It’s been a short while since my last update. The main reason is that I’ve actually been away for most of the month of June. This post has some important information worth a review, I believe.
Last Treatment: The lake was last treated on June 10, 2021. This treatment was a chemical application designed to again “knock back” the growth of filamentous algae. In past treatments, such an event usually resulted in us seeing the “floating — mostly dead and decaying” algae sink below the surface and the significant reduction of the “below the surface — growing” algae. This time, something has changed.
Next Treatment: Charlie plans to conduct another chemical treatment for the FA within the next few weeks (he’s just waiting for the chemicals to arrive).
The New Monster: Southern Naiad
You might think you are beginning to see the presence of the dreaded Hydrilla in Lake Blue Heron. Fortunately for us, it’s not. What we have growing now is Southern Naiad. Here is a brief excerpt from another web site.
One of the more common submerged plants (in fresh water lakes) is southern naiad (Najas guadalupensis.) Southern naiad is a rooted native aquatic plant that grows from the bottom of the pond. It has thin leafy stems that frequently reach near the surface of the water. In clear ponds it can grow from depths of ten feet or more. This plant has slender branching stems and leaves that occur opposite of each other on the stems or that may be arranged in a whorl of three. For more — read here… https://www.mossyoak.com/our-obsession/blogs/conservation/southern-naiad-is-a-common-underwater-weed.
Here is a picture from my dock…
In the lower-left corner, you see our long-term nemisis — filamentous algae. This is the decaying version, that floats on the surface. The “growing” version is seen as bright green “blobs” or spheres beneath the surface. From my dock, the amount of surface algae is far less than what I am used to seeing 1 month after a treatment. However, it really did not diminish much after the June 10th treatment — which is unusual.
To the left and right of my shadow, below the surface of the very clear water, you can see the “new” monster — Southern Naiad. I quote “new” in that we have always had Southern Naiad. It’s just that it could not get a very good footing for growth because the Filamentous Algae “choked out” it’s ability to attach to the lake floor, hence restricting it’s growth.
There is GOOD NEWS!
In actuality, the presence of the Southern Naiad (SN) is good news in several ways…
First, it tends to stay below the surface of the water. If you check the picture again, you would think that there is some floating SN just next to the floating Filamentous Algae (FA). It’s actually below the surface — the water is just clear enough that it appears floating. So the presence of SN is generally NOT a visual eye-sore as is the FA.
Next, the presence and spread of SN is a strong indicator that we are winning the battle against FA! I say this for two reasons — first, I don’t see the underwater spheres of new FA growth. It may be there in parts of the lake, but I have never seen my area be clear of that new growth — this is good. Second, the amount of floating FA has not really increased since the last June 10th treatment, despite high temperatures and lower rain amounts. NOTE: the recent rain activity is actually helping to reduce the FA presence too. I know those of us on the western shore still see more than we’d like, but the winds do blow in our direction, so we will see accumulations even if there are small amounts of FA.
Also, SN is a GREAT nutrient “sink.” Meaning that it will take up a lot of excess nutrient, nutrients that normally would dramatically increase FA and the decaying surface version of FA.
As a nice side effect, fish, turtles, and birds LOVE SN. NOTHING likes FA. The density of the SN is far less than FA presents and small bait fish (the type larger fish and birds like to eat) flourish in an SN environment. The only negative from a “lake visitor” standpoint is that it can foul an electric motor if it has reached close to the surface and it does tend to catch fishing lurers.
Finally, SN can be managed more easily with “natural” treatment. What I mean by this is that carp DEVOUR SN — they love it as a meal. Presently, we do have carp in the lake, so one might ask “Why is it able to grow so much if we have carp?” The answer interestingly is that the larger a carp gets, the less food they require and they tend not to consume much.
The next natural response might seem to be “Let’s add carp!!!” Please understand that those who manage our lake water, plant, and wildlife quality (mainly Charlie Messing) have more than 3 decades of experience with this difficult balance. I have been in contact with Charlie and he fully understands this lake (and the other lakes) and has plans to change treatments when appropriate. His wisdom for the moment (and I agree with this) consists of the following thoughts…
- FA is being robbed of nutrients by the presence of SN and therefore beginning to decline in density and new growth. Adding carp at this time would be counter productive to trying to eliminate the floating FA.
- The homeowners who have allowed (and in some cases planted) lake-front plants to extend into the lake a few feet are greatly improving the situation as this plant life is also absorbing nutrients before it can reach the FA growth areas.
- Hopefully, lake-front owners are also reducing fertilization loads near the lake as well — every bit helps.
- When, and if, the SN begins to reach nuisance levels (creates a visual eyesore or impacts lake activities too much (boating and fishing), the introduction of carp will help quickly reduce the SN and can be supplemented by well known safe chemical treatment if necessary.
The main hope here is that the FA surface presence will begin to abate more naturally as we work to keep the lake water nutrient load in check.
I have one additional thought. If the surface FA remains constant or even only slightly decreases, I would be inclined to see if there could be a way to skim it off the surface. This would only make sense to do if I’m correct about there not being much sub-surface FA remaining. Otherwise, we will just have to keep applying the chemicals through the summer months and continue to push back new FA growth.
I am optimistic, but still watchful — this is a DIFFICULT process for anyone to manage in a lake like Lake Blue Heron. I have said this before and will say it again — it took decades for this lake to see the nutrient load build up (not helped by the 2008ish lake draining events). Solving the problem of eyesore weeds will take some time. We must be prepared for the presence of FA until we find a balance that keeps its growth in check — and that balance is difficult. I suspect we are still a few years away from a time when we might consider a “Win” — but I do feel we are scoring a lot!
Fred Schmidt