Why was there so much Filamentous Algae
on the lake bottom?
by Bruce Gilbertson, Area Fisheries Supervisor, Minnesota Department of Natural Resources
Lakeshore property owners on several area lakes, including Diamond Lake, have wondered why there is so much filamentous algae growing on the lake bottom this year.
This was, by most accounts, an unusual spring. It was wet and colder than normal, and lasted for a long time. Lake residents typically see a plankton algae bloom about one week after a "first flush" of nutrients following a significant rain event, especially as the water warms. Plankton algae basically is the small green dots floating in the water. More severe blooms can look like green paint. The early season algae bloom usually lasts about one to two weeks. Rooted aquatic plants begin to take up available nutrient, then the water clears up for a time. Plankton algae can again become a nuisance later in the summer.
This year, we got the spring flush of nutrients to lakes. But, because it was so unseasonably cold, rooted plants and plankton algae were not able to use the nutrient entering area lakes. Growing conditions were wrong for them. The group of plants that could use the nutrient were filamentous algae. They flourished in the cool water and bath of available nutrients and created a greenish to green-black mat of algae "hair" on the lake bottom.
By the time you read this explanation, we should be returning to "normal" early summer lake conditions. Rooted aquatic plants should be actively growing and plankton algae will be more noticeable, depending on rain amounts and available sunlight.
Most lake residents now know that efforts by the Diamond Lake Association to identify nutrient sources and develop plans with cooperating government agencies to reduce those sources will in the long run provide the best long term relief from poor water quality.
for us. It will be available for other uses on other lakes, thereby getting more use than if only earmarked for Diamond Lake. We can consider ourselves benefactors of other lakes besides our own.
As for the new grant, we applied for a continuation and received a $25,000 matching grant to run 3 years to April 11, 2004. We are now in the process of drawing up plans for expending the funds. Do you have any good ideas?
Exotic Problems
The Minnesota DNR has embarked upon a program in our area to try to control the spread of Eurasian watermilfoil and zebra mussels. By means of the boat license surcharge they have acquired enough funding to hire 37 members of the Minnesota Conservation Corp., an offshoot of the Depression Era CCC (Civilian Conservation Corp.), to stage an "awareness event", an education effort to raise the awareness of boaters about the exotics and how to keep them off and out of their boats. The weekend of June 9 they sent 6 inspectors to the county to serve 4 hour shifts at various boat landings. They were reportedly at the Diamond Lake County Park boat access on Saturday and Sunday afternoon, June 9 & 10.
According to Tiffany Knapp, DNR coordinator of the program, the spread of the nuisance plants and animals is not inevitable. Through careful efforts, people can help by making sure they don't give any free rides on their boats, trailers or in their live wells to the pests. While it is possible for waterfowl to spread the milfoil, the seeds are not very viable and the fragments not likely to survive the flight.
For those unfamiliar with Eurasian watermilfoil, it can be a substantial nuisance by forming extensive mats over the water surface. It obviously represents another blow to water quality. Zebra mussels pose a threat against other mussels and fish in general. They are filter feeders that strain tiny food particles from the water, depriving other forms of life in the food chain of that nourishment. Their larvae are microscopic and thus easily transported in bait buckets for infestation in new waters.
The DNR recommends the following precautions: remove plants and animals from your boat, trailer and accessory equipment before leaving the water access area; drain your livewells, bilge water and transom wells before leaving the water access area; empty your bait bucket on land, never into the water; wash your boat, trailer with hot water when you get home; learn what these organisms look like; consult the DNR for recommendations and permits before you try to control or eradicate an exotic pest. Readers who would like to learn more may do so by contacting Ms. Knapp at 651-284-3546.
NOTE: I did catch up with one of the Corps inspectors, Dan Riebe, on Saturday, June 30th. Dan is a New London resident and Luther College student whose love of the outdoors led him to apply for the position over the Internet. His job is to inform boaters of plants and animal pests, inspect their boats and (especially) trailers, and advise them on precautionary measures. Fines for violators can be stiff, and while Dan does not have any enforcement powers himself, he can call for assistance. That has not been necessary so far. Boaters are cooperative and happy to comply. Dan is convinced that the problems are controllable and the exotics can be kept out of the lakes with proper care.
Is it safe to eat a carp?
by the Corpulent Carp Connowever (condensed from the Weston West Virginia Carp Fishing Festival Website)
Who would ever want to eat such a dirty fish? Well, lots of people, and not just rednecks. In many European countries the carp is considered a delicacy. In Austria, for example, carp are raised in small "clean" water ponds and served as the main course at holiday feasts.
The key phrase here is "small clean water ponds". If the water is clean the Carp tastes much like any other freshwater fish. As the carp is constantly filtering the water in which it swims, it will take on the character of that water, just like the other fish in the neighborhood.
All fish are considered as healthy food sources and, when properly prepared, provide a diet high in protein and low in saturated fats. However, there are some risks, especially with those fish found in contaminated waters. Some contaminants can cause cancer. Some waters contain mercury, which inheres in fish tissue. PCBs on the other hand concentrate in the fat of fish and can be more easily removed. Larger, older fish which eat other fish accumulate more contaminants than smaller, younger fish.
Like the catfish and sucker, the carp is primarily a "bottom feeder", meaning it scours the bottom of the lake looking for prey that crawls or tries to hide in the weeds. This makes them more vulnerable to ingesting pollutants which sink to the bottom. Also carp have few natural enemies and tend to live longer and larger than other common species. But there are methods of reducing the risk, and this applies to ALL fish:
* Space out fish meals over several weeks or months
* Carefully follow fish advisories, such as those published by the DNR
* Limit the size and number of fish you eat
* Women of childbearing age and children should be especially careful.
If you're still interested, look for more information in future issues of the "News". We will discuss basic methods of cleaning and cooking fish. We are especially interested in carp stories, or any comment on this article. Or any other article!
