is likely a factor. Luckily, unlike many other types of algae, Gloeotrichia does not produce any toxins and is safe to swim in.

So, what does this all mean for our lakes? New types of algae and organisms found in lakes can be a scary thought. Ecosystems of all kinds are often able to bounce back from a number of stressors, but they are extremely sensitive to foreign or invasive species. We have seen the detrimental effect of the spiny water flea in our lakes and the way purple loosestrife can overrun large areas of natural vegetation. Our water is incredibly important in not only the aesthetics and recreation of Muskoka, but many people get their drinking water from lakes.

As I sum up this final article of this series, I hope everyone understands that we have resource that no one can afford to put in jeopardy, and it is a necessity for us to be conscious of what we put into our lakes. Let’s all work together in keeping the natural beauty of Muskoka as pristine as it can be.

Past articles are available in this blog under the Watershed Notes Articles category or under Past Articles in the Resources section.

Lakes Part 3: Why Are Some Lakes Tea-stained?

By Dylan Moesker

As we continue to learn more about the types of lakes found in Muskoka, tea-stained lakes still remain a misunderstood topic. These lakes are misunderstood since they are naturally darker in colour and often have a name like Tea, Black, Brandy or Dark Lake.

If you recall, we have been discussing the different trophic status of lakes and how phosphorus levels can affect this status. This week’s article will examine tea-stained lakes, what causes them, and how they are different.

Tea-stained lakes (also known as dystrophic lakes) are often shallow bodies of water with a large amount of wetland area in their watershed, which provides an increase in decaying matter. Much of the production in these lakes comes from bacteria.

Why are these lakes brown? Think of a wetland as a ‘tea bag’. Water running through the wetland washes out the tannins and the Dissolved Organic Carbon from the wetland plants.

Dissolved Organic Carbon is different than the previously discussed dissolved organic matter because it is broken down by a good type of bacteria rather than just through natural decomposition.

When organic carbon is abundant, it causes bacteria to become more phosphorus dependant. As this happens, bacteria will consume the available phosphorus before algae can develop often leading to a decreased accessibility of phosphorus to algae.

This is the reason why tea-coloured lakes are much less sensitive to phosphorus inputs than an oligotrophic lake. Higher levels of phosphorus may enter a tea-coloured lake and the bacteria will use it up before algae can, whereas if the same amount of phosphorus was put into an oligotrophic lake, the lack of bacteria would allow algae to feed on the phosphorus, creating the dreaded algal blooms.

Believe it or not, tea-coloured lakes are very similar to oligotrophic lakes in that they both have very low productivity (minimal plant growth), though visually, these two lakes are complete opposites. Oligotrohpic lakes are very deep and clear, having high oxygen levels and low organic matter whereas tea-coloured lakes are not nearly as deep or clear, having plenty of organic matter and a brownish tinge through the entire water column.

This is not to say that tea-coloured lakes are invincible to algae blooms. In the past, we have seen the green soupy mix of algae in some organic lakes, but they are generally much less sensitive and susceptible to algae blooms. Essentially, higher total phosphorus in a tea-coloured lake does not necessarily mean a higher occurrence of algal blooms.

Next week in the finale of this four part series, I will discuss the blue-green algae known as Gloeotrichia. This type of algae is becoming more common in Ontario, and seems to bend all the rules of how algal blooms are formed. For now, enjoy your summer and remember that summer isn’t half over, it has only half begun!

Past articles are available in this blog under the Watershed Notes Articles category or under Past Articles in the Resources section.

Lakes Part 2: Where Does Phosphorus Come From Within My Lake?

By Dylan Moesker

In last week’s article we discussed the trophic status of lakes in Muskoka, different sources of external phosphorus input into a lake, and how phosphorus has the ability to increase plant and algal blooms in lakes. This week’s article will follow that same path but focus on the process of internal loading (phosphorus sources from inside the lake) relating to the timing of algal blooms.

To understand the process of internal loading, we need to understand what happens to lakes in the summer. As lake water warms up, the lake begins to stratify. Cold water is more dense than warm water, causing the cooler water to settle at the bottom of the lake and warmer water on top. Oxygen is essentially trapped in both of these layers, and unable to move throughout the water column until the fall turnover.

As the unmixed bottom layer loses oxygen throughout the summer due to the decomposition of organic matter and uptake from fish, it triggers the release of phosphorus from the lake sediment into the water column – this is known as internal loading.

As phosphorus is released, it has the potential to create an additional source of nutrients for algae. The reason why we typically see algal blooms during late summer in eutrophic lakes (lakes with more than 20 µg/L of total phosphorus) is because the extra phosphorus released from sediments in a low oxygen environment adds to an already high level phosphorus lake. Essentially it fuels more growth in a highly productive lake.

On the contrary, oligotrophic lakes (lakes with under 10 µg/L of total phosphorus) are not nearly as sensitive to internal loading. This is because these lakes already have a low level of phosphorus, high dissolved oxygen, and lower amount of organic matter. Phosphorus input from internal loading is not likely to significantly increase the total phosphorus levels. In fact, due to the high dissolved oxygen and low organic matter, these lakes are less likely to even have internal loads in the first place.

Phosphorus that is released during this time will settle back into the sediment during the fall turnover as the water column is re-oxygenated.

In most lakes, internal loading is a completely natural process. As stated in last week’s article, when left undisturbed and in a natural state, a lake will find a healthy balance between nutrient input and life in the lake. The process has the potential to accelerate vegetative growth when combined with external inputs.

So what does this all mean? Well, phosphorus is a natural element necessary for aquatic plant growth, just like nitrogen is necessary for trees and plants on land. Algae develop naturally in many lakes and, unless large blooms are noticed, is not something to worry about.

Next week’s article will discuss tea-stained lakes. These lakes are actually quite different from the lakes that were discussed in this week and last week’s articles, and they are impacted in a completely different way. For now, enjoy the warm weather and make every summer moment count.

Past articles are available in this blog under the Watershed Notes Articles category or under Past Articles in the Resources section.

Lakes Part 1: What Kind of Lake do You Have?

By Dylan Moesker

In Muskoka, we are surrounded by pristine lakes that offer a huge variety of recreational opportunities. Some lakes are deep and clear while others are shallow and murky, and we classify these lakes into different trophic levels. The term “trophic” refers to the amount of nutrients or plant growth in a lake. This article is the first in a four part series where I will explain how and why lakes are classified, what can directly influence trophic states, and what it all means for our lakes.

To start, lakes are classified into different states by a simple measure of the total phosphorus (TP) in a lake. Phosphorus is the limiting nutrient in aquatic ecosystems and generally controls plant and algae growth in most lakes. It is a naturally occurring element that is released from rocks and sediment, and all living plants and animals. Left in a natural state each lake will find a healthy balance between nutrient input and life in the lake. Human inputs can upset that balance.

Things like septic system effluent, agricultural runoff, fertilizers, and cleaning agents also contain phosphorus and if not disposed of properly, can lead to higher levels of phosphorus in our lakes – changing the trophic status.

In Ontario, lakes with less than 10 µg/L (micrograms per litre or parts per billion) of total phosphorus are termed oligotrophic. This generally implies that the lake is very clear and deep with minimal aquatic plants and algal blooms, as well as high levels of dissolved oxygen. Lake Joseph and Skeleton Lake are good examples of oligotrophic lakes.

Lakes containing between 10 – 20 µg/L of total phosphorus are termed mesotrophic. These lakes have some aquatic vegetation and can support an array of fish species. Bass Lake in Gravenhurst and Halfway Lake in Bracebridge are good examples of mesotrophic lakes.

Lastly, lakes over 20 µg/L of total phosphorus are termed eutrophic. These lakes have large areas of aquatic vegetation and are often subject to algal blooms, thus having lower levels of oxygen.  Barron’s Lake in Georgian Bay is a good example of a eutrophic lake. This lake is surrounded by wetlands.

Different lakes offer different recreational opportunities. Oligotrophic lakes like Skeleton Lake offer beautiful boating, swimming, and snorkeling recreation. Mesotrophic lakes offer fantastic fishing opportunities as these lakes are able to support a wide variety of fish. Eutrophic lakes are often the home of a number of different waterfowl, creating a great environment for bird watching.

So why are we concerned with the state of each lake? Many lakes are very sensitive to phosphorus inputs, and as I stated before, our cultural activities are changing trophic states in many lakes. This is regarded as a direct cause for large algal blooms in some lakes. When large blooms die off and fall to the bottom of the lake, they begin to decompose. This decomposition uses up much of the oxygen in the lower half of the lake, leaving minimal oxygen for fish and other aquatic species. This lack of oxygen can be potentially fatal to a large number of fish.

It is important to realize that algae are a naturally occurring plant that is completely necessary in our ecosystems. They only become an issue when high levels of phosphorus feed and essentially fuel larger algal blooms.

In next week’s article I will discuss internal loading – a different form of phosphorus input into a lake. If you would like to know more about the lake you live on or near, take a look at the Muskoka Water Web website for the Lake Data Sheet for your lake. For now, the only thing I ask of you is to be conscious about what goes down your drain. I feel it’s safe to say that none of us would enjoy swimming in a soupy-green mixture of water and algae.

Past articles are available in this blog under the Watershed Notes Articles category or under Past Articles in the Resources section.

If you ‘Love Your Lake,’ look after it

Do you Love Your Lake? Do you love to sit on the shoreline and look out across the water and see the reflection of trees on the other side? What about swimming? Canoeing? Boating? fishing? Or simply just being at the lake?

We all share our love for Muskoka and we have a shared responsibility to look after it. Do you know what you can do to look after your part of the lake and make sure that your children can enjoy the lake as much as you do? Get your lake involved in the “Love Your Lake” program and find out.

One of the most sensitive habitats in Muskoka, the shoreline, is also one of the most sought after. Many people come to Muskoka to enjoy their little piece of the shoreline. However, we are not the only ones who make use of it.

Plants, microorganisms, insects, amphibians, birds and mammals can all be found within the first 10 to 15 metres of land surrounding our lakes and rivers. In fact, this area can be up to 500% more diverse than areas found upland. Healthy shorelines also protect the quality of our water so that we can use it for drinking and recreational activities such as swimming and paddling.

These plants and critters are important to the health of your lake. Plants reduce erosion and cool the water. Insects, amphibians and birds help maintain a natural balance.

So how can we protect the sensitive shoreline habitat found in Muskoka? With the “Love your Lake’ program!

In a nutshell, here’s what “Love Your Lake” is about. Trained technicians survey all the properties on a lake taking photographs of every waterfront property. Each property is then evaluated against a set of criteria of lake stewardship practices and each property owner receives a confidential report for their property.

This program is spearheaded by the Centre for Sustainable Watersheds (CSW) and the Canadian Wildlife Federation (CWF) with the assistance of five regional organizations and funding from the Ontario Trillium Foundation.

Love Your Lake is being delivered across the province in five regions, including Renfrew County, Eastern Ontario, Kawartha & Haliburton, Greater Sudbury, and Muskoka.

The intent of these assessments is to engage shoreline property owners in activities to protect their lake. The assessments will NOT be used for any regulatory purposes, and the information collected will not be shared on an individual property basis with anyone. The information collected is for the property owner only, in order to provide simple actions that can be taken to help protect the health of the lake.

The 2013 Muskoka Love Your Lake program is being carried out on Leonard Lake, Peninsula Lake and Fairy Lake. Program participants include Muskoka Watershed Council, The District Municipality of Muskoka, EcoMuskoka Conservation, University of Waterloo, Leonard Lake Stakeholders Association, Peninsula Lake Association, and Fairy Lake Association.

The participation of local lake associations is essential for conducting a successful program. If you are interested in having the Love Your Lake program carried out on your lake in the future and have a lake association willing to get involved and provide volunteers, please contact [email protected] to have your lake added to the list.

Past articles are available in this blog under the Watershed Notes Articles category or under Past Articles in the Resources section.