Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations Bluegill spawning and filamentous algae

I currently have big mats of ugly thick filamentous algae extending from the shore out 8' to 20' into my lake. The mats are the biggest and thickest in all my shallow coves. These same gravel bottom coves are where I have seen most of my bluegill spawning over the years. My question is does the big floating mats of filamentous algae prevent my bluegill from spawning on the shallow gravel beds? The stuff is thick! In the last few days we have been using a rake to pull it ashore. The lake is 100 acres - so there is only so much we can pull ashore. The algae has in the last 2 weeks floated and still is attached to a lot of my hard wood in the shallows down to 5'. I also note that I find 1" fingerling bass spawn stuck in the algae. This is the first year we have ever had such a crop of this scum algae so I am concerned it will impact our bluegill spawn.

Thanks!

Dave

P.S. - I am planting 500 lbs. of 3/4 - 1 lb. Mozambique tilapia in the lake this week. Will tilapia eat up these thick mats?

Dave

It has to have an effect. One of the criteria for nesting is sunlight. However, I expect nature will overcome the problem. The BG's will either find another place or another opportunity. There are documented cases in Texas lakes of bass nesting in the forks of standing timber.

I expect the baby bass would have been Ok had you not raked them out. They were probably hiding in it. It is also a bug factory.`

Dave B,

Have you recently fertilized or otherwise had a slug of nutrients added to your water...maybe a big runoff?

Don't expect an overnight miracle with the Tilapia. It took a while to grow all that algae and it will take the Tilapia a while to clean it up, but they will indeed clean it up over time.

They are more effective at getting the algae before it floats, not after. For the most part, I've seen them eat the algae on the bottom before it is released to the top, but this weekend I observed Tilapia feeding on the floating stuff also.

It seems to be a banner year for the filamentous algae in my area. Our new 3/4 acre pond is about 1/4 to 1/3 covered with it. However, I've noticed a couple of much larger local lakes that usually don't have it are having problems as well. Could be the cool late spring we had.

Coach B,

Good analysis. I've been wondering the same thing and hadn't made the association with the weather, but I'm thinking you are very right. We actually had a spring in East Texas this year for the first time I can ever remember...usually its just straight to summer temps.

Meadowlark,

I'm convinced certain species of filamentous algae perfer colder water. Or unseasonibly cold temps followed by a quick warm up with wind could bring up nutrients from the bottom quickly and fire it up.

My trout pond has filamentous algae even in winter, and it becomes quite prolific around the edges into late spring. Then once early summer comes around it vanishes and the trout pond is dominated by chara. I think chara apparently has a competitive advantage in the slightly warmer water.

Cecil,

I agree with you...also am amazed at the ability of some algae forms to completely disappear after a real good rain. It would be interesting to know more about these "plants"..and by so doing, maybe be better managers of what they do to us and our ponds.

p.s. what do you do to control chara? About all I do is employ Tilapia and grass carp.

I'm not an expert on algae and plants. In fact, I've always thought Cecil and Bill Cody knew more than me. So, take this with a grain of salt.

As I read this string, I thought of the natural progression that occurs in our waters from green algae to blue-green algae as water warms. Green algae "bloom" at cooler temps, and then are replaced later by the blue-green algae blooms as water warms.

The two most common filamentous algae mats around here are Cladophora and Spirogyra. Those are both genus names (I'm not even sure if they have common names). If you grab some of your filementous algae and rub it between your fingers, the Spirogyra will feel "greasy" while the Cladophora will feel rough.

Anyway, I do have a point. :-) Both Spirogyra and Cladophora are green algae. So, the temperature stuff as discussed above may just apply.

Dave B. I don't think the thick mats of filamentous algae will have a big impact on the success of bgill spawning in your lake. Keep in mind that the male fish builds, guards and keeps the bowl, shaped, nest area clean during the egg laying, incubation & hatching, and until young leave the nest. Once the young fish leave the nest, the occasional fish probably gets entangled in algae mats but I think the majority are able to avoid entanglement and a very low percentage of deaths occur.

One exception to this opinion - Hydrodictyon (High-drow-dick-ton). This is a green filamentous algae that is commonly called "fish net algae". It has the appearence and shape of a fish gill net. Small fish try to swim through it and get caught / entrapped in the openings by the gills and soon suffocate.

I have always thought that when the FA "disappears" after a good rain, it sinks due to the trapped oxygen bubbles which floated it up being knocked off by the raindrops. Anyone have a better/more correct explanation?

Here's a dumb question...are the different colors of algae indicative of an actual different type of algae? In our area, I've seen all different algae colors, including a yucky brown, that appears to be the same species or type.

I can't discern any different types by feel either. It all feels bad.

If rain water really drives out oxygen causing the algae to disappear (or whatever cause rain water exerts on the algae), then why wouldn't a water hose sprayed on an algae mat get rid of it? I don't know, maybe it would...someone should try that. That may be a simple solution to many folks problems. Anybody ever tried that?

Theo - The floating filamentous algae has broken lose from the pond bottom. This floating algae is in the last or final stages of life and is at the surface due to entraped "air" until either wave action or a heavy rain event beats it up and causes it to sink. You are probably correct, the agitation from a "beating" rain causes release of the entraped air which keeps the FA on the surface.

So, Bill, why not spray those mats with a water hose and get rid of them? Would that work?

I posted several days ago that my floating FA was about 60% gone after ten days of exposure to Tilapia nilotica stocked at 13 lb an acre (av. weight, 1 lb.) It continues to break into smaller floating pieces, now averaging about 18" in diameter, and only about 20% is left.

I also mentioned that I am not sure how much of this is due to Tilapia. We haven't had a rain in a while, but the FA continues to disappear. I have a good planktonic bloom, so I suppose there is little recruitment from new bottom growth. On the other hand, there is still plenty of the yucky black rough stuff on the bottom--enough to make jig fishing problematic.

I have checked on how well nilotica could be nourished by a heavy bloom of phytoplankton, and as best I can tell, they could live entirely off the stuff with no other food. I don't see any hitting the pellets when I hand-feed my bream.

BTW, my neighbor's grandson caught one of his Tilapia on a cricket being dragged through a BG bed. Talk about one excited young man! The fish sucked cricket and hook deeper than they could see, so they cut the line and hoped for the best.

The Tilapia breeders must be working 24/7 to supply everyone who wants them in our area. I must admit to being a true believer. I have parked my mower next to the pond and am hoping they will cut my grass next.
Lou 13.5

I'm convinced there is something chemical going on too. Rain typically has a PH lower than 7.0 while my water ranged from 7.5 to 8.5.

I have removed Chara in the past manually with a rake but don't want to remove too much as I prefer it over the FA. Additionally I'm convinced it acts as a nitrifying medium and helps me maintain my equiv. of 5000 lbs. per acre of trout in my little 1/10th acre pond.

I do have two grass carp in the pond but they don't seem to be moving a lot of vegatation probably due to the cool temps that never get above 65 F. They use grass carp in trout ponds in Manitoba and they say you jut have to plant more to make up for the lower temps.