Thursday, June 4, 2015

June 2, 2015: Erv's Field Notes #79

This cup plant was infested with red aphids and lady bug beetles were there to feed on them. 6/3/15 (Erv Klaas)

Sunday, May 31, 2015, 3 pm, Sunny, slight breeze, Temperature, 72 degrees F. A beautiful day.

The park was crowded today with walkers, bikers, skaters, and fishers. I took a walk along the north shore of the lake this afternoon. The cool spring has delayed the emergence of damselflies and dragonflies. I saw three Eastern Forktail damselflies; two adult males and one immature male. This little insect emerges early and can be seen all summer and into fall. In a couple of weeks I can expect to find as many as 15-20 species of odonates along this stretch of shoreline. Two mallard drakes were hanging out near the shore. I have seen these two guys here before. I wonder if there are hens nesting nearby or if these are bachelors who didn’t find a mate this year.

Many regular visitors to the park recently have noticed that water quality has not been good. On or about May 14, the lake looked very muddy, as if a huge rain event had brought in a load of silt. However, we have not had much rain and no evidence could be found of any severe erosion occurring in the watershed. Some of us think bottom sediment must have been disturbed to cause the muddy condition. Today, the water was still murky but it seems to be slowly clearing.

I contacted Friends member Jeff Kopaska, DNR fisheries biologist, for an explanation and he in turn contacted Michelle Balmer at the DNR, who studied under Dr. John Downing at ISU. Here is Michelle’s explanation:

“Yes, Ada Hayden is the worst I’ve ever seen it. I was there last Wednesday paddling with some friends. I took a water sample and looked at it under our scope here at the Wallace building. As far as I can tell, two things are happening right now in the lake. First, there was a benthic algae bloom earlier this season that is dying off. This would explain the floating brownish mats (brown sludge) that are coming up around parts of the lake. The second thing is most likely an intense diatom bloom. We’ve had reports of several other blooms of a similar nature from around the state and the lake smell is consistent with a bloom. Diatoms often bloom a brownish color because of the pigments they produce, so again, this seems to make sense. The water sample I looked at had a lot of small filaments of algae, although I couldn’t look at it with a very high resolution. This is consistent with several types of algae blooms (including some forms of diatoms). The sample did not look like sediment in the water, and while water clarity has been reduced, it still is better than if the lake were filled with sediment. My best guess (without any water quality samples) would be that the lake had high phosphorus inputs throughout the winter from construction projects and phosphorus from geese (a large population kept the South Basin open all winter) that fueled the bloom as water temperatures rose and the water clarity remained excellent.”

I was pleased to see a healthy population of swamp milkweeds growing in several places along the north and west shorelines of the lake. I also saw at least a dozen common milkweeds in this area. This is good news for the monarch butterfly because the national population has been in steep decline. Adult monarchs lay their eggs only on milkweeds because milkweeds are obligate food for the larvae to develop. Dr. Chip Taylor, Kansas University, has determined that the large majority of Monarchs that migrate to the highlands of western Mexico to spend the winter, originate in the Midwest. Common milkweeds were once a common weed in corn and soybean fields. Modern agriculture has effectively eliminated milkweeds from crop fields. Thus, reproduction of Monarchs has been greatly reduced. Efforts are now being made to expand milkweed habitat throughout the Midwest through the planting of “way stations” in parks, roadsides, and even urban backyards. We can be proud that Hayden Park has an abundance of milkweeds for Monarchs.

I am sorry for the infrequency of my field notes. I have developed neuropathy in my legs and feet and it is difficult for me to walk very far. So, I don’t get to the park as often as I would like.

Erv Klaas

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